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Sample records for multislice helical computed

  1. Diagnosis of the nutcracker phenomenon by multislice helical computed tomography angiography

    Institute of Scientific and Technical Information of China (English)

    符伟军; 洪宝发; 肖越勇; 杨勇; 蔡伟; 高江平; 郭刚; 王晓雄

    2004-01-01

    @@ The nutcracker phenomenon refers to compression of the left renal vein between the aorta and the superior mesenteric artery, which results in renal venous hypertension and its clinical symptoms.1 This phenomenon is an unusual, but well-accepted cause of hematuria. As of now, it appears the nutcracker phenomenon is probably more common than previously suspected.2 To the best of our knowledge, however, there have been few trials investigating the use of multislice helical computed tomography angiography (CTA) of the renal vein along with measurements of the angles and distances between the aorta and the SMA in the diagnosis of the nutcracker phenomenon. The purpose of This work was to study the anatomic changes involved in the nutcracker phenomenon by comparing the vascular anatomy in patients with this phenomenon to that in healthy control subjects, and to assess the value of CTA in the diagnosis of this condition.

  2. Organ and effective doses in newborn patients during helical multislice computed tomography examination

    Science.gov (United States)

    Staton, Robert J.; Lee, Choonik; Lee, Choonsik; Williams, Matt D.; Hintenlang, David E.; Arreola, Manuel M.; Williams, Jonathon L.; Bolch, Wesley E.

    2006-10-01

    In this study, two computational phantoms of the newborn patient were used to assess individual organ doses and effective doses delivered during head, chest, abdomen, pelvis, and torso examinations using the Siemens SOMATOM Sensation 16 helical multi-slice computed tomography (MSCT) scanner. The stylized phantom used to model the patient anatomy was the revised ORNL newborn phantom by Han et al (2006 Health Phys.90 337). The tomographic phantom used in the study was that developed by Nipper et al (2002 Phys. Med. Biol. 47 3143) as recently revised by Staton et al (2006 Med. Phys. 33 3283). The stylized model was implemented within the MCNP5 radiation transport code, while the tomographic phantom was incorporated within the EGSnrc code. In both codes, the x-ray source was modelled as a fan beam originating from the focal spot at a fan angle of 52° and a focal-spot-to-axis distance of 57 cm. The helical path of the source was explicitly modelled based on variations in collimator setting (12 mm or 24 mm), detector pitch and scan length. Tube potentials of 80, 100 and 120 kVp were considered in this study. Beam profile data were acquired using radiological film measurements on a 16 cm PMMA phantom, which yielded effective beam widths of 14.7 mm and 26.8 mm for collimator settings of 12 mm and 24 mm, respectively. Values of absolute organ absorbed dose were determined via the use of normalization factors defined as the ratio of the CTDI100 measured in-phantom and that determined by Monte Carlo simulation of the PMMA phantom and ion chamber. Across various technique factors, effective dose differences between the stylized and tomographic phantoms ranged from +2% to +9% for head exams, -4% to -2% for chest exams, +8% to +24% for abdominal exams, -16% to -12% for pelvic exams and -7% to 0% for chest-abdomen-pelvis (CAP) exams. In many cases, however, relatively close agreement in effective dose was accomplished at the expense of compensating errors in individual organ

  3. Multislice helical computed tomography in the evaluation of lumbar spine diseases; Tomografia computadorizada 'multislice' no diagnostico das afeccoes da coluna lombar

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    Rosemberg, Laercio Alberto; Rios, Adriana Martins; Almeida, Milena Oliveira [Hospital Israelita Albert Einstein, Sao Paulo, SP (Brazil)]. E-mail: laercio@einstein.br; Garbaccio, Viviane Ladeira; Kim, Nelson Ji Tae; Daniel, Mauro Miguel; Funari, Marcelo Buarque de Gusmao [Hospital Israelita Albert Einstein, Sao Paulo, SP (Brazil). Dept. de Imagem

    2003-06-01

    Multislice computed tomography has advantages in comparison to conventional computer tomography such as reduction in study time, lower radiation dose, fewer metal artifacts and high quality multiplanar reformatting and three-dimensional reconstructions. We reviewed approximately 300 lumbar spine examinations and selected the most illustrative cases including congenital anomalies, degenerative lesions, spinal infections, neoplasms traumatic injuries, spondylolysis and postoperative changes. In the majority of the cases the high quality multiplanar reformatted and volume reconstructions of multislice computed tomography allowed better evaluation of the lesions, particularly in the cases of complex anatomy (author)

  4. The accuracy and optimal slice thickness of multislice helical computed tomography for right and left ventricular volume measurement

    Institute of Scientific and Technical Information of China (English)

    崔炜; 近藤武; 安野泰史; 郭玉印; 佐藤贵久; 皿井正義; 篠崎仁史; 柿澤聡士; 杉浦厚司; 大岛慶太; 片田和廣; 菱田仁

    2004-01-01

    Background Multislice helical computed tomography (MSCT) has been used to depict coronary anatomy noninvasively, and proved useful for evaluating ventricular function. The aim of our study was to assess the accuracy of ventricular volume as measured by MSCT. Methods Fourteen human left ventricular (LV) and 15 right ventricular (RV) casts were scanned by MSCT. A series of LV and RV short-axis images were reconstructed later with slice thickness of 2.0 mm, 3.5 mm, 5.0 mm, 7.0 mm, and 10.0 mm. Ventricular volume was calculated by the multislice tomographic Simpson's method. True LV and RV cast volumes were determined by water displacement. Results Both calculated LV and RV volumes correlated highly with the corresponding true volumes (all r>0.95, P<0.01). But with slice thickness from 2.0 mm to 10.0 mm, MSCT scanning overestimated the corresponding true volume by (3.21±5.95) ml to (12.58±8.56) ml for LV and (10.22±8.45) ml to (23.91±12.24) ml for RV (all P<0.01). There was a very high correlation between the overestimation and the selected slice thickness for both LV and RV volume measurements (r=0.998 and 0.996, P<0.01, respectively). However, when slice thickness was reduced to 5.0 mm, the overestimation for both LV and RV volume measurements became nonsignificant for slice thickness from 2.0 mm to 5.0 mm. Conclusions Both LV and RV volumes can be accurately estimated by MSCT. Thinner slice has more accurate calculated volume. However, 5.0 mm slice thickness is thin enough for an accurate measurement of LV or RV volume.

  5. Anti-aliasing weighting functions for multislice helical CT

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    La Riviere, Patrick J.; Pan, Xiaochuan

    2002-05-01

    We develop a new projection weighting function for interpolation and reconstruction of multi-slice helical computed tomography data with the hope of reducing longitudinal aliasing in reconstructed volumes. The weighting function is based on the application of the Papoulis generalized sampling theorem to the interlaced longitudinal samples acquired by the multi-slice scanner. We call the approach 180MAA, for multi-slice anti-aliasing. For pitch 3, the 180MAA approach yields high-quality images of the 3D Shepp-Logan phantom as well as a longitudinal MTF superior to that of the 180MLI approach, which is based on the use of linear interpolation. However, it is not as successful at mitigating aliasing as had been doped due to the presence of a significant and unexpected aliasing component that can be attributed to the small cone angle in multi-slice helical CT. The presence of this effect is interesting and significant in its own right, however.

  6. Detection of unruptured cerebral artery aneurysms by MRA at 3.0 tesla: comparison with multislice helical computed tomographic angiography

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    Numminen, Jussi; Porras, Matti; Kangasniemi, Marko (Dept. of Radiology, Helsinki Medical Imaging Center, Helsinki Univ. Central Hospital, Helsinki (Finland)), email: jussi.numminen@hus.fi; Tarkiainen, Antti (Advanced Magnetic Imaging Center, Helsinki Univ. of Technology, Espoo (Finland)); Niemelae, Mika; Hernesniemi, Juha (Dept. of Neurosurgery, Helsinki Univ. Central Hospital, Helsinki (Finland))

    2011-07-15

    Background: Computed tomographic angiography (CTA) has become the primary non-invasive method for detection of cerebral artery aneurysms in many neurovascular centers. Purpose: To compare MR-angiography at a 3.0 tesla (3T) scanner to CTA in the detection of unruptured intracranial aneurysms. Material and Methods: CTA and 3T MRA data from 60 patients were evaluated. CTA was obtained with a 4-16-row helical CT-scanner after administration of 120 cc intravenous contrast agent, MRA was performed by a 3T MR-scanner using time-of-flight pulse sequence. Results: Fifty-five cerebral artery aneurysms were detected by MRA and 47 aneurysms by CTA. Most of the aneurysms detected by MRA but not by CTA were small internal carotid artery (ICA) aneurysms. Bone structures and venous enhancement deteriorated CTA accuracy, especially in skull base. In one patient a fairly large anterior communicating artery aneurysm was not visible in MRA due to spin saturation, although it was clearly visualized in CTA. After contrast injection the aneurysm was also seen in MRA. Although the overall image quality of MRA and CTA were comparable, MRA was more susceptible to artifacts and thus re-formatted surface-shaded volume rendered 3-dimensional images of aneurysms from MRA were inferior compared to those from CTA. Conclusion: MRA at 3T appears to be at least as sensitive as CTA in the detection of unruptured cerebral artery aneurysms, however image quality control is crucial and contrast agent enhances visualization of complex and large aneurysms

  7. USING OF MULTISLICE HELICAL CT COLONOGRAPHY IN PATIENTS WITH MALIGNANT LESIONS OF COLON

    Institute of Scientific and Technical Information of China (English)

    Ming-wei Qin; Wei-dong Pan; Guan-ning Cong; Yun Wang; Yun-qing Zhang; Wen-bin Mou; Zheng-yu Jin

    2005-01-01

    Objective To investigate the techniques and clinical applications of multislice helical computed tomography (CT) colono graphy in colonic lesions. Methods Fifty-nine patients with malignant lesions of colon underwent volume scanning using multislice helical CT. Four types of reconstruction including CT virtual colonoscopy (CTVC), shaded surface display (SSD), Raysum, and mu ltiple planar reconstruction (MPR) were used for image post-processing. The results were compared with those of colonos copy and pathology. Results Multislice helical CT colonography detected 54 colorectal carcinomas, 4 adenomas with focal carcinoma, 1 non-Hodgkin's lymphoma (NHL). The lesions' number, size, location, morphology, stricture of intestinal cavity, infiltration, and metastasis were shown satisfactorily by multislice helical CT colonography. Whole colon could be shown in all patients. CT colonography displayed 4 synchronous colonic tumors, 1 ascending colon carcinoma combined with left renal carcinoma among 54 patients with colonic carcinomas. The accuracy of location of CT colonography was 100%. There were 9 cases that CT showed the tumor location was different from the finding of conventional colonoscopy, while all of the CT location were proven exact by operation. CT colonography also displayed the infiltration of serous layer and fatty tissue in 45 cases; 21 cases matched the pathological results in all the 24 cases of suspicious lymph node metastasis, the sensitivity was 87.5%, the specificity was 90.6%; 9 cases hepatic metastasis, 2 ovarian metastasis, and 1 double adrenal gland metastasis.Conclusions Multislice helical CT colonography is effective in preoperative diagnosis, location, stage, and making treatment plan of colorectal carcinoma. It can display the portion not seen during colonoscopy and may have an adjunctive role.

  8. Multidetector-row helical computed tomography in the evaluation of cervical spine disorders; Tomografia computadorizada multislice no diagnostico das afeccoes da coluna cervical

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    Rosemberg, Laercio Alberto; Almeida, Milena Oliveira; Rios, Adriana Martins; Garbaccio, Viviane Ladeira; Kim, Nelson Ji Tae; Daniel, Mauro Miguel; Funari, Marcelo Buarque de Gusmao [Hospital Israelita Albert Einstein, Sao Paulo, SP (Brazil). Dept. de Imagem]. E-mail: laercio@einstein.br

    2003-07-01

    Multidetector-row computed tomography (MRCT) has advantages in comparison to conventional helical computed tomography, such as reduction of study time, lower radiation doses, fewer metallic artifacts and high quality multiplanar reformatting and three dimensional reconstructions. We reviewed 150 cervical spine examinations and selected the most illustrative cases including congenital anomalies, degenerative lesions, spinal infections, neoplasms, traumatic injuries and postoperative abnormalities. The quality of multiplanar reformatting and volume reconstructions of the MRCT made the detection and evaluation of most of cases with complex anatomy easier and more precise. (author)

  9. Efficacy of multislice computed tomography for gastroenteric and hepatic surgeries

    Institute of Scientific and Technical Information of China (English)

    Hiroshi Ohtani; Mitsuo Tsubakimoto; Hidemi Kawajiri; Yuichi Arimoto; Koichi Ohno; Yasuhisa Fujimoto; Hiroko Oba; Kenji Adachi; Masaya Hirano; Shoichi Terakawa

    2005-01-01

    AIM: To determine the efficacy of multislice CT for gastroenteric and hepatic surgery.METHODS: Dual-phase helical computed tomography was performed in 50 of 51 patients who underwent gastroenteric and hepatic surgeries. Twenty-eight, eighteen and four patients suffering from colorectal cancer, gastric cancer,and liver cancer respectively underwent colorectal surgery (laparoscopic surgery: 6 cases), gastrectomy, and hepatectomy. Three-dimensional computed tomography imaging of the inferior mesenteric artery, celiac artery and hepatic artery was performed. And in the follow-up examination of postoperative patients, multiplanar reconstruction image was made in case of need.RESULTS: Scans in 50 patients were technically satisfactory and included in the analysis. Depiction of major visceral arteries, which were important for surgery and other treatments, could be done in all patients.Preoperative visualization of the left colic artery and sigmoidal arteries, the celiac artery and its branches, and hepatic artery was very useful to lymph node dissection,the planning of a reservoir and hepatectomy. And multiplanar reconstruction image was helpful to diagnosis for the postoperative follow-up of patients.CONCLUSION: Three-dimensional volume rendering or multiplanar reconstruction imaging performed by multislice computed tomography was very useful for gastroenteric and hepatic surgeries.

  10. The effect of pitch in multislice spiral/helical CT; L'effet du pas dans la tomodensitometrie spiralee/helicoidale multidetecteurs

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    Wang, G.; Vannier, M.W. [Iowa Univ., Dept. of Radiology, Iowa City, IA (United States)

    2000-07-01

    The purpose of this study is to understand the effect of pitch on raw data interpolation in multislice spiral/helical computed tomography (CT) and provide guidelines for scanner design and protocol optimization. Multislice spiral CT is mainly characterized by the three parameters: the number of detector arrays, the detector collimation, and the table increment per x-ray source rotation. The pitch in multislice spiral CT is defined as the ratio of the table increment over the detector collimation in this study. In parallel to the current framework for studying longitudinal image resolution, the central fan-beam rays of direct and opposite directions are considered, assuming a narrow cone-beam angle. Generally speaking, sampling in the Radon domain by the direct and opposite central rays is nonuniform along the longitudinal axis. Using a recently developed methodology for quantifying the sensibility of signal reconstruction from non-uniformly sampled finite points, the effect of pitch on raw data interpolation is analyzed in multislice spiral CT. Unlike single-slice spiral CT, in which image quality decreases monotonically as the pitch increases, the sensibility of raw data interpolation in multislice spiral CT increases, suggesting that image quality does not decrease monotonically in this case. The most favorable pitch can be found from the sensitivity-slice spiral CT is provided. The study on the effect of pitch using the sensitivity analysis approach reveals the fundamental characteristics of raw data interpolation in multislice spiral CT, and gives insights into interaction between pitch and image quality. These results may be valuable for design of multislice spiral CT scanners and imaging protocol optimization in clinical applications. (authors)

  11. Dynamic multislice helical CT of maxillomandibular lesions. Distinction of ameloblastomas from other cystic lesions

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    Tozaki, Mitsuhiro; Hayashi, Katsuhiko; Fukuda, Kunihiko [Jikei Univ., Tokyo (Japan). School of Medicine

    2001-10-01

    The purpose of this study was to evaluate the clinical usefulness of dynamic multislice helical CT in differentiating ameloblastoma from other cystic lesions in cases of maxillomandibular cystic lesions. The study included 32 patients with maxillomandibular cystic lesions (ameloblastoma [n=6], myxofibroma [n=1], odontogenic keratocyst [n=3], dentigerous cyst [n=11], radicular cyst [n=11], and paradental cyst [n=2]). Dynamic study was performed before and 30 sec, and 90 sec after intravenous contrast medium administration. CT density values and percentage of density increase were calculated at 30 and 90 sec. In five cases of ameloblastoma, a rapidly enhancing area was detected within the cystic lesions at 30 sec, while no apparent rapid enhancement was seen in the other cystic lesions. Three cysts showed gradual enhancement in the marginal area at 90 sec. Comparing ameloblastoma and other kinds of cysts, we found significant differences in the percentage of density increase at 30 sec (p<0.01) and 90 sec (p<0.05). Dynamic multislice helical CT is useful in the diagnosis of cystic lesions of the maxillomandibular region, especially in the detection of neovascularities in ameloblastoma. (author)

  12. Role of Early Arterial Phase Multislice Helical CT Angiography in Evaluation of Hepatocellular Carcinoma

    Institute of Scientific and Technical Information of China (English)

    TANGBinghang; HEYaqi; LILiangcai; HUANGDecheng; WURenguo; YUYuanlong

    2005-01-01

    Objective: To investigate the clinical application of early arterial phase multislice CT angiography (MSCTA) of hepatic vessels in evaluation of middle or advanced stage hepatocellular carcinoma.Methods: Trigger Bolus program was used to carry out MSCTA in early and late arterial phases and portal vein phase with single breath holding. Hepatic vessels were reconstructed from the original images of early arterial phase by post processing. The blood supply of tumor and normal liver tissue and the appearances of venous thrombosis and arteriovenous shunts were analyzed. Results: The MSCTA with early arterial phase could perfectly display the origin, shape and amount of feeding vessels to normal liver tissue and tumor in middle or advanced stage hepatocellular carcinoma. It had the ability of displaying the arteriovenous shunts better than that in conventional dual phased liver scanning. Conclusion: MSCTA of hepatic vessels with early arterial phase acquisition using multislice helical CT in middle or advance stage hepatocellular carcinoma has favorable and promising application. It can be used as an imaging method for comprehensive assessment of the hepatocellular carcinoma before treatment.

  13. Approximations of noise covariance in multi-slice helical CT scans: impact on lung nodule size estimation.

    Science.gov (United States)

    Zeng, Rongping; Petrick, Nicholas; Gavrielides, Marios A; Myers, Kyle J

    2011-10-07

    Multi-slice computed tomography (MSCT) scanners have become popular volumetric imaging tools. Deterministic and random properties of the resulting CT scans have been studied in the literature. Due to the large number of voxels in the three-dimensional (3D) volumetric dataset, full characterization of the noise covariance in MSCT scans is difficult to tackle. However, as usage of such datasets for quantitative disease diagnosis grows, so does the importance of understanding the noise properties because of their effect on the accuracy of the clinical outcome. The goal of this work is to study noise covariance in the helical MSCT volumetric dataset. We explore possible approximations to the noise covariance matrix with reduced degrees of freedom, including voxel-based variance, one-dimensional (1D) correlation, two-dimensional (2D) in-plane correlation and the noise power spectrum (NPS). We further examine the effect of various noise covariance models on the accuracy of a prewhitening matched filter nodule size estimation strategy. Our simulation results suggest that the 1D longitudinal, 2D in-plane and NPS prewhitening approaches can improve the performance of nodule size estimation algorithms. When taking into account computational costs in determining noise characterizations, the NPS model may be the most efficient approximation to the MSCT noise covariance matrix.

  14. Non-invasive coronary angiography with multislice spiral computed tomography: impact of heart rate

    NARCIS (Netherlands)

    B.J.W.M. Rensing (Benno); R.J.M. van Geuns (Robert Jan); J. Vos (Jeroen); P.M.T. Pattynama (Peter); G.P. Krestin (Gabriel); P.J. de Feyter (Pim); P.W.J.C. Serruys (Patrick); K. Nieman (Koen)

    2002-01-01

    textabstractOBJECTIVE: To evaluate the impact of heart rate on the diagnostic accuracy of coronary angiography by multislice spiral computed tomography (MSCT). DESIGN: Prospective observational study. PATIENTS: 78 patients who underwent both conventional and MSCT coronary angiograp

  15. Multislice Computed Tomography Accurately Detects Stenosis in Coronary Artery Bypass Conduits

    Science.gov (United States)

    Duran, Cihan; Sagbas, Ertan; Caynak, Baris; Sanisoglu, Ilhan; Akpinar, Belhhan; Gulbaran, Murat

    2007-01-01

    The aim of this study was to evaluate the accuracy of multislice computed tomography in detecting graft stenosis or occlusion after coronary artery bypass grafting, using coronary angiography as the standard. From January 2005 through May 2006, 25 patients (19 men and 6 women; mean age, 54 ± 11.3 years) underwent diagnostic investigation of their bypass grafts by multislice computed tomography within 1 month of coronary angiography. The mean time elapsed after coronary artery bypass grafting was 6.2 years. In these 25 patients, we examined 65 bypass conduits (24 arterial and 41 venous) and 171 graft segments (the shaft, proximal anastomosis, and distal anastomosis). Compared with coronary angiography, the segment-based sensitivity, specificity, and positive and negative predictive values of multislice computed tomography in the evaluation of stenosis were 89%, 100%, 100%, and 99%, respectively. The patency rate for multislice compu-ted tomography was 85% (55/65: 3 arterial and 7 venous grafts were occluded), with 100% sensitivity and specificity. From these data, we conclude that multislice computed tomography can accurately evaluate the patency and stenosis of bypass grafts during outpatient follow-up. PMID:17948078

  16. Myocardial bridging: evaluation with multislice computed tomography coronary angiography

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    Barros, M.V.L. de; Rabelo, D.R.; Nunes, M.C.P.; Siqueira, M.H.A. [Mater Dei Hospital, Belo Horizonte, MG (Brazil)

    2012-04-15

    Myocardial bridging (MB) is defined as a segment of a major epicardial coronary artery that proceeds intramurally through the myocardium beneath the muscle bridge. Although MB is clinically silent in most cases, it has been associated with myocardial ischemia, myocardial infarction, arrhythmia, and sudden death. Conventional coronary angiography (CCA) is the gold standard for detection, but it is invasive and may not be sensitive enough to detect a thin bridge. Recently, multislice computed tomography coronary angiography (MCTCA) have made possible the clear detection of the entire running courses of coronary arteries and the MB itself. Objective: To evaluate the prevalence MB in patients suspect to coronary artery disease submitted to MCTCA and assessing the predictive value of this method in the midterm. Methods: 498 consecutive patients were examined by MCTCA for the diagnosis of coronary artery disease and followed for a mean follow-up of 17 months for the occurrence of cardiovascular events (death, hospitalization and / or revascularization myocardial). Results: The mean age of patients was 58.4 ± 12.5 years old, 74.3% male. Among the patients, 6,02% (30 patients) showed MB. The major indications were angina pectoris in 45,8% and positive stress testing in 33,3%. 62,5% showed absent atherosclerotic disease and only 1 patient showed moderade descending anterior stenosis. During the follow-up none patient showed hard events. Conclusion: Patients with MB could present with angina pectoris and positive stress testing and showed midterm excellent prognosis. MCTCA is an alternative noninvasive imaging tool that allows for easy and accurate evaluation of MB.

  17. Multislice computed tomography angiography findings of chronic small bowel volvulus with jejunal diverticulosis.

    Science.gov (United States)

    Li, Xiao-Bing; Guan, Wen-Xian; Gao, Yuan

    2010-07-01

    A volvulus, which is torsion of the bowel and its mesentery, is a medical emergency. Small bowel volvulus rarely occurs in adults, although it has been reported in the presence of small bowel diverticulum. Multislice computed tomography (CT) angiography, by demonstrating the mesenteric vessels, can be of help in the diagnosis of small bowel volvulus, especially when CT or gastrointestinal studies fail to show the diverticulum. We present the multislice CT angiography findings of a 64-year-old woman with chronic intermittent volvulus resulting from jejunal diverticulosis, surgically confirmed. To our knowledge, no similar case has been reported previously in the literature.

  18. [The effect of the severity of congenital pectus excavatum on the cardiac morphology in children: evaluation with multislice helical CT].

    Science.gov (United States)

    Lu, Tao; Deng, Kaihong

    2013-12-01

    This paper is aimed to evaluate the CT manifestation of congenital pectus excavatum and its effect on the cardiac morphology. CT features of 34 children with pectus excavatum were retrospectively reviewed. The Haller index (HI), CT depression index (CTDI), cardiac rotation angle (CRA), pulmonary vein angle (PVA), cardiac compression index (CCI) and cardiac asymmetry index (CAI) were measured from the images on the PACS system. The relationships among these indexes were evaluated. The HI was 4.12 +/- 1.48, the CTDI was 2.39+/- 0.70, CRA was (53.52 +/- 7.68) degrees, PVA was (66.51 +/- 11.02) degrees, CCI was 2.43 +/- 0.95, and CAI was 1.55 +/- 0.56. There was statistical significance of CCI and CAI between children with severe or slight pectus excavatum. The HI and CTDI were positively related with CCI and CAI respectively, whereas there was no statistical significance of CRA and PVA between children with severe or slight pectus excavatum. There was no statistical significance of HI, CTDI, CRA, PVA, CCI and CAI among different age groups. The morphological change of the heart compressed in children with pectus excavatum can be accurately evaluated by multislice helical CT.

  19. Evaluation of multislice computed tomographic perfusion imaging and computed tomographic angiography on traumatic cerebral infarction

    Institute of Scientific and Technical Information of China (English)

    XU Fang-hong; CHEN Wei-jian; YANG Yun-jun; DUAN Yu-xia; FU Feng-li

    2008-01-01

    Objective: To evaluate the application value of multislice computed tomographic perfusion imaging (MSCTPI) and multislice computed tomographic angiography (MSCTA) on traumatic cerebral infarction. Methods: MSCTA was performed on 10 patients who were initiailly diagnosed as traumatic cerebral infarction by normal conventional computed tomography (NCCT), among whom, 3 patients were examined by MSCTPI simultaneously. Reconstructed images of the intracranial artery were made with techniques of maximum intensity projection (MIP) and volume rendering (VR) from MSCTA scanning data. Then the graph of function of four parameters, regional cerebral blood flow (Rcbf), regional cerebral blood volume (Rcbv), mean transit time (MTT), and time to peak (TTP), acquired by the perfusing analysis software was obtained. Results: Among the 10 patients with traumatic cerebral infarction, 6 showed complex type on NCCT, which depicted abnormality on MSCTA, and 4 showed simple type on NCCT, which had negative results on MSCTA. Among the 4 patients with abnormal great vessels, 2 suffered from steno sis or occlusion of the middle cerebral artery, 1 from spasm of the anterior cerebral artery, and 1 from spasm of the vertebral-basal artery. The image of MSCTPI of 1 patient with massive cerebral infarction on the right cerebral hemisphere confirmed by CT was smaller than those of the other patients, which showed occlusion of the ipsilateral middle cerebral artery on MSCTA. Among the 6 patients whose MSCTA showed no abnormality, 4 showed simple infarction and 2 showed complex infarction. The infarction focus of 5 patients occurred in the basal ganglia and 1 in the splenium of corpus callosum. Among the 2 cases of small cerebral infarction volume on NCCT, one was normal, the other showed hypoperfusion on MSCTPI and was normal on MSCTA. Conclusion: The combination of MSCTPI and MSCTA is very useful for evaluating the change of intracranial artery in ischemic regions and assessing the cerebral

  20. Imaging skeletal anatomy of injured cervical spine specimens: comparison of single-slice vs multi-slice helical CT

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    Obenauer, S.; Alamo, L.; Herold, T.; Funke, M.; Kopka, L.; Grabbe, E. [Department of Radiology, Georg August-University Goettingen, Robert-Koch-Strasse 40, 37075 Goettingen (Germany)

    2002-08-01

    Our objective was to compare a single-slice CT (SS-CT) scanner with a multi-slice CT (MS-CT) scanner in the depiction of osseous anatomic structures and fractures of the upper cervical spine. Two cervical spine specimens with artificial trauma were scanned with a SS-CT scanner (HighSpeed, CT/i, GE, Milwaukee, Wis.) by using various collimations (1, 3, 5 mm) and pitch factors (1, 1.5, 2, 3) and a four-slice helical CT scanner (LightSpeed, QX/i, GE, Milwaukee, Wis.) by using various table speeds ranging from 3.75 to 15 mm/rotation for a pitch of 0.75 and from 7.5 to 30 mm/rotation for a pitch of 1.5. Images were reconstructed with an interval of 1 mm. Sagittal and coronal multiplanar reconstructions of the primary and reconstructed data set were performed. For MS-CT a tube current resulting in equivalent image noise as with SS-CT was used. All images were judged by two observers using a 4-point scale. The best image quality for SS-CT was achieved with the smallest slice thickness (1 mm) and a pitch smaller than 2 resulting in a table speed of up to 2 mm per gantry rotation (4 points). A reduction of the slice thickness rather than of the table speed proved to be beneficial at MS-CT. Therefore, the optimal scan protocol in MS-CT included a slice thickness of 1.25 mm with a table speed of 7.5 mm/360 using a pitch of 1.5 (4 points), resulting in a faster scan time than when a pitch of 0.75 (4 points) was used. This study indicates that MS-CT could provide equivalent image quality at approximately four times the volume coverage speed of SS-CT. (orig.)

  1. Computer aided diagnosis of osteoporosis using multi-slice CT images

    Science.gov (United States)

    Takahashi, Eiji; Saita, Shinsuke; Kawata, Yoshiki; Niki, Noboru; Ito, Masako; Nishitani, Hiromu; Moriyama, Noriyuki

    2010-03-01

    The patients of osteoporosis comprised about 11 million people in Japan and it is one of the problems the aging society has. In order to prevent the osteoporosis, it is necessary to do early detection and treatment. The development of Multislice CT technology made it possible to perform the three dimensional (3-D) image analysis with higher body axis resolution and shorter scan time. The 3-D image analysis using multi-slice CT images of thoracic vertebra can be used as a support to diagnose osteoporosis and at the same time can be used for lung cancer screening which may lead to its early detection. We develop an automatic extraction algorithm of vertebra, and the analysis algorithm of the vertebral body using shape analysis and a bone density measurement for the computer aided diagnosis of osteoporosis.

  2. Value of multislice computed tomography in the diagnosis of acute mesenteric ischemia

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    Yikilmaz, Ali, E-mail: dryikilmaz@yahoo.com [Erciyes University, School of Medicine, Gevher Nesibe Hospital, Department of Radiology, Talas Yolu, 38038 Melikgazi, Kayseri (Turkey); Karahan, Okkes Ibrahim; Senol, Serkan; Tuna, Ibrahim Sacit [Erciyes University, School of Medicine, Gevher Nesibe Hospital, Department of Radiology, Talas Yolu, 38038 Melikgazi, Kayseri (Turkey); Akyildiz, Hizir Yakup [Erciyes University, School of Medicine, Gevher Nesibe Hospital, Department of General Surgery, Talas Yolu, 38038 Melikgazi, Kayseri (Turkey)

    2011-11-15

    Objective: To define the value of multislice computed tomography (CT) in the diagnosis of acute mesenteric ischemia (AMI). Materials and methods: Two hundred patients (age range: 20-92 years) who were referred to the emergency CT department with a clinical suspicion of AMI were prospectively included in the study. CT examinations were performed with a multislice (16) CT scanner and the protocol included pre-contrast, arterial and venous phase acquisitions. Images were evaluated by using multiplanar reconstruction, maximum intensity projection and volume-rendering techniques at the CT workstation. Results: Ninety-four patients (47%) underwent surgery for AMI or for other causes of acute abdominal pain. One hundred-six patients (53%) were followed conservatively according to clinical, radiologic and laboratory findings. Of the 94 patients who underwent surgery, 49 (25%) were found to have AMI. All of these 49 patients with a proven AMI diagnosis were diagnosed with CT. In the other 45 patients who underwent surgery, CT findings were negative for AMI. None of the patients, who were followed conservatively, were eventually diagnosed as having AMI except 1 patient. This patient was unfit for surgery although his clinical and radiologic findings were consistent with AMI and died in 3 days. The sensitivity and specificity values of CT for the detection of AMI were calculated to be 100% for each. Conclusions: Multislice CT is an effective imaging technique for the diagnosis of AMI with excellent sensitivity and specificity values.

  3. Diagnosis of lung embolism by V / Q scintigraphy. Pt. 3. Comparison with multislice-helical CT; V / Q-Szintigrafie zur Diagnostik der Lungenembolie. T. 3. Vergleich mit der Mehrzeilen-Spiral-CT

    Energy Technology Data Exchange (ETDEWEB)

    Schuemichen, C. [Rostock Univ. (Germany). Klinik und Poliklinik fuer Nuklearmedizin

    2008-12-15

    V / Q scintigraphy can be seen to be equal in many areas to the more modern multislice-helical CT in detecting acute pulmonary embolism and even to be superior with respect to sensitivity. Multislice-helical CT recognizes central emboli with high sensitivity and specificity, but deficits still remain in detecting peripheral embolisms, despite methodical improvements (increase up to 64 slices). Especially measured on the outcome, the overall sensitivity is still too low (ca. 75 %), the reason for this lies less in the image quality than in the evaluation. V / Q scintigraphy has deficits in detecting central emboli which either have no hemodynamic effects or are only partially occluding. Measured on the outsome, the overall sensitivity is still excellent, the number of symptomatic and fatal late embolisms in scintigraphically normal, untreated patients tends toward zero. Decisive for the prognosis are thus embolisms with hemodynamic effects in primary diagnostics. Unlike V / Q scintigraphy, multislice-helical CT also recognizes extrapulmonary diseases as alternative diagnoses, among these aortic dissection. The risk of tumor induction following radiation exposure is higher with multislice-helical CT than with V / Q scintigraphy by more than one order of magnitude. (orig.)

  4. Three dimensional evaluation of the aortic annulus using multislice computer tomography: Are manufacturer's guidelines for sizing for percutaneous aortic valve replacement helpful?

    NARCIS (Netherlands)

    C.J. Schultz (Carl); A. Moelker (Adriaan); N. Piazza (Nicolo); A. Tzikas (Apostolos); A. Otten (Amber); R-J.M. Nuis (Rutger-Jan); L.A.E. Neefjes (Lisan); R.J.M. van Geuns (Robert Jan); P.J. de Feyter (Pim); G.P. Krestin (Gabriel); P.W.J.C. Serruys (Patrick); P.P.T. de Jaegere (Peter)

    2010-01-01

    textabstractAimsTo evaluate the effects of applying current sizing guidelines to different multislice computer tomography (MSCT) aortic annulus measurements on Corevalve (CRS) size selection.Methods and resultsMultislice computer tomography annulus diameters [minimum: Dmin; maximum: Dmax; mean: Dmea

  5. Effect of object location on the density measurement in cone-beam computed tomography versus multislice computed tomography.

    Science.gov (United States)

    Eskandarloo, Amir; Abdinian, Mehrdad; Salemi, Fatemeh; Hashemzadeh, Zahra; Safaei, Mehran

    2012-12-01

    Bone density measurement in a radiographic view is a valuable method for evaluating the density of bone quality before performing some dental procedures such as, dental implant placements. It seems that Cone-Beam Computed Tomography (CBCT) can be used as a diagnostic tool for evaluating the density of the bone, prior to any treatment, as the reported radiation dose in this method is minimal. The aim of this study is to investigate the effect of object location on the density measurement in CBCT versus Multislice computed tomography (CT). In an experimental study, three samples with similar dimensions, but different compositions, different densities (Polyethylene, Polyamide, Polyvinyl Chloride), and three bone pieces of different parts of the mandibular bone were imaged in three different positions by CBCT and Multislice CT sets. The average density value was computed for each sample in each position. Then the data obtained from each CBCT was converted to a Hounsfield unit and evaluated using a single variable T analysis. A P value <0.05 was considered to be significant. The density in a Multislice CT is stable in the form of a Hounsfield Number, but this density is variable in the images acquired through CBCT, and the change in the position results in significant changes in the density. In this study, a statistically significant difference (P value = 0.000) has been observed for the position of the sample and its density in CBCT in comparison to Multislice CT. Density values in CBCT are not real because they are affected by the position of the object in the machine.

  6. Multislice computed tomography angiography in the diagnosis of cardiovascular disease: 3D visualizations

    Institute of Scientific and Technical Information of China (English)

    Zhonghua Sun

    2011-01-01

    Multislice computed tomography (CT) has been widely used in clinical practice for the diagnosis of cardiovascular disease due to its reduced invasiveness and high spatial and temporal resolution.As a reliable alternative to conventional angiography,multislice CT angiography has been recognized as the method of choice for detecting and diagnosing head and neck vascular disease,abdominal aortic aneurysm,aortic dissection,and pulmonary embolism.In patients with suspected coronary artery disease,although invasive coronary angiography still remains as the gold standard technique,multislice CT angiography demonstrates high diagnostic accuracy; in selected patients,it is considered as the first-line technique.The imaging diagnosis of cardiovascular disease is based on a combination of two-dimensional (2D) and three-dimensional (3D) visualization tools to enhance the diagnostic value.This is facilitated by reconstructed visualizations which provide additional information about the extent of the disease,an accurate assessment of the spatial relationship between normal structures and pathological changes,and pre-operative planning and post-procedure follow-up.The aim of the present article is to present an overview of the diagnostic performance of various 2D and 3D CT visualizations in cardiovascular disease,including multiplanar reformation,maximum intensity projection,volume rendering,and virtual intravascular endoscopy.The recognition of the potential value of these visualizations will assist clinicians in efficiently using the muitislice CT imaging modality for the diagnostic management of patients with cardiovascular disease.

  7. Cerebral blood volume imaging by flat detector computed tomography in comparison to conventional multislice perfusion CT.

    Science.gov (United States)

    Struffert, Tobias; Deuerling-Zheng, Yu; Kloska, Stephan; Engelhorn, Tobias; Boese, Jan; Zellerhoff, Michael; Schwab, Stefan; Doerfler, Arnd

    2011-04-01

    We tested the hypothesis that Flat Detector computed tomography (FD-CT) with intravenous contrast medium would allow the calculation of whole brain cerebral blood volume (CBV) mapping (FD-CBV) and would correlate with multislice Perfusion CT (PCT). Twenty five patients were investigated with FD-CBV and PCT. Correlation of the CBV maps of both techniques was carried out with measurements from six anatomical regions from both sides of the brain. Mean values of each region and the correlation coefficient were calculated. Bland-Altman analysis was performed to compare the two different imaging techniques. The image and data quality of both PCT and FD-CBV were suitable for evaluation in all patients. The mean CBV values of FD-CBV and PCT showed only minimal differences with overlapping standard deviation. The correlation coefficient was 0.79 (p < 0.01). Bland-Altman analysis showed a mean difference of -0.077 ± 0.48 ml/100 g between FD-CBV and PCT CBV measurements, indicating that FD-CBV values were only slightly lower than those of PCT. CBV mapping with intravenous contrast medium using Flat Detector CT compared favourably with multislice PCT. The ability to assess cerebral perfusion within the angiographic suite may improve the management of ischaemic stroke and evaluation of the efficacy of dedicated therapies.

  8. Compositional volumetry of non-calcified coronary plaques by multislice computed tomography: An ex vivo feasibility study

    NARCIS (Netherlands)

    N. Bruining (Nico); J.R.T.C. Roelandt (Jos); S. Verheye (Stefan); M.W. Knaapen (Michiel); Y. Onuma (Yoshinobu); E.S. Regar (Eveline); F. Cademartiri (Filippo); S. de Winter (Sebastiaan); G.J.J. van Langenhove (Glenn); P.W.J.C. Serruys (Patrick); R. Hamers (Ronald); P.J. de Feyter (Pim)

    2009-01-01

    textabstractAims: Non-invasive quantitative compositional analysis of coronary plaque would be a major advantage to study coronary artery disease. This study explores the application to use the Hounsfield units (HU) distribution of coronary plaques imaged by multislice computed tomography-coronary

  9. Role of contrast enhanced ultrasound in detection of abdominal aortic abnormalities in comparison with multislice computed tomography

    Institute of Scientific and Technical Information of China (English)

    Dirk-André Clevert; Kerstin Schick; CHEN Min-hua; ZHU Qing-li; Maximilian Reiser

    2009-01-01

    @@ dissection;abdominal aortic aneurysm;aorto-caval fistula;inflammatory abdominal aortic aneurysm Conventional ultrasound (US) is the most widely used imaging modality in routine clinical practice worldwide.The limitations of conventional ultrasound in the detection of aortic lesions versus multi-slice computed tomography angiography (MS-CTA) are well known.

  10. Multislice computed tomography of the first rib: a useful technique for bone age assessment.

    Science.gov (United States)

    Moskovitch, Guillaume; Dedouit, Fabrice; Braga, José; Rougé, Daniel; Rousseau, Hervé; Telmon, Norbert

    2010-07-01

    Macroscopic study of the first rib has been described by Kunos et al. as an efficient method of age estimation. We retrospectively reviewed a test sample of 160 first right ribs obtained from multislice computed tomography (MSCT) clinical investigations of living individuals aged 15-30 years old. Based on the descriptions of Kunos et al., we analyzed the morphological appearance of the sternal end of the first rib on two- and three-dimensional MSCT reconstructions and defined changes in appearance in stages (from 2 to 5). We also studied the calcification and ossification of the costal cartilage as an independent feature. By statistical analysis (ANOVA), we determined for each gender the correlation between the estimated stage of the costal face, the appearance of the costal cartilage, and the documented age of the subjects. We demonstrated that MSCT of the first rib appears to be an efficient noninvasive modality for bone age estimation.

  11. ROLE OF MULTISLICE COMPUTED TOMOGRAPHY IN THE DIAGNOSIS OF POSTOPERATIVE COMPLICATIONS OF AUGMENTATION MAMMOPLASTY

    Directory of Open Access Journals (Sweden)

    A. B. Abduraimov

    2008-01-01

    Full Text Available Analysis of the findings has shown that the complex use of radiation studies allows the valid diagnosis of the complications due to aug- mentation mammoplasty to be established.Due to its high informative value, multislice computed tomographic (MSCT mammography should be used as an adjuvant in high- risk patients and when there are contraindications to magnetic resonance imaging.Bolus intravenous contrast-enhanced MSCT mammography has proved to be highly effective in differentiating scar tissue from cancer recurrences.The inclusion of this technique into the examination program for patients with the nodules of irregular shape being around the implant, detected at ultrasonography and magnetic resonance mammography, may increase the specificity of noninvasive diagnosis of cancer, thus reducing the number of excision biopsies.

  12. Computer-aided diagnosis workstation and network system for chest diagnosis based on multislice CT images

    Science.gov (United States)

    Satoh, Hitoshi; Niki, Noboru; Eguchi, Kenji; Moriyama, Noriyuki; Ohmatsu, Hironobu; Masuda, Hideo; Machida, Suguru

    2008-03-01

    Mass screening based on multi-helical CT images requires a considerable number of images to be read. It is this time-consuming step that makes the use of helical CT for mass screening impractical at present. To overcome this problem, we have provided diagnostic assistance methods to medical screening specialists by developing a lung cancer screening algorithm that automatically detects suspected lung cancers in helical CT images, a coronary artery calcification screening algorithm that automatically detects suspected coronary artery calcification and a vertebra body analysis algorithm for quantitative evaluation of osteoporosis likelihood by using helical CT scanner for the lung cancer mass screening. The function to observe suspicious shadow in detail are provided in computer-aided diagnosis workstation with these screening algorithms. We also have developed the telemedicine network by using Web medical image conference system with the security improvement of images transmission, Biometric fingerprint authentication system and Biometric face authentication system. Biometric face authentication used on site of telemedicine makes "Encryption of file" and Success in login" effective. As a result, patients' private information is protected. Based on these diagnostic assistance methods, we have developed a new computer-aided workstation and a new telemedicine network that can display suspected lesions three-dimensionally in a short time. The results of this study indicate that our radiological information system without film by using computer-aided diagnosis workstation and our telemedicine network system can increase diagnostic speed, diagnostic accuracy and security improvement of medical information.

  13. Patient dose in cardiac multislice computed tomography; Dosis a pacientes en exploraciones de tomografia computerizada cardiaca

    Energy Technology Data Exchange (ETDEWEB)

    Vicedo, A.; Santa-Olalla, I.; Corredoira, E.; Gutierrez, J.; Rey, G.; Tellez, M.

    2006-07-01

    Cardiac Multislice Computed Tomography (MSCT) is mainly used for the quantification of coronary artery calcification and for minimally invasive coronary angiography. Many physicians are not aware of the radiation doses delivered to the patient in these exams. The aim of this study is to evaluate and compare the radiation doses that are delivered to the patient during specific cardiac MSCT examinations in two different hospitals in Madrid. The volume computed tomographic dose index (CTDI vol), the dose length product (DLP), and the effective dose (E) are the most useful parameters to describe and compare radiation doses received from cardiac MSCT examinations. To calculate effective doses the spreadsheet developed by ImPACT was used. Computed tomography dose index (CTDIn) in air was measured with an ionization chamber model 20x5-2CT and dose-length product (DLP) values were obtained from the scanner consol for each examination. Results and conclusions: Effective dose values of 18,2 mSv and 24 mSv for coronary angiography were found in the two hospitals. The difference in dose is mainly due to the different mode of acquisition in the applied protocols rather than to the type of scanner used. (Author)

  14. Ureterolithiasis: classical and atypical findings on unenhanced helical computed tomography.

    Science.gov (United States)

    Vaswani, Kuldeep K; El-Dieb, Adam; Vitellas, Kenneth M; Bennett, William F; Bova, James G

    2002-03-01

    Evaluation of patients with acute flank pain using helical computed tomography (CT) is a well-accepted, rapid, and safe procedure in the emergency setting. Various primary and secondary signs are described in the literature for evaluation of these patients. Our purpose is to demonstrate both the classical findings associated with ureteral calculi on unenhanced helical CT and atypical findings and potential pitfalls. We also provide readers with a systematic approach to interpreting unenhanced helical CT scans performed for acute flank pain.

  15. Incidence of auditory ossicle luxation and petrous bone fractures detected in post-mortem multislice computed tomography (MSCT).

    Science.gov (United States)

    Hollinger, A; Christe, A; Thali, M J; Kneubuehl, B P; Oesterhelweg, L; Ross, S; Spendlove, D; Bolliger, S A

    2009-01-10

    As the auditory ossicles are difficult to display without harming them in conventional autopsies, lesions of these minute bones and the ossicular chain are regularly missed. In this study, the method of choice in clinical medicine for the examination of such lesions, namely multislice computed tomography, was applied to 100 corpses. The hereby obtained results regarding ossicle luxation and petrous bone fracture indicated that the lesions were not dependant on the amount, but rather on the type of energy inflicted to the head.

  16. Acute myocardial ischemia after aortic valve replacement: A comprehensive diagnostic evaluation using dynamic multislice spiral computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Lembcke, Alexander [Department of Radiology, Charite-Universitaetsmedizin Berlin, Freie Universitaet Berlin and Humboldt-Universitaet zu Berlin, Berlin (Germany)]. E-mail: alexander.lembcke@gmx.de; Hein, Patrick A. [Department of Radiology, Charite-Universitaetsmedizin Berlin, Freie Universitaet Berlin and Humboldt-Universitaet zu Berlin, Berlin (Germany); Enzweiler, Christian N.H. [Department of Radiology, Charite-Universitaetsmedizin Berlin, Freie Universitaet Berlin and Humboldt-Universitaet zu Berlin, Berlin (Germany); Hoffmann, Udo [Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA (United States); Klessen, Christian [Department of Radiology, Charite-Universitaetsmedizin Berlin, Freie Universitaet Berlin and Humboldt-Universitaet zu Berlin, Berlin (Germany); Dohmen, Pascal M. [Department of Cardiovascular Surgery, Charite-Universitaetsmedizin Berlin, Freie Universitaet Berlin and Humboldt-Universitaet zu Berlin, Berlin (Germany)

    2006-03-15

    We describe the case of a 72-year-old man presenting with endocarditis and clinical signs of acute myocardial ischemia after biological aortic valve replacement. A comprehensive cardiac dynamic multislice spiral computed tomography demonstrated: (1) an endocarditic vegetation of the aortic valve; (2) a subvalvular leakage feeding a paravalvular pseudoaneurysm based on an aortic root abscess with subsequent compromise of the systolic blood flow in the left main coronary artery and the resulting myocardial perfusion deficit.

  17. Establishment of multi-slice computed tomography (MSCT) reference level in Johor, Malaysia

    Science.gov (United States)

    Karim, M. K. A.; Hashim, S.; Bakar, K. A.; Muhammad, H.; Sabarudin, A.; Ang, W. C.; Bahruddin, N. A.

    2016-03-01

    Radiation doses from computed tomography (CT) are the highest and most hazardous compared to other imaging modalities. This study aimed to evaluate radiation dose in Johor, Malaysia to patients during computed tomography examinations of the brain, chest and abdomen and to establish the local diagnostic reference levels (DRLs) as are present with the current, state- of-art, multi-slice CT scanners. Survey forms were sent to five centres performing CT to obtain data regarding acquisition parameters as well as the dose information from CT consoles. CT- EXPO (Version 2.3.1, Germany) was used to validate the dose information. The proposed DRLs were indicated by rounding the third quartiles of whole dose distributions where mean values of CTDIw (mGy), CTDIvol (mGy) and DLP (mGy.cm) were comparable with other reference levels; 63, 63, and 1015 respectively for CT Brain; 15, 14, and 450 respectively for CT thorax and 16, 17, and 590 respectively for CT abdomen. The study revealed that the CT practice and dose output were revolutionised, and must keep up with the pace of introductory technology. We suggest that CTDIvol should be included in current national DRLs, as modern CTs are configured with a higher number of detectors and are independent of pitch factors.

  18. Aortic dissection or renal infarction: Multislice computed tomographic angiography can tell

    Directory of Open Access Journals (Sweden)

    Stojanović Miloš

    2012-01-01

    Full Text Available Introduction. Acute renal infarction as a consequence of renal artery occlusion often goes unrecognized, mostly due to the non-specific clinical features. A quick diagnosis, ideally within three hours of presentation, is a key to renal function recovery. Case Outline. A 62-year-old male patient was admitted with a sudden abdominal pain, right flank pain and nausea. He had a diastolic hypertension at admission and his previous medical history showed atrial fibrillation. Initial clinical diagnosis was aortic dissection. Laboratory findings included elevated lactate dehydrogenase (LDH and serum creatinine levels. There were no signs of aortic dissection or aneurismatic lesions registered during a multislice computed tomographic (MSCT angiography. However, MSCT angiography demonstrated left “upper” renal artery thrombosis and renal infarction - avascular area of the upper two thirds of the left kidney sharply demarcated from the surrounding parenchyma. Both kidneys excreted the contrast. Anticoagulant therapy was initiated, along with antiarrythmic and antihypertensive medications. The follow-up by computed tomography was performed after nine weeks, and it showed a partial revascularization of the previously affected area. Conclusion. Concomitant presence of flank/abdominal pain, an increased risk for thromboembolism and an elevated LDH suggested a possibility of renal infarction. MSCT angiography is a non-invasive and accurate method in the diagnosis of renal artery occlusion and the resulting renal infarction.

  19. Multislice computed tomography angiography in the diagnosis of coronary artery disease

    Institute of Scientific and Technical Information of China (English)

    Zhong-Hua Sun; Yan Cao; Hua-Feng Li

    2011-01-01

    Multislice Cr angiography represents one of the most exciting technological revolutions in cardiac imaging and it has been increasingly used in the diagnosis of coronary artery disease.Rapid improvements in multislice CT scanners over the last decade have allowed this technique to become a potentially effective alternative to invasive coronary angiography in patients with suspected coronary artery disease.High diagnostic value has been achieved with multisfice CT angiography with use of 64-and more slice CT scanners.In addition,multislice CT angiography shows accurate detection and analysis of coronary calcium,characterization of coronary plaques,as well as prediction of the disease progression and major cardiac events.Thus,patients can benefit from multislice CT angiography that provides a rapid and accurate diagnosis while avoiding unnecessary invasive coronary angiography procedures.The aim of this article is present an overview of the clinical applications of multislice CT angiography in coronary artery disease with a focus on the diagnostic accuracy of coronary artery disease;prognostic value of coronary artery disease with regard to the prediction of major cardiac events; detection and quantification of coronary calcium and characterization of coronary plaques.Limitations of multislice Cr angiography in coronary artery disease are also briefly discussed,and future directions are highlighted.

  20. Scanning protocol optimization and dose evaluation in coronary stenosis using multi-slices computed tomography

    Science.gov (United States)

    Huang, Yung-hui; Chen, Chia-lin; Sheu, Chin-yin; Lee, Jason J. S.

    2007-02-01

    Cardiovascular diseases are the most common incidence for premature death in developed countries. A major fraction is attributable to atherosclerotic coronary artery disease, which may result in sudden cardiac failure. A reduction of mortality caused by myocardial infarction may be achieved if coronary atherosclerosis can be detected and treated at an early stage before symptoms occur. Therefore, there is need for an effective tool that allows identification of patients at increased risk for future cardiac events. The current multi-detector CT has been widely used for detection and quantification of coronary calcifications as a sign of coronary atherosclerosis. The aim of this study is to optimize the diagnostic values and radiation exposure in coronary artery calcium-screening examination using multi-slice CT (MSCT) with different image scan protocols. The radiation exposure for all protocols is evaluated by using computed tomography dose index (CTDI) phantom measurements. We chose an optimal scanning protocol and evaluated patient radiation dose in the MSCT coronary artery screenings and preserved its expecting diagnostic accuracy. These changes make the MSCT have more operation flexibility and provide more diagnostic values in current practice.

  1. Virtual colonoscopy with multi-slice computed tomography; Virtuelle Koloskopie mit der Mehrschichtcomputertomographie. Vorlaeufige Ergebnisse

    Energy Technology Data Exchange (ETDEWEB)

    Rust, G.-F.; Eisele, O.; Reiser, M. [Institut fuer Klinische Radiologie, Klinikum Grosshadern, Muenchen Univ. (Germany); Hoffmann, J.N.; Kopp, R.; Fuerst, H. [Chirurgische Klinik und Poliklinik, Klinikum der Univ. Muenchen (Germany)

    2000-03-01

    Subject: Using multi-slice computed tomography (MSCT) large body areas can scanned with high spatial resolution. In this study, MSCT was employed for virtual colonoscopy in various pathologies of the colon. Results: Nine polyps and four of five colon carcinomas were detected using MSCT virtual colonoscopy. In three patients with ulcerative colitis virtual coloscopy revealed morphological alterations compatible with this disease. In two of four patients with multiple diverticula of the colon the true extent of the disorder could be assessed in virtual colonoscopy. (orig.) [German] Fragestellung: Die Mehrschichtcomputertomographie (MSCT) vermag, grosse Organbereiche mit hoher raeumlicher Aufloesung zu untersuchen. Daher koennen auch fuer die virtuelle Koloskopie eine bisher nicht erreichbare Ortsaufloesung und Detailtreue erwartet werden. Die ersten Ergebnisse mit der MSCT-Koloskopie bei unterschiedlichen pathologischen Veraenderungen des Kolons werden vorgestellt. Ergebnisse: 4 von 5 Kolonkarzinomen konnten mit der virtuellen Koloskopie dargestellt werden. Bei 3 Patienten wurden mit der virtuellen Koloskopie typische Veraenderungen der Colitis ulcerosa dargestellt, wovon ein Patient die konventionelle Koloskopie nicht tolerierte. Bei 9 Patienten mit Kolonpolypen stimmten die virtuelle und konventionelle Koloksopie vollstaendig ueberein. Bei 4 Patienten mit Divertikulose war mit der virtuellen Koloskopie nur in 2 Faellen der Befund vollstaendig zu sichern. (orig.)

  2. Association between epicardial fat volume and coronary plaques diagnosed by multislice computed tomography

    Directory of Open Access Journals (Sweden)

    José A. Morán Quijada

    2016-01-01

    Full Text Available Introduction: Coronary atherosclerotic disease is a major cause of death in Cuba and elsewhere. The volume of epicardial fat is considered a new cardiovascular risk factor because of its association with coronary atherogenesis.Objective: To determine, by multislice computed tomography, the association between epicardial fat volume and the presence of coronary atherosclerotic plaques.Method: A descriptive study was conducted with a universe of 130 patients with chest pain suggestive of ischemic heart disease, of which 117 were selected by opinion sampling. These patients underwent a calcium score study, a coronary angiography and a measurement of the epicardial fat volume.Results: Male patients predominated (54.7% and those aged 60-69 years (32.5%. A high volume of epicardial fat was found in 51.3% of patients, affecting 52.8% of women; 78.9% of patients with a calcium score between 100 and 399 UH had a high volume of epicardial fat, just as 71.2% of those with plaques and 100% of those with 4 or 5 plaques; 41% of patients had various types of plaque, which were mainly located in the anterior descending artery (88.1%.Conclusions: The measurement of the volume of epicardial fat is a useful tool to estimate the presence of coronary disease. When it was high, it was associated with older age, female gender and the presence of a higher calcium score, more plaques, more injuries and a greater involvement of the anterior descending artery.

  3. Comparison between cone-beam and multislice computed tomography for identification of simulated bone lesions

    Energy Technology Data Exchange (ETDEWEB)

    Gaia, Bruno Felipe [University of Sao Paulo (USP), SP (Brazil). Dental School. Stomatology Dept.; Sales, Marcelo Augusto Oliveira de [University of Paraiba (UFPB), Joao Pessoa, PB (Brazil). Dental School. Dept. of Radiology; Perrella, Andreia; Fenyo-Pereira, Marlene; Cavalcanti, Marcelo Gusmao Paraiso, E-mail: mgpcaval@usp.b [University of Sao Paulo (USP), SP (Brazil). Dental School. Dept. of Radiology

    2011-07-15

    There are many studies that compare the accuracy of multislice (MSCT) and cone beam (CBCT) computed tomography for evaluations in the maxillofacial region. However, further studies comparing both acquisition techniques for the evaluation of simulated mandibular bone lesions are needed. The aim of this study was to compare the accuracy of MSCT and CBCT in the diagnosis of simulated mandibular bone lesions by means of cross sectional images and axial/MPR slices. Lesions with different dimensions, shape and locularity were produced in 15 dry mandibles. The images were obtained following the cross sectional and axial/MPR (Multiplanar Reconstruction) imaging protocols and were interpreted independently. CBCT and MSCT showed similar results in depicting the percentage of cortical bone involvement, with great sensitivity and specificity (p < 0.005). There were no significant intra- or inter-examiner differences between axial/MPR images and cross sectional images with regard to sensitivity and specificity. CBCT showed results similar to those of MSCT for the identification of the number of simulated bone lesions. Cross sectional slices and axial/MPR images presented high accuracy, proving useful for bone lesion diagnosis. (author)

  4. Multi-slice computed tomography urography after diuretic injection in children with urinary tract dilatation

    Energy Technology Data Exchange (ETDEWEB)

    Kosucu, P.; Ahmetoglu, A.; Imamoglu, M.; Cay, A.; Ozdemir, O.; Dinc, H.; Kosucu, M.; Sari, A.; Saruhan, H.; Gumele, H.R. [Farabi Hospital, Trabzon (Turkey). Dept. of Radiology

    2004-02-01

    To evaluate the potential use of multi-slice computed tomography urography (MSCTU) after diuretic injection in children with urinary tract dilatation. MSCTU was performed in 19 patients (11 boys, 8 girls, mean age 5.4 years) with suspicion of urinary tract obstruction and dilatation. Furosemide, 1 mg/kg, was injected 3 min before contrast material administration and followed by a bolus of 30 ml of physiologic saline solution immediately after application of contrast material. Excretory-phase images were obtained through the abdomen and pelvis beginning 10 min after initiation of the injection of contrast material. Maximum intensity projection (MIP) and volume rendering (VR) images were post-processed to obtain urographic views. MSCTU revealed pathology in 16 of 19 patients, while 3 patients had normal findings. Ureteropelvic obstruction was found in 4 patients, obstructive megaureter in 8. Both ureteropelvic obstruction and obstructive megaureter were disclosed in 1 patient, partial ureteral duplication in 1 patient, and both complete ureteral duplication and ureterocele in 2 patients. In all patients, MIP and VR images could satisfactorily show the pathologies of the urinary tract. The estimated effective average doses of MSCTU were higher than IVU. Preliminary results of furosemide-enhanced MSCTU demonstrated consistently dilated urinary tracts, obstruction levels, and underlying pathologies better than US and IVU.

  5. Multislice computed tomography: angiographic emulation versus standard assessment for detection of coronary stenoses

    Energy Technology Data Exchange (ETDEWEB)

    Schnapauff, Dirk; Hamm, Bernd; Dewey, Marc [Humboldt-Universitaet zu Berlin, Department of Radiology, Charite - Universitaetsmedizin Berlin, Chariteplatz 1, P.O. Box 10098, Berlin (Germany); Duebel, Hans-Peter; Baumann, Gert [Charite - Universitaetsmedizin Berlin, Department of Cardiology, Berlin (Germany); Scholze, Juergen [Charite - Universitaetsmedizin Berlin, Charite Outpatient Centre, Berlin (Germany)

    2007-07-15

    The present study investigated angiographic emulation of multislice computed tomography (MSCT) (catheter-like visualization) as an alternative approach of analyzing and visualizing findings in comparison with standard assessment. Thirty patients (120 coronary arteries) were randomly selected from 90 prospectively investigated patients with suspected coronary artery disease who underwent MSCT (16-slice scanner, 0.5 mm collimation, 400 ms rotation time) prior to conventional coronary angiography for comparison of both approaches. Sensitivity and specificity of angiographic emulation [81% (26/32) and 93% (82/88)] were not significantly different from those of standard assessment [88% (28/32) and 99% (87/88)], while the per-case analysis time was significantly shorter for angiographic emulation than for standard assessment (3.4 {+-} 1.5 vs 7.0 {+-} 2.5 min, P < 0.001). Both interventional and referring cardiologists preferred angiographic emulation over standard curved multiplanar reformations of MSCT coronary angiography for illustration, mainly because of improved overall lucidity and depiction of sidebranches (P < 0.001). In conclusion, angiographic emulation of MSCT reduces analysis time, yields a diagnostic accuracy comparable to that of standard assessment, and is preferred by cardiologists for visualization of results. (orig.)

  6. Evaluation of exposure dose reduction in multislice CT coronary angiography (MS-CTA) with prospective ECG-gated helical scan

    Science.gov (United States)

    Ota, Takamasa; Tsuyuki, Masaharu; Okumura, Miwa; Sano, Tomonari; Kondo, Takeshi; Takase, Shinichi

    2008-03-01

    A novel low-dose ECG-gated helical scan method to investigate coronary artery diseases was developed. This method uses a high pitch for scanning (based on the patient's heart rate) and X-rays are generated only during the optimal cardiac phases. The dose reduction was obtained using a two-level approach: 1) To use a 64-slice CT scanner (Aquilion, Toshiba, Otawara, Tochigi, Japan) with a scan speed of 0.35 s/rot. to helically scan the heart at a high pitch based on the patient's heart rate. By changing the pitch from the conventional 0.175 to 0.271 for a heart rate of 60 bpm, the exposure dose was reduced to 65%. 2) To employ tube current gating that predicts the timing of optimal cardiac phases from the previous cardiac cycle and generates X-rays only during the required cardiac phases. The combination of high speed scanning with a high pitch and appropriate X-ray generation only in the cardiac phases from 60% to 90% allows the exposure dose to be reduced to 5.6 mSv for patients with a heart rate lower than 65 bpm. This is a dose reduction of approximately 70% compared to the conventional scanning method recommended by the manufacturer when segmental reconstruction is considered. This low-dose protocol seamlessly allows for wide scan ranges (e.g., aortic dissection) with the benefits of ECG-gated helical scanning: smooth continuity for longitudinal direction and utilization of data from all cardiac cycles.

  7. Differentiation of pyogenic hepatic abscesses from malignant mimickers using multislice-based texture acquired from contrast-enhanced computed tomography

    Institute of Scientific and Technical Information of China (English)

    Shi-Teng Suo; Zhi-Guo Zhuang; Meng-Qiu Cao; Li-Jun Qian; Xin Wang; Run-Lin Gao; Yu Fan; Jian-Rong Xu

    2016-01-01

    BACKGROUND: Pyogenic hepatic abscess may mimic prima-ry or secondary carcinoma of the liver on contrast-enhanced computed tomography (CECT). The present study was to ex-plore the usefulness of the analysis of multislice-based texture acquired from CECT in the differentiation between pyogenic hepatic abscesses and malignant mimickers. METHODS: This retrospective study included 25 abscesses in 20 patients and 33 tumors in 26 subjects who underwent CECT. To make comparison, we also enrolled 19 patients with hepatic single simple cyst. The images from CECT were ana-lyzed using a Laplacian of Gaussian band-pass iflter (5 iflter levels with sigma weighting ranging from 1.0 to 2.5). We also quantiifed the uniformity, entropy, kurtosis and skewness of the multislice-based texture at different sigma weightings. Sta-tistical signiifcance for these parameters was tested with one-way ANOVA followed by Tukey honestly signiifcant difference (HSD) test. Diagnostic performance was evaluated using the receiver operating characteristic (ROC) curve analysis. RESULTS: There were signiifcant differences in entropy and uniformity at all sigma weightings (P CONCLUSION: Multislice-based texture analysis may be use-ful for differentiating pyogenic hepatic abscesses from malig-nant mimickers.

  8. Multislice computed tomography urography in the diagnosis of urinary tract diseases

    Directory of Open Access Journals (Sweden)

    Nikolić Olivera

    2011-01-01

    Full Text Available Background/Aim. Multislice computed tomography (MSCT has triggered considerable changes in uroradiological imaging. The aim of this study was to establish the place of MSCT urography (MSCTU in comparison with intravenous urography (IVU and to determine the sensitivity and specificity of MSCT in the evaluation of urothelial abnormalities. Methods. This prospective study included 120 patients with a high clinical suspicion of urinary tract diseases divided into two groups. The group I consisted of 60 patients with macroscopic hematuria, bladder carcinoma and malignant pelvic tumors after radiotherapy or operation. They underwent both IVU and MSCTU. The group II included 60 patients (≥ 40 years old with retroperitoneal and malignant pelvic tumors, complicated pyelonephritis, microscopic hematuria, acute urinary tract obstruction (without visible calculi on unenhanced scans, and they were submitted to computed tomography with additional scan phase enabling MSCTU. Results. Compared with IVU, MSCTU is more sensitive for the detection of urinary tract diseases (parenchymal changes, renal tumors, urolithiasis, fibrosis and extraurinary processes. MSCTU is more specific than IVU for renal parenchymal abnormalities, tumors of the excretory system, urolithiasis, bladder tumors, fibrosis and extraurinary diseases. MSCTU is equally sensitive, but more specific for hydronephrosis compared to MSCT. The diagnosis made by the use of MSCTU in patients with macroscopic and microscopic hematuria and with obstruction not caused by stones, perfectly comply with operative findings and histological diagnosis. Conclusion. The obtained results support MSCTU to be the modality of choice in the diagnostic algorithm of patients with macroscopic hematuria and in the evaluation of microscopic hematuria and unexplained obstruction of the urinary tract. The only remaining role for IVU in our institution is imaging of the upper urinary tract in patients with hematuria under

  9. Axial resolution and the value of interpolating scan in multislice positron computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Senda, M.; Yonekura, Y.; Tamaki, N.; Tanaka, Y.; Komori, M.; Minato, K.; Torizuka, K.

    1985-05-01

    The authors have calculated the aperture function of a positron computed tomograph (PCT) with computer simulation and evaluated both theoretically and experimentally the axial resolution of a multislice PCT, Positologica III, which has 7 slices at the interval of 16mm. The axial point spread function (PSF) was approximately a triangle at or near the center of the field and the sensitivity for the slice decreased significantly as the source moved away off the image plane. Accordingly there are low sensitivity areas between an in-plane and the adjacent cross-plane. In experiments using a myocardial phantom, a small myocardial defect of 1cm diameter could not be detected when dropped into the gap between slices, although the machine had sufficiently high resolution to deliniate it if it was on the image plane. When long-axis images of the ''myocardium'' were reconstructed three-dimensionally from the images obtained in single object position, the ''inferior wall'' dropped into the gap and disappeared. In clinical myocardial scan with N-13 labeled ammonia in a normal volunteer, a false positive defect appeared in the inferior wall. However, when the object is slided half the slice interval to perform the ''interpolating'' scan and the two sets of images were interlaced with each other, no artifacts appeared. These results have suggested that the invisible regions between slices may be clinically significant if the object is thin enough in z-axis. In order to fill up the gaps between slices, it is valuable to perform the interpolating scan.

  10. A comparative evaluation of Cone Beam Computed Tomography (CBCT) and Multi-Slice CT (MSCT)

    Energy Technology Data Exchange (ETDEWEB)

    Liang Xin, E-mail: Xin.Liang@med.kuleuven.b [Oral Imaging Centre, School of Dentistry, Oral Pathology and Maxillofacial Surgery, Faculty of Medicine, Catholic University of Leuven (Belgium); College of Stomatology, Dalian Medical University (China); Jacobs, Reinhilde, E-mail: Reinhilde.Jacobs@uz.kuleuven.b [Oral Imaging Centre, School of Dentistry, Oral Pathology and Maxillofacial Surgery, Faculty of Medicine, Catholic University of Leuven (Belgium); Hassan, Bassam, E-mail: b.hassan@acta.n [Department of Oral Radiology, Academic Centre for Dentistry Amsterdam (ACTA), Amsterdam (Netherlands); Li Limin, E-mail: Limin.Li@uz.kuleuven.b [Department of Paediatric Dentistry and Special Dental Care, School of Dentistry, Oral Pathology and Maxillofacial Surgery, Faculty of Medicine, Catholic University of Leuven (Belgium); Pauwels, Ruben, E-mail: Ruben.Pauwels@med.kuleuven.b [Oral Imaging Centre, School of Dentistry, Oral Pathology and Maxillofacial Surgery, Faculty of Medicine, Catholic University of Leuven (Belgium); Corpas, Livia, E-mail: LiviaCorpas@gmail.co [Oral Imaging Centre, School of Dentistry, Oral Pathology and Maxillofacial Surgery, Faculty of Medicine, Catholic University of Leuven (Belgium); Souza, Paulo Couto, E-mail: Paulo.CoutoSouza@med.kuleuven.b [Oral Imaging Centre, School of Dentistry, Oral Pathology and Maxillofacial Surgery, Faculty of Medicine, Catholic University of Leuven (Belgium); Martens, Wendy, E-mail: wendy.martens@uhasselt.b [Department of Basic Medical Sciences, Faculty of Medicine, University of Hasselt, Diepenbeek (Belgium); Shahbazian, Maryam, E-mail: Maryam.Shahbazian@student.kuleuven.b [Oral Imaging Centre, School of Dentistry, Oral Pathology and Maxillofacial Surgery, Faculty of Medicine, Catholic University of Leuven (Belgium); Alonso, Arie, E-mail: ariel.alonso@uhasselt.b [Department of Biostatistics and Statistical Bioinformatics, Universiteit Hasselt (Belgium)

    2010-08-15

    Aims: To compare image quality and visibility of anatomical structures in the mandible between five Cone Beam Computed Tomography (CBCT) scanners and one Multi-Slice CT (MSCT) system. Materials and methods: One dry mandible was scanned with five CBCT scanners (Accuitomo 3D, i-CAT, NewTom 3G, Galileos, Scanora 3D) and one MSCT system (Somatom Sensation 16) using 13 different scan protocols. Visibility of 11 anatomical structures and overall image noise were compared between CBCT and MSCT. Five independent observers reviewed the CBCT and the MSCT images in the three orthographic planes (axial, sagittal and coronal) and assessed image quality on a five-point scale. Results: Significant differences were found in the visibility of the different anatomical structures and image noise level between MSCT and CBCT and among the five CBCT systems (p = 0.0001). Delicate structures such as trabecular bone and periodontal ligament were significantly less visible and more variable among the systems in comparison with other anatomical structures (p = 0.0001). Visibility of relatively large structures such as mandibular canal and mental foramen was satisfactory for all devices. The Accuitomo system was superior to MSCT and all other CBCT systems in depicting anatomical structures while MSCT was superior to all other CBCT systems in terms of reduced image noise. Conclusions: CBCT image quality is comparable or even superior to MSCT even though some variability exists among the different CBCT systems in depicting delicate structures. Considering the low radiation dose and high-resolution imaging, CBCT could be beneficial for dentomaxillofacial radiology.

  11. SPECTRUM OF FUNCTIONING ISLET CELL TUMOR ON MULTISLICE COMPUTED TOMOGRAPHY: EXPERIENCE ON 70 PATIENTS

    Institute of Scientific and Technical Information of China (English)

    Hua-dan Xue; Zheng-yu Jin; Wei Liu; Hao Sun; Reto Merges; Xuan Wang; Xiao-na Zhang; Yun Wang; Wen-min Zhao; Jiu-hong Chen

    2008-01-01

    Objective To review experience in preoperative detection of islet cell tumors using multislice computed tomo-graphy (MSCT) and summarize various imaging features of functioning islet cell tumors on enhanced MSCT.Methods Seventy patients with clinical or pathological diagnosis of functioning pancreatic islet cell tumor between October 2003 and February 2007 were included in this retrospective study. Seventy-four enhanced MSCT scans in these patients were identified. All MSCT scans were interpreted by two experienced radiologists by consensus interpretation.Surgery and pathology reports were used to confirm the diagnosis, localization, and size of tumors.Results Totally, 73 functioning islet cell tumors including 65 benign insulinomas, 2 benign giucagnnomas, 3 ma-lignant insulinomas, and 3 malignant glucagonomas were pathologically diagnosed. Tumors in only two cases were not found by MSCT. In 67 benign lesions, 32 showed typical enhancement style, 21 showed prolonged enhancement in por-tal venous phase, 4 showed delayed enhancement, 4 had iso-dense enhancement with normal pancreatic parenchyma, 2 had no enhancement at all in arterial phase and portal venous phase, and 4 had inhomogeneous enhancement with necro-sis or cyst-formation. Patchy or spotty calcifications were found in 3 of the 67 tumors. In 6 malignant islet cell tumors,vessel invasion (2/6) and bowel invasion (1/6) were seen. Different enhancement patterns were shown. All hepatic metastases showed hyper-enhancement during their arterial phase.Conelusions Pancreatic islet cell tumor may display a wide spectrum of presentations in MSCT. Umors with unu-sual appearances often present as diagunstie challenges. Non-contrast and post-contrast multiphase scans are recommen-ded for the localization of functioning islet cell tumors.

  12. Multi-slice computed tomography for diagnosis of combined thoracoabdominal injury

    Directory of Open Access Journals (Sweden)

    Liu Jun

    2015-07-01

    Full Text Available Purpose: To investigate the diagnostic value of multi-slice computed tomography (MSCT for combined thoracoabdominal injury. Methods: A retrospective study was conducted to analyze the clinical data and MSCT images of 68 patients who sustained a combined thoracoabdominal injury associated with diaphragm rupture, and 18 patients without diaphragm rupture. All the patients were admitted and treated in the Chongqing Emergency Medical Center (a level I trauma center between July 2005 and February 2014. There were 71 males and 15 females with a mean age of 39.1 years (range 13e88 years. Among the 86 patients, 40 patients suffered a penetrating injury, 46 suffered a blunt injury as a result of road traffic accident in 21 cases, fall from a height in 16, and crushing injury in 9. The MSCT images were retrospectively reviewed by two radiologists. The results of CT diagnosis were compared with surgical findings and/or follow-up results. Results: Among the 86 cases, diaphragm discontinuity was found in 29 cases, segmental nonrecognition of the diaphragm in 14, diaphragmatic hernia in 21, collar sign in 14, dependent viscera sign in 18, elevated abdominal organs in 21, bowel wall thickening and/or hematoma in 6, and pneumoperitoneum in 8. CT diagnostic accuracy for diaphragm rupture was 88.4% in the right side and 90.7% in the left side. CT diagnostic accuracy for hemopneumothorax, pulmonary contusion, mediastinal hemorrhage, kidney and adrenal gland injuries was 100%, while for liver, spleen and pancreas injuries was 96.5%, 96.5%, 94.2% respectively. Conclusion: To reach an early diagnosis of combined thoracoabdominal injury, surgeons and radiologists should be familiar with all kinds of images which might show signs of diaphragm rupture, such as diaphragm discontinuity, segmental nonrecognition of the diaphragm, dangling diaphragm sign, diaphragm herniation, collar sign, dependent viscera sign, and elevated abdominal organs.

  13. Color doppler ultrasonography and multislice computer tomography angiography in carotid plaque detection and characterization

    Directory of Open Access Journals (Sweden)

    Vučaj-Ćirilović Viktorija

    2011-01-01

    Full Text Available Beckground/Aim. Cerebrovascular diseases are the third leading cause of mortality in the world, following malignant and cardiovascular diseases. Therefore, their timely and precise diagnostics is of great importance. The aim of this study was to compare duplex scan Color Doppler ultrasonography (CDU with multislice computed tomography angiography (MSCTA in detection of morphological and functional disorders at extracranial level of carotid arteries. Methods. The study included 75 patients with 150 carotid arteries examined in the period from January 2008 to April 2009. The patients were firstly examined by CDU, then MSCTA, followed by the surgery of extracranial segment of carotid arteries. In 10 patients, the obtained material was referred for histopathological (HP examination. We used both CDU and MSCT in the analysis of: plaque surface, plaque structure, degree of stenosis, and the presence of intraplaque hemorrhage. Results. The results obtained by CDU and MSCTA were first compared between themselves, and then to intraoperative findings. Retrospective analysis showed that MSCTA is more sensitive than CDU in assessment of plaque surface (for smooth plaques CDU 89% : MSCTA 97%; for plaques with irregular surface CDU 75% : MSCTA 87%; for ulcerations CDU 54% : MSCTA 87%. Regarding determination of plaque structure (mixed plaque CDU 66% : MSCTA 70%; correlation with HP findings CDU 94% : MSCTA 96% and localization (CDU 63% : MSCTA 65%, and in terms of sensitivity and specificity, both methods showed almost the same results. Also, there is no statistical difference between these two methods for the degree of stenosis (CDU 96% : MSCTA 98%. Conclusion. Atherosclerotic disease of extracranial part of carotid arteries primarily affects population of middle-aged and elderly, showing more associated risk factors. Sensitivity and specificity of CDU and MSCTA regarding plaque composition, the degree of stenosis and plaque localization are almost the same

  14. Evaluation of Blood Flow Patterns of Solitary Pulmonary Nodules with Dynamic Multi-slice Spiral Computed Tomography

    Institute of Scientific and Technical Information of China (English)

    LIShenjiang; XIAOXiangsheng; LIHuimin; LIUShiyuan; LIChengzhou; ZHANGChenshi; TAOZhiwei; YANGChunshan

    2004-01-01

    To evaluate the efficacy of dynamic multi-slice spiral computed tomography (MSCT) for providing quantitative information about blood flow patterns of solitary pulmonary nodules (SPNs) and differentiating solitary pulmonary nodules (SPNs). Methods: 37 patients with SPNs (diameter0.01). SFN-to-aorta ratio in inflammatory SPNs (20.78%±4.14) was significantly higher than that in benign (2.00%±2.26) and malig nant (14.63%±6.22) SPNs (P0.01). Conclusion: MSCT provides quantitative information about blood flow patterns of solitary pulmonary nodules (SPNs) and is applicable diagnostic method for differentiating SPNs.

  15. Decreased Diagnostic Accuracy of Multislice Coronary Computed Tomographic Angiography in Women with Atypical Angina Symptoms

    Institute of Scientific and Technical Information of China (English)

    Wen-Ying Jin; Xiu-Juan Zhao; Hong Chen

    2016-01-01

    Background:Multislice computed tomography (MSCT) coronary angiography (CAG) is a noninvasive technique with a reported high diagnostic accuracy for coronary artery disease (CAD).Women,more frequently than men,are known to develop atypical angina symptoms.The purpose of this study was to investigate whether the diagnostic accuracy of MSCT in women with atypical presentation differs from that in men.Methods:We enrolled 396 in-hospital patients (141 women and 255 men) with suspected or proven CAD who successively underwent both MSCT and invasive CAG.CAD was defined as any coronary stenosis of≥50% on conventional invasive CAG,which was used as the reference standard.The patients were divided into typical and atypical groups based on their symptoms of angina pectoris.The diagnostic accuracy of MSCT,including its sensitivity,specificity,negative predictive value,and positive predictive value (PPV),was calculated to determine the usefulness of MSCT in assessing stenoses.The diagnostic performance of MSCT was also assessed by constructing receiver operating characteristic (ROC) curves.Results:The PPV (91% vs.97%,x2 =5.705,P < 0.05) and diagnostic accuracy (87% vs.93%,x2 =5.093,P < 0.05) of MSCT in detecting CAD were lower in women than in men.Atypical presentation was an independent influencing factor on the diagnostic accuracy of MSCT in women (odds ratio =4.94,95% confidence intervals:1.16-20.92,Walds =4.69,P < 0.05).Compared with those in the atypical group,women with typical angina pectoris had higher PPV (98% vs.74%,x2 =17.283.P < 0.001),diagnostic accuracy (93% vs.72%,x2 =9.571,P < 0.001),and area under the ROC curve (0.91 vs.0.64,Z =2.690,P < 0.01) in MSCT diagnosis.Conclusions:Although MSCT is a reliable diagnostic modality for the exclusion of significant coronary artery stenoses in all patients,gender and atypical symptoms might have some influence on its diagnostic accuracy.

  16. Multislice helical CT (MSCT) for mid-facial trauma: optimization of parameters for scanning and reconstruction; Mehrschicht-Spiral-CT (MSCT) beim Mittelgesichtstrauma: Optimierung der Aufnahme- und Rekonstruktionsparameter

    Energy Technology Data Exchange (ETDEWEB)

    Dammert, S.; Funke, M.; Obernauer, S.; Grabbe, E. [Abt. Roentgendiagnostik I, Georg-August-Univ. Goettingen (Germany); Merten, H.A. [Abt. fuer Mund-, Kiefer- und Gesichtschirurgie, Georg-August-Univ. Goettingen (Germany)

    2002-07-01

    Purpose: To determine the optimal scan parameters in multislice helical CT (MSCT) of the facial bone complex for both axial scanning and multiplanar reconstructions. Material and Methods: An anthropomorphic skull phantom was examined with a MSCT. Axial scans were performed with continuously increasing collimations (4 x 1.25 - 4 x 2.5 mm), tube current (20 - 200 mA) and table speeds (3.75 mm/rot. and 7.5 mm/rot.). Multiplanar reconstructions in coronal and parasagittal planes with different reconstruction increment and slice thickness were evaluated in terms of image noise, contour artifacts and visualisation of anatomical structures. Results: The best image quality was obtained with a collimation of 4 x 1.25 mm and a - table speed of 3.75 mm/rot. A reconstruction increment of 0.6 mm achieved the best time to image quality relation. With these parameters the bone structures were depicted in an optimal way without artifacts. The tube current could be reduced to 50 mA without significant loss of image quality. The optimized protocol was used for regular routine examinations in patients with facial trauma (n = 66). Conclusions: Low-dose MSCT using thin collimation, low table speed and small reconstruction increments provides excellent data for both axial images and multiplanar reconstructions in patients with facial trauma. An additional examination in coronal orientation is therefore no longer necessary. (orig.) [German] Zielsetzung: Verbesserung der Aufnahme- und Rekonstruktionsparameter in der Mehrschicht Spiral-CT (MSCT) zur Untersuchung des knoechernen Mittelgesichtes in verschiedenen Ebenen. Material und Methode: Ein anthropomorphes Schaedel-Phantom wurde in axialer Schichtfuehrung mit einem MSCT untersucht, wobei die Kollimation (1,25 - 2,5 mm), der Tischvorschubfaktor (Pitch 3 - 6) und der Roehrenstrom (20 - 200 mA) systematisch variiert wurden. Aus den Volumendatensaetzen wurden jeweils koronare und parasagittale Sekundaerreformationen mit unterschiedlichen

  17. Multi-slice computed tomography assessment of bronchial compression with absent pulmonary valve

    Energy Technology Data Exchange (ETDEWEB)

    Zhong, Yu-Min; Sun, Ai-Min; Wang, Qian; Zhu, Ming; Qiu, Hai-Sheng [Shanghai Children' s Medical Center and Shanghai Jiao Tong University Medical School, Department of Radiology, Shanghai (China); Jaffe, Richard B. [Primary Children' s Medical Center, Department of Medical Imaging, Salt Lake City, UT (United States); Liu, Jin-Fen [Shanghai Children' s Medical Center, Department of Cardiothoracic Surgery, Shanghai (China); Gao, Wei [Shanghai Children' s Medical Center and Shanghai Jiao Tong University Medical School, Department of Cardiology, Shanghai (China); Berdon, Walter E. [Children' s Hospital of New York, Department of Radiology, New York, NY (United States)

    2014-07-15

    Absent pulmonary valve is a rare cardiovascular anomaly that can result in profound tracheobronchial compression. To demonstrate the advantage of multi-slice CT in diagnosing tracheobronchial compression, its severity as related to the adjacent dilated pulmonary arteries, and associated lung and cardiac lesions. We included children with absent pulmonary valve who were reviewed by multi-slice CT during a 17-year period. The number and locations of stenoses and lung lesions were noted and the severity of stenosis was categorized. The diameter of the pulmonary artery was measured and associated cardiac defects were demonstrated. Thirty-one children (14 girls and 17 boys) were included. Of these, 29 had ventricular septal defect and 2 had an intact ventricular septum. Twenty-nine children (94%) had tracheobronchial compression, judged to be mild in nine children (31%), moderate in 10 (34%) and severe in 10 (34%). The different locations of the stenosis (carina, main bronchi, lobar and segmental bronchi) were observed. And the number and location of lung lesions demonstrated that the right middle and left upper and lower lobes were often affected. The diameter of the pulmonary artery in these children was well above normal published values, and Spearman rank correlation analysis showed a correlation between the size of the pulmonary artery and the severity of the tracheobronchial stenosis. Nineteen children (61%) underwent surgery and 4 of these children had a multi-slice CT post-operative follow-up study. Absent pulmonary valve can cause significant morbidity and mortality in children. Multi-slice CT can accurately depict areas of tracheobronchial compression, associated lung lesions and cardiac defects, helping to direct the surgeon. (orig.)

  18. Helical computed tomography in the assessment of abdominal aortic pathology

    Energy Technology Data Exchange (ETDEWEB)

    Vicaretti, M.; Young, N.; Jenkins, J.; Fletcher, J. [Westmead Hospital, Westmead, NSW (Australia)

    1997-05-01

    A pilot study was undertaken to evaluate the role of helical computed tomography in the assessment of abdominal aortic pathology. A total of 17 patients underwent intra-arterial digital subtraction angiography (IADSA) and helical computed tomography, with eight patients undergoing subsequent operative intervention. A comparison of radiological findings between IADSA and helical computed tomography (CT) was made and, where applicable, a comparison was made with operative findings. Pathology included abdominal aortic aneurysm (AAA) (n=12), thoraco abdominal aneurysm (n=2) and dissection (n=1), graft distension following AAA repair (n=1) and plaque haemorrhage in the distal aorta following percutaneous transluminal angioplasty (PTA) of the iliac artery (n=1). Planned operative management as based on pre-operative helical CT imaging findings, in particular with reference to the type of graft used (straight or bifurcated) was not changed at operation. Our findings on helical CT in regards to AAA, thoraco-abdominal aneurysm and dissection correlated well with angiography and surgery findings. (authors). 26 refs., 2 tabs., 5 figs.

  19. Hepatic focal nodular hyperplasia in children: Imaging features on multi-slice computed tomography

    Institute of Scientific and Technical Information of China (English)

    Qing-Yu Liu; Wei-Dong Zhang; Dong-Ming Lai; Ying Ou-yang; Ming Gao; Xiao-Feng Lin

    2012-01-01

    AIM:To retrospectively analyze the imaging features of hepatic focal nodular hyperplasia (FNH) in children on dynamic contrast-enhanced multi-slice computed tomography (MSCT) and computed tomography angiography (CTA) images.METHODS:From September 1999 to April 2012,a total of 218 cases of hepatic FNH were confirmed by either surgical resection or biopsy in the Sun Yat-sen Memorial Hospital of Sun Yat-sen University and the Cancer center of Sun Yat-sen University,including 12 cases (5.5%) of FNH in children (age ≤ 18 years old).All the 12 pediatric patients underwent MSCT.We retrospectively analyzed the imaging features of FNH lesions,including the number,location,size,margin,density of FNH demonstrated on pre-contrast and contrastenhanced computed tomography (CT) scanning,central scar,fibrous sepia,pseudocapsule,the morphology of the feeding arteries and the presence of draining vessels (portal vein or hepatic vein).RESULTS:All the 12 pediatric cases of FNH had solitary lesion.The maximum diameter of the lesions was 4.0-12.9 cm,with an average diameter of 5.5 ± 2.5 cm.The majority of the FNH lesions (10/12,83.3%) had well-defined margins.Central scar (10/12,83.3%) and fibrous septa (11/12,91.7%) were commonly found in children with FNH.Central scar was either isodense (n =7) or hypodense (n =3) on pre-contrast CT images and showed progressive enhancement in 8 cases in the equilibrium phase.Fibrous septa were linear hypodense areas in the arterial phase and isodense in the portal and equilibrium phases.Pseudocapsule was very rare (1/12,8.3%) in pediatric FNH.With the exception of central scars and fibrous septa within the lesions,all 12 cases of pediatric FNH were homogenously enhanced on the contrast-enhanced CT images,significantly hyperdense in the arterial phase (12/12,100.0%),and isodense in the portal venous phase (7/12,58.3%) and equilibrium phase (11/12,91.7%).Central feeding arteries inside the tumors were observed on CTA images for all

  20. A comparative evaluation of Cone Beam Computed Tomography (CBCT) and Multi-Slice CT (MSCT) Part I. On subjective image quality

    NARCIS (Netherlands)

    Liang, X.; Jacobs, R.; Hassan, B.; Li, L.M.; Pauwels, R.; Corpas, L.; Souza, P.C.; Martens, W.; Alonso, A.; Lambrichts, I.

    2010-01-01

    Aims: To compare image quality and visibility of anatomical structures in the mandible between five Cone Beam Computed Tomography (CBCT) scanners and one Multi-Slice CT (MSCT) system. Materials and methods: One dry mandible was scanned with five CBCT scanners (Accuitomo 3D, i-CAT, NewTom 3G, Galileo

  1. A comparative evaluation of Cone Beam Computed Tomography (CBCT) and Multi-Slice CT (MSCT). Part II: On 3D model accuracy

    NARCIS (Netherlands)

    Liang, X.; Lambrichts, I.; Sun, Y.; Denis, K.; Hassan, B.; Li, L.; Pauwels, R.; Jacobs, R.

    2010-01-01

    Aim: The study aim was to compare the geometric accuracy of three-dimensional (3D) surface model reconstructions between five Cone Beam Computed Tomography (CBCT) scanners and one Multi-Slice CT (MSCT) system. Materials and methods: A dry human mandible was scanned with five CBCT systems (NewTom 3G,

  2. Value of multi-slice helical CT for diagnosing colonic diverticulitis%多层螺旋CT在结肠憩室炎诊断中的价值

    Institute of Scientific and Technical Information of China (English)

    万荣超; 邓德茂; 袁文昭; 陈文福; 李敏; 廖海; 陈加军

    2014-01-01

    Objective To determine the multi-slice spiral computed tomography(MSCT)features of colonic diverticulitis. Methods The clinical information and MSCT of 11 patients with pathologically confirmed colonic diverticulitis were retrospectively analyzed.Results CT showed colonic diverticula with surrounding fat stranding(10)and fecalith in the diverticula(7),pericolonic fat stranding and pneumoperitoneum(1),colon wall thickening(9),bowel perforation(5)with pneumoperitoneum(3)and hematoma(1). Conclusion MSCT displays clearly the pathological changes and complications of colonic diverticulitis.%目的:分析结肠憩室炎MSCT表现,以提高对该病的认识和诊断水平。方法回顾性分析11例经结肠镜检或手术病理证实结肠憩室炎病例的临床及MSCT资料,并结合文献复习。所有病例均作腹盆部CT平扫检查,其中2例加作CT增强检查,总结结肠憩室炎的MSCT表现特征。结果 CT表现为结肠肠壁囊袋状突出并周围脂肪密度增高10例,其中憩室内粪石7例,仅表现为肠壁周围脂肪密度增高及气腹征者1例,结肠肠壁增厚9例,憩室炎穿孔5例,其中气腹3例,合并出血1例。结论 MSCT能较好的显示结肠憩室炎病变及其并发症,对结肠憩室炎有较高的诊断价值。

  3. Efficacy of cholangiography under helical computed tomography for laparoscopic cholecystectomy

    Energy Technology Data Exchange (ETDEWEB)

    Takeuchi, Motoya; Hishiyama, Houhei [Asahikawa Red Cross Hospital, Hokkaido (Japan); Kondo, Satoshi; Katoh, Hiroyuki [Hokkaido Univ., Sapporo (Japan). Graduate School of Medicine

    2002-05-01

    Although laparoscopic cholecystectomy (LC) is known to be safe, the optimal imaging technique for examining the common bile duct and cystic duct prior to laparoscopic intervention remains controversial. The objective of this study was to evaluate the efficacy of cholangiography under helical computed tomography (helical CT cholangiography) for LC. We studied 53 consecutive patients who underwent LC carried out by the same surgeon. The data of 23 of these patients who had undergone LC before the introduction of helical CT were used as the reference standard. Among the 53 patients, 28 were prospectively randomized for preoperative biliary tract evaluation with versus without helical CT cholangiography, into a CT/+ group (n=13) and a CT/- group (n=15), respectively. Two patients were excluded from the study preoperatively. There were no significant differences in age or laboratory findings, including liver function tests or the serum amylase level before or after surgery, between the two groups. In the CT/- group, endoscopic retrograde cholangiography-related pancreatitis developed in one patient, and one patient required conversion to open surgery. In contrast, in the CT/+ group, there were no preoperative complications and no patient required conversion to open surgery. The mean operative time was significantly shorter in the CT/+ group than in the CT/- group (P=0.0137). These findings provide evidence to support the advantages of helical CT cholangiography in relation to operative time, conversion, and procedure-related preoperative complications. (author)

  4. THE ROLE OF MULTISLICE COMPUTED TOMOGRAPHY IN THE EMERGENCY DIAGNOSIS OF THE TRACHEOBRONCHIAL INJURY AFTER ENDOTRACHEAL INTUBATION - CASE REPORT

    Directory of Open Access Journals (Sweden)

    Aleksandar Karanikolić

    2015-03-01

    Full Text Available Tracheobronchial injury (TBI is a rare complication occurring after endotracheal intubation. Treatment can be conservative for small lesions and when the patient’s condition is stable, or surgical for bigger lesions and when pneumomediastinum and/or subcutaneous emphysema threaten the patient’s life. Total thyroidectomy was performed in a 60-year-old woman with multinodular goiter. Ten hours after surgery, subcutaneous emphysema of the face and neck developed. A cervical and thoracic multislice computed tomography (MSCT confirmed subcutaneous emphysema, pneumomediastinum, and posterior wall tracheal rupture 2cm in size. The patient was treated conservatively. The MSCT imaging can be a useful method for diagnosing the location and form of tracheal injury in hemodynamically stable patients.

  5. Evaluation of aortic valve stenosis by cardiac multislice computed tomography compared with echocardiography: a systematic review and meta-analysis

    DEFF Research Database (Denmark)

    Sivertsen, Jacob; Køber, Lars Valeur; Abdulla, Jawdat

    2009-01-01

    BACKGROUND AND AIM OF THE STUDY: It has not yet been established whether multi-slice computed tomography (MSCT) is reliable for the quantification of aortic valve area (AVA) in patients with aortic valve stenosis (AVS) and simultaneously for assessment of the coronary anatomy. The study aim, via...... was concordant with planimetry by TEE, with a small bias of -0.02 (95% CI -0.16, 0.11) cm2 (p = 0.71). MSCT, when compared to invasive angiography for the detection of significant coronary stenosis, showed sensitivity, specificity and diagnostic odds ratio of 95.5% (95% CI 88-99), 81% (95% CI 75-86)%, and 53 (95...... a systematic literature review and meta-analysis, was to explore whether MSCT is a reliable method for AVA quantification, and simultaneously to assess the coronary anatomy in patients with AVS. METHODS: A comprehensive systematic literature search and meta-analysis was conducted that included 14 studies...

  6. Evaluation of aortic valve stenosis by cardiac multislice computed tomography compared with echocardiography: a systematic review and meta-analysis

    DEFF Research Database (Denmark)

    Abdulla, Jawdat; Sivertsen, Jacob Christian; Kofoed, Klaus Fuglsang;

    2009-01-01

    BACKGROUND AND AIM OF THE STUDY: It has not yet been established whether multi-slice computed tomography (MSCT) is reliable for the quantification of aortic valve area (AVA) in patients with aortic valve stenosis (AVS) and simultaneously for assessment of the coronary anatomy. The study aim, via...... a systematic literature review and meta-analysis, was to explore whether MSCT is a reliable method for AVA quantification, and simultaneously to assess the coronary anatomy in patients with AVS. METHODS: A comprehensive systematic literature search and meta-analysis was conducted that included 14 studies...... with invasive coronary angiography. RESULTS: The AVA was measured by MSCT and TTE in all 14 studies, and by TEE in four studies. The results of the meta-analyses showed that planimetry by MSCT overestimated the AVA, with a bias of 0.08 (95% CI 0.04, 0.13) cm2) (p = 0.0001) compared to TTE. The MSCT measurement...

  7. Cardiac motion extraction and characterization in multislice computed tomography; Extraction et caracterisation du mouvement cardiaque en imagerie scanner multibarrette

    Energy Technology Data Exchange (ETDEWEB)

    Simon, A

    2005-12-15

    Cardiac kinetics analysis is of a great diagnostic interest in the fight against cardiovascular pathologies. Two methods are proposed in order to estimate cardiac motion from dynamic sequences of three-dimensional volumes acquired in multislice computed tomography. These methods both lie on a feature matching process, carried out within a Markovian framework and according to a multi-resolution scheme. The first method, estimating the correspondences between pre-segmented surfaces, is dependent on the temporal coherence of this segmentation. The second method estimates the correspondences between, on the one hand, a segmented surface and, on the other hand, the original data volume corresponding to the next moment. The motion estimation and the segmentation are then carried out, on the whole sequence, during a single process. Both methods are validated on simulated and real data. (author)

  8. Three-dimensional multislice spiral computed tomographic angiography: a potentially useful tool for safer free tissue transfer to complicated regions

    DEFF Research Database (Denmark)

    Demirtas, Yener; Cifci, Mehmet; Kelahmetoglu, Osman;

    2009-01-01

    Three-dimensional multislice spiral computed tomographic angiography (3D-MSCTA) is a minimally invasive method of vascular mapping. The aim of this study was to evaluate the clinical usefulness of this imaging technique in delineating the recipient vessels for safer free tissue transfer...... to complicated regions. 3D-MSCTA was performed preoperatively in 26 patients scheduled for free tissue transfer, in whom the availability of the recipient vessels were considered to be uncertain, and 23 of these were operated on. Radiographic and operative findings regarding the availability of the recipient......-MSCTA provides a noninvasive means of preoperatively assessing recipient site vessels for anatomic variations and suitability before free tissue transfer and enables the surgeon to establish an appropriate treatment plan. But it is not 100% reliable yet and the possibility of false-positive results should...

  9. Five-year clinical and functional multislice computed tomography angiographic results after coronary implantation of the fully resorbable polymeric everolimus-eluting scaffold in patients with de novo coronary artery disease

    DEFF Research Database (Denmark)

    Onuma, Yoshinobu; Dudek, Dariusz; Thuesen, Leif

    2013-01-01

    This study sought to demonstrate the 5-year clinical and functional multislice computed tomography angiographic results after implantation of the fully resorbable everolimus-eluting scaffold (Absorb BVS, Abbott Vascular, Santa Clara, California).......This study sought to demonstrate the 5-year clinical and functional multislice computed tomography angiographic results after implantation of the fully resorbable everolimus-eluting scaffold (Absorb BVS, Abbott Vascular, Santa Clara, California)....

  10. [Role of multislice spiral computed tomography in diagnosis of spinal injuries in polytrauma patients].

    Science.gov (United States)

    Nemsadze, G; Lapiashvili, E; Urushadze, O; Gotsadze, G

    2011-11-01

    Spinal injury in poly trauma patients is serious problem, because they cause high mortality and morbidity. According to WHO statistics, there are registered 30 million cases of spinal injuries annually, 50% of them die before reaching the hospital. In last 5 years incidence of spinal traumas has increased 2.6 fold and is about one third of all spinal diseases. That is why spinal injuries remain a challenge. The purpose of our study is to assess diagnostic efficiency of multislice spiral CT in diagnosis of spinal injuries in poly trauma patients. We randomly assessed data from 200 poly trauma patients, who underwent multislice spiral CT in poly trauma mode. In 92 (46%) patients different types of spinal fractures and injuries were detected. Age distribution was 16-72 (mean age 52 years). Out of 92 patients, 9 (4.5%) had isolated trauma, 83 (41.5%) had multiple trauma. Solitary injury of spinal column was detected in 30 (32.6%) patients, 54 (58.6%) had combined spinal injuries. In spinal injury patients the most common trauma mechanism was MVC - 56 patients (60.86%), fall from height 27 (29.36%) patients, diving 5 (5.43%) patients, gun shot wound 3 (3.26%) patients, industrial injury 1 (1.08%) patients. The most common location of the injury was lumbar vertebra (55 patients), thoracic vertebra (39 patients), cervical vertebra (28 patients). After assessing MDCT and MRI results 37 patients were operated, 6 of them underwent surgical intervention urgently, 31 had delayed surgery, that was performed after treating other life threatening injuries. Indications for surgical intervention were spinal cord compression and non stable vertebral fractures. According to our study results, MDCT is the study of choice for the diagnosis of spinal injuries in poly trauma patients. It helps to detect type and extension of the bony injury and visualize fragments in the spinal canal. It is superior to other radiological studies. 3D, MIP and MPR reconstruction gives information about

  11. Multislice spiral computed tomography to determine the effects of a recruitment maneuver in experimental lung injury

    Energy Technology Data Exchange (ETDEWEB)

    Henzler, Dietrich; Rossaint, Rolf [University Hospital, RWTH Aachen, Anesthesiology Department, Aachen (Germany); Mahnken, Andreas H.; Wildberger, Joachim E.; Guenther, Rolf W. [University Hospital of the RWTH Aachen, Clinic of Diagnostic Radiology, Aachen (Germany); Kuhlen, Ralf [University Hospital of the RWTH Aachen, Operative Intensive Care Department, Aachen (Germany)

    2006-06-15

    Although recruitment of atelectatic lung is a common aim in acute respiratory distress syndrome (ARDS), the effects of a recruitment maneuver have not been assessed quantitatively. By multislice spiral CT (MSCT), we analyzed the changes in lung volumes calculated from the changes in the CT values of hyperinflated (V{sub HYP}), normally (V{sub NORM}), poorly (V{sub POOR}) and nonaerated (V{sub NON}) lung in eight mechanically ventilated pigs with saline lavage-induced acute lung injury before and after a recruitment maneuver. This was compared to single slice analysis near the diaphragm. The increase in aerated lung was mainly for V{sub POOR} and the less in V{sub NORM}. Total lung volume and intrathoracic gas increased. No differences were found for tidal volumes measured by spirometry or determined by CT. The inspiratory-expiratory volume differences were not different after the recruitment maneuver in V{sub NON} (from 62{+-}18 ml to 43{+-}26 ml, P=0.114), and in V{sub NORM} (from 216{+-}51 ml to 251{+-}37 ml, P=0.102). Single slice analysis significantly underestimated the increase in normally and poorly aerated lung. Quantitative analysis of lung volumes by whole lung MSCT revealed the increase of poorly aerated lung as the main mechanism of a standard recruitment maneuver. MSCT can provide additional information as compared to single slice CT. (orig.)

  12. Imaging of coronary artery stents using multislice computed tomography: in vitro evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Maintz, David; Juergens, Kai-Uwe; Heindel, Walter; Fischbach, Roman [Department of Clinical Radiology, University of Muenster, Albert-Schweitzer-Strasse 33, 48129 Muenster (Germany); Wichter, Thomas; Grude, Matthias [Department of Cardiology and Angiology, University of Muenster, Albert-Schweitzer-Strasse 33 48129 Muenster (Germany)

    2003-04-01

    The aim of this study was to evaluate imaging features of different coronary artery stents during multislice CT Angiography (MSCTA). Nineteen stents made of varying material (steel, nitinol, tantalum) and of varying stent design were implanted in plastic tubes with an inner diameter of 3 mm to simulate a coronary artery. The tubes were filled with iodinated contrast material diluted to 200 Hounsfield units (HU), closed at both ends and positioned in a plastic container filled with oil (-70 HU). The MSCT scans were obtained perpendicular to the stent axes (detector collimation 4 x 1 mm, table feed 2 mm/rotation, 300 mAs, 120 kV). Axial images and multiplanar reformations were evaluated regarding artifact size, lumen visibility, and intraluminal attenuation values. Artifacts characterized by artifactual thickening of the stent struts leading to apparent reduction in the lumen diameter and increased intraluminal attenuation values were observed in all cases. The stent lumen was totally obscured in the Wiktor stent, the Wallgraft stent, and the Nir Royal stent. Partial residual of the stent lumen could be visualized in all other utilized stent products (artificial lumen reductions ranged from 62% in the V-Flex stent to 94% in the Bx Velocity stent). Parts of the stent lumen can be visualized in most coronary artery stents; however, detectability of in-stent stenoses remains to be evaluated for each stent type. (orig.)

  13. Comparison of Endoscopic Ultrasonography and Multislice Spiral Computed Tomography for the Preoperative Staging of Gastric Cancer - Results of a Single Institution Study of 610 Chinese Patients

    OpenAIRE

    Xing-Yu Feng; Wei Wang; Guang-Yu Luo; Jing Wu; Zhi-Wei Zhou; Wei Li; Xiao-Wei Sun; Yuan-Fang Li; Da-Zhi Xu; Yuan-Xiang Guan; Shi Chen; You-Qing Zhan; Xiao-Shi Zhang; Guo-Liang Xu; Rong Zhang

    2013-01-01

    BACKGROUND: This study compared the performance of endoscopic ultrasonography (EUS) and multislice spiral computed tomography (MSCT) in the preoperative staging of gastric cancer. METHODOLOGY/PRINCIPAL FINDINGS: A total of 610 patients participated in this study, all of whom had undergone surgical resection, had confirmed gastric cancer and were evaluated with EUS and MSCT. Tumor staging was evaluated using the Tumor-Node-Metastasis (TNM) staging and Japanese classification. The results from ...

  14. Coronary artery bypass graft imaging using ECG-gated multislice computed tomography: Comparison with catheter angiography

    Energy Technology Data Exchange (ETDEWEB)

    Moore, R.K.G. [Cardiothoracic Centre, Liverpool (United Kingdom)]. E-mail: moore@roger.go-legend.net; Sampson, C. [Cardiothoracic Centre, Liverpool (United Kingdom); MacDonald, S. [Cardiothoracic Centre, Liverpool (United Kingdom); Moynahan, C. [Cardiothoracic Centre, Liverpool (United Kingdom); Groves, D. [National Refractory Angina Centre, Liverpool (United Kingdom); Chester, M.R. [National Refractory Angina Centre, Liverpool (United Kingdom)

    2005-09-01

    AIM: To compare the value of multislice computerized tomography (MSCT) in imaging coronary artery bypass grafts (CABGs) by direct quantitative comparison with standard invasive angiography. METHODS: Using MSCT, 50 consecutive patients who had previously undergone CABG surgery and had recently undergone invasive angiography for recurrent angina pectoris, were studied further using MSCT after intravenous injection of non-ionic contrast agent; cardiac imaging was performed during a single breath-hold. Graft anatomy was quantified, using both quantitative coronary angiography (QCA) and MSCT, by different investigators blinded to each other. Reproducibility was quantified using the standard error of the measurement expressed as a percentage in log-transformed values (CV%) and intraclass correlation (ICC). RESULTS: All 150 grafts were imaged using MSCT; only 4 patent grafts were not imaged using selective angiography. Good agreement was achieved between MSCT and QCA on assessment of proximal anastomoses (CV% 25.2, ICC 0.84), mid-vessel luminal diameter (CV% 15.5, ICC 0.91) and aneurysmal dilations (CV% 14.3). Reasonable agreement was reached on assessment of distal anastomoses (CV% 26.7, ICC 0.66) and categorization of distal run-off (ICC 0.73). Good agreement was observed for stenoses of over 50% luminal loss (CV% 8.7, ICC 0.97) but agreement on assessment of less severe lesions was poor (CV% 208.7, ICC 0.51). CONCLUSION: This study demonstrates that CABGs can be quantitatively evaluated using MSCT, and that significant lesions present in all CABG segments can be reliably identified. Agreement between MSCT and QCA for lesions of less than 50% luminal loss was poor.

  15. Myocardial bridging detection by non-invasive multislice spiral computed tomography: comparison with intravascular ultrasound

    Institute of Scientific and Technical Information of China (English)

    WANG Ming-hui; ZHANG Feng; Raimund Erbel; GE Jun-bo; SUN Ai-jun; QIAN Ju-ying; LING Qing-zhi; ZENG Meng-su; GE Lei; WANG Ke-qiang; FAN Bing; YAN Wei

    2008-01-01

    Background Invasive intravascular ultrasound (IVUS) is current dlagnostic Standard for myocardial bridging (MB).Non-invasive multislice computerized tomography coronary angiography (MSCT) technique has provided a good anatomical view of the tunnel arten/ now.Methods A total of 51 consecutive patients with atypical or typical angina scheduled for IVUS were enrolled in this study and MSCT was performed 7 days before IVUS. Coronary imaging was quantified using IVUS and MSCT. Four main vessels (left main artery (LMA), left anterior descending (LAD), left circumflex (LCX), right coronary artery (RCA)) were examined.Results Forty-one out of 51 (80%) patients received metaprolol (25 mg) before the MSCT scan and 25 of them were current beta-blocker users. The mean heart rate was (64±3) beats per minute. A total of 51 patients underwent IVUS examination (30 with MB and 21 without MB) were chosen for this study. Twenty-eight out of 30 MB cases were correctly diagnosed by MSCT and 2 patients with MB were not detected. Comparison with IVUS, the sensitivity of detection by MSCT was 93%, specificity was 100%. The lumen diameter of the tunnel artery derived from MSCT and IVUS significantly decreased from (2.9±0.3) mm to (2.4±0.4) mm (P<0.001) and from (3.3±0.3) mm to (2.6±0.5) mm (P<0.001),respectively. Minimal and maximal diameters of MB derived from MSCT were significantly smaller than those from IVUS ((2.4±0.4) mm vs (2.6±0.5) mm, P<0.05 and (2.9±0.3) mm vs (3.3±0.3) mm, P<0.05), respectively.Conclusions MSCT offers a reliable non-invasive method for MB in LAD and atherosclerosis diagnosis with diagnostic accuracy comparable with invasive IVUS.

  16. Development of a computer-generated model for the coronary arterial tree based on multislice CT and morphometric data

    Science.gov (United States)

    Fung, George S. K.; Segars, W. Paul; Taguchi, Katsuyuki; Fishman, Elliot K.; Tsui, Benjamin M. W.

    2006-03-01

    A detailed four-dimensional model of the coronary artery tree has great potential in a wide variety of applications especially in biomedical imaging. We developed a computer generated three-dimensional model for the coronary arterial tree based on two datasets: (1) gated multi-slice computed tomography (MSCT) angiographic data obtained from a normal human subject and (2) statistical morphometric data obtained from porcine hearts. The main coronary arteries and heart structures were segmented from the MSCT data to define the initial segments of the vasculature and geometrical details of the boundaries. An iterative rule-based computer generation algorithm was then developed to extend the coronary artery tree beyond the initial segmented branches. The algorithm was governed by the following factors: (1) the statistical morphometric measurements of the connectivities, lengths, and diameters of the arterial segments, (2) repelling forces from other segments and boundaries, and (3) optimality principles to minimize the drag force at each bifurcation in the generated tree. Using this algorithm, the segmented coronary artery tree from the MSCT data was optimally extended to create a 3D computational model of the largest six orders of the coronary arterial tree. The new method for generating the 3D model is effective in imposing the constraints of anatomical and physiological characteristics of coronary vasculature. When combined with the 4D NCAT phantom, a computer model for the human anatomy and cardiac and respiratory motions, the new model will provide a unique tool to study cardiovascular characteristics and diseases through direct and medical imaging simulation studies.

  17. Computer-aided diagnosis workstation and telemedicine network system for chest diagnosis based on multislice CT images

    Science.gov (United States)

    Satoh, Hitoshi; Niki, Noboru; Eguchi, Kenji; Ohmatsu, Hironobu; Kakinuma, Ryutaru; Moriyama, Noriyuki

    2009-02-01

    Mass screening based on multi-helical CT images requires a considerable number of images to be read. It is this time-consuming step that makes the use of helical CT for mass screening impractical at present. Moreover, the doctor who diagnoses a medical image is insufficient in Japan. To overcome these problems, we have provided diagnostic assistance methods to medical screening specialists by developing a lung cancer screening algorithm that automatically detects suspected lung cancers in helical CT images, a coronary artery calcification screening algorithm that automatically detects suspected coronary artery calcification and a vertebra body analysis algorithm for quantitative evaluation of osteoporosis likelihood by using helical CT scanner for the lung cancer mass screening. The functions to observe suspicious shadow in detail are provided in computer-aided diagnosis workstation with these screening algorithms. We also have developed the telemedicine network by using Web medical image conference system with the security improvement of images transmission, Biometric fingerprint authentication system and Biometric face authentication system. Biometric face authentication used on site of telemedicine makes "Encryption of file" and "Success in login" effective. As a result, patients' private information is protected. We can share the screen of Web medical image conference system from two or more web conference terminals at the same time. An opinion can be exchanged mutually by using a camera and a microphone that are connected with workstation. Based on these diagnostic assistance methods, we have developed a new computer-aided workstation and a new telemedicine network that can display suspected lesions three-dimensionally in a short time. The results of this study indicate that our radiological information system without film by using computer-aided diagnosis workstation and our telemedicine network system can increase diagnostic speed, diagnostic accuracy and

  18. Virtual multislice computed tomography cystoscopy for evaluation of urinary bladder lesions; Virtuelle MDCT-Zystoskopie bei der Detektion von Blasenlaesionen

    Energy Technology Data Exchange (ETDEWEB)

    Heinz-Peer, G.; Happel, B.; Memarsadeghi, M.; Mang, T. [Medizinische Universitaet Wien (Austria). Klinik fuer Radiodiagnostik

    2005-10-01

    The introduction of multislice computed tomography (MDCT) with the possibility of acquiring isotropic datasets has been an ideal prerequisite for development of virtual MDCT cystoscopy. Remarkable technical progress regarding post-processing of high-resolution 3D datasets as well as a considerable reduction of the time required for post-processing made it possible to introduce virtual MDCT cystoscopy into the clinical routine. 3D post-processing that often required 7-8 h when virtual endoscopy techniques were first developed can now be performed in less than 5 min after transfer of data to the 3D workstation. With the limitations and contraindications of conventional cystoscopy in mind, virtual MDCT cystoscopy may be seen as a valuable alternative to conventional cystoscopy for evaluation of hematuria. (orig.) [German] Mit der Einfuehrung der Multidetektorcomputertomographie (MDCT) und der damit verbundenen Moeglichkeit, isotrope Datensaetze zu akquirieren, ergaben sich ideale Voraussetzungen zur Entwicklung der virtuellen MDCT-Zystoskopie. Beachtliche technische Fortschritte bei der Nachbearbeitung der hochaufloesenden 3D-Datensaetze sowie eine deutliche Reduktion der Nachbearbeitungszeit haben den Einsatz der virtuellen MDCT-Zystoskopie in der klinischen Routine ermoeglicht. Waren zu Beginn der Entwicklung virtueller Endoskopietechniken 3D-Nachbearbeitungszeiten von 7-8 h keine Seltenheit, kann diese heute nach dem Datentransfer auf die Workstation in weniger als 5 min erfolgen. Unter Betrachtung der Limitationen und Kontraindikationen der konventionellen Zystoskopie kann die virtuelle MDCT-Zystoskopie als wertvolle Alternative bei der Haematurieabklaerung gesehen werden. (orig.)

  19. Correlation of coronary artery stenosis evaluation with left heart structure and function by multi-slice computed tomography.

    Science.gov (United States)

    Song, L N; Cao, A D; Niu, Y J; Liu, N

    2014-08-07

    The aim of this study was to determine the impact of multi-slice computed tomography (MSCT) evaluation of coronary artery stenosis on left heart structure and systolic function. Coronary artery CT angiography was performed in 200 patients diagnosed with coronary heart disease, and then according to the AHA coronary artery 17-segment fractionation method, the Gensini score (GS) was determined for every narrow segment, and one-stop assessment of the correlation between left heart structure and function was performed. After the grouping of GS quartiles from low to high, there were differences between different patients with regard to LVDD, LADD, LVEDV, LVESV, MM, LVEF, and FS, while no difference in SV and CO. GS showed linear negative correlation with LVEF and FS, and linear positive correlation with LVDD, LADD, LVEDV, LVESV, and MM, while no correlation with SV and CO. That is, GS of coronary artery stenosis was negatively correlated with left ventricular systolic function and positively correlated with myocardial mass. The narrower the coronary artery, the worse the cardiac function and the higher the myocardial hypertrophy. Coronary artery stenosis was one of the important causes of the decrease in left ventricular systolic function and cardiac remodeling.

  20. Correlation between skeletal trauma and energy in falls from great height detected by post-mortem multislice computed tomography (MSCT).

    Science.gov (United States)

    Weilemann, Y; Thali, M J; Kneubuehl, B P; Bolliger, S A

    2008-09-18

    Fatal falls from great height are a frequently encountered setting in forensic pathology. They present--by virtue of a calculable energy transmission to the body--an ideal model for the assessment of the effects of blunt trauma to a human body. As multislice computed tomography (MSCT) has proven not only to be invaluable in clinical examinations, but also to be a viable tool in post-mortem imaging, especially in the field of osseous injuries, we performed a MSCT scan on 20 victims of falls from great height. We hereby detected fractures and their distributions were compared with the impact energy. Our study suggests a marked increase of extensive damage to different body regions at about 20 kJ and more. The thorax was most often affected, regardless of the amount of impacting energy and the primary impact site. Cranial fracture frequency displayed a biphasic distribution with regard to the impacting energy; they were more frequent in energies of less than 10, and more than 20 kJ, but rarer in the intermediate energy group, namely that of 10-20 kJ.

  1. Computational design and characterization of a monomeric helical dinuclear metalloprotein.

    Science.gov (United States)

    Calhoun, Jennifer R; Kono, Hidetoshi; Lahr, Steven; Wang, Wei; DeGrado, William F; Saven, Jeffery G

    2003-12-12

    The de novo design of di-iron proteins is an important step towards understanding the diversity of function among this complex family of metalloenzymes. Previous designs of due ferro (DF) proteins have resulted in tetrameric and dimeric four-helix bundles having crystallographically well-defined structures and active-site geometries. Here, the design and characterization of DFsc, a 114 residue monomeric four-helix bundle, is presented. The backbone was modeled using previous oligomeric structures and appropriate inter-helical turns. The identities of 26 residues were predetermined, including the primary and secondary ligands in the active site, residues involved in active site accessibility, and the gamma beta gamma beta turn between helices 2 and 3. The remaining 88 amino acid residues were determined using statistical computer aided design, which is based upon a recent statistical theory of protein sequences. Rather than sampling sequences, the theory directly provides the site-specific amino acid probabilities, which are then used to guide sequence design. The resulting sequence (DFsc) expresses well in Escherichia coli and is highly soluble. Sedimentation studies confirm that the protein is monomeric in solution. Circular dichroism spectra are consistent with the helical content of the target structure. The protein is structured in both the apo and the holo forms, with the metal-bound form exhibiting increased stability. DFsc stoichiometrically binds a variety of divalent metal ions, including Zn(II), Co(II), Fe(II), and Mn(II), with micromolar affinities. 15N HSQC NMR spectra of both the apo and Zn(II) proteins reveal excellent dispersion with evidence of a significant structural change upon metal binding. DFsc is then a realization of complete de novo design, where backbone structure, activity, and sequence are specified in the design process.

  2. ALOHA: Automatic libraries of helicity amplitudes for Feynman diagram computations

    Science.gov (United States)

    de Aquino, Priscila; Link, William; Maltoni, Fabio; Mattelaer, Olivier; Stelzer, Tim

    2012-10-01

    We present an application that automatically writes the HELAS (HELicity Amplitude Subroutines) library corresponding to the Feynman rules of any quantum field theory Lagrangian. The code is written in Python and takes the Universal FeynRules Output (UFO) as an input. From this input it produces the complete set of routines, wave-functions and amplitudes, that are needed for the computation of Feynman diagrams at leading as well as at higher orders. The representation is language independent and currently it can output routines in Fortran, C++, and Python. A few sample applications implemented in the MADGRAPH 5 framework are presented. Program summary Program title: ALOHA Catalogue identifier: AEMS_v1_0 Program summary URL: http://cpc.cs.qub.ac.uk/summaries/AEMS_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: http://www.opensource.org/licenses/UoI-NCSA.php No. of lines in distributed program, including test data, etc.: 6094320 No. of bytes in distributed program, including test data, etc.: 7479819 Distribution format: tar.gz Programming language: Python2.6 Computer: 32/64 bit Operating system: Linux/Mac/Windows RAM: 512 Mbytes Classification: 4.4, 11.6 Nature of problem: An effcient numerical evaluation of a squared matrix element can be done with the help of the helicity routines implemented in the HELAS library [1]. This static library contains a limited number of helicity functions and is therefore not always able to provide the needed routine in the presence of an arbitrary interaction. This program provides a way to automatically create the corresponding routines for any given model. Solution method: ALOHA takes the Feynman rules associated to the vertex obtained from the model information (in the UFO format [2]), and multiplies it by the different wavefunctions or propagators. As a result the analytical expression of the helicity routines is obtained. Subsequently, this expression is

  3. Metabolic syndrome correlates intracoronary stenosis detected by multislice computed tomography in male subjects with sleep-disordered breathing

    Directory of Open Access Journals (Sweden)

    Nakanishi-Minami Tomoko

    2012-03-01

    Full Text Available Abstract Background Sleep-disordered breathing (SDB, especially obstructive sleep apnea (OSA, has frequent complications include hypertension, dyslipidemia and insulin resistance based on abdominal obesity or excess visceral fat (called Syndrome Z. OSA is a potential risk factor for cardiovascular diseases. The clinical characteristics of Japanese OSA subjects with OSA remain unclear. The present study investigated prevalence and predictive factors of intracoronary stenosis detected by multislice computed tomography (MSCT in Japanese male subjects with SDB/OSA. Findings The study (O-VFStudy subjects were 39 Japanese men with SDB/OSA who underwent all-night cardiorespiratory monitoring with fully attended polysomnography, and moreover both fat computed tomography (CT scan and 64-row MSCT coronary angiography. The prevalence of coronary stenosis in this selected population with SDB/OSA was 15%. Logistic regression analysis showed a significant relationship between age-adjusted CAD and metabolic syndrome (p p = 0.033, and lower levels of serum adiponectin (4.5 ± 0.6 versus 6.4 ± 0.6 μg/mL, p = 0.014, compared with groups without the metabolic syndrome. Conclusions The present study describes that the prevalence of greater than 50% intracoronary stenotic lesions detected by MSCT was 15% and the metabolic syndrome was correlated with intracoronary stenosis detected by MSCT in Japanese SDB/OSA subjects. Trial Registration UMIN 000002997 https://upload.umin.ac.jp/cgi-open-bin/ctr/ctr.cgi?function=brows&action=brows&type=summary&recptno=R000003633&language=E.

  4. Flat-detector computed tomography with intravenous contrast material application in experimental aneurysms: comparison with multislice CT and conventional angiography.

    Science.gov (United States)

    Struffert, Tobias; Doelken, Marc; Adamek, Edyta; Schwarz, Marc; Engelhorn, Tobias; Kloska, Stephan; Ott, Sabine; Doerfler, Arnd

    2010-05-01

    Despite limited soft tissue resolution flat-detector computed tomography (FD-CT) provides substantial superior spatial resolution in comparison with multislice computed tomography (MS-CT). This may add value in the visualization of small vascular structures if intravenous contrast application leads to substantial opacification and visibility of intracranial vessels or aneurysms. To evaluate the feasibility of visualization of vascular structures by FD-CT angiography (FD-CTA) after intravenous contrast injection compared with MS-CTA and intra-arterial digital subtracted angiography (IADSA) in an animal model. Aneurysms were created in the right common carotid artery in six New Zealand White Rabbits using the elastase technique. Imaging was performed using FD-CTA, MS-CTA (injection of 1 ml/kg body weight) and IADSA. Anonymized volume rendering reconstruction (VRT), maximum intensity projection (MIP), and multiplanar reconstruction (MPR) images were reconstructed and evaluated by two experienced reviewers for aneurysm geometry and vascular structure anatomy using standard tools of a dedicated workstation. Aneurysms could be successfully created in all animals. Measurements of aneurysm geometry (aneurysm height, width, neck width) and vascular structures (brachiocephalic trunk, carotid artery diameter and plane) were nearly identical in all three modalities. Intra- and inter-observer correlations of the different parameters showed high r values between 0.83 and 0.99. Our results show the feasibility of FD-CTA in comparison with MS-CTA and IADSA in an animal model. Despite limited soft tissue resolution, opacification of vascular structures with sufficient contrast to the surrounding structures was possible in all animals. Vascular structures appeared better delineated in FD-CTA than in MS-CTA, probably due to the superior spatial resolution.

  5. Planimetry of the aortic valve orifice area: Comparison of multislice spiral computed tomography and magnetic resonance imaging

    Energy Technology Data Exchange (ETDEWEB)

    Westermann, Yvonne; Geigenmueller, Anja; Elgeti, Thomas; Wagner, Moritz [Department of Radiology, Charite - University Medicine, Berlin (Germany); Dushe, Simon [Department of Cardiovascular Surgery, Charite - University Medicine, Berlin (Germany); Borges, Adrian C. [Department of Internal Medicine I - Cardiology, Angiology and Pneumology, Charite - University Medicine, Berlin (Germany); Dohmen, Pascal M. [Department of Cardiovascular Surgery, Charite - University Medicine, Berlin (Germany); Hein, Patrick A. [Department of Radiology, Charite - University Medicine, Berlin (Germany); Lembcke, Alexander, E-mail: Alexander.Lembcke@gmx.de [Department of Radiology, Charite - University Medicine, Berlin (Germany)

    2011-03-15

    Objective: We sought to determine the comparability of multislice computed tomography (MSCT) and magnetic resonance imaging (MRI) for measuring the aortic valve orifice area (AVA) and grading aortic valve stenosis. Materials and methods: Twenty-seven individuals, among them 18 patients with valvular stenosis, underwent AVA planimetry by both MSCT and MRI. In the subset of patients with valvular stenosis, AVA was also calculated from transthoracic Doppler echocardiography (TTE) using the continuity equation. Results: There was excellent correlation between MSCT and MRI (r = 0.99) and limits of agreement were in an acceptable range ({+-}0.42 cm{sup 2}) although MSCT yielded a slightly smaller mean AVA than MRI (1.57 {+-} 0.83 cm{sup 2} vs. 1.67 {+-} 0.98 cm{sup 2}, p < 0.05). However, in the subset of patients with valvular stenosis, the mean AVA was not different between MSCT and MRI (1.05 {+-} 0.30 cm{sup 2} vs. 1.04 {+-} 0.39 cm{sup 2}; p > 0.05). The mean AVAs on both MSCT and MRI were systematically larger than on TTE (0.88 {+-} 0.28 cm{sup 2}, p < 0.001 each). Using an AVA of 1.0 cm{sup 2} on TTE as reference, the best threshold for detecting severe-to-critical stenosis on MSCT and MRI was an AVA of 1.25 cm{sup 2} and 1.30 cm{sup 2}, respectively, resulting in an accuracy of 96% each. Conclusion: Our study specifies recent reports on the suitability of MSCT for quantifying AVA. The data presented here suggest that certain methodical discrepancies of AVA measurements exist between MSCT, MRI and TTE. However, MSCT and MRI have shown excellent correlation in AVA planimetry and similar accuracy in grading aortic valve stenosis.

  6. Global and regional left ventricular function: a comparison between gated SPECT, 2D echocardiography and multi-slice computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Henneman, Maureen M.; Bax, Jeroen J.; Holman, Eduard R. [Leiden University Medical Center, Department of Cardiology, Leiden (Netherlands); Schuijf, Joanne D.; Jukema, J.W.; Wall, Ernst E. van der [Leiden University Medical Center, Department of Cardiology, Leiden (Netherlands); The Interuniversity Cardiology Institute of the Netherlands, Utrecht (Netherlands); Stokkel, Marcel P.M. [Leiden University Medical Center, Department of Nuclear Medicine, Leiden (Netherlands); Lamb, Hildo J.; Roos, Albert de [Leiden University Medical Center, Department of Radiology, Leiden (Netherlands)

    2006-12-15

    Global and regional left ventricular (LV) function are important indicators of the cardiac status in patients with coronary artery disease (CAD). Therapy and prognosis are to a large extent dependent on LV function. Multi-slice computed tomography (MSCT) has already earned its place as an imaging modality for non-invasive assessment of the coronary arteries, but since retrospective gating to the patient's ECG is performed, information on LV function can be derived. In 49 patients with known or suspected CAD, coronary angiography with MSCT imaging was performed, in addition to gated SPECT and 2D echocardiography. LV end-diastolic and LV end-systolic volumes and LV ejection fraction were analysed with dedicated software (CMR Analytical Software System, Medis, Leiden, The Netherlands for MSCT; gated SPECT by QGS, Cedars-Sinai Medical Center, Los Angeles, CA, USA), and by the biplane Simpson's rule for 2D echocardiography. Regional wall motion was evaluated according to a 17-segment model and a three-point score system. Correlations were fairly good between gated SPECT and MSCT (LVEDV: r=0.65; LVESV: r=0.63; LVEF: r=0.60), and excellent between 2D echocardiography and MSCT (LVEDV: r=0.92; LVESV: r=0.93; LVEF: r=0.80). Agreement for regional wall motion was 95% ({kappa}=0.66) between gated SPECT and MSCT, and 96% ({kappa}=0.73) between 2D echocardiography and MSCT. Global and regional LV function and LV volumes can be adequately assessed with MSCT. Correlations with 2D echocardiography are stronger than with gated SPECT. (orig.)

  7. Accuracy of Multi-Slice Spiral Computed Tomography for Preoperative Tumor Node Metastasis (TNM) Staging of Colorectal Carcinoma.

    Science.gov (United States)

    Bai, Rong-Jie; Ren, Shao-Hua; Jiang, Hui-Jie; Li, Jin-Ping; Liu, Xiao-Cheng; Xue, Li-Ming

    2017-07-17

    BACKGROUND With the advances in imaging technologies, multi-slice spiral computed tomography (MSCT) has demonstrated superiority in the diagnosis and staging of colorectal carcinoma. In the current study, preoperative TNM staging of colorectal carcinoma by using MSCT was conducted and compared with the corresponding postoperative pathological examination findings, in order to evaluate the accuracy of preoperative MSCT for TNM staging. MATERIAL AND METHODS Combinations of biphasic or triphasic enhanced-phase MSCT scans were obtained for 76 patients with colorectal carcinoma, and the TNM stage was determined based on imaging reconstruction from various angles and perspectives to display the size, location, and affected range of tumors. The preoperative TNM stage was compared with the postoperative pathological stage, and the consistency between the 2 methods was tested by the k test using SPSS 17.0 software. RESULTS Among the different combinations of enhanced-phase MSCT scanning, triphasic MSCT imaging, comprising the arterial, portal venous, and delayed phases, showed the highest accuracy rates, at 81.6% (62/76), 82.89% (63/76), and 96.1% (73/76) for T, N, and M staging, respectively, with k values of 0.72, 0.65, and 0.56, respectively, indicating consistency with the postoperative pathological staging. CONCLUSIONS Combined MSCT scanning comprising the arterial phase, portal venous phase, and delayed phase showed satisfying consistency with the postoperative pathological analysis results for TNM staging of colorectal carcinoma. Thus, MSCT is an important clinical value for improving the accuracy of TNM staging and for planning the appropriate colorectal cancer treatment.

  8. Diagnostic accuracy of in-stent coronary restenosis detection with multislice spiral computed tomography: a meta-analysis

    Energy Technology Data Exchange (ETDEWEB)

    Hamon, Michele [University Hospital of Caen, Department of Radiology, 14033 Caen Cedex, Normandy (France); Champ-Rigot, Laure; Riddell, John W. [University Hospital of Caen, Department of Cardiology, 14033 Caen Cedex, Normandy (France); Morello, Remy [University Hospital of Caen, Department of Statistics, 14033 Caen Cedex, Normandy (France); Hamon, Martial [University Hospital of Caen, Department of Cardiology, 14033 Caen Cedex, Normandy (France); Institut Pasteur de Lille, INSERM 744, Lille (France); Centre Hospitalier Universitaire de Caen, Service des Maladies du Coeur et des Vaisseaux, 14033 Caen Cedex, Normandy (France)

    2008-02-15

    This study was designed to define the current role of multislice spiral computed tomography (MSCT) for the diagnosis of coronary in-stent restenosis using a meta-analytic process. Restenosis remains a limitation after coronary stent implantation and contributes to a substantial number of coronary re-assessments by conventional invasive coronary angiography (CA). We identified 15 studies (807 patients) evaluating in-stent restenosis by means of both MSCT ({>=}16 slices) and conventional CA until February 2007. After data extraction the analysis was performed according to a random-effects model. The analysis pooled the results from 15 studies with a total of 1,175 stents. A substantial number of unassessable stents (13%) were excluded from the analysis underscoring the shortcomings of MSCT. With this major limitation the diagnostic performance of MSCT for in-stent restenosis detection can be summarized as follows: the sensitivity and specificity were 84% [95% confidence interval (CI) 77-89%] and 91% (95% CI 89-93%), respectively, with positive and negative likelihood ratios of 12.2 (95% CI 6.6-22.6) and 0.23 (95% CI 0.17-0.31), respectively, and with a diagnostic odds ratio of 67.9 (95% CI 34.4-134.1). MSCT has shortcomings difficult to overcome in daily practice for in-stent restenosis detection and continues to have moderately high sensitivity and specificity. The diagnostic role of this emerging technology as an alternative to CA for in-stent restenosis detection remains limited. (orig.)

  9. Evaluation of early coronary graft patency after coronary artery bypass graft surgery using multislice computed tomography angiography

    Directory of Open Access Journals (Sweden)

    Raissi Kamal

    2009-12-01

    Full Text Available Abstract Background Coronary artery bypass graft (CABG surgery is the standard of care in the treatment of advanced coronary artery disease, and its long-term results are affected by the failure of bypass grafts. The aim of the present study was to evaluate the early patency rate in coronary bypass grafts. Methods A total of 107 consecutive patients who underwent CABG were included in this study. Early graft patency was evaluated via computed tomography (CT angiography in the first week after surgery. Results There were a total of 366 grafts, comprised of 250 venous grafts and 116 arterial grafts. Multi-slice CT detected acute graft occlusions in 32 (8.7% of all the grafts, including 26 (10% of the 250 venous grafts and 6 (5% of the 116 arterial grafts. The patency rates obtained were 97.3% for the left internal mammary (IMA grafts, 50% for the radial artery grafts, and 50% for the right IMA grafts. Additionally, 107 (96.4% grafts to the left anterior descending artery (LAD were classified as patent, whereas 1 (30% of the 3 grafts in the left circumflex (LCX region and 1 (50% of the 2 grafts in the right coronary artery (RCA territory were found to be occluded. In the venous category, 8 (13.7% of the 58 grafts to LAD were found to be occluded. In the LCX region, 9 (8.5% of the 106 grafts were classified as occluded, while the remaining 97 (91.5% grafts were patent. The venous grafts to RCA were occluded in 9 (10.4% of the 86 grafts. Amongst the multiple preoperative, intraoperative, and postoperative factors, pump time was significantly longer in the patients with occluded grafts than in those with patent grafts (P = 0.04. Conclusion The IMA grafts had the highest early patency rate amongst the coronary bypass grafts. However, the other arterial grafts were associated with a high rate of acute occlusions.

  10. Hemodynamic study of hepatocellular car-cinoma nodules by multi-slice spiral computed tomographic perfusion

    Institute of Scientific and Technical Information of China (English)

    马国林

    2013-01-01

    Objective To analyze the 64-slice computed tomographic(CT) perfusion parameters of hepatocellular carcinoma(HCC) nodule so as to assess the diagnostic value of hemodynamic changes of HCC nodule by this perfusion

  11. Solitary pulmonary nodules: comparison of multi-slice computed tomography perfusion study with vascular endothelial growth factor and microvessel density

    Institute of Scientific and Technical Information of China (English)

    BAI Rong-jie; CHENG Xiao-guang; QU Hui; SHEN Bao-zhong; HAN Ming-jun; WU Zhen-hua

    2009-01-01

    Background The solitary pulmonary nodule (SPN) is one of the most common findings on chest radiographs. The objectives of clinical practice are to differentiate malignant nodules from benign nodules in the least invasive way and to make a specific diagnosis. This study was aimed to evaluate the correlation between perfusion imaging features and microvessel density (MVD) and vascular endothelial growth factors (VEGF) in SPNs using multi-slice computed tomography (MSCT); and to provide the theoretical basis for SPN blood flow pattern and blood flow quantitative features.Also, the study called for the discussion of the method's clinical application value in the differential diagnosis of benign and malignant SPNs.Methods Sixty-eight patients with SPN underwent multi-location dynamic contrast enhanced (nonionic contrast material was administrated via the antecubital vein at a rate of 4 ml/s) MSCT. Precontrast and postcontrast attenuations on every scan was studied. Perfusion, peak height, and the ratio of the peak height of the SPN to that of the aorta were analyzed. Perfusion was calculated using the maximum gradient of the time-density curves (TDC) and the peak height of the aorta. The quantitative parameters (perfusion, peak height, ratio of peak height of the SPN to that of the aorta) of the blood flow pattern were compared with MVD and the VEGF expression of immunohistochemistry.Results The perfusion peak heights of malignant ((96.15±11.55) HU) and inflammatory ((101.15±8.41) HU) SPNs were significantly higher than those of benign ((47.24±9.15) HU) SPNs (P<0.05, P<0.05). Ratios of SPN-to-aorta of malignant and inflammatory SPNs were significantly higher than those of benign SPNs (P<0.05, P<0.05). No significant differences were found between the peak height and SPN-to-aorta ratio of malignant SPNs and inflammatory SPNs (P>0.05, P>0.05). The precontrast densities of inflammatory SPNs were lower than those of malignant SPNs (P<0.05).Perfusion values

  12. Virtopsy post-mortem multi-slice computed tomograhy (MSCT) and magnetic resonance imaging (MRI) demonstrating descending tonsillar herniation: comparison to clinical studies

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    Aghayev, Emin; Yen, Kathrin; Thali, Michael; Jackowski, Christian; Dirnhofer, Richard [Institute of Forensic Medicine, University of Bern, IRM-Buehlstrasse 20, 3012, Bern (Switzerland); Sonnenschein, Martin [Institute of Diagnostic Radiology, Inselspital, 3010, Bern (Switzerland); Ozdoba, Christoph [Department of Neuroradiology, Inselspital, 3010, Bern (Switzerland)

    2004-07-01

    Descending cerebellar tonsillar herniation is a serious and common complication of intracranial mass lesions. We documented three cases of fatal blunt head injury using post-mortem multi-slice computed tomography (MSCT) and magnetic resonance imaging (MRI). The results showed massive bone and soft-tissue injuries of the head and signs of high intracranial pressure with herniation of the cerebellar tonsils. The diagnosis of tonsillar herniation by post-mortem radiological examination was performed prior to autopsy. This paper describes the detailed retrospective evaluation of the position of the cerebellar tonsils in post-mortem imaging in comparison to clinical studies. (orig.)

  13. Renal lymphangiectasia: incidental finding at multislice computed tomography and literature review

    Energy Technology Data Exchange (ETDEWEB)

    Vasconcelos, Rodrigo Abdalla de; Pereira, Emanuelle Santiago [Hospital de Base do Distrito Federal (HBDF), Brasilia, DF (Brazil); Bauab Junior, Tufik [Instituto de Radiodiagnostico Rio Preto - Ultra-X and Hospital de Base de Faculdade de Medicina de Sao Jose do Rio Preto (Famerp), Sao Jose do Rio Preto, SP (Brazil); Valente, Rodolfo Silva [Hospital Universitario de Brasilia (HUB), Brasilia, DF (Brazil)

    2012-05-15

    Renal lymphangiectasia is a rare condition characterized by parapyelic and perirenal fluid collections, which may progress from asymptomatic condition to chronic renal failure. The present report describes a case of incidental computed tomography finding of bilateral lymphangiectasia in an asymptomatic patient, as well as the main imaging findings with a comprehensive literature review. (author)

  14. A comparative study for image quality and radiation dose of a cone beam computed tomography scanner and a multislice computed tomography scanner for paranasal sinus imaging

    Energy Technology Data Exchange (ETDEWEB)

    Cock, Jens de; Canning, John [University Hospitals Leuven, Department of Radiology, Leuven (Belgium); Zanca, Federica; Hermans, Robert [University Hospitals Leuven, Department of Radiology, Leuven (Belgium); KU Leuven, Imaging and Pathology Department, Leuven (Belgium); Pauwels, Ruben [KU Leuven, Imaging and Pathology Department, Leuven (Belgium)

    2015-07-15

    To evaluate image quality and radiation dose of a state of the art cone beam computed tomography (CBCT) system and a multislice computed tomography (MSCT) system in patients with sinonasal poliposis. In this retrospective study two radiologists evaluated 57 patients with sinonasal poliposis who underwent a CBCT or MSCT sinus examination, along with a control group of 90 patients with normal radiological findings. Tissue doses were measured using a phantom model with thermoluminescent dosimeters (TLD). Overall image quality in CBCT was scored significantly higher than in MSCT in patients with normal radiologic findings (p-value: 0.00001). In patients with sinonasal poliposis, MSCT scored significantly higher than CBCT (p-value: 0.00001). The average effective dose for MSCT was 42 % higher compared to CBCT (108 μSv vs 63 μSv). CBCT and MSCT are both suited for the evaluation of sinonasal poliposis. In patients with sinonasal poliposis, clinically important structures of the paranasal sinuses can be better delineated with MSCT, whereas in patients without sinonasal poliposis, CBCT turns out to define the important structures of the sinonasal region better. However, given the lower radiation dose, CBCT can be considered for the evaluation of the sinonasal structures in patients with sinonasal poliposis. (orig.)

  15. The Value of Multislice Spiral Computed Tomography in Demonstrating the Relationship between Bronchial and Peripheral Lung Cancer

    Institute of Scientific and Technical Information of China (English)

    Jinwei Qiang; Kangrong Zhou; Yaping Jiang; Xuanguang Ye; Qun Wang; Songtao Xu; Lijie Tan

    2005-01-01

    OBJECITVE To investigate the value of multislice spiral computed tomography (MSCT) in demonstrating the relationship between bronchial and peripheral lung cancer.METHODS MSCT was used to conduct volumetric targeted scans of 0.5 mm collimation for 53 cases of peripheral lung cancer and to demonstrate the relationship between bronchial and peripheral lung cancer by multiplanar reconstrUctions(MPR) images, curved multiplanar reformations(CMPR) and surface shaded display(SSD). The results were compared with macroscopic and microscopic specimens.RESULTS 1) All the bronchi at the 3rd to 7th order were displayed clearly and completely with this CT protocol. The tumors that were related to the bronchus included 29 (96.7%) adenocarcinomas and 13 (76.5%) squamous-cell carcinomas. Statistical analysis showed that there was no significant difference between the two groups (x2 =2.8, P >0.05). 2) The tumorbronchus relationship was divided into four subtypes, i.e. type Ⅰ: the bronchus was obstructed by a tumor, type Ⅱ: the bronchus was obstructed when penetrated by a tumor with tapered narrowing; type Ⅲ: the bronchial lumen shown within the tumor was unobstructed and intact, type Ⅳ: the bronchus ran at the periphery of a tumor, with an intact or narrowed lumen.3) Type Ⅰ occurred in 58.5% (31 cases), in which squamous-cell carcinoma was slightly more common than adenocarcinoma. Both type Ⅱ and type Ⅲ were seen in 15.1%(eight cases of each), of which all were adenocarcinomas. The incidence rate of type Ⅳ was 28.3% (15 cases), of which adenocarcinoma was slightly more frequent than squamous-cell carcinoma. 4)Squamous-cell carcinoma was more common than adenocarcinoma in the tumors in the fourth-order bronchus, whereas adenocarcinoma was more common than squamous-cell carcinoma in tumors with a relationship to the sixth-order bronchus.CONCLUSION MSCT with volumetric targeted scans of ultra-thin sections were conducted followed by MPR,CMPR and SSD reconstruction

  16. Values of multi-slice spiral computed tomography on predicting hypovolemic shock in patients with severe multiple trauma

    Directory of Open Access Journals (Sweden)

    Yang LI

    2013-01-01

    Full Text Available Objective  To investigate the value of multi-slice spiral computed tomography (MSCT on predicting hypovolemic shock in patients with severe multiple trauma. Methods  The clinical and MSCT data of 63 patients with severe multiple trauma admitted to the Trauma Center from Jan. 2008 to Dec. 2011 were retrospectively reviewed. According to the occurrence of hypovolemic shock in 24 hours after CT scan, the patients were divided into shock group (n=34 and stable group (n=29. Blood pressure, heart rate, shock index and injury severity score (ISS on admission were collected and analyzed. Transverse (T and anteroposterior (AP diameter of inferior vena cava (IVC, diameter of abdominal aorta, CT values of enhanced CT of abdominal organs both in early and late phase were measured. The differences of aforementioned parameters between the two groups were compared by Student's ttest. The values of above indexes showing significant difference between the two groups on predicting hypovolemic shock were analyzed by using receiver operating characteristic (ROC curve and logistic regression analysis. Results  The shock index, ISS and collapsibility index (T/AP of IVC in 4 abdominal levels were significantly greater in shock group than in stable group (P<0.05. In early phase of enhanced CT, the mean CT value of spleen was significantly lower in shock group (93±16HU than in stable group (112±24HU, P<0.01, while the mean CT value of adrenal gland was higher in shock group (153±35HU than in stable group (131±24HU, P<0.01. In delayed phase, the mean CT value of renal medulla was significantly lower in shock group (193±57HU than in stable group (228±53HU, P<0.05. The diagnostic cutoff value of ROC curve of shock index, ISS, collapsibility index (T/AP of IVC, CT value of spleen and adrenal gland in early phase, CT value of renal medulla in delayed phase were 1.19, 19.5, 3.02, 115HU, 150HU and 184HU, respectively. Logistic regression analysis showed that ISS, T

  17. Is the corticomedullary index valid to distinguish human from nonhuman bones: a multislice computed tomography study.

    Science.gov (United States)

    Rérolle, Camille; Saint-Martin, Pauline; Dedouit, Fabrice; Rousseau, Hervé; Telmon, Norbert

    2013-09-10

    The first step in the identification process of bone remains is to determine whether they are of human or nonhuman origin. This issue may arise when only a fragment of bone is available, as the species of origin is usually easily determined on a complete bone. The present study aims to assess the validity of a morphometric method used by French forensic anthropologists to determine the species of origin: the corticomedullary index (CMI), defined by the ratio of the diameter of the medullary cavity to the total diameter of the bone. We studied the constancy of the CMI from measurements made on computed tomography images (CT scans) of different human bones, and compared our measurements with reference values selected in the literature. The measurements obtained on CT scans at three different sites of 30 human femurs, 24 tibias, and 24 fibulas were compared between themselves and with the CMI reference values for humans, pigs, dogs and sheep. Our results differed significantly from these reference values, with three exceptions: the proximal quarter of the femur and mid-fibular measurements for the human CMI, and the proximal quarter of the tibia for the sheep CMI. Mid-tibial, mid-femoral, and mid-fibular measurements also differed significantly between themselves. Only 22.6% of CT scans of human bones were correctly identified as human. We concluded that the CMI is not an effective method for determining the human origin of bone remains.

  18. Bone density: comparative evaluation of Hounsfield units in multislice and cone-beam computed tomography

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    Isabela Maria de Carvalho Crusoé Silva

    2012-12-01

    Full Text Available The aim of this study was to evaluate the validity of the bone density value of potential implant sites in HU obtained by a specific cone-beam computed tomography (CBCT device. In this study, the HU values obtained using a MSCT scanner were used as the gold standard. Twenty mandibles (40 potential implant sites were scanned using an MSCT scanner (Somatom Sensation 40 and a CBCT scanner (i-CAT. The MSCT images were evaluated using the Syngo CT Workplace software and the CBCT images, using the XoranCat software. The images were evaluated twice by three oral radiologists, at 60 day intervals. The trabecular bone density of the same area was evaluated on both images. Intraclass coefficients (ICC were calculated to examine the agreement between the examiners and between the two periods of evaluation. The bone density and area of the ROI were compared by the Student t test and Bland-Altman analysis. ICCs were excellent. The mean HU value obtained using CBCT (418.06 was higher than that obtained using MSCT (313.13, with a statistically significant difference (p < 0.0001. In addition, Bland-Altman analysis showed that the HU measures were not equivalent. In conclusion, the bone density in HU with CBCT images obtained using the device studied proved unreliable, since it was higher than that obtained using MSCT.

  19. Multislice computed tomography perfusion imaging for visualization of acute pulmonary embolism: animal experience

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    Wildberger, Joachim Ernst; Spuentrup, Elmar; Mahnken, Andreas H.; Guenther, Rolf W. [University Hospital, RWTH Aachen, Department of Diagnostic Radiology, Aachen (Germany); Klotz, Ernst; Ditt, Hendrik [Computed Tomography, Siemens Medical Solutions, Forchheim (Germany)

    2005-07-01

    The purpose of our animal study was to evaluate a new computed tomography (CT) subtraction technique for visualization of perfusion defects within the lung parenchyma in subsegmental pulmonary embolism (PE). Seven healthy pigs were entered into a prospective trial. Acute PE was artificially induced by fresh clot material prior to the CT scans. Within a single breath-hold, whole thorax CT scans were performed with a 16-slice multidetector-row CT scanner (SOMATOM Sensation 16; Siemens, Forchheim, Germany) before and after intravenous application of 80 ml of contrast medium with a flow rate of 4 ml/s, followed by a saline chaser. The scan parameters were 120 kV and 100 mAs{sub eff}, using a thin collimation of 16 x 0.75 mm and a table speed/rotation of 15-18 mm (pitch, 1.25-1.5; rotation time, 0.5 s). Axial source images were reconstructed with an effective slice thickness of 1 mm (overlap, 30%). A new automatic subtraction technique was used. After 3D segmentation of the lungs in the plain and contrast-enhanced series, threshold-based extraction of major airways and vascular structures in the contrast images was performed. This segmentation was repeated in the plain CT images segmenting the same number of vessels and airways as in the contrast images. Both scans were registered onto each other using nonrigid registration. After registration both image sets were filtered in a nonlinear fashion excluding segmented airways and vessels. After subtracting the plain CT data from the contrast data the resulting enhancement images were color-encoded and overlaid onto the contrast-enhanced CT angiography (CTA) images. This color-encoded combined display of parenchymal enhancement of the lungs was evaluated interactively on a workstation (Leonardo, Siemens) in axial, coronal and sagittal plane orientations. Axial contrast-enhanced CTA images were rated first, followed by an analysis of the combination images. Finally, CTA images were reread focusing on areas with perfusion

  20. Comparison between helical computed tomography angiography and intraoperative findings

    Directory of Open Access Journals (Sweden)

    Abijit Shetty

    2014-01-01

    Conclusions: Helical CT is important in delineating the arterial, venous, and ureteral anatomy and can show the important incidental findings. Left renal donors and males have more variations in their renal anatomy. Technically challenging laparoscopic nephrectomy on the multiple-vessel-side donor is possible with the aid of helical CT. The importance of the CT in evaluating donor renal anatomy for a technically challenging laparoscopic donor nephrectomy is commendable.

  1. Evaluation of the characteristics of hepatic focal nodular hyperplasia: correlation between dynamic contrast-enhanced multislice computed tomography and pathological findings

    Directory of Open Access Journals (Sweden)

    Zhang HT

    2016-08-01

    Full Text Available Hai-Tao Zhang,1,* Xin-Yi Gao,2,* Qin-Sha Xu,1 Yu-Tang Chen,3 Yu-Piao Song,1 Zhen-Wei Yao2 1Department of Radiology, Jiangwan Hospital, 2Department of Radiology, Affiliated Huashan Hospital of Fudan University, Shanghai, 3Department of Radiology, Zhejiang Province Tumor Hospital, Hangzhou, People’s Republic of China *These authors contributed equally to this work Objective: To evaluate the characteristics of enhancement of focal nodular hyperplasia (FNH of the liver by analyzing the dynamic contrast-enhanced multislice computed tomography (MSCT features and correlating them with pathological findings.Patients and methods: Nine males and 16 females with pathologically confirmed FNH and complete preoperative contrast-enhanced MSCT data were recruited for this study. The imaging features of FNH on the pre- and postcontrast MSCT were analyzed by two experienced radiologists by consensus.Results: Pathology showed central scars and abnormal blood vessels in 17 and 21 of 25 lesions, respectively, while MSCT with multiphase enhancement showed central scars in eight of the 17 lesions (47.1% and abnormal arteries or draining veins in 13 of the 21 lesions (61.9%. Furthermore, abnormal draining veins in five lesions were found to be diagnostic, which is another important finding.Conclusion: Multiphase scanning can provide the panorama of FNH lesions and reveal their enhancement patterns and pathological characteristics. Abnormal blood vessels within or around the lesion are demonstrated more often than central scar, and both should be observed for FNH diagnosis. Keywords: liver, focal nodular hyperplasia, multislice computed tomography, pathological findings, contrast enhancement, abnormal vein

  2. Computational Investigation of Experimental Interaction Impedance Obtained by Perturbation for Helical Traveling Wave Tube Structures

    Science.gov (United States)

    Kory, Carol L.; Dayton, James A., Jr.

    1998-01-01

    Conventional methods used to measure the cold- test interaction impedance of helical slow-wave structures involve perturbing a helical circuit with a cylindrical dielectric rod placed on the central axis of the circuit It has been shown that the difference in resonant frequency or axial phase shift between the perturbed and unperturbed circuits can be related to the interaction impedance. However, because of the complex configuration of the helical circuit, deriving this relationship involves several approximations. With the advent of accurate three-dimensional (3-D) helical circuit models, these standard approximations can be fully Investigated. This paper addresses the most prominent approximations made in the analysis for measured interaction impedance by Lagerstrom and investigates their accuracy using the 3-D simulation code MAFIA. It is shown that a more accurate value of interaction impedance can be obtained by using 3-D computational methods rather than performing costly and time consuming experimental cold-test measurements.

  3. Computational Investigation of Experimental Interaction Impedance Obtained by Perturbation for Helical Traveling-Wave Tube Structures

    Science.gov (United States)

    Kory, Carol L.; Dayton, J. A., Jr.

    1998-01-01

    Conventional methods used to measure the cold-test interaction impedance of helical slow-wave structures involve perturbing a helical circuit with a cylindrical dielectric rod placed on the central axis of the circuit. It has been shown that the difference in resonant frequency or axial phase shift between the perturbed and unperturbed circuits can be related to the interaction impedance. However, because of the complex configuration of the helical circuit, deriving this relationship involves several approximations. With the advent of accurate three-dimensional (3-D) helical circuit models, these standard approximations can be fully investigated. This paper addresses the most prominent approximations made in the analysis for measured interaction impedance by Lagerstrom and investigates their accuracy using the 3-D simulation code MAFIA. It is shown that a more accurate value of interaction impedance can be obtained by using 3-D computational methods rather than performing costly and time consuming experimental cold-test measurements.

  4. Comparison of lung scintigraphy with multi-slice spiral computed tomography in the diagnosis of pulmonary embolism.

    Science.gov (United States)

    Wang, Feng; Fang, Wei; Lv, Bin; Lu, Jin-Guo; Xiong, Chang-Ming; Ni, Xin-Hai; He, Zuo-Xiang

    2009-07-01

    To compare the diagnostic efficacy of lung perfusion scans combined with ventilation (V/Q) scans and/or chest radiography (CR) with contrast-enhanced multislice spiral CT pulmonary angiography (CTPA) in diagnosing pulmonary embolism (PE). Eighty-two consecutive patients with suspected PE underwent CTPA, lung perfusion scan, and CR. Of them, 28 patients underwent V/Q scans. The final diagnosis was made using a composite reference test. The overall sensitivity and specificity were 89.2% and 92.1% for V/Q scan or perfusion scan combined with CR, and 97.3% and 97.4% for CTPA. For the 28 patients with V/Q scan, the sensitivity and specificity were 91.7% and 92.9% for V/Q scan, and 91.7% and 100.0% for CTPA. The segmental agreement rate between perfusion scan and CTPA was 69.5% (kappa = 0.30, P < 0.05). The perfusion scan revealed significantly more subsegmental abnormalities than CTPA (59 vs. 10, chi2 test, P < 0.05). V/Q scan, perfusion scan combined with CR and CTPA all show high efficacy in diagnosing PE. V/Q scan or perfusion scan combined with CR is as accurate as CTPA.

  5. Comprehensive cardiac assessment with multislice computed tomography: evaluation of left ventricular function and perfusion in addition to coronary anatomy in patients with previous myocardial infarction

    Science.gov (United States)

    Henneman, M M; Schuijf, J D; Jukema, J W; Lamb, H J; de Roos, A; Dibbets, P; Stokkel, M P; van der Wall, E E; Bax, J J

    2006-01-01

    Objective To evaluate a comprehensive multislice computed tomography (MSCT) protocol in patients with previous infarction, including assessment of coronary artery stenoses, left ventricular (LV) function and perfusion. Patients and methods 16‐slice MSCT was performed in 21 patients with previous infarction; from the MSCT data, coronary artery stenoses, (regional and global) LV function and perfusion were assessed. Invasive coronary angiography and gated single‐photon emission computed tomography (SPECT) served as the reference standards for coronary artery stenoses and LV function/perfusion, respectively. Results 236 of 241 (98%) coronary artery segments were interpretable on MSCT. The sensitivity and specificity for detection of stenoses were 91% and 97%. Pearson's correlation showed excellent agreement for assessment of LV ejection fraction between MSCT and SPECT (49 (13)% v 53 (12)%, respectively, r  =  0.85). Agreement for assessment of regional wall motion was excellent (92%, κ  =  0.77). In 68 of 73 (93%) segments, MSCT correctly identified a perfusion defect as compared with SPECT, whereas the absence of perfusion defects was correctly detected in 277 of 284 (98%) segments. Conclusions MSCT permits accurate, non‐invasive assessment of coronary artery stenoses, LV function and perfusion in patients with previous infarction. All parameters can be assessed from a single dataset. PMID:16740917

  6. Trabecular bone structure parameters from 3D image processing of clinical multi-slice and cone-beam computed tomography data

    Energy Technology Data Exchange (ETDEWEB)

    Klintstroem, Eva; Smedby, Oerjan [Linkoeping University, Center for Medical Image Science and Visualization (CMIV), Linkoeping (Sweden); UHL County Council of Oestergoetland, Department of Radiology, Linkoeping (Sweden); Linkoeping University, Department of Medical and Health Sciences (IMH)/Radiology, Linkoeping (Sweden); Moreno, Rodrigo [Linkoeping University, Center for Medical Image Science and Visualization (CMIV), Linkoeping (Sweden); Linkoeping University, Department of Medical and Health Sciences (IMH)/Radiology, Linkoeping (Sweden); Brismar, Torkel B. [KUS Huddinge, Department of Clinical Science, Intervention and Technology at Karolinska Institutet and Department of Radiology, Stockholm (Sweden)

    2014-02-15

    Bone strength depends on both mineral content and bone structure. The aim of this in vitro study was to develop a method of quantitatively assessing trabecular bone structure by applying three-dimensional image processing to data acquired with multi-slice and cone-beam computed tomography using micro-computed tomography as a reference. Fifteen bone samples from the radius were examined. After segmentation, quantitative measures of bone volume, trabecular thickness, trabecular separation, trabecular number, trabecular nodes, and trabecular termini were obtained. The clinical machines overestimated bone volume and trabecular thickness and underestimated trabecular nodes and number, but cone-beam CT to a lesser extent. Parameters obtained from cone beam CT were strongly correlated with μCT, with correlation coefficients between 0.93 and 0.98 for all parameters except trabecular termini. The high correlation between cone-beam CT and micro-CT suggest the possibility of quantifying and monitoring changes of trabecular bone microarchitecture in vivo using cone beam CT. (orig.)

  7. Lung scintigraphy and helical computed tomography for the diagnosis of pulmonary embolism : A meta-analysis

    NARCIS (Netherlands)

    van Beek, EJR; Brouwers, EMJ; Song, B; Bongaerts, AHH; Oudkerk, M

    To assess the diagnostic value of lung scintigraphy and helical computed tomography (hCT) in patients with suspected pulmonary embolism (PE), all English-language articles that described lung scintigraphy and hCT in patients with suspected PE were retrieved. Articles were assessed for strength of

  8. Effective dose to patient measurements in flat-detector and multislice computed tomography: a comparison of applications in neuroradiology.

    Science.gov (United States)

    Struffert, Tobias; Hauer, Michael; Banckwitz, Rosemarie; Köhler, Christoph; Royalty, Kevin; Doerfler, Arnd

    2014-06-01

    Flat-detector CT (FD-CT) is used for a variety of applications. Additionally, 3D rotational angiography (3D DSA) is used to supplement digital subtraction angiography (DSA) studies. The aim was to measure and compare the dose of (1) standard DSA and 3D DSA and (2) analogous FD-CT and multislice CT (MSCT) protocols. Using an anthropomorphic phantom, the effective dose to patients (according to ICRP 103) was measured on an MSCT and a flat-detector angiographic system using standard protocols as recommended by the manufacturer. (1) Evaluation of DSA and 3D DSA angiography protocols: ap.-lat. Standard/low-dose series 1/0.8 mSv, enlarged oblique projection 0.3 mSv, 3D DSA 0.9 mSv (limited coverage length 0.3 mSv). (2) Comparison of FD-CT and MSCT: brain parenchyma imaging 2.9 /1.4 mSv, perfusion imaging 2.3/4.2 mSv, temporal bone 0.2 /0.2 mSv, angiography 2.9/3.3 mSv, limited to the head using collimation 0.5/0.5 mSv. The effective dose for an FD-CT application depends on the application used. Using collimation for FD-CT applications, the dose may be reduced considerably. Due to the low dose of 3D DSA, we recommend using this technique to reduce the number of DSA series needed to identify working projections. Effective dose of FD-CT in comparison to MSCT is in comparable range. Collimation decreases the dose of FD-CT effectively. Effective dose of 3-D angiography is identical to 2-D DSA. Different FD-CT programs have different dose.

  9. Effective dose to patient measurements in flat-detector and multislice computed tomography: a comparison of applications in neuroradiology

    Energy Technology Data Exchange (ETDEWEB)

    Struffert, Tobias; Hauer, Michael; Doerfler, Arnd [University of Erlangen-Nuremberg, Department of Neuroradiology, Erlangen (Germany); Banckwitz, Rosemarie; Koehler, Christoph [Siemens AG, Healthcare Sector, Forchheim (Germany); Royalty, Kevin [Siemens Medical Solutions, USA, Inc, Hoffman Estates, IL (United States); University of Wisconsin, Department of Biomedical Engineering and School of Medicine and Public Health, Madison, WI (United States)

    2014-06-15

    Flat-detector CT (FD-CT) is used for a variety of applications. Additionally, 3D rotational angiography (3D DSA) is used to supplement digital subtraction angiography (DSA) studies. The aim was to measure and compare the dose of (1) standard DSA and 3D DSA and (2) analogous FD-CT and multislice CT (MSCT) protocols. Using an anthropomorphic phantom, the effective dose to patients (according to ICRP 103) was measured on an MSCT and a flat-detector angiographic system using standard protocols as recommended by the manufacturer. (1) Evaluation of DSA and 3D DSA angiography protocols: ap.-lat. Standard/low-dose series 1/0.8 mSv, enlarged oblique projection 0.3 mSv, 3D DSA 0.9 mSv (limited coverage length 0.3 mSv). (2) Comparison of FD-CT and MSCT: brain parenchyma imaging 2.9 /1.4 mSv, perfusion imaging 2.3/4.2 mSv, temporal bone 0.2 /0.2 mSv, angiography 2.9/3.3 mSv, limited to the head using collimation 0.5/0.5 mSv. The effective dose for an FD-CT application depends on the application used. Using collimation for FD-CT applications, the dose may be reduced considerably. Due to the low dose of 3D DSA, we recommend using this technique to reduce the number of DSA series needed to identify working projections. (orig.)

  10. [Proper technics and the reduction of radiation in helical computed tomography].

    Science.gov (United States)

    Cordoliani, Y S; Hazebroucq, V; Sarrazin, J L; Lévêque, C; Marque, B; Goasdoué, P

    1999-02-01

    Helical computed tomography is the main source of ionizing radiation delivery in diagnostic radiology. For each series, average radiation dose is between 20 and 30 mGy. This dose can potentially be reduced by decreasing intensity or voltage and by increasing pitch. Helical acquisition allows reformating of images with smaller increment or different obliquity, and avoids additional irradiation. Hardware and software devices designed for dose reduction must be systematically used. Users of CT systems should be aware of radiation dose delivered with CT and must carefully assess the need of each additional acquisition. Obsolete habits, as gantry tilting for lumbar CT, which increases patient exposure, must be given up. Rational use of helical CT decreases radiation exposure and gains time, whereas thoughtless use increases radiation exposure without real benefit.

  11. Quantitative multi-slice computed tomography assessment of the mitral valvular complex for transcatheter mitral valve interventions part 1: systematic measurement methodology and inter-observer variability.

    Science.gov (United States)

    Thériault-Lauzier, Pascal; Mylotte, Darren; Dorfmeister, Magdalena; Spaziano, Marco; Andalib, Ali; Mamane, Samuel; Chetrit, Michael; Blanke, Philipp; Cecere, Renzo; Buithieu, Jean; Martucci, Giuseppe; Tchetche, Didier; Modine, Thomas; van Mieghem, Nicolas; Lange, Rüdiger; Windecker, Stephan; Bilodeau, Luc; Leipsic, Jonathon; Piazza, Nicolo

    2016-10-10

    Transcatheter mitral valve replacement (TMVR) is an emerging technology with the potential to treat patients with severe mitral regurgitation at excessive risk for surgical mitral valve surgery. Multimodality imaging of the mitral valvular complex and surrounding structures will be an important component for patient selection for TMVR. Our aim was to describe and evaluate a systematic multi-slice computed tomography (MSCT) image analysis methodology that provides measurements relevant for transcatheter mitral valve replacement. A systematic step-by-step measurement methodology is described for structures of the mitral valvular complex including: the mitral valve annulus, left ventricle, left atrium, papillary muscles and left ventricular outflow tract. To evaluate reproducibility, two observers applied this methodology to a retrospective series of 49 cardiac MSCT scans in patients with heart failure and significant mitral regurgitation. For each of 25 geometrical metrics, we evaluated inter-observer difference and intra-class correlation. The inter-observer difference was below 10% and the intra-class correlation was above 0.81 for measurements of critical importance in the sizing of TMVR devices: the mitral valve annulus diameters, area, perimeter, the inter-trigone distance, and the aorto-mitral angle. MSCT can provide measurements that are important for patient selection and sizing of TMVR devices. These measurements have excellent inter-observer reproducibility in patients with functional mitral regurgitation.

  12. Sixteen-row multislice computed tomography in the assessment of pulmonary veins prior to ablative treatment: validation vs conventional pulmonary venography and study of reproducibility

    Energy Technology Data Exchange (ETDEWEB)

    Maksimovic, R.; Cademartiri, F.; Pattynama, P.M.T. [Erasmus Medical Center, Rotterdam (Netherlands). Dept. of Radiology; Scholten, M; Jordaens, L.J. [Erasmus Medical Center, Rotterdam (Netherlands). Dept. of Cardiology

    2004-03-01

    The aim of this study was to validate multislice computed tomography (MSCT) venography measurements of pulmonary vein (PV) diameters vs conventional pulmonary venography (CPV), and to assess the reproducibility of MSCT data. The study included 21 consecutive patients with atrial fibrillation who were planned for cryothermal ablation of PVs. One day before ablation, all patients underwent CPV and contrast-enhanced non-gated MSCT venography. The MSCT was repeated 3 months after ablation. The CPV images of the treated PVs (n=40) were analyzed and compared with the results of MSCT measurements. Reproducibility of MSCT venography-based data was assessed by interobserver (n=84 PVs) and interexamination (n=44 PVs) variability. Pre-treatment PV diameters on MSCT and CPV showed good correlation (r=0.87, p<0.01; 18.9{+-}2.3 mm, 188.5{+-}2.4 mm, respectively). Interobserver agreement and interexamination reproducibility were good (r=0.91, r=0.82, respectively, p<0.01), with narrow limits of agreement (Bland and Altman method). The MSCT venography allows accurate and reproducible assessment of PVs. It can be used both in non-invasive planning of treatment for ablative therapy and in the follow-up of patients.

  13. Impact of sirolimus-eluting stent fractures without early cardiac events on long-term clinical outcomes: A multislice computed tomography study

    Energy Technology Data Exchange (ETDEWEB)

    Ito, Tsuyoshi [Toyohashi Heart Center, Oyama-cho, Toyohashi (Japan); Nagoya City University Graduate School of Medical Sciences, Department of Cardio-Renal Medicine and Hypertension, Nagoya (Japan); Kimura, Masashi; Ehara, Mariko; Terashima, Mitsuyasu; Nasu, Kenya; Kinoshita, Yoshihisa; Habara, Maoto; Tsuchikane, Etsuo; Suzuki, Takahiko [Toyohashi Heart Center, Oyama-cho, Toyohashi (Japan)

    2014-05-15

    This study sought to evaluate the impact of sirolimus-eluting stent (SES) fractures on long-term clinical outcomes using multislice computed tomography (MSCT). In this study, 528 patients undergoing 6- to 18-month follow-up 64-slice MSCT after SES implantation without early clinical events were followed clinically (the median follow-up interval was 4.6 years). A CT-detected stent fracture was defined as a complete gap with Hounsfield units (HU) <300 at the site of separation. The major adverse cardiac events (MACEs), including cardiac death, stent thrombosis, and target lesion revascularisation, were compared according to the presence of stent fracture. Stent fractures were observed in 39 patients (7.4 %). MACEs were more common in patients with CT-detected stent fractures than in those without (46 % vs. 7 %, p < 0.01). Univariate Cox regression analysis indicated a significant relationship between MACE and stent fracture [hazard ratio (HR) 7.65; p < 0.01], age (HR 1.03; p = 0.04), stent length (HR 1.03; p < 0.01), diabetes mellitus (HR 1.77; p = 0.04), and chronic total occlusion (HR 2.54; p = 0.01). In the multivariate model, stent fracture (HR 5.36; p < 0.01) and age (HR 1.03; p = 0.04) remained significant predictors of MACE. An SES fracture detected by MSCT without early clinical events was associated with long-term clinical adverse events. (orig.)

  14. A comparative evaluation of Cone Beam Computed Tomography (CBCT) and Multi-Slice CT (MSCT). Part II: On 3D model accuracy

    Energy Technology Data Exchange (ETDEWEB)

    Liang Xin, E-mail: Xin.Liang@med.kuleuven.b [Oral Imaging Centre, School of Dentistry, Oral Pathology and Maxillofacial Surgery, Faculty of Medicine, Catholic University of Leuven (Belgium); College of Stomatology, Dalian Medical University (China); Lambrichts, Ivo, E-mail: Ivo.Lambrichts@uhasselt.b [Department of Basic Medical Sciences, Histology and Electron Microscopy, Faculty of Medicine, University of Hasselt, Diepenbeek (Belgium); Sun Yi, E-mail: Sunyihello@hotmail.co [Oral Imaging Centre, School of Dentistry, Oral Pathology and Maxillofacial Surgery, Faculty of Medicine, Catholic University of Leuven (Belgium); Denis, Kathleen, E-mail: kathleen.denis@groept.b [Department of Industrial Sciences and Techology-Engineering (IWT), XIOS Hogeschool Limburg, Hasselt (Belgium); Hassan, Bassam, E-mail: b.hassan@acta.n [Department of Oral Radiology, Academic Centre for Dentistry Amsterdam (ACTA), Amsterdam (Netherlands); Li Limin, E-mail: Limin.Li@uz.kuleuven.b [Department of Paediatric Dentistry and Special Dental Care, School of Dentistry, Oral Pathology and Maxillofacial Surgery, Faculty of Medicine, Catholic University of Leuven (Belgium); Pauwels, Ruben, E-mail: Ruben.Pauwels@med.kuleuven.b [Oral Imaging Centre, School of Dentistry, Oral Pathology and Maxillofacial Surgery, Faculty of Medicine, Catholic University of Leuven (Belgium); Jacobs, Reinhilde, E-mail: Reinhilde.Jacobs@uz.kuleuven.b [Oral Imaging Centre, School of Dentistry, Oral Pathology and Maxillofacial Surgery, Faculty of Medicine, Catholic University of Leuven (Belgium)

    2010-08-15

    Aim: The study aim was to compare the geometric accuracy of three-dimensional (3D) surface model reconstructions between five Cone Beam Computed Tomography (CBCT) scanners and one Multi-Slice CT (MSCT) system. Materials and methods: A dry human mandible was scanned with five CBCT systems (NewTom 3G, Accuitomo 3D, i-CAT, Galileos, Scanora 3D) and one MSCT scanner (Somatom Sensation 16). A 3D surface bone model was created from the six systems. The reference (gold standard) 3D model was obtained with a high resolution laser surface scanner. The 3D models from the five systems were compared with the gold standard using a point-based rigid registration algorithm. Results: The mean deviation from the gold standard for MSCT was 0.137 mm and for CBCT were 0.282, 0.225, 0.165, 0.386 and 0.206 mm for the i-CAT, Accuitomo, NewTom, Scanora and Galileos, respectively. Conclusion: The results show that the accuracy of CBCT 3D surface model reconstructions is somewhat lower but acceptable comparing to MSCT from the gold standard.

  15. Imaging bowel obstruction: A comparison between fast magnetic resonance imaging and helical computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Beall, D.P.; Fortman, B.J.; Lawler, B.C.; Regan, F

    2002-08-01

    AIM: To compare the accuracy of fast magnetic resonance (MR) imaging using the half-Fourier single shot turbo spin echo (HASTE) sequence with helical computed tomography (CT) in diagnosing bowel obstruction. MATERIALS AND METHODS: Prospective evaluation of 44 patients with clinical evidence of bowel obstruction was conducted using various investigations including HASTE MR and helical CT. MR was performed with a Siemens 1.5 Tesla MR Imaging System and CT was performed with one of two Siemens ARHP CT systems using helical technique. MR acquisition allowed data to be gathered in 6-10 minutes and no contrast media were administered. CT imaging consisted of consecutive helical CT through the abdomen and pelvis with oral and intravenous contrast medium used when indicated. Bowel dilation along with the presence and level of obstruction were determined. RESULTS: Twenty-eight patients had bowel obstruction confirmed at laparotomy or by radiographic assessment. Of these, 25 had small bowel obstruction and three had colonic obstructions. The obstruction was due to fibrous adhesions in nine patients, metastases or primary carcinoma in seven, Crohn's disease in four, hernias in two, and inflammation or abscess in two. Other causes of obstruction included lymphoma, intussusception and anastomotic stricture. The cause of obstruction was correctly diagnosed by CT in 71%, and by MR in 95% of cases. The sensitivity, specificity and accuracy for HASTE MR imaging was 95%, 100% and 96% respectively as compared to 71%, 71% and 71% for helical CT. CONCLUSION: Fast MR imaging using the HASTE sequence is more accurate than helical CT in diagnosing bowel obstruction. Beall, D.P. et al. (2002)

  16. Genetic association of glutathione peroxidase-1 with coronary artery calcification in type 2 diabetes: a case control study with multi-slice computed tomography

    Directory of Open Access Journals (Sweden)

    Fujimoto Kei

    2007-09-01

    Full Text Available Abstract Background Although oxidative stress by accumulation of reactive oxygen species (ROS in diabetes has become evident, it remains unclear what genes, involved in redox balance, would determine susceptibility for development of atherosclerosis in diabetes. This study evaluated the effect of genetic polymorphism of enzymes producing or responsible for reducing ROS on coronary artery calcification in type 2 diabetes (T2D. Methods An index for coronary-arteriosclerosis, coronary artery calcium score (CACS was evaluated in 91 T2D patients using a multi-slice computed tomography. Patients were genotyped for ROS-scavenging enzymes, Glutathione peroxidase-1 (GPx-1, Catalase, Mn-SOD, Cu/Zn-SOD, as well as SNPs of NADPH oxidase as ROS-promoting elements, genes related to onset of T2D (CAPN10, ADRB3, PPAR gamma, FATP4. Age, blood pressure, BMI, HbA1c, lipid and duration of diabetes were evaluated for a multivariate regression analysis. Results CACS with Pro/Leu genotype of the GPx-1 gene was significantly higher than in those with Pro/Pro (744 ± 1,291 vs. 245 ± 399, respectively, p = 0.006. In addition, genotype frequency of Pro/Leu in those with CACS ≥ 1000 was significantly higher than in those with CACS OR = 3.61, CI = 0.97–13.42; p = 0.045 when tested for deviation from Hardy-Weinberg's equilibrium. Multivariate regression analyses revealed that CACS significantly correlated with GPx-1 genotypes and age. Conclusion The presence of Pro197Leu substitution of the GPx-1 gene may play a crucial role in determining genetic susceptibility to coronary-arteriosclerosis in T2D. The mechanism may be associated with a decreased ability to scavenge ROS with the variant GPx-1.

  17. Noninvasive assessment of coronary artery disease by multislice spiral computed tomography using a new retrospectively ECG-gated image reconstruction technique. Comparison with angiographic results

    Energy Technology Data Exchange (ETDEWEB)

    Sato, Yuichi; Matsumoto, Naoya; Kato, Masahiko [Nihon Univ., Tokyo (Japan). Surugadai Hospital] [and others

    2003-04-01

    The present study was designed to investigate the accuracy of multislice spiral computed tomography (MSCT) in detecting coronary artery disease, compared with coronary angiography (CAG), using a new retrospectively ECG-gated reconstruction method that reduced cardiac motion artifact. The study group comprised 54 consecutive patients undergoing MSCT and CAG. MSCT was performed using a SOMATOM Volume Zoom (4-detector-row, Siemens, Germany) with slice thickness 1.0 mm, pitch 1.5 (table feed: 1.5 mm per rotation) and gantry rotation time 500 ms. Metoprolol (20-60 mg) was administered orally prior to MSCT imaging. ECG-gated image reconstruction was performed with the reconstruction window (250 ms) positioned immediately before atrial contraction in order to reduce the cardiac motion artifact caused by the abrupt diastolic ventricular movement occurring during the rapid filling and atrial contraction periods. Following inspection of the volume rendering images, multiplanar reconstruction images and axial images of the left main coronary artery (LMCA), left anterior descending artery (LAD), left circumflex artery (LCx) and right coronary artery (RCA) were obtained and evaluated for luminal narrowing. The results were compared with those obtained by CAG. Of 216 coronary arteries, 206 (95.4%) were assessable; 10 arteries were excluded from the analysis because of severe calcification (n=4), stents (n=3) or insufficient contrast enhancement (n=3). The sensitivity to detect coronary stenoses {>=}50% was 93.5% and the specificity to define luminal narrowing <50% was 97.2%. The positive predictive value and the negative predictive value were 93.5% and 97.2%, respectively. The sensitivity was still satisfactory (80.6%) even when non-assessable arteries were included in the analysis. The new retrospectively ECG-gated reconstruction method for MSCT has excellent diagnostic accuracy in detecting significant coronary artery stenoses. (author)

  18. Impact of lesion morphology on angiographic and clinical outcomes in patients with chronic total occlusion after recanalization with drug-eluting stents: a multislice computed tomography study

    Energy Technology Data Exchange (ETDEWEB)

    Ito, Tsuyoshi [Toyohashi Heart Center, Toyohashi (Japan); Nagoya City University Graduate School of Medical Sciences, Department of Cardio-Renal Medicine and Hypertension, Nagoya (Japan); Tsuchikane, Etsuo; Nasu, Kenya; Kimura, Masashi; Terashima, Mitsuyasu; Kinoshita, Yoshihisa; Habara, Maoto; Suzuki, Takahiko [Toyohashi Heart Center, Toyohashi (Japan); Suzuki, Yoriyasu; Ehara, Mariko [Nagoya Heart Center, Nagoya (Japan); Ohte, Nobuyuki [Nagoya City University Graduate School of Medical Sciences, Department of Cardio-Renal Medicine and Hypertension, Nagoya (Japan)

    2015-10-15

    The aim of this study was to investigate the multislice computed tomography (MSCT) parameters associated with adverse outcomes after chronic total occlusion percutaneous coronary intervention (CTO-PCI) with drug-eluting stents. A total of 285 patients who underwent MSCT before CTO-PCI were analyzed. Lesion morphology was assessed with MSCT. Angiographic restenosis, reocclusion, and MACE (a composite of cardiac death, myocardial infarction, stent thrombosis, and target lesion revascularization) were analyzed. MACE was observed in 36 patients (13.6 %). Occlusion length was greater (39.5 ± 19.9 mm vs. 22.3 ± 13.7 mm, p < 0.01), minimal vessel area smaller (11.2 ± 5.7 mm{sup 2} vs. 14.5 ± 5.6 mm{sup 2}, p < 0.01), and severe calcification more common (36 % vs. 12 %, p < 0.01) in the MACE group compared to the non-MACE group. We defined occluded length >25.4 mm, minimal vessel area <11.9 mm{sup 2}, which were identified by receiver operating characteristic analysis, and severe calcification as CT-derived risk factors. Angiographic restenosis (60 % vs. 12 % vs. 7 %, p < 0.01), reocclusion (29 % vs. 2 % vs. 2 %, p < 0.01), and MACE (43 % vs. 6 % vs. 3 %, p < 0.01) were more common in patients with 2 or more risk factors than in those with 1 or 0. MSCT characteristics associated with adverse outcomes after CTO-PCI were occlusion length, minimal vessel area, and severe calcification. (orig.)

  19. Development of modern human subadult age and sex estimation standards using multi-slice computed tomography images from medical examiner's offices

    Science.gov (United States)

    Stock, Michala K.; Stull, Kyra E.; Garvin, Heather M.; Klales, Alexandra R.

    2016-10-01

    Forensic anthropologists are routinely asked to estimate a biological profile (i.e., age, sex, ancestry and stature) from a set of unidentified remains. In contrast to the abundance of collections and techniques associated with adult skeletons, there is a paucity of modern, documented subadult skeletal material, which limits the creation and validation of appropriate forensic standards. Many are forced to use antiquated methods derived from small sample sizes, which given documented secular changes in the growth and development of children, are not appropriate for application in the medico-legal setting. Therefore, the aim of this project is to use multi-slice computed tomography (MSCT) data from a large, diverse sample of modern subadults to develop new methods to estimate subadult age and sex for practical forensic applications. The research sample will consist of over 1,500 full-body MSCT scans of modern subadult individuals (aged birth to 20 years) obtained from two U.S. medical examiner's offices. Statistical analysis of epiphyseal union scores, long bone osteometrics, and os coxae landmark data will be used to develop modern subadult age and sex estimation standards. This project will result in a database of information gathered from the MSCT scans, as well as the creation of modern, statistically rigorous standards for skeletal age and sex estimation in subadults. Furthermore, the research and methods developed in this project will be applicable to dry bone specimens, MSCT scans, and radiographic images, thus providing both tools and continued access to data for forensic practitioners in a variety of settings.

  20. Diagnostic Value of Multislice Computed Tomography and Magnetic Resonance Imaging in the Diagnosis of Retroperitoneal Spread of Testicular Cancer: A Literature Review

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, J. (Dept. of Medical Physics, Aarhus Univ. Hospital, Aarhus Sygehus, Aarhus (Denmark)); Jurik, A.G. (Dept. of Radiology, Aarhus Univ. Hospital, Aarhus Sygehus, Aarhus (Denmark))

    2009-11-15

    Testicular cancer is the most frequent malignant disorder in men aged 15-35 years. Generally, diagnosing and follow-up include computer tomography (CT) examinations to detect possible retroperitoneal spread (abdomen and pelvis), resulting in at least eight CT examinations. This patient group is thereby exposed to a non-neglectable radiation dose, increasing the risk of future radiation-induced secondary cancer. This is especially problematic in potentially surgically cured patients with stage 1 testicular cancer. Thus, it can be beneficial to substitute CT with magnetic resonance imaging (MRI), provided there is valid evidence that the diagnostic value of MRI is at least comparable to current multislice CT (MSCT). The purpose of this study was to analyze whether there is evidence to recommend a substitution of MSCT with MRI in the diagnosis of retroperitoneal spread of testicular cancer. A literature search on the diagnostic accuracy, specificity, and sensitivity of MSCT and MRI in the diagnosis of retroperitoneal spread of testicular cancer was performed in the following databases: PubMed, EmBase, and ISI Web of Science. The search was limited to include the period from 2000 to September 2008, and to human and English-language publications. Forty-four publications were obtained for formal review (27 from PubMed, 15 from EmBase, two from ISI Web of Science). None of the publications reviewed encompassed diagnostic specificity and sensitivity of MSCT, and they lacked systematic comparison of MSCT and MRI. Only one study included sensitivity and specificity of MRI compared to single-slice CT. Both methods had a sensitivity and a specificity of approximately 70%. The literature review did not reveal valid data regarding diagnostic accuracy of MRI compared with MSCT for diagnosing retroperitoneal spread of testicular cancer. A prospective blinded comparative study is needed to provide valid evidence

  1. The evaluation of anti-angiogenic treatment effects for implanted rabbit VX2 breast tumors using functional multi-slice spiral computed tomography (f-MSCT)

    Energy Technology Data Exchange (ETDEWEB)

    Lei Zhen, E-mail: leizhen2004@163.com [Department of Anatomy, Chinese Medical University, No. 92, Beiermalu Road, Heping District, Shenyang, 110001 (China) and Department of Radiology, The First Hospital of Liaoning Medical College, No. 2, Wuduan, Renmin Street, Jinzhou, 121001 (China); Ma Heji, E-mail: maheji9831@sina.com [Department of Radiology, The First Hospital of Liaoning Medical College, No. 2, Wuduan, Renmin Street, Jinzhou, 121001 (China); Xu Na, E-mail: xuna821230@sohu.com [Department of Radiology, The First Hospital of Liaoning Medical College, No. 2, Wuduan, Renmin Street, Jinzhou, 121001 (China); Xi Huanjiu, E-mail: xihuanjiu2004@yahoo.cn [Anthropology Institute, Liaoning Medical College, No. 40, Sanduan, Songpo Rd, Jinzhou, 121001 (China)

    2011-05-15

    Objective: Investigate the benefit of functional multi-slice spiral computed tomography (f-MSCT) perfusion imaging in the non-invasive assessment of targeted anti-angiogenesis therapy on an implanted rabbit VX2 breast tumor model. Method: 69 female pure New Zealand white rabbits were randomly assigned to one of the 4 groups and received treatment accordingly: control (saline), Endostar, neoadjuvant chemotherapy (Cyclophosphamide, Epirubicin and 5-Fluorouracil, CEF), combination therapy (Endostar and CEF). After 2 weeks of treatment, f-MSCT perfusion scannings were performed for all rabbits and information about blood flow (BF), blood volume (BV), mean transit time (MTT) and surface permeability (SP) was collected. After perfusion imaging, tumor tissues were sampled for immunohistochemistry and the Western blot test of VEGF protein expression. Results: (1) The VEGF expression level, measured by immunohistochemistry and Western blot, decreased by treatment group (control > Endostar > CEF > combination therapy). The same was true for the mean BF, BV, MTT and PS, which decreased from the control group to the combination therapy group gradually. The mean MTT level increased in reverse order from the control to the combination therapy group. The difference between any 2 groups on these measures was statistically significant (P < 0.05). (2) There was moderate positive correlation between VEGF expression and BE, BV, or PS level (P < 0.05) and a negative correlation between VEGF expression and MTT level for all 4 groups (P < 0.05). Conclusion: Therefore, f-MSCT can be used as a non-invasive approach to evaluate the effect of anti-angiogenic therapy for implanted rabbit VX2 breast tumors.

  2. Apneic oxygenation for elimination of respiratory motion artefact in an intubated patient undergoing helical chest computed tomography angiography.

    Directory of Open Access Journals (Sweden)

    Ioannis Pneumatikos

    2008-10-01

    Full Text Available Respiratory motion artifact in intubated and mechanically ventilated patients often reduces the quality of helical computed tomography pulmonary angiography (CTPA. Apneic oxygenation is a well established intra-operative technique that allows adequate oxygenation for short periods (up to 10 min in sedated and paralyzed patients. We describe the use of the apneic oxygenation for elimination of respiratory motion artefact in an intubated patient undergoing helical chest computed tomography angiography.

  3. Automatic liver segmentation method featuring a novel filter for multiphase multidetector-row helical computed tomography.

    Science.gov (United States)

    Hirose, Tomohiro; Nitta, Norihisa; Tsudagawa, Masaru; Takahashi, Masashi; Murata, Kiyoshi

    2011-01-01

    To introduce an automatic liver segmentation method that includes a novel filter for multiphase multidetector-row helical computed tomography. We acquired 3-phase multidetector-row computed tomographic scans that included unenhanced, arterial, and portal phases. The liver was segmented using our novel adaptive linear prediction filter designed to reduce the difference between filter input and output values in the liver region and to increase these values outside the liver region. The segmentation algorithm produced a mean dice similarity coefficient (DSC) value of 91.4%. The application of our adaptive linear prediction filter was effective in automatically extracting liver regions.

  4. Value of multislice computed tomography angiography of the thorax in preparation for catheter ablation for the treatment of atrial fibrillation: The impact of unexpected cardiac and extracardiac findings on patient care

    Energy Technology Data Exchange (ETDEWEB)

    Wissner, Erik; Wellnitz, Clinton V.; Srivathsan, Komandoor; Scott, Luis R. [Mayo Clinic Arizona - Mayo Clinic Hospital, Cardiovascular Diseases, 5777 East Mayo Boulevard, Phoenix, AZ 85054 (United States); Altemose, Gregory T. [Mayo Clinic Arizona - Mayo Clinic Hospital, Cardiovascular Diseases, 5777 East Mayo Boulevard, Phoenix, AZ 85054 (United States)], E-mail: altemose.gregory@mayo.edu

    2009-11-15

    Objective: In patients referred for catheter ablation for the treatment of atrial fibrillation, multislice computed tomography angiography of the thorax is routinely performed to assess pulmonary vein anatomy. We sought to investigate the incidence of unexpected cardiac and extracardiac findings in this select patient population and to establish how these findings influence subsequent patient care. Methods: Ninety-five patients (mean age 62 {+-} 10 years, 35% female) referred to our institution for ablation therapy for atrial fibrillation between July 2003 and October 2007 underwent multislice computed tomography angiography of the thorax. Radiologists interpreted all images. Need for additional testing, consultation and eventual diagnosis were assessed by electronic record review. Results: A total of 83 (5 cardiac, 78 extracardiac) unexpected findings were observed in 50/95 (53%) of patients. The findings prompted 23 additional tests (5 cardiac, 18 noncardiac) in 15/95 (16%) of patients and 8 subsequent referrals in 7/95 (7%) patients. In 6 patients the findings significantly altered future patient care and resulted in postponement of ablation therapy in 4 patients. In 2 patients, extracardiac findings (pulmonary emboli and adenocarcinoma of the lung) were of potentially life-saving consequence. Conclusions: In patients undergoing multislice computed tomography angiography of the thorax in anticipation of planned catheter ablation therapy for the treatment of atrial fibrillation, unexpected findings are common and of potentially significant value. In comparison, there is a higher prevalence of unexpected extracardiac, rather than cardiac findings. Further investigation of these findings may lead to postponement of ablation therapy, but may also be of potentially lifesaving consequence.

  5. Usefulness of helical computed tomography in diagnosing pulmonary vein stenosis in infants.

    Directory of Open Access Journals (Sweden)

    Ohtsuki,Shinnichi

    2005-06-01

    Full Text Available

    We investigated the usefulness of helical computed tomography(CTin the morphological diagnosis of pulmonary vein stenosis, particularly that in infants and small children. In total, 20 helical CT examinations were performed in 10 post-operative cases of Total Anomalous Pulmonary Venous Drainage(TAPVD, 3 cases of single right ventricle, and 1 case of single left ventricle. In all cases, distinct morphological imaging was possible. Pulmonary vein stenosis could be categorized into three types: (1stenosis from the anastomosis of the common pulmonary vein (CPV-the left atrium (LA to the peripheral pulmonary vein; (2 stenosis only at the anastomosis of CPV-LA; and (3 stenosis due to compression by nearby organs. Coronal views by multiplanar reconstruction (MPR provided morphological information along the up-down direction of the body axis. Morphological diagnosis of pulmonary vein stenosis is important in deciding prognosis and therapeutic regimens, and helical CT was considered useful for such diagnosis in our 14 young patients.

  6. User's guide for a large signal computer model of the helical traveling wave tube

    Science.gov (United States)

    Palmer, Raymond W.

    1992-01-01

    The use is described of a successful large-signal, two-dimensional (axisymmetric), deformable disk computer model of the helical traveling wave tube amplifier, an extensively revised and operationally simplified version. We also discuss program input and output and the auxiliary files necessary for operation. Included is a sample problem and its input data and output results. Interested parties may now obtain from the author the FORTRAN source code, auxiliary files, and sample input data on a standard floppy diskette, the contents of which are described herein.

  7. 多层螺旋CT在急腹症诊断中的应用%Application of Multislice Spiral Computed Tomography in the Diagnosis of Acute Abdomen

    Institute of Scientific and Technical Information of China (English)

    付子文

    2016-01-01

    目的:探讨多层螺旋CT(MSCT)在急腹症诊断中的应用效果。方法分析237例于2012年6月~2014年5月间在本院疑诊急腹症患者的多层螺旋CT结果,与临床诊断结果进行比较,统计多层螺旋CT诊断急腹症的灵敏度、特异度、准确度、阳性预测值和阴性预测值。结果MSCT诊断的灵敏度为86.2%,特异度为67.6%,准确度为83.5%,阳性预测值为94%,阴性预测值为45.1%。结论MSCT诊断急腹症具有较高的灵敏度、准确度以及阳性预测值,能够实现对急腹症的快速成像,可为病因诊断提供有价值的参考信息,值得临床推广。%Objective To discuss the application effect of multi-slice spiral computed tomography (MSCT) in the diagnosis of acute abdomen. Methods 237 cases of patients with suspected acute abdomen were selected as research subjects in the hospital from June 2012 to May 2014. In comparison with clinical diagnosis, statistical analysis was made by results obtained by MSCT diagnosis in categories of acute abdomen sensitivity, specificity, accuracy, positive predictive value and negative predictive value. Results MSCT diagnostic sensitivity was 86.2%;diagnostic specificity was 67.6%and accuracy was 83.5%;positive predictive value was 94%and negative predictive value was 45.1%. Conclusion The use of MSCT in diagnosis of acute abdomen was characterized by high sensitivity, accuracy, and a high positive predictive value, which could realize rapid imaging of the abdomen, and provide valuable reference information for the diagnosis of the causes of acute abdomen. It was worthy of clinical promotion.

  8. Comparison of SAPIEN 3 and SAPIEN XT transcatheter heart valve stent-frame expansion: evaluation using multi-slice computed tomography

    Science.gov (United States)

    Kazuno, Yoshio; Maeno, Yoshio; Kawamori, Hiroyuki; Takahashi, Nobuyuki; Abramowitz, Yigal; Babak, Hariri; Kashif, Mohammad; Chakravarty, Tarun; Nakamura, Mamoo; Cheng, Wen; Friedman, John; Berman, Daniel; Makkar, Raj R.; Jilaihawi, Hasan

    2016-01-01

    Aims Stent-frame morphology of the newer-generation, balloon-expandable transcatheter heart valve (THV), the SAPIEN 3 (S3), after transcatheter aortic valve implantation (TAVI) is unknown. We evaluated the THV stent-frame morphology post TAVI of the S3 using multi-slice computed tomography (MSCT) compared with the prior-generation THV, SAPIEN XT (S-XT). Methods and results A total of 94 consecutive participants of RESOLVE registry (NCT02318342) had MSCT after balloon-expandable TAVI (S3 = 39 and S-XT = 55). The morphology of the THV stent-frame was evaluated for expansion area and eccentricity at the THV-inflow, native annulus, mid-THV and THV-outflow levels. Mean %-expansion area for the S3 and the S-XT was 100.9 ± 5.7 and 96.1 ± 5.5%, respectively (P < 0.001). In the S3 group, the THV-inflow level had the largest value of %-expansion area, which decreased from THV-inflow to mid-THV level (105.2 ± 6.4 to 96.5 ± 5.9%, P < 0.001). However, in the S-XT group, %-expansion area increased from THV-inflow level to mid-THV level (93.2 ± 6.2 to 95.1 ± 6.1%, P = 0.0058). On nominal delivery balloon volume, the S3 in 88.5% of cases had overexpansion at the THV-inflow level. The observed degree of THV oversizing of the S3 was significantly lower than the S-XT (6.3 ± 8.6 vs. 11.8 ± 8.5%, P = 0.0027). Nonetheless, the incidence of post-procedural paravalvular aortic regurgitation (PVR) ≥ mild following the S3 TAVI was also significantly lower than the S-XT TAVI (17.9 vs. 43.6%, P = 0.014). Conclusion The newer-generation, balloon-expandable device, the S3, has a flared inflow morphology, whereas the prior-generation device, the S-XT, has relatively constrained inflow morphology post TAVI. This may contribute to a lesser degree of PVR with the S3. PMID:27002141

  9. Dual-phase contrast-enhancement multislice computed tomography imaging for the assessment of elderly patients with acute myocardial infarction after primary percutaneous coronary intervention

    Institute of Scientific and Technical Information of China (English)

    Shaofeng Guan; Weiyi Fang; Xinkai Qu; Jianding Ye; Yan Shen; Jing Jiao

    2009-01-01

    Background Evaluation of acute myocardial infarction after reperfusion by dual phase contrast-enhancement multislice computed tomography (MSCT) was implicated in porcine model. There have been few attempts to use this diagnostic modality for the early assessment of coronary reperfusion in patients with ST-elevation myocardial infarction (STEMI), especially after primary percutaneous coronary intervention (PCI). In elderly patients with STEMI, the safety issues remain unknown. Methods Dual phase contrast-enhancement MSCT examinations were performed in 11 elderly patients (≥60 years old) with STEMI within one week after primary PCI. The presence, location and enhancement pattern on MSCT were evaluated. MSCT findings were compared with the catheter angiographic results and area under the curve of creatine kinase (CK) release. Serum creatinine level was recorded before and after MSCT scan. Results MSCT scans were successfully performed in all the patients. Early myocardial perfusion defect (early defect, ED) was detected in all of the 11 patients (100%) in the early phase of the contrast bolus (subendocardial ED in 10 patients and transmural in 1 patient). Mean CT attenuation value of ED was significantly different from CT attenuation value of remote myocardium (46±17 HU vs 104 ± 17 HU; P < 0.01). Location of ED area correlated well with infarction related artery territory on catheter angiography in all of the 11 patients (100%). On delayed phase of MSCT scan, different enhancement patterns were observed: isolated subendocardial late enhancement (LE) in 6 patients, subendocardial residual perfusion defect (RD) and subepicardial LE in 1 patient, subendocardial RD in 4 patients. Infarct volume assessed by MSCT correlated well with area under the curve CK release (R=0.72, P < 0.01). Serum creatinine level after MSCT scan showed no difference with that before MSCT scan. Conclusion Dual phase MSCT could be safely implicated in elderly patients with STEMI. Variable

  10. Prevalence of Coronary Artery Intramyocardial Course in a Large Population of Clinical Patients Detected by Multislice Computed Tomography Coronary Angiography

    Energy Technology Data Exchange (ETDEWEB)

    De Rosa, R.; Sacco, M.; Tedeschi, C.; Pepe, R.; Capogrosso, P.; Montemarano, E.; Rotondo, A.; Runza, G.; Midiri, M.; Cademartiri, F. (UO di Radiologia, Ospedale San Gennaro, Napoli (Italy))

    2008-10-15

    Background: Intramyocardial course, an inborn coronary anomaly, is defined as a segment of a major epicardial coronary artery that runs intramurally through the myocardium; in particular, we distinguish myocardial bridging, in which the vessel returns to an epicardial position after the muscle bridge, and intramyocardial course, which is described as a vessel running and ending in the myocardium. Purpose: To evaluate the prevalence of myocardial bridging and intramyocardial course of coronary arteries as defined by multidetector computed tomography (MDCT) angiography. Material and Methods: The study population consisted of 242 consecutive patients (211 men, 31 women; mean age 59+-6 years) with atypical chest pain admitted to our hospital between December 2004 and September 2006. All MDCT examinations were performed using a 16-detector-row scanner (Aquilion 16 CFX; Toshiba Medical System, Tokyo, Japan). Patients with heart rate above 65 bpm received 50 mg atenolol orally for 3 days prior to the MDCT scan, or they increased their usual therapy with beta-blockers, in order to obtain a prescan heart rate <60 bpm. Curved multiplanar and 3D volume reconstructions were performed to explore coronary anatomy. Results: In 235 patients, the CT scan was successful and images were appropriate for evaluation. The prevalence of myocardial bridging and intramyocardial course of coronary arteries was 18.7% (47 cases) in our patient population. In 30 segments (63.8%), the vessels ran and ended in the myocardium. In the remaining 17 segments (36.2%), the vessels returned to an epicardial position after the muscle bridge. We found no difference in the prevalence of this inborn coronary anomaly when comparing different clinical characteristics of the study population (sex, age, body-mass index [BMI], etc.). The mean length of the subepicardial artery was 7 mm (range 5-12 mm), and the mean depth in the diastolic phase was 1.9 mm (range 1.2-2.3 mm). There was no significant difference of

  11. Three-dimensional multislice CT imaging of otitis media

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, Miyako [Yanagibasi Hospital, Tokyo (Japan); Yoshikawa, Hiroshi; Hosokawa, Akira; Furukawa, Tomoyasu; Ichikawa, Ginichiro [Juntendo Univ., Tokyo (Japan). School of Medicine; Wada, Akihiro; Ando, Ichiro [Juntendo Univ., Chiba (Japan). Urayasu Hospital

    2002-07-01

    In recent years, the multislice CT system has come into practical use that enables table movement of half mm, resulting in a significant improvement in resolution. The use of this CT system enables to depict the entire auditory ossicles, including the stapes. 3D reconstruction was performed using helical CT data in 5 patients with chronic otitis media and 5 patients with cholesteatoma. An Aquilion Multi (Toshiba) multislice helical CT scanner and a Xtension (Toshiba) image workstation were used in this study. We demonstrated the 3D display with axial, coronal and sagittal images. Compared with the normal ears, it was necessary to set a higher threshold for the affected ears. It is important to select suitable threshold for demonstration of 3D images optimally. Bone destruction of the stapes was confirmed at surgery in 2 ears. The stapes was observed at 3D-CT imaging in other 18 ears. It was found that the 3D images of the ossicular destruction in ears with cholesteatoma were consistent with surgical findings. It is therefore concluded that 3D imaging of the middle ear using a multislice CT scanner is clinically useful. (author)

  12. Evaluation with low-dose dual-phase helical computed tomography of patients with thyroid lesions

    Institute of Scientific and Technical Information of China (English)

    Li Lin; Wang Yong; Zhao Yanfeng; Zou Shuangmei; Lin Meng; Yu Xiaoduo; Tang Wei

    2014-01-01

    Background The incidence of thyroid cancer has been increasing.Our aim was to evaluate the efficacy of low-dose dualphase helical computed tomography (CT) in the characterization of thyroid lesions,and to discuss the relationship between image characteristics and their pathology.Methods One hundred and six patients with thyroid lesions underwent low-dose dual-phase helical CT after the injection of contrast material.CT scans were obtained at arterial and venous phase with delays of 25 and 65 seconds,and tube current of 60 and 120 mA,respectively.The attenuation change in the lesion between the arterial and venous phase was analyzed and categorized as "increased," "decreased," "mixed" or "no change." Results Histopathologic diagnosis was obtained by surgery in 106 patients (115 lesions).Of the 106 patients,45 had nodular goiter,5 thyroid adenoma,6 thyroiditis,and 50 papillary thyroid carcinoma (PTC) (59 lesions).The attenuation value showed a significant difference (P <0.05) between the arterial and venous phase for the high attenuation area.There was statistical significant difference in terms of attenuation value in high attenuation areas at both phases and in low attenuation areas on arterial phase between nodular goiter and PTC (P <0.05).However,there was no significant difference in attenuation value between adenoma and PTC.Twenty-nine cases (76.3%) of goiter manifested mixed type,3 cases (3/5) of adenoma showed decreased type,6 cases (6/6) of thyroiditis showed increased type,and 55 cases (93.2%) of PTC showed decreased type attenuation.The sensitivity,specificity for thyroid carcinoma by dual-phase CT were 94.9% and 80.4% respectively.The overall diagnostic accuracy for thyroid lesions by dual-phase CT was 87.8%.Conclusions The performance of dual-phase helical CT is related to the pathological structure of the lesions.The analysis of enhancement patterns by using dual-phase helical CT will be helpful in the differential diagnosis of thyroid

  13. Utility of helical computed tomography to evaluate the invasion of actinomycetoma; a report of 21 cases.

    Science.gov (United States)

    Bonifaz, A; González-Silva, A; Albrandt-Salmerón, A; Padilla, M del Carmen; Saúl, A; Ponce, R María

    2008-04-01

    Actinomycetoma is a chronic infection caused by several aerobic actinomycetes; it is a relatively frequent condition in tropical countries like Mexico. It is important to be aware of the extension and depth of the disease (bone and visceral) to make the prognosis and select treatment. Our objective was to evaluate actinomycetomas using helical computed tomography (HCT) as well as its three-dimensional (3D) reconstruction. Prospective study of clinically and microbiologically proven cases of actinomycetomas, all of them recently diagnosed and untreated or unresponsive to various treatments. All patients underwent simple and contrast HCT with various helical slices of the involved zones. Then three-dimensional reconstructions on the sagittal and coronal planes were made. Twenty-one patients with actinomycetomas were included, 19 males and two females, with a mean age of 35.5 years and mean duration of disease of 4.1 years. The disease was located in the lower limbs in 81%, and in the upper limbs and trunk in 19%. Twenty of the 21 cases were caused by Nocardia brasiliensis and one by Actinomadura madurae. In all patients the disease was localized to the skin and subcutaneous tissue; 76.2% had muscular involvement; 23.8% visceral involvement; 9.5% had bone involvement and 9.5% vascular involvement. The affected area was determined in each case. HCT provides precise information about the grade of invasion at diverse levels such as visceral, muscular and vascular systems, and the calculation of the affected area.

  14. Three-dimensional helical computed tomographic evaluation of three obturation techniques: In vitro study

    Directory of Open Access Journals (Sweden)

    M Chokkalingam

    2011-01-01

    Full Text Available Aim: The purpose of this study was to evaluate the adequacy of three obturation techniques namely lateral condensation, EQ Fil (backfill obturation and thermafil (core carrier obturation techniques using three-dimensional (3D helical computed tomography (CT by volume rendering method. Materials and Methods: Thirty freshly extracted teeth were randomly divided into three groups of 10 teeth each. Biomechanical preparation was done in all the teeth using rotary instruments. All three sets of teeth were placed in helical CT slice scanner and were imaged before obturation. The three sets were then obturated by following methods: Group I: lateral condensation, Group II: EQ Fil (backfill and Group III: thermafil (core carrier obturation.Volume of the pulp chamber and gutta-percha after obturation were calculated using volume rendering technique and adequacy of the obturation techniques were calculated. Statistical Analysis Used: One-way ANOVA and Multiple-Range Tukey Test by Tukey-HSD procedure Results: Mean change in lateral condensation (0.005±0.002 was significantly higher than that of thermafil obturation (0.002±0.001 [P<0.05]. Conclusions: Conventional lateral condensation technique showed maximal inadequacy of obturation and thermafil obturation technique showed the least inadequacy of obturation when the volume of the specimens were calculated and reconstructed

  15. Development and experimental validation of a computational model for a helically coiled steam generator

    Energy Technology Data Exchange (ETDEWEB)

    Colorado, D.; Hernandez, J.A. [Centro de Investigacion en Ingenieria y Ciencia Aplicadas (CIICAp), Universidad Autonoma del Estado de Morelos (UAEM), Av. Universidad 1001, Col. Chamilpa, C.P. 62209 Cuernavaca, Morelos (Mexico); Papini, D.; Santini, L.; Ricotti, M.E. [Department of Energy, CeSNEF-Nuclear Engineering Division, Politecnico di, Milano, Via La Masa, 34, 20156, Milan (Italy)

    2011-04-15

    A computational model is developed to describe the thermo-fluid-dynamic behaviour of a helically coiled steam generator device working with water and widely adopted in the nuclear industry. The discretized governing equations are coupled using an implicit step by step method. The mathematical model includes: a subcooled liquid region, a two-phase flow region, and a superheated vapour region (according to the once-through nature of the heat exchanger). All the flow variables (enthalpies, temperatures, pressures, vapour qualities, velocities, heat fluxes, etc.), together with the thermo-physical properties, are evaluated at each point of the grid in which the domain is discretized. A full-scale experimental investigation carried out at SIET thermal-hydraulics labs in Piacenza (Italy), and aimed at characterizing the fluid-dynamic behaviour of two-phase flows in helically coiled tubes, is referenced in the present paper. Two-phase pressure drops data reduction allowed optimizing a suitable form of the friction factor multiplier required by momentum balance equation. Comparisons of the numerical simulations with a wide range of two-phase pressure drops measurements (experiments conducted both in diabatic and adiabatic conditions) are shown in order to validate the proposed model. (authors)

  16. Multi-slice spiral computed tomography assessment of cardiac diverticula%多层螺旋CT对心脏憩室的诊断价值

    Institute of Scientific and Technical Information of China (English)

    周碧; 赵静; 朱洪章; 杨有优

    2015-01-01

    目的:探讨多层螺旋CT(MSCT)在心脏憩室诊断中的临床价值。方法回顾性分析11例心脏憩室患者的临床及MSCT资料,行多种后处理技术分析心脏憩室形态表现及其他并发异常。结果11例患者心脏憩室均为单发,分别位于左心室(4例)、右心房(3例)、左心房(2例)、右心室(2例)。10例憩室呈囊袋状,1例憩室呈不规则管状,以窄颈与心腔相通,最大径2.5~8.8 cm。本组3例纤维型心室憩室壁薄、伴钙化,2例肌肉型心室憩室壁较厚。3例右心房憩室合并房间隔缺损,1例左心室憩室合并复杂心内外畸形。结论 MSCT能清楚显示心脏憩室位置、形态及大小,可为心室憩室类型判断提供依据,并能提示合并的心内外异常,是较为理想的心脏憩室非侵入性检查手段。%Objective To assess the value of multi-slice spiral computed tomography (MSCT) in the diagnosis of cardiac diverticula. Methods Cardiac MSCT of 11 patients with surgically or pathologically confirmed cardiac diverticula were retrospectively analyzed. Results The cardiac diverticula were isolated and located in the left ventricle (4), right atrium (3), left atrium (2) and right ventricle(2). The diverticula were protruding sac-like(10) or irregular tube-like(1) in shape with longitudinal diameters of 2.5-8.8 cm and were connected to the cardiac cavity by a narrow neck. The diverticular walls were unevenly thin and calcified in 3 fibrous ventricular diverticula and thick in 2 muscular diverticula..Three right atrial diverticula were associated with atrial septal defect and 1 left ventricular diverticulum was accompanied with complex malformations. Conclusion MSCT can clearly depict the location, morphology, size and type of cardiac diverticula and the associated cardiac malformation.

  17. Perforator flap transplantation assisted by the multislice spiral computed tomographic angiography: the clincal report%MSCTA辅助穿支皮瓣移植的初步报告

    Institute of Scientific and Technical Information of China (English)

    高建明; 薛峰; 夏云宝; 储旭东; 华国军; 李坤; 骆宇春; 潘功茂

    2011-01-01

    目的 探讨MSCTA在穿支皮瓣移植中应用的可行性.方法 自2009年5月~2010年9月,我们对6例小腿、足踝软组织缺损病人拟行穿支皮瓣移植修复术,术前行MSCTA检查,下肢血管三维成像,术中根据穿支皮瓣的穿支血管的位置、直径、分布情况,设计穿支皮瓣的血管蒂,皮瓣轴心线,以及皮瓣的大小,行穿支皮瓣移植手术.结果 MSCTA图像显示:2例膝上外侧动脉穿支、4例胫后动脉穿支图像清晰,而且与皮瓣移植手术中解剖穿支血管情况完全一致.2例穿支皮瓣行吻合血管游离移植,4例穿支皮瓣带蒂转移,手术顺利完成.5例皮瓣完全成活,1例皮瓣边缘坏死,1个月后皮瓣整形后愈合良好.结论 MSCTA图像在穿支皮瓣移植手术中提供有价值的解剖路径,对穿支血管显影有良好的敏感性,缩短了手术时间,明显提高手术的准确性.因此,MSCTA在穿支皮瓣移植中的应用具有良好的可行性.%Objective To investigate the potentiality of multislice spiral computed tomographic angiography(MSCTA) on preoperative planning of the perforator flap transplantation. Methods From May 2009 to September 2010, 6 cases with soft tissue defects of lower extremity, ankle and foot were treated in our department using perforator flaps. MSCTA was performed preoperatively in all patients scheduled for tissue transfer. MSCTA showed three dimensional images of blood vessels of the lower extremities and perforators. During perforator surgery, MSCTA image assessment allowed us to plan the axis, size and shape of perforator flaps according to the position, calibre and course of pedicled vessels. Results MSCTA images showed perforator vessels clearly, including lateral superior genicular artery perforating rami and posterior tibial artery perforating rami in 2 and 4 cases respectively, which was consistant to the course of perforator vessels observed during the operation. 2 cases were treated with the vascularized

  18. Eigenvalues of collective emission in multi-slice slab configurations

    Energy Technology Data Exchange (ETDEWEB)

    Friedberg, Richard [Department of Physics, Columbia University, New York, NY 10027 (United States); Manassah, Jamal T. [HMS Consultants, Inc., PO Box 592, New York, NY 10028 (United States)], E-mail: jmanassah@gmail.com

    2008-06-02

    We compute the eigenmodes of collective emission from multi-slice slab configurations, using the transfer matrix formalism. We elucidate within this formalism the phenomena of 'Invisible Gaps' in multiple-slice configuration and of 'Precocious Superradiance' in periodic structures previously observed in numerical solutions of Maxwell-Bloch equations.

  19. Paradoxical emboli: demonstration using helical computed tomography of the pulmonary artery associated with abdominal computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Delalu, P.; Ferretti, G.R.; Bricault, I.; Ayanian, D.; Coulomb, M. [Service Central de Radiologie et Imagerie Medicale, CHU Grenoble (France)

    2000-02-01

    We report the case of a 60-year-old woman with a recent history of a cerebrovascular accident. Because of clinical suspicion of pulmonary embolism and negative Doppler ultrasound findings of the lower limbs, spiral computed tomography of the pulmonary artery was performed and demonstrated pulmonary emboli. We emphasize the role of computed tomography of the abdomen, performed 3 min after the thoracic acquisition, which showed an unsuspected thrombus within the abdominal aorta and the left renal artery with infarction of the left kidney. Paradoxical embolism was highly suspected on computed tomography data and confirmed by echocardiography which demonstrated a patent foramen ovale. (orig.)

  20. Communities unfolding in multislice networks

    CERN Document Server

    Carchiolo, Vincenza; Malgeri, Michele; Mangioni, Giuseppe

    2016-01-01

    Discovering communities in complex networks helps to understand the behaviour of the network. Some works in this promising research area exist, but communities uncovering in time-dependent and/or multiplex networks has not deeply investigated yet. In this paper, we propose a communities detection approach for multislice networks based on modularity optimization. We first present a method to reduce the network size that still preserves modularity. Then we introduce an algorithm that approximates modularity optimization (as usually adopted) for multislice networks, thus finding communities. The network size reduction allows us to maintain acceptable performances without affecting the effectiveness of the proposed approach.

  1. Computer-aided diagnosis workstation and database system for chest diagnosis based on multi-helical CT images

    Science.gov (United States)

    Satoh, Hitoshi; Niki, Noboru; Mori, Kiyoshi; Eguchi, Kenji; Kaneko, Masahiro; Kakinuma, Ryutarou; Moriyama, Noriyuki; Ohmatsu, Hironobu; Masuda, Hideo; Machida, Suguru; Sasagawa, Michizou

    2006-03-01

    Multi-helical CT scanner advanced remarkably at the speed at which the chest CT images were acquired for mass screening. Mass screening based on multi-helical CT images requires a considerable number of images to be read. It is this time-consuming step that makes the use of helical CT for mass screening impractical at present. To overcome this problem, we have provided diagnostic assistance methods to medical screening specialists by developing a lung cancer screening algorithm that automatically detects suspected lung cancers in helical CT images and a coronary artery calcification screening algorithm that automatically detects suspected coronary artery calcification. We also have developed electronic medical recording system and prototype internet system for the community health in two or more regions by using the Virtual Private Network router and Biometric fingerprint authentication system and Biometric face authentication system for safety of medical information. Based on these diagnostic assistance methods, we have now developed a new computer-aided workstation and database that can display suspected lesions three-dimensionally in a short time. This paper describes basic studies that have been conducted to evaluate this new system. The results of this study indicate that our computer-aided diagnosis workstation and network system can increase diagnostic speed, diagnostic accuracy and safety of medical information.

  2. Simultaneous multislice (SMS) imaging techniques

    NARCIS (Netherlands)

    Barth, M.; Breuer, F.; Koopmans, P.J.; Norris, David Gordon; Poser, B.A.

    2016-01-01

    Simultaneous multislice imaging (SMS) using parallel image reconstruction has rapidly advanced to become a major imaging technique. The primary benefit is an acceleration in data acquisition that is equal to the number of simultaneously excited slices. Unlike in-plane parallel imaging this can have

  3. Assessment of the relationship between stenosis severity and distribution of coronary artery stenoses on multislice computed tomographic angiography and myocardial ischemia detected by single photon emission computed tomography

    Science.gov (United States)

    Tamarappoo, Balaji K.; Gutstein, Ariel; Cheng, Victor Y.; Nakazato, Ryo; Gransar, Heidi; Dey, Damini; Thomson, Louise E. J.; Hayes, Sean W.; Friedman, John D.; Germano, Guido; Slomka, Piotr J.

    2010-01-01

    Background The relationship between luminal stenosis measured by coronary CT angiography (CCTA) and severity of stress-induced ischemia seen on single photon emission computed tomographic myocardial perfusion imaging (SPECT-MPI) is not clearly defined. We sought to evaluate the relationship between stenosis severity assessed by CCTA and ischemia on SPECT-MPI. Methods and Results ECG-gated CCTA (64 slice dual source CT) and SPECT-MPI were performed within 6 months in 292 patients (ages 26-91, 73% male) with no prior history of coronary artery disease. Maximal coronary luminal narrowing, graded as 0, ≥25%, 50%, 70%, or 90% visual diameter reduction, was consensually assessed by two expert readers. Perfusion defect on SPECT-MPI was assessed by computer-assisted visual interpretation by an expert reader using the standard 17 segment, 5 point-scoring model (stress perfusion defect of ≥5% = abnormal). By SPECT-MPI, abnormal perfusion was seen in 46/292 patients. With increasing stenosis severity, positive predictive value (PPV) increased (42%, 51%, and 74%, P = .01) and negative predictive value was relatively unchanged (97%, 95%, and 91%) in detecting perfusion abnormalities on SPECT-MPI. In a receiver operator curve analysis, stenosis of 50% and 70% were equally effective in differentiating between the presence and absence of ischemia. In a multivariate analysis that included stenosis severity, multivessel disease, plaque composition, and presence of serial stenoses in a coronary artery, the strongest predictors of ischemia were stenosis of 50-89%, odds ratio (OR) 7.31, P = .001, stenosis ≥90%, OR 34.05, P = .0001, and serial stenosis ≥50% OR of 3.55, P = .006. Conclusions The PPV of CCTA for ischemia by SPECT-MPI rises as stenosis severity increases. Luminal stenosis ≥90% on CCTA strongly predicts ischemia, while stenosis strongly predicts the absence of ischemia. Serial stenosis of ≥50% in a vessel may offer incremental value in addition to

  4. The role of multislice spiral computed tomography in the diagnosis and management of acute facial trauma in patients with multiple injuries.

    Science.gov (United States)

    Nemsadze, G; Urushadze, O

    2011-11-01

    Using of mutislice spiral CT as first line examination for the diagnosis of Acute Facial trauma in the setting of Polytrauma reduces both: valuable time and cost of patient treatment. After a brief clinical examination, MDCT was performed depending on the area of injury, using a slice thickness of 0.65 mm. The obtained data were analyzed using 3D, MIP and Standard axial with Bone reconstruction protocols. 64 polytrauma patients were evaluated with both Anterior and Lateral craniography (plain skull X ray: AP and Lateral) and Multi Slice CT. Craniography detected only 18 cases of traumatic injuries of facial bones, but exact range of dislocation and accurate management plan could not be established. In the same 64 cases, Multislice CT revealed localization of all existed fractures, range of fragment dislocation, soft tissue damage and status of Paranasal sinus in 62 cases (96.8%). In two cases MS CT missed the facial fracture, in one case the examination was complicated because of bone thinness and numerous fracture fragments, in another multiple foreign body artifacts complicated the investigation. The study results show that, CT investigation based on our MDCT polytrauma protocol, detects all more or less serious facial bone injuries.

  5. Clinical evaluation of flat-panel detector compared with multislice computed tomography in 65 patients with acute intracranial hemorrhage: initial results. Clinical article.

    Science.gov (United States)

    Struffert, Tobias; Eyupoglu, Ilker Y; Huttner, Hagen B; Engelhorn, Tobias; Doelken, Marc; Saake, Marc; Ganslandt, Oliver; Doerfler, Arnd

    2010-10-01

    The goal in this study was to compare flat-panel detector (FD) CT with multislice (MS) CT in the visualization of intracerebral hemorrhage (ICH), subarachnoid hemorrhage (SAH), intraventricular hemorrhage, and external ventricular drains (EVDs) to evaluate the diagnostic quality and limitations of the new FD CT imaging modality. Neuroimages obtained in 65 patients, including 24 with EVDs, were reviewed by 2 independent, experienced clinicians. Lesions in all patients were investigated with FD CT and MS CT. The numbers of slices positive for ICH and SAH were counted, and for ICH the diameter and area of the lesion was measured. The positioning of drains was assessed. The presence of ventricular blood was noted. Statistical analysis was performed by calculating the Pearson correlation coefficient (r) to evaluate the level of inter- and intraobserver agreement, and linear regression analysis was done to visualize the results of the numbers of ICH- and SAH-positive slices. The authors found high interobserver agreement regarding the number of slices with evidence of ICH (r = 0.89 for MS CT, r = 0.78 for FD CT) and SAH (r = 0.88 for MS CT, r = 0.9 for FD CT). Thin layers of blood in the ventricles were not detected on FD CT in 36.4% of cases. Six of 7 perimesencephalic SAHs were not seen on FD CT scans. The EVDs could be assessed with both modalities in 83.3% of cases, but the position of the drain could not be determined with FD CT in 16.7% (4 of 24 cases). In some respects, FD CT is of limited use for the visualization of intracranial hemorrhage. However, despite limited contrast resolution, ICH and EVDs can be reliably demonstrated. Perimesencephalic SAH and thin layers of blood in the occipital horns may not be detected using FD CT. Further evaluation and improvement of the image quality is necessary before FD CT will provide identical quality in comparison with MS CT.

  6. Pulmonary artery aneurysm in Bechcet's disease: helical computed tomography study; Aneurisma de la arteria pulmonar en la enfermedad de Behcet. Estudio con tomografia computarizada helicoidal

    Energy Technology Data Exchange (ETDEWEB)

    Munoz, J.; Caballero, P.; Olivera, M. J.; Cajal, M. L.; Caniego, J. L. [Hospital de la Princesa. Iniversidad Autonoma. Madrid (Spain)

    2000-07-01

    Behcet's disease is a vasculitis of unknown etiology that affects arteries and veins of different sizes and can be associated with pulmonary artery aneurysms. We report the case of a patient with Behcet's disease and a pulmonary artery aneurysm who was studied by means of plain chest X ray, helical computed tomography and pulmonary arteriography. Helical computed tomography is a reliable technique for the diagnosis and follow-up of these patients. (Author) 9 refs.

  7. A More Accurate and Efficient Technique Developed for Using Computational Methods to Obtain Helical Traveling-Wave Tube Interaction Impedance

    Science.gov (United States)

    Kory, Carol L.

    1999-01-01

    The phenomenal growth of commercial communications has created a great demand for traveling-wave tube (TWT) amplifiers. Although the helix slow-wave circuit remains the mainstay of the TWT industry because of its exceptionally wide bandwidth, until recently it has been impossible to accurately analyze a helical TWT using its exact dimensions because of the complexity of its geometrical structure. For the first time, an accurate three-dimensional helical model was developed that allows accurate prediction of TWT cold-test characteristics including operating frequency, interaction impedance, and attenuation. This computational model, which was developed at the NASA Lewis Research Center, allows TWT designers to obtain a more accurate value of interaction impedance than is possible using experimental methods. Obtaining helical slow-wave circuit interaction impedance is an important part of the design process for a TWT because it is related to the gain and efficiency of the tube. This impedance cannot be measured directly; thus, conventional methods involve perturbing a helical circuit with a cylindrical dielectric rod placed on the central axis of the circuit and obtaining the difference in resonant frequency between the perturbed and unperturbed circuits. A mathematical relationship has been derived between this frequency difference and the interaction impedance (ref. 1). However, because of the complex configuration of the helical circuit, deriving this relationship involves several approximations. In addition, this experimental procedure is time-consuming and expensive, but until recently it was widely accepted as the most accurate means of determining interaction impedance. The advent of an accurate three-dimensional helical circuit model (ref. 2) made it possible for Lewis researchers to fully investigate standard approximations made in deriving the relationship between measured perturbation data and interaction impedance. The most prominent approximations made

  8. 口腔颌面锥形束CT与螺旋CT辐射剂量的比较研究%Comparative dosimetry of dental cone-beam computed tomography and multi-slice computed tomography for oral and maxillofacial radiology

    Institute of Scientific and Technical Information of China (English)

    曲兴民; 李刚; 张祖燕; 马绪臣

    2011-01-01

    Objective To compare the effective radiation dose levels of cone beam computed tomography (CBCT) with those of multi-slice computed tomography (MSCT) when scanning the same maxillofacial regions.Methods The effective doses of 2 CBCT( NewTom 9000 and DCT Pro) and 1 MSCT (bright speed edge select 8 slice) scanners were calculated using thermoluminescent dosimeters (TLD) that were placed in a head and neck phantom,and expressed according to the International Commission on Radiation Protection(ICRP) 2007 guidelines.Results Effective dose values ranged from 41.8 to 249.1 μSv for CBCT.The doses of MSCT scanning for maxilla,mandible and maxilla + mandible were 506.7,829.9 and 1066.1 μSv,respectively.Dose levels of scanning only for maxilla or mandible were significantly lower than those for maxilla + mandible.Conclusions When scanning the same maxillofacial regions,the dose levels for NewTom 9000 and DCT Pro CBCT images were lower than those for Bright speed edge select 8 slice MSCT images.Dose levels reduction could be obtained when smaller regions were scanned.%目的 比较口腔颌面锥形束CT与螺旋CT在扫描口腔颌面部相同部位时的辐射剂量,为临床安全有效应用提供实验数据.方法 使用热释光剂量芯片测量两种口腔颌面锥形束CT和一种螺旋CT在扫描头颈部体模上颌、下颌、上颌+下颌时的吸收剂量.按照国际放射防护委员会2007年推荐的组织权重因子,计算各个扫描程序的有效剂量.使用单因素方差分析对所有扫描程序得到的有效剂量进行比较分析,P<0.05为差异有统计学意义.结果 两种口腔颌面锥形束CT的辐射剂量范围41.8 ~249.1 μSv.螺旋CT对上颌、下颌及上颌+下颌进行扫描时的有效剂量分别为506.7、829.9和1066.1 μSv,螺旋CT辐射剂量显著高于两种口腔颌面锥形束CT(P <0.001).同一机型仅进行上颌或下颌扫描的辐射剂量显著低于同时扫描上颌+下颌时

  9. Rol de la TC multicorte en las hernias diafragmáticas: Ensayo iconográfico Role of Multislice Computed Tomography in the evaluation of diaphragmatic hernias: Pictorial essay

    Directory of Open Access Journals (Sweden)

    Mario G. Santamarina

    2009-12-01

    Full Text Available Las hernias diafragmáticas consisten en la migración de estructuras abdominales hacia el tórax a través de un defecto del diafragma. Ellas pueden tener origen congénito (de Morgagni y de Bochdalek o adquirido, incluyendo las traumáticas o no traumáticas (del hiato, defectos diafragmáticos posteriores. Debido a que en algunas hernias diafragmáticas está indicada la reparación quirúrgica, los métodos de diagnóstico por imágenes cumplen un rol fundamental. La TC multicorte, con su capacidad multiplanar y posibilidad de efectuar cortes finos, nos permite valorar y caracterizar adecuadamente el defecto diafragmático y sus complicaciones. En este ensayo iconográfico realizamos un breve repaso de la embriología y anatomía del diafragma, revisamos los distintos tipos de hernias diafragmáticas y la utilidad de la TC multicorte.Diaphragmatic hernias are characterized by the migration of abdominal structures into the chest through a diaphragmatic defect. These may have either a congenital etiology (e.g., Morgagni and Bochdalek, or an acquired etiology, including traumatic and nontraumatic hernias (hiatal, posterior diaphragmatic defects. Since a surgical repair is indicated in certain types of hernias, imaging diagnostic methods play a key role. Multislice Computed Tomography (MSCT allows multiplanar views and thin section evaluation, thus providing a useful tool for the assessment and characterization of the diaphragmatic defect and its complications. In this pictorial essay we briefly review the diaphragm anatomy and embryology, the different types of diaphragmatic hernias and the role of MSCT.

  10. Role of high resolution multislice CT scan in otosclerosis

    Directory of Open Access Journals (Sweden)

    Atef EL Maraghy

    2015-11-01

    Full Text Available This prospective study was carried out to assess the radiological findings in patients with otosclerosis using high resolution multislice CT scan and to correlate these findings with audiological findings in those patients. This study was done at Al Azhar University hospitals during the period from Jan 2012 to Jun 2014. Thirty-two patients were enrolled in this study; 13 (40.63% males and 19 (59.37% females. Their age ranged from 13 to 55 with a mean of 36.21 ± 8.7 years. Written consent was taken from all patients. Multislice CT scan was done to all patients and reports were done by computer assisted analysis with thorough audiological assessment including pure tone audiometry, tympanometry and stapedial reflex. Positive findings were present in 40/58 ears (69% while negative findings were present in 18/58 ears (31%. Otosclerotic foci were more detected when slice thickness was lesser than one millimeter especially at fissula ante fenestrum and round window region. There was a good correlation between air bone gap and CT score (p = 0.002. High resolution multislice CT helps in the diagnosis of otosclerosis with sensitivity (69% and it aids in the diagnosis of doubtful cases. Otosclerosis has a special predilection to affect certain sites mainly the fissula ante fenestrum followed by the round window and the cochlear promontory.

  11. 胃间质瘤MSCT诊断及临床应用价值%Diagnosis and clinical value of multi-slice spiral computed tomography in gastrointestinal stromal tumor

    Institute of Scientific and Technical Information of China (English)

    李小龙; 杨铁; 王巍; 卓家驹; 刘刚; 吴坚

    2013-01-01

    Objective To discuss the diagnostic value and clinical application value of multi-slice spiral computed tomography about gastrointestinal stromal tumor.Methods We analyze 38 cases with stomach stromal tumor which are confirmed by pathology and immunohistochemistry retrospectively,observe the size,shape,density,reinforcement of lesion or focus and other organ invaded and secondary changes,and decide that it is benign tumor or malignant tumor.Results The maximum diameter of tumor is smaller than 5 cm (4 cases),the maximum diameter of tumor is from 5 cm to 10 cm (22 cases),the maximum diameter of tumor is bigger than 10 cm (12 cases).There is necrosis and cystic change (13 cases) and hemorrhage (8 cases) in the lesion.The normal membrana mucosa is not existed in the gastral cavity (10 cases).The focus is communicated with gastral cavity because of ulcer formation (8 cases) but there is not any ulcer of stomach although air is in gastral cavity (2 cases).It is asymmetry reinforcement of the tumor and the center of the focus is without any reinforcement sometime.The tumor has adhesion to tissue or organ around it (28 cases).The preoperative diagnoses are benign tumor (5 cases),anaplastic tumor or borderline tumors (23 cases),malignant tumor (10 cases) according to size,density and contiguity.Conclusion It is possible to display stomach stromal tumor focus by multi-slice spiral computed tomography definitely and to supply effective information about diagnosis and grading.Image of multi-slice spiral computed tomography is effective measure about preoperative evaluation and postoperative follow-up and curative effect assessment to stomach stromal tumor.It is effective supplement of endoscopy.%目的 探讨多层螺旋CT对胃间质瘤的诊断价值及临床应用价值.方法 回顾性分析经手术病理学及免疫组织化学证实的胃间质瘤患者38例,观察其病灶大小、形态、密度、病灶强化特点、肿瘤累及范围以及其他继发改变

  12. Imaging of Blood Flow in Cerebral Arteries with Dynamic Helical Computed Tomography Angiography (DHCTA) Using a 64-Row CT Scanner

    Energy Technology Data Exchange (ETDEWEB)

    Pekkola, J.; Kangasniemi, M. (Helsinki Medical Imaging Center, Helsinki Univ. Central Hospital, Helsinki (Finland))

    2009-08-15

    Background: Cerebral computed tomography angiography (CTA) depicts a structural image of intracranial arteries without providing much time-resolved information on blood flow dynamics. Current CT technology allows obtaining of rapidly repeated helical scans during the arterial contrast filling phase after an intravenous contrast injection. Purpose: To report our experience on dynamic CT imaging in determining the direction of contrast filling within proximal intracranial arteries of operated cerebral artery aneurysm patients. Such dynamic information can help detect vascular occlusion or severe spasm. The method is here referred to as dynamic helical CT angiography (DHCTA). Material and Methods: We retrospectively collected image and related technical data for 23 patients who underwent DHCTA and CTA during their first postoperative day after cerebral artery aneurysm surgery. For DHCTA, we had helically scanned a 4-cm tissue volume three times in succession with a 64-row CT scanner at intervals of 2.6 s during arterial contrast filling after an intravenous contrast injection. We assessed how well DHCTA succeeded in demonstrating the direction of contrast filling in the proximal intracranial arteries, evaluated clinically relevant structural information provided by DHCTA and CTA, and compared radiation doses for the two methods. Results: For 21 patients, DHCTA outlined the direction of contrast filling in proximal intracranial arteries. As to arterial spasm and residual filling of the operated aneurysm, CTA and DHCTA gave similar information. Radiation doses were higher (P<0.000001) for DHCTA than for CTA at 120 kV tube voltage. At 100 kV, the difference was smaller, but doses for DHCTA still exceeded (P<0.05) those for CTA. Conclusion: DHCTA gave dynamic information unobtainable with CTA and could prove useful in selected clinical settings

  13. Radiation dose in computed tomography of the pelvis: comparison of helical and axial scanning.

    Science.gov (United States)

    Pitman, A G; Budd, R S; McKenzie, A F

    1997-11-01

    An anthropomorphic Rando phantom was used to compare radiation doses sustained during helical and conventional axial CT of the pelvis. The values obtained with the Rando phantom were validated against cadaveric phantoms, and show good agreement. For the authors' particular CT unit, helical scanning was found to deliver a lower radiation dose than conventional axial scanning. This was most prominent at 1.0-s tube rotation times (average dose ratio 1.24). For realistic scanning parameters and exposure factors, the ratio of radiation dose to pelvic organs can be expected to lie in the range of 40-100 mGy. The whole-body effective dose (ED) depends on selection of scanning parameters and patients anatomy. In a favourable case scenario, the ED for CT scanning of the pelvis in a male can be expected to be between 10 and 20 mSv if the scrotum is not included in the radiation field, while the ED in a female will be approximately 20 mSv. An examination of scatter radiation fall-off curves from a single slice shows that the spread of scatter radiation is only marginally affected by slice thickness. A total of 10-12 cm of human soft tissue acts as a good barrier against internal scattered radiation. The use of such scatter fall-off curves, together with manufacturers' dosimetry specifications, allows a fast estimate of absorbed dose.

  14. Follow-up after stent insertion in the tracheobronchial tree: role of helical computed tomography in comparison with fiberoptic bronchoscopy

    Energy Technology Data Exchange (ETDEWEB)

    Ferretti, G.R.; Kocier, M.; Calaque, O.; Coulomb, M. [Service Central de Radiologie et Imagerie Medicale, INSERM EMI 9924, CHU, BP 217, 38043, Grenoble Cedex 9 (France); Arbib, F.; Pison, C. [Departement de Medecine Aigue Specialisee (DMAS), CHU Grenoble, CHU, BP 217, 38043, Grenoble Cedex 9 (France); Righini, C. [Service d' Oto Rhino Laryngologie, CHU Grenoble, BP 217, 38043, Grenoble Cedex 9 (France)

    2003-05-01

    The aim of this study was to compare helical CT with fiberoptic bronchoscopy findings to appraise the medium-term results of proximal-airways stenting. Twenty-five patients with 28 endobronchial metallic stents inserted for local advanced malignancy (n=13) or benign diseases (n=12) underwent follow-up CT from 3 days to 50 months (mean 8 months). All studies were obtained using helical CT with subsequent multiplanar reformation and three-dimensional reconstruction including virtual bronchoscopy. The location, shape, and patency of stents and adjacent airway were assessed. The results of CT were compared with the results of fiberoptic bronchoscopy obtained with a mean delay of 2.5 days (SD 9 days) after CT scan. Twelve stents (43%) remained in their original position, patent and without deformity. Sixteen stents were associated with local complications: migration (n=6); external compression with persistent stenosis (n=4); local recurrence of malignancy (n=4); fracture (n=1); and non-congruence between the airway and the stent (n=1). The CT demonstrated all the significant abnormalities demonstrated at fiberoptic bronchoscopy except two moderate stenoses (20%) related to granulomata at the origin of the stent. Ten of 14 stents inserted for benign conditions were without complications as compared with 2 of 14 in malignant conditions (p=0.008). Computed tomography is an accurate noninvasive method for evaluating endobronchial stents. The CT is a useful technique for follow-up of patients who have undergone endobronchial stenting. (orig.)

  15. Intrinsic α-helical and β-sheet conformational preferences: a computational case study of alanine.

    Science.gov (United States)

    Caballero, Diego; Määttä, Jukka; Zhou, Alice Qinhua; Sammalkorpi, Maria; O'Hern, Corey S; Regan, Lynne

    2014-07-01

    A fundamental question in protein science is what is the intrinsic propensity for an amino acid to be in an α-helix, β-sheet, or other backbone dihedral angle ( ϕ-ψ) conformation. This question has been hotly debated for many years because including all protein crystal structures from the protein database, increases the probabilities for α-helical structures, while experiments on small peptides observe that β-sheet-like conformations predominate. We perform molecular dynamics (MD) simulations of a hard-sphere model for Ala dipeptide mimetics that includes steric interactions between nonbonded atoms and bond length and angle constraints with the goal of evaluating the role of steric interactions in determining protein backbone conformational preferences. We find four key results. For the hard-sphere MD simulations, we show that (1) β-sheet structures are roughly three and half times more probable than α-helical structures, (2) transitions between α-helix and β-sheet structures only occur when the backbone bond angle τ (NCα C) is greater than 110°, and (3) the probability distribution of τ for Ala conformations in the "bridge" region of ϕ-ψ space is shifted to larger angles compared to other regions. In contrast, (4) the distributions obtained from Amber and CHARMM MD simulations in the bridge regions are broader and have increased τ compared to those for hard sphere simulations and from high-resolution protein crystal structures. Our results emphasize the importance of hard-sphere interactions and local stereochemical constraints that yield strong correlations between ϕ-ψ conformations and τ.

  16. Helicity scalings

    Energy Technology Data Exchange (ETDEWEB)

    Plunian, F [ISTerre, CNRS, Universite Joseph Fourier, Grenoble (France); Lessinnes, T; Carati, D [Physique Statistique et Plasmas, Universite Libre de Bruxelles (Belgium); Stepanov, R, E-mail: Franck.Plunian@ujf-grenoble.fr [Institute of Continuous Media Mechanics of the Russian Academy of Science, Perm (Russian Federation)

    2011-12-22

    Using a helical shell model of turbulence, Chen et al. (2003) showed that both helicity and energy dissipate at the Kolmogorov scale, independently from any helicity input. This is in contradiction with a previous paper by Ditlevsen and Giuliani (2001) in which, using a GOY shell model of turbulence, they found that helicity dissipates at a scale larger than the Kolmogorov scale, and does depend on the helicity input. In a recent paper by Lessinnes et al. (2011), we showed that this discrepancy is due to the fact that in the GOY shell model only one helical mode (+ or -) is present at each scale instead of both modes in the helical shell model. Then, using the GOY model, the near cancellation of the helicity flux between the + and - modes cannot occur at small scales, as it should be in true turbulence. We review the main results with a focus on the numerical procedure needed to obtain accurate statistics.

  17. Application of computational chemistry methods to the prediction of chirality and helical twisting power in liquid crystal systems

    Science.gov (United States)

    Noto, Anthony G.; Marshall, Kenneth L.

    2005-08-01

    Until recently, it has not been possible to determine, with any real certainty, a complete picture of "chirality" (absolute configuration, optical rotation direction, and helical twisting power) for new chiral compounds without first synthesizing, purifying, characterizing, and testing every new material. Recent advances in computational chemistry now allow the prediction of certain key chiral molecular properties prior to synthesis, which opens the possibility of predetermining the "chiroptical" properties of new liquid crystal dopants and mixtures for advanced optical and photonics applications. A key element to this activity was the development of both the chirality index (G0) by Osipov et al., and the scaled chirality index (G0S) by Solymosi et al., that can be used as a "figure of merit" for molecular chirality. Promising correlations between G0S and both circular dichroism (CD) and the helical twisting power (HTP) of a chiral dopant in a liquid crystal host have been shown by Neal et al., Osipov, and Kuball. Our work improves the predictive capabilities of G0S by taking into account the actual mass of each atom in the molecule in the calculations; in previous studies the mass of each atom was assumed to be equal. This "weighted" scaled chirality index (G0SW) was calculated and correlated to existing experimental HTP data for each member of a series of existing, well-known chiral compounds. The computed HTP using G0SW for these model systems correlated to the experimental data with remarkable accuracy. Weighted, scaled chiral indices were also calculated for the first time for a series of novel chiral transition metal dithiolene dyes for near-IR liquid crystal device applications.

  18. 64-multislice detector computed tomography coronary angiography as potential alternative to conventional coronary angiography: a systematic review and meta-analysis

    DEFF Research Database (Denmark)

    Abdulla, Jawdat; Abildstrom, Steen Z.; Gøtzsche, Ole

    2007-01-01

    coronary artery stenosis in per-segment (19 studies) and per-patients (13 studies) populations were 19 and 57.5% respectively. Accuracy tests with 95% confidence intervals comparing 64-SCTA vs. CCA showed that sensitivity, specificity, positive predictive and negative predictive values for native coronary......% by overall per-segment analysis. CONCLUSION: The high diagnostic accuracy of 64-SCTA validates this non-invasive technique as a potential alternative to CCA in carefully selected populations suspected for coronary stenosis. Udgivelsesdato: 2007-Dec......AIMS: To evaluate the diagnostic accuracy of 64-slice multi-detector computed tomography coronary angiography (64-SCTA) compared with the standard reference conventional coronary angiography (CCA). METHODS AND RESULTS: Based on a systematic search, 27 studies including 1740 patients were eligible...

  19. On-line multi-slice computed tomography interactive overlay with conventional X-ray: a new and advanced imaging fusion concept.

    Science.gov (United States)

    Garcia, Joel A; Bhakta, Shyam; Kay, Joseph; Chan, Kak-Chen; Wink, Onno; Ruijters, Danny; Carroll, John D

    2009-04-17

    Computed tomography (CT) has revolutionized noninvasive cardiovascular evaluations. Complicated percutaneous procedures require precise imaging guidance that conventional X-ray is often unable to provide. By combining X-ray imaging with real-time, interactive, CT-based landmarks, interventional procedures could be facilitated. We describe two cases using the first CT/Live X-ray overlay in which this technology shows its potential. A 31-year-old male with an anatomically complicated atrial septal defect (ASD) was referred for percutaneous closure. Transesophageal echocardiography (TEE) revealed an inferior location of the ASD complicated by it's proximity to a prominent Eustachian ridge. The CT was used to create a patient-specific physical model in preparation for the procedure and an in-lab real-time CT overlay allowing successful closure. A second case of a 41-year-old male with coronary artery disease status-post coronary artery bypass, aortic valve replacement (AVR), and aortic root replacement with an abnormal coronary computed tomography angiogram (CTA). In a prior procedure years ago the saphenous vein graft (SVG) to the left anterior descending artery (LAD) could not be cannulated during invasive angiography, given the patient's complicated and unusual anatomy. Using CT overlay, the superiorly and anteriorly located SVG was cannulated successfully. CT/Live X-ray overlay provided an adequate anatomical intra-procedural ASD evaluation, defect sizing, and guidance in one case and localization of an anatomically challenging graft ostium in the other case. Adding the CT landmarks as an overlay to traditional X-ray techniques provides a revolutionary and advanced imaging fusion concept that should improve procedural success.

  20. Comparative analysis of multi-slice computer tomography enterography (MSCTE) and digestive endoscopy on the involved site of Crohn disease%MSCTE与消化内镜检查发现Crohn病累及部位的比较分析

    Institute of Scientific and Technical Information of China (English)

    张燕红; 叶文卫; 陈毅斌; 张锡迎; 杨宇峰; 刘琴

    2016-01-01

    目的:探讨多层螺旋CT口服小肠造影(MSCTE)与消化内镜检查发现Crohn病累及部位的临床价值。方法选取两家医院临床随访证实为 Crohn 病患者30例,行消化内镜检查为 A组,行MSCTE检查为B组,A、B两组发现Crohn病累及部位进行比较分析。结果 A组无异常6例,累及单独小肠5例,小肠及结直肠10例,单独结直肠9例;B组累及单独小肠14例,小肠及结直肠9例,单独结直肠7例。A、B两组发现Crohn病累及部位的比较有统计学意义(P<0.05)。结论 MSCTE诊断Crohn病累及部位较消化内镜具有更高的临床价值。%ObjectiveThe aim of the present study was to evaluate the clinical value of multi-slice computer tomography enterography (MSCTE) and digestive endoscopy on the involved site of Crohn disease(CD).MethodsSelected 30 patients with CD from two hospitals confirmed by clinical follow-up. Digestive endoscopy as group A, MSCTE examination as group B, involved site of two groups of CD were compared and analyzed.ResultsIn group A, 6 cases had been found normal, 5 cases had been found that lesion site was in the small intestine, 10 cases in the small intestine and colorectal, 9 cases only in the colorectal. In group B, 14 cases had been found the lesion site was in the small intestine only, 9 cases in the small intestine and colorectal, 7 cases in the colorectal only. There had statistical significance between group A and group B (P<0.05).ConclusionThe MSCTE has higher clinical value to diagnose the involved site of CD.

  1. COMPARATIVE ROLE AND EVALUATION OF ULTRASOUND AND MULTISLICE COMPUTED TOMOGRAPHY IN THE GRADING OF HEMOPERITONEUM IN PATIENTS WITH ACUTE BLUNT ABDOMINAL TRAUMA AND ITS CORRELATION WITH THE GRADING OF ORGAN INJURY

    Directory of Open Access Journals (Sweden)

    Kunwarpal

    2015-06-01

    Full Text Available AIMS AND OBJECTIVES: 1. To assess the role of Ultrasound (US and Multislice Computed Tomography (MSCT in detecting hemoperitoneum in patients with acute blunt abdominal trauma. 2. To study the use of US and MSCT in grading of hemoperitoneum in blunt abdominal trauma patients. 3. To compare the US and MSCT grading of hemoperitoneum with the grading of organ injury. 4. To compare and statistically analyze the spectrum of findings observed in each modality. MATERIAL AND METHODS: The study was conducted at advanced diagnostics and institute of imaging , Amritsar. The study comprised of 50 patients who were stable enough to undergo both US and CT scans.US was preceded by MSCT in most of the patients and the time gap between the imaging modalities was less than 1 hour to make the study comparable. TECHNIQUES ADOPTED : 1. US was performed on Versa plus (Siemens and Xario (Toshiba with Cardiac , 3.5 - 5 Mhz - Convex and 5 - 7.5 Mhz - Line ar probes. Particular attention was paid to the amount of free fluid in the abdomen and pelvis. 2. MSCT was performed with MSCT Volume Zoom (Siemens Forchheim Germany AG. 500 - 1000cc of water orally or through nasogastric tube was given 15 - 20 minutes before the study , followed by 120cc I/V contrast at the rate of 2 - 3ml/second using power injector. Parameters used: Single breath hold ; A. 165 mAs . B. 120 kvp . C. Scan delay - 40 seconds . D. Collimation - 4x2.5mm . E. Pitch - 5mm . Following findings were observed : a. Presence of peritoneal fluid. B. Any tear or hematoma in the solid abdominal organs like spleen and liver. C. Status of hollow viscera like small bowel , large bowel and urinary bladder. Hemoperitoneum was scored on both US and MSCT. Visceral injuries were graded according to O.I.S grading system. Score was correlated with the underlying organ injury and the management of the patient. US scoring (Table A and MSCT quantification of hemoperitoneum was done. (Table B Location of hemoperitoneum . A

  2. Unsupervised motion-compensation of multi-slice cardiac perfusion MRI

    DEFF Research Database (Denmark)

    Stegmann, M.B.; Ólafsdóttir, H; Larsson, H.B.W.

    2005-01-01

    This paper presents a novel method for registration of single and multi-slice cardiac perfusion MRI. Utilising off-line computer intensive analyses of variance and clustering in an annotated training set, the presented method is capable of providing registration without any manual interaction...

  3. The Comparison of Ultrasonography and Non Enhanced Helical Computed Tomography in the Diagnosis of Ureteral Calculi

    Directory of Open Access Journals (Sweden)

    İlhan Kılınç

    2007-01-01

    Full Text Available Intravenous urography, ultrasonography, and non-contrast spiral computed tomography have been used to diagnose ureteral calculi. We aimed to compare the accuracy of non-contrast spiral computed tomography with ultrasonography in the evaluation of patients with renal colic.Fourty-one patients with flank pain were examined with both computed tomography and ultrasonography over a period of 11 months. Findings of ultrasonography and computed tomography of 28 patients in whom üreteral stones were confirmed by standart methods were comparedUreteral calculi were diagnosed in 28 of 41 patients. Ureteral stones could be demonstrated in 18 patients by ultrasonography and in 27 patients by computed tomography. Ultrasonography showed 64.3% sensitivity and 100% specificity in the diagnosis of ureterolithiasis; computed tomography showed 96.4% and 100%, respectively. Spiral computed tomography is superior to ultrasonography in the demonstration of ureteral calculi in patients with renal colic. But because of higher cost and higher radiation dose, it should be reserved for symptomatic cases in whom ultrasonography is non-diagnostic.

  4. 多层螺旋CT血管造影在胃癌规范性根治术术前评估中的价值%Preoperative Evaluation Value of Multislice Spiral Computed Tomography Angiography for Normative Radical Gastrectomy

    Institute of Scientific and Technical Information of China (English)

    刘超; 黄源; 林进令

    2011-01-01

    Objective To explore the evaluation value of preoperative multislice spiral computed tomography angiography (MSCTA) for normative radical gastrectomy. Methods The anatomic distributions of celiac trunk and its three branches and their tributaries (common hepatic artery, right hepatic artery, left hepatic artery, splenic artery, and left gastric artery) of 86 patients with gastric cancer were comprehended by preoperative MSCTA, which were verified during the surgery. Simultaneously preoperative TNM staging was evaluated by MSCTA, which compared with postoperative pathological results. Results The accuracy rate of preoperative MSCTA evaluating the distribution of celiac trunk and its three branches and their tributaries was 100%. Abnormal hepatic arteries were found in 22 cases by MSCTA, the mutation rate was 25.58%. Abnormal right hepatic arteries were found in 11 cases (12.79%), abnormal left hepatic arteries in 7 cases (8.14%), both abnormal right and left hepatic arteries in 1 case (1.16%), and abnormal common hepatic arteries in 3 cases (3.49%). Straight splenic arteries were found in 24 cases (27.91% ), slightly curved splenic arteries in 44 cases (51.16 % ), and significantly curved splenic arteries in 18 cases (20. 93 % ). Compared with postoperative pathological results, the accuracy rates of preoperative MSCTA evaluating gastric cancer T, N, and M staging were 75.58% (65/86), 74.42% (64/86), and 91.86% (79/86), respectively. Conclusions Preoperative MSCTA is an objective way to assess the distributions of celiac artery trunk and related tributaries of patients with gastric cancer. Also, it is an accurate method to evaluate the preoperative TNM stage of gastric cancer, which can help to make an individual operative plan and avoid the intraoperative injury of the artery.%目的 探讨多层螺旋CT血管造影(multislice spiral computed tomography angiography,MSCTA)在胃癌规范性根治术术前评估中的价值.方法

  5. A Experimental and Computational Study of Flow Instability in a Helical Coil.

    Science.gov (United States)

    Webster, Donald Robert

    This study concerns the transitional regime between laminar and turbulent flow states in a helically coiled pipe of circular cross-section. The study consists of complementary experimental measurements and numerical calculations in a coil with a radius of curvature to pipe radius ratio (R_{rm c}/a) equal to 18.2. A new test section and flow apparatus were constructed. The streamwise pressure drop measurements agreed very well with those of previous investigations. Laser-Doppler velocimetry (LDV) measurements of two instantaneous velocity components were obtained along the midplane of the pipe cross-section at a nominally fully developed location in the coil. Thirteen Reynolds numbers were examined in the range 3800 laminar, transitional, and turbulent flow regimes. In the range 5060 flow oscillations (at St = 0.25 and 0.5) in the inner half of the pipe cross-section due to a traveling wave instability. Similar low frequency unsteadiness was not observed near the outer wall. A significant local maximum in the rms velocity was observed near the pipe center for Re > 5060 and is attributed to the velocity perturbation of the traveling wave instability. Still photographs and video images of the flow visualization by means of a dye streak in the range 5060 flow is turbulent beyond this range. The CUTEFLOWS algorithm was modified to solve numerically the finite difference approximation of the Navier-Stokes equations formulated for the toroidal coordinate system. The unsteady three-dimensional calculations were performed for Re = 5480 (De = 1280). The mean characteristics of the flow predicted by the calculations agree very well with the experimental data. The flow perturbation due to the traveling wave agrees qualitatively for all three grid refinements and with the experimental data. The calculated results indicate that energy is transferred to the traveling wave from the mean flow through a complex interaction between the centripetal acceleration in the inner half of

  6. Computer programming for nucleic acid studies. II. Total chemical shifts calculation of all protons of double-stranded helices.

    Science.gov (United States)

    Giessner-Prettre, C; Ribas Prado, F; Pullman, B; Kan, L; Kast, J R; Ts'o, P O

    1981-01-01

    A FORTRAN computer program called SHIFTS is described. Through SHIFTS, one can calculate the NMR chemical shifts of the proton resonances of single and double-stranded nucleic acids of known sequences and of predetermined conformations. The program can handle RNA and DNA for an arbitrary sequence of a set of 4 out of the 6 base types A,U,G,C,I and T. Data files for the geometrical parameters are available for A-, A'-, B-, D- and S-conformations. The positions of all the atoms are calculated using a modified version of the SEQ program [1]. Then, based on this defined geometry three chemical shift effects exerted by the atoms of the neighboring nucleotides on the protons of each monomeric unit are calculated separately: the ring current shielding effect: the local atomic magnetic susceptibility effect (including both diamagnetic and paramagnetic terms); and the polarization or electric field effect. Results of the program are compared with experimental results for a gamma (ApApGpCpUpU) 2 helical duplex and with calculated results on this same helix based on model building of A'-form and B-form and on graphical procedure for evaluating the ring current effects.

  7. Identification of rounded atelectasis in workers exposed to asbestos by contrast helical computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Terra-Filho, M. [Sao Paulo Univ., SP (Brazil). Instituto do Coracao (InCor). Disciplina de Pneumologia]. E-mail: pnemario@incor.usp.br; Kavakama, J. [Sao Paulo Univ., SP (Brazil). Faculdade de Medicina. Disciplina de Radiologia; Bagatin, E. [Universidade Estadual de Campinas, SP (Brazil). Faculdade de Medicina. Area de Medicina Ocupacional; Capelozzi, V.L. [Sao Paulo Univ., SP (Brazil). Faculdade de Medicina. Disciplina de Patologia; Nery, L.E. [Universidade Federal de Sao Paulo (UNIFESP), SP (Brazil). Escola Paulista de Medicina (EPM). Disciplina de Pneumologia; Tavares, R. [Universidade Federal de Sao Paulo (UNIFESP), SP (Brazil). Escola Paulista de Medicina (EPM). Disciplina de Radiologia

    2003-10-01

    Rounded atelectasis (RA) is a benign and unusual form of sub pleural lung collapse that has been described mostly in asbestos-exposed workers. This form of atelectasis manifests as a lung nodule and can be confused with bronchogenic carcinoma upon conventional radiologic examination. The objective of the present study was to evaluate the variation in contrast uptake in computed tomography for the identification of asbestos-related RA in Brazil. Between January 1998 and December 2000, high-resolution computed tomography (HRCT) was performed in 1658 asbestos-exposed workers. The diagnosis was made in nine patients based on a history of prior asbestos exposure, the presence of characteristic (HRCT) findings and lesions unchanged in size over 2 years or more. In three of them the diagnosis was confirmed during surgery. The dynamic contrast enhancement study was modified to evaluate nodules and pulmonary masses. All nine patients with R A received iodide contrast according to weight. The average enhancement after iodide contrast was infused, reported as Hounsfield units (HU), increased from 62.5{+-}9.7 to 125.4{+-}20.7 (P < 0.05), with a mean enhancement of 62.5{+-}19.7 (range 40 to 89) and with a uniform dense opacification. In conclusion, in this study all patients with R A showed contrast enhancement with uniform dense opacification. The main clinical implication of this finding is that this procedure does not permit differentiation between RA and malignant pulmonary neoplasm. (author)

  8. Identification of rounded atelectasis in workers exposed to asbestos by contrast helical computed tomography

    Directory of Open Access Journals (Sweden)

    Terra-Filho M.

    2003-01-01

    Full Text Available Rounded atelectasis (RA is a benign and unusual form of subpleural lung collapse that has been described mostly in asbestos-exposed workers. This form of atelectasis manifests as a lung nodule and can be confused with bronchogenic carcinoma upon conventional radiologic examination. The objective of the present study was to evaluate the variation in contrast uptake in computed tomography for the identification of asbestos-related RA in Brazil. Between January 1998 and December 2000, high-resolution computed tomography (HRCT was performed in 1658 asbestos-exposed workers. The diagnosis was made in nine patients based on a history of prior asbestos exposure, the presence of characteristic (HRCT findings and lesions unchanged in size over 2 years or more. In three of them the diagnosis was confirmed during surgery. The dynamic contrast enhancement study was modified to evaluate nodules and pulmonary masses. All nine patients with RA received iodide contrast according to weight. The average enhancement after iodide contrast was infused, reported as Hounsfield units (HU, increased from 62.5 ± 9.7 to 125.4 ± 20.7 (P < 0.05, with a mean enhancement of 62.5 ± 19.7 (range 40 to 89 and with a uniform dense opacification. In conclusion, in this study all patients with RA showed contrast enhancement with uniform dense opacification. The main clinical implication of this finding is that this procedure does not permit differentiation between RA and malignant pulmonary neoplasm.

  9. MSCTV直接静脉造影诊断静脉受阻性病变的价值%Value of direct multi-slice computed tomography venography in diagnosing venous obstructive disease

    Institute of Scientific and Technical Information of China (English)

    赖伟; 刘建新; 林晓平

    2015-01-01

    目的:探讨多层螺旋CT直接静脉造影(MSCTV)诊断静脉受阻性病变的临床价值。方法收集35例应用直接MSCTV诊断并经临床证实的静脉受阻性病变患者的临床及影像学资料,研究MSCTV成像方法,分析静脉受阻性病变的影像学表现特征。结果本组共35例患者,其中下肢深静脉血栓19例,上肢深静脉血栓2例,深静脉瘤栓3例,单纯性下肢静脉曲张11例。MSCTV深静脉血栓表现为静脉腔内的充盈缺损,管腔中断,侧支循环形成。深静脉瘤栓表现为静脉腔内和/或腔外软组织肿块影,管腔不规则狭窄并充盈缺损。单纯性下肢静脉曲张表现为静脉血管增多、增粗、纡曲。结论静脉受阻性病变具有一定的MSCT征象,MSCTV对诊断静脉受阻性病变具有较大的临床价值。%Objective To explore the clinical value of direct multi-slice computed tomography venography (MSCTV) in diagnosing venous obstructive disease. Methods The clinical and imaging data of 35 cases of venous obstructive disease diagnosed by MSCTV and confirmed in clinic were reviewed. The imaging features of venous ob-structive disease were analyzed. Results There were a total of 35 cases, with 19 cases located in deep venous throm-bosis of lower extremity, 2 cases located in deep venous thrombosis of upper extremity, 3 cases located in deep venous tumor thrombus, and 11 cases located in simple vein varicosis of lower extremity. MSCTV manifestations of deep ve-nous thrombosis included filling defect in vein intraluminal, luminal interrupt, and formation of collateral circulation. MSCTV manifestations of deep venous tumor thrombus showed soft tissue mass in the vein cavity and/or extralumi-nal, irregular filling defect and stenosis in lumen. Simple varicose veins of lower extremity showed increased number of veins, as well as thickening and tortuosity. Conclusion MSCTV manifestations of venous obstructive disease have some specific features

  10. 多层螺旋CT血管成像容积重建技术在Moyamoya病中的诊断价值%The diagnostic value of multi-slice computed tomographic angiography with volume rendering for Moyamoya disease

    Institute of Scientific and Technical Information of China (English)

    林伯法; 奚玉平; 曹国全

    2008-01-01

    Objective To evaluate the diagnostic value of multi-slice thrce-dimensional computed tomographic angiography(MS-CTA) with volume rendering(VR) for Moyamoya disease.Methods MS-CTA of 25 patients with Moyamoya disease verified by DSA were restrospectively analyzed.Source images were got by GE Lightspeed pro scanner.VR was adopted to reconstruct 3D images in all cases.Results Of 25 CT precontrast,13,12 cases showed infarction and hemorrhage respectively,while 11 cases had dialated vessels in thalamus-basal ganglia region on CT.Accuracy of stenosis or occlusion of the bifurcation of ICA, proximal portion of the ACA or MCA was 88.0% (22/25) by MS-CTA.MS-CTA overestimated the degree of stenosis,MS-CTA misdiagnosed 3 cases(12.0%)with stenosis to occlusion.MS-CTA showed fewer small Moyamoya vessels than DSA.MS-CTA only demonstrated 6 cases(25.0%)with collateral vessels.Conclusion CT is still the conventional method for detecting secondary lesions to Moyamoya disease.CT and MS-CTA can accurately diagnose Moyamoya disease.%目的 探讨多层螺旋CT血管造影(MS-CTA)容积重建(VR)技术在Moyamoya病中的诊断价值.方法 对经DSA证实的25例Moyamoya患者的MS-CTA影像资料进行回顾性分析,使用GE Lightspeed pro 16层螺旋CT扫描仪获得原始图像,所有病例均采用VR技术对图像进行三维重建.结果 25例CT平扫患者中,脑梗死13例,脑出血12例,其中11例可见丘脑一基底节区有扩张的血管;MS-CTA VR重建显示Moyamoya病颈内动脉(ICA)末端、大脑中动脉(MCA)或大脑前动脉(ACA)近端闭塞或狭窄的准确率为88.0%(22/25).与DSA相比,MS-CTA VR重建高估动脉狭窄程度,将ICA狭窄误诊为闭塞3例(12.0%);在显示Moyamoya血管数目及分支方面,MS-CTA VR重建显示细小分支数目较少;在显示侧支循环方面,MS-CTA VR重建仅显示6例(25.0%).结论 CT平扫仍是发现Moyamoya病继发病变的常规方法,与MS-CTA VR重建相结合可正确诊断Moyamoya病.

  11. Simultaneous multislice excitation by parallel transmission

    NARCIS (Netherlands)

    Poser, Benedikt A; Anderson, Robert James; Guérin, Bastien; Setsompop, Kawin; Deng, Weiran; Mareyam, Azma; Serano, Peter; Wald, Lawrence L; Stenger, V Andrew

    2014-01-01

    PURPOSE: A technique is described for simultaneous multislice (SMS) excitation using radiofrequency (RF) parallel transmission (pTX). METHODS: Spatially distinct slices are simultaneously excited by applying different RF frequencies on groups of elements of a multichannel transmit array. The localiz

  12. Helical computed tomography of the paranasal sinuses in children: evaluation of sinus inflammatory diseases; Tomografia computadorizada helicoidal dos seios paranasais na crianca: avaliacao das sinusopatias inflamatorias

    Energy Technology Data Exchange (ETDEWEB)

    Dutra, Luiz Dias [Universidade Federal, Rio de Janeiro, RJ (Brazil). Faculdade de Medicina. Dept. de Radiologia; Marchiori, Edson [Universidade Federal Fluminense, Niteroi, RJ (Brazil). Dept. de Radiologia]. E-mail: edmarchiori@zipmail.com.br

    2002-06-01

    We conducted a retrospective analysis of 71 selected pediatric patients, aged 1 to 7 years, which were submitted to helical computed tomography examination of the paranasal sinuses in the period between March, 1997 and April, 1998 due to recurrent acute sinusitis and chronic sinusitis. Clinical and helical computed tomography findings were compared by evaluating the pneumatization of the paranasal sinuses, ostiomeatal complexes, anatomic variants, the status of mucosal surface and lesion extension. The most common CT findings were total or partial opacification of one or more paranasal cavities (92.9%), followed by mucosal thickening (67.6%). In the majority of cases there was association between sinusitis and ostiomeatal obstruction. Anatomic variants were identified from the age of one year. The most common anatomic variant was septonasal deviation (14.1%) that was associated to sinusitis in about 71% of the patients. (author)

  13. The aging process in the sacroiliac joint. Helical computed tomography analysis

    Energy Technology Data Exchange (ETDEWEB)

    Shibata, Yasuaki; Shirai, Yasumasa; Miyamoto, Masabumi [Nippon Medical School, Tokyo (Japan)

    2002-07-01

    The purpose of this study was to compare the frequency of degenerative changes in the sacroiliac joint by age, sex, laterality, body mass index, and childbearing experience, based on computed tomography (CT) images obtained from the lower back of symptom-free subjects in different age groups. These data were used to trace the development of the sacroiliac joint until the occurrence of osteoarthritis with aging. CT transverse and coronal images were examined for the presence of the following degenerative signs: joint space narrowing, sclerosis, osteophytes, cysts, and erosion. The results indicated that joint degeneration begins in the 20s and tends to progress with age. Each form of degeneration was markedly more frequent in the 40s or older, and some type of degeneration was observed in the joints of all subjects aged 50 years or older. In terms of the localization of the joint degeneration, sclerosis was common on the upper and middle anterior of the articular surface of the ilium, osteophytes were common on the anterior surface of the sacrum. Degeneration had progressed further in women than in men in every age group, and tended to progress faster in parous than in nulliparous women, It was presumed that the birth of the first child, rather than subsequent births had the greatest effect on the sacroiliac joint. (author)

  14. Comparison of EBSD patterns simulated by two multislice methods.

    Science.gov (United States)

    Liu, Q B; Cai, C Y; Zhou, G W; Wang, Y G

    2016-10-01

    The extraction of crystallography information from electron backscatter diffraction (EBSD) patterns can be facilitated by diffraction simulations based on the dynamical electron diffraction theory. In this work, the EBSD patterns are successfully simulated by two multislice methods, that is, the real space (RS) method and the revised real space (RRS) method. The calculation results by the two multislice methods are compared and analyzed in detail with respect to different accelerating voltages, Debye-Waller factors and aperture radii. It is found that the RRS method provides a larger view field of the EBSD patterns than that by the RS method under the same calculation conditions. Moreover, the Kikuchi bands of the EBSD patterns obtained by the RRS method have a better match with the experimental patterns than those by the RS method. Especially, the lattice parameters obtained by the RRS method are more accurate than those by the RS method. These results demonstrate that the RRS method is more accurate for simulating the EBSD patterns than the RS method within the accepted computation time.

  15. Assessment of bone segmentation quality of cone-beam CT versus multislice spiral CT: a pilot study.

    NARCIS (Netherlands)

    Loubele, M.; Maes, F.; Schutyser, F.A.C.; Marchal, G.; Jacobs, R.; Suetens, P.

    2006-01-01

    OBJECTIVES: The objective of this study was to quantitatively assess the quality of jawbone models generated from cone beam computed tomography (CBCT) by comparison with similar models obtained from multislice spiral computed tomography (MSCT). MATERIAL AND METHODS: Three case studies were performed

  16. Simulation of folding of a small alpha-helical protein in atomistic detail using worldwide-distributed computing.

    Science.gov (United States)

    Zagrovic, Bojan; Snow, Christopher D; Shirts, Michael R; Pande, Vijay S

    2002-11-08

    By employing thousands of PCs and new worldwide-distributed computing techniques, we have simulated in atomistic detail the folding of a fast-folding 36-residue alpha-helical protein from the villin headpiece. The total simulated time exceeds 300 micros, orders of magnitude more than previous simulations of a molecule of this size. Starting from an extended state, we obtained an ensemble of folded structures, which is on average 1.7A and 1.9A away from the native state in C(alpha) distance-based root-mean-square deviation (dRMS) and C(beta) dRMS sense, respectively. The folding mechanism of villin is most consistent with the hydrophobic collapse view of folding: the molecule collapses non-specifically very quickly ( approximately 20ns), which greatly reduces the size of the conformational space that needs to be explored in search of the native state. The conformational search in the collapsed state appears to be rate-limited by the formation of the aromatic core: in a significant fraction of our simulations, the C-terminal phenylalanine residue packs improperly with the rest of the hydrophobic core. We suggest that the breaking of this interaction may be the rate-determining step in the course of folding. On the basis of our simulations we estimate the folding rate of villin to be approximately 5micros. By analyzing the average features of the folded ensemble obtained by simulation, we see that the mean folded structure is more similar to the native fold than any individual folded structure. This finding highlights the need for simulating ensembles of molecules and averaging the results in an experiment-like fashion if meaningful comparison between simulation and experiment is to be attempted. Moreover, our results demonstrate that (1) the computational methodology exists to simulate the multi-microsecond regime using distributed computing and (2) that potential sets used to describe interatomic interactions may be sufficiently accurate to reach the folded state

  17. [Diagnostic values of bronchoscopy and multi-slice spiral CT for congenital dysplasia of the respiratory system in infants: a comparative study].

    Science.gov (United States)

    Wang, Xing-Lu; Huang, Ying; Li, Qu-Bei; Dai, Ji-Hong

    2013-09-01

    To investigate and compare the diagnostic values of bronchoscopy and multi-slice spiral computed tomography (CT) for congenital dysplasia of the respiratory system in infants. Analysis was performed on the clinical data, bronchoscopic findings and multi-slice spiral CT findings of 319 infants (≤1 years old) who underwent bronchoscopy and/or multi-slice spiral CT and were diagnosed with congenital dysplasia of the respiratory system. A total of 476 cases of congenital dysplasia of the respiratory system were found in the 319 infants, including primary dysplasia of the respiratory system (392 cases) and compressive dysplasia of the respiratory system (84 cases). Of the 392 cases of primary dysplasia of the respiratory system, 225 (57.4%) were diagnosed by bronchoscopy versus 167 (42.6%) by multi-slice spiral CT. There were significant differences in etiological diagnosis between bronchoscopy and multi-slice spiral CT in infants with congenital dysplasia of the respiratory system (Pdysplasia of the respiratory system caused by tracheobronchomalacia were diagnosed by bronchoscopy and all 17 cases of primary dysplasia of the respiratory system caused by lung tissue dysplasia were diagnosed by multi-slice spiral CT. Of the 84 cases of compressive dysplasia of the respiratory system, 74 cases were diagnosed by multi-slice spiral CT and only 10 cases were diagnosed by bronchoscopy. Compared with multi-slice spiral CT, bronchoscopy can detect primary dysplasia of the respiratory system more directly. Bronchoscopy is valuable in the confirmed diagnosis of tracheobronchomalacia. Multi-slice spiral CT has a higher diagnostic value for lung tissue dysplasia than bronchoscopy.

  18. Helical computed tomographic dacryocystography and its role in the diagnosis and management of lacrimal drainage system blocks and medial canthal masses

    Directory of Open Access Journals (Sweden)

    Udhay Priti

    2008-01-01

    Full Text Available Aim: To study the indications, technique and diagnostic utility of helical computed tomographic dacryocystography (CTDCG. Materials and Methods: Retrospective analysis of 13 patients who underwent CTDCG with subsequent surgical intervention, during the period January 2003 to December 2005, was done. Axial plain computed tomography (CT scan was performed, followed by administration of water-soluble contrast in the conjunctival cul de sac or by cannulation of the lacrimal passages. Thin-slice helical CT with two-dimensional (2D and three-dimensional (3D coronal and sagittal reformation was done. Results: Four patients were males and 9 were females. Age range was 5 to 62 years. Seven patients presented with watering and 6 patients with a medial canthal mass. Three patients had history of trauma. CTDCG was performed by instillation technique in 10 patients and by cannulation in 3 patients. CTDCG showed mass lesion displacing the sac in 5 cases, nasolacrimal duct obstruction in 6 cases and mucocele in 2 cases. Based on the findings on CTDCG, 5 patients underwent mass excision, 7 underwent dacryocystorhinostomy and 1 patient underwent primary silicone tube intubation. Conclusion: Helical CTDCG is a safe and useful diagnostic tool for the lacrimal surgeon. Instillation technique is a physiological and convenient method, and cannulation is needed only in cases where adequate visualization is not achieved.

  19. MSCT 检测尘肺患者主肺动脉直径改变的早期诊断意义%The early diagnostic value of multislice spiral computed tomograghy in patients with pneumoconiosis

    Institute of Scientific and Technical Information of China (English)

    范兵; 王世光; 曹国玺; 闫莉

    2016-01-01

    目的:探讨多层螺旋CT( MSCT)检测主肺动脉直径改变用于尘肺患者早期的临床诊断意义。方法选取2013年1月至2015年6月就诊的120例患者纳入研究,分为对照组( A组)、尘肺Ⅰ期组( B组)、尘肺Ⅱ期组( C组)和尘肺Ⅲ期组( D组),每组30例。对4组患者采用高千伏片和MSCT两种方法进行检测,高千伏片进行胸前后位检测,MSCT测定B、C、D组肺动脉直径、右肺动脉直径、左肺动脉直径、主动脉/升主动脉值、主动脉/降主动脉值。并且利用肺功能机测定患者第1秒最大呼气量占预计值的百分比。对两种检测方式的阳性结果进行比较,MSCT测定患者直径指标间进行比较,并且分析直径指标和第1秒最大呼气量占预计值百分比的相关性。结果 MSCT在早期图像诊断方面较高千伏片方法清晰可靠,对尘肺患者阳性检出率在早期诊断率高于高千伏胸片,且各个分期均有所提高,差异有统计学意义( P <0剟.05)。 MSCT所测定的患者的肺动脉直径、左肺动脉直径、右肺动脉直径、主动脉/升主动脉值、主动脉/降主动脉值,且五项指标与EFV1%间呈现负相关关系( r =-0.31,-0.22,-0.27,-0.33,-0.37, P <0.05)。结论以检测肺动脉直径变化为指标,MSCT对于尘肺患者早期诊断具有一定的临床意义。%Objective To investigate the early diagnostic value of multislice spiral computed tomograghy ( MSCT) in patients with pneumoconiosis in different stages.Methods A total of 120 patients with pneumoconiosis who were treated in our hospital from January 2013 to June 2015 were enrolled in the study,these patients were divided into four groups: control group ( group A ) ,group B ( pneumoconiosis in stageⅠ) ,groups C ( pneumoconiosis in stageⅡ) ,group D ( pneumoconiosis in stage Ⅲ,with 30 patients in each group.All the patients underwent

  20. Investigation on the prospects of multi-slice computed tomography enterography in diagnosing small intestine tumor%CT小肠造影在诊断小肠肿瘤中的应用价值

    Institute of Scientific and Technical Information of China (English)

    徐莹; 陈业媛; 舒虹; 肖香佐

    2015-01-01

    目的:探讨多层螺旋CT小肠造影(MSCTE)在小肠肿瘤诊断中的应用价值。方法回顾性分析经手术病理证实的45例小肠肿瘤的MSCTE影像表现,总结其影像学表现特点。结果45例小肠肿瘤中,良性肿瘤9例,其中脂肪瘤6例,影像表现为腔内含脂肪低密度肿块影;腺瘤2例,表现为腔内均质的软组织肿块;回肠系膜淋巴管瘤1例,表现为不规则囊性病灶。常见的恶性肿瘤34例,其中腺癌14例,表现为肠壁局限不规则的环形增厚,中度不均匀强化;间质瘤11例,表现为较大的软组织肿块,以腔外生长为主,密度不均匀,中度或明显强化,常伴有囊变、坏死;淋巴瘤9例,肠壁不规则增厚或形成软组织肿块,累及肠段较长,均匀轻中度强化,常伴有肠系膜、腹膜后淋巴结肿大。少见的恶性肿瘤2例,转移瘤1例,表现为多发肠壁不规则增厚,明显强化,腹壁出现转移性结节;类癌1例,右下腹不规则肿块影。结论 MSCTE在小肠肿瘤诊断与鉴别诊断中有较好的临床应用价值。%Objective To investigate application prospects of Multi-slice computed tomography Enterography(MSCTE) in diag-nosing small intestine tumor (SIT). Methods MSCTE findings were retrospectively analyzed in 45 cases of SIT diagnosed patho-logically after surgery and were summarized in terms of imaging features. Results Of all 45 cases of SIT,9 were benign ones and 6 were lipoma,characterized by low-density mass shadow in intestinal cavity;2 were adenoma,characterized by homogeneous soft tissue mass in intestinal cavity;1 belonged to ileac mesentery lymphangioma,characterized by irregular cyst-like focus;34 were the most common type of malignancies,14 of which were adenocarcinoma,characterized by localized ring-formed thickening of in-testinal wall with moderate heterogeneous enhancement;11 were mesenchymoma,characterized by soft tissue mass relatively big in

  1. Diagnosis of a Bleeding Dieulafoy Lesion on Computed Tomography and Its Subsequent Embolization

    Directory of Open Access Journals (Sweden)

    Robert M Penner

    2004-01-01

    Full Text Available Dieulafoy lesions are a potentially serious cause of gastrointestinal bleeding. Because they may bleed intermittently, and only be endoscopically evident during hemorrhage, their diagnosis can be challenging. This is the first case to be reported in the English literature of a patient with a Dieulafoy lesion diagnosed during computed tomography (CT examination. Reduced acquisition times required for multislice helical CT allow the application of CT angiography in the diagnosis of gastrointestinal bleeding. CT scans are now widely used in the diagnostic algorithm for acute gastrointestinal hemorrhage, and the present case illustrates that with fortuitous timing, they can provide critical information and an opportunity for selected angiography and coil embolization.

  2. Using enveloping distribution sampling to compute the free enthalpy difference between right- and left-handed helices of a β-peptide in solution.

    Science.gov (United States)

    Lin, Zhixiong; Timmerscheidt, Tobias A; van Gunsteren, Wilfred F

    2012-08-14

    Recently, the method of enveloping distribution sampling (EDS) to efficiently obtain free enthalpy differences between different molecular systems from a single simulation has been generalized to compute free enthalpy differences between different conformations of a system [Z. X. Lin, H. Y. Liu, S. Riniker, and W. F. van Gunsteren, J. Chem. Theory Comput. 7, 3884 (2011)]. However, the efficiency of EDS in this case is hampered if the parts of the conformational space relevant to the two end states or conformations are far apart and the conformational diffusion from one state to the other is slow. This leads to slow convergence of the EDS parameter values and free enthalpy differences. In the present work, we apply the EDS methodology to a challenging case, i.e., to calculate the free enthalpy difference between a right-handed 2.7(10∕12)-helix and a left-handed 3(14)-helix of a hexa-β-peptide in solution from a single simulation. No transition between the two helices was detected in a standard EDS parameter update simulation, thus enhanced sampling techniques had to be applied, which included adiabatic decoupling (AD) of solute and solvent motions in combination with increasing the solute temperature, and lowering the shear viscosity of the solvent. AD was found to be unsuitable to enhance the sampling of the solute conformations in the EDS parameter update simulations. Lowering the solvent shear viscosity turned out to be useful during EDS parameter update simulations, i.e., it did speed up the conformational diffusion of the solute, more transitions between the two helices were observed. This came at the cost of more CPU time spent due to the shorter time step needed for simulations with the lower solvent shear viscosity. Using an improved EDS parameter update scheme, parameter convergence was five-fold enhanced. The resulting free enthalpy difference between the two helices calculated from EDS agrees well with the result obtained through direct counting from a

  3. Utility of helical computed tomography in the management of renal colic; Utilidad de la tomografia computarizada helicoidal en el manejo del colico nefritico

    Energy Technology Data Exchange (ETDEWEB)

    Martel, J.; Cruz, R. de la; Rengifo, D. [Fundacion Hospital Alcorcon. Madrid (Spain)

    2000-07-01

    In recent years, noncontrast helical computed tomography has modified the imaging techniques employed in the management of patients who arrive in the emergency service presenting signs of renal colic. Based on the literature and our own experience with 140 patients who complained of pain suggestive of a colic probably due to stone disease, we review the radiological features of this entity and discuss the utility of the technique in confirming the diagnosis, predicting the clinical course and detecting other diseases that present with identical symptomatology. (Author) 20 refs.

  4. Computational model for simulation of sequences of helicity and angular momentum transfer in turbid tissue-like scattering medium (Conference Presentation)

    Science.gov (United States)

    Doronin, Alexander; Meglinski, Igor

    2017-02-01

    Current report considers development of a unified Monte Carlo (MC) -based computational model for simulation of propagation of Laguerre-Gaussian (LG) beams in turbid tissue-like scattering medium. With a primary goal to proof the concept of using complex light for tissue diagnosis we explore propagation of LG beams in comparison with Gaussian beams for both linear and circular polarization. MC simulations of radially and azimuthally polarized LG beams in turbid media have been performed, classic phenomena such as preservation of the orbital angular momentum, optical memory and helicity flip are observed, detailed comparison is presented and discussed.

  5. Comparison of radiation dose and image quality of triple-rule-out computed tomography angiography between conventional helical scanning and a strategy incorporating sequential scanning.

    Science.gov (United States)

    Manheimer, Eric D; Peters, M Robert; Wolff, Steven D; Qureshi, Mehreen A; Atluri, Prashanth; Pearson, Gregory D N; Einstein, Andrew J

    2011-04-01

    Triple-rule-out computed tomographic angiography (TRO CTA), performed to evaluate the coronary arteries, pulmonary arteries, and thoracic aorta, has been associated with high radiation exposure. The use of sequential scanning for coronary computed tomographic angiography reduces the radiation dose. The application of sequential scanning to TRO CTA is much less well defined. We analyzed the radiation dose and image quality from TRO CTA performed at a single outpatient center, comparing the scans from a period during which helical scanning with electrocardiographically controlled tube current modulation was used for all patients (n = 35) and after adoption of a strategy incorporating sequential scanning whenever appropriate (n = 35). Sequential scanning was able to be used for 86% of the cases. The sequential-if-appropriate strategy, compared to the helical-only strategy, was associated with a 61.6% dose decrease (mean dose-length product of 439 mGy × cm vs 1,144 mGy × cm and mean effective dose of 7.5 mSv vs 19.4 mSv, respectively, p TRO CTA with a diagnostic strategy of sequential scanning, as appropriate, can offer a marked reduction in the radiation dose while maintaining the image quality. Copyright © 2011 Elsevier Inc. All rights reserved.

  6. Helical filaments

    Energy Technology Data Exchange (ETDEWEB)

    Barbieri, Nicholas; Lim, Khan; Durand, Magali; Baudelet, Matthieu; Richardson, Martin [Townes Laser Institute, CREOL—The College of Optics and Photonics, University of Central Florida, Orlando, Florida 32816 (United States); Hosseinimakarem, Zahra; Johnson, Eric [Micro-Photonics Laboratory – Center for Optical Material Science, Clemson, Anderson, South Carolina 29634 (United States)

    2014-06-30

    The shaping of laser-induced filamenting plasma channels into helical structures by guiding the process with a non-diffracting beam is demonstrated. This was achieved using a Bessel beam superposition to control the phase of an ultrafast laser beam possessing intensities sufficient to induce Kerr effect driven non-linear self-focusing. Several experimental methods were used to characterize the resulting beams and confirm the observed structures are laser air filaments.

  7. Characteristics and diagnosis of multi-slice computed tomography examination of portal vein diseases%门静脉病变的多排螺旋CT检查特征与诊断

    Institute of Scientific and Technical Information of China (English)

    任小军; 潘高争; 王霞; 杨如武

    2015-01-01

    恶性肿瘤引起胆管梗阻17例,肝硬化门静脉海绵样变伴肝内胆管扩张(门静脉高压性胆管病)2例.结论 门静脉病变多排螺旋CT检查主要表现为门静脉狭窄、闭塞或扩张、积气,其继发病变表现为门-腔静脉侧支循环形成及门静脉海绵样变、肠缺血以及门静脉高压性胆病;其原发病变多样,以肝硬化和恶性肿瘤为主.多排螺旋CT检查可清楚显示门静脉病变,对其原发病变与继发病变可进行准确诊断.%Objective To summarize the characteristics of multi-slice computed tomography (MSCT) of portal vein diseases and investigate the CT diagnosis of its primary and secondary diseases.Methods The imaging data of 62 patients from Xi'an Xidian Group Hospital,28 patients from Nuclear Industry 215 Hospital of Shanxi Province and 16 patients from Xi'an Gaoxin Hospital with portal vein diseases from January 2012 to March 2015 were retrospectively analyzed.The CT findings,primary and secondary diseases of portal vein lesions were recorded through plain scan and enhanced scan of MSCT.Results Changes in the width of portal vein:among 106 patients,dilation of main portal vein was detected in 45 cases,stenosis of stem or branches of portal vein in 39 cases,portal vein obstruction in 49 cases (21 patients accompanied with enlargement in stem of portal vein and 6 patients with normal width).The diameters of dilated portal vein were 1.4-2.2 cm with a mean diameter of 1.8 cm.The diameters of portal vein with stenosis and occlusion caused by carcinomas were 1.8-4.0 cm with a mean diameter of 2.3cm.Portal vein fistula and pneumatosis:hepatic artery-portal vein fistulas were detected in 12 patients,posterior right branches of portal vein-inferior vena cava fistulas in 2 patients,inferior vena cavaportal vein fistulas and portal-hepatic vein fistulas in 2 patients,pneumatosis in 2 patients.Lesions of portal vein occlusions:occlusions located at main portal veins were detected in 4 cases

  8. Image quality and feasibility of an ultralow-dose high-pitch helical triple-rule-out computed tomography angiography acquired in the caudocranial direction.

    Science.gov (United States)

    Kligerman, Seth J; White, Charles S

    2014-01-01

    The aim of this study was to assess the feasibility and image quality of a low-dose triple-rule-out (TRO) computed tomography (CT) angiogram on a second-generation dual-source CT scanner using a high-pitch helical acquisition. Ten men (mean age 56.3 y, average body mass index 24.2) underwent TRO CT angiography using a high-pitch helical acquisition. Patients were imaged from the lung bases to the thoracic inlet in a caudocranial direction. A biphasic injection was administered at 6 mL/s. Study parameters including kVp, mAs, CT dose index volume, dose-length product, and effective dose were calculated. Image quality was independently assessed by 2 cardiothoracic radiologists using the following scale: 1-nondiagnostic; 2-moderately limited diagnostic ability; 3-mild limitation but diagnostic; 4-ideal. For each patient up to 23 structures were evaluated: 17 coronary segments, 3 pulmonary artery levels, 2 aortic sections, and the lung parenchyma. The unpaired t test and the Fisher exact test were used for comparison between patients scored at 80 and 100 kV. The average CT dose index volume, dose-length product, and effective dose for the TRO scans was 2.65, 81.9, and 1.39 mSv, respectively. Readers 1 and 2 scored 171/203 (83%) and 173/203 (84%) of the evaluated regions as ideal and 26/203 (12.8%) and 24/203 (11.8%) as being mildly limited, respectively. Each reader graded 6/203 (3.9%) as being moderately limited. No areas were nondiagnostic. Patients scanned at 80 kV had a significantly higher number of limited segments for readers 1 (P=0.0012) and 2 (P=0.0027). Low-dose, high-image quality TRO scans can be effectively performed using a high-pitch helical acquisition.

  9. The relationship of abdominal fat mass assessed by helical or conventional computed tomography to serum leptin concentration.

    Science.gov (United States)

    Kobayashi, Junji; Sasaki, Takeyoshi; Watanabe, Mitsuyo

    2004-01-01

    In the present study, we focused on the relationship of intra-abdominal visceral fat (VF) or subcutaneous fat (SF) mass to serum leptin levels, and also on the relationship of leptin to serum lipid and lipoprotein concentration. Subjects with obesity (26 men, 26 women) were recruited for this study. We obtained helical CT scans with a tube current of 150 mA, voltage of 120 kV and 2:1 pitch (table speed in relation to slice thickness), starting at the upper edge of the liver and continuing to the pelvis. The intra-abdominal visceral fat (VF) volume was measured by drawing a line within the muscle wall surrounding the abdominal cavity. The abdominal SF volume was calculated by subtracting the VF volume from the total abdominal fat volume. By comparison, the abdominal VF and SF areas were determined at the umbilical level by the established slice-by-slice CT scanning technique. We found: 1) abdominal SF mass, either as volume or area, was a more important determinant of serum leptin than was VF mass; 2) among TC, TG, HDL-C and LDL-C, only TG had a positive correlation to serum leptin levels in men, whereas in women no lipid parameters had any relationship with leptin; and 3) VF mass had a positive correlation to serum TC and TG in men, whereas SF did not. The present study provides considerable evidence on the relationship between abdominal fat mass and serum leptin, and shows that the relationships between serum leptin and serum lipids and lipoproteins are not straightforward. We also suggest that fat area measured by conventional CT is a better indicator than its corresponding volume assessed by helical CT, based on the present results showing its closer association to serum lipids.

  10. The role of multislice spiral CT in clinical cardiology

    Energy Technology Data Exchange (ETDEWEB)

    Haberl, R.; Boehme, E.; Richartz, B.; Czernik, A.; Buck, J.; Steinbigler, P. [Medical Hospital I and Department of Radiology, Klinik Muenchen-Pasing, Munich (Germany)

    2004-05-01

    Multislice spiral CT provides diagnostic-quality images of native coronary arteries and bypasses. Indications include prognosis in asymptomatic individuals, detection of significant coronary stenosis, and follow-up after interventions or surgery.

  11. Multislice CT angiography of interrupted aortic arch

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Dong Hyun; Goo, Hyun Woo [Asan Medical Center, Department of Radiology and Research Institute of Radiology, Seoul (Korea); Seo, Dong-Man; Yun, Tae-Jin; Park, Jeong-Jun [Asan Medical Center, University of Ulsan College of Medicine, Department of Paediatric Cardiac Surgery, Seoul (Korea); Park, In-Sook; Ko, Jae Kon; Kim, Young Hwee [Asan Medical Center, University of Ulsan College of Medicine, Department of Paediatric Cardiology, Seoul (Korea)

    2008-01-15

    Interrupted aortic arch (IAA) is defined as complete luminal and anatomic discontinuity between the ascending and descending aorta. Because almost all patients with IAA become critically ill during the neonatal period, they should undergo urgent corrective surgery. This clinical urgency necessitates a fast and accurate noninvasive diagnostic method. Although echocardiography remains the primary imaging tool for this purpose, it is not always sufficient for planning surgical correction of IAA, principally due to a limited acoustic window and the inexperience of imagers. In this context, multislice CT angiography is regarded as an appropriate imaging technique complementary to echocardiography because it is fast, accurate, and objective for the diagnosis of IAA. In this article we describe what cardiac radiologists should know about IAA in their clinical practice, including clinicopathological features, CT features with contemporary surgical methods and postoperative complications, and differentiation from coarctation of the aorta and aortic arch atresia. (orig.)

  12. Pulmonary embolism findings on chest radiographs and multislice spiral CT

    Energy Technology Data Exchange (ETDEWEB)

    Coche, Emmanuel; Goncette, Louis [Department of Radiology, Cliniques Universitaires Saint-Luc, Universite Catholique de Louvain, Avenue Hippocrate 10, 1200, Brussels (Belgium); Verschuren, Franck [Department of Intensive Care and Emergency Medicine, Cliniques Universitaires Saint-Luc, Universite Catholique de Louvain, Avenue Hippocrate 10, 1200, Brussels (Belgium); Hainaut, Philippe [Department of Internal Medicine, Cliniques Universitaires Saint-Luc, Universite Catholique de Louvain, Avenue Hippocrate 10, 1200, Brussels (Belgium)

    2004-07-01

    Multislice spiral CT is becoming an increasingly important tool for diagnosing pulmonary embolism. However, in many instances, a chest radiograph is usually performed as a first-line examination. Many parenchymal, vascular, and other ancillary findings may be observed on both imaging modalities with a highly detailed depiction of abnormalities on multislice CT. A comprehensive review of chest radiograph findings is presented with side-by-side correlations of CT images reformatted mainly in the frontal plane. (orig.)

  13. Pulmonary embolism findings on chest radiographs and multislice spiral CT.

    Science.gov (United States)

    Coche, Emmanuel; Verschuren, Franck; Hainaut, Philippe; Goncette, Louis

    2004-07-01

    Multislice spiral CT is becoming an increasingly important tool for diagnosing pulmonary embolism. However, in many instances, a chest radiograph is usually performed as a first-line examination. Many parenchymal, vascular, and other ancillary findings may be observed on both imaging modalities with a highly detailed depiction of abnormalities on multislice CT. A comprehensive review of chest radiograph findings is presented with side-by-side correlations of CT images reformatted mainly in the frontal plane.

  14. Common breakdown maintenance of GE light speed 16-slice Helical CT%GE light speed 16排螺旋CT常见故障的维修和体会

    Institute of Scientific and Technical Information of China (English)

    苏根元; 王萍萍; 于小晶

    2011-01-01

    Recently,with the extensive application of multi-slice Helical CT,all sorts of failure have been encountered in practice.On the basis of mastering basic principal and structure of multi-slice Helical CT,and relevant knowledge of computer,many breakdowns may be quickly resolved.It has greatly improved the efficiency of equipments and ensured daily operations.This paper briefly describes common breakdown of GE light speed 16-slice Helical CT in our hospital,and summarizes diagnostic analysis,solution and experience.It can serve as reference for concerned personnel.%多排螺旋CT目前已广泛应用于临床,使用过程中会遇到各种各样故障,在熟练掌握多排螺旋CT的基本原理,工作结构,及相关计算机知识的基础上,可以对多排螺旋CT机很多常见故障进行快速及时修复,大大提高了设备使用率,保证临床工作的顺利进行。本文简要阐述了我院GE light speed 16排螺旋CT在使用过程中常见的故障现象、诊断分析、解决方法和体会。为相关专业技术人员提供一定的参考和借鉴。

  15. Multi-slice Spiral Computed Tomography Manifestations of Brain and Cerebral Hemodynamics in Chronic Mountain Sickness%慢性高原病脑部MSCT表现与血流动力学研究

    Institute of Scientific and Technical Information of China (English)

    王铎尧; 鲍海华; 赵希鹏; 李文方

    2011-01-01

    significantly highcr in CMS group than that in normal group (t=4. 551, P<0. 01 and t= 2. 898,P<0. 01 , respectively) . In CMS group , the CT value of superior sagittal sinus and bilateral middle cerebral artery with hemoglobin level (r=0. 758 and r=0. 740 , both P<0. 01). (2) The changes of CBF were obviously in grey matter than in white matter. In grey matter,CBF reduced more in CMS group than in normal group(P<0. 01). TTP in grey matter prolonged obviously in CMS group (P<0. 05 ). MTT in grey matter and white matter both prolonged obviously in CMS group (P<0. 01 ). Conclusion Multi-slice spiral CT is a valuable tool to study the state of the whole brain and the cercbral hemodvnamics in CMS patients.

  16. Predicting response to neoadjuvant chemotherapy in primary breast cancer using volumetric helical perfusion computed tomography: a preliminary study

    Energy Technology Data Exchange (ETDEWEB)

    Li, Sonia P.; Makris, Andreas [Academic Oncology Unit, Mount Vernon Cancer Centre, Middlesex (United Kingdom); Gogbashian, Andrew; Simcock, Ian C.; Stirling, J.J. [Paul Strickland Scanner Centre, Mount Vernon Cancer Centre, Middlesex (United Kingdom); Goh, Vicky [Paul Strickland Scanner Centre, Mount Vernon Cancer Centre, Middlesex (United Kingdom); Lambeth Wing, St Thomas' Hospital, Division of Imaging Sciences, Kings College London, London (United Kingdom)

    2012-09-15

    To investigate whether CT-derived vascular parameters in primary breast cancer predict complete pathological response (pCR) to neoadjuvant chemotherapy (NAC). Twenty prospective patients with primary breast cancer due for NAC underwent volumetric helical perfusion CT to derive whole tumour regional blood flow (BF), blood volume (BV) and flow extraction product (FE) by deconvolution analysis. A pCR was achieved if no residual invasive cancer was detectable on pathological examination. Relationships between baseline BF, BV, FE, tumour size and volume, and pCR were examined using the Mann-Whitney U test. Receiver operating characteristic (ROC) curve analysis was performed to assess the parameter best able to predict response. Intra- and inter-observer variability was assessed using Bland-Altman statistics. Seventeen out of 20 patients completed NAC with four achieving a pCR. Baseline BF and FE were higher in patients who achieved a pCR compared with those who did not (P = 0.032); tumour size and volume were not significantly different (P > 0.05). ROC analysis revealed that BF and FE were able to identify responders effectively (AUC = 0.87; P = 0.03). There was good intra- and inter-observer agreement. Primary breast cancers which exhibited higher levels of perfusion before treatment were more likely to achieve a pCR to NAC. (orig.)

  17. Nonlinear helical MHD instability

    Energy Technology Data Exchange (ETDEWEB)

    Zueva, N.M.; Solov' ev, L.S.

    1977-07-01

    An examination is made of the boundary problem on the development of MHD instability in a toroidal plasma. Two types of local helical instability are noted - Alfven and thermal, and the corresponding criteria of instability are cited. An evaluation is made of the maximum attainable kinetic energy, limited by the degree to which the law of conservation is fulfilled. An examination is made of a precise solution to a kinematic problem on the helical evolution of a cylindrical magnetic configuration at a given velocity distribution in a plasma. A numerical computation of the development of MHD instability in a plasma cylinder by a computerized solution of MHD equations is made where the process's helical symmetry is conserved. The development of instability is of a resonance nature. The instability involves the entire cross section of the plasma and leads to an inside-out reversal of the magnetic surfaces when there is a maximum unstable equilibrium configuration in the nonlinear stage. The examined instability in the tore is apparently stabilized by a magnetic hole when certain limitations are placed on the distribution of flows in the plasma. 29 references, 8 figures.

  18. Design of a linear detector array unit for high energy x-ray helical computed tomography and linear scanner

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jeong Tae; Park, Jong Hwan; Kim, Gi Yoon [Dept. of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon (Korea, Republic of); Kim, Dong Geun [Medical Imaging Department, ASTEL Inc., Seongnam (Korea, Republic of); Park, Shin Woong; Yi, Yun [Dept. of Electronics and Information Eng, Korea University, Seoul (Korea, Republic of); Kim, Hyun Duk [Research Center, Luvantix ADM Co., Ltd., Daejeon (Korea, Republic of)

    2016-11-15

    A linear detector array unit (LdAu) was proposed and designed for the high energy X-ray 2-d and 3-d imaging systems for industrial non-destructive test. Specially for 3-d imaging, a helical CT with a 15 MeV linear accelerator and a curved detector is proposed. the arc-shape detector can be formed by many LdAus all of which are arranged to face the focal spot when the source-to-detector distance is fixed depending on the application. An LdAu is composed of 10 modules and each module has 48 channels of CdWO{sub 4} (CWO) blocks and Si PIn photodiodes with 0.4 mm pitch. this modular design was made for easy manufacturing and maintenance. through the Monte carlo simulation, the CWO detector thickness of 17 mm was optimally determined. the silicon PIn photodiodes were designed as 48 channel arrays and fabricated with NTD (neutron transmutation doping) wafers of high resistivity and showed excellent leakage current properties below 1 nA at 10 V reverse bias. to minimize the low-voltage breakdown, the edges of the active layer and the guard ring were designed as a curved shape. the data acquisition system was also designed and fabricated as three independent functional boards; a sensor board, a capture board and a communication board to a Pc. this paper describes the design of the detectors (CWO blocks and Si PIn photodiodes) and the 3-board data acquisition system with their simulation results.

  19. MULTEM: A new multislice program to perform accurate and fast electron diffraction and imaging simulations using Graphics Processing Units with CUDA.

    Science.gov (United States)

    Lobato, I; Van Dyck, D

    2015-09-01

    The main features and the GPU implementation of the MULTEM program are presented and described. This new program performs accurate and fast multislice simulations by including higher order expansion of the multislice solution of the high energy Schrödinger equation, the correct subslicing of the three-dimensional potential and top-bottom surfaces. The program implements different kinds of simulation for CTEM, STEM, ED, PED, CBED, ADF-TEM and ABF-HC with proper treatment of the spatial and temporal incoherences. The multislice approach described here treats the specimen as amorphous material which allows a straightforward implementation of the frozen phonon approximation. The generalized transmission function for each slice is calculated when is needed and then discarded. This allows us to perform large simulations that can include millions of atoms and keep the computer memory requirements to a reasonable level.

  20. Small intestinal lipomas:Diagnostic value of multi-slice CT enterography

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    AIM:To analyze the clinical and imaging features of the small intestinal lipomas and to evaluate the diagnostic value of multi-slice computed tomography(CT) enterography.METHODS:Fourteen cases(one had two intestinal lesions) of surgically confirmed lipomas of the small intestine were retrospectively analyzed.The location,size,clinical and radiological aspects were discussed.RESULTS:Twelve patients presented with abdominal pain,of whom three complained of paroxysmal colic.Melena or bloody stools was mentione...

  1. Usefulness of 3D-CT angiography using multislice CT for diagnosing cardiovascular anomalies in infants

    Energy Technology Data Exchange (ETDEWEB)

    Kani, Hiroyuki; Matsuki, Mitsuru; Masuda, Kiyohiro; Narabayashi, Isamu; Katayama, Hiroshi; Mori, Yasuhiko; Tamai, Hiroshi [Osaka Medical Coll., Takatsuki (Japan)

    2003-05-01

    We compared three-dimensional computed tomographic angiography using multislice CT (3D-CTA) with echocardiography and angiography in terms of usefulness in the diagnosis of 13 infants with cardiovascular anomalies. 3D-CTA clearly depicted stenoses of the pulmonary artery and vein, and coarctation of the aorta in some cases, which could not be revealed by echocardiography and angiography. Moreover, it provided objectively more information on vascular morphologic characteristics and 3D anatomic relations than echocardiography and angiography. 3D-CTA is a noninvasive and convenient diagnostic technique for cardiovascular anomalies in infants. (author)

  2. 多层螺旋 CT 口服小肠造影与胶囊内镜对不明原因腹痛患者诊断价值的对比研究%Comparison of diagnostic value of multi-slice computer tomography enterography versus capsule endoscopy for unexplained abdominal pain

    Institute of Scientific and Technical Information of China (English)

    梁晓燕; 伦伟健; 黄鹤; 贾柳萍

    2016-01-01

    Objective To compare and evaluate the diagnositic value of multi-slice computer tomography enterography (MSCTE)versus capsule endoscopy for patients with unexplained abdominal pain.Methods twenty-nine cases of unknown abdominal pain were collected.8 cases of 29 cases received MSCTE examination,24 cases received the capsule endoscopy and 3 cases received both of the examinations.Results The detection rate for lesions was 62.5% by MSCTE and 75.0% by capsule endoscopy.There was no statistical difference between the two methods(P >0.05).The detection rate in cases undergoing both examinations was 1 00%. Conclusions MSCTE and capsule endoscopy have high diagnostic value in patients with unexplained abdominal pain.The detection rate can be increased if the two methods are combined to conduct examination.%目的:对比多层螺旋 CT 口服小肠造影(MSCTE)与胶囊内镜对不明原因腹痛患者的诊断价值。方法收集29例不明原因腹痛患者,其中 MSCTE 检查8例,胶囊内镜检查24例,同时接受两种方法检查3例。结果 MSCTE 病变检出率为62.5%,胶囊内镜为75.0%,两者差别无统计学意义(P >0.05),联合两者病变检出率为100%。结论 MSCTE 与胶囊内镜检查对不明原因腹痛患者具有较高的诊断价值,二者联合诊断意义更高。

  3. The study of water shell structure of double-helical B-DNA fragments using parallel computing

    OpenAIRE

    Teplukhin, Alexander V.; Lemesheva, Yulia S.

    2014-01-01

    Comment: Translated from Russian. See original text published in: ISBN 5-93972-188-5, "Computers and Supercomputers in Biology" / Lakhno V.D., Ustinin M.N. Eds., Moskva-Izhevsk: IKI, 2002, Part 1, Chapter 8, pp. 234-240

  4. The Study of Relationship between Inferior Phrenic Artery Originated from Abdominal Aorta and Celiac Trunk by Using Multi-Slice Helical CT%起源于腹主动脉的膈下动脉与腹腔干关系的多层螺旋CT研究

    Institute of Scientific and Technical Information of China (English)

    宫凤玲; 于鹏; 张惠英; 李盖; 赵鹤亮; 孙凤涛

    2011-01-01

    Purpose To explore whether there are some rules in the relationship between inferior phrenic artery (IPA) originated from the abdominal aorta and the celiac trunk. Materials and Methods The origin of IPA in 200 patients (174 with abdomen scan and 26 with chest-abdomen scan) who underwent two-phase enhanced CT scan at Philips 256-slice helical CT were respectively observed. The relationship of the orifice position between IPA originated from the abdominal aorta and the celiac trunk was analysed. Results RIPA was shown in 200 cases with total 201 branches. LIPA was shown in 198 cases with total 203 branches. 2 cases of LIPA were not shown. Bilateral IPA originated from a common stem was seen in 48 of 200 cases (24%). RIPA originated from the celiac trunk in 70/201 cases(34.8%) , from the aorta in 82/201 cases(40.8%), from the right renal artery in 37/201cases (18.4%), from the right accessory renal artery in 4/201cases (2.0%) and from the lefi gastric artery in 8/201 cases (4%). LIPA originated from the celiac trunk in 113/203 cases (55.7%), from the aorta in 77/203 cases (37.g%), from the left gastric artery in 11/203 cases(5.4%) and from the spleen artery in 2/203 cases (1.0%). There are some rules in the relationship between the origin of IPA originated from the abdominal aorta (135cases) and the celiac trunk: ① 98.3% of RIPA located in the 9-12 o'clock position relative to the wall of the aorta. LIPA and IPA which originated from a common stem located in the 12-3 o'clock position relative to the wall of aorta ; ② 80.0% of IPA had orifice located 10mm upper or lower of the orifice of the celiac trunk and the remaining located 10mm lower than the orifice of the celiac trunk.③ 63.8% of RIPA had the orifice located under the orifice of the celiac trunk. 43.4% of LIPA and 54.2% of IPA which originated from a common stem located upper than the orifice of the celiac trunk. ④ 86.8% of IPA had the orifice located under the orifice

  5. Experimental Study of Multi-slice Spiral CT Perfusion Imaging in VX2 Soft-tissue Tumor of Rabbits

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jingfeng; WANG Renfa; WANG Min; LI Yonggang; YANG Haitao

    2006-01-01

    An experimental animal model of malignant soft-tissue tumor was established to investigate the applied value of multi-slice spiral CT perfusion imaging preliminarily. Ten New Zealand white rabbits which were implanted with VX2 tumor in either proximal thigh were subjected to CT plain scan and perfusion scan two weeks later respectively, then the original perfusion images were transmitted to AW4.0 Workstation. The functional maps and perfusion parameters including blood flow (BF), blood volume (BV), mean transit time (MTT) and permeability surface (PS) were computed and analyzed. All the values of BF, BV and PS in VX2 soft-tissue tumors were obviously higher while the MTT-values were lower than those in the normal muscular tissues significantly. It was suggested that multi-slice spiral CT perfusion imaging is an accurate, convenient and relatively safe functional imaging technique, and can give a quantitative assessment to angiogenesis and blood perfusion of soft-tissue tumors.

  6. Currents for Arbitrary Helicity

    CERN Document Server

    Dragon, Norbert

    2016-01-01

    Using Mackey's classification of unitary representations of the Poincar\\'e group on massles states of arbitrary helicity we disprove the claim that states with helicity |h|>=1 cannot couple to a conserved current by constructing such a current.

  7. MULTEM: A new multislice program to perform accurate and fast electron diffraction and imaging simulations using Graphics Processing Units with CUDA

    Energy Technology Data Exchange (ETDEWEB)

    Lobato, I., E-mail: Ivan.Lobato@uantwerpen.be; Van Dyck, D.

    2015-09-15

    The main features and the GPU implementation of the MULTEM program are presented and described. This new program performs accurate and fast multislice simulations by including higher order expansion of the multislice solution of the high energy Schrödinger equation, the correct subslicing of the three-dimensional potential and top-bottom surfaces. The program implements different kinds of simulation for CTEM, STEM, ED, PED, CBED, ADF-TEM and ABF-HC with proper treatment of the spatial and temporal incoherences. The multislice approach described here treats the specimen as amorphous material which allows a straightforward implementation of the frozen phonon approximation. The generalized transmission function for each slice is calculated when is needed and then discarded. This allows us to perform large simulations that can include millions of atoms and keep the computer memory requirements to a reasonable level. - Highlights: • The main features and the GPU implementation of the open source MULTEM program are described. • Accurate and fast multislice simulations for TEM simulations. • Three dimensional frozen phonon calculations at no extra computational cost.

  8. Comparison between ultrasound and noncontrast helical computed tomography for identification of acute ureterolithiasis in a teaching hospital setting

    Directory of Open Access Journals (Sweden)

    Luís Ronan Marquez Ferreira de Souza

    2007-03-01

    Full Text Available CONTEXT AND OBJECTIVE: Recent studies have shown noncontrast computed tomography (NCT to be more effective than ultrasound (US for imaging acute ureterolithiasis. However, to our knowledge, there are few studies directly comparing these techniques in an emergency teaching hospital setting. The objectives of this study were to compare the diagnostic accuracy of US and NCT performed by senior radiology residents for diagnosing acute ureterolithiasis; and to assess interobserver agreement on tomography interpretations by residents and experienced abdominal radiologists. DESIGN AND SETTING: Prospective study of 52 consecutive patients, who underwent both US and NCT within an interval of eight hours, at Hospital São Paulo. METHODS: US scans were performed by senior residents and read by experienced radiologists. NCT scan images were read by senior residents, and subsequently by three abdominal radiologists. The interobserver variability was assessed using the kappa statistic. RESULTS: Ureteral calculi were found in 40 out of 52 patients (77%. US presented sensitivity of 22% and specificity of 100%. When collecting system dilatation was associated, US demonstrated 73% sensitivity, 82% specificity. The interobserver agreement in NCT analysis was very high with regard to identification of calculi, collecting system dilatation and stranding of perinephric fat. CONCLUSIONS: US has limited value for identifying ureteral calculi in comparison with NCT, even when collecting system dilatation is present. Residents and abdominal radiologists demonstrated excellent agreement rates for ureteral calculi, identification of collecting system dilatation and stranding of perinephric fat on NCT.

  9. Development of Multi-slice Analytical Tool to Support BIM-based Design Process

    Science.gov (United States)

    Atmodiwirjo, P.; Johanes, M.; Yatmo, Y. A.

    2017-03-01

    This paper describes the on-going development of computational tool to analyse architecture and interior space based on multi-slice representation approach that is integrated with Building Information Modelling (BIM). Architecture and interior space is experienced as a dynamic entity, which have the spatial properties that might be variable from one part of space to another, therefore the representation of space through standard architectural drawings is sometimes not sufficient. The representation of space as a series of slices with certain properties in each slice becomes important, so that the different characteristics in each part of space could inform the design process. The analytical tool is developed for use as a stand-alone application that utilises the data exported from generic BIM modelling tool. The tool would be useful to assist design development process that applies BIM, particularly for the design of architecture and interior spaces that are experienced as continuous spaces. The tool allows the identification of how the spatial properties change dynamically throughout the space and allows the prediction of the potential design problems. Integrating the multi-slice analytical tool in BIM-based design process thereby could assist the architects to generate better design and to avoid unnecessary costs that are often caused by failure to identify problems during design development stages.

  10. Reformatted visceral protocol helical computed tomographic scanning allows conventional radiographs of the thoracic and lumbar spine to be eliminated in the evaluation of blunt trauma patients.

    Science.gov (United States)

    Sheridan, Robert; Peralta, Ruben; Rhea, James; Ptak, Thomas; Novelline, Robert

    2003-10-01

    Patients suffering high-energy injuries are at risk for occult thoracic and lumbar spine fractures, and the standard of care includes radiographic spine screening. Most such patients require computed tomographic (CT) scanning to screen for chest and/or abdominal visceral injury. Helical CT (HCT) scanning represents a major technologic change that allows data to be reformatted after the patient has left the radiology suite. We explored the possibility of using reformatted visceral protocol HCT scanning to replace radiographs of the thoracic and lumbar spine in the evaluation of seriously injured patients. A prospective evaluation of consecutive patients with thoracic and lumbar spine fractures admitted over a 12-month period to an urban Level I trauma center was completed. The ability of conventional radiography and reformatted HCT scanning to detect spine fractures was compared. Of 1,915 trauma patients admitted, 78 (4.1%), with an average Injury Severity Score of 21.3 +/- 1.2, sustained one or more thoracic (n = 35 patients) or lumbar (n = 43 patients) spine fractures. The sensitivity of reformatted HCT scanning as a screening test for spine fractures was 97% for thoracic and 95% for lumbar spine fractures, compared with a sensitivity of 62% for thoracic and 86% for lumbar conventional radiographs. Data obtained from HCT scanning performed to evaluate seriously injured multiple trauma patients for thoracic and abdominal visceral injury can be reformatted to screen for thoracic and lumbar spine fractures, providing accurate screening while eliminating the time, expense, and radiation exposure associated with conventional film radiography.

  11. Evaluation of Medial Acetabular Wall Bone Stock in Patients with Developmental Dysplasia of the Hip Using a Helical Computed Tomography Multiplanar Reconstruction Technique

    Energy Technology Data Exchange (ETDEWEB)

    Rui Yu Liu; Kun Zheng Wang; Chun Sheng Wang; Xiao Qian Dang; Zhi Qin Tong (Second Hospital Affiliated to the Medical College of Xi' an Jiaotong Univ., Xi' an Shaanxi (China))

    2009-08-15

    Background: The technique of medialization has been used to reconstruct acetabula at the level of true acetabula in total hip arthroplasty (THA) in patients with developmental dysplasia of the hip (DDH). Appreciation of the bone stock in the medial acetabular wall is significant for making an optimal acetabular reconstruction plan and avoiding complications. Purpose: To evaluate the bone stock of the medial acetabular wall and its relation to the degree of subluxation in patients with DDH using computed tomography (CT). Material and Methods: Helical CT scans of 27 hips were obtained from 21 patients with osteoarthritis secondary to DDH who were scheduled for total hip arthroplasty. Eleven hips belonged to Crowe class I, while 16 hips belonged to Crowe class II/III. The raw CT data were reprocessed in various planes by scrolling multiplanar reformation (MPR). Acetabular opening, depth, and medial bone stock, as indicated by the minimum thickness of the medial acetabular wall, were measured in the transverse reformed MPR plane. Results: The minimum thicknesses of the medial acetabular wall in Crowe-I and Crowe-II/III hips were 3.8+-2.1 mm and 7.1+-3.1 mm, respectively, with statistically significant differences between the groups (P<0.05). Furthermore, the bone stock in the medial acetabular wall correlated with the degree of subluxation (R=0.69) and the acetabular depth (R= ;- ;0.71). Conclusion: There was significantly more bone stock in the medial acetabular wall in patients with higher-degree subluxation than there was in the less-severe class. This difference should be taken into consideration when reconstructing acetabula in THA in patients with DDH using the technique of medialization

  12. 多排螺旋CT(MSCT)动态增强对孤立性肺结节血流模式的评价%Evaluation of Blood Flow Patterns of Solitary Pulmonary Nodules with Dynamic Multi-slice Spiral Computed Tomography

    Institute of Scientific and Technical Information of China (English)

    LI Shenjiang; 李慎江; XIAO Xiangsheng; 肖湘生; LI Huimin; 李惠民; LIU Shiyuan; LI Chengzhou; ZHANG Chenshi; TAO Zhiwei; YANG Chunshan

    2004-01-01

    Objective: To evaluate the efficacy of dynamic multi-slice spiral computed tomography (MSCT)for providing quantitative information about blood flow patterns of solitary pulmonary nodules (SPNs)and differentiating solitary pulmonary nodules (SPNs). Methods: 37 patients with SPNs (diameter≤4cm; 24 with maliagnant; 6 with benign; 7 with inflammatory) underwent multi-location dynamic contrast material-enhanced (90 mL, 4 mL/s) serial CT. Peak height and ratio of peak height of the SPN to that of the aorta were measured. Precontrast attenuation was recorded. Perfusion was calculated from the maximum gradient of the time-attenuation curve and the peak height of the aorta. Results: Peak heights of malignant (37.98 HU±17.97) and inflammatory (43.86 HU±14.20) SPNs were significantly higher than those of benign SPNs (5.65 HU±6.43) (P<0.001; P<0.001). No statistically significant difference in the peak height was found between malignant and inflammatory SPNs (P=0.647>0.01). SPN-to-aorta ratio in inflammatory SPNs (20.78%±4.14) was significantly higher than that in benign (2.00%±2.26) and malignant (14.63%±6.22) SPNs (P<0.001; P=0.021<0.05). SPN-to-aorta ratio in malignant SPNs was significantly higher than that in benign SPNs (P<0.001). Perfusion value in inflammatory SPNs [78.39 mL/(min.100g)±55.18] was significantly higher than that of benign [2.13 mL/(min.100g)±2.84] and malignant [33.91mL/(min.100g)±15.58] SPNs (P<0.001; P=0.001<0.01). Perfusion value in malignant SPNs was significantly higher than that in benign SPNs (P<0.001). Precontrast attenuations of inflammatory (39.36HU±9.57)and benign (37.73 HU±8.39) SPNs were lower than that of malignant SPNs (45.73 HU±4.21)(P=0.04<0.05; P=0.014<0.05). No statistically significant difference in the precontrast attenuation was found between benign and inflammatory SPNs (P=0.836>0.01). Conclusion: MSCT provides quantitative information about blood flow patterns of solitary pulmonary nodules

  13. Current State and Progress of Coronary Angiography in Multi-slice Spiral Computed Tomography Imaging Techniques%多排螺旋CT在冠状动脉成像技术中的现状与进展

    Institute of Scientific and Technical Information of China (English)

    胡斌; 徐文坚; 陈海松

    2012-01-01

    多层螺旋CT( mulil slice spiral CT,MSCT)技术的进步为无创性冠状动脉造影提供了广阔的前景,临床应用备受关注.特别是64层CT的出现,空间分辨率、时间分辨率大大提高,心电门控技术及三维后处理技术拓宽了CT在冠状动脉成像中的应用范围.本文阐述了CT在冠状动脉成像技术及影响因素,并对其现状及进展情况作综述.%Multi-detector row CT imaging techniques has great potential for development of noninvasive imaging of the coronary arteries. Coronary CT angiography in clinical utility field was paid highly attention to. Especially current computed tomography (64 slice CT) techniques combine high speed and spatial resolution with electrocardiography synchronization and three-dimensional post processing technology, the scope of coronary CT angiography was widen. This review article will describe the coronary angiography technology of multi-detector row CT and the factors as they relate to the current and future role of coronary CT angiography.

  14. Coronary artery aneurysm and type-A aortic dissection demonstrated by retrospectively ECG-gated multislice spiral CT

    Energy Technology Data Exchange (ETDEWEB)

    Fallenberg, Eva Maria; Juergens, Kai Uwe; Fischbach, Roman [Department of Clinical Radiology, University Hospital Muenster (Germany); Wichter, Thomas [Department of Cardiology and Angiology, University Hospital Muenster (Germany); Scheld, Hans H. [Department of Thoracic and Cardiovascular Surgery, University Hospital Muenster (Germany)

    2002-01-01

    The case of a 40-year-old male patient with a coronary aneurysm of the proximal left descending artery (LAD) combined with circumferential type-A dissection of the ascending aorta is reported. Computed tomography angiography of the coronary arteries was performed using multislice spiral computed tomography (MSCT) with retrospective ECG gating. Anatomical relations of the LAD aneurysm as well as the origin of the left coronary artery from the false lumen of the dissection were well depicted for planning of the surgical intervention using this new noninvasive imaging modality. (orig.)

  15. Time-Mean Helicity Distribution in Turbulent Swirling Jets

    Directory of Open Access Journals (Sweden)

    V. Tesař

    2005-01-01

    Full Text Available Helicity offers an alternative approach to investigations of the structure of turbulent flows. Knowledge of the spatial distribution of the time-mean component of helicity is the starting point. Yet very little is known even about basic cases in which Helicity plays important role, such as the case of a swirling jet. This is the subject of the present investigations, based mainly on numerical flowfield computations. The region of significantly large time-mean helicity density is found only in a rather small region reaching to several nozzle diameters downstream from the exit. The most important result is the similarity of the helicity density profiles. 

  16. Shearing Wind Helicity and Thermal Wind Helicity

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Helicity is defined as H=V.ω, where V and ω are the velocity and vorticity vectors, respectively.Many works have pointed out that the larger the helicity is, the longer the life cycle of the weather system is. However, the direct relationship of the helicity to the evolution of the weather system is not quite clear. In this paper, the concept of helicity is generalized as shearing wind helicity (SWH). Dynamically,it is found that the average SWH is directly related to the increase of the average cyclonic rotation of the weather system. Physically, it is also pointed out that the SWH, as a matter of fact, is the sum of the torsion terms and the divergence term in the vorticity equation. Thermal wind helicity (TWH), as a derivative of SWH, is also discussed here because it links the temperature field and the vertical wind field. These two quantities may be effective for diagnosing a weather system. This paper applies these two quantities in cylindrical coordinates to study the development of Hurricane Andrew to validate their practical use. Through analyzing the hurricane, it is found that TWH can well describe the characteristics of the hurricane such as the strong convection and release of latent heat. SWH is not only a good quantity for diagnosing the weather system, but also an effective one for diagnosing the development of the hurricane.

  17. Spin versus helicity in processes involving transversity

    CERN Document Server

    Mekhfi, Mustapha

    2011-01-01

    We construct the spin formalism in order to deal in a direct and natural way with processes involving transversity which are now of increasing popularity. The helicity formalism which is more appropriate for collision processes of definite helicity has been so far used also to manage processes with transversity, but at the price of computing numerous helicity amplitudes generally involving unnecessary kinematical variables.In a second step we work out the correspondence between both formalisms and retrieve in another way all results of the helicity formalism but in simpler forms.We then compute certain processes for comparison.A special process:the quark dipole magnetic moment is shown to be exclusively treated within the spin formalism as it is directly related to the transverse spin of the quark inside the baryon.

  18. Orbital helical computed tomography in the diagnosis and management of eye trauma; La tomodensitometrie helicoidale dans le diagnostic et la gestion des trauma de l'oeil

    Energy Technology Data Exchange (ETDEWEB)

    Lakits, A.; Prokesch, R.; Scholda, C.; Bankier, A. [Vienna Univ., Dept. of Ophthalmology (Austria)

    2000-07-01

    Helical CT axial scanning with multiplanar reconstruction is accurate at detecting and localizing intraocular and orbital metallic, glass and stone foreign bodies. This imaging method aids the surgeon in choosing the surgical approach to retained intraocular and orbital foreign bodies. (N.C.)

  19. Quantitative computation of RHEED patterns

    Science.gov (United States)

    Lordi, Scott Andrew

    This thesis is concerned with the general problem of performing quantitative RHEED computations for both flat and rough surfaces using the multislice method. Modifications to the RHEED multislice method which make it into a practical technique for performing RHEED computations are described. Computation of convergent-beam RHEED patterns using the RHEED multislice method is demonstrated by application to the case of MgO (001). Computed patterns are compared (based on the overall pattern geometry) to energy-filtered Tanaka and convergent-beam patterns recorded in a transmission electron microscope. The validity of the RHEED multislice method for convergent-beam computations is demonstrated by the level of agreement achieved. The application of the RHEED multislice method combined with the edge patching algorithm to the computation of RHEED streaks from rough surfaces is demonstrated by applying it to the case of rough Fe (001) surfaces. The computations are done using the column approximation and by neglecting the scattering from steps parallel to the incident beam. The computations are set up using STM images of the surfaces from which the experimental RHEED patterns were recorded. The shapes of the diffuse parts of the computed and experimental streaks agree well. There is a discrepancy between experiment and theory in the magnitudes of the flat surface spot position peaks relative to the diffuse parts of the streaks. The shapes of the diffuse parts of the computed streaks are shown to be insensitive to the computational and potential parameters. The magnitudes of the flat surface spot position peaks are at least weakly dependent on the potential parameters and the long range height variations of the surface. This agreement conclusively demonstrates that the RHEED multislice method can be used to perform quantitative computations of RHEED streaks from real rough surfaces. An approximation method (the patchwork approximation) for doing RHEED computations, exact in

  20. Theoretical performance analysis of multislice channelized Hotelling observers

    Science.gov (United States)

    Goossens, Bart; Platiša, Ljiljana; Philips, Wilfried

    2012-02-01

    Quality assessment of 3D medical images is becoming increasingly important, because of clinical practice rapidly moving in the direction of volumetric imaging. In a recent publication, three multi-slice channelized Hotelling observer (msCHO) models are presented for the task of detecting 3D signals in multi-slice images, where each multi-slice image is inspected in a so called stack-browsing mode. The observer models are based on the assumption that humans observe multi-slice images in a simple two stage process, and each of the models implement this principle in a different way. In this paper, we investigate the theoretical performance, in terms of detection signal-to-noise-ratio (SNR) of msCHO models, for the task of detecting a separable signal in a Gaussian background with separable covariance matrix. We find that, despite the differences in architecture of the three models, they all have the same asymptotical performance in this task (i.e., when the number of training images tends to infinity). On the other hand, when backgrounds with nonseparable covariance matrices are considered, the third model, msCHOc, is expected to perform slightly better than the other msCHO models (msCHOa and msCHOb), but only when sufficient training images are provided. These findings suggest that the choice between the msCHO models mainly depends on the experiment setup (e.g., the number of available training samples), while the relation to human observers depends on the particular choice of the "temporal" channels that the msCHO models use.

  1. Helicity, Topology and Kelvin Waves in reconnecting quantum knots

    CERN Document Server

    di Leoni, P Clark; Brachet, M E

    2016-01-01

    Helicity is a topological invariant that measures the linkage and knottedness of lines, tubes and ribbons. As such, it has found myriads of applications in astrophysics and solar physics, in fluid dynamics, in atmospheric sciences, and in biology. In quantum flows, where topology-changing reconnection events are a staple, helicity appears as a key quantity to study. However, the usual definition of helicity is not well posed in quantum vortices, and its computation based on counting links and crossings of vortex lines can be downright impossible to apply in complex and turbulent scenarios. We present a new definition of helicity which overcomes these problems. With it, we show that only certain reconnection events conserve helicity. In other cases helicity can change abruptly during reconnection. Furthermore, we show that these events can also excite Kelvin waves, which slowly deplete helicity as they interact nonlinearly, thus linking the theory of vortex knots with observations of quantum turbulence.

  2. Multislice theory of fast electron scattering incorporating atomic inner-shell ionization.

    Science.gov (United States)

    Dwyer, C

    2005-09-01

    It is demonstrated how atomic inner-shell ionization can be incorporated into a multislice theory of fast electron scattering. The resulting theory therefore accounts for both inelastic scattering due to inner-shell ionization and dynamical elastic scattering. The theory uses a description of the ionization process based on the angular momentum representation for both the initial and final states of the atomic electron. For energy losses near threshold, only a small number of independent states of the ejected atomic electron need to be considered, reducing demands on computing time, and eliminating the need for tabulated inelastic scattering factors. The theory is used to investigate the influence of the collection aperture size on the spatial origin of the silicon K-shell EELS signal generated by a STEM probe. The validity of a so-called local approximation is also considered.

  3. Magnetic Helicity Conservation and Astrophysical Dynamos

    CERN Document Server

    Vishniac, E T; Vishniac, Ethan T.; Cho, Jungyeon

    2000-01-01

    We construct a magnetic helicity conserving dynamo theory which incorporates a calculated magnetic helicity current. In this model the fluid helicity plays a small role in large scale magnetic field generation. Instead, the dynamo process is dominated by a new quantity, derived from asymmetries in the second derivative of the velocity correlation function, closely related to the `twist and fold' dynamo model. The turbulent damping term is, as expected, almost unchanged. Numerical simulations with a spatially constant fluid helicity and vanishing resistivity are not expected to generate large scale fields in equipartition with the turbulent energy density. In fact, there seems to be little prospect for driving a fast dynamo in a closed box containing homogeneous turbulence. On the other hand, there is an efficient analog to the $\\alpha-\\Omega$ dynamo. Systems whose turbulence is driven by some anisotropic local instability in shearing flow, like real stars and accretion disks, and some computer simulations, ma...

  4. 胸部透视、胸部平片和MSCT对小儿气管、支气管异物的诊断价值分析%The Analysis of Diagnostic Value of Fluoroscopy of Chest, the Chest X-ray and Multislice Computed Tomography (MSCT) to the Foreign Bodies in the Trachea and Bronchi of the Children

    Institute of Scientific and Technical Information of China (English)

    魏相磊; 武玉丽

    2014-01-01

    Objective To explore the diagnostic value of fluoroscopy of chest, the chest X-ray and multislice computed tomography (MSCT) to the foreign bodies in the trachea and bronchi of the children, and compare the results and diagnosis accuracy to the foreign bodies in the trachea and bronchi. Methods 18 cases of suspected bronchial foreign body all given lfuoroscopy of chest, the chest X-ray and MSCT, even through axis scan images mutiplane restructuring (MPR), curved planar reformation (CPR), minimum density projection method (MinP) and CT virtual endoscopy (CTVE) etc. Image post-processing technology, and compare the images results with what be found by video bronchoscope examination. Results All cases are found foreign bodies by video bronchoscope examination. 1 case directly observed positive foreign body and 10 cases observed typical signs of indirect negative foreign body by lfuoroscopy of chest. 1 case directly observed positive foreign body and 9 cases observed typical signs of indirect negative foreign body by chest X-ray examination .meanwhile 17 cases directly observed positive foreign body by MSCT scan. Conclusion MSCT and image post-processing technology has important value in diagnosing trachea bronchial foreign body in children.%目的:探讨胸部X线透视、胸部平片和MSCT对气管支气管异物的诊断价值,比较三种方法对诊断支气管异物的正确率。方法对18例怀疑支气管异物的病例全部行胸透、胸部平片和MSCT检查,通过图像后处理工作站将MSCT轴位扫描图像进行多平面重组(MPR)、曲面重组(CPR)、最小密度投影法(MinP)和CT仿真内镜(CTVE)等图像重组,检查结果分别与支气管镜对照。结果18例经纤维支气管镜检查均发现异物。胸透直接观察到阳性异物1例,具有典型间接征象的阴性异物10例;胸部平片直接观察到阳性异物1例,具有典型间接征象的阴性异物9例;MSCT诊断支气管异物17

  5. Spiral (helical) CT of tracheo-bronchial diseases; La tomodensitometrie spiralee (helicoidale) en pathologie tracheobronchique

    Energy Technology Data Exchange (ETDEWEB)

    Remy, J.; Remy-Jardin, M.; Bonnel, F.; Masson, P. [Hopital Calmette, Service de Radiologie, 59 - Lille (France)

    2000-03-01

    The acquisition techniques, including some important dosimetric considerations, and the reconstruction methods reviewing the tomographic, broncho-graphic and endoscopic techniques are first taken into consideration. They are applied to the most usual problems and diseases encountered in the daily activity: pitfalls of interpretation of the tracheobronchial tree; management of hemoptysis; preoperative of proximal bronchial carcinoma; aids and complements to diagnostic and interventional bronchoscopy. The main purpose of this review, which merges the modern technology of spiral (helical) CT with the multislice acquisition in the very near future, consists in delivering, whenever possible, an integrated diagnostic and therapeutic approach of imaging, endoscopy and surgery. (authors)

  6. Iterative assembly of helical proteins by optimal hydrophobic packing.

    Science.gov (United States)

    Wu, G Albert; Coutsias, Evangelos A; Dill, Ken A

    2008-08-06

    We present a method for the computer-based iterative assembly of native-like tertiary structures of helical proteins from alpha-helical fragments. For any pair of helices, our method, called MATCHSTIX, first generates an ensemble of possible relative orientations of the helices with various ways to form hydrophobic contacts between them. Those conformations having steric clashes, or a large radius of gyration of hydrophobic residues, or with helices too far separated to be connected by the intervening linking region, are discarded. Then, we attempt to connect the two helical fragments by using a robotics-based loop-closure algorithm. When loop closure is feasible, the algorithm generates an ensemble of viable interconnecting loops. After energy minimization and clustering, we use a representative set of conformations for further assembly with the remaining helices, adding one helix at a time. To efficiently sample the conformational space, the order of assembly generally proceeds from the pair of helices connected by the shortest loop, followed by joining one of its adjacent helices, always proceeding with the shorter connecting loop. We tested MATCHSTIX on 28 helical proteins each containing up to 5 helices and found it to heavily sample native-like conformations. The average rmsd of the best conformations for the 17 helix-bundle proteins that have 2 or 3 helices is less than 2 A; errors increase somewhat for proteins containing more helices. Native-like states are even more densely sampled when disulfide bonds are known and imposed as restraints. We conclude that, at least for helical proteins, if the secondary structures are known, this rapid rigid-body maximization of hydrophobic interactions can lead to small ensembles of highly native-like structures. It may be useful for protein structure prediction.

  7. Modelling the Siemens SOMATOM Sensation 64 Multi-Slice CT (MSCT) Scanner

    Science.gov (United States)

    Amin, A. T. Mohd; Rahni, A. A. Abd

    2017-05-01

    Reconstructing large volumetric 3D images with minimal radiation dosage exposure with reduced scanning time has been one of the main objectives in the advancement of CT development. One of its advancement is the introduction of multi-slice arc detector geometry from a cone-beam source in third generation scanners. In solving this complex geometry, apart from the known vast computations in CT image reconstruction due to large CT images, iterative reconstruction methods are preferred compared to analytic methods due to its flexibility in image reconstruction. A scanner of interest that has this type of geometry is the Siemens SOMATOM Sensation 64 Multi-Slice CT (MSCT) Scanner, which has a total of 32 slices with 672 detector elements on each slice. In this paper, the scanner projection is modelled via the intersecting lengths between each ray (exhibited from the source to the detector elements) with the scanned image voxels, which are evaluated using the classical Siddon’s algorithm to generate the system matrix, H. This is a prerequisite to perform various iterative reconstruction methods, which involves solving the inverse problem arising from the linear equation: S = H· I; where S is the projections produced from the image, I. Due to the ‘cone-beam geometry’ along the z-axis, the effective field-of-view (FOV) with voxel dimensions (0.4×0.4×0.4) mm3 is 512×512×32 voxels. The scanner model is demonstrated by reconstructing an image from simulated projections using the analytic Feldkamp-Davis-Kress (FDK) method against basic iterative image reconstruction methods.

  8. Helical surface structures

    CERN Document Server

    Brandenburg, A; Brandenburg, Axel; Blackman, Eric G.

    2002-01-01

    Over the past few years there has been growing interest in helical magnetic field structures seen at the solar surface, in coronal mass ejections, as well as in the solar wind. Although there is a great deal of randomness in the data, on average the extended structures are mostly left-handed on the northern hemisphere and right-handed on the southern. Surface field structures are also classified as dextral (= right bearing) and sinistral (= left bearing) occurring preferentially in the northern and southern hemispheres respectively. Of particular interest here is a quantitative measurement of the associated emergence rates of helical structures, which translate to magnetic helicity fluxes. In this review, we give a brief survey of what has been found so far and what is expected based on models. Particular emphasis is put on the scale dependence of the associated fields and an attempt is made to estimate the helicity flux of the mean field vs. fluctuating field.

  9. Multislice behavioral modeling based on envelope domain for power amplifiers

    Institute of Scientific and Technical Information of China (English)

    Wang Huadong; Bao Jingfu; Wu Zhengde

    2009-01-01

    An envelope domain multislice behavioral modeling is introduced. The tradition AM-AM and AM-PM characteristics of power amplifiers are extended to envelope domain and base-band filter is applied to distortion complex envelope signal for description of the envelope memory effect. Using traditional one and two-tone tests, the coefficients of nonlinear model and the FIR filter can be extracted. At last the model has been applied to a 10 W WCDMA power amplifier to predict its output signal. And simulation results show that the model output conforms very well to the traditional transistor level simulation results.

  10. Application of the FDK algorithm for multi-slice tomographic image reconstruction; Aplicacao do algoritmo FDK para a reconstrucao de imagens tomograficas multicortes

    Energy Technology Data Exchange (ETDEWEB)

    Costa, Paulo Roberto, E-mail: pcosta@if.usp.b [Universidade de Sao Paulo (IFUSP), SP (Brazil). Inst. de Fisica. Dept. de Fisica Nuclear; Araujo, Ericky Caldas de Almeida [Fine Image Technology, Sao Paulo, SP (Brazil)

    2010-08-15

    This work consisted on the study and application of the FDK (Feldkamp- Davis-Kress) algorithm for tomographic image reconstruction using cone-beam geometry, resulting on the implementation of an adapted multi-slice computed tomography system. For the acquisition of the projections, a rotating platform coupled to a goniometer, an X-ray equipment and a digital image detector charge-coupled device type were used. The FDK algorithm was implemented on a computer with a Pentium{sup R} XEON{sup TM} 3.0 processor, which was used for the reconstruction process. Initially, the original FDK algorithm was applied considering only the ideal physical conditions in the measurement process. Then some artifacts corrections related to the projections measurement process were incorporated. The implemented MSCT system was calibrated. A specially designed and manufactured object with a known linear attenuation coefficient distribution ({mu}(r)) was used for this purpose. Finally, the implemented MSCT system was used for multi-slice tomographic reconstruction of an inhomogeneous object, whose distribution {mu}(r) was unknown. Some aspects of the reconstructed images were analyzed to assess the robustness and reproducibility of the system. During the system calibration, a linear relationship between CT number and linear attenuation coefficients of materials was verified, which validate the application of the implemented multi-slice tomographic system for the characterization of linear attenuation coefficients of distinct several objects. (author)

  11. Helicity conservation under quantum reconnection of vortex rings

    CERN Document Server

    Zuccher, Simone

    2016-01-01

    Here we show that under quantum reconnection, simulated by using the three-dimensional Gross- Pitaevskii equation, self-helicity of a system of two interacting vortex rings remains conserved. By resolving the fine structure of the vortex cores, we demonstrate that total length of the vortex system reaches a maximum at the reconnection time, while both writhe helicity and twist helicity remain separately unchanged throughout the process. Self-helicity is computed by two independent methods, and topological information is based on the extraction and analysis of geometric quantities such as writhe, total torsion and intrinsic twist of the reconnecting vortex rings.

  12. Helical superconducting black holes.

    Science.gov (United States)

    Donos, Aristomenis; Gauntlett, Jerome P

    2012-05-25

    We construct novel static, asymptotically five-dimensional anti-de Sitter black hole solutions with Bianchi type-VII(0) symmetry that are holographically dual to superconducting phases in four spacetime dimensions with a helical p-wave order. We calculate the precise temperature dependence of the pitch of the helical order. At zero temperature the black holes have a vanishing entropy and approach domain wall solutions that reveal homogenous, nonisotropic dual ground states with an emergent scaling symmetry.

  13. Detecting anomalous traders using multi-slice network analysis

    Science.gov (United States)

    Sun, Xiao-Qian; Shen, Hua-Wei; Cheng, Xue-Qi; Zhang, Yuqing

    2017-05-01

    Manipulation is an important issue for both developed and emerging stock markets. Many efforts have been made to detect manipulation in stock market. However, it is still an open problem to identify the fraudulent traders, especially when they collude with each other. In this paper, we focus on the problem of identifying anomalous traders using the transaction data of 8 manipulated stocks and 42 non-manipulated stocks during a one-year period. For each stock, we construct a multi-slice trading network to characterize the daily trading behavior and the cross-day participation of each trader. Comparing the multi-slice trading network of manipulated stocks and non-manipulated stocks with their randomized version, we find that manipulated stocks exhibit high number of trader pairs that trade with each other in multiple days and high deviation from randomized network at correlation between trading frequency and trading activity. These findings are effective at distinguishing manipulated stocks from non-manipulated ones and at identifying anomalous traders.

  14. Design Consideration and Reconstruction Method for Double-source Double-multislice Spiral CT

    Institute of Scientific and Technical Information of China (English)

    LIU Zun-gang; ZHAO Jun; ZHUANG Tian-ge

    2007-01-01

    To accelerate the scan speed and improve the image quality, a new type of CT configuration, "doublesource double-multislice spiral CT" (DSDMS-CT), which is based on two sets of single-source multislice spiral CT was proposed with a special reconstruction algorithm.Simulation results using the fan-beam filtered backprojection algorithm with a special interpolation method were presented for both single-source multislice spiral CT and DSDMS-CT.The results of new CT model show that it scans faster than the traditional spiral CT and has a better slice sensitivity profile (SSP) with larger pitch value.

  15. Helicity, Reconnection, and Dynamo Effects

    Energy Technology Data Exchange (ETDEWEB)

    Ji, Hantao

    1998-11-01

    The inter-relationships between magnetic helicity, magnetic reconnection, and dynamo effects are discussed. In laboratory experiments, where two plasmas are driven to merge, the helicity content of each plasma strongly affects the reconnection rate, as well as the shape of the diffusion region. Conversely, magnetic reconnection events also strongly affect the global helicity, resulting in efficient helicity cancellation (but not dissipation) during counter-helicity reconnection and a finite helicity increase or decrease (but less efficiently than dissipation of magnetic energy) during co-helicity reconnection. Close relationships also exist between magnetic helicity and dynamo effects. The turbulent electromotive force along the mean magnetic field (alpha-effect), due to either electrostatic turbulence or the electron diamagnetic effect, transports mean-field helicity across space without dissipation. This has been supported by direct measurements of helicity flux in a laboratory plasma. When the dynamo effect is driven by electromagnetic turbulence, helicity in the turbulent field is converted to mean-field helicity. In all cases, however, dynamo processes conserve total helicity except for a small battery effect, consistent with the observation that the helicity is approximately conserved during magnetic relaxation.

  16. Detección precoz por Tomografía Computada Cuantitativa Multicorte de alteraciones en la densidad mineral ósea, inducidas por una dieta aterogénica, en un modelo experimental en ratas en crecimiento Multislice Quantitative Computed Tomography allozos early detectíon of bone mineral density alterations induced by atherogenic diet in a growing rat experimental model

    Directory of Open Access Journals (Sweden)

    Marcelo Joaquín Gubert

    2012-03-01

    Full Text Available Propósito. Demostrar la utilidad de la tomografía computada cuantitativa multicorte (QCT-MC en la detección precoz de alteraciones en la densidad mineral ósea (DMO mandibular, inducidas por una dieta aterogénica, en un modelo experimental en ratas en crecimiento. Materiales y Métodos. Ratas Wistar macho (n=16 al destete, loteadas por peso en 2 grupos: Control (C y experimental (E; peso promedio inicial sin diferencias significativas (p > 0,05; recibieron a libre demanda: C, dieta stock para roedores y E, dieta aterogénica por 3 semanas. Se monitorearon zoometría (peso y longitud corporales y consumo de dieta (g/100 g rata/día. A las 3 semanas en suero (mg/dL, se evaluó el perfil lipídico-lipoproteico: colesterol total (col-T, triglicéridos (TG, col HDL y noHDL, y la QCT-MC (Philips 64 CT, cuantificado con eFilm Workstation 2.1 de siete zonas mandibulares (ZM: n° 1 a 4, desde forámen mentoniano hacia mandibular; n° 5, proceso coronoide; n° 6, proceso condilar; n° 7, proceso angular. Se realizó análisis estadístico Pearson: correlación entre DMO de cada ZM y valor sérico de col-T (nivel de significación p 0,05. Los coeficientes de correlación (r y respectivos niveles de significación (p mostraron, en cinco de siete ZM, ser significativos: ZM 1: -0,580 (p = 0,019, ZM 2: -0,709 (p = 0,002, ZM 3: -0,635 (p = 0,008, ZM 5: -0.674 (p = 0,004, ZM 6: -0,564 (p = 0,023. Conclusiones. Estos resultados sugieren que la QCT-MC es un método de diagnóstico por imágenes que permite detectar precozmente alteraciones inducidas por una dieta aterogénica en la arquitectura ósea de la mandíbula. La correlación inversa entre la DMO y el col-T indicaría una asociación entre el consumo de una dieta aterogénica y posibles disfunciones témporo-mandibulares.Purpose. To demónstrate the utility of Multislice Quantitative Computed Tomography (MS-QCT in the early detection of mandibular bone mineral density (BMD alterations induced by an

  17. The value of multi-slice spiral computed tomography portography in assessing severity of liver cirrhosis and predicting episode risks of hepatic encephalopathy%多层螺旋CT门静脉造影评估肝硬化病变程度及预测肝性脑病发病风险的价值

    Institute of Scientific and Technical Information of China (English)

    刘文娜; 王剑; 冯义朝; 戴光荣; 宁涛

    2014-01-01

    Objective To explore the clinical value of multi-slice spiral computed tomography portography (MSCTP) in assessing severity of liver cirrhosis and predicting episode risks of hepatic encephalopathy (HE).Methods Eighty-six patients with liver cirrhosis who were hospitalized in the Department of Gastroenterology at the Affiliated Hospital of Yan'an University were included in the study.All patients underwent 64-slice MSCTP to grade the portal vein anatomy.The West Haven criteria were used for semi-quantitative assessment of each patient's mental state.The Child-Pugh grading system was used to assess the extent of cirrhosis.Comparison of measurement data between multiple groups was made by one-way ANOVA analysis,and comparison of such between two groups was made by the Mann-Whitney U test,Ranked data were compared with the rank-sum test,and count data were compared by the Chi-Square test.Correlation analysis was performed with Spearman's correlation test.Results Comparison of the HE grade Ⅲ group and the HE grade Ⅰ group showed significant differences between the two in the diameters of left gastric vein,the splenic vein,the intrahepatic left portal vein and the intrahepatic right portal vein (P < 0.05).Comparison of the Child-Pugh grade C group and the Child-Pugh grade A group showed significant differences between the two in diameters of the left gastric vein,the splenic vein,the intrahepatic left portal vein and the intrahepatic right portal vein (P < 0.05).The diameters of the main portal vein were not significantly different between the ChildPugh grades and HE classifications (P > 0.05).The results of MSCTP did show significant differences between different HE classifications in patients with liver cirrhosis and the rate of formation of portal vein thrombosis and fistulas of the hepatic artery-portal vein (P < 0.05),.but no significant differences with the esophageal and gastric varices,varicose veins around the esophagus,and periumbilical varicose

  18. Impact of intravascular enhancement, heart rate, and calcium score on diagnostic accuracy in multislice Computed Tomography coronary angiography; Influenza di attenuazione vascolare, frequenza cardiaca e calcium score sull'accuratezza diagnostica in angiografia coronarica non invasiva mediante Tomografia Computerizzata multistrato

    Energy Technology Data Exchange (ETDEWEB)

    Cademartiri, Filippo; Mollet, Nico R.; Kriestin, Gabriel P. [Erasmus Medical Center, Rotterdam (Netherlands). Dipartimento di radiologia; Runza, Giuseppe; Bartolotta, Tommaso Vincenzo; Galia, Massimo; Midiri, Massimo [Palermo Univ., Palermo (Italy). DIBIMEL, Sezione di scienze radiologiche; Belgrano, Manuel; Pozzi Mucelli, Roberto [Trieste Univ., Trieste (Italy). Ospedale di Cattinara, Istituto di radiologia

    2005-07-15

    Purpose. To assess the effect of intravascular enhancement, heart rate, and calcium score on diagnostic accuracy in the detection of significant coronary artery stenosis using 16-row multislice computed tomography (MSCT). Materials and methods. One hundred patients (88 males; 59{+-}11 years) with suspected coronary artery disease who had undergone conventional coronary angiography (CA) and MSCT-CA were retrospectively enrolled for the study. Patients underwent a MSCT-CA, with the following protocol: collimation 16x0.75 mm, gantry rotation time 420 ms, feed/rotation 2.8 mm, kV 120, mAs 400-500. The protocol for contrast material administration was 100 ml of Iodixanol 320 mgI/nl at 4 ml/s and the scan delay was defined with a bolus tracking technique. In all patients vascular enhancement was measured in the aortic root, and the left and the right coronary arteries. The average enhancement was used to divide the population in two groups of 50 patients each, one with lower enhancement (Low), and one with higher enhancement (High). In the two groups diagnostic accuracy (per coronary segment) for the detection of significant stenosis ({>=}50% lumen reduction) was evaluated in vessels {>=}2mm in diameter using quantitative CA as the reference standard. The differences in diagnostic accuracy were compared with a Chi-square test and a p<0.05 was considered significant. Results. Of the total 1116 segments ({>=}2 mm lumen diameter), 173 presented significant stenosis. The sensitivity and specificity for the assessment of significant stenosis were 89.4% and 93.3% vs 94.3% and 97.4% in the presence of increasing intravascular enhancement, 92.8% and 96.7% vs 91.1% and 93.9% in the presence of increasing heart rate, and 89.7% and 97.6% vs 93.3% and 92.8% in the presence of increasing calcium score. Conclusions. Increasing intravascular enhancement significantly improves diagnostic accuracy in MSCT-CA. A higher heart rate lowers the specificity in the detection of significant

  19. Measurement of coronary artery calcification with multi-slice spiral computed tomography and the associated factors in maintenance hemodialysis patients%维持性血液透析患者冠状动脉钙化的评价及影响因素分析

    Institute of Scientific and Technical Information of China (English)

    郑淑蓓; 金领微; 李占园; 周志宏

    2015-01-01

    Objective To investigate the factors correlated to coronary artery calcification (CAC) in maintenance hemodialysis (MHD) patients.Methods This study included 132 patients(54 females,78 males),aged 26-94 years,who were on hemodialysis for 10-204 months(median dialysis duration 51.00 months).The parameters including calcium,phosphorus,parathyroid hormone,total cholesterol,low density lipoprotein,triglycerides,C-reactive protein (CRP),klotho,and so on were assessed.Quantification of CAC was determined by multi-slice spiral computed tomography (MSCT),known as the coronary artery calcification score (CACs).Results Ninety-two patients (69.70%) had CAC,with CACs ranging from 0 to 13 450.20.More than 30% patients experienced one even a variety of cardiovascular and cerebrovascular diseases.A positive correlation was observed between the degree of CAC and the incidence of cardiovascular and cerebrovascular diseases.Whereas a positive correlation existed between CACs and age (r=0.347,P=0.000),duration of hemodialysis (r=0.245,P=0.005),systolic blood pressure (r=0.184,P=0.034),diabetes history (r=0.211,P=0.015),phosphorus (r=0.262,P=0.002),calcium-phosphorus product (r=0.247,P=0.004);and a negative correlation between CACs and klotho level (r=-0.294,P=0.001).Multivariate logistic regression analysis showed that the main factor influencing the degree of CAC in MHD patients was age.Conclusions CAC is common and widespread in hemodialysis patients,who are often accompanied by cardiovascular and cerebrovascular diseases.The prevalence rate of cardiovascular and cerebrovascular diseases increases with the aggravation of CAC degree.Age,duration of hemodialysis,systolic blood pressure,diabetes history,disturbance of calcium and phosphorus metabolism and klotho are correlated with the severity of CAC.Age is an independent risk factor of CAC degree.%目的 探讨影响维持性血液透析(MHD)患者冠状动脉钙化(CAC)的相关因素.方法 收集2012年12月至2014年8月在

  20. Values of multi-slice spiral computed tomography on predicting hypovolemic shock in patients with severe multiple trauma%多层螺旋CT对严重多发伤患者低血容量性休克的预测价值

    Institute of Scientific and Technical Information of China (English)

    李阳; 张连阳; 王毅; 张伟国

    2013-01-01

    Objective To investigate the value of multi-slice spiral computed tomography (MSCT) on predicting hypovolemic shock in patients with severe multiple trauma. Methods The clinical and MSCT data of 63 patients with severe multiple trauma admitted to the Trauma Center from Jan. 2008 to Dec. 2011 were retrospectively reviewed. According to the occurrence of hypovolemic shock in 24 hours after CT scan, the patients were divided into shock group (n=34) and stable group (n=29). Blood pressure, heart rate, shock index and injury severity score (ISS) on admission were collected and analyzed. Transverse (T) and anteroposterior (AP) diameter of inferior vena cava (IVC), diameter of abdominal aorta, CT values of enhanced CT of abdominal organs both in early and late phase were measured. The differences of aforementioned parameters between the two groups were compared by Student's t test. The values of above indexes showing significant difference between the two groups on predicting hypovolemic shock were analyzed by using receiver operating characteristic (ROC) curve and logistic regression analysis. Results The shock index, ISS and collapsibility index (T/AP) of IVC in 4 abdominal levels were significantly greater in shock group than in stable group (I'<0.05). In early phase of enhanced CT, the mean CT value of spleen was significantly lower in shock group (93 ± 16HU) than in stable group (112 ± 24HU, P<0.0l), while the mean CT value of adrenal gland was higher in shock group (153 ± 35HU) than in stable group (131 ± 24HU, P<0.0l). In delayed phase, the mean CT value of renal medulla was significantly lower in shock group (193 ± 57HU) than in stable group (228 ± S3HU, P<0.05). The diagnostic cutoff value of ROC curve of shock index, ISS, collapsibility index (T/AP) of IVC, CT value of spleen and adrenal gland in early phase, CT value of renal medulla in delayed phase were 1.19, 19.5, 3.02, 115HU, 150HU and 184HU, respectively. Logistic regression analysis showed that ISS

  1. Contrast investigation of multi-slice spiral CT perfusion imaging and pathological findings in VX2 soft-tissue tumor of rabbits

    Institute of Scientific and Technical Information of China (English)

    Jingfeng Zhang; Renfa Wang; Min Wang; Jing Zhang; Jinmei Sang

    2005-01-01

    Objective: To perform a contrast investigation of multi-slice spiral CT (MSCT) perfusion imaging and pathological findings in VX2 soft-tissue tumor of rabbits, and discuss the applicative value of multi-slice spiral CT perfusion imaging in soft-tissue tumors. Methods: 8 Newzealand white rabbits were implanted with 0.1 ml VX2 tumor tissue suspension in bilateral proximal thighs. 14 days and 21 days later, CT plain scan and perfusion scan were performed on these rabbits respectively, then the images were transmitted to AW4.0 workstation, the functional maps and perfusion parameters including blood flow (BF), blood volume (BV), mean transit time(MTT) and permeability surface (PS) were computed and analyzed. Subsequently, the rabbits were sacrificed, the tumors of which were taken out for pathological examination. The correlation between MSCT functional parametric images and pathological findings was analyzed.Results: All the values of BF, BV and PS of VX2 soft-tissue tumors were obviously higher while the MTT-values were lower than those of the normal muscular tissues significantly ( P < 0.001). Conclusion: Multi-slice spiral CT perfusion imaging is an accurate, convenient and relatively safe functional imaging technique, which can give a quantitative assessment to blood perfusion and angiogenesis of soft-tissue tumors.

  2. Mathisson's helical motions demystified

    CERN Document Server

    Costa, L Filipe O; Zilhão, Miguel

    2012-01-01

    The motion of spinning test particles in general relativity is described by Mathisson-Papapetrou-Dixon equations, which are undetermined up to a spin supplementary condition, the latter being today still an open question. The Mathisson-Pirani (MP) condition is known to lead to rather mysterious helical motions which have been deemed unphysical, and for this reason discarded. We show that these assessments are unfounded and originate from a subtle (but crucial) misconception. We discuss the kinematical explanation of the helical motions, and dynamically interpret them through the concept of hidden momentum, which has an electromagnetic analogue. We also show that, contrary to previous claims, the frequency of the helical motions coincides exactly with the zitterbewegung frequency of the Dirac equation for the electron.

  3. Helical plasma thruster

    Energy Technology Data Exchange (ETDEWEB)

    Beklemishev, A. D., E-mail: bekl@bk.ru [Budker Institute of Nuclear Physics SB RAS, Novosibirsk (Russian Federation)

    2015-10-15

    A new scheme of plasma thruster is proposed. It is based on axial acceleration of rotating magnetized plasmas in magnetic field with helical corrugation. The idea is that the propellant ionization zone can be placed into the local magnetic well, so that initially the ions are trapped. The E × B rotation is provided by an applied radial electric field that makes the setup similar to a magnetron discharge. Then, from the rotating plasma viewpoint, the magnetic wells of the helically corrugated field look like axially moving mirror traps. Specific shaping of the corrugation can allow continuous acceleration of trapped plasma ions along the magnetic field by diamagnetic forces. The accelerated propellant is expelled through the expanding field of magnetic nozzle. By features of the acceleration principle, the helical plasma thruster may operate at high energy densities but requires a rather high axial magnetic field, which places it in the same class as the VASIMR{sup ®} rocket engine.

  4. Advanced computing in electron microscopy

    CERN Document Server

    Kirkland, Earl J

    2010-01-01

    This book features numerical computation of electron microscopy images as well as multislice methods High resolution CTEM and STEM image interpretation are included in the text This newly updated second edition will bring the reader up to date on new developments in the field since the 1990's The only book that specifically addresses computer simulation methods in electron microscopy

  5. Multislice CT brain image registration for perfusion studies

    Science.gov (United States)

    Lin, Zhong Min; Pohlman, Scott; Chandra, Shalabh

    2002-04-01

    During the last several years perfusion CT techniques have been developed as an effective technique for clinically evaluating cerebral hemodynamics. Perfusion CT techniques are capable of measurings functional parameters such as tissue perfusion, blood flow, blood volume, and mean transit time and are commonly used to evaluate stroke patients. However, the quality of functional images of the brain frequently suffers from patient head motion. Because the time window for an effective treatment of stroke patient is narrow, a fast motion correction is required. The purpose of the paper is to present a fast and accurate registration technique for motion correction of multi-slice CT and to demonstrate the effects of the registration on perfusion calculation.

  6. 多排螺旋CT在胆源性胆囊-十二指肠瘘诊断中的临床价值%Clinical value of multi-slice computed tomography in the diagnosis of biliary gallbladder-duodenal fistula

    Institute of Scientific and Technical Information of China (English)

    王均庆; 郑庆华; 陆风旗; 张雷; 张追阳; 丁忠; 余迅

    2015-01-01

    Objective To summarize the characteristics and clinical value of multi-slice spiral computed tomography (MSCT) examination in the biliary gallbladder-duodenal fistula.Methods The imaging data of 28 patients with gallbladder-duodenal fistula who were admitted to the Wuxi No.2 Hospital of Nanjing Medical University between June 2012 and March 2015 were retrospectively analyzed.All the 28 patients received MSCT examinations,and the imaging changes were observed and analyzed,including the location of lesions,figures of fistulous tract,shrinking or enlarging gallbladder,pneumotosis and stones of gallbladder or bile duct.Results Of the 28 patients,fistula located at the duodenal bulb were detected in 14 patients,junction of the bulb and the descending part of the duodenum in 2 patients,ascending duodenum in 7 patients,horizontal part in 5 patients.Indirect signs of biliary gallbladder-duodenal fistula included that gallbladder volume in 28 patients was significantly reduced,cross sectional area of gallbladder was 2 cm × 1 cm-6 cm × 2 cm,and gallbladder wall was thickened with an average thickness of 5 mm (range,4-9 mm).Adhesion of gallbladder and duodenum,unclear boundary,structure disorder and visible effusion surrounding gallbladder were detected.Among 21 patients with biliary gas,19 patients had pneumotosis of gallbladder and 17 had biliary pneumatosis.Biliary stones were detected in 23 patients including cholecystolithiasis in 19 patients,gallbladder neck stones in 6 patients,common bile duct stones in 13 patients and intra-and extra-hepatic cholangiolithiasis in 1 patient.The diverticulum signs appeared in the duodenum of 11 patients.The direct signs of MSCT in the biliary gallbladder-duodenal fistula included that fistulous tract of 13 patients clearly showed and some were dumbbell-shaped.Two and 2 patients were complicated with gallstone ileus and multiple liver abscesses,respectively.The diagnostic results of MSCT in 28 patients were compared with the results

  7. 3D Reconstruction in Spiral Multislice CT Scans

    Directory of Open Access Journals (Sweden)

    M. Ghafouri

    2005-08-01

    Full Text Available Introduction & Background: The rapid development of spiral (helical computed tomography (CT has resulted in exciting new applications for CT. One of these applications, three-dimensional (3D CT with volume ren-dering, is now a major area of clinical and academic interest. One of the greatest advantages of spiral CT with 3D volume rendering is that it provides all the necessary information in a single radiologic study (and there-fore at the lowest possible price in cases that previously required two or more studies. Three-dimensional vol-ume rendering generates clinically accurate and immediately available images from the full CT data set with-out extensive editing. It allows the radiologist and clinician to address specific questions concerning patient care by interactively exploring different aspects of the data set. Three-dimensional images integrate a series of axial CT sections into a form that is often easier to interpret than the sections themselves and can be made to appear similar to other more familiar images such as catheter angiograms. The data are organized into a 3D matrix of volume elements (voxels. The screen of the computer monitor is a 2D-surface composed of discrete picture elements (pixels. Presenting what is stored in memory (ie, floating within the monitor on a 2D-screen is a challenge, but it is the very problem that 3D reconstruc-tion software has creatively solved. Voxel selection is usually accomplished by projecting lines (rays through the data set that correspond to the pixel matrix of the desired 2D image. Differences in the images produced with various 3D rendering techniques are the result of variations in how voxels are selected and weighted. In this article, I compare 3D volume rendering of spiral CT data with other rendering techniques (shaded surface display, maximum intensity projection and present a brief history of 3D volume rendering and discuss the im-plementation of this promising technology in terms of

  8. Effective dose estimation in whole-body multislice CT in paediatric trauma patients

    Energy Technology Data Exchange (ETDEWEB)

    Munk, Robin D.; Saueressig, Ulrich; Kotter, Elmar; Langer, Mathias; Bley, Thorsten A. [University Hospital, Department of Radiology, Freiburg im Breisgau (Germany); Strohm, Peter C.; Zwingmann, Joern; Suedkamp, Norbert P. [University Hospital, Department of Orthopaedic and Trauma Surgery, Freiburg im Breisgau (Germany); Uhl, Markus [University Hospital, Department of Radiology, Section of Paediatric Radiology, Freiburg im Breisgau (Germany)

    2009-03-15

    The number of multislice CT (MSCT) scans performed in polytraumatized children has increased rapidly. There is growing concern regarding the radiation dose in MSCT and its long-term consequences, especially in children. To determine the effective dose to polytraumatized children who undergo whole-body MSCT. A total of 51 traumatized children aged 0-16 years underwent a polytrauma protocol CT scan between November 2004 and August 2006 at our institution. The effective dose was calculated retrospectively by a computer program (CT-Expo 1.5, Hannover, Germany). The mean effective dose was 20.8 mSv (range 8.6-48.9 mSv, SD{+-}7.9 mSv). There was no statistically significant difference in the effective dose between male and female patients. Whole-body MSCT is a superior diagnostic tool in polytraumatized children with 20.8 mSv per patient being a justified mean effective dose. In a potentially life-threatening situation whole-body MSCT provides the clinicians with relevant information to initiate life-saving therapy. Radiologists should use special paediatric protocols that include dose-saving mechanisms to keep the effective dose as low as possible. Further studies are needed to examine and advance dose-saving strategies in MSCT, especially in children. (orig.)

  9. A Hybrid Method for Segmentation and Visualization of Teeth in Multi-Slice CT scan Images

    Directory of Open Access Journals (Sweden)

    Mohammad Hosntalab

    2009-12-01

    Full Text Available Introduction: Various computer assisted medical procedures such as dental implant, orthodontic planning, face, jaw and cosmetic surgeries require automatic quantification and volumetric visualization of teeth. In this regard, segmentation is a major step. Material and Methods: In this paper, inspired by our previous experiences and considering the anatomical knowledge of teeth and jaws, we propose a hybrid technique for teeth segmentation and visualization in CT volumetric data. The major steps of the proposed techniques are as follows: (1 Separation of teeth in CT dataset; (2 Initial segmentation of teeth in panoramic projection; (3 Final segmentation of teeth in CT dataset; (4 3D visualization of teeth. Results: The proposed algorithm was evaluated in 30 multi-slice CT datasets. Segmented images were compared with manually outlined contours. In order to evaluate the proposed method, we utilized several common performance measures such as sensitivity, specificity, precision, accuracy and mean error rate. The experimental results reveal the effectiveness of the proposed method. Discussion and Conclusion: In the proposed algorithm, the variationallevel set technique was utilized to trace the contour of the teeth. In view of the fact that this technique is based on the characteristics of the overall region of the tooth image, it is possible to extract a very smooth and accurate tooth contour using this technique. For the available datasets, the proposed technique was more successful in teeth segmentation compared to previous techniques.

  10. Multi-slice CT angiography by triple-phase enhancement in preoperative evaluation of hepatocellular carcinoma

    Institute of Scientific and Technical Information of China (English)

    XIAO Xi-gang; HAN Xue; SHAN Wei-dong; LI An-yuan

    2005-01-01

    Background Triple-phase enhancement of multi-slice computed tomography (MSCT) has markedly improved the diagnostic accuracy of hepatocellular carcinoma (HCC), and MSCT angiography (MSCTA) has been proved useful in detecting vascular anatomy noninvasively. This study aimed to explore the value of MSCTA by triple-phase enhancement in preoperative evaluation of HCC.Methods Fifty-six consecutive cases of primary HCC scheduled for resection were studied with MSCTA by triple-phase enhancement. The raw data images were processed on a workstation for multiplanar reconstruction (MPR) and three-dimensional (3D) reconstruction. The findings after processing of the data were compared with those after surgery or intraoperative sonography. Results The false positive rate of MSCTA by triple-phase enhancement was 10.1% and its false negative rate was 4.3% in detecting HCC. No significant difference was observed in MSCTA and surgery or intraoperative sonography in detecting vascular anatomy anomalies and pathologic variations, whereas significant difference was found in detecting bile duct invasion with MSCT compared to intraoperative sonography.Conclusions MSCTA by triple-phase enhancement not only improves the detection of HCC, but also provides valuable preoperative information about hepatic vascular architecture and parenchyma. MSCTA by triple-phase enhancement is worthy of application as a non-invasive method in preoperative evaluation of HCC.

  11. Flat Helical Nanosieves

    CERN Document Server

    Mei, Shengtao; Hussain, Sajid; Huang, Kun; Ling, Xiaohui; Siew, Shawn Yohanes; Liu, Hong; Teng, Jinghua; Danner, Aaron; Qiu, Cheng-Wei

    2016-01-01

    Compact and miniaturized devices with flexible functionalities are always highly demanded in optical integrated systems. Plasmonic nanosieve has been successfully harnessed as an ultrathin flat platform for complex manipulation of light, including holography, vortex generation and non-linear processes. Compared with most of reported single-functional devices, multi-functional nanosieves might find more complex and novel applications across nano-photonics, optics and nanotechnology. Here, we experimentally demonstrate a promising roadmap for nanosieve-based helical devices, which achieves full manipulations of optical vortices, including its generation, hybridization, spatial multiplexing, focusing and non-diffraction propagation etc., by controlling the geometric phase of spin light via over 121 thousands of spatially-rotated nano-sieves. Thanks to such spin-conversion nanosieve helical elements, it is no longer necessary to employ the conventional two-beam interferometric measurement to characterize optical ...

  12. Helices and vector bundles

    CERN Document Server

    Rudakov, A N

    1990-01-01

    This volume is devoted to the use of helices as a method for studying exceptional vector bundles, an important and natural concept in algebraic geometry. The work arises out of a series of seminars organised in Moscow by A. N. Rudakov. The first article sets up the general machinery, and later ones explore its use in various contexts. As to be expected, the approach is concrete; the theory is considered for quadrics, ruled surfaces, K3 surfaces and P3(C).

  13. Magnetic Helicities and Dynamo Action in Magneto-rotational Turbulence

    Science.gov (United States)

    Bodo, G.; Cattaneo, F.; Mignone, A.; Rossi, P.

    2017-07-01

    We examine the relationship between magnetic flux generation, taken as an indicator of large-scale dynamo action, and magnetic helicity, computed as an integral over the dynamo volume, in a simple dynamo. We consider dynamo action driven by magneto-rotational turbulence (MRT) within the shearing-box approximation. We consider magnetically open boundary conditions that allow a flux of helicity in or out of the computational domain. We circumvent the problem of the lack of gauge invariance in open domains by choosing a particular gauge—the winding gauge—that provides a natural interpretation in terms of the average winding number of pairwise field lines. We use this gauge precisely to define and measure the helicity and the helicity flux for several realizations of dynamo action. We find in these cases that the system as a whole does not break reflectional symmetry and that the total helicity remains small even in cases when substantial magnetic flux is generated. We find no particular connection between the generation of magnetic flux and the helicity or the helicity flux through the boundaries. We suggest that this result may be due to the essentially nonlinear nature of the dynamo processes in MRT.

  14. 直接采用二维多截面时步法有限元的斜槽异步电机模型%Direct Modeling of Induction Motors with Skewed Rotor Slots Using 2-D Multi-Slice Model and Time Stepping FEM

    Institute of Scientific and Technical Information of China (English)

    傅为农; 江建中

    2000-01-01

    The geometrical feature of the skewed rotor slots in induction motors makes the 2-dimensional (2-D) finite element method (FEM) not directly applicable. Based on the multi-slice model in this paper, a time stepping 2-D eddy-current FEM is described to study the steady-state operation and the starting process of induction machines with skewed rotor slots. The fields of the multi-slices are solved in parallel, and thus the effects of skewed slots and eddy-current can be taken into account directly. The basic formulas for the multi-slice model are derived. Special technique to reduce computation time in solving the coupled system equations is also described. The results obtained by using the program developed have very good correlation with the test data.

  15. Tomografia computadorizada helicoidal dos seios paranasais na criança: avaliação das sinusopatias inflamatórias Helical computed tomography of the paranasal sinuses in children: evaluation of sinus inflammatory diseases

    Directory of Open Access Journals (Sweden)

    Luiz Dias Dutra

    2002-06-01

    Full Text Available Neste estudo foi feita avaliação retrospectiva de 71 casos selecionados de pacientes pediátricos, maiores de um ano e menores de sete anos, que realizaram exame de tomografia computadorizada helicoidal dos seios paranasais no período de março de 1997 a abril de 1998, apresentando quadro clínico de sinusopatia inflamatória aguda recorrente e sinusopatia inflamatória crônica. Foram correlacionados os quadros clínicos com os achados da tomografia computadorizada helicoidal, avaliando a pneumatização dos seios paranasais, os complexos óstio-meatais, as variações anatômicas, o estado da superfície mucosa e a extensão lesional. Os achados tomográficos de maior prevalência foram o velamento total ou parcial de uma ou mais cavidades paranasais (92,9%, seguido da hipertrofia da mucosa de revestimento (67,6%. Houve, na maioria dos casos, associação entre a sinusopatia inflamatória e a obstrução dos complexos óstio-meatais (53,5%. As variações anatômicas foram identificadas já a partir de um ano, com predomínio dos desvios do septo nasal (14,1%, estando correlacionadas às sinusopatias inflamatórias em cerca de 71% dos pacientes.We conducted a retrospective analysis of 71 selected pediatric patients, aged 1 to 7 years, which were submitted to helical computed tomography examination of the paranasal sinuses in the period between March, 1997 and April, 1998 due to recurrent acute sinusitis and chronic sinusitis. Clinical and helical computed tomography findings were compared by evaluating the pneumatization of the paranasal sinuses, ostiomeatal complexes, anatomic variants, the status of mucosal surface and lesion extension. The most common CT findings were total or partial opacification of one or more paranasal cavities (92.9%, followed by mucosal thickening (67.6%. In the majority of cases there was association between sinusitis and ostiomeatal obstruction. Anatomic variants were identified from the age of one year. The most

  16. Helicity and alpha-effect by current-driven instabilities of helical magnetic fields

    CERN Document Server

    Gellert, M; Hollerbach, R

    2011-01-01

    Helical magnetic background fields with adjustable pitch angle are imposed on a conducting fluid in a differentially rotating cylindrical container. The small-scale kinetic and current helicities are calculated for various field geometries, and shown to have the opposite sign as the helicity of the large-scale field. These helicities and also the corresponding $\\alpha$-effect scale with the current helicity of the background field. The $\\alpha$-tensor is highly anisotropic as the components $\\alpha_{\\phi\\phi}$ and $\\alpha_{zz}$ have opposite signs. The amplitudes of the azimuthal $\\alpha$-effect computed with the cylindrical 3D MHD code are so small that the operation of an $\\alpha\\Omega$ dynamo on the basis of the current-driven, kink-type instabilities of toroidal fields is highly questionable. In any case the low value of the $\\alpha$-effect would lead to very long growth times of a dynamo in the radiation zone of the Sun and early-type stars of the order of mega-years.

  17. The Writhe of Helical Structures in the Solar Corona

    Science.gov (United States)

    Toeroek, T.; Berger, M. A.; Kliem, B.

    2010-01-01

    Context. Helicity is a fundamental property of magnetic fields, conserved in ideal MHD. In flux rope topology, it consists of twist and writhe helicity. Despite the common occurrence of helical structures in the solar atmosphere, little is known about how their shape relates to the writhe, which fraction of helicity is contained in writhe, and how much helicity is exchanged between twist and writhe when they erupt. Aims. Here we perform a quantitative investigation of these questions relevant for coronal flux ropes. Methods. The decomposition of the writhe of a curve into local and nonlocal components greatly facilitates its computation. We use it to study the relation between writhe and projected S shape of helical curves and to measure writhe and twist in numerical simulations of flux rope instabilities. The results are discussed with regard to filament eruptions and coronal mass ejections (CMEs). Results. (1) We demonstrate that the relation between writhe and projected S shape is not unique in principle, but that the ambiguity does not affect low-lying structures, thus supporting the established empirical rule which associates stable forward (reverse) S shaped structures low in the corona with positive (negative) helicity. (2) Kink-unstable erupting flux ropes are found to transform a far smaller fraction of their twist helicity into writhe helicity than often assumed. (3) Confined flux rope eruptions tend to show stronger writhe at low heights than ejective eruptions (CMEs). This argues against suggestions that the writhing facilitates the rise of the rope through the overlying field. (4) Erupting filaments which are S shaped already before the eruption and keep the sign of their axis writhe (which is expected if field of one chirality dominates the source volume of the eruption), must reverse their S shape in the course of the rise. Implications for the occurrence of the helical kink instability in such events are discussed.

  18. New approach to diagnosis of pulmonary embolism using multislice CT

    Science.gov (United States)

    Niethammer, Matthias U.; Schoepf, Uwe J.; Wildberger, Hoachim E.; Klotz, Ernst; Fichte, Heinz; Schaller, Stefan

    2001-05-01

    Suspected pulmonary embolism (PE) is a common indication for CT scanning of the thorax. Usually, intravenous contrast agent is administered utilizing a power-injector and the vascular structures are examined for the presence of pulmonary emboli. Current Multi-Slice CT-technology allows extending this morphological analysis by adding a more functional visualization of the actual parenchymal perfusion disturbance. We have developed a new image processing technique which allows selective color encoded display of parenchymal enhancement of the lung, which will be reduced in the presence of PE. Based on thin slice reconstructions an automatic 3D segmentation of the lung is performed followed by threshold based extraction of the major airways and vascular structures. This allows applying an adaptive 3D low-pass filter to the parenchymal volume only. The filtered volume data are then color encoded and overlaid onto the original CT-images. This combination of low-resolution perfusion-weighted color maps and high-resolution gray scale structural data from the same data set greatly enhances visualization of spatial relationships. The resulting images can be displayed in axial, sagittal and coronal orientation. Initial experience indicates that this new technique provides relevant additional information for the clinical management of patients with proven PE. A larger controlled patient study is under way.

  19. Computing Model of the Torque of Magnetic Helical Gear Transmission with Radial Magnetizing Cross Axis%径向磁化交错轴磁性斜齿轮传动力矩的计算模型

    Institute of Scientific and Technical Information of China (English)

    吴克亮

    2012-01-01

    Based on the basic equation of static magnetic field and constitutive relations of magnetic media, the equivalent current model of permanent magnet is deduced. Then a three - dimensional model for computing the torque of radial magnetizing cross axis magnetic helical gear transmission is established by using the equivalent current model. Finally the three - dimensional model is verified by the experimentation. The result shows the three - dimensional model is accurate for torque calculation and is well studied for the parametric analysis and optimal design of this kind of permanent magnetic gear.%根据恒定磁场的基本方程及磁媒质的本构关系,给出了永磁体的等效电流模型.基于该等效电流模型,建立了适用于计算径向磁化交错轴磁性斜齿轮传动机构传动力矩的三维数学模型,并参照实验数据对该模型进行了验证.结果表明建立的传动力矩数学模型是正确的,适用于这种磁性齿轮传动机构的结构参数分析与优化设计.

  20. Helical CT for lumbosacral spinal

    Energy Technology Data Exchange (ETDEWEB)

    Tatsuno, Satoshi; Fukuda, Kunihiko [Jikei Univ., Tokyo (Japan). School of Medicine

    1996-10-01

    The aim of this study was to investigate the efficacy of helical CT for lumbosacral pathology. We performed helical CT with multiplanar reconstruction, including the formation of oblique transaxial and coronal images, in 62 patients with various lumboscral disorders, including 32 non-enhanced CT and 36 CT after myelography. We correlated the appearance of the stenotic spinal canal and neoplastic disease with the findings on MRI obtained at nearly the same time. We obtained helical CT images in all cases in about 30 seconds. The diagnostic ability of helical CT was roughly equal to that of MRI in patients with spondylosis deformans, spondylolisthesis and herniated nucleus pulposus. There was no significant difference in diagnostic value for degenerative lumbosacral disease with canal and foraminal stenosis between non-enhanced and post-myelography helical CT. However, non-enhanced helical CT could not clearly demonstrate neoplastic disease because of the poor contrast resolution. Helical CT was useful in evaluating degenerative disorder and its diagnostic value was nearly equal to that of MRI. We considered that helical CT may be suitable for the assessment of patients with severe lumbago owing to the markedly shortened examination time. However, if helical CT is used as a screening method for lumbosacral disease, one must be careful of its limitations, for example, poor detectability of neoplastic disease, vascular anomalies and so on. (author)

  1. Helicity Transfer in Turbulent Models

    CERN Document Server

    Biferale, L; Toschi, F

    1998-01-01

    Helicity transfer in a shell model of turbulence is investigated. We show that a Reynolds-independent helicity flux is present in the model when the large scale forcing breaks inversion symmetry. The equivalent in Shell Models of the ``2/15 law'', obtained from helicity conservation in Navier-Stokes eqs., is derived and tested. The odd part of helicity flux statistic is found to be dominated by a few very intense events. In a particular model, we calculate analytically leading and sub-leading contribution to the scaling of triple velocity correlation.

  2. Role of multiphasic multi-detector computed tomography (MDCT in the diagnosis and staging of solid neoplastic renal masses

    Directory of Open Access Journals (Sweden)

    Manal H. Wahba

    2015-03-01

    Conclusion: Multiphase multislice computed tomography combined with CT angiography and CT urography have a major role in solid renal neoplastic masses’ diagnosis, characterization and differentiating benign and malignant tumors.

  3. Helicity, topology, and Kelvin waves in reconnecting quantum knots

    Science.gov (United States)

    Clark di Leoni, P.; Mininni, P. D.; Brachet, M. E.

    2016-10-01

    Helicity is a topological invariant that measures the linkage and knottedness of lines, tubes, and ribbons. As such, it has found myriads of applications in astrophysics, fluid dynamics, atmospheric sciences, and biology. In quantum flows, where topology-changing reconnection events are a staple, helicity appears as a key quantity to study. However, the usual definition of helicity is not well posed in quantum vortices, and its computation based on counting links and crossings of centerline vorticity can be downright impossible to apply in complex and turbulent scenarios. We present a definition of helicity which overcomes these problems and which gives the expected result in the large-scale limit. With it, we show that certain reconnection events can excite Kelvin waves and other complex motions of the centerline vorticity, which slowly deplete helicity as they interact nonlinearly, thus linking the theory of vortex knots with observations of quantum fluids. This process also results in the depletion of helicity in a fully turbulent quantum flow, in a way reminiscent of the decay of helicity in classical fluids.

  4. Successive Injection of Opposite Magnetic Helicity in Solar Active Region NOAA 11928

    CERN Document Server

    Vemareddy, P

    2016-01-01

    Understanding the nature and evolution of the photospheric helicity flux transfer is a key to reveal the role of magnetic helicity in coronal dynamics of solar active regions. Using SDO/HMI photospheric vector magnetograms and the derived flow velocity field, we computed boundary driven helicity flux with a 12 minute cadence during the emergence of AR 11928. Accounting the foot point connectivity defined by non-linear force-free magnetic extrapolations, we derived and analyzed the corrected distribution of helicity flux maps. The photospheric helicity flux injection is found to changes sign during the steady emergence of the AR. This reversal is confirmed with the evolution of the photospheric electric currents and with the coronal connectivity as observed in EUV wavelengths with SDO/AIA. During about the three first days of emergence, the AR coronal helicity is positive while later on the field configuration is close to a potential field. As theoretically expected, the magnetic helicity cancelation is associ...

  5. Motion of a helical vortex

    CERN Document Server

    Fuentes, Oscar Velasco

    2015-01-01

    We study the motion of a single helical vortex in an unbounded, inviscid, incompressible fluid. The vortex is an infinite tube whose centerline is a helix and whose cross section is a circle of small radius (compared to the radius of curvature) where the vorticity is uniform and parallel to the centerline. Ever since Joukowsky (1912) deduced that this vortex translates and rotates steadily without change of form, numerous attempts have been made to compute these self-induced velocities. Here we use Hardin's (1982) solution for the velocity field to find new expressions for the vortex's linear and angular velocities. Our results, verified by numerically computing the Helmholtz integral and the Rosenhead-Moore approximation to the Biot-Savart law, are more accurate than previous results over the whole range of values of the vortex pitch and cross-section. We then use the new formulas to study the advection of passive particles near the vortex; we find that the vortex's motion and capacity to transport fluid dep...

  6. Weaving knotted vector fields with tunable helicity

    CERN Document Server

    Kedia, Hridesh; Dennis, Mark R; Irvine, William T M

    2016-01-01

    We present a general construction of divergence-free knotted vector fields from complex scalar fields, whose closed field lines encode many kinds of knots and links, including torus knots, their cables, the figure-8 knot and its generalizations. As finite-energy physical fields they represent initial states for fields such as the magnetic field in a plasma, or the vorticity field in a fluid. We give a systematic procedure for calculating the vector potential, starting from complex scalar functions with knotted zero filaments, thus enabling an explicit computation of the helicity of these knotted fields. The construction can be used to generate isolated knotted flux tubes, filled by knots encoded in the lines of the vector field. Lastly we give examples of manifestly knotted vector fields with vanishing helicity. Our results provide building blocks for analytical models and simulations alike.

  7. Ultra-fast MRI of the human brain with simultaneous multi-slice imaging

    Science.gov (United States)

    Feinberg, David A.; Setsompop, Kawin

    2013-04-01

    The recent advancement of simultaneous multi-slice imaging using multiband excitation has dramatically reduced the scan time of the brain. The evolution of this parallel imaging technique began over a decade ago and through recent sequence improvements has reduced the acquisition time of multi-slice EPI by over ten fold. This technique has recently become extremely useful for (i) functional MRI studies improving the statistical definition of neuronal networks, and (ii) diffusion based fiber tractography to visualize structural connections in the human brain. Several applications and evaluations are underway which show promise for this family of fast imaging sequences.

  8. Extragalactic jets with helical magnetic fields: relativistic MHD simulations

    CERN Document Server

    Keppens, R; van der Holst, B; Casse, F

    2008-01-01

    Extragalactic jets are inferred to harbor dynamically important, organized magnetic fields which presumably aid in the collimation of the relativistic jet flows. We here explore by means of grid-adaptive, high resolution numerical simulations the morphology of AGN jets pervaded by helical field and flow topologies. We concentrate on morphological features of the bow shock and the jet beam behind the Mach disk, for various jet Lorentz factors and magnetic field helicities. We investigate the influence of helical magnetic fields on jet beam propagation in overdense external medium. We use the AMRVAC code, employing a novel hybrid block-based AMR strategy, to compute ideal plasma dynamics in special relativity. The helicity of the beam magnetic field is effectively transported down the beam, with compression zones in between diagonal internal cross-shocks showing stronger toroidal field regions. In comparison with equivalent low-relativistic jets which get surrounded by cocoons with vortical backflows filled by ...

  9. Employing Helicity Amplitudes for Resummation

    NARCIS (Netherlands)

    Moult, I.; Stewart, I.W.; Tackmann, F.J.; Waalewijn, W.J.

    2015-01-01

    Many state-of-the-art QCD calculations for multileg processes use helicity amplitudes as their fundamental ingredients. We construct a simple and easy-to-use helicity operator basis in soft-collinear effective theory (SCET), for which the hard Wilson coefficients from matching QCD onto SCET are dire

  10. Quark Helicity and Transversity Distributions

    CERN Document Server

    Hwang, Dae Sung

    2016-01-01

    The quark transversity distribution inside nucleon is less understood than the quark unpolarized and helicity distributions inside nucleon. In particular, it is important to know clearly why the quark helicity and transversity distributions are different. We investigate the origin of their discrepancy.

  11. Towards real-time thermometry using simultaneous multislice MRI

    Science.gov (United States)

    Borman, P. T. S.; Bos, C.; de Boorder, T.; Raaymakers, B. W.; Moonen, C. T. W.; Crijns, S. P. M.

    2016-09-01

    MR-guided thermal therapies, such as high-intensity focused ultrasound (MRgHIFU) and laser-induced thermal therapy (MRgLITT) are increasingly being applied in oncology and neurology. MRI is used for guidance since it can measure temperature noninvasively based on the proton resonance frequency shift (PRFS). For therapy guidance using PRFS thermometry, high temporal resolution and large spatial coverage are desirable. We propose to use the parallel imaging technique simultaneous multislice (SMS) in combination with controlled aliasing (CAIPIRINHA) to accelerate the acquisition. We compare this with the sensitivity encoding (SENSE) acceleration technique. Two experiments were performed to validate that SMS can be used to increase the spatial coverage or the temporal resolution. The first was performed in agar gel using LITT heating and a gradient-echo sequence with echo-planar imaging (EPI), and the second was performed in bovine muscle using HIFU heating and a gradient-echo sequence without EPI. In both experiments temperature curves from an unaccelerated scan and from SMS, SENSE, and SENSE/SMS accelerated scans were compared. The precision was quantified by a standard deviation analysis of scans without heating. Both experiments showed a good agreement between the temperature curves obtained from the unaccelerated, and SMS accelerated scans, confirming that accuracy was maintained during SMS acceleration. The standard deviations of the temperature measurements obtained with SMS were significantly smaller than when SENSE was used, implying that SMS allows for higher acceleration. In the LITT and HIFU experiments SMS factors up to 4 and 3 were reached, respectively, with a loss of precision of less than a factor of 3. Based on these results we conclude that SMS acceleration of PRFS thermometry is a valuable addition to SENSE, because it allows for a higher temporal resolution or bigger spatial coverage, with a higher precision.

  12. MEGACELL: A nanocrystal model construction software for HRTEM multislice simulation

    Energy Technology Data Exchange (ETDEWEB)

    Stroppa, Daniel G., E-mail: dstroppa@lnls.br [Brazilian Synchrotron Light Laboratory, 13083-970 Campinas, SP (Brazil); Mechanical Engineering School, University of Campinas, 13083-860 Campinas, SP (Brazil); Righetto, Ricardo D. [Brazilian Synchrotron Light Laboratory, 13083-970 Campinas, SP (Brazil); School of Electrical and Computer Engineering, University of Campinas, 13083-852 Campinas, SP (Brazil); Montoro, Luciano A. [Brazilian Synchrotron Light Laboratory, 13083-970 Campinas, SP (Brazil); Ramirez, Antonio J. [Brazilian Synchrotron Light Laboratory, 13083-970 Campinas, SP (Brazil); Mechanical Engineering School, University of Campinas, 13083-860 Campinas, SP (Brazil)

    2011-07-15

    Image simulation has an invaluable importance for the accurate analysis of High Resolution Transmission Electron Microscope (HRTEM) results, especially due to its non-linear image formation mechanism. Because the as-obtained images cannot be interpreted in a straightforward fashion, the retrieval of both qualitative and quantitative information from HRTEM micrographs requires an iterative process including the simulation of a nanocrystal model and its comparison with experimental images. However most of the available image simulation software requires atom-by-atom coordinates as input for the calculations, which can be prohibitive for large finite crystals and/or low-symmetry systems and zone axis orientations. This paper presents an open source citation-ware tool named MEGACELL, which was developed to assist on the construction of nanocrystals models. It allows the user to build nanocrystals with virtually any convex polyhedral geometry and to retrieve its atomic positions either as a plain text file or as an output compatible with EMS (Electron Microscopy Software) input protocol. In addition to the description of this tool features, some construction examples and its application for scientific studies are presented. These studies show MEGACELL as a handy tool, which allows an easier construction of complex nanocrystal models and improves the quantitative information extraction from HRTEM images. -- Highlights: {yields} A software to support the HRTEM image simulation of nanocrystals in actual size. {yields} MEGACELL allows the construction of complex nanocrystals models for multislice image simulation. {yields} Some examples of improved nanocrystalline system characterization are presented, including the analysis of 3D morphology and growth behavior.

  13. Magnetic design constraints of helical solenoids

    Energy Technology Data Exchange (ETDEWEB)

    Lopes, M. L. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Krave, S. T. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Tompkins, J. C. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Yonehara, K. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Flanagan, G. [Muons Inc., Batavia, IL (United States); Kahn, S. A. [Muons Inc., Batavia, IL (United States); Melconian, K. [Texas A & M Univ., College Station, TX (United States)

    2015-01-30

    Helical solenoids have been proposed as an option for a Helical Cooling Channel for muons in a proposed Muon Collider. Helical solenoids can provide the required three main field components: solenoidal, helical dipole, and a helical gradient. In general terms, the last two are a function of many geometric parameters: coil aperture, coil radial and longitudinal dimensions, helix period and orbit radius. In this paper, we present design studies of a Helical Solenoid, addressing the geometric tunability limits and auxiliary correction system.

  14. The Advanced Helical Generator

    Energy Technology Data Exchange (ETDEWEB)

    Reisman, D B; Javedani, J B; Ellsworth, G F; Kuklo, R M; Goerz, D A; White, A D; Tallerico, L J; Gidding, D A; Murphy, M J; Chase, J B

    2009-10-26

    A high explosive pulsed power (HEPP) generator called the Advanced Helical Generator (AHG) has been designed, built, and successfully tested. The AHG incorporates design principles of voltage and current management to obtain a high current and energy gain. Its design was facilitated by the use of modern modeling tools as well as high precision manufacture. The result was a first-shot success. The AHG delivered 16 Mega-Amperes of current and 11 Mega-Joules of energy to a quasi-static 80 nH inductive load. A current gain of 154 times was obtained with a peak exponential rise time of 20 {micro}s. We will describe in detail the design and testing of the AHG.

  15. Helicity dependent parton distributions

    CERN Document Server

    Scopetta, Sergio; 10.4249/scholarpedia.10226

    2011-01-01

    The helicity dependent parton distributions describe the number density of partons with given longitudinal momentum x and given polarization in a hadron polarized longitudinally with respect to its motion. After the discovery, more than 70 years ago, that the proton is not elementary, the observation of Bjorken scaling in the late 1960s lead to the idea of hadrons containing almost pointlike constituents, the partons. Since then, Deep Inelastic Scattering (DIS) has played a crucial role in our understanding of hadron structure. Through DIS experiments it has been possible to link the partons to the quarks, and to unveil the presence of other pointlike constituents, the gluons, which lead into a dynamical theory of quarks and gluons - quantum chromodynamics (QCD). Polarized DIS, i.e. the collision of a longitudinally polarized lepton beam on a polarized target (either longitudinally or transversely polarized), provides a complementary information regarding the structure of the nucleon. Whereas ordinary DIS pro...

  16. First experiences from Copenhagen with paediatric single photon emission computed tomography/computed tomography

    DEFF Research Database (Denmark)

    Mortensen, Jann; Bech, Birthe Højlund; Højgaard, Liselotte

    2011-01-01

    OBJECTIVE: This study evaluates the diagnostic value of single photon emission computed tomographic (SPECT)/multislice computed tomographic (MSCT) fusion images compared with planar scintigraphy in children. METHODS: Fifteen children [eight girls, mean age 13 years (range 2-17 years)] who were...

  17. Assessment of multislice CT to quantify pulmonary emphysema function and physiology in a rat model

    Science.gov (United States)

    Cao, Minsong; Stantz, Keith M.; Liang, Yun; Krishnamurthi, Ganapathy; Presson, Robert G., Jr.

    2005-04-01

    Purpose: The purpose of this study is to evaluate multi-slice computed tomography technology to quantify functional and physiologic changes in rats with pulmonary emphysema. Method: Seven rats were scanned using a 16-slice CT (Philips MX8000 IDT) before and after artificial inducement of emphysema. Functional parameters i.e. lung volumes were measured by non-contrast spiral scan during forced breath-hold at inspiration and expiration followed by image segmentation based on attenuation threshold. Dynamic CT imaging was performed immediately following the contrast injection to estimate physiology changes. Pulmonary perfusion, fractional blood volume, and mean transit times (MTTs) were estimated by fitting the time-density curves of contrast material using a compartmental model. Results: The preliminary results indicated that the lung volumes of emphysema rats increased by 3.52+/-1.70mL (plung densities of emphysema rats decreased by 91.76+/-68.11HU (pperfusion for normal and emphysema rats were 0.25+/-0.04ml/s/ml and 0.32+/-0.09ml/s/ml respectively. The fractional blood volumes for normal and emphysema rats were 0.21+/-0.04 and 0.15+/-0.02. There was a trend toward faster MTTs for emphysema rats (0.42+/-0.08s) than normal rats (0.89+/-0.19s) with p<0.006, suggesting that blood flow crossing the capillaries increases as the capillary volume decreases and which may cause the red blood cells to leave the capillaries incompletely saturated with oxygen if the MTTs become too short. Conclusion: Quantitative measurement using CT of structural and functional changes in pulmonary emphysema appears promising for small animals.

  18. Postoperative monitoring of distal intraarticular radial fractures treated with osteosynthesis by means of multislice CT

    Energy Technology Data Exchange (ETDEWEB)

    Lorenzen, M.; Wedegaertner, U.; Weber, C.; Adam, G.; Lorenzen, J. [Universitaetsklinik Hamburg-Eppendorf (Germany). Abt. fuer Radiologie

    2011-02-15

    Purpose: This study evaluates multislice CT (MSCT) for the postsurgical control of intraarticular fractures of the distal radius. Materials and Methods: In 131 patients conventional X-rays in two planes and MSCT were performed. In a consensus process two experienced radiologists judged conventional X-ray and computed tomography images in a random view. The correct position of the osteosynthetic material was assessed and it was ascertained whether an articular surface incongruity, a gap between two fracture fragments, or an intraarticular bone element was detectable. For each point of evaluation a confidence level of the evaluation was assessed on a five-point scale. Results: Ninety patients were classified as having correct alignment and osteosynthesis according to conventional X-ray, while when using the findings from axial CT scans only, 82 patients, and after the addition of multiplanar re-constructions (MPR) only 73 patients were found to have almost proper alignment and osteosynthesis. In 42 patients dehiscence of the fragments was diagnosed with MSCT, but was not visualized by X-ray, leading to surgical revision in eight patients, confirming the diagnosis. In five patients an intraarticular position of intraarticular material was confirmed with MSCT and surgical revision. A significant advantage for the evaluation confidence level was achieved for MPRs in comparison with axial CT scans and X-ray. Conclusion: The marked diagnostic advantage with a high evaluation confidence level in comparison with conventional X-ray methods justify the use of MSCT during postoperative monitoring of articular radial fractures treated with osteosynthesis. (orig.)

  19. 多层CT小肠造影与单气囊小肠镜对小肠梗阻的诊断价值%Diagnostic value of multi-slice computed tomography enterography before single balloon enteroscopy for small bowel obstruction

    Institute of Scientific and Technical Information of China (English)

    李娜; 赵晓军; 王海红; 王昕; 李爱琴; 谢惠; 余东亮; 韩英; 盛剑秋

    2013-01-01

    目的 探讨多层CT小肠造影(MSCTE)与单气囊小肠镜(SBE)在小肠梗阻性病变的诊断价值.方法 收集2009年6月-2013年2月临床和/或腹部X线平片疑为小肠梗阻的患者30例.所有患者先行MSCTE检查,根据检查结果选择经口或经肛SBE检查.分析两种检查方法对小肠梗阻性病变的诊断率.结果 ①MSCTE检查诊断小肠梗阻的灵敏度为85.19%,特异度为66.67%,阳性预测值为95.83%,阴性预测值为33.33%.SBE检查分别为81.48%、100%、100%和37.50%.②MSCTE和SBE检出病变一致性为53.33% (16/30).③根据MSCTE检查结果选择经口或经肛SBE检查,MSCTE检查阳性指导SBE选择进镜方式正确率高于MSCTE检查阴性(95.83% vs 33.33%,P<0.05).结论 MSCTE和SBE对小肠梗阻的诊断率相当,二者联合应用可提高对小肠梗阻性病变的诊断率.MSCTE检查结果可以指导SBE选择进镜方式.%Objective To evaluate the diagnostic value of multi-slice CT enterography (MSCTE) before single balloon enteroscopy (SBE) for patients with small bowel obstruction (SBO).Methods 30 patients with MSCTE before SBE for SBO were collected prospectively from Jun.2009 to Feb.2013.The clinical impact of MSCTE on the subsequent SBE examinations and the diagnostic yields of both MSCTE and SBE were evaluated respectively.Results ① In detecting SBO,MSCTE had a sensitivity of 85.19%,a specificity of 66.67%,a positive predictive value of 95.83%,and a negative predictive value of 33.33%.SBE had a sensitivity of 81.48%,a specificity of 100%,a positive predictive value of 100%,and a negative predictive value of 37.5%.② The consistency was 53.33%.③ The choice of initial route of SBE was correct in those with a positive MSCTE vs negative MSCTE (95.83% vs 33.33 %,P <0.05).Conclusion MSCTE and SBE are nearly equal in their ability to detect SBO.The combined application of two methods can improve the diagnosis rate of SBO.This study suggests MSCTE

  20. The high-grade interpolator: a means for enhancing the resolution of helical computed tomography images of the lung; El interpolador de alto orden: un medio para incrementar la resolucion de las iamgenes pulmonares obtenidas mediante tomografia computarizada espiral

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Santos, J. M.; Torres del rio, S.; Blanco, A.; Rodriguez, R.; Parlorio, E.; Garcia, A.; Girela, E.; Hernandez, M. D. [Hospital Universitario J. M. Morales Mesequer. Murcia (Spain); Canteras, M. [Universidad de Murcia (Spain)

    2002-07-01

    The purpose of this study was to demonstrate that the use of a high-grade interpolator in the reconstruction of images of the chest increases the resolution, independently of the high-resolution filter. Eight independent observers in two groups (experts and non experts) assessed (two readings separated by a time interval) the same section of the chest reconstructed four times (st-st, st-xs, b-st, b-xs), combining standard (st) and high-resolution (b) filters and standard (st) and high-grade (xs) interpolators. The images were classified from greater to lesser in terms of the resolution perceived. The results were used to compare the degree of resolution introduced by the interpolator and the filter and to determine whether or not there existed variability between observers and between the observations of each, and whether experience played a role in the findings. Six of the eight observers assigned the b-xs images the highest degree of resolution in the majority of cases, followed by the b-st image, the st-xs image and, finally, the st-st image. The other tow observers (one expert and one nonexpert) different only with respect to the order of the st-xs and b-st images, which they assigned the second and third places, respectively. The expert group showed no intra observer variability, while two of the nonexpert observers did. The high-grade interpolator enhances the resolution of images of the chest regardless of who evaluates them, while it does not substantially increase image noise. Thus, its use is recommended in helical computed tomography imaging of the lung. (Author) 10 refs.

  1. Passive scalars: mixing, diffusion and intermittency in helical and non-helical rotating turbulence

    CERN Document Server

    Imazio, P Rodriguez

    2015-01-01

    We use direct numerical simulations to compute structure functions, scaling exponents, probability density functions and turbulent transport coefficients of passive scalars in turbulent rotating helical and non-helical flows. We show that helicity affects the inertial range scaling of the velocity and of the passive scalar when rotation is present, with a spectral law consistent with $\\sim k_{\\perp}^{-1.4}$ for the passive scalar variance spectrum. This scaling law is consistent with the phenomenological argument presented in \\cite{imazio2011} for rotating non-helical flows, wich states that if energy follows a $E(k)\\sim k^{-n}$ law, then the passive scalar variance follows a law $V(k) \\sim k^{-n_{\\theta}}$ with $n_{\\theta}=(5-n)/2$. With the second order scaling exponent obtained from this law, and using the Kraichnan model, we obtain anomalous scaling exponents for the passive scalar that are in good agreement with the numerical results. Intermittency of the passive scalar is found to be stronger than in th...

  2. Differential geometry of proteins. Helical approximations.

    Science.gov (United States)

    Louie, A H; Somorjai, R L

    1983-07-25

    We regard a protein molecule as a geometric object, and in a first approximation represent it as a regular parametrized space curve passing through its alpha-carbon atoms (the backbone). In an earlier paper we argued that the regular patterns of secondary structures of proteins (morphons) correspond to geodesics on minimal surfaces. In this paper we discuss methods of recognizing these morphons on space curves that represent the protein backbone conformation. The mathematical tool we employ is the differential geometry of curves and surfaces. We introduce a natural approximation of backbone space curves in terms of helical approximating elements and present a computer algorithm to implement the approximation. Simple recognition criteria are given for the various morphons of proteins. These are incorporated into our helical approximation algorithm, together with more non-local criteria for the recognition of beta-sheet topologies. The method and the algorithm are illustrated with several examples of representative proteins. Generalizations of the helical approximation method are considered and their possible implications for protein energetics are sketched.

  3. Validities of three multislice algorithms for quantitative low-energy transmission electron microscopy.

    Science.gov (United States)

    Ming, W Q; Chen, J H

    2013-11-01

    Three different types of multislice algorithms, namely the conventional multislice (CMS) algorithm, the propagator-corrected multislice (PCMS) algorithm and the fully-corrected multislice (FCMS) algorithm, have been evaluated in comparison with respect to the accelerating voltages in transmission electron microscopy. Detailed numerical calculations have been performed to test their validities. The results show that the three algorithms are equivalent for accelerating voltage above 100kV. However, below 100 kV, the CMS algorithm will introduce significant errors, not only for higher-order Laue zone (HOLZ) reflections but also for zero-order Laue zone (ZOLZ) reflections. The differences between the PCMS and FCMS algorithms are negligible and mainly appear in HOLZ reflections. Nonetheless, when the accelerating voltage is further lowered to 20 kV or below, the PCMS algorithm will also yield results deviating from the FCMS results. The present study demonstrates that the propagation of the electron wave from one slice to the next slice is actually cross-correlated with the crystal potential in a complex manner, such that when the accelerating voltage is lowered to 10 kV, the accuracy of the algorithms is dependent of the scattering power of the specimen. © 2013 Elsevier B.V. All rights reserved.

  4. Turbulent Dynamos and Magnetic Helicity

    Energy Technology Data Exchange (ETDEWEB)

    Ji, Hantao

    1999-04-01

    It is shown that the turbulent dynamo alpha-effect converts magnetic helicity from the turbulent field to the mean field when the turbulence is electromagnetic while the magnetic helicity of the mean-field is transported across space when the turbulence is elcetrostatic or due to the elcetron diamagnetic effect. In all cases, however, the dynamo effect strictly conserves the total helicity expect for a battery effect which vanishes in the limit of magnetohydrodynamics. Implications for astrophysical situations, especially for the solar dynamo, are discussed.

  5. SPring-8 twin helical undulator.

    Science.gov (United States)

    Hara, T; Tanaka, T; Tanabe, T; Maréchal, X M; Kumagai, K; Kitamura, H

    1998-05-01

    There are several ways of producing circularly polarized light, such as using asymmetric devices, crossed undulators etc. The SPring-8 helical undulator introduces a simple way of producing both horizontal and vertical fields in one undulator. All the magnet arrays are arranged above and below the plane of the electron orbit, so there is no limitation of access from the sides of the undulator. For the SPring-8 BL25SU, two helical undulators will be installed in tandem, and the helicity of the polarization can be switched at up to 10 Hz using five kicker magnets.

  6. Assessment Of Coronary Arterial Stents By Multislice-CT Angiography

    Energy Technology Data Exchange (ETDEWEB)

    Maintz, D.; Fallenberg, E. M.; Heindel, W.; Fischbach, R. [Univ. of Muenster (Germany). Dept. of Clinical Radiology; Grude, M. [Univ. of Muenster (Germany). Dept. of Cardiology and Angiology

    2003-11-01

    Purpose: To assess patency and lumen visibility of coronary artery stents by multislice-CT angiography (MSCTA) in comparison with conventional coronary angiography as the standard of reference. Material and Methods: 47 stents of 13 different types were evaluated in 29 patients. MSCTA was performed on a 4-slice scanner with a standard coronary protocol (detector collimation 4 x 1 mm; table feed 1.5 mm/rotation, 400 mAs, 120 kV). Image evaluation was performed by two readers who were blinded to the reports from the catheter angiography. MIP reconstructions were evaluated for image quality on a 4-point scale (1 = poor, 4 = excellent) and stent patency (contrast distal to the stent as an indirect patency sign). Axial images and multiplanar reformations through the stents were used for assessment of stent lumen visibility (measurement of the visible stent lumen diameter) and detection of relevant in-stent stenosis (50%). Results: Image quality was fair to good on average (score 2.64 {+-} 1.0) and depended on the heart rate (heart rate 45-60: average score 3.2, heart rate 61-70: average score 2.8, heart rate >71: average score 1.4). Thirty-seven stents were correctly classified as patent, 1 was correctly classified as occluded and 9 stents were not assessable due to insufficient image quality because of triggering artifacts. Parts of the stent lumen could be visualized in 30 cases. On average, 20-40% of the stent lumen diameter was visible. Twenty-five stents were correctly classified as having no stenosis, 1 was falsely classified as stenosed, 1 was correctly classified as occluded. In 20 stents lumen visibility was not sufficient for stenosis evaluation. Conclusion: Although the stent lumen may be partly visualized in most stents, a reliable evaluation of in-stent stenoses does not seem practical by 4-slice MSCT. Nevertheless, for stent patency evaluation, MS-CTA might provide valuable clinical information. With submillimeter MSCT (e.g. 16-slice scanners) and more

  7. Magnetic helicity and energy spectra of a solar active region

    CERN Document Server

    Zhang, Hongqi; Sokoloff, D D

    2013-01-01

    We compute magnetic helicity and energy spectra of the solar active region NOAA 11158 during 11-15 February 2011 at 20 degr southern heliographic latitude using observational photospheric vector magnetograms. We adopt the isotropic representation of the Fourier-transformed two-point correlation tensor of the magnetic field. The sign of magnetic helicity turns out to be predominantly positive at all wavenumbers. This sign is consistent with what is theoretically expected for the southern hemisphere. The relative magnetic helicity is around 8% and strongest at intermediate wavenumbers of k ~ 0.4 Mm^{-1}, corresponding to a scale of 2 pi/k ~ 16 Mm. The same sign and a somewhat smaller value is also found for the relative current helicity evaluated in real space based on the vertical components of magnetic field and current density. The current helicity spectrum is estimated from the magnetic helicity spectrum and its modulus shows a k^{-5/3} spectrum at large wavenumbers. A similar power law is also obtained for...

  8. Decay of helical and non-helical magnetic knots

    CERN Document Server

    Candelaresi, Simon

    2011-01-01

    We present calculations of the relaxation of magnetic field structures that have the shape of particular knots and links. A set of helical magnetic flux configurations is considered, which we call $n$-foil knots of which the trefoil knot is the most primitive member. We also consider two non-helical knots, namely the Borromean rings as well as a single interlocked flux rope that also serves as the logo of the Inter-University Centre for Astronomy and Astrophysics in Pune, India. The field decay characteristics of both configurations is investigated and compared with previous calculations of helical and non-helical triple ring configurations. For the $n$-foil knots the decay is described by power laws that range form $t^{-2/3}$ to $t^{-1/3}$, which can be as slow as the $t^{-1/3}$ behavior for helical triple-ring structures that was seen in earlier work. The two non-helical configurations decay like $t^{-1}$, which is somewhat slower than the previously obtained $t^{-3/2}$ behavior in the decay of interlocked ...

  9. Magnetic Helicity and Planetary Dynamos

    Science.gov (United States)

    Shebalin, John V.

    2012-01-01

    A model planetary dynamo based on the Boussinesq approximation along with homogeneous boundary conditions is considered. A statistical theory describing a large-scale MHD dynamo is found, in which magnetic helicity is the critical parameter

  10. Asymmetric catalysis with helical polymers

    NARCIS (Netherlands)

    Megens, Rik P.; Roelfes, Gerard

    Inspired by nature, the use of helical biopolymer catalysts has emerged over the last years as a new approach to asymmetric catalysis. In this Concept article the various approaches and designs and their application in asymmetric catalysis will be discussed.

  11. Asymmetric catalysis with helical polymers

    NARCIS (Netherlands)

    Megens, Rik P.; Roelfes, Gerard

    2011-01-01

    Inspired by nature, the use of helical biopolymer catalysts has emerged over the last years as a new approach to asymmetric catalysis. In this Concept article the various approaches and designs and their application in asymmetric catalysis will be discussed.

  12. Modeling helicity dissipation-rate equation

    CERN Document Server

    Yokoi, Nobumitsu

    2016-01-01

    Transport equation of the dissipation rate of turbulent helicity is derived with the aid of a statistical analytical closure theory of inhomogeneous turbulence. It is shown that an assumption on the helicity scaling with an algebraic relationship between the helicity and its dissipation rate leads to the transport equation of the turbulent helicity dissipation rate without resorting to a heuristic modeling.

  13. Holographic Metals and Insulators with Helical Symmetry

    CERN Document Server

    Donos, Aristomenis; Kiritsis, Elias

    2014-01-01

    Homogeneous, zero temperature scaling solutions with Bianchi VII spatial geometry are constructed in Einstein-Maxwell-Dilaton theory. They correspond to quantum critical saddle points with helical symmetry at finite density. Assuming $AdS_{5}$ UV asymptotics, the small frequency/(temperature) dependence of the AC/(DC) electric conductivity along the director of the helix are computed. A large class of insulating and conducting anisotropic phases is found, as well as isotropic, metallic phases. Conduction can be dominated by dissipation due to weak breaking of translation symmetry or by a quantum critical current.

  14. Tokamak magnetohydrodynamic equilibrium states with axisymmetric boundary and a 3D helical core.

    Science.gov (United States)

    Cooper, W A; Graves, J P; Pochelon, A; Sauter, O; Villard, L

    2010-07-16

    Magnetohydrodynamic (MHD) equilibrium states with imposed axisymmetric boundary are computed in which a spontaneous bifurcation develops to produce an internal three-dimensional (3D) configuration with a helical structure in addition to the standard axisymmetric system. Equilibrium states with similar MHD energy levels are shown to develop very different geometric structures. The helical equilibrium states resemble saturated internal kink mode structures.

  15. Twist, writhe and energy from the helicity of magnetic perturbed vortex filaments

    OpenAIRE

    de Andrade, Luiz Carlos Garcia

    2007-01-01

    The twist and writhe numbers and magnetic energy of an orthogonally perturbed vortex filaments are obtained from the computation of the magnetic helicity of geodesic and abnormal magnetohydrodynamical (MHD) vortex filament solutions. Twist is computed from a formula recently derived by Berger and Prior [J. Phys. A 39 (2006) 8321] and finally writhe is computed from the theorem that the helicity is proportional to the sum of twist and writhe. The writhe number is proportional to the total tors...

  16. The next large helical devices

    Science.gov (United States)

    Iiyoshi, Atsuo; Yamazaki, Kozo

    1995-06-01

    Helical systems have the strong advantage of inherent steady-state operation for fusion reactors. Two large helical devices with fully superconducting coil systems are presently under design and construction. One is the LHD (Large Helical Device) [Fusion Technol. 17, 169 (1990)] with major radius=3.9 m and magnetic field=3-4 T, that is under construction during 1990-1997 at NIFS (National Institute for Fusion Science), Nagoya/Toki, Japan; it features continuous helical coils and a clean helical divertor focusing on edge configuration optimization. The other one in the W7-X (Wendelstein 7-X) [in Plasma Physics and Controlled Fusion Nuclear Research, 1990, (International Atomic Energy Agency, Vienna, 1991), Vol. 3, p. 525] with major radius=5.5 m and magnetic field=3 T, that is under review at IPP (Max-Planck Institute for Plasma Physics), Garching, Germany; it has adopted a modular coil system after elaborate optimization studies. These two programs are complementary in promoting world helical fusion research and in extending the understanding of toroidal plasmas through comparisons with large tokamaks.

  17. omega-Helices in proteins.

    Science.gov (United States)

    Enkhbayar, Purevjav; Boldgiv, Bazartseren; Matsushima, Norio

    2010-05-01

    A modification of the alpha-helix, termed the omega-helix, has four residues in one turn of a helix. We searched the omega-helix in proteins by the HELFIT program which determines the helical parameters-pitch, residues per turn, radius, and handedness-and p = rmsd/(N - 1)(1/2) estimating helical regularity, where "rmsd" is the root mean square deviation from the best fit helix and "N" is helix length. A total of 1,496 regular alpha-helices 6-9 residues long with p < or = 0.10 A were identified from 866 protein chains. The statistical analysis provides a strong evidence that the frequency distribution of helices versus n indicates the bimodality of typical alpha-helix and omega-helix. Sixty-two right handed omega-helices identified (7.2% of proteins) show non-planarity of the peptide groups. There is amino acid preference of Asp and Cys. These observations and analyses insist that the omega-helices occur really in proteins.

  18. Employing Helicity Amplitudes for Resummation

    CERN Document Server

    Moult, Ian; Tackmann, Frank J; Waalewijn, Wouter J

    2015-01-01

    Many state-of-the-art QCD calculations for multileg processes use helicity amplitudes as their fundamental ingredients. We construct a simple and easy-to-use helicity operator basis in soft-collinear effective theory (SCET), for which the hard Wilson coefficients from matching QCD onto SCET are directly given in terms of color-ordered helicity amplitudes. Using this basis allows one to seamlessly combine fixed-order helicity amplitudes at any order they are known with a resummation of higher-order logarithmic corrections. In particular, the virtual loop amplitudes can be employed in factorization theorems to make predictions for exclusive jet cross sections without the use of numerical subtraction schemes to handle real-virtual infrared cancellations. We also discuss matching onto SCET in renormalization schemes with helicities in $4$- and $d$-dimensions. To demonstrate that our helicity operator basis is easy to use, we provide an explicit construction of the operator basis, as well as results for the hard m...

  19. Distributed Computing on Gadgetron: A new paradigm for MRI reconstruction

    DEFF Research Database (Denmark)

    Xue, Hui; Kelmann, Peter; Inati, Souheil

    cloud computing. With this extension (named GT-Plus), any number of Gadgetron processes can run cooperatively across multiple computers. GT-Plus framework was deployed on Amazon EC2 cloud and NIH’s Biowulf system. We demonstrate that with the GT-Plus cloud, a multi-slice free-breathing myocardial cine...

  20. Distributed Computing on Gadgetron: A new paradigm for MRI reconstruction

    DEFF Research Database (Denmark)

    Xue, Hui; Kelmann, Peter; Inati, Souheil

    cloud computing. With this extension (named GT-Plus), any number of Gadgetron processes can run cooperatively across multiple computers. GT-Plus framework was deployed on Amazon EC2 cloud and NIH’s Biowulf system. We demonstrate that with the GT-Plus cloud, a multi-slice free-breathing myocardial cine...

  1. CMB anisotropies generated by a stochastic background of primordial magnetic fields with non-zero helicity

    Science.gov (United States)

    Ballardini, Mario; Finelli, Fabio; Paoletti, Daniela

    2015-10-01

    We consider the impact of a stochastic background of primordial magnetic fields with non-vanishing helicity on CMB anisotropies in temperature and polarization. We compute the exact expressions for the scalar, vector and tensor part of the energy-momentum tensor including the helical contribution, by assuming a power-law dependence for the spectra and a comoving cutoff which mimics the damping due to viscosity. We also compute the parity-odd correlator between the helical and non-helical contribution which generate the TB and EB cross-correlation in the CMB pattern. We finally show the impact of including the helical term on the power spectra of CMB anisotropies up to multipoles with l ~ Script O(103).

  2. CMB anisotropies generated by a stochastic background of primordial magnetic fields with non-zero helicity

    CERN Document Server

    Ballardini, Mario; Paoletti, Daniela

    2014-01-01

    We consider the impact of a stochastic background of primordial magnetic fields with non-vanishing helicity on CMB anisotropies in temperature and polarization. We compute the exact expressions for the scalar, vector and tensor part of the energy-momentum tensor including the helical contribution, by assuming a power-law dependence for the spectra and a comoving cutoff which mimics the damping due to viscosity. We also compute the parity-odd correlator between the helical and non-helical contribution which generate the TB and EB cross-correlation in the CMB pattern. We finally show the impact of including the helical term on the power spectra of CMB anisotropies up to multipoles with ell ~ O(10^3)$.

  3. First observational application of a connectivity--based helicity flux density

    CERN Document Server

    Dalmasse, K; Valori, G; Démoulin, P; Green, L M

    2013-01-01

    Measuring the magnetic helicity distribution in the solar corona can help in understanding the trigger of solar eruptive events because magnetic helicity is believed to play a key role in solar activity due to its conservation property. A new method for computing the photospheric distribution of the helicity flux was recently developed. This method takes into account the magnetic field connectivity whereas previous methods were based on photospheric signatures only. This novel method maps the true injection of magnetic helicity in active regions. We applied this method for the first time to an observed active region, NOAA 11158, which was the source of intense flaring activity. We used high-resolution vector magnetograms from the SDO/HMI instrument to compute the photospheric flux transport velocities and to perform a nonlinear force-free magnetic field extrapolation. We determined and compared the magnetic helicity flux distribution using a purely photospheric as well as a connectivity-based method. While th...

  4. All Non-Maximally-Helicity-Violating One-Loop Seven-Gluon Amplitudes in N=4 Super-Yang-Mills Theory

    CERN Document Server

    Bern, Z; Dixon, L J; Kosower, D A; Bern, Zvi; Duca, Vittorio Del; Dixon, Lance J.; Kosower, David A.

    2004-01-01

    We compute the non-MHV one-loop seven-gluon amplitudes in N=4 super-Yang-Mills theory, which contain three negative-helicity gluons and four positive-helicity gluons. There are four independent color-ordered amplitudes, (- - - + + + +), (- - + - + + +), (- - + + -+ +) and (- + - + - + +). The MHV amplitudes containing two negative-helicity and five positive-helicity gluons were computed previously, so all independent one-loop seven-gluon helicity amplitudes are now known for this theory. We present partial information about an infinite sequence of next-to-MHV one-loop helicity amplitudes, with three negative-helicity and n-3 positive-helicity gluons, and the color ordering (- - - + + ... + +); we give a new coefficient of one class of integral functions entering this amplitude. We discuss the twistor-space properties of the box-integral-function coefficients in the amplitudes, which are quite simple and suggestive.

  5. The Non-Maximally-Helicity-Violating One-Loop Seven-Gluon Amplitudes in N=4 Super-Yang-Mills Theory

    Energy Technology Data Exchange (ETDEWEB)

    Bern, Z.

    2004-10-22

    We compute the non-MHV one-loop seven-gluon amplitudes in N = 4 super-Yang-Mills theory, which contain three negative-helicity gluons and four positive-helicity gluons. There are four independent color-ordered amplitudes, (---++++), (--+-+++), (--++-++) and (-+-+-++). The MHV amplitudes containing two negative-helicity and five positive-helicity gluons were computed previously, so all independent one-loop seven-gluon helicity amplitudes are now known for this theory. We present partial information about an infinite sequence of next-to-MHV one-loop helicity amplitudes, with three negative-helicity and n - 3 positive-helicity gluons, and the color ordering (---+{center_dot}{center_dot}{center_dot}++); we give a new coefficient of one class of integral functions entering this amplitude. We discuss the twistor-space properties of the box-integral-function coefficients in the amplitudes, which are quite simple and suggestive.

  6. Equilibrium reconstruction for Single Helical Axis reversed field pinch plasmas

    CERN Document Server

    Martines, Emilio; Momo, Barbara; Terranova, David; Zanca, Paolo; Alfier, Alberto; Bonomo, Federica; Canton, Alessandra; Fassina, Alessandro; Franz, Paolo; Innocente, Paolo

    2011-01-01

    Single Helical Axis (SHAx) configurations are emerging as the natural state for high current reversed field pinch (RFP) plasmas. These states feature the presence of transport barriers in the core plasma. Here we present a method for computing the equilibrium magnetic surfaces for these states in the force-free approximation, which has been implemented in the SHEq code. The method is based on the superposition of a zeroth order axisymmetric equilibrium and of a first order helical perturbation computed according to Newcomb's equation supplemented with edge magnetic field measurements. The mapping of the measured electron temperature profiles, soft X-ray emission and interferometric density measurements on the computed magnetic surfaces demonstrates the quality of the equilibrium reconstruction. The procedure for computing flux surface averages is illustrated, and applied to the evaluation of the thermal conductivity profile. The consistency of the evaluated equilibria with Ohm's law is also discussed.

  7. Equilibrium reconstruction for single helical axis reversed field pinch plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Martines, E; Lorenzini, R; Momo, B; Terranova, D; Zanca, P; Alfier, A; Bonomo, F; Canton, A; Fassina, A; Franz, P; Innocente, P, E-mail: emilio.martines@igi.cnr.it [Consorzio RFX, Associazione Euratom-ENEA sulla Fusione, corso Stati Uniti 4, 35127 Padova (Italy)

    2011-03-15

    Single helical axis configurations are emerging as the natural state for high-current reversed field pinch plasmas. These states feature the presence of transport barriers in the core plasma. Here we present a method for computing the equilibrium magnetic surfaces for these states in the force-free approximation, which has been implemented in the SHEq code. The method is based on the superposition of a zeroth-order axisymmetric equilibrium and of a first-order helical perturbation computed according to Newcomb's equation supplemented with edge magnetic field measurements. The mapping of the measured electron temperature profiles, soft x-ray emission and interferometric density measurements on the computed magnetic surfaces demonstrates the quality of the equilibrium reconstruction. The procedure for computing flux surface averages is illustrated, and applied to the evaluation of the thermal conductivity profile. The consistency of the evaluated equilibria with Ohm's law is also discussed.

  8. Image assessment with multislice CT coronary angiography; Valutazione delle immagini in coronarografia TC

    Energy Technology Data Exchange (ETDEWEB)

    Cademartiri, Filippo [Erasmus Medical Center, Rotterdam (Netherlands). Dipartimento di Radiologia; Marano, Riccardo [G. D' Annunzio Univ., Chieti (Italy). Dipartimento di Radiologia; Luccichenti, Giacomo [Fondazione Biomedica Europea ONLUS, Roma (Italy)] [and others

    2005-03-01

    Aim: To investigate the diagnostic accuracy of two different protocols for image evaluation used in multislice computed tomography coronary angiography (MSCT-CA). Materials and methods: Sixty patients with suspected coronary artery disease undergoing conventional coronary angiography (CA) were enrolled for MSCT-CA. All patients underwent 16-row MSCT (Sensation 16, Siemens, Germany) with the following parameters: detector rows 16, collimation 0.75 mm, gantry rotation time 375 ms. Two independent observers assessed the images for significant stenosis using a protocol with standard projections and a three-dimensional protocol. The diagnostic accuracy for both methods was calculated using quantitative CA as a reference standard. Results: The sensitivity, specificity, negative predictive value and positive predictive value obtained with the conventional projection protocol and with three-dimensional protocol were: 54% and 93%, 97% and 97%, 76% and 86%, 92% and 99%, respectively. Conclusions: Conventional projection in the assessment of MSCT-CA provide insufficient diagnostic accuracy compared with three-dimensional processing. [Italian] Scopo: Valutare l'accuratezza diagnostica di due diversi protocolli di visualizzazione delle immagini utilizzati in angiografia con tomografia computerizzata multistrato (AC-TCMS) nella valutazione delle arterie coronarie. Materiale e metodi: Sessanta pazienti con sospetta malattia coronarica, sottoposti a coronarografia convenzionale, sono stati esaminati con AC-TCMS. Tutti i pazienti sono stati valutati con un'apparecchiatura TC a 16 strati (Sensation 16, Siemens, Germania). I parametri di scansione sono stati i seguenti: detettori 16, collimazione 0,75 mm, tempo di rotazione del tubo radiogeno 375 ms. Due osservatori in cieco hanno valutato le stenosi coronariche significative con due protocolli di valutazione: proiezione standard e protocollo tri-dimensionale. L'accuratezza diagnostica di ciascun protocollo e

  9. Generalized helicity and Beltrami fields

    Energy Technology Data Exchange (ETDEWEB)

    Buniy, Roman V., E-mail: roman.buniy@gmail.com [Schmid College of Science, Chapman University, Orange, CA 92866 (United States); Isaac Newton Institute, University of Cambridge, Cambridge, CB3 0EH (United Kingdom); Kephart, Thomas W., E-mail: tom.kephart@gmail.com [Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37235 (United States); Isaac Newton Institute, University of Cambridge, Cambridge, CB3 0EH (United Kingdom)

    2014-05-15

    We propose covariant and non-abelian generalizations of the magnetic helicity and Beltrami equation. The gauge invariance, variational principle, conserved current, energy–momentum tensor and choice of boundary conditions elucidate the subject. In particular, we prove that any extremal of the Yang–Mills action functional 1/4 ∫{sub Ω}trF{sub μν}F{sup μν}d{sup 4}x subject to the local constraint ε{sup μναβ}trF{sub μν}F{sub αβ}=0 satisfies the covariant non-abelian Beltrami equation. -- Highlights: •We introduce the covariant non-abelian helicity and Beltrami equation. •The Yang–Mills action and instanton term constraint lead to the Beltrami equation. •Solutions of the Beltrami equation conserve helicity.

  10. Tunneling into and between helical edge states: Fermionic approach

    Science.gov (United States)

    Aristov, D. N.; Niyazov, R. A.

    2016-07-01

    We study the four-terminal junction of spinless Luttinger liquid wires, which describes either a corner junction of two helical edge states of topological insulators or the tunneling from the spinful wire into the helical edge state. We use the fermionic representation and the scattering state formalism, in order to compute the renormalization group (RG) equations for the linear response conductances. We establish our approach by considering a junction between two possibly nonequivalent helical edge states and find an agreement with the earlier analysis of this situation. Tunneling from the tip of the spinful wire to the edge state is further analyzed which requires some modification of our formalism. In the latter case we demonstrate (i) the existence of both fixed lines and conventional fixed points of RG equations, and (ii) certain proportionality relations holding for conductances during renormalization. The scaling exponents and phase portraits are obtained in all cases.

  11. Diagnosis of temporal bone diseases using three-dimensional images with multislice CT

    Energy Technology Data Exchange (ETDEWEB)

    Toyama, Yoshihiro; Togami, Taro; Murota, Makiko; Fukunaga, Kotaro; Hino, Ichiro; Sato, Katashi; Ohkawa, Motoomi [Kagawa Medical Univ., Miki (Japan)

    2001-08-01

    We evaluated the usefulness of three-dimensional images with multislice CT in the temporal bone diseases. Fifty-nine cases (26 with medial otitis, 8 choresteatoma, 10 congenital malformation, 3 high jugular bulb, 2 otosclerosis, and 10 others) were included in this study. In the ossicular and inner ear lesions, oblique multiplanar images of the long axis of each ossicle was useful the detection of abnormality. Structural deformity of ossicles and bony labyrinth were clearly delineated by surface rendering images. (author)

  12. On-site Rapid Diagnosis of Intracranial Hematoma using Portable Multi-slice Microwave Imaging System

    Science.gov (United States)

    Mobashsher, Ahmed Toaha; Abbosh, A. M.

    2016-11-01

    Rapid, on-the-spot diagnostic and monitoring systems are vital for the survival of patients with intracranial hematoma, as their conditions drastically deteriorate with time. To address the limited accessibility, high costs and static structure of currently used MRI and CT scanners, a portable non-invasive multi-slice microwave imaging system is presented for accurate 3D localization of hematoma inside human head. This diagnostic system provides fast data acquisition and imaging compared to the existing systems by means of a compact array of low-profile, unidirectional antennas with wideband operation. The 3D printed low-cost and portable system can be installed in an ambulance for rapid on-site diagnosis by paramedics. In this paper, the multi-slice head imaging system’s operating principle is numerically analysed and experimentally validated on realistic head phantoms. Quantitative analyses demonstrate that the multi-slice head imaging system is able to generate better quality reconstructed images providing 70% higher average signal to clutter ratio, 25% enhanced maximum signal to clutter ratio and with around 60% hematoma target localization compared to the previous head imaging systems. Nevertheless, numerical and experimental results demonstrate that previous reported 2D imaging systems are vulnerable to localization error, which is overcome in the presented multi-slice 3D imaging system. The non-ionizing system, which uses safe levels of very low microwave power, is also tested on human subjects. Results of realistic phantom and subjects demonstrate the feasibility of the system in future preclinical trials.

  13. Brownian motion of helical flagella.

    Science.gov (United States)

    Hoshikawa, H; Saito, N

    1979-07-01

    We develops a theory of the Brownian motion of a rigid helical object such as bacterial flagella. The statistical properties of the random forces acting on the helical object are discussed and the coefficients of the correlations of the random forces are determined. The averages , and are also calculated where z and theta are the position along and angle around the helix axis respectively. Although the theory is limited to short time interval, direct comparison with experiment is possible by using the recently developed cinematography technique.

  14. Optical and Infrared Helical Metamaterials

    Directory of Open Access Journals (Sweden)

    Kaschke Johannes

    2016-09-01

    Full Text Available By tailoring metamaterials with chiral unit cells, giant optical activity and strong circular dichroism have been achieved successfully over the past decade. Metamaterials based on arrays of metal helices have revolutionized the field of chiral metamaterials, because of their capability of exhibiting these pronounced chiro-optical effects over previously unmatched bandwidths. More recently, a large number of new metamaterial designs based on metal helices have been introduced with either optimized optical performance or other chiro-optical properties for novel applications.

  15. A hypothesis on neutrino helicity

    CERN Document Server

    Sahin, I

    2016-01-01

    It is firmly established by experimental results that neutrinos are almost 100\\% longitudinally polarized and left-handed. It is also confirmed by neutrino oscillation experiments that neutrinos have tiny but non-zero masses. Since the helicity is not a Lorentz invariant quantity for massive particles, neutrinos can not be strictly left-handed. On the other hand, it is generally assumed that ultrarelativistic massive fermions can be described well enough by the Weyl equations. We discuss the validity of this assumption and propose a new hypothesis according to which neutrinos can be described by pure helicity states although they are not massless.

  16. Visualisation of intracerebral haemorrhage with flat-detector CT compared to multislice CT: results in 44 cases.

    Science.gov (United States)

    Struffert, Tobias; Richter, Gregor; Engelhorn, Tobias; Doelken, Marc; Goelitz, Philipp; Kalender, Willi A; Ganslandt, Oliver; Doerfler, Arnd

    2009-03-01

    The aim of the study was to test the reliability of intracerebral haemorrhage (ICH) detection with C-arm-mounted flat-detector computed tomography (FD-CT) in the angio suite as compared to multislice CT (MSCT). In this study 44 patients with 45 ICH were included. All patients were investigated with MSCT and FD-CT during angiographic evaluation. As a control group we included 16 patients without ICH. In each haematoma we assessed volumetric data of the ICH and counted the numbers of ICH-positive slices. Using interobserver ratings, we additionally investigated the potential of FD-CT to serve as a diagnostic tool to detect ICH. In FD-CT three haematomas were not detected because of motion and beam-hardening artefacts in the region close to the skull base. The r value for the degree of interobserver agreement for the number of slices was 0.95 for MSCT and 0.94 for FD-CT. Measurements of the area and the calculated volume of the ICH showed high inter- and intraobserver agreement. Our results indicate that FD-CT is a helpful tool in the daily emergency management of ICH patients as detection of ICH was found to be nearly as reliable as in MSCT. Limitations of this technology are motion and beam-hardening artefacts that may mask small haematomas located in the posterior fossa or the skull base.

  17. Peripheral pulmonary arteries: identification at multi-slice spiral CT with 3D reconstruction

    Energy Technology Data Exchange (ETDEWEB)

    Coche, Emmanuel; Pawlak, Sebastien; Dechambre, Stephane; Maldague, Baudouin [Department of Radiology, St. Luc Hospital, UCL, Avenue Hippocrate, 10, 1200 Brussels (Belgium)

    2003-04-01

    Our objective was to analyze the peripheral pulmonary arteries using thin-collimation multi-slice spiral CT. Twenty consecutive patients underwent enhanced-spiral multi-slice CT using 1-mm collimation. Two observers analyzed the pulmonary arteries by consensus on a workstation. Each artery was identified on axial and 3D shaded-surface display reconstruction images. Each subsegmental artery was measured at a mediastinal window setting and compared with anatomical classifications. The location and branching of every subsegmental artery was recorded. The number of well-visualized sub-subsegmental arteries at a mediastinal window setting was compared with those visualized at a lung window setting. Of 800 subsegmental arteries, 769 (96%) were correctly visualized and 123 accessory subsegmental arteries were identified using the mediastinal window setting. One thousand ninety-two of 2019 sub-subsegmental arteries (54%) identified using the lung window setting were correctly visualized using the mediastinal window setting. Enhanced multi-slice spiral CT with thin collimation can be used to analyze precisely the subsegmental pulmonary arteries and may identify even more distal pulmonary arteries. (orig.)

  18. Peripheral pulmonary arteries: identification at multi-slice spiral CT with 3D reconstruction.

    Science.gov (United States)

    Coche, Emmanuel; Pawlak, Sebastien; Dechambre, Stéphane; Maldague, Baudouin

    2003-04-01

    Our objective was to analyze the peripheral pulmonary arteries using thin-collimation multi-slice spiral CT. Twenty consecutive patients underwent enhanced-spiral multi-slice CT using 1-mm collimation. Two observers analyzed the pulmonary arteries by consensus on a workstation. Each artery was identified on axial and 3D shaded-surface display reconstruction images. Each subsegmental artery was measured at a mediastinal window setting and compared with anatomical classifications. The location and branching of every subsegmental artery was recorded. The number of well-visualized sub-subsegmental arteries at a mediastinal window setting was compared with those visualized at a lung window setting. Of 800 subsegmental arteries, 769 (96%) were correctly visualized and 123 accessory subsegmental arteries were identified using the mediastinal window setting. One thousand ninety-two of 2019 sub-subsegmental arteries (54%) identified using the lung window setting were correctly visualized using the mediastinal window setting. Enhanced multi-slice spiral CT with thin collimation can be used to analyze precisely the subsegmental pulmonary arteries and may identify even more distal pulmonary arteries.

  19. Comparison between multislice and cone-beam computerized tomography in the volumetric assessment of cleft palate.

    Science.gov (United States)

    Albuquerque, Marco Antonio; Gaia, Bruno Felipe; Cavalcanti, Marcelo Gusmão Paraíso

    2011-08-01

    The aim of this study was to determine the applicability of multislice and cone-beam computerized tomography (CT) in the assessment of bone defects in patients with oral clefts. Bone defects were produced in 9 dry skulls to mimic oral clefts. All defects were modeled with wax. The skulls were submitted to multislice and cone-beam CT. Subsequently, physical measurements were obtained by the Archimedes principle of water displacement of wax models. The results demonstrated that multislice and cone-beam CT showed a high efficiency rate and were considered to be effective for volumetric assessment of bone defects. It was also observed that both CT modalities showed excellent results with high reliability in the study of the volume of bone defects, with no difference in performance between them. The clinical applicability of our research has shown these CT modalities to be immediate and direct, and they is important for the diagnosis and therapeutic process of patients with oral cleft. Copyright © 2011 Mosby, Inc. All rights reserved.

  20. Magnetic Helicity Injection in Solar Active Regions

    Institute of Scientific and Technical Information of China (English)

    Hong-Qi Zhang

    2006-01-01

    We present the evolution of magnetic field and its relationship with magnetic (current) helicity in solar active regions from a series of photospheric vector magnetograms obtained by Huairou Solar Observing Station, longitudinal magnetograms by MDI of SOHO and white light images of TRACE. The photospheric current helicity density is a quantity reflecting the local twisted magnetic field and is related to the remaining magnetic helicity in the photosphere, even if the mean current helicity density brings the general chiral property in a layer of solar active regions. As new magnetic flux emerges in active regions, changes of photospheric current helicity density with the injection of magnetic helicity into the corona from the subatmosphere can be detected, including changes in sign caused by the injection of magnetic helicity of opposite sign. Because the injection rate of magnetic helicity and photospheric current helicity density have different means in the solar atmosphere,the injected magnetic helicity is probably not proportional to the current helicity density remaining in the photosphere. The evidence is that rotation of sunspots does not synchronize exactly with the twist of photospheric transverse magnetic field in some active regions (such as, delta active regions). They represent different aspects of magnetic chirality. A combined analysis of the observational magnetic helicity parameters actually provides a relative complete picture of magnetic helicity and its transfer in the solar atmosphere.

  1. The Transport of Relative Canonical Helicity

    CERN Document Server

    You, Setthivoine

    2012-01-01

    The evolution of relative canonical helicity is examined in the two-fluid magnetohydrodynamic formalism. Canonical helicity is defined here as the helicity of the plasma species' canonical momentum. The species' canonical helicity are coupled together and can be converted from one into the other while the total gauge-invariant relative canonical helicity remains globally invariant. The conversion is driven by enthalpy differences at a surface common to ion and electron canonical flux tubes. The model provides an explanation for why the threshold for bifurcation in counter-helicity merging depends on the size parameter. The size parameter determines whether magnetic helicity annihilation channels enthalpy into the magnetic flux tube or into the vorticity flow tube components of the canonical flux tube. The transport of relative canonical helicity constrains the interaction between plasma flows and magnetic fields, and provides a more general framework for driving flows and currents from enthalpy or inductive b...

  2. Applications of 2D helical vortex dynamics

    DEFF Research Database (Denmark)

    Okulov, Valery; Sørensen, Jens Nørkær

    2010-01-01

    In the paper, we show how the assumption of helical symmetry in the context of 2D helical vortices can be exploited to analyse and to model various cases of rotating flows. From theory, examples of three basic applications of 2D dynamics of helical vortices embedded in flows with helical symmetry...... of the vorticity field are addressed. These included some of the problems related to vortex breakdown, instability of far wakes behind rotors and vortex theory of ideal rotors....

  3. Influence of Magnetic Helicity in MHD

    CERN Document Server

    Candelaresi, Simon; Brandenburg, Axel

    2010-01-01

    Observations have shown that the Sun's magnetic field has helical structures. The helicity content in magnetic field configurations is a crucial constraint on the dynamical evolution of the system. Since helicity is connected with the number of links we investigate configurations with interlocked magnetic flux rings and one with unlinked rings. It turns out that it is not the linking of the tubes which affects the magnetic field decay, but the content of magnetic helicity.

  4. On the triple correlations in helical turbulence

    CERN Document Server

    Chkhetiani, O

    1997-01-01

    The evolution of correlation characteristics in homogeneous helical turbulence is considered. Additional K'arm'an-Howarth type equations, describing the evolution of the mixed correlation tensor of the velocity and vorticity are obtained. In the helical scaling region, the solution of obtained equation gives the exact relation between antisymmetric component of a rank-three tensor and the average dissipation of helicity. This relation is a helical analogue of Kolmogorov's known 4/5 law.

  5. spinney: A Form library for helicity spinors

    Science.gov (United States)

    Cullen, G.; Koch-Janusz, M.; Reiter, T.

    2011-11-01

    In this work, the library spinney is presented, which provides an implementation of helicity spinors and related algorithms for the symbolical manipulation program Form. The package is well suited for symbolic amplitude calculations both in traditional, Feynman diagram based approaches and unitarity-based techniques. Program summaryProgram title: spinney Catalogue identifier: AEJQ_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEJQ_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 21 128 No. of bytes in distributed program, including test data, etc.: 377 589 Distribution format: tar.gz Programming language: Form Computer: Any supporting the Form language Operating system: Any supporting the Form language Classification: 4.4, 5, 11.1 Nature of problem: Implementation of the spinor-helicity formalism Solution method: Form implementation Running time: From actual calculations of all six-point one-loop diagrams of the process gg→qq¯qq bounds of 50 ms

  6. Right- and Left-Handed Helices, What is in between? Interconversion of Helical Structures of Alternating Pyridinedicarboxamide/m-(phenylazo)azobenzene Oligomers.

    Science.gov (United States)

    Tao, Peng; Parquette, Jon R; Hadad, Christopher M

    2012-12-11

    Some unnatural polymers/oligomers have been designed to adopt a well-defined, compact, three-dimensional folding capability. Azobenzene units are common linkages in these oligomer designs. Two alternating pyridinedicarboxamide/m-(phenylazo)azobenzene oligomers that can fold into both right- and left-handed helices were studied computationally in order to understand their dynamical properties. Helical structures were shown to be the global minima among the many different conformations generated from the Monte Carlo simulations, and extended conformations have higher potential energies than compact ones. To understand the interconversion process between right- and left-handed helices, replica-exchange molecular dynamic (REMD) simulations were performed on both oligomers, and with this method, both right- and left-handed helices were successfully sampled during the simulations. REMD trajectories revealed twisted conformations as intermediate structures in the interconversion pathway between the two helical forms of these azobenzene oligomers. This mechanism was observed in both oligomers in current study and occurred locally in the larger oligomer. This discovery indicates that the interconversion between helical structures with different handedness goes through a compact and partially folded structure instead of globally unfold and extended structure. This is also verified by the nudged elastic band (NEB) calculations. The temperature weighted histogram analysis method (T-WHAM) was applied on the REMD results to generate contour maps of the potential of mean force (PMF). Analysis showed that right- and left-handed helices are equally sampled in these REMD simulations. In large oligomers, both right- and left-handed helices can be adopted by different parts of the molecule simultaneously. The interconversion between two helical forms can occur in the middle of the helical structure and not necessarily at the termini of the oligomer.

  7. Study of CdTe:Cl and CdZnTe detectors for medical multi-slices X-ray Computed Tomography; Etude de detecteurs en CdTe:Cl et CdZnTe pour la tomographie X medicale multicoupes

    Energy Technology Data Exchange (ETDEWEB)

    Ricq, St

    1999-09-28

    The application of CdTe and CdZnTe detectors to medical X-ray Computed Tomography have been investigated. Different electrodes (Au, Pt, In) have been deposited on CdZnTe HPBM and on CdTe:ClTHM. Their injection properties have been determined with Current-Voltage characteristics. Under X-ray in CT conditions, injection currents measurements reveal trapped carriers space-charges formation. The same way, the comparisons of the responses to X-beam cut-off with various injection possibilities enable to follow the space-charges evolutions and then to determine the predominant traps types. Nevertheless, both hole and electron traps are responsible for the memory effect e.g. the currents levels dependence with irradiation history. This effect is noticed in particular on responses to fast flux variations that simulate scanner's conditions. Trap levels probably corresponding to native defects are responsible for these limitations. In order to make such detectors suitable for X-ray Computed Tomography, significant progresses in CdTe for CdZnTe crystal growth with an important defects densities reduction (factor 10), or possibly counting mode operation, seem necessary. (author)

  8. Hybrid helical snakes and rotators for RHIC

    Energy Technology Data Exchange (ETDEWEB)

    Courant, E.D.

    1995-06-13

    The spin rotators and Siberian snakes presently envisaged for RHIC utilize helical dipole magnets. The snakes and the rotators each consist of four helices, each with a full twist (360{degrees}) of the field. Here we investigate an alternate layout, namely combinations of helical and pure bending magnet, and show that this may have advantages.

  9. Enantiomeric differentiation by synthetic helical polymers.

    Science.gov (United States)

    Yashima, Eiji; Iida, Hiroki; Okamoto, Yoshio

    2013-01-01

    Recent advances in the synthesis of helical polymers and their applications as chiral materials, in particular chiral stationary phases (CSPs), for high-performance liquid chromatography (HPLC) are reviewed with an emphasis on the key role of the helical conformations with one-handedness for the prominent chiral recognition of enantiomers. The historical background of artificial optically active helical polymers is also briefly described.

  10. Conductance through a helical state in an Indium antimonide nanowire.

    Science.gov (United States)

    Kammhuber, J; Cassidy, M C; Pei, F; Nowak, M P; Vuik, A; Gül, Ö; Car, D; Plissard, S R; Bakkers, E P A M; Wimmer, M; Kouwenhoven, L P

    2017-09-07

    The motion of an electron and its spin are generally not coupled. However in a one-dimensional material with strong spin-orbit interaction (SOI) a helical state may emerge at finite magnetic fields, where electrons of opposite spin will have opposite momentum. The existence of this helical state has applications for spin filtering and cooper pair splitter devices and is an essential ingredient for realizing topologically protected quantum computing using Majorana zero modes. Here, we report measurements of a quantum point contact in an indium antimonide nanowire. At magnetic fields exceeding 3 T, the 2 e (2)/h conductance plateau shows a re-entrant feature toward 1 e (2)/h which increases linearly in width with magnetic field. Rotating the magnetic field clearly attributes this experimental signature to SOI and by comparing our observations with a numerical model we extract a spin-orbit energy of approximately 6.5 meV, which is stronger than the spin-orbit energy obtained by other methods.Indium antimonide nanowires have large spin-orbit coupling, which can give rise to helical states that are an important part of proposals for topological quantum computing. Here the authors measure conductance through the helical states and extract a larger spin-orbit energy than obtained before.

  11. Multislice CT as a Primary Screening Tool for the Prediction of an Involved Mesorectal Fascia and Distant Metastases in Primary Rectal Cancer : A Multicenter Study

    NARCIS (Netherlands)

    Wolberink, Steven V. R. C.; Beets-Tan, Regina G. H.; de Haas-Kock, Danielle F. M.; van de Jagt, Eric J.; Span, Mark M.; Wiggers, Theo

    2009-01-01

    PURPOSE: The purposes of this study were to assess whether multislice CT can identify tumors having a free or involved circumferential margin, to investigate the additional role of multislice CT as a "one-stop shopping'' staging tool for staging nodal and distant metastases. METHODS: A total of 250

  12. Multislice CT as a Primary Screening Tool for the Prediction of an Involved Mesorectal Fascia and Distant Metastases in Primary Rectal Cancer : A Multicenter Study

    NARCIS (Netherlands)

    Wolberink, Steven V. R. C.; Beets-Tan, Regina G. H.; de Haas-Kock, Danielle F. M.; van de Jagt, Eric J.; Span, Mark M.; Wiggers, Theo

    PURPOSE: The purposes of this study were to assess whether multislice CT can identify tumors having a free or involved circumferential margin, to investigate the additional role of multislice CT as a "one-stop shopping'' staging tool for staging nodal and distant metastases. METHODS: A total of 250

  13. Performance tests on helical Savonius rotors

    Energy Technology Data Exchange (ETDEWEB)

    Kamoji, M.A.; Kedare, S.B. [Department of Energy Science and Engineering, Indian Institute of Technology, Bombay (India); Prabhu, S.V. [Department of Mechanical Engineering, Indian Institute of Technology, Bombay (India)

    2009-03-15

    Conventional Savonius rotors have high coefficient of static torque at certain rotor angles and a negative coefficient of static torque from 135 to 165 and from 315 to 345 in one cycle of 360 . In order to decrease this variation in static torque from 0 to 360 , a helical Savonius rotor with a twist of 90 is proposed. In this study, tests on helical Savonius rotors are conducted in an open jet wind tunnel. Coefficient of static torque, coefficient of torque and coefficient of power for each helical Savonius rotor are measured. The performance of helical rotor with shaft between the end plates and helical rotor without shaft between the end plates at different overlap ratios namely 0.0, 0.1 and 0.16 is compared. Helical Savonius rotor without shaft is also compared with the performance of the conventional Savonius rotor. The results indicate that all the helical Savonius rotors have positive coefficient of static torque at all the rotor angles. The helical rotors with shaft have lower coefficient of power than the helical rotors without shaft. Helical rotor without shaft at an overlap ratio of 0.0 and an aspect ratio of 0.88 is found to have almost the same coefficient of power when compared with the conventional Savonius rotor. Correlation for coefficient of torque and power is developed for helical Savonius rotor for a range of Reynolds numbers studied. (author)

  14. Predictive supracolloidal helices from patchy particles

    Science.gov (United States)

    Guo, Ruohai; Mao, Jian; Xie, Xu-Ming; Yan, Li-Tang

    2014-11-01

    A priori prediction of supracolloidal architectures from nanoparticle and colloidal assembly is a challenging goal in materials chemistry and physics. Despite intense research in this area, much less has been known about the predictive science of supracolloidal helices from designed building blocks. Therefore, developing conceptually new rules to construct supracolloidal architectures with predictive helicity is becoming an important and urgent task of great scientific interest. Here, inspired by biological helices, we show that the rational design of patchy arrangement and interaction can drive patchy particles to self-assemble into biomolecular mimetic supracolloidal helices. We further derive a facile design rule for encoding the target supracolloidal helices, thus opening the doors to the predictive science of these supracolloidal architectures. It is also found that kinetics and reaction pathway during the formation of supracolloidal helices offer a unique way to study supramolecular polymerization, and that well-controlled supracolloidal helices can exhibit tailorable circular dichroism effects at visible wavelengths.

  15. A helical scintillating fiber hodoscope

    CERN Document Server

    Altmeier, M; Bisplinghoff, J; Bissel, T; Bollmann, R; Busch, M; Büsser, K; Colberg, T; Demiroers, L; Diehl, O; Dohrmann, F; Engelhardt, H P; Eversheim, P D; Felden, O; Gebel, R; Glende, M; Greiff, J; Gross, A; Gross-Hardt, R; Hinterberger, F; Jahn, R; Jeske, M; Jonas, E; Krause, H; Lahr, U; Langkau, R; Lindemann, T; Lindlein, J; Maier, R; Maschuw, R; Mayer-Kuckuck, T; Meinerzhagen, A; Naehle, O; Pfuff, M; Prasuhn, D; Rohdjess, H; Rosendaal, D; Von Rossen, P; Sanz, B; Schirm, N; Schulz-Rojahn, M; Schwarz, V; Scobel, W; Thomas, S; Trelle, H J; Weise, E; Wellinghausen, A; Wiedmann, W; Woller, K; Ziegler, R

    1999-01-01

    A novel scintillating fiber hodoscope in helically cylindric geometry has been developed for detection of low multiplicity events of fast protons and other light charged particles in the internal target experiment EDDA at the Cooler Synchrotron COSY. The hodoscope consists of 640 scintillating fibers (2.5 mm diameter), arranged in four layers surrounding the COSY beam pipe. The fibers are helically wound in opposing directions and read out individually using 16-channel photomultipliers connected to a modified commercial encoding system. The detector covers an angular range of 9 deg. <= THETA<=72 deg. and 0 deg. <=phi (cursive,open) Greek<=360 deg. in the lab frame. The detector length is 590 mm, the inner diameter 161 mm. Geometry and granularity of the hodoscope afford a position resolution of about 1.3 mm. The detector design took into consideration a maximum of reliability and a minimum of maintenance. An LED array may be used for monitoring purposes. (author)

  16. A helical scintillating fiber hodoscope

    Energy Technology Data Exchange (ETDEWEB)

    Altmeier, M.; Bauer, F.; Bisplinghoff, J.; Bissel, T.; Bollmann, R.; Busch, M.; Buesser, K.; Colberg, T.; Demiroers, L.; Diehl, O.; Dohrmann, F.; Engelhardt, H.P.; Eversheim, P.D.; Felden, O.; Gebel, R.; Glende, M.; Greiff, J.; Gross, A.; Gross-Hardt, R.; Hinterberger, F.; Jahn, R.; Jeske, M.; Jonas, E.; Krause, H.; Lahr, U.; Langkau, R.; Lindemann, T.; Lindlein, J.; Maier, R.; Maschuw, R.; Mayer-Kuckuck, T.; Meinerzhagen, A.; Naehle, O.; Pfuff, M.; Prasuhn, D.; Rohdjess, H.; Rosendaal, D.; Rossen, P. von; Sanz, B.; Schirm, N.; Schulz-Rojahn, M.; Schwarz, V.; Scobel, W.; Thomas, S.; Trelle, H.J.; Weise, E.; Wellinghausen, A.; Wiedmann, W.; Woller, K.; Ziegler, R

    1999-07-21

    A novel scintillating fiber hodoscope in helically cylindric geometry has been developed for detection of low multiplicity events of fast protons and other light charged particles in the internal target experiment EDDA at the Cooler Synchrotron COSY. The hodoscope consists of 640 scintillating fibers (2.5 mm diameter), arranged in four layers surrounding the COSY beam pipe. The fibers are helically wound in opposing directions and read out individually using 16-channel photomultipliers connected to a modified commercial encoding system. The detector covers an angular range of 9 deg. {<=}{theta}{<=}72 deg. and 0 deg. {<=}phi (cursive,open) Greek{<=}360 deg. in the lab frame. The detector length is 590 mm, the inner diameter 161 mm. Geometry and granularity of the hodoscope afford a position resolution of about 1.3 mm. The detector design took into consideration a maximum of reliability and a minimum of maintenance. An LED array may be used for monitoring purposes. (author)

  17. Adjustable phase planar helical undulator

    Science.gov (United States)

    Carr, Roger G.; Lidia, Steve

    1993-11-01

    We present here the design description of a new type of planar helical undulator, which we are constructing for the SPEAR storage ring at the Stanford Synchrotron Radiation Laboratory. It comprises four rows of pure permanent magnet blocks, one row in each quadrant about the axis defined by the electron beam. Rows may be translated longitudinally with respect to each other to change the helicity of the magnetic field they create at the position of the beam. They may also be translated longitudinally to vary the energy of the x-rays emitted, unlike designs where this function is performed by varying the gap between the rows. This work includes numerical calculations of the fields, electron trajectories, and x-ray spectra, including off-axis effects.

  18. An experimental superconducting helical undulator

    Energy Technology Data Exchange (ETDEWEB)

    Caspi, S.; Taylor, C. [Lawrence Berkeley Lab., CA (United States)

    1995-12-31

    Improvements in the technology of superconducting magnets for high energy physics and recent advancements in SC materials with the artificial pinning centers (APC){sup 2}, have made a bifilar helical SC device an attractive candidate for a single-pass free electron laser (FEL){sup 3}. Initial studies have suggested that a 6.5 mm inner diameter helical device, with a 27 mm period, can generate a central field of 2-2.5 Tesla. Additional studies have also suggested that with a stored energy of 300 J/m, such a device can be made self-protecting in the event of a quench. However, since the most critical area associated with high current density SC magnets is connected with quenching and training, a short experimental device will have to be built and tested. In this paper we discuss technical issues relevant to the construction of such a device, including a conceptual design, fields, and forces.

  19. Emulsification-Induced Homohelicity in Racemic Helical Polymer for Preparing Optically Active Helical Polymer Nanoparticles.

    Science.gov (United States)

    Zhao, Biao; Deng, Jinrui; Deng, Jianping

    2016-04-01

    Optically active nano- and microparticles have constituted a significant category of advanced functional materials. However, constructing optically active particles derived from synthetic helical polymers still remains as a big challenge. In the present study, it is attempted to induce a racemic helical polymer (containing right- and left-handed helices in equal amount) to prefer one predominant helicity in aqueous media by using emulsifier in the presence of chiral additive (emulsification process). Excitingly, the emulsification process promotes the racemic helical polymer to unify the helicity and directly provides optically active nanoparticles constructed by chirally helical polymer. A possible mechanism is proposed to explain the emulsification-induced homohelicity effect. The present study establishes a novel strategy for preparing chirally helical polymer-derived optically active nanoparticles based on racemic helical polymers.

  20. All Next-to-Maximally-Helicity-Violating One-Loop Gluon Amplitudes in N=4 Super-Yang-Mills Theory

    CERN Document Server

    Bern, Z; Kosower, D A; Bern, Zvi; Dixon, Lance J.; Kosower, David A.

    2004-01-01

    We compute the next-to-MHV one-loop n-gluon amplitudes in N=4 super-Yang-Mills theory. These amplitudes contain three negative-helicity gluons and an arbitrary number of positive-helicity gluons, and are the first infinite series of amplitudes beyond the simplest, MHV, amplitudes. We also discuss some aspects of their twistor-space structure.

  1. Helical Antimicrobial Sulfono- {gamma} -AApeptides

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yaqiong; Wu, Haifan; Teng, Peng; Bai, Ge; Lin, Xiaoyang; Zuo, Xiaobing; Cao, Chuanhai; Cai, Jianfeng

    2015-06-11

    Host-defense peptides (HDPs) such as magainin 2 have emerged as potential therapeutic agents combating antibiotic resistance. Inspired by their structures and mechanism of action, herein we report the fi rst example of antimicrobial helical sulfono- γ - AApeptide foldamers. The lead molecule displays broad-spectrum and potent antimicrobial activity against multi-drug-resistant Gram- positive and Gram-negative bacterial pathogens. Time-kill studies and fl uorescence microscopy suggest that sulfono- γ -AApeptides eradicate bacteria by taking a mode of action analogous to that of HDPs. Clear structure - function relationships exist in the studied sequences. Longer sequences, presumably adopting more-de fi ned helical structures, are more potent than shorter ones. Interestingly, the sequence with less helical propensity in solution could be more selective than the stronger helix-forming sequences. Moreover, this class of antimicrobial agents are resistant to proteolytic degradation. These results may lead to the development of a new class of antimicrobial foldamers combating emerging antibiotic-resistant pathogens.

  2. Helically twisted photonic crystal fibres.

    Science.gov (United States)

    Russell, P St J; Beravat, R; Wong, G K L

    2017-02-28

    Recent theoretical and experimental work on helically twisted photonic crystal fibres (PCFs) is reviewed. Helical Bloch theory is introduced, including a new formalism based on the tight-binding approximation. It is used to explore and explain a variety of unusual effects that appear in a range of different twisted PCFs, including fibres with a single core and fibres with N cores arranged in a ring around the fibre axis. We discuss a new kind of birefringence that causes the propagation constants of left- and right-spinning optical vortices to be non-degenerate for the same order of orbital angular momentum (OAM). Topological effects, arising from the twisted periodic 'space', cause light to spiral around the fibre axis, with fascinating consequences, including the appearance of dips in the transmission spectrum and low loss guidance in coreless PCF. Discussing twisted fibres with a single off-axis core, we report that optical activity in a PCF is opposite in sign to that seen in a step-index fibre. Fabrication techniques are briefly described and emerging applications reviewed. The analytical results of helical Bloch theory are verified by an extensive series of 'numerical experiments' based on finite-element solutions of Maxwell's equations in a helicoidal frame.This article is part of the themed issue 'Optical orbital angular momentum'. © 2017 The Authors.

  3. Helically twisted photonic crystal fibres

    Science.gov (United States)

    Russell, P. St. J.; Beravat, R.; Wong, G. K. L.

    2017-02-01

    Recent theoretical and experimental work on helically twisted photonic crystal fibres (PCFs) is reviewed. Helical Bloch theory is introduced, including a new formalism based on the tight-binding approximation. It is used to explore and explain a variety of unusual effects that appear in a range of different twisted PCFs, including fibres with a single core and fibres with N cores arranged in a ring around the fibre axis. We discuss a new kind of birefringence that causes the propagation constants of left- and right-spinning optical vortices to be non-degenerate for the same order of orbital angular momentum (OAM). Topological effects, arising from the twisted periodic `space', cause light to spiral around the fibre axis, with fascinating consequences, including the appearance of dips in the transmission spectrum and low loss guidance in coreless PCF. Discussing twisted fibres with a single off-axis core, we report that optical activity in a PCF is opposite in sign to that seen in a step-index fibre. Fabrication techniques are briefly described and emerging applications reviewed. The analytical results of helical Bloch theory are verified by an extensive series of `numerical experiments' based on finite-element solutions of Maxwell's equations in a helicoidal frame. This article is part of the themed issue 'Optical orbital angular momentum'.

  4. Helically twisted photonic crystal fibres

    Science.gov (United States)

    Beravat, R.; Wong, G. K. L.

    2017-01-01

    Recent theoretical and experimental work on helically twisted photonic crystal fibres (PCFs) is reviewed. Helical Bloch theory is introduced, including a new formalism based on the tight-binding approximation. It is used to explore and explain a variety of unusual effects that appear in a range of different twisted PCFs, including fibres with a single core and fibres with N cores arranged in a ring around the fibre axis. We discuss a new kind of birefringence that causes the propagation constants of left- and right-spinning optical vortices to be non-degenerate for the same order of orbital angular momentum (OAM). Topological effects, arising from the twisted periodic ‘space’, cause light to spiral around the fibre axis, with fascinating consequences, including the appearance of dips in the transmission spectrum and low loss guidance in coreless PCF. Discussing twisted fibres with a single off-axis core, we report that optical activity in a PCF is opposite in sign to that seen in a step-index fibre. Fabrication techniques are briefly described and emerging applications reviewed. The analytical results of helical Bloch theory are verified by an extensive series of ‘numerical experiments’ based on finite-element solutions of Maxwell's equations in a helicoidal frame. This article is part of the themed issue ‘Optical orbital angular momentum’. PMID:28069771

  5. Multi-slice spiral CT of aortocoronary grafts and internal mammary artery bypasses: Assessment of bypasses and their anastomoses; Mehrzeilen-Spiral-CT von aortokoronaren Venenbypaessen und Mammaria-interna-Bypaessen: Beurteilung der Bypaesse und ihrer Anastomosen

    Energy Technology Data Exchange (ETDEWEB)

    Froehner, S.; Wagner, M.; Schmitt, R.; Christopoulos, G.; Coblenz, G. [Inst. fuer Diagnostische und Interventionelle Radiologie, Herz- und Gefaessklinik GmbH, Bad Neustadt an der Saale (Germany); Brunn, J.; Mueller, M.; Kerber, S. [Fachbereich Kardiologie, Herz- und Gefaessklinik GmbH, Bad Neustadt an der Saale (Germany); Urbanski, P. [Klinik fuer Herzchirurgie, Herz- und Gefaessklinik GmbH, Bad Neustadt an der Saale (Germany)

    2002-07-01

    Objective: To assess aortocoronary grafts and internal mammary artery bypasses by means of EKG-triggered contrast-enhanced multi-slice spiral CT, and to evaluate the diagnostic accuracy of this new imaging modality. Material and methods: 59 patients with up to 5 aortocoronary grafts and/or internal mammary artery bypasses per patient were examined with regard to bypass morphology, the free passage, and the proximal as well as the distal anastomoses using multi-slice computed tomography. Axial source images were calculated by means of retrospective triggering at different diastolic delay times, and were postprocessed in several planes with the multiplanar volume reconstruction (MPVR) software. Results: On the pre-condition that data sets were acquired at sinus rhythm and at a heart rate lower than 65/min, aortocoronary grafts and internal mammary artery bypasses could be depicted in adequate diagnostic quality in about 80% of all cases with contrast-enhanced multi-slice spiral CT. Both, the free passage of the bypasses as well as the morphology of the proximal anastomoses were sufficiently assessed with multiplanar volume reconstruction (MPVR), whereas the distal anastomoses couldn't be depicted sufficiently in 20% of all cases. Conclusion: As a non-invasive method, contrast-enhanced and ECG-triggered multi-slice spiral computed tomography has gained diagnostic potential for the accurate visualization of aortocoronary grafts and the internal mammary artery bypasses. (orig.) [German] Ziel: Die vorliegende Arbeit stellt die Moeglichkeiten der kontrastmittelverstaerkten, EKG-getriggerten Mehrzeilen-Computertomographie in der Beurteilung von aortokoronaren Venenbypaessen und Mammaria-interna-Bypaessen dar. Material und Methode: Bei 59 Patienten mit 1 bis 5 aortokoronaren Venen-Bypaessen bzw. Mammaria-interna-Bypaessen wurden deren Morphologie, Durchgaengigkeit, die proximalen Anastomosen und die distalen Insertionsstellen mittels Mehrzeilen-Spiral-CT untersucht

  6. Technical Characteristics of a Novel Helical-Groove Traveling-Wave Tube Structure

    Science.gov (United States)

    Wallett, Thomas M.; Vaden, Karl R.; Freeman, Jon; Qureshi, A. Haq

    1998-01-01

    Experimental measurements of the dispersion characteristics of a C-band helix structure were carried out and compared to the dispersion characteristics found from a helix model using the three-dimensional electromagnetic computer code MAFIA. A conceptually novel design comprising a helical thread of the same pitch and inner diameter in a cylindrical waveguide also were calculated using the MAFIA code. The helical-groove structure exhibits a smaller bandwidth but at a much higher frequency range than the traditional helical structure for similar physical dimensions. It is physically more robust in construction. The interaction impedance also compares favorably with those of the conventional structure.

  7. Ideal, best packing, and energy minimizing double helices

    CERN Document Server

    O'Hara, Jun

    2011-01-01

    We study optimal double helices with straight axes (or the fattest tubes around them) computationally using three kinds of functionals; ideal ones using ropelength, best volume packing ones, and energy minimizers using two one-parameter families of interaction energies between two strands of types $r^{-\\alpha}$ and $\\frac1r\\exp(-kr)$. We compare the numerical results with experimental data of DNA.

  8. The Hemispheric Sign Rule of Current Helicity during the Rising Phase of Cycle 23

    Indian Academy of Sciences (India)

    S. D. Bao; G. X. Ai; H. Q. Zhang

    2000-09-01

    We compute the signs of two different current helicity parameters (i.e., best and ) for 87 active regions during the rise of cycle 23. The results indicate that 59% of the active regions in the northern hemisphere have negative best and 65% in the southern hemisphere have positive. This is consistent with that of the cycle 22. However, the helicity parameter shows a weaker opposite hemispheric preference in the new solar cycle. Possible reasons are discussed.

  9. Helical Aharonov-Casher edge states

    OpenAIRE

    Heremans, J. J.; Xu, L. L.

    2010-01-01

    It is shown that an Aharonov-Casher vector potential in a two-dimensional geometry can lead to helical edge states. The Aharonov-Casher vector potential is the electromagnetic dual of the magnetic vector potential, and leads to traveling states at the sample edge in analogy to the integer quantum Hall effect. The helical edge states are predicted to appear in a narrow channel geometry with parabolic or sufficiently symmetric confinement potential. The implications of the helical Aharonov-Cash...

  10. Employing Helicity Amplitudes for Resummation in SCET

    CERN Document Server

    Moult, Ian; Tackmann, Frank J; Waalewijn, Wouter J

    2016-01-01

    Helicity amplitudes are the fundamental ingredients of many QCD calculations for multi-leg processes. We describe how these can seamlessly be combined with resummation in Soft-Collinear Effective Theory (SCET), by constructing a helicity operator basis for which the Wilson coefficients are directly given in terms of color-ordered helicity amplitudes. This basis is crossing symmetric and has simple transformation properties under discrete symmetries.

  11. Diagnosis of lower gastrointestinal bleeding by multi-slice CT angiography: A meta-analysis.

    Science.gov (United States)

    He, Bosheng; Yang, Jushun; Xiao, Jing; Gu, Jinhua; Chen, Feixiang; Wang, Lin; Zhao, Chengjin; Qian, Junbo; Gong, Shenchu

    2017-08-01

    To estimate the diagnostic value of multi-slice spiral CT angiography (CTA) in lower gastrointestinal bleeding by a meta-analysis. The relevant clinical studies on the diagnostic value of CTA were searched on PubMed, Embase and other electronic documents databases with the deadline of 2016 September. Language was limited to English. A diagnostic meta-analysis was performed by using Meta-DiSc software. The effect sizes included sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), and diagnostic odds ratio (DOR) and 95% confidence interval (CI). The Cochran-Q test and I(2) statistic based on χ(2) test were used for estimation of the heterogeneity. Meta-regression was performed to explore the source of heterogeneity. SROC curve was established. A total of 14 articles including 549 patients with lower gastrointestinal bleeding were enrolled in the meta-analysis. The combined PLR, NLR and DOR were respectively 8.149, 0.158 and 56.213. There were significant heterogeneities in all estimations but we could not find the sources by meta-regression based on study design, study location, CT slices and sample size. The AUC and Q index under the fixed effect model was respectively 0.9463 and 0.8856. The multi-slice CTA has high diagnostic value for lower gastrointestinal bleeding. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Improved multislice calculations for including higher-order Laue zones effects

    Energy Technology Data Exchange (ETDEWEB)

    Lobato, I., E-mail: Ivan.Lobato@ua.ac.be [University of Antwerp, Department of Physics, Groenenborgerlaan 171, B-2020 Antwerp (Belgium); Van Dyck, D. [University of Antwerp, Department of Physics, Groenenborgerlaan 171, B-2020 Antwerp (Belgium)

    2012-08-15

    A new method for including higher-order Laue zones (HOLZs) effects in an efficient way in electron scattering simulations has been developed and tested by detail calculations. The calculated results by the conventional multislice (CMS) method and the improved conventional multislice (ICMS) method using a large dynamical aperture to avoid numerical errors are compared with accurate results. We have found that the zero-order Laue zones (ZOLZs) reflection cannot be properly described only using the projected potential in the whole unit cell; in general, we need to subslice the electrostatic potential inside the unit cell. It is shown that the ICMS method has higher accuracy than the CMS method for the calculation of the ZOLZ, HOLZ and Pseudo-HOLZ reflections. Hence, ICMS method allows to use a larger slice thickness than the CMS method and reduces the calculation time. -- Highlights: Black-Right-Pointing-Pointer We have developed and tested a new method for including HOLZ effects in an efficient way in electron scattering simulations. Black-Right-Pointing-Pointer The ICMS method has higher accuracy than the CMS method for the calculation of the ZOLZ, HOLZ and Pseudo-HOLZ reflections. Black-Right-Pointing-Pointer ICMS method allows to use a larger slice thickness than the CMS method and reduces the calculation time.

  13. The clinical application of multi-slice spiral CT angiography in abdominal aortic disease

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Objective: To evaluate the clinical application of multi-slice spiral CT angiography(MSCTA) in the assessment of abdominal aortic disease. Methods: Fifty-four patients underwent multi-slice spiral CT angiography of abdomen. Contrast agent (Omnipaque 300 I g/L) 1.5 ml/kg was injected and the injection rate was 3 ml/s. The delay time was determined by bolus tracking technique,Tll level abdominal aorta was set as the target vessel and the threshold was 180-200 Hu, slice width was 3 mm and with a pitch of 4-6.Original data were transferred to working-station to perform functional reconstruction. Results: Ten cases were normal, twenty-eight cases were abdominal aortic aneurysms, five abdominal aortic dissecting aneurysms (Debakay type Ⅲ ) and eleven aortic sclerosis. SSD showed the body of aneurysm and the relationship between aneurysm and adjacent blood vessel, MIP better displayed calcification of blood vessel wall and condition of the stent, MPR demonstrated true and false lumen, rupture site of abdominal aorta intima and mural thrombus. Conclusion: MSCTA axial and reconstruction image can show the extent of abdominal aortic disease and the relationship with adjacent blood vessels. It is a safe, simple and non-invasive examination method.

  14. Revisiting fermion helicity flip in Podolsky's Electromagnetism

    CERN Document Server

    Sales, Jorge Henrique; Thibes, Ronaldo

    2016-01-01

    The spin projection of a massive particle onto its direction of motion is called helicity (or "handedness"). It can therefore be positive or negative. When a particle's helicity changes from positive to negative (or vice-versa) due to its interaction with other particles or fields, we say there is a helicity flip. In this work we show that such helicity flip can be seen for an electron of $20 MeV$ of energy interacting with a charged scalar meson through the exchange of a virtual photon. This photon {\\it does not} necessarily need to be Podolsky's proposed photon; in fact, it is independent of it.

  15. Higher helicity invariants and solar dynamo

    Science.gov (United States)

    Sokolov, D. D.; Illarionov, E. A.; Akhmet'ev, P. M.

    2017-01-01

    Modern models of nonlinear dynamo saturation in celestial bodies (specifically, on the Sun) are largely based on the consideration of the balance of magnetic helicity. This physical variable has also a topological meaning: it is associated with the linking coefficient of magnetic tubes. In addition to magnetic helicity, magnetohydrodynamics has a number of topological integrals of motion (the so-called higher helicity moments). We have compared these invariants with magnetic helicity properties and concluded that they can hardly serve as nonlinear constraints on dynamo action.

  16. Decreased Diagnostic Accuracy of Multislice Coronary Computed Tomographic Angiography in Women with Atypical Angina Symptoms

    Directory of Open Access Journals (Sweden)

    Wen-Ying Jin

    2016-01-01

    Conclusions: Although MSCT is a reliable diagnostic modality for the exclusion of significant coronary artery stenoses in all patients, gender and atypical symptoms might have some influence on its diagnostic accuracy.

  17. Is multislice computed tomography an important tool for breast cancer staging and follow-up?

    Energy Technology Data Exchange (ETDEWEB)

    Miranda, Christiana Maia Nobre Rocha de; Santos, Carla Jotta Justo dos; Maranhao, Carol Pontes de Miranda, E-mail: maiachristiana@globo.com [Clinica de Medicina Nuclear e Radiologia de Maceio (MedRadiUS), Maceio, AL (Brazil); Farias, Lucas de Padua Gomes de; Padilha, Igor Gomes; Andrade, Anna Carolina de Mendonca de; Jatoba, Mayara Stephanie de Araujo [Faculdade de Medicina da Universidade Federal de Alagoas, Maceio, AL (Brazil)

    2012-03-15

    Breast cancer is the most common cancer in women and the leading cause of cancer death among the female population. Extramammary findings related to breast cancer play an important role in the prognosis and treatment of such entity and the correct diagnosis of such alterations is essential for increasing the chance of cure. Most of the times, such manifestations result from complications arising from treatment, and may be associated with lymph node involvement, locoregional recurrence or distant metastasis. (author)

  18. Fast multislice fluorescence molecular tomography using sparsity-inducing regularization.

    Science.gov (United States)

    Hejazi, Sedigheh Marjaneh; Sarkar, Saeed; Darezereshki, Ziba

    2016-02-01

    Fluorescence molecular tomography (FMT) is a rapidly growing imaging method that facilitates the recovery of small fluorescent targets within biological tissue. The major challenge facing the FMT reconstruction method is the ill-posed nature of the inverse problem. In order to overcome this problem, the acquisition of large FMT datasets and the utilization of a fast FMT reconstruction algorithm with sparsity regularization have been suggested recently. Therefore, the use of a joint L1/total-variation (TV) regularization as a means of solving the ill-posed FMT inverse problem is proposed. A comparative quantified analysis of regularization methods based on L1-norm and TV are performed using simulated datasets, and the results show that the fast composite splitting algorithm regularization method can ensure the accuracy and robustness of the FMT reconstruction. The feasibility of the proposed method is evaluated in an in vivo scenario for the subcutaneous implantation of a fluorescent-dye-filled capillary tube in a mouse, and also using hybrid FMT and x-ray computed tomography data. The results show that the proposed regularization overcomes the difficulties created by the ill-posed inverse problem.

  19. Fast multislice fluorescence molecular tomography using sparsity-inducing regularization

    Science.gov (United States)

    Hejazi, Sedigheh Marjaneh; Sarkar, Saeed; Darezereshki, Ziba

    2016-02-01

    Fluorescence molecular tomography (FMT) is a rapidly growing imaging method that facilitates the recovery of small fluorescent targets within biological tissue. The major challenge facing the FMT reconstruction method is the ill-posed nature of the inverse problem. In order to overcome this problem, the acquisition of large FMT datasets and the utilization of a fast FMT reconstruction algorithm with sparsity regularization have been suggested recently. Therefore, the use of a joint L1/total-variation (TV) regularization as a means of solving the ill-posed FMT inverse problem is proposed. A comparative quantified analysis of regularization methods based on L1-norm and TV are performed using simulated datasets, and the results show that the fast composite splitting algorithm regularization method can ensure the accuracy and robustness of the FMT reconstruction. The feasibility of the proposed method is evaluated in an in vivo scenario for the subcutaneous implantation of a fluorescent-dye-filled capillary tube in a mouse, and also using hybrid FMT and x-ray computed tomography data. The results show that the proposed regularization overcomes the difficulties created by the ill-posed inverse problem.

  20. Total anomalous connection of pulmonary veins to the portal vein. Value of multislice angiotomography. Report on three cases

    Directory of Open Access Journals (Sweden)

    Sara Alejandra Solórzano-Morales

    2014-07-01

    15 and 26% if all its varieties. Multislice angiotomography allows us to view the blood vessels and adjacent organs under consideration and obtain high-definition anatomic information. In the patients in this study, total anomalous connection of pulmonary veins to the portal vein was viewed with three-dimensional volumetric tomographic reconstructions and their correlation with ultrasonography studies.

  1. Role of multislice CT and magnetic resonance cholangiography in preoperative evaluation of potential donor in living related liver transplantation

    Directory of Open Access Journals (Sweden)

    Hossam M. Abdel-Rahman

    2016-03-01

    Conclusion: Multislice CT is a valuable tool in the evaluation of potential living liver donors that provides complete information on the hepatic vascular anatomy, the liver parenchyma, and volumetric measurements. MRC with a 3.0-T MR system demonstrates the preoperative biliary evaluation very well with a high accuracy rate.

  2. Helical coil thermal hydraulic model

    Science.gov (United States)

    Caramello, M.; Bertani, C.; De Salve, M.; Panella, B.

    2014-11-01

    A model has been developed in Matlab environment for the thermal hydraulic analysis of helical coil and shell steam generators. The model considers the internal flow inside one helix and its associated control volume of water on the external side, both characterized by their inlet thermodynamic conditions and the characteristic geometry data. The model evaluates the behaviour of the thermal-hydraulic parameters of the two fluids, such as temperature, pressure, heat transfer coefficients, flow quality, void fraction and heat flux. The evaluation of the heat transfer coefficients as well as the pressure drops has been performed by means of the most validated literature correlations. The model has been applied to one of the steam generators of the IRIS modular reactor and a comparison has been performed with the RELAP5/Mod.3.3 code applied to an inclined straight pipe that has the same length and the same elevation change between inlet and outlet of the real helix. The predictions of the developed model and RELAP5/Mod.3.3 code are in fairly good agreement before the dryout region, while the dryout front inside the helical pipes is predicted at a lower distance from inlet by the model.

  3. Segregation of helicity in inertial wave packets

    Science.gov (United States)

    Ranjan, A.

    2017-03-01

    Inertial waves are known to exist in the Earth's rapidly rotating outer core and could be important for the dynamo generation. It is well known that a monochromatic inertial plane wave traveling parallel to the rotation axis (along positive z ) has negative helicity while the wave traveling antiparallel (negative z ) has positive helicity. Such a helicity segregation, north and south of the equator, is necessary for the α2-dynamo model based on inertial waves [Davidson, Geophys. J. Int. 198, 1832 (2014), 10.1093/gji/ggu220] to work. The core is likely to contain a myriad of inertial waves of different wave numbers and frequencies. In this study, we investigate whether this characteristic of helicity segregation also holds for an inertial wave packet comprising waves with the same sign of Cg ,z, the z component of group velocity. We first derive the polarization relations for inertial waves and subsequently derive the resultant helicity in wave packets forming as a result of superposition of two or more waves. We find that the helicity segregation does hold for an inertial wave packet unless the wave numbers of the constituent waves are widely separated. In the latter case, regions of opposite color helicity do appear, but the mean helicity retains the expected sign. An illustration of this observation is provided by (a) calculating the resultant helicity for a wave packet formed by superposition of four upward-propagating inertial waves with different wave vectors and (b) conducting the direct numerical simulation of a Gaussian eddy under rapid rotation. Last, the possible effects of other forces such as the viscous dissipation, the Lorentz force, buoyancy stratification, and nonlinearity on helicity are investigated and discussed. The helical structure of the wave packet is likely to remain unaffected by dissipation or the magnetic field, but can be modified by the presence of linearly stable stratification and nonlinearity.

  4. Self-assembly of double helical nanostructures inside carbon nanotubes.

    Science.gov (United States)

    Lv, Cheng; Xue, Qingzhong; Shan, Meixia; Jing, Nuannuan; Ling, Cuicui; Zhou, Xiaoyan; Jiao, Zhiyong; Xing, Wei; Yan, Zifeng

    2013-05-21

    We use molecular dynamics (MD) simulations to show that a DNA-like double helix of two poly(acetylene) (PA) chains can form inside single-walled carbon nanotubes (SWNTs). The computational results indicate that SWNTs can activate and guide the self-assembly of polymer chains, allowing them to adopt a helical configuration in a SWNT through the combined action of the van der Waals potential well and the π-π stacking interaction between the polymer and the inner surface of SWNTs. Meanwhile both the SWNT size and polymer chain stiffness determine the outcome of the nanostructure. Furthermore, we also found that water clusters encourage the self-assembly of PA helical structures in the tube. This molecular model may lead to a better understanding of the formation of a double helix biological molecule inside SWNTs. Alternatively, it could form the basis of a novel nanoscale material by utilizing the 'empty' spaces of SWNTs.

  5. Glomus tumor of the gastric body:helical CT findings

    Institute of Scientific and Technical Information of China (English)

    HU Xiao-yun; HU Chun-hong; FANG Xiang-ming; ZHANG Tong-hua

    2007-01-01

    @@ Glomus tumors, also known as glomangiomas, are rare and originate in the neuromyoarterial glomus, a normal arteriovenous shunt which is abundantly supplied with nerve fibers and fulfills a temperature-regulating function. The classic location of glomus tumor is the subungual region, but the tumor can occur elsewhere in the skin, soft tissues, nerves, stomach, nasal cavity, and trachea.1 In the gastrointestinal (GI) tract the tumor occurs more often in the stomach than other parts, and typically occurs as a solitary submucosal nodule in the antrum.2 We reported a case of glomus tumor originating from the greater curvature of stomach which was studied with contrast-enhanced helical computed tomography (CT) and described the characteristic helical CT findings of the rare lesion.

  6. Magnetic Helicity and the Solar Dynamo

    Science.gov (United States)

    Canfield, Richard C.

    1997-01-01

    The objective of this investigation is to open a new window into the solar dynamo, convection, and magnetic reconnection through measurement of the helicity density of magnetic fields in the photosphere and tracing of large-scale patterns of magnetic helicity in the corona.

  7. The AGS synchrotron with four helical magnets

    Energy Technology Data Exchange (ETDEWEB)

    Tsoupas N.; Huang, H.; Roser, T.; MacKay, W.W.; Trbojevic, D.

    2012-05-20

    The idea of using two partial helical magnets was applied successfully to the AGS synchrotron to preserve the proton beam polarization. In this paper we explore in details the idea of using four helical magnets placed symmetrically in the AGS ring. The placement of four helical magnets in the AGS ring provides many advantages over the present setup of the AGS which uses two partial helical magnets. First, the symmetric placement of the four helical magnets allows for a better control of the AGS optics with reduced values of the beta functions especially near beam injection, second, the vertical spin direction during beam injection and extraction is closer to vertical, and third, it provides for a larger 'spin tune gap', which allows the vertical and horizontal tunes to be placed, and prevent the horizontal and vertical intrinsic spin resonances of the AGS to occur during the acceleration cycle. Although the same spin gap can be obtained with a single or two partial helices, the required high field strength of a single helix makes its use impractical, and that of the double helix rather difficult. In this paper we will provide results on the spin tune and on the optics of the AGS with four partial helical magnets, and compare these results with the present setup of the AGS that uses two partial helical magnets.

  8. Helical Magnetic Fields in AGN Jets

    Indian Academy of Sciences (India)

    Y. J. Chen; G.-Y. Zhao; Z.-Q. Shen

    2014-09-01

    We establish a simple model to describe the helical magnetic fields in AGN jets projected on the sky plane and the line-of-sight. This kind of profile has been detected in the polarimetric VLBI observation of many blazar objects, suggesting the existence of helical magnetic fields in these sources.

  9. Helical chirality induction of expanded porphyrin analogues

    Indian Academy of Sciences (India)

    Jun-Ichiro Setsune

    2012-11-01

    Expanded porphyrin analogues with unique figure-eight conformation were prepared by way of useful pyrrole intermediates such as bis(azafulvene)s and 2-borylpyrrole. Supramolecular chirogenesis of cyclooctapyrrole O1 with 32-cycloconjugation was successfully applied to determine absolute configuration of chiral carboxylic acids. Dinuclear CuII complex of cyclooctapyrrole O2 with interrupted -conjugation was resolved by HPLC into enantiomers and their helical handedness was determined by theoretical simulation of their CD spectral pattern. Enantioselective induction of helicity in the metal helicate formation in the presence of a chiral promoter was demonstrated by using ()-(+)-1-(1-phenyl)ethylamine that favoured , helicity. Dinuclear CoII complexes of cyclotetrapyrroletetrapyridine O3 were found to be substitution labile and pick up amino acid anions in water. Those amino acid complexes of O3Co2 were rendered to adopt a particular unidirectional helical conformation preferentially depending on the ligated amino acid anion.

  10. Solubilization and fractionation of paired helical filaments.

    Science.gov (United States)

    González, P J; Correas, I; Avila, J

    1992-09-01

    Paired helical filaments isolated from brains of two different patients with Alzheimer's disease were extensively treated with the ionic detergent, sodium dodecyl sulphate. Filaments were solubilized at different extents, depending on the brain examined, thus suggesting the existence of two types of paired helical filaments: sodium dodecyl sulphate-soluble and insoluble filaments. In the first case, the number of structures resembling paired helical filaments greatly decreased after the detergent treatment, as observed by electron microscopy. Simultaneously, a decrease in the amount of sedimentable protein was also observed upon centrifugation of the sodium dodecyl sulfate-treated paired helical filaments. A sodium dodecyl sulphate-soluble fraction was isolated as a supernatant after low-speed centrifugation of the sodium dodecyl sulphate-treated paired helical filaments. The addition of the non-ionic detergent Nonidet-P40 to this fraction resulted in the formation of paired helical filament-like structures. When the sodium dodecyl sulphate-soluble fraction was further fractionated by high-speed centrifugation, three subfractions were observed: a supernatant, a pellet and a thin layer between these two subfractions. No paired helical filaments were observed in any of these subfractions, even after addition of Nonidet P-40. However, when they were mixed back together, the treatment with Nonidet P-40 resulted in the visualization of paired helical filament-like structures. These results suggest that at least two different components are needed for the reconstitution of paired helical filaments as determined by electron microscopy. The method described here may allow the study of the components involved in the formation of paired helical filaments and the identification of possible factors capable of blocking this process.

  11. Cationic Nitrogen Doped Helical Nanographenes.

    Science.gov (United States)

    Xu, Kun; Feng, Xinliang; Berger, Reinhard; Popov, Alexey A; Weigand, Jan J; Vincon, Ilka; Machata, Peter; Hennersdorf, Felix; Zhou, Youjia; Fu, Yubin

    2017-09-13

    Herein, we report on the synthesis of a series of novel cationic nitrogen doped nanographenes (CNDN) by rhodium catalyzed annulation reactions. This powerful method allows for the synthesis of cationic nanographenes with non-planar, axial chiral geometries. Single-crystal X-ray analysis reveals helical and cove-edged structures. Compared to their all-carbon analogues, the CNDN exhibit energetically lower lying frontier orbitals with a reduced optical energy gap and an electron accepting behavior. All derivatives show quasi reversible reductions in cyclic voltammetry. Depending on the number of nitrogen dopant, in situ spectroelectrochemistry proves the formation of neutral radicals (one nitrogen dopant) or radical cations (two nitrogen dopants) upon reduction. The developed synthetic protocol paves the way for the design and synthesis of expanded nanographenes or even graphene nanoribbons containing cationic nitrogen doping. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Formation of helical ion chains

    CERN Document Server

    Nigmatullin, Ramil; De Chiara, Gabriele; Morigi, Giovanna; Plenio, Martin B; Retzker, Alex

    2011-01-01

    We study the nonequilibrium dynamics of the linear to zigzag structural phase transition exhibited by an ion chain confined in a trap with periodic boundary conditions. The transition is driven by reducing the transverse confinement at a finite quench rate, which can be accurately controlled. This results in the formation of zigzag domains oriented along different transverse planes. The twists between different domains can be stabilized by the topology of the trap and under laser cooling the system relaxes to a helical chain with possibly nonzero winding number. Molecular dynamics simulations are used to obtain a large sample of possible trajectories for different quench rates. The scaling of the average winding number with different quench rates is compared to the prediction of the Kibble-Zurek theory, and a good quantitative agreement is found.

  13. Best packing of identical helices

    Science.gov (United States)

    Huh, Youngsik; Hong, Kyungpyo; Kim, Hyoungjun; No, Sungjong; Oh, Seungsang

    2016-10-01

    In this paper we prove the unique existence of a ropelength-minimizing conformation of the θ-spun double helix in a mathematically rigorous way, and find the minimal ropelength {{{Rop}}}* (θ )=-\\tfrac{8π }{t} where t is the unique solution in [-θ ,0] of the equation 2-2\\cos (t+θ )={t}2. Using this result, the pitch angles of the standard, triple and quadruple helices are around 39.3771^\\circ , 42.8354^\\circ and 43.8351^\\circ , respectively, which are almost identical with the approximated pitch angles of the zero-twist structures previously known by Olsen and Bohr. We also find the ropelength of the standard N-helix.

  14. Imaging patients with renal colic: a comparative analysis of the impact of non-contrast helical computed tomography versus intravenous pyelography on the speed of patient processing in the Emergency Department.

    LENUS (Irish Health Repository)

    Quirke, M

    2011-03-01

    Introduction Non-contrast helical CT (NHCT) became the procedure of choice for investigating Emergency Department (ED) patients presenting with suspected renal colic at Beaumont Hospital, Dublin, in 2008. The impact of NHCT on waiting times and patient management was compared with intravenous pyelography (IVP). Methods A retrospective, comparative cohort analysis of 95 patients who had IVP and 109 patients who had NHCT was performed. Length of ED stay from time of scan ordering to referral or discharge was analysed relative to time of day and scan result. Results Patients having NHCT who attended between 00:00-08:00 h, had a twofold longer length of stay than those who had IVP between the same hours (median 7.07 h vs 3.03 h, p=0.0294). The length of ED stay for patients attending between 08:00 and 24:00 h was similar in both groups. The presence of urolithiasis did not impact on length of stay. A significant alternate\\/incidental diagnosis was reported in 28 patients having NHCT, of which 12 were cancerous growths. Conclusion NHCT allows for the detection of incidental\\/alternate diagnoses that may not be otherwise detected in patients with renal colic. Compared to IVP, NHCT has not impacted positively on the speed of patient processing in the ED under study. For patients presenting after midnight, it is associated with over a twofold longer length of stay from the time of scan ordering to referral or discharge. This leads to prolonged patient stays in the ED, and as such contributes to overcrowding.

  15. Imaging patients with renal colic: a comparative analysis of the impact of non-contrast helical computed tomography versus intravenous pyelography on the speed of patient processing in the Emergency Department.

    LENUS (Irish Health Repository)

    Quirke, M

    2012-02-01

    INTRODUCTION: Non-contrast helical CT (NHCT) became the procedure of choice for investigating Emergency Department (ED) patients presenting with suspected renal colic at Beaumont Hospital, Dublin, in 2008. The impact of NHCT on waiting times and patient management was compared with intravenous pyelography (IVP). METHODS: A retrospective, comparative cohort analysis of 95 patients who had IVP and 109 patients who had NHCT was performed. Length of ED stay from time of scan ordering to referral or discharge was analysed relative to time of day and scan result. RESULTS: Patients having NHCT who attended between 00:00-08:00 h, had a twofold longer length of stay than those who had IVP between the same hours (median 7.07 h vs 3.03 h, p=0.0294). The length of ED stay for patients attending between 08:00 and 24:00 h was similar in both groups. The presence of urolithiasis did not impact on length of stay. A significant alternate\\/incidental diagnosis was reported in 28 patients having NHCT, of which 12 were cancerous growths. CONCLUSION: NHCT allows for the detection of incidental\\/alternate diagnoses that may not be otherwise detected in patients with renal colic. Compared to IVP, NHCT has not impacted positively on the speed of patient processing in the ED under study. For patients presenting after midnight, it is associated with over a twofold longer length of stay from the time of scan ordering to referral or discharge. This leads to prolonged patient stays in the ED, and as such contributes to overcrowding.

  16. Multi-Slice Magnetic Resonance Imaging with the Dynamic Multi-Coil Technique

    Science.gov (United States)

    Juchem, Christoph; Nahhass, Omar M.; Nixon, Terence W.; de Graaf, Robin A.

    2015-01-01

    To date, spatial encoding for MRI is based on linear X, Y and Z field gradients generated by dedicated X, Y and Z wire patterns. We recently introduced the Dynamic Multi-Coil Technique (DYNAMITE) for the generation of magnetic field shapes for biomedical MR applications from a set of individually driven localized coils. The benefits for B0 magnetic field homogenization have been shown as well as proof-of-principle of radial and algebraic MRI. In this study the potential of DYNAMITE MRI is explored further and the first multi-slice MRI implementation is presented in which all gradient fields are purely DYNAMITE-based. The obtained image fidelity is shown to be virtually identical to a conventional MRI system with dedicated X, Y and Z gradient coils. Comparable image quality is a milestone towards the establishment of fully functional DYNAMITE MRI (and shim) systems. PMID:26419649

  17. A simultaneous multi-slice selective J-resolved experiment for fully resolved scalar coupling information

    Science.gov (United States)

    Zeng, Qing; Lin, Liangjie; Chen, Jinyong; Lin, Yanqin; Barker, Peter B.; Chen, Zhong

    2017-09-01

    Proton-proton scalar coupling plays an important role in molecular structure elucidation. Many methods have been proposed for revealing scalar coupling networks involving chosen protons. However, determining all JHH values within a fully coupled network remains as a tedious process. Here, we propose a method termed as simultaneous multi-slice selective J-resolved spectroscopy (SMS-SEJRES) for simultaneously measuring JHH values out of all coupling networks in a sample within one experiment. In this work, gradient-encoded selective refocusing, PSYCHE decoupling and echo planar spectroscopic imaging (EPSI) detection module are adopted, resulting in different selective J-edited spectra extracted from different spatial positions. The proposed pulse sequence can facilitate the analysis of molecular structures. Therefore, it will interest scientists who would like to efficiently address the structural analysis of molecules.

  18. Multi-slice MRI with the dynamic multi-coil technique.

    Science.gov (United States)

    Juchem, Christoph; Nahhass, Omar M; Nixon, Terence W; de Graaf, Robin A

    2015-11-01

    To date, spatial encoding for MRI is based on linear X, Y and Z field gradients generated by dedicated X, Y and Z wire patterns. We recently introduced the dynamic multi-coil technique (DYNAMITE) for the generation of magnetic field shapes for biomedical MR applications from a set of individually driven localized coils. The benefits for B0 magnetic field homogenization have been shown, as well as proof of principle of radial and algebraic MRI. In this study the potential of DYNAMITE MRI is explored further and the first multi-slice MRI implementation in which all gradient fields are purely DYNAMITE based is presented. The obtained image fidelity is shown to be virtually identical to that of a conventional MRI system with dedicated X, Y and Z gradient coils. Comparable image quality is a milestone towards the establishment of fully functional DYNAMITE MRI (and shim) systems.

  19. Large-scale instabilities of helical flows

    CERN Document Server

    Cameron, Alexandre; Brachet, Marc-Étienne

    2016-01-01

    Large-scale hydrodynamic instabilities of periodic helical flows are investigated using $3$D Floquet numerical computations. A minimal three-modes analytical model that reproduce and explains some of the full Floquet results is derived. The growth-rate $\\sigma$ of the most unstable modes (at small scale, low Reynolds number $Re$ and small wavenumber $q$) is found to scale differently in the presence or absence of anisotropic kinetic alpha (\\AKA{}) effect. When an $AKA$ effect is present the scaling $\\sigma \\propto q\\; Re\\,$ predicted by the $AKA$ effect theory [U. Frisch, Z. S. She, and P. L. Sulem, Physica D: Nonlinear Phenomena 28, 382 (1987)] is recovered for $Re\\ll 1$ as expected (with most of the energy of the unstable mode concentrated in the large scales). However, as $Re$ increases, the growth-rate is found to saturate and most of the energy is found at small scales. In the absence of \\AKA{} effect, it is found that flows can still have large-scale instabilities, but with a negative eddy-viscosity sca...

  20. Helical Screw Expander Evaluation Project. Final report

    Energy Technology Data Exchange (ETDEWEB)

    McKay, R.

    1982-03-01

    A functional 1-MW geothermal electric power plant that featured a helical screw expander was produced and then tested in Utah in 1978 to 1979 with a demonstrated average performance of approximately 45% machine efficiency over a wide range of test conditions in noncondensing operation on two-phase geothermal fluids. The Project also produced a computer-equipped data system, an instrumentation and control van, and a 1000-kW variable load bank, all integrated into a test array designed for operation at a variety of remote test sites. Additional testing was performed in Mexico in 1980 under a cooperative test program using the same test array, and machine efficiency was measured at 62% maximum with the rotors partially coated with scale, compared with approximately 54% maximum in Utah with uncoated rotors, confirming the importance of scale deposits within the machine on performance. Data are presented for the Utah testing and for the noncondensing phases of the testing in Mexico. Test time logged was 437 hours during the Utah tests and 1101 hours during the Mexico tests.

  1. Towards online patient imaging during helical radiotherapy.

    Science.gov (United States)

    Yu, L; Poole, C M; Lancaster, C M; Sylvander, S R

    2015-03-01

    Exit-detector data from helical radiation therapy have been studied extensively for delivery verification and dose reconstruction. Since the same radiation source is used for both imaging and treatment, this work investigates the possibility of utilising exit-detector raw data for imaging purposes. This gives rise to potential clinical applications such as retrospective daily setup verification and inter-fractional setup error detection. The exit-detector raw data were acquired and independently analysed using Python programming language. The raw data were extracted from the treatment machine's onboard computer, and converted into 2D array files. The contours of objects (phantom or patient) were acquired by applying a logarithmic function to the ratio of two sinograms, one with the object in the beam and one without. The setup variation between any two treatment deliveries can be detected by applying the same function to their corresponding exit-detector sinograms. The contour of the object was well defined by the secondary radiation from the treatment beam and validated with the imaging beam, although no internal structures were discernible due to the interference from the primary radiation. The sensitivity of the setup variation detection was down to 2 mm, which was mainly limited by the resolution of the exit-detector itself. The exit-detector data from treatment procedures contain valuable photon exit fluence maps which can be utilised for contour definition and verification of patient alignment without reconstruction.

  2. Magnetic Helicity in a Cyclic Convective Dynamo

    Science.gov (United States)

    Miesch, Mark S.; Zhang, Mei; Augustson, Kyle C.

    2016-05-01

    Magnetic helicity is a fundamental agent for magnetic self-organization in magnetohydrodynamic (MHD) dynamos. As a conserved quantity in ideal MHD, it establishes a strict topological coupling between large and small-scale magnetic fields. The generation of magnetic fields on scales larger than the velocity field is linked to an upscale transfer of magnetic helicity, either locally in spectral space as in the inverse cascade of magnetic helicity in MHD turbulence or non-locally, as in the turbulent alpha-effect of mean-field dynamo theory. Thus, understanding the generation, transport, and dissipation of magnetic helicity is an essential prerequisite to understanding manifestations of magnetic self-organization in the solar dynamo, including sunspots, the prominent dipole and quadrupole moments, and the 22-year magnetic activity cycle. We investigate the role of magnetic helicity in a convective dynamo model that exhibits regular magnetic cycles. The cycle is marked by coherent bands of toroidal field that persist within the convection zone and that are antisymmetric about the equator. When these toriodal bands interact across the equator, it initiates a global restructuring of the magnetic topology that contributes to the reversal of the dipole moment. Thus, the polar field reversals are preceeded by a brief reversal of the subsurface magnetic helicity. There is some evidence that the Sun may exhibit a similar magnetic helicity reversal prior to its polar field reversals.

  3. Bootstrapping One-Loop QCD Amplitudeswith General Helicities

    Energy Technology Data Exchange (ETDEWEB)

    Berger, Carola F.; Bern, Zvi; Dixon, Lance J.; Forde, Darren; Kosower, David A.

    2006-04-25

    The recently developed on-shell bootstrap for computing one-loop amplitudes in non-supersymmetric theories such as QCD combines the unitarity method with loop-level on-shell recursion. For generic helicity configurations, the recursion relations may involve undetermined contributions from non-standard complex singularities or from large values of the shift parameter. Here we develop a strategy for sidestepping difficulties through use of pairs of recursion relations. To illustrate the strategy, we present sets of recursion relations needed for obtaining n-gluon amplitudes in QCD. We give a recursive solution for the one-loop n-gluon QCD amplitudes with three or four color-adjacent gluons of negative helicity and the remaining ones of positive helicity. We provide an explicit analytic formula for the QCD amplitude A{sub 6;1}(1{sup -}, 2{sup -}, 3{sup -}, 4{sup +}, 5{sup +}, 6{sup +}), as well as numerical results for A{sub 7;1}(1{sup -}, 2{sup -}, 3{sup -}, 4{sup +}, 5{sup +}, 6{sup +}, 7{sup +}), A{sub 8;1}(1{sup -}, 2{sup -}, 3{sup -}, 4{sup +}, 5{sup +}, 6{sup +}, 7{sup +}, 8{sup +}), and A{sub 8;1}(1{sup -}, 2{sup -}, 3{sup -}, 4{sup -}, 5{sup +}, 6{sup +}, 7{sup +}, 8{sup +}). We expect the on-shell bootstrap approach to have widespread applications to phenomenological studies at colliders.

  4. Single Band Helical Antenna in Axial Mode

    Directory of Open Access Journals (Sweden)

    Parminder Singh

    2012-11-01

    Full Text Available Helical antennas have been widely used in a various useful applications, due to their low weight and low profile conformability, easy and cheap realization.Radiation properties of this antenna are examined both theoretically and experimentally. In this paper, an attempt has been made to investigate new helical antenna structure for Applications. CST MWS Software is used for the simulation and design calculations of the helical antennas. The axial ratio, return loss, VSWR, Directivity, gain, radiation pattern is evaluated. Using CST MWS simulation software proposed antenna is designed/simulated and optimized. The antenna exhibits a single band from 0 GHz to 3 GHz for GPS and several satellite applications

  5. Analysis on two novel spherical helical antennas

    Institute of Scientific and Technical Information of China (English)

    Hou ZHANG; Yingzeng YIN; Dongyu XIA

    2009-01-01

    Two novel spherical helical antennas are designed by projecting the planar equiangular spiral antenna onto hemisphere and partial sphere surfaces.Their radiation properties are analyzed by the moment method with curved basis and test function,and the curves of the voltage standing wave ratio (VSWR),gain,polarization and pattern that change with frequency are also given,respectively.It can be seen that the circular polarization band of the novel hemispherical helical antenna is broader.The gain curve of the partial spherical helical antenna is flatter and the structure is simpler.

  6. Investigation of backfire monofilar helical antenna

    DEFF Research Database (Denmark)

    Smith, Thomas Gunst; Larsen, Niels Vesterdal; Gothelf, Ulrich Vesterager

    2011-01-01

    This paper presents a numerical investigation of the electromagnetic properties of the backfire monofilar helical antenna. The current distribution along the helical conductor, the input impedance, and the front-to-back ratio are calculated and analyzed for the backfire operation of the antenna....... A parametric study of the helical geometry and the resulting antenna characteristics will be described and discussed. The currents and fields are calculated using the simulation software AWAS based on the Method of Moments with a wire representation of the ground plane....

  7. Transmembrane helices in "classical" nuclear reproductive steroid receptors: a perspective.

    Science.gov (United States)

    Morrill, Gene A; Kostellow, Adele B; Gupta, Raj K

    2015-01-01

    Steroid receptors of the nuclear receptor superfamily are proposed to be either: 1) located in the cytosol and moved to the cell nucleus upon activation, 2) tethered to the inside of the plasma membrane, or 3) retained in the nucleus until free steroid hormone enters and activates specific receptors. Using computational methods to analyze peptide receptor topology, we find that the "classical" nuclear receptors for progesterone (PRB/PGR), androgen (ARB/AR) and estrogen (ER1/ESR1) contain two transmembrane helices (TMH) within their ligand-binding domains (LBD).The MEMSAT-SVM algorithm indicates that ARB and ER2 (but not PRB or ER1) contain a pore-lining (channel-forming) region which may merge with other pore-lining regions to form a membrane channel. ER2 lacks a TMH, but contains a single pore-lining region. The MemBrain algorithm predicts that PRB, ARB and ER1 each contain one TMH plus a half TMH separated by 51 amino acids.ER2 contains two half helices. The TM-2 helices of ARB, ER1 and ER2 each contain 9-13 amino acid motifs reported to translocate the receptor to the plasma membrane, as well as cysteine palmitoylation sites. PoreWalker analysis of X-ray crystallographic data identifies a pore or channel within the LBDs of ARB and ER1 and predicts that 70 and 72 residues are pore-lining residues, respectively. The data suggest that (except for ER2), cytosolic receptors become anchored to the plasma membrane following synthesis. Half-helices and pore-lining regions in turn form functional ion channels and/or facilitate passive steroid uptake into the cell. In perspective, steroid-dependent insertion of "classical" receptors containing pore-lining regions into the plasma membrane may regulate permeability to ions such as Ca(2+), Na(+) or K(+), as well as facilitate steroid translocation into the nucleus.

  8. COMPUTING

    CERN Multimedia

    M. Kasemann

    Overview In autumn the main focus was to process and handle CRAFT data and to perform the Summer08 MC production. The operational aspects were well covered by regular Computing Shifts, experts on duty and Computing Run Coordination. At the Computing Resource Board (CRB) in October a model to account for service work at Tier 2s was approved. The computing resources for 2009 were reviewed for presentation at the C-RRB. The quarterly resource monitoring is continuing. Facilities/Infrastructure operations Operations during CRAFT data taking ran fine. This proved to be a very valuable experience for T0 workflows and operations. The transfers of custodial data to most T1s went smoothly. A first round of reprocessing started at the Tier-1 centers end of November; it will take about two weeks. The Computing Shifts procedure was tested full scale during this period and proved to be very efficient: 30 Computing Shifts Persons (CSP) and 10 Computing Resources Coordinators (CRC). The shift program for the shut down w...

  9. [Role of cone-beam computed tomography in diagnostic otorhinolaryngological imaging].

    Science.gov (United States)

    Perényi, Ádám; Bella, Zsolt; Baráth, Zoltán; Magyar, Péter; Nagy, Katalin; Rovó, László

    2016-01-10

    Accurate diagnosis and preoperative planning in modern otorhinolaryngology is strongly supported by imaging with enhanced visualization. Computed tomography is often used to examine structures within bone frameworks. Given the hazards of ionizing radiation, repetitive imaging studies exponentially increase the risk of damages to radiosensitive tissues. The authors compare multislice and cone-beam computed tomography and determine the role, advantages and disadvantages of cone-beam computed tomography in otorhinolaryngological imaging. They summarize the knowledge from the international literature and their individual imaging studies. They conclude that cone-beam computed tomography enables high-resolution imaging and reconstruction in any optional plane and in space with considerably lower effective radiation dose. Cone-beam computed tomography with appropriate indications proved to be an excellent diagnostic tool in otorhinolaryngological imaging. It makes an alternative to multislice computed tomography and it is an effective tool in perioperative and postoperative follow-up, especially in those cases which necessitate repetitive imaging with computed tomography.

  10. Association of maxillary sinus mucosa thickness with dental root apex:a retrospective helical computed tomographic study%牙源性上颌窦炎中窦腔黏膜增厚与牙根尖关联螺旋CT研究

    Institute of Scientific and Technical Information of China (English)

    孙艺渊; 王珮华; 范新东

    2014-01-01

    Objective To evaluate the association of sinus mucosal thickness with dental root apex intruding into the cavity of maxillary sinus or not among patients with odontogenic maxillary sinusitis on helical computed tomographic image. Method A retrospective study was carried out among 52 patients (104 sides) with odontogenic maxillary sinusitis, received helical computed tomography imaging to paranasal sinus to analyze the association if dental root apex being intruding into sinus cavity with sinus mucosal thickness in case of odontogenic maxillary sinusitis. Result In this group of cases, 58 sides (55.7%) were identified, based on the images, with dental root apex intruding into the cavity of maxillary sinus, and among these involved sinus, 46 sides (79.3%) were found with a local mucosal thickness thickened more than 2 mm. The thickness of cases with root apex intruding into the cavity of maxillary sinus was (7.76±8.39 mm), significantly thicker than that (3.17±4.14 mm) of cases without root apex intruding into the cavity of sinus (P=0.001). Conclusions As shown on helical computed tomographic images, cases with odontogenic maxillary sinusitis will have obviously thickened sinus mucosa, with its development and severity positively associated with the presence of dental root apex intruding into maxillary sinus.%目的:探讨牙根尖是否突入上颌窦与牙源性上颌窦炎患者窦腔黏膜厚度之间的CT影像学关联性。方法回顾性分析牙源性上颌窦炎患者52例(104侧)的螺旋CT影像学资料,评估上颌窦黏膜厚度与牙根尖是否突入上颌窦窦腔的关系。结果本组患者检出58侧(55.7%)有牙根尖突入窦腔,其中46侧(79.3%)存在上颌窦局部黏膜增厚大于2mm。牙根突入窦腔的上颌窦黏膜厚度(7.76±8.39mm)和无牙根突入窦腔的黏膜厚度(3.17±4.14mm)组间差异统计学意义显著(P=0.001)。结论螺旋CT影像提示,牙源性上颌窦炎患者上颌窦黏

  11. COMPUTING

    CERN Multimedia

    M. Kasemann

    Overview During the past three months activities were focused on data operations, testing and re-enforcing shift and operational procedures for data production and transfer, MC production and on user support. Planning of the computing resources in view of the new LHC calendar in ongoing. Two new task forces were created for supporting the integration work: Site Commissioning, which develops tools helping distributed sites to monitor job and data workflows, and Analysis Support, collecting the user experience and feedback during analysis activities and developing tools to increase efficiency. The development plan for DMWM for 2009/2011 was developed at the beginning of the year, based on the requirements from the Physics, Computing and Offline groups (see Offline section). The Computing management meeting at FermiLab on February 19th and 20th was an excellent opportunity discussing the impact and for addressing issues and solutions to the main challenges facing CMS computing. The lack of manpower is particul...

  12. COMPUTING

    CERN Multimedia

    I. Fisk

    2011-01-01

    Introduction CMS distributed computing system performed well during the 2011 start-up. The events in 2011 have more pile-up and are more complex than last year; this results in longer reconstruction times and harder events to simulate. Significant increases in computing capacity were delivered in April for all computing tiers, and the utilisation and load is close to the planning predictions. All computing centre tiers performed their expected functionalities. Heavy-Ion Programme The CMS Heavy-Ion Programme had a very strong showing at the Quark Matter conference. A large number of analyses were shown. The dedicated heavy-ion reconstruction facility at the Vanderbilt Tier-2 is still involved in some commissioning activities, but is available for processing and analysis. Facilities and Infrastructure Operations Facility and Infrastructure operations have been active with operations and several important deployment tasks. Facilities participated in the testing and deployment of WMAgent and WorkQueue+Request...

  13. COMPUTING

    CERN Multimedia

    P. McBride

    The Computing Project is preparing for a busy year where the primary emphasis of the project moves towards steady operations. Following the very successful completion of Computing Software and Analysis challenge, CSA06, last fall, we have reorganized and established four groups in computing area: Commissioning, User Support, Facility/Infrastructure Operations and Data Operations. These groups work closely together with groups from the Offline Project in planning for data processing and operations. Monte Carlo production has continued since CSA06, with about 30M events produced each month to be used for HLT studies and physics validation. Monte Carlo production will continue throughout the year in the preparation of large samples for physics and detector studies ramping to 50 M events/month for CSA07. Commissioning of the full CMS computing system is a major goal for 2007. Site monitoring is an important commissioning component and work is ongoing to devise CMS specific tests to be included in Service Availa...

  14. Anomalous origin of coronary artery: the role of multislice CT Angiography: a case report and literature review

    Energy Technology Data Exchange (ETDEWEB)

    Rabelo, Daniel Rocha; Barros, Marcio Vinicius Lins; Nunes, Maria do Carmo Pereira; Siqueira, Maria Helena Albernaz, E-mail: marciovlbarros@uol.com.br [Hospital Mater Dei, Belo Horizonte, MG (Brazil)

    2012-07-15

    Anomalous origin of coronary arteries is a relatively rare entity and can present different clinical forms. Recently, CT angiography of the coronary arteries have demonstrated an important role in the diagnosis and management of these anomalies. We present the case of a young female without significant comorbidities who presented with cardiopulmonary arrest, being revived by a team of customer service mobile emergency. After completion of multislice CT angiography of the coronary arteries was observed anomalous origin of left main coronary artery in the right coronary artery, no signs of extrinsic compression. Patient received a defibrillator and had an uneventful follow-up performed. Multislice CT angiography is minimally invasive diagnostic methods to detect the origin and trajectory of the coronary arteries, allowing an alternative to cardiac catheterization for evaluation of patients with anomalous origin of coronary arteries. (author)

  15. All One-loop Maximally Helicity Violating Gluonic Amplitudes in QCD

    Energy Technology Data Exchange (ETDEWEB)

    Berger, Carola F.; Bern, Zvi; Dixon, Lance J.; Forde, Darren; Kosower, David A.

    2006-07-05

    We use on-shell recursion relations to compute analytically the one-loop corrections to maximally-helicity-violating n-gluon amplitudes in QCD. The cut-containing parts have been computed previously; our work supplies the remaining rational parts for these amplitudes, which contain two gluons of negative helicity and the rest positive, in an arbitrary color ordering. We also present formulae specific to the six-gluon cases, with helicities (-+-+++) and (-++-++), as well as numerical results for six, seven, and eight gluons. Our construction of the n-gluon amplitudes illustrates the relatively modest growth in complexity of the on-shell-recursive calculation as the number of external legs increases. These amplitudes add to the growing body of one-loop amplitudes known for all n, which are useful for studies of general properties of amplitudes, including their twistor-space structure.

  16. Shielding requirements in helical tomotherapy

    Science.gov (United States)

    Baechler, S.; Bochud, F. O.; Verellen, D.; Moeckli, R.

    2007-08-01

    Helical tomotherapy is a relatively new intensity-modulated radiation therapy (IMRT) treatment for which room shielding has to be reassessed for the following reasons. The beam-on-time needed to deliver a given target dose is increased and leads to a weekly workload of typically one order of magnitude higher than that for conventional radiation therapy. The special configuration of tomotherapy units does not allow the use of standard shielding calculation methods. A conventional linear accelerator must be shielded for primary, leakage and scatter photon radiations. For tomotherapy, primary radiation is no longer the main shielding issue since a beam stop is mounted on the gantry directly opposite the source. On the other hand, due to the longer irradiation time, the accelerator head leakage becomes a major concern. An analytical model based on geometric considerations has been developed to determine leakage radiation levels throughout the room for continuous gantry rotation. Compared to leakage radiation, scatter radiation is a minor contribution. Since tomotherapy units operate at a nominal energy of 6 MV, neutron production is negligible. This work proposes a synthetic and conservative model for calculating shielding requirements for the Hi-Art II TomoTherapy unit. Finally, the required concrete shielding thickness is given for different positions of interest.

  17. Helical Two-Revolutional Cyclical Surface

    Directory of Open Access Journals (Sweden)

    Tatiana Olejníková

    2009-12-01

    Full Text Available Paper presents a family of helical two-revolutional cyclical surfaces, which arecreated by movement of the circle alongside the helical cycloidal curve, where circle islocated in the curve normal plane and its centre is on this curve. Helical cycloidal curvecan be created by simultaneous revolution of a point about two different axes 3o, 2o and byscrewing about axis 1o in the space. Form of the helical cycloidal curve and also of thehelical two-revolutional cyclical surface is dependent on the relative position of the threeaxes of revolutions, on multiples of angular velocities and orientations of separaterevolutions. Analytic representation, classification of surfaces and some of their geometricproperties are derived.

  18. Helicity at Photospheric and Chromospheric Heights

    CERN Document Server

    Tiwari, S K; Sankarasubramanian, K

    2009-01-01

    In the solar atmosphere the twist parameter $\\alpha$ has the same sign as magnetic helicity. It has been observed using photospheric vector magnetograms that negative/positive helicity is dominant in the northern/southern hemisphere of the Sun. Chromospheric features show dextral/sinistral dominance in the northern/southern hemisphere and sigmoids observed in X-rays also have a dominant sense of reverse-S/forward-S in the northern/southern hemisphere. It is of interest whether individual features have one-to-one correspondence in terms of helicity at different atmospheric heights. We use UBF \\Halpha images from the Dunn Solar Telescope (DST) and other \\Halpha data from Udaipur Solar Observatory and Big Bear Solar Observatory. Near-simultaneous vector magnetograms from the DST are used to establish one-to-one correspondence of helicity at photospheric and chromospheric heights. We plan to extend this investigation with more data including coronal intensities.

  19. Synthesis and structure of neutral double helicate

    Institute of Scientific and Technical Information of China (English)

    SU, Xun-Cheng; ZHOU, Zhi-Fen; ZHU, Shou-Rong; CHEN, Yun-Ti; LENG, Xue-Bing; WENG, Lin-Hong; LIN, Hua-Kuan

    2000-01-01

    A new approach to geaerating supramolecular architectures, based on easy-to-prepare sehiff base ligands, is described to gether with its application to the self-assembly of supramolecu lar neutral double helicates.

  20. Mechanical resonances of helically coiled carbon nanowires

    National Research Council Canada - National Science Library

    Saini, D; Behlow, H; Podila, R; Dickel, D; Pillai, B; Skove, M J; Serkiz, S M; Rao, A M

    2014-01-01

    ...) mainly due to their geometrical complexity. The advent of helically coiled micro/nanoscale structures in nano-robotics, nano-inductors, and impact protection coatings has necessitated the development of new methodologies for determining...

  1. Microfluidic Lithography of Bioinspired Helical Micromotors.

    Science.gov (United States)

    Yu, Yunru; Shang, Luoran; Gao, Wei; Zhao, Ze; Wang, Huan; Zhao, Yuanjin

    2017-07-29

    Considerable efforts have been devoted to developing artificial micro/nanomotors that can convert energy into movement. A flow lithography integrated microfluidic spinning and spiraling system is developed for the continuous generation of bioinspired helical micromotors. Because the generation processes could be precisely tuned by adjusting the flow rates and the illuminating frequency, the length, diameter, and pitch of the helical micromotors were highly controllable. Benefiting from the fast online gelation and polymerization, the resultant helical micromotors could be imparted with Janus, triplex, and core-shell cross-sectional structures that have never been achieved by other methods. Owing to the spatially controlled encapsulation of functional nanoparticles in the microstructures, the helical micromotors can perform locomotion not only by magnetically actuated rotation or corkscrew motion but also through chemically powered catalytic reaction. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Helical magnetized wiggler for synchrotron radiation laser

    CERN Document Server

    Wang Mei; Hirshfield, J L

    1999-01-01

    A helical magnetized iron wiggler has been built for a novel infrared synchrotron radiation laser (SRL) experiment. The wiggler consists of four periods of helical iron structure immersed in a solenoid field. This wiggler is to impart transverse velocity to a prebunched 6 MeV electron beam, and thus to obtain a desired high orbit pitch ratio for the SRL. Field tapering at beam entrance is considered and tested on a similar wiggler. Analytic and simulated characteristics of wigglers of this type are discussed and the performance of the fabricated wigglers is demonstrated experimentally. A 4.7 kG peak field was measured for a 6.4 mm air gap and a 5.4 cm wiggler period at a 20 kG solenoid field. The measured helical fields compare favorably with the analytical solution. This type of helical iron wigglers has the potential to be scaled to small periods with strong field amplitude.

  3. STUDY ON A NOVEL ELLIPSOIDAL HELICAL ANTENNA

    Institute of Scientific and Technical Information of China (English)

    Xia Dongyu; Zhang Hou; Wang Chong; Zhang Qianyue

    2007-01-01

    A novel ellipsoidal helical antenna is proposed and studied in this letter.As a special instance,the hemispherical helical antennas are analyzed firstly,which indicates that the characteristics of a two-arm unit are better than that of a single-arm unit.Based on this,the ellipsoidal helical antenna,formed by changing the axial direction's dimension of the two-arm hemispherical helical antenna,is analyzed by the moment method with curved basic and testing function.The effects to VSWR (Voltage Standing Wave Ratio),gain,polarization and patterns by the axial direction's dimensions are investigated.The study results provide dependable gist to the choice of antenna format according to the practical requirements.

  4. Dispersion properties of helical waves in radially inhomogeneous elastic media.

    Science.gov (United States)

    Syresin, D E; Zharnikov, T V; Tyutekin, V V

    2012-06-01

    In this paper, a method describing dispersion curve calculation for waves propagating in radially layered, inhomogeneous isotropic elastic waveguides is developed. Particular emphasis is placed on the helical waves with noninteger azimuthal wavenumbers, which can be potentially applied in such fields as nondestructive evaluation, acoustic tomography, etc., stipulating their practical importance. To solve the problem under consideration, the matrix Riccati equation is formulated for an impedance matrix. The use of the latter yields a simple form of the dispersion equation. Numerical computation of dispersion curves can encounter difficulties, which are due to potential singularities of the impedance matrix and the necessity to separate roots of the dispersion equation. These difficulties are overcome by employing the Cayley transform and invoking the parametric continuation method. The method developed by the authors is demonstrated by calculating dispersion diagrams in support of helical waves for several models of practical interest. Such computations for an inhomogeneous layer and its approximation by a set of homogeneous layers using a transfer matrix and Riccati equation methods revealed higher computational accuracy of the latter. Dispersion curves calculated for layers with different types of inhomogeneity demonstrated significant discrepancies at low frequencies.

  5. Kinematic dynamo induced by helical waves

    OpenAIRE

    Wei, Xing

    2014-01-01

    We investigate numerically the kinematic dynamo induced by the superposition of two helical waves in a periodic box as a simplified model to understand the dynamo action in astronomical bodies. The effects of magnetic Reynolds number, wavenumber and wave frequency on the dynamo action are studied. It is found that this helical-wave dynamo is a slow dynamo. There exists an optimal wavenumber for the dynamo growth rate. A lower wave frequency facilitates the dynamo action and the oscillations o...

  6. Cosmological Magnetic Fields from Primordial Helical Seeds

    CERN Document Server

    Sigl, G

    2002-01-01

    Most early Universe scenarios predict negligible magnetic fields on cosmological scales if they are unprocessed during subsequent expansion of the Universe. We present a new numerical treatment of the evolution of primordial fields and apply it to weakly helical seeds as they occur in certain early Universe scenarios. We find that initial helicities not much larger than the baryon to photon number can lead to fields of about 10^{-13} Gauss with coherence scales slightly below a kilo-parsec today.

  7. Duality and helicity: A symplectic viewpoint

    Science.gov (United States)

    Elbistan, M.; Duval, C.; Horváthy, P. A.; Zhang, P.-M.

    2016-10-01

    The theorem which says that helicity is the conserved quantity associated with the duality symmetry of the vacuum Maxwell equations is proved by viewing electromagnetism as an infinite dimensional symplectic system. In fact, it is shown that helicity is the moment map of duality acting as an SO (2) group of canonical transformations on the symplectic space of all solutions of the vacuum Maxwell equations.

  8. Orientation determination of protein helical secondary structures using linear and nonlinear vibrational spectroscopy.

    Science.gov (United States)

    Nguyen, Khoi Tan; Le Clair, Stéphanie V; Ye, Shuji; Chen, Zhan

    2009-09-10

    In this paper, we systematically presented the orientation determination of protein helical secondary structures using vibrational spectroscopic methods, particularly, nonlinear sum frequency generation (SFG) vibrational spectroscopy, along with linear vibrational spectroscopic techniques such as infrared spectroscopy and Raman scattering. SFG amide I signals can be collected using different polarization combinations of the input laser beams and output signal beam to measure the second-order nonlinear optical susceptibility components of the helical amide I modes, which are related to their molecular hyperpolarizability elements through the orientation distribution of these helices. The molecular hyperpolarizability elements of amide I modes of a helix can be calculated based on the infrared transition dipole moment and Raman polarizability tensor of the helix; these quantities are determined by using the bond additivity model to sum over the individual infrared transition dipole moments and Raman polarizability tensors, respectively, of the peptide units (or the amino acid residues). The computed overall infrared transition dipole moment and Raman polarizability tensor of a helix can be validated by experimental data using polarized infrared and polarized Raman spectroscopy on samples with well-aligned helical structures. From the deduced SFG hyperpolarizability elements and measured SFG second-order nonlinear susceptibility components, orientation information regarding helical structures can be determined. Even though such orientation information can also be measured using polarized infrared or polarized Raman amide I signals, SFG has a much lower detection limit, which can be used to study the orientation of a helix when its surface coverage is much lower than a monolayer. In addition, the combination of different vibrational spectroscopic techniques, for example, SFG and attenuated total reflectance Fourier transform infrared spectroscopy, provides more

  9. Intrahepatic arterioportal shunt: helical CT findings

    Energy Technology Data Exchange (ETDEWEB)

    Quiroga, S.; Sebastia, M.C.; Moreiras, M.; Pallisa, E.; Rius, J.M.; Alvarez-Castells, A. [I. D. I. Hospital General i Universitari Vall d`Hebron, Barcelona (Spain). Servei de Radiodiagnostic

    1999-08-01

    The purpose of this study was to characterize the appearance of intrahepatic arterioportal shunts (APS) on two-phase helical CT, with emphasis on the importance of the hepatic arterial-dominant phase (HAP) to demonstrate perfusion disorders. We review eight cases of APS diagnosed by helical CT in our institution from January 1996 to March 1997 and describe the CT findings that established diagnosis. Five of them were confirmed by angiography. In seven (87.5 %) cases of APS we found early enhancement of the peripheral portal branches during the HAP of helical CT, whereas the superior mesenteric and splenic veins remained unenhanced. In five (62.5 %) cases of APS, transient, peripheral, triangular parenchymal enhancement was depicted during the HAP of helical CT; in four of these cases there was associated early enhancement of the portal branches. Helical CT can show perfusion alterations that might remain undiagnosed with conventional CT. An understanding of the hemodynamic changes that occur in APS can help in the interpretation of focal transient hepatic parenchymal enhancement and to differentiate APS from hypervascular tumors. We believe that the helical CT findings described herein are characteristic enough to suggest the diagnosis of APS. (orig.) With 3 figs., 1 tab., 16 refs.

  10. The AGS with four helical magnets

    Energy Technology Data Exchange (ETDEWEB)

    Tsoupas, N.; Huang, H.; MacKay, W.W.; Roser, T.; Trbojevic, D.

    2010-02-25

    The idea of using multiple partial helical magnets was applied successfully to the AGS synchrotron, to preserve the proton beam polarization. In this paper we explore in details the idea of using four helical magnets placed symmetrically in the AGS ring. This modification provides many advantages over the present setup of the AGS that uses two partial helical magnets. First, it provides a larger 'spin tune gap' for the placement of the vertical betatron tune of the AGS during acceleration, second, the vertical spin direction during the beam injection and extraction is closer to vertical, third, the symmetric placement of the snakes allows for a better control of the AGS optics, and for reduced values of the beta and eta functions, especially near injection, fourth, the optical properties of the helical magnets also favor the placement of the horizontal betatron tune in the 'spin tune gap', thus eliminating the horizontal spin resonances. In this paper we provide results on the spin tune and on the optics of the AGS with four partial helical magnets, and we compare these results with the present setup of the AGS that uses two partial helical magnets.

  11. Imaging of cochlear implant electrode array with flat-detector CT and conventional multislice CT: comparison of image quality and radiation dose.

    Science.gov (United States)

    Struffert, Tobias; Hertel, Victoria; Kyriakou, Yannis; Krause, Jens; Engelhorn, Tobias; Schick, Bernhard; Iro, Heinrich; Hornung, Joachim; Doerfler, Arnd

    2010-04-01

    Cochlear implantation assessment is possible using commercially available standard flat-detector computed tomography (FD-CT) protocols. Image quality is superior to multislice CT (MSCT). The radiation dose of FD-CT is lower in comparison with MSCT standard protocols and may therefore overcome the limitations of MSCT in the evaluation of cochlear implants. FD-CT offers higher spatial resolution than MSCT. Our objective was to compare the image quality of FD-CT to conventional MSCT in the visualization of a cochlear implant electrode array with respect to radiation exposure. An isolated temporal bone specimen was scanned using a commercially available FD-CT system and a 4 and 64 row MSCT scanner. Different scanning protocols were used. Image quality was assessed by four independent readers using a scoring system with different criteria describing delineation of the cochlea and the electrode array, image noise and spatial resolution. Radiation dose was measured using the CT dose index (CTDI) and a 16 cm acrylic phantom. Image quality was rated superior for FD-CT for all criteria by all readers. Single electrode contacts were only visible in FD-CT and assessment of implant position was improved by FD-CT. The radiation dose of FD-CT was half that of MSCT standard protocols.

  12. A study of the dose modulation systems in two multislice CT scanners; Estudio de los sistemas de modulacion de dosis en dos equipos de tomografia computarizada multicorte

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez Giron, I.; Valverde Moran, J.; Mendez Fernandez, R.; Aramburu Nunez, D.; Nunez Villavicencio, C.; Calzado Cantera, A.

    2009-07-01

    Multislice computed tomography (TCMC) is a technique that for its gradual introduction and the spectacular increase in its indications in clinical practice represents the main contribution to the collective dose in diagnostic radiology. It is essential to optimize the protocols maintaining doses as low as possible without affecting the diagnostic quality of images. Automatic tube current modulation systems are a tool currently available in all CT scanners. They adapt the tube current to morphological characteristics of the patient and the anatomical area under study. The aim of this work has been to analyze two scanners from the same manufacturer and featuring similar geometry by assessing the relative dose differences and image quality. Modulation systems of general use can decrease the dose in a 20-60% with a reduction in the signal to noise ratio between 6% and 37%. Dedicated cardiac-CT modulation system gave rise to high relative differences (36-40%) even when varying the heart rate. Significant changes in image quality were not appreciated though the motion of the heart has not been simulated in this study. (Author) 14 refs.

  13. Long-term follow-up of surgically excluded popliteal artery aneurysms with multi-slice CT angiography and Doppler ultrasound

    Energy Technology Data Exchange (ETDEWEB)

    Deglise, Sebastien; Haller, Claude; Corpataux, Jean-Marc [CHUV, Department of Thoracic and Vascular Surgery, Lausanne (Switzerland); Qanadli, Salah D.; Rizzo, Elena; Doenz, Francesco; Denys, Alban [University Hospital CHUV-University of Lausanne, Department of Radiology, Lausanne (Switzerland); Ducrey, Nicolas [CHUV, Department of Angiology, Lausanne (Switzerland)

    2006-06-15

    The purpose of this study was to evaluate the role of multi-slice computed tomography (MSCT) angiography in the follow-up of popliteal artery aneurysms (PAAs) that have been operated on. Aneurysm exclusion and progression, graft patency and graft-related complications were analyzed. Fourteen patients with 21 surgically excluded PAAs were evaluated with MSCT angiography with slice thickness of 1.25 mm. The mean follow-up time was 67 months. MSCT demonstrated blood flow in six non-excluded PAAs (24%), with an average increase in the diameter of 21 mm over time. Fifteen PAAs demonstrated no blood flow and revealed an average decrease of 7 mm in diameter. The origin of this residual perfusion was demonstrated, and collaterals were involved in five of six non-excluded PAAs. In addition, MSCT demonstrated three graft stenoses. Furthermore, two occluded grafts were visualized. Twenty-four percent of the patients after surgical exclusion of PAAs revealed residual perfusion within the aneurysmal sac during follow-up, with a significant increase in the aneurysmal size with MSCT. Moreover, evaluation of the graft patency could also be done as could demonstration of anastomotic abnormalities. Thus, MSCT might be considered as a new tool to evaluate residual collateral feeding of popliteal aneurysmal sac and could be useful in identification and localization of feeding vessels. (orig.)

  14. Single-handed helical wrapping of single-walled carbon nanotubes by chiral, ionic, semiconducting polymers.

    Science.gov (United States)

    Deria, Pravas; Von Bargen, Christopher D; Olivier, Jean-Hubert; Kumbhar, Amar S; Saven, Jeffery G; Therien, Michael J

    2013-10-30

    We establish the requisite design for aryleneethynylene polymers that give rise to single-handed helical wrapping of single-walled carbon nanotubes (SWNTs). Highly charged semiconducting polymers that utilize either an (R)- or (S)-1,1'-bi-2-naphthol component in their respective conjugated backbones manifest HRTEM and AFM images of single-chain-wrapped SWNTs that reveal significant preferences for the anticipated helical wrapping handedness; statistical analysis of these images, however, indicates that ∼20% of the helical structures are formed with the "unexpected" handedness. CD spectroscopic data, coupled with TDDFT-based computational studies that correlate the spectral signatures of semiconducting polymer-wrapped SWNT assemblies with the structural properties of the chiral 1,1'-binaphthyl unit, suggest strongly that two distinct binaphthalene SWNT binding modes, cisoid-facial and cisoid-side, are possible for these polymers, with the latter mode responsible for inversion of helical chirality and the population of polymer-SWNT superstructures that feature the unexpected polymer helical wrapping chirality at the nanotube surface. Analogous aryleneethynylene polymers were synthesized that feature a 2,2'-(1,3-benzyloxy)-bridged (b)-1,1'-bi-2-naphthol unit: this 1,1'-bi-2-naphthol derivative is characterized by a bridging 2,2'-1,3 benzyloxy tether that restricts the torsional angle between the two naphthalene subunits along its C1-C1' chirality axis to larger, oblique angles that facilitate more extensive van der Waals contact of the naphthyl subunits with the nanotube. Similar microscopic, spectroscopic, and computational studies determine that chiral polymers based on conformationally restricted transoid binaphthyl units direct preferential facial binding of the polymer with the SWNT and thereby guarantee helically wrapped polymer-nanotube superstructures of fixed helical chirality. Molecular dynamics simulations provide an integrated picture tying together the

  15. Is correction necessary when clinically determining quantitative cerebral perfusion parameters from multi-slice dynamic susceptibility contrast MR studies?

    Science.gov (United States)

    Salluzzi, M.; Frayne, R.; Smith, M. R.

    2006-01-01

    Several groups have modified the standard singular value decomposition (SVD) algorithm to produce delay-insensitive cerebral blood flow (CBF) estimates from dynamic susceptibility contrast (DSC) perfusion studies. However, new dependences of CBF estimates on bolus arrival times and slice position in multi-slice studies have been recently recognized. These conflicting findings can be reconciled by accounting for several experimental and algorithmic factors. Using simulation and clinical studies, the non-simultaneous measurement of arterial and tissue concentration curves (relative slice position) in a multi-slice study is shown to affect time-related perfusion parameters, e.g. arterial-tissue-delay measurements. However, the current clinical impact of relative slice position on amplitude-related perfusion parameters, e.g. CBF, can be expected to be small unless any of the following conditions are present individually or in combination: (a) high concentration curve signal-to-noise ratios, (b) small tissue mean transit times, (c) narrow arterial input functions or (d) low temporal resolution of the DSC image sequence. Recent improvements in magnetic resonance (MR) technology can easily be expected to lead to scenarios where these effects become increasingly important sources of inaccuracy for all perfusion parameter estimates. We show that using Fourier interpolated (high temporal resolution) residue functions reduces the systematic error of the perfusion parameters obtained from multi-slice studies. Preliminary results associated with this paper were presented at ISMRM 12th Scientific Meeting and Exhibition, Kyoto, Japan, 2004.

  16. Assessment of the arteriovenous cerebrovascular system by multi-slice CT. A single-bolus, monophasic protocol

    Energy Technology Data Exchange (ETDEWEB)

    Klingebiel, R.; Zimmer, C. [Charite CM, Humboldt Univ., Berlin (Germany). Neuroradiology Section; Rogalla, P.; Kivelitz, D. [Charite CM, Humboldt Univ., Berlin (Germany). Dept. of Radiology; Bohner, G. [Charite CM, Humboldt Univ., Berlin (Germany). Neuroradiology Section; Goetze, R. [Charite CM, Humboldt Univ., Berlin (Germany). Dept. of Radiology; Lehmann, R. [Charite CM, Humboldt Univ., Berlin (Germany). Neuroradiology Section

    2001-11-01

    Purpose: We present a protocol for the non-invasive angiographic assessment of the arterial and venous cerebrovascular (CV) system by multi-slice CT. Material and Methods: Data acquisition was performed in a multi-slice CT scanner with a scan range from the carotid bifurcation to the vertex and manual scan start following i.v. administration of 120 ml iodinated contrast medium with a flow rate of 4 ml/s. This protocol was applied in 12 patients with symptoms of acute CV insufficiency. Results: In all patients, comprehensive imaging of the arteriovenous CV system was achieved including the common carotid bifurcation, the third segment of the major cerebral arteries, the dural sinus and the internal cerebral veins. Various CV pathologies, such as a territorial artery occlusion, a thrombotic obstruction of the internal carotid artery, an intracranial arteriovenous malformation and a sinus vein thrombosis, were successfully evaluated. Conclusion: Comprehensive assessment of the arteriovenous CV system is possible by the use of a single-bolus, monophasic multi-slice scan technique.

  17. Is correction necessary when clinically determining quantitative cerebral perfusion parameters from multi-slice dynamic susceptibility contrast MR studies?

    Science.gov (United States)

    Salluzzi, M; Frayne, R; Smith, M R

    2006-01-21

    Several groups have modified the standard singular value decomposition (SVD) algorithm to produce delay-insensitive cerebral blood flow (CBF) estimates from dynamic susceptibility contrast (DSC) perfusion studies. However, new dependences of CBF estimates on bolus arrival times and slice position in multi-slice studies have been recently recognized. These conflicting findings can be reconciled by accounting for several experimental and algorithmic factors. Using simulation and clinical studies, the non-simultaneous measurement of arterial and tissue concentration curves (relative slice position) in a multi-slice study is shown to affect time-related perfusion parameters, e.g. arterial-tissue-delay measurements. However, the current clinical impact of relative slice position on amplitude-related perfusion parameters, e.g. CBF, can be expected to be small unless any of the following conditions are present individually or in combination: (a) high concentration curve signal-to-noise ratios, (b) small tissue mean transit times, (c) narrow arterial input functions or (d) low temporal resolution of the DSC image sequence. Recent improvements in magnetic resonance (MR) technology can easily be expected to lead to scenarios where these effects become increasingly important sources of inaccuracy for all perfusion parameter estimates. We show that using Fourier interpolated (high temporal resolution) residue functions reduces the systematic error of the perfusion parameters obtained from multi-slice studies.

  18. COMPUTING

    CERN Multimedia

    I. Fisk

    2013-01-01

    Computing activity had ramped down after the completion of the reprocessing of the 2012 data and parked data, but is increasing with new simulation samples for analysis and upgrade studies. Much of the Computing effort is currently involved in activities to improve the computing system in preparation for 2015. Operations Office Since the beginning of 2013, the Computing Operations team successfully re-processed the 2012 data in record time, not only by using opportunistic resources like the San Diego Supercomputer Center which was accessible, to re-process the primary datasets HTMHT and MultiJet in Run2012D much earlier than planned. The Heavy-Ion data-taking period was successfully concluded in February collecting almost 500 T. Figure 3: Number of events per month (data) In LS1, our emphasis is to increase efficiency and flexibility of the infrastructure and operation. Computing Operations is working on separating disk and tape at the Tier-1 sites and the full implementation of the xrootd federation ...

  19. Computer

    CERN Document Server

    Atkinson, Paul

    2011-01-01

    The pixelated rectangle we spend most of our day staring at in silence is not the television as many long feared, but the computer-the ubiquitous portal of work and personal lives. At this point, the computer is almost so common we don't notice it in our view. It's difficult to envision that not that long ago it was a gigantic, room-sized structure only to be accessed by a few inspiring as much awe and respect as fear and mystery. Now that the machine has decreased in size and increased in popular use, the computer has become a prosaic appliance, little-more noted than a toaster. These dramati

  20. Alternative Methods for Field Corrections in Helical Solenoids

    Energy Technology Data Exchange (ETDEWEB)

    Lopes, M. L. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Krave, S. T. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Tompkins, J. C. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Yonehara, K. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Flanagan, G. [Muons Inc., Batavia, IL (United States); Kahn, S. A. [Muons Inc., Batavia, IL (United States); Melconian, K. [Texas A & M Univ., College Station, TX (United States)

    2015-05-01

    Helical cooling channels have been proposed for highly efficient 6D muon cooling. Helical solenoids produce solenoidal, helical dipole, and helical gradient field components. Previous studies explored the geometric tunability limits on these main field components. In this paper we present two alternative correction schemes, tilting the solenoids and the addition of helical lines, to reduce the required strength of the anti-solenoid and add an additional tuning knob.

  1. COMPUTING

    CERN Multimedia

    I. Fisk

    2010-01-01

    Introduction It has been a very active quarter in Computing with interesting progress in all areas. The activity level at the computing facilities, driven by both organised processing from data operations and user analysis, has been steadily increasing. The large-scale production of simulated events that has been progressing throughout the fall is wrapping-up and reprocessing with pile-up will continue. A large reprocessing of all the proton-proton data has just been released and another will follow shortly. The number of analysis jobs by users each day, that was already hitting the computing model expectations at the time of ICHEP, is now 33% higher. We are expecting a busy holiday break to ensure samples are ready in time for the winter conferences. Heavy Ion An activity that is still in progress is computing for the heavy-ion program. The heavy-ion events are collected without zero suppression, so the event size is much large at roughly 11 MB per event of RAW. The central collisions are more complex and...

  2. COMPUTING

    CERN Multimedia

    M. Kasemann P. McBride Edited by M-C. Sawley with contributions from: P. Kreuzer D. Bonacorsi S. Belforte F. Wuerthwein L. Bauerdick K. Lassila-Perini M-C. Sawley

    Introduction More than seventy CMS collaborators attended the Computing and Offline Workshop in San Diego, California, April 20-24th to discuss the state of readiness of software and computing for collisions. Focus and priority were given to preparations for data taking and providing room for ample dialog between groups involved in Commissioning, Data Operations, Analysis and MC Production. Throughout the workshop, aspects of software, operating procedures and issues addressing all parts of the computing model were discussed. Plans for the CMS participation in STEP’09, the combined scale testing for all four experiments due in June 2009, were refined. The article in CMS Times by Frank Wuerthwein gave a good recap of the highly collaborative atmosphere of the workshop. Many thanks to UCSD and to the organizers for taking care of this workshop, which resulted in a long list of action items and was definitely a success. A considerable amount of effort and care is invested in the estimate of the comput...

  3. TC multicorte (TCMC cardiaca: aplicaciones clínicas Multislice CT of the heart: clinical applications

    Directory of Open Access Journals (Sweden)

    G. Bastarrika

    2004-04-01

    Full Text Available La introducción de los equipos de TC multicorte y el desarrollo de técnicas de adquisición de imágenes con sincronización electrocardiográfica y reconstrucción retrospectiva han permitido que la TC multicorte cardiaca se pueda considerar hoy en día una técnica no invasiva muy útil para el estudio de la patología cardiaca en la práctica clínica diaria. La valoración de las arterias coronarias es una de las principales aplicaciones clínicas de esta técnica diagnóstica e incluye la detección y cuantificación del calcio coronario, la coronariografía por TC multicorte (estudio de la anatomía coronaria, variantes anatómicas y anomalías del origen y trayecto, la valoración angiográfica de la permeabilidad de injertos aortocoronarios y endoprótesis vasculares y la caracterización de las placas de ateroma. Los nuevos programas de reconstrucción y postprocesamiento permiten obtener, además, parámetros de morfología y contracción miocárdica y función cardiaca. Otras aplicaciones clínicas incluyen la caracterización de masas cardiacas intracavitarias y la valoración del pericardio.Since the introduction of last generation multislice MSCT systems and the development of simultaneous electrocardiographic-tracing image acquisition and retrospective reconstruction techniques into clinical routine, cardiac MSCT has been considered a very useful non-invasive technique for the study of cardiac pathology in the daily clinical practice. One of the main clinical applications of this diagnostic technique is the evaluation of the coronary arteries including detection and quantification of coronary calcium, multislice CT coronary angiography (anatomy, anatomical variants and anomalies of the origin and course, the angiographic evaluation of the patency of aortocoronary by-pass grafts and coronary stents, and plaque characterization. The new reconstruction and postprocessing programs allow to obtain, in addition, parameters of

  4. Hydrogels of Superlong Helices to Synthesize Hybrid Ag-Helical Nanomaterials.

    Science.gov (United States)

    Li, Guihua; Wang, Yitong; Wang, Ling; Song, Aixin; Hao, Jingcheng

    2016-11-22

    The gelation behavior of mixtures of sodium deoxycholate (NaDC) and glutathione (GSH) in water is investigated. The system exhibits a structural transition of self-assembled hydrogels from nanofibers to nanohelix structures, and then to helical ribbons with increasing GSH concentration. Superlong helical nanofibers with left- and right-handed orientations are produced by tuning the concentration of GSH at a fixed concentration of NaDC. Random coil and β-sheet structures are significant for the formation of the helical structures, and are indicated by circular dichroism (CD) and Fourier transform infrared (FT-IR) spectra. The mechanical strength of the "weak" hydrogels is enhanced by the introduction of appropriate suitable amount of AgNO3. Furthermore, the controlled growth of Ag nanoparticles at spatially arranged locations along the nanohelices (hybrid Ag-helical nanomaterial) is readily achieved by UV reduction of Ag (I) ions on the supramolecular helical templates.

  5. COMPUTING

    CERN Multimedia

    I. Fisk

    2010-01-01

    Introduction The first data taking period of November produced a first scientific paper, and this is a very satisfactory step for Computing. It also gave the invaluable opportunity to learn and debrief from this first, intense period, and make the necessary adaptations. The alarm procedures between different groups (DAQ, Physics, T0 processing, Alignment/calibration, T1 and T2 communications) have been reinforced. A major effort has also been invested into remodeling and optimizing operator tasks in all activities in Computing, in parallel with the recruitment of new Cat A operators. The teams are being completed and by mid year the new tasks will have been assigned. CRB (Computing Resource Board) The Board met twice since last CMS week. In December it reviewed the experience of the November data-taking period and could measure the positive improvements made for the site readiness. It also reviewed the policy under which Tier-2 are associated with Physics Groups. Such associations are decided twice per ye...

  6. COMPUTING

    CERN Multimedia

    P. McBride

    It has been a very active year for the computing project with strong contributions from members of the global community. The project has focused on site preparation and Monte Carlo production. The operations group has begun processing data from P5 as part of the global data commissioning. Improvements in transfer rates and site availability have been seen as computing sites across the globe prepare for large scale production and analysis as part of CSA07. Preparations for the upcoming Computing Software and Analysis Challenge CSA07 are progressing. Ian Fisk and Neil Geddes have been appointed as coordinators for the challenge. CSA07 will include production tests of the Tier-0 production system, reprocessing at the Tier-1 sites and Monte Carlo production at the Tier-2 sites. At the same time there will be a large analysis exercise at the Tier-2 centres. Pre-production simulation of the Monte Carlo events for the challenge is beginning. Scale tests of the Tier-0 will begin in mid-July and the challenge it...

  7. COMPUTING

    CERN Multimedia

    M. Kasemann

    Introduction During the past six months, Computing participated in the STEP09 exercise, had a major involvement in the October exercise and has been working with CMS sites on improving open issues relevant for data taking. At the same time operations for MC production, real data reconstruction and re-reconstructions and data transfers at large scales were performed. STEP09 was successfully conducted in June as a joint exercise with ATLAS and the other experiments. It gave good indication about the readiness of the WLCG infrastructure with the two major LHC experiments stressing the reading, writing and processing of physics data. The October Exercise, in contrast, was conducted as an all-CMS exercise, where Physics, Computing and Offline worked on a common plan to exercise all steps to efficiently access and analyze data. As one of the major results, the CMS Tier-2s demonstrated to be fully capable for performing data analysis. In recent weeks, efforts were devoted to CMS Computing readiness. All th...

  8. COMPUTING

    CERN Multimedia

    M. Kasemann

    CCRC’08 challenges and CSA08 During the February campaign of the Common Computing readiness challenges (CCRC’08), the CMS computing team had achieved very good results. The link between the detector site and the Tier0 was tested by gradually increasing the number of parallel transfer streams well beyond the target. Tests covered the global robustness at the Tier0, processing a massive number of very large files and with a high writing speed to tapes.  Other tests covered the links between the different Tiers of the distributed infrastructure and the pre-staging and reprocessing capacity of the Tier1’s: response time, data transfer rate and success rate for Tape to Buffer staging of files kept exclusively on Tape were measured. In all cases, coordination with the sites was efficient and no serious problem was found. These successful preparations prepared the ground for the second phase of the CCRC’08 campaign, in May. The Computing Software and Analysis challen...

  9. COMPUTING

    CERN Multimedia

    I. Fisk

    2011-01-01

    Introduction It has been a very active quarter in Computing with interesting progress in all areas. The activity level at the computing facilities, driven by both organised processing from data operations and user analysis, has been steadily increasing. The large-scale production of simulated events that has been progressing throughout the fall is wrapping-up and reprocessing with pile-up will continue. A large reprocessing of all the proton-proton data has just been released and another will follow shortly. The number of analysis jobs by users each day, that was already hitting the computing model expectations at the time of ICHEP, is now 33% higher. We are expecting a busy holiday break to ensure samples are ready in time for the winter conferences. Heavy Ion The Tier 0 infrastructure was able to repack and promptly reconstruct heavy-ion collision data. Two copies were made of the data at CERN using a large CASTOR disk pool, and the core physics sample was replicated ...

  10. COMPUTING

    CERN Multimedia

    I. Fisk

    2012-01-01

    Introduction Computing continued with a high level of activity over the winter in preparation for conferences and the start of the 2012 run. 2012 brings new challenges with a new energy, more complex events, and the need to make the best use of the available time before the Long Shutdown. We expect to be resource constrained on all tiers of the computing system in 2012 and are working to ensure the high-priority goals of CMS are not impacted. Heavy ions After a successful 2011 heavy-ion run, the programme is moving to analysis. During the run, the CAF resources were well used for prompt analysis. Since then in 2012 on average 200 job slots have been used continuously at Vanderbilt for analysis workflows. Operations Office As of 2012, the Computing Project emphasis has moved from commissioning to operation of the various systems. This is reflected in the new organisation structure where the Facilities and Data Operations tasks have been merged into a common Operations Office, which now covers everything ...

  11. COMPUTING

    CERN Multimedia

    M. Kasemann

    Introduction More than seventy CMS collaborators attended the Computing and Offline Workshop in San Diego, California, April 20-24th to discuss the state of readiness of software and computing for collisions. Focus and priority were given to preparations for data taking and providing room for ample dialog between groups involved in Commissioning, Data Operations, Analysis and MC Production. Throughout the workshop, aspects of software, operating procedures and issues addressing all parts of the computing model were discussed. Plans for the CMS participation in STEP’09, the combined scale testing for all four experiments due in June 2009, were refined. The article in CMS Times by Frank Wuerthwein gave a good recap of the highly collaborative atmosphere of the workshop. Many thanks to UCSD and to the organizers for taking care of this workshop, which resulted in a long list of action items and was definitely a success. A considerable amount of effort and care is invested in the estimate of the co...

  12. Spur, helical, and spiral bevel transmission life modeling

    Science.gov (United States)

    Savage, Michael; Rubadeux, Kelly L.; Coe, Harold H.; Coy, John J.

    1994-04-01

    A computer program, TLIFE, which estimates the life, dynamic capacity, and reliability of aircraft transmissions, is presented. The program enables comparisons of transmission service life at the design stage for optimization. A variety of transmissions may be analyzed including: spur, helical, and spiral bevel reductions as well as series combinations of these reductions. The basic spur and helical reductions include: single mesh, compound, and parallel path plus revert star and planetary gear trains. A variety of straddle and overhung bearing configurations on the gear shafts are possible as is the use of a ring gear for the output. The spiral bevel reductions include single and dual input drives with arbitrary shaft angles. The program is written in FORTRAN 77 and has been executed both in the personal computer DOS environment and on UNIX workstations. The analysis may be performed in either the SI metric or the English inch system of units. The reliability and life analysis is based on the two-parameter Weibull distribution lives of the component gears and bearings. The program output file describes the overall transmission and each constituent transmission, its components, and their locations, capacities, and loads. Primary output is the dynamic capacity and 90-percent reliability and mean lives of the unit transmissions and the overall system which can be used to estimate service overhaul frequency requirements. Two examples are presented to illustrate the information available for single element and series transmissions.

  13. Assessment of left atrial volume and function: a comparative study between echocardiography, magnetic resonance imaging and multi slice computed tomography

    DEFF Research Database (Denmark)

    Kühl, J Tobias; Lønborg, Jacob; Fuchs, Andreas

    2012-01-01

    dynamic LA volume changes. Conversely, cardiac magnetic resonance imaging (CMR) and multi-slice computed tomography (MSCT) appears more appropriate for such measures. We sought to determine the relationship between LA size assessed with TTE and LA size and function assessed with CMR and MSCT. Fifty...

  14. Human Skin as Arrays of Helical Antennas in the Millimeter and Submillimeter Wave Range

    Science.gov (United States)

    Feldman, Yuri; Puzenko, Alexander; Ben Ishai, Paul; Caduff, Andreas; Agranat, Aharon J.

    2008-03-01

    Recent studies of the minute morphology of the skin by optical coherence tomography showed that the sweat ducts in human skin are helically shaped tubes, filled with a conductive aqueous solution. A computer simulation study of these structures in millimeter and submillimeter wave bands show that the human skin functions as an array of low-Q helical antennas. Experimental evidence is presented that the spectral response in the sub-Terahertz region is governed by the level of activity of the perspiration system. It is also correlated to physiological stress as manifested by the pulse rate and the systolic blood pressure.

  15. Dark matter candidates, helicity effects and new affine gravity with torsion

    Science.gov (United States)

    Alvarez-Castillo, David; Cirilo-Lombardo, Diego Julio; Zamora-Saa, Jilberto

    2017-03-01

    The cross section for neutrino helicity spin-flip obtained from a new f (R , T) model of gravitation with dynamic torsion field is phenomenologically analyzed. To this end, due to the logarithmical energy dependence of the cross section, the relation with the axion decay constant fa (Peccei-Quinn parameter) is used. Consequently the link with the phenomenological energy/mass window is found from the astrophysical and high energy viewpoints. The highest helicity spin-flip cross-sectional values presented in this work coincide with a recent estimation on the axion mass computed in the framework of finite temperature extended lattice QCD and under cosmological considerations.

  16. Fabrication and experimentation of FRP helical spring

    Science.gov (United States)

    Ekanthappa, J.; Shiva Shankar, G. S.; Amith, B. M.; Gagan, M.

    2016-09-01

    In present scenario, the automobile industry sector is showing increased interest in reducing the unsprung weight of the automobile & hence increasing the fuel Efficiency. One of the feasible sub systems of a vehicle where weight reduction may be attempted is vehicle- suspension system. Usage of composite material is a proven way to lower the component weight without any compromise in strength. The composite materials are having high specific strength, more elastic strain energy storage capacity in comparison with those of steel. Therefore, helical coil spring made of steel is replaceable by composite cylindrical helical coil spring. This research aims at preparing a re-usable mandrel (mould) of Mild steel, developing a setup for fabrication, fabrication of FRP helical spring using continuous glass fibers and Epoxy Resin (Polymer). Experimentation has been conducted on fabricated FRP helical spring to determine its strength parameters & for failure analysis. It is found that spring stiffness (K) of Glass/Epoxy helical-spring is greater than steel-coil spring with reduced weight.

  17. Functional Study of the Heart using MRI and Multi-slice CT (MSCT

    Directory of Open Access Journals (Sweden)

    "Sh. Akhlaghpour

    2005-08-01

    Full Text Available Introduction & Background: By using newer imaging techniques (MRI and MSCT, it is possible to perform functional studies of the heart including, wall mo-tion, chamber volume evaluation, and myocardial mass and wall thickness. While MRI had recently been introduced as the gold standard method for the morphological and functional studies of the heart, recent advances in the number of detectors, rotation time, and reconstruction protocols made Multislice CT (MSCT another new application for functional studies of the heart too. Ordinary raw data for coro-nary CT angiography is sufficient for these functional studies. Apart from the point that which technique is to be used to get a standard and reproducible meas-urement, a proper imaging strategy is necessary. To use MSCT, various softwares are available for these studies. By the use of these two modalities, valvular evaluations are also possible as addressed in many recent publications. In this article the strategy for functional study of the heart is presented and some case studies are also discussed.

  18. Multislice CT angiography in aortic stent grafting: Relationship between image noise and body mass index

    Energy Technology Data Exchange (ETDEWEB)

    Sun Zhonghua [Discipline of Medical Imaging, Department of Imaging and Applied Physics, Curtin University of Technology, GPO Box U1987, Perth, Western Australia 6845 (Australia)]. E-mail: z.sun@curtin.edu.au

    2007-03-15

    Purpose: To investigate the correlation between image noise and body mass index (BMI) in multislice CT angiography (MSCT) for patients with abdominal aortic aneurysm (AAA) treated with endovascular stent grafts. Materials and methods: Seventeen patients who underwent MSCT following endovascular repair of AAA were included in the study. Image noise (standard deviation of the CT attenuation: S.D.) and signal to noise ratio (SNR) were plotted against BMI to demonstrate the correlation using a linear regression method. Image quality of 3D reconstructions was correlated to the SNR and BMI. Results: The r-value of linear regression between S.D. and BMI was 0.578 (p < 0.05), 0.835 and 0.802 (p < 0.001), respectively, at the level of renal artery, aortic aneurysm and common iliac artery. The r-value of linear regression between SNR and BMI was 0.332, 0.516 and 0.552 (p < 0.05), respectively, at above three levels. Image quality of 3D reconstructions was compromised in five patients and diagnosis was affected in two patients with BMI more than 30. Conclusion: A significant correlation was observed between image noise and BMI in MSCT angiography of endovascular repair of AAA. Our findings are valuable for optimisation of MSCT angiography scanning protocols and reduction of radiation dose in MSCT examinations.

  19. Whole left ventricular functional assessment from two minutes free breathing multi-slice CINE acquisition

    Science.gov (United States)

    Usman, M.; Atkinson, D.; Heathfield, E.; Greil, G.; Schaeffter, T.; Prieto, C.

    2015-04-01

    Two major challenges in cardiovascular MRI are long scan times due to slow MR acquisition and motion artefacts due to respiratory motion. Recently, a Motion Corrected-Compressed Sensing (MC-CS) technique has been proposed for free breathing 2D dynamic cardiac MRI that addresses these challenges by simultaneously accelerating MR acquisition and correcting for any arbitrary motion in a compressed sensing reconstruction. In this work, the MC-CS framework is combined with parallel imaging for further acceleration, and is termed Motion Corrected Sparse SENSE (MC-SS). Validation of the MC-SS framework is demonstrated in eight volunteers and three patients for left ventricular functional assessment and results are compared with the breath-hold acquisitions as reference. A non-significant difference (P > 0.05) was observed in the volumetric functional measurements (end diastolic volume, end systolic volume, ejection fraction) and myocardial border sharpness values obtained with the proposed and gold standard methods. The proposed method achieves whole heart multi-slice coverage in 2 min under free breathing acquisition eliminating the time needed between breath-holds for instructions and recovery. This results in two-fold speed up of the total acquisition time in comparison to the breath-hold acquisition.

  20. Multi-slice myelin water imaging for practical clinical applications at 3.0 T.

    Science.gov (United States)

    Guo, Junyu; Ji, Qing; Reddick, Wilburn E

    2013-09-01

    Myelin water imaging is a promising, noninvasive technique for evaluating white matter diseases such as multiple sclerosis and other leukoencephalopathies (LE), and monitoring myelination in early childhood. Unfortunately, poor image quality and a long acquisition time are major obstacles to practical clinical applications. In this study, a novel postprocessing method with an efficient multi-slice acquisition scheme, called T2 spectrum analysis using a weighted regularized non-negative least squares algorithm and nonlocal mean filter (T2SPARC), is presented to overcome these obstacles and achieve a shorter acquisition time, higher image quality, and large volume coverage. In vivo results from healthy volunteers and a patient with LE showed that the T2SPARC method can generate robust and high-quality myelin water fraction maps of 10 slices within 11 min. This method also yields some useful byproducts such as intra- and extracellular water fraction and long T2 tissue water fraction maps, which can quantify lesions in different brain diseases.

  1. Multislice simulations for in-situ HRTEM studies of nanostructured magnesium hydride at ambient hydrogen pressure.

    Science.gov (United States)

    Surrey, Alexander; Schultz, Ludwig; Rellinghaus, Bernd

    2017-01-31

    The use of transmission electron microscopy (TEM) for the structural characterization of many nanostructured hydrides, which are relevant for solid state hydrogen storage, is hindered due to a rapid decomposition of the specimen upon irradiation with the electron beam. Environmental TEM allows to stabilize the hydrides by applying a hydrogen back pressure of up to 4.5 bar in a windowed environmental cell. The feasibility of high-resolution TEM (HRTEM) investigations of light weight metals and metal hydrides in such a "nanoreactor" is studied theoretically by means of multislice HRTEM contrast simulations using Mg and its hydride phase, MgH2, as model system. Such a setup provides the general opportunity to study dehydrogenation and hydrogenation reactions at the nanoscale under technological application conditions. We analyze the dependence of both the spatial resolution and the HRTEM image contrast on parameters such as the defocus, the metal/hydride thickness, and the hydrogen pressure in order to explore the possibilities and limitations of in-situ experiments with windowed environmental cells. Such simulations may be highly valuable to pre-evaluate future experimental studies.

  2. Closed surface modeling with helical line measurement data

    Institute of Scientific and Technical Information of China (English)

    LI Ruqiong; LI Guanghu; WANG Yuhan

    2007-01-01

    Models for surface modeling of free-form surface and massive data points are becoming an important feature in commercial computer aided design/computer-aided manu- facturing software. However, there are many problems to be solved in this area, especially for closed free-form surface modeling. This article presents an effective method for cloud data closed surface modeling from asynchronous profile modeling measurement. It includes three steps: first, the cloud data are preprocessed for smoothing; second, a helical line is segmented to form triangle meshes; and third, Bezier surface patches are created over a triangle mesh and trimmed to shape on an entire surface. In the end, an illustrative example of shoe last surface modeling is given to show the availability of this method.

  3. COMPUTING

    CERN Multimedia

    Matthias Kasemann

    Overview The main focus during the summer was to handle data coming from the detector and to perform Monte Carlo production. The lessons learned during the CCRC and CSA08 challenges in May were addressed by dedicated PADA campaigns lead by the Integration team. Big improvements were achieved in the stability and reliability of the CMS Tier1 and Tier2 centres by regular and systematic follow-up of faults and errors with the help of the Savannah bug tracking system. In preparation for data taking the roles of a Computing Run Coordinator and regular computing shifts monitoring the services and infrastructure as well as interfacing to the data operations tasks are being defined. The shift plan until the end of 2008 is being put together. User support worked on documentation and organized several training sessions. The ECoM task force delivered the report on “Use Cases for Start-up of pp Data-Taking” with recommendations and a set of tests to be performed for trigger rates much higher than the ...

  4. COMPUTING

    CERN Multimedia

    M. Kasemann

    Introduction A large fraction of the effort was focused during the last period into the preparation and monitoring of the February tests of Common VO Computing Readiness Challenge 08. CCRC08 is being run by the WLCG collaboration in two phases, between the centres and all experiments. The February test is dedicated to functionality tests, while the May challenge will consist of running at all centres and with full workflows. For this first period, a number of functionality checks of the computing power, data repositories and archives as well as network links are planned. This will help assess the reliability of the systems under a variety of loads, and identifying possible bottlenecks. Many tests are scheduled together with other VOs, allowing the full scale stress test. The data rates (writing, accessing and transfer¬ring) are being checked under a variety of loads and operating conditions, as well as the reliability and transfer rates of the links between Tier-0 and Tier-1s. In addition, the capa...

  5. COMPUTING

    CERN Multimedia

    P. MacBride

    The Computing Software and Analysis Challenge CSA07 has been the main focus of the Computing Project for the past few months. Activities began over the summer with the preparation of the Monte Carlo data sets for the challenge and tests of the new production system at the Tier-0 at CERN. The pre-challenge Monte Carlo production was done in several steps: physics generation, detector simulation, digitization, conversion to RAW format and the samples were run through the High Level Trigger (HLT). The data was then merged into three "Soups": Chowder (ALPGEN), Stew (Filtered Pythia) and Gumbo (Pythia). The challenge officially started when the first Chowder events were reconstructed on the Tier-0 on October 3rd. The data operations teams were very busy during the the challenge period. The MC production teams continued with signal production and processing while the Tier-0 and Tier-1 teams worked on splitting the Soups into Primary Data Sets (PDS), reconstruction and skimming. The storage sys...

  6. COMPUTING

    CERN Multimedia

    Contributions from I. Fisk

    2012-01-01

    Introduction The start of the 2012 run has been busy for Computing. We have reconstructed, archived, and served a larger sample of new data than in 2011, and we are in the process of producing an even larger new sample of simulations at 8 TeV. The running conditions and system performance are largely what was anticipated in the plan, thanks to the hard work and preparation of many people. Heavy ions Heavy Ions has been actively analysing data and preparing for conferences.  Operations Office Figure 6: Transfers from all sites in the last 90 days For ICHEP and the Upgrade efforts, we needed to produce and process record amounts of MC samples while supporting the very successful data-taking. This was a large burden, especially on the team members. Nevertheless the last three months were very successful and the total output was phenomenal, thanks to our dedicated site admins who keep the sites operational and the computing project members who spend countless hours nursing the...

  7. COMPUTING

    CERN Multimedia

    I. Fisk

    2012-01-01

      Introduction Computing activity has been running at a sustained, high rate as we collect data at high luminosity, process simulation, and begin to process the parked data. The system is functional, though a number of improvements are planned during LS1. Many of the changes will impact users, we hope only in positive ways. We are trying to improve the distributed analysis tools as well as the ability to access more data samples more transparently.  Operations Office Figure 2: Number of events per month, for 2012 Since the June CMS Week, Computing Operations teams successfully completed data re-reconstruction passes and finished the CMSSW_53X MC campaign with over three billion events available in AOD format. Recorded data was successfully processed in parallel, exceeding 1.2 billion raw physics events per month for the first time in October 2012 due to the increase in data-parking rate. In parallel, large efforts were dedicated to WMAgent development and integrati...

  8. COMPUTING

    CERN Document Server

    2010-01-01

    Introduction Just two months after the “LHC First Physics” event of 30th March, the analysis of the O(200) million 7 TeV collision events in CMS accumulated during the first 60 days is well under way. The consistency of the CMS computing model has been confirmed during these first weeks of data taking. This model is based on a hierarchy of use-cases deployed between the different tiers and, in particular, the distribution of RECO data to T1s, who then serve data on request to T2s, along a topology known as “fat tree”. Indeed, during this period this model was further extended by almost full “mesh” commissioning, meaning that RECO data were shipped to T2s whenever possible, enabling additional physics analyses compared with the “fat tree” model. Computing activities at the CMS Analysis Facility (CAF) have been marked by a good time response for a load almost evenly shared between ALCA (Alignment and Calibration tasks - highest p...

  9. COMPUTING

    CERN Multimedia

    I. Fisk

    2013-01-01

    Computing operation has been lower as the Run 1 samples are completing and smaller samples for upgrades and preparations are ramping up. Much of the computing activity is focusing on preparations for Run 2 and improvements in data access and flexibility of using resources. Operations Office Data processing was slow in the second half of 2013 with only the legacy re-reconstruction pass of 2011 data being processed at the sites.   Figure 1: MC production and processing was more in demand with a peak of over 750 Million GEN-SIM events in a single month.   Figure 2: The transfer system worked reliably and efficiently and transferred on average close to 520 TB per week with peaks at close to 1.2 PB.   Figure 3: The volume of data moved between CMS sites in the last six months   The tape utilisation was a focus for the operation teams with frequent deletion campaigns from deprecated 7 TeV MC GEN-SIM samples to INVALID datasets, which could be cleaned up...

  10. Unusually Stable Helical Coil Allotrope of Phosphorus.

    Science.gov (United States)

    Liu, Dan; Guan, Jie; Jiang, Jingwei; Tománek, David

    2016-12-14

    We have identified an unusually stable helical coil allotrope of phosphorus. Our ab initio density functional theory calculations indicate that the uncoiled, isolated straight one-dimensional chain is equally stable as a monolayer of black phosphorus dubbed phosphorene. The coiling tendency and the attraction between adjacent coil segments add an extra stabilization energy of ∼12 meV/atom to the coil allotrope, similar in value to the ∼16 meV/atom interlayer attraction in bulk black phosphorus. Thus, the helical coil structure is essentially as stable as black phosphorus, the most stable phosphorus allotrope known to date. With an optimum radius of 2.4 nm, the helical coil of phosphorus may fit well and even form inside wide carbon nanotubes.

  11. FLUID FLOW IN ROTATING HELICAL SQUARE DUCTS

    Institute of Scientific and Technical Information of China (English)

    Chen Hua-jun; Zhang Ben-zhao; Zhang Jin-suo

    2003-01-01

    A numerical study is made for a fully developed laminar flow in rotating helical pipes.Due to the rotation, the Coriolis force can also contribute to the secondary flow.The interaction between rotation, torsion, and curvature complicates the flow characteristics.The effects of rotation and torsion on the flow transitions are studied in details.The results show that there are obvious differences between the flow in rotating ducts and in helical ducts without rotation.Certain hitherto unknown flow patterns are found.The effects of rotation and torsion on the friction factor are also examined.Present results show the characteristics of the fluid flow in rotating helical square ducts.

  12. Manipulation of wavefront using helical metamaterials.

    Science.gov (United States)

    Yang, Zhenyu; Wang, Zhaokun; Tao, Huan; Zhao, Ming

    2016-08-01

    Helical metamaterials, a kind of 3-dimensional structure, has relatively strong coupling effect among the helical nano-wires. Therefore, it is expected to be a good candidate for generating phase shift and controlling wavefront with high efficiency. In this paper, using the finite-difference time-domain (FDTD) method, we studied the phase shift properties in the helical metamaterials. It is found that the phase shift occurs for both transmitted and reflected light waves. And the maximum of reflection coefficients can reach over 60%. In addition, the phase shift (φ) is dispersionless in the range of 600 nm to 860 nm, that is, it is only dominated by the initial angle (θ) of the helix. The relationship between them is φ = ± 2θ. Using Jones calculus we give a further explanation for these properties. Finally, by arranging the helixes in an array with a constant phase gradient, the phenomenon of anomalous refraction was also observed in a broad wavelength range.

  13. Nondispersive optical activity of meshed helical metamaterials.

    Science.gov (United States)

    Park, Hyun Sung; Kim, Teun-Teun; Kim, Hyeon-Don; Kim, Kyungjin; Min, Bumki

    2014-11-17

    Extreme optical properties can be realized by the strong resonant response of metamaterials consisting of subwavelength-scale metallic resonators. However, highly dispersive optical properties resulting from strong resonances have impeded the broadband operation required for frequency-independent optical components or devices. Here we demonstrate that strong, flat broadband optical activity with high transparency can be obtained with meshed helical metamaterials in which metallic helical structures are networked and arranged to have fourfold rotational symmetry around the propagation axis. This nondispersive optical activity originates from the Drude-like response as well as the fourfold rotational symmetry of the meshed helical metamaterials. The theoretical concept is validated in a microwave experiment in which flat broadband optical activity with a designed magnitude of 45° per layer of metamaterial is measured. The broadband capabilities of chiral metamaterials may provide opportunities in the design of various broadband optical systems and applications.

  14. Large-scale dynamics of magnetic helicity

    Science.gov (United States)

    Linkmann, Moritz; Dallas, Vassilios

    2016-11-01

    In this paper we investigate the dynamics of magnetic helicity in magnetohydrodynamic (MHD) turbulent flows focusing at scales larger than the forcing scale. Our results show a nonlocal inverse cascade of magnetic helicity, which occurs directly from the forcing scale into the largest scales of the magnetic field. We also observe that no magnetic helicity and no energy is transferred to an intermediate range of scales sufficiently smaller than the container size and larger than the forcing scale. Thus, the statistical properties of this range of scales, which increases with scale separation, is shown to be described to a large extent by the zero flux solutions of the absolute statistical equilibrium theory exhibited by the truncated ideal MHD equations.

  15. A helically distorted MHD flux rope model

    Science.gov (United States)

    Theobald, Michael L.; Montgomery, David

    1990-01-01

    A flux rope model is proposed which has a variable degree of helical distortion from axisymmetry. The basis for this suggestion is a series of numerical and analytical investigations of magnetohydrodynamic states which result when an axial electric current is directed down on dc magnetic field. The helically distorted states involve a flow velocity and seem to be favored because of their lower rate of energy dissipation. Emphasis is on the magnetometer and particle energy analyzer traces that might be characteristic of such flux ropes. It is shown that even a fractionally small helical distortion may considerably alter the traces in minimum-variance coordinates. In short, what may be fairly common MHD processes can render a flux rope almost unrecognizable under standard diagnostics, even if the departures from axisymmetry are not great.

  16. Turbulent dynamo with advective magnetic helicity flux

    CERN Document Server

    Del Sordo, Fabio; Brandenburg, Axel

    2012-01-01

    Many astrophysical bodies harbor magnetic fields that are thought to be sustained by dynamo processes. However, it has been argued that the production of large-scale magnetic fields by a mean-field dynamo is strongly suppressed at large magnetic Reynolds numbers owing to the conservation of magnetic helicity. This phenomenon is known as catastrophic quenching. Advection of magnetic field toward the outer boundaries and away from the dynamo is expected to alleviate such quenching. Examples are stellar and galactic winds. Such advection might be able to overcome the constraint imposed by the conservation of magnetic helicity, transporting a fraction of it outside the domain in which the dynamo operates. We study how the dynamo process is affected by advection. In particular, we study the relative roles played by advective and diffusive fluxes of magnetic helicity. We do this by performing direct numerical simulations of a turbulent dynamo of alpha^2 type driven by forced turbulence in a Cartesian domain in the ...

  17. Metallofoldamers supramolecular architectures from helicates to biomimetics

    CERN Document Server

    Maayan, Galia

    2013-01-01

    Metallofoldamers are oligomers that fold into three-dimensional structures in a controlled manner upon coordination with metal ions. Molecules in this class have shown an impressive ability to form single-handed helical structures and other three-dimensional architectures. Several metallofoldamers have been applied as sensors due to their selective folding when binding to a specific metal ion, while others show promise for applications as responsive materials on the basis of their ability to fold and unfold upon changes in the oxidation state of the coordinated metal ion, and as novel catalysts. Metallofoldamers: From Helicates to Biomimetic Architectures describes the variety of interactions between oligomers and metal species, with a focus on non-natural synthetic molecules. Topics covered include: the major classes of foldamers and their folding driving force metalloproteins and metalloenzymes helicates: self-assembly, structure and applications abiotic metallo-DNA metallo-PNA and iDNA metallopeptides inte...

  18. The helical structure of DNA facilitates binding

    Science.gov (United States)

    Berg, Otto G.; Mahmutovic, Anel; Marklund, Emil; Elf, Johan

    2016-09-01

    The helical structure of DNA imposes constraints on the rate of diffusion-limited protein binding. Here we solve the reaction-diffusion equations for DNA-like geometries and extend with simulations when necessary. We find that the helical structure can make binding to the DNA more than twice as fast compared to a case where DNA would be reactive only along one side. We also find that this rate advantage remains when the contributions from steric constraints and rotational diffusion of the DNA-binding protein are included. Furthermore, we find that the association rate is insensitive to changes in the steric constraints on the DNA in the helix geometry, while it is much more dependent on the steric constraints on the DNA-binding protein. We conclude that the helical structure of DNA facilitates the nonspecific binding of transcription factors and structural DNA-binding proteins in general.

  19. Demonstration of steady inductive helicity injection

    Science.gov (United States)

    Sieck, P. E.; Jarboe, T. R.; Izzo, V. A.; Hamp, W. T.; Nelson, B. A.; O'Neill, R. G.; Redd, A. J.; Smith, R. J.

    2006-02-01

    Initial results demonstrating the concept of constant inductive helicity injection are presented. Constant helicity injection is achieved using two oscillating inductive helicity injectors, with the goal of producing a bow tie spheromak. Each injector is a 180° segment of a reverse field pinch and they are driven 90° out of phase. Approximately 5 MW of power is injected during the 6 ms pulse, and the input power has been maintained at a fairly constant value by directly fuelling the injectors with neutral gas. Motivation for the experiment is given, including beta-limit calculations for the bow tie spheromak. Fuelling the injectors with neutral gas during the discharge is shown to produce injector parameters that are more constant in time. A series of discharges with increasing power input shows a promising increase in toroidal current. Unique construction techniques of the experiment are also described.

  20. Helical mode lung 4D-CT reconstruction using Bayesian model.

    Science.gov (United States)

    He, Tiancheng; Xue, Zhong; Nitsch, Paige L; Teh, Bin S; Wong, Stephen T

    2013-01-01

    4D computed tomography (CT) has been widely used for treatment planning of thoracic and abdominal cancer radiotherapy. Current 4D-CT lung image reconstruction methods rely on respiratory gating to rearrange the large number of axial images into different phases, which may be subject to external surrogate errors due to poor reproducibility of breathing cycles. New image-matching-based reconstruction works better for the cine mode of 4D-CT acquisition than the helical mode because the table position of each axial image is different in helical mode and image matching might suffer from bigger errors. In helical mode, not only the phases but also the un-uniform table positions of images need to be considered. We propose a Bayesian method for automated 4D-CT lung image reconstruction in helical mode 4D scans. Each axial image is assigned to a respiratory phase based on the Bayesian framework that ensures spatial and temporal smoothness of surfaces of anatomical structures. Iterative optimization is used to reconstruct a series of 3D-CT images for subjects undergoing 4D scans. In experiments, we compared visually and quantitatively the results of the proposed Bayesian 4D-CT reconstruction algorithm with the respiratory surrogate and the image matching-based method. The results showed that the proposed algorithm yielded better 4D-CT for helical scans.

  1. Stitched α-helical peptides via bis ring-closing metathesis.

    Science.gov (United States)

    Hilinski, Gerard J; Kim, Young-Woo; Hong, Jooyeon; Kutchukian, Peter S; Crenshaw, Charisse M; Berkovitch, Shaunna S; Chang, Andrew; Ham, Sihyun; Verdine, Gregory L

    2014-09-03

    Conformationally stabilized α-helical peptides are capable of inhibiting disease-relevant intracellular or extracellular protein-protein interactions in vivo. We have previously reported that the employment of ring-closing metathesis to introduce a single all-hydrocarbon staple along one face of an α-helical peptide greatly increases α-helical content, binding affinity to a target protein, cell penetration through active transport, and resistance to proteolytic degradation. In an effort to improve upon this technology for stabilizing a peptide in a bioactive α-helical conformation, we report the discovery of an efficient and selective bis ring-closing metathesis reaction leading to peptides bearing multiple contiguous staples connected by a central spiro ring junction. Circular dichroism spectroscopy, NMR, and computational analyses have been used to investigate the conformation of these "stitched" peptides, which are shown to exhibit remarkable thermal stabilities. Likewise, trypsin proteolysis assays confirm the achievement of a structural rigidity unmatched by peptides bearing a single staple. Furthermore, fluorescence-activated cell sorting (FACS) and confocal microscopy assays demonstrate that stitched peptides display superior cell penetrating ability compared to their stapled counterparts, suggesting that this technology may be useful not only in the context of enhancing the drug-like properties of α-helical peptides but also in producing potent agents for the intracellular delivery of proteins and oligonucleotides.

  2. Validation of a novel imaging approach using multi-slice CT and cone-beam CT to follow-up on condylar remodeling after bimaxillary surgery.

    Science.gov (United States)

    Nicolielo, Laura Ferreira Pinheiro; Van Dessel, Jeroen; Shaheen, Eman; Letelier, Carolina; Codari, Marina; Politis, Constantinus; Lambrichts, Ivo; Jacobs, Reinhilde

    2017-07-14

    The main goal of this study was to introduce a novel three-dimensional procedure to objectively quantify both inner and outer condylar remodelling on preoperative multi-slice computed tomography (MSCT) and postoperative cone-beam computed tomography (CBCT) images. Second, the reliability and accuracy of this condylar volume quantification method was assessed. The mandibles of 20 patients (11 female and 9 male) who underwent bimaxillary surgery were semi-automatically extracted from MSCT/CBCT scans and rendered in 3D. The resulting condyles were spatially matched by using an anatomical landmark-based registration procedure. A standardized sphere was created around each condyle, and the condylar bone volume within this selected region of interest was automatically calculated. To investigate the reproducibility of the method, inter- and intra-observer reliability was calculated for assessments made by two experienced radiologists twice five months apart in a set of ten randomly selected patients. To test the accuracy of the bone segmentation, the inner and outer bone structures of one dry mandible, scanned according to the clinical set-up, were compared with the gold standard, micro-CT. Thirty-eight condyles showed a significant (P0.6) intra- and inter-observer reliability was observed for both MSCT and CBCT. Moreover, the bone segmentation accuracy was less than one voxel (0.4 mm) for MSCT (0.3 mm±0.2 mm) and CBCT (0.4 mm±0.3 mm), thus indicating the clinical potential of this method for objective follow-up in pathological condylar resorption.International Journal of Oral Science advance online publication, 14 July 2017; doi:10.1038/ijos.2017.22.

  3. Current helicity and electromotive force of magnetoconvection influenced by helical background fields

    CERN Document Server

    Ruediger, Guenther

    2016-01-01

    Motivated by the empirical finding that the known hemispheric rules for the current helicity at the solar surface are not strict, the excitation of small-scale current helicity by the influence of a large-scale helical magnetic background fields on nonrotating magnetoconvection is demonstrated. It is shown within a quasilinear analytic theory of driven turbulence and by nonlinear simulations of magnetoconvection that the resulting small-scale current helicity has the same sign as the large-scale current helicity while the ratio of both pseudo-scalars is of the order of the magnetic Reynolds number of the convection. The same models do not provide finite values of the small-scale kinetic helicity. On the other hand, a turbulence-induced electromotive force is produced including the diamagnetic pumping term as well as the eddy diffusivity but no alpha effect. It is thus argued that the relations by Pouquet & Patterson (1978) and Keinigs (1983) for the simultaneous existence of small-scale current helicity a...

  4. Statistical mechanics of double-helical polymers.

    Science.gov (United States)

    De Col, Alvise; Liverpool, Tanniemola B

    2004-06-01

    We introduce a simple geometric model for a double-stranded and double-helical polymer. We study the statistical mechanics of such polymers using both analytical techniques and simulations. Our model has a single energy scale which determines both the bending and twisting rigidity of the polymer. The helix melts at a particular temperature T(c) below which the chain has a helical structure and above which this structure is disordered. Under extension we find that for small forces, the behavior is very similar to wormlike chain behavior but becomes very different at higher forces.

  5. Helicity and nuclear $\\beta$ decay correlations

    CERN Document Server

    Hong, Ran; García, Alejandro

    2016-01-01

    We present simple derivations of nuclear $\\beta$-decay correlations with an emphasis on the special role of helicity. This provides a good opportunity to teach students about helicity and chirality in particle physics through exercises using simple aspects of quantum mechanics. In addition, this paper serves as an introduction to nuclear $\\beta$-decay correlations from both a theoretical and experimental vantage. This article can be used to introduce students to ongoing experiments searching for hints of new physics in the low-energy precision frontier.

  6. Helicity and nuclear β decay correlations

    Science.gov (United States)

    Hong, Ran; Sternberg, Matthew G.; Garcia, Alejandro

    2017-01-01

    We present simple derivations of nuclear β-decay correlations with an emphasis on the special role of helicity. This topic provides a good opportunity to teach students about helicity and chirality in particle physics with exercises that use simple aspects of quantum mechanics. In addition, this paper serves as an introduction to nuclear β-decay correlations from both a theoretical and experimental perspective. This article can be used to introduce students to ongoing experiments searching for hints of new physics in the low-energy precision frontier.

  7. Helicity separation in Heavy-Ion Collisions

    CERN Document Server

    Baznat, Mircea; Sorin, Alexander; Teryaev, Oleg

    2013-01-01

    We study the P-odd effects related to the vorticity of the medium formed in noncentral heavy ion collisions. Using the kinetic Quark-Gluon Strings Model we perform the numerical simulations of the vorticity and hydrodynamical helicity for the various atomic numbers, energies and centralities. We observed the vortical structures typically occupying the relatively small fraction of the fireball volume. In the course of numerical simulations the noticeable hydrodanamical helicity was observed manifesting the specific mirror behaviour with respect to the reaction plane. The effect is maximal at the NICA and FAIR energy range.

  8. COMPUTING

    CERN Multimedia

    I. Fisk

    2011-01-01

    Introduction The Computing Team successfully completed the storage, initial processing, and distribution for analysis of proton-proton data in 2011. There are still a variety of activities ongoing to support winter conference activities and preparations for 2012. Heavy ions The heavy-ion run for 2011 started in early November and has already demonstrated good machine performance and success of some of the more advanced workflows planned for 2011. Data collection will continue until early December. Facilities and Infrastructure Operations Operational and deployment support for WMAgent and WorkQueue+Request Manager components, routinely used in production by Data Operations, are provided. The GlideInWMS and components installation are now deployed at CERN, which is added to the GlideInWMS factory placed in the US. There has been new operational collaboration between the CERN team and the UCSD GlideIn factory operators, covering each others time zones by monitoring/debugging pilot jobs sent from the facto...

  9. Conversion from mutual helicity to self-helicity observed with IRIS

    Science.gov (United States)

    Li, L. P.; Peter, H.; Chen, F.; Zhang, J.

    2014-10-01

    Context. In the upper atmosphere of the Sun observations show convincing evidence for crossing and twisted structures, which are interpreted as mutual helicity and self-helicity. Aims: We use observations with the new Interface Region Imaging Spectrograph (IRIS) to show the conversion of mutual helicity into self-helicity in coronal structures on the Sun. Methods: Using far UV spectra and slit-jaw images from IRIS and coronal images and magnetograms from SDO, we investigated the evolution of two crossing loops in an active region, in particular, the properties of the Si IV line profile in cool loops. Results: In the early stage two cool loops cross each other and accordingly have mutual helicity. The Doppler shifts in the loops indicate that they wind around each other. As a consequence, near the crossing point of the loops (interchange) reconnection sets in, which heats the plasma. This is consistent with the observed increase of the line width and of the appearance of the loops at higher temperatures. After this interaction, the two new loops run in parallel, and in one of them shows a clear spectral tilt of the Si IV line profile. This is indicative of a helical (twisting) motion, which is the same as to say that the loop has self-helicity. Conclusions: The high spatial and spectral resolution of IRIS allowed us to see the conversion of mutual helicity to self-helicity in the (interchange) reconnection of two loops. This is observational evidence for earlier theoretical speculations. Movie associated with Fig. 1 and Appendix A are available in electronic form at http://www.aanda.org

  10. Assembly of transmembrane helices of simple polytopic membrane proteins from sequence conservation patterns.

    Science.gov (United States)

    Park, Yungki; Helms, Volkhard

    2006-09-01

    The transmembrane (TM) domains of most membrane proteins consist of helix bundles. The seemingly simple task of TM helix bundle assembly has turned out to be extremely difficult. This is true even for simple TM helix bundle proteins, i.e., those that have the simple form of compact TM helix bundles. Herein, we present a computational method that is capable of generating native-like structural models for simple TM helix bundle proteins having modest numbers of TM helices based on sequence conservation patterns. Thus, the only requirement for our method is the presence of more than 30 homologous sequences for an accurate extraction of sequence conservation patterns. The prediction method first computes a number of representative well-packed conformations for each pair of contacting TM helices, and then a library of tertiary folds is generated by overlaying overlapping TM helices of the representative conformations. This library is scored using sequence conservation patterns, and a subsequent clustering analysis yields five final models. Assuming that neighboring TM helices in the sequence contact each other (but not that TM helices A and G contact each other), the method produced structural models of Calpha atom root-mean-square deviation (CA RMSD) of 3-5 A from corresponding crystal structures for bacteriorhodopsin, halorhodopsin, sensory rhodopsin II, and rhodopsin. In blind predictions, this type of contact knowledge is not available. Mimicking this, predictions were made for the rotor of the V-type Na(+)-adenosine triphosphatase without such knowledge. The CA RMSD between the best model and its crystal structure is only 3.4 A, and its contact accuracy reaches 55%. Furthermore, the model correctly identifies the binding pocket for sodium ion. These results demonstrate that the method can be readily applied to ab initio structure prediction of simple TM helix bundle proteins having modest numbers of TM helices.

  11. Multislice CT: technical principles and new trends in medical imaging and radiotherapy; Tomodensitometrie multicoupe principes techniques, nouvelles applications en imagerie et en radiotherapie

    Energy Technology Data Exchange (ETDEWEB)

    Ceugnart, L.; Taieb, S. [Centre Oscar-Lambret, Dept. d' Imagerie, 59 - Lille (France)

    2005-06-15

    Development and availability of multislice CT modifies quickly procedures for diagnostic and pre-therapeutic explorations. This new technology provides many advantages such as: to reduce time of examination and to facilitate exploration of larger anatomical volumes, to reduce partial volume effects, to enhance the ratio signal/noise, to improve intravascular concentration of contrast product and then to better identify arterial or venous phases. Use of multislice CT for exploration with respiratory gating is also discussed. On the other hand, multislice CT requires new requirements as medical time occupation and handling of important number of images. Active collaboration between radiologists and radiation oncologists is needed to define new acquisition modalities and practical ways of co-interpretation. (authors)0.

  12. Eikonal slant helices and eikonal Darboux helices in 3-dimensional pseudo-Riemannian manifolds

    OpenAIRE

    Önder, Mehmet; Ziplar, Evren

    2013-01-01

    In this study, we give definitions and characterizations of eikonal slant helices, eikonal Darboux helices and non-normed eikonal Darboux helices in 3-dimensional pseudo- Riemannian manifold M . We show that every eikonal slant helix is also an eikonal Darboux helix for timelike and spacelike curves. Furthermore, we obtain that if the non-null curve a is a non-normed eikonal Darboux helix, then a is an eikonal slant helix if and only if 2 2 e 3k +e1t = constant, where k and t are curvature an...

  13. Magnetic Energy and Helicity Budgets in the Active-Region Solar Corona. I. Linear Force-Free Approximation

    CERN Document Server

    Georgoulis, M K

    2007-01-01

    We self-consistently derive the magnetic energy and relative magnetic helicity budgets of a three-dimensional linear force-free magnetic structure rooted in a lower boundary plane. For the potential magnetic energy we derive a general expression that gives results practically equivalent to those of the magnetic Virial theorem. All magnetic energy and helicity budgets are formulated in terms of surface integrals applied to the lower boundary, thus avoiding computationally intensive three-dimensional magnetic field extrapolations. We analytically and numerically connect our derivations with classical expressions for the magnetic energy and helicity, thus presenting a so-far lacking unified treatment of the energy/helicity budgets in the constant-alpha approximation. Applying our derivations to photospheric vector magnetograms of an eruptive and a noneruptive solar active regions, we find that the most profound quantitative difference between these regions lies in the estimated free magnetic energy and relative ...

  14. Energy and helicity budgets of solar quiet regions

    CERN Document Server

    Tziotziou, K; Georgoulis, M K; Kontogiannis, I

    2014-01-01

    We investigate the free magnetic energy and relative magnetic helicity budgets of solar quiet regions. Using a novel non-linear force-free method requiring single solar vector magnetograms we calculate the instantaneous free magnetic energy and relative magnetic helicity budgets in 55 quiet-Sun vector magnetograms. As in a previous work on active regions, we construct here for the first time the (free) energy-(relative) helicity diagram of quiet-Sun regions. We find that quiet-Sun regions have no dominant sense of helicity and show monotonic correlations a) between free magnetic energy/relative helicity and magnetic network area and, consequently, b) between free magnetic energy and helicity. Free magnetic energy budgets of quiet-Sun regions represent a rather continuous extension of respective active-region budgets towards lower values, but the corresponding helicity transition is discontinuous due to the incoherence of the helicity sense contrary to active regions. We further estimate the instantaneous free...

  15. Helical mode interactions and spectral transfer processes in magnetohydrodynamic turbulence

    CERN Document Server

    Linkmann, Moritz F; McKay, Mairi E; Jäger, Julia

    2015-01-01

    Spectral transfer processes in magnetohydrodynamic (MHD) turbulence are investigated analytically by decomposition of the velocity and magnetic fields in Fourier space into helical modes. Steady solutions of the dynamical system which governs the evolution of the helical modes are determined, and a stability analysis of these solutions is carried out. The interpretation of the analysis is that unstable solutions lead to energy transfer between the interacting modes while stable solutions do not. From this, a dependence of possible interscale energy and helicity transfers on the helicities of the interacting modes is derived. As expected from the inverse cascade of magnetic helicity in 3D MHD turbulence, mode interactions with like helicities lead to transfer of energy and magnetic helicity to smaller wavenumbers. However, some interactions of modes with unlike helicities also contribute to an inverse energy transfer. As such, an inverse energy cascade for nonhelical magnetic fields is shown to be possible. Fu...

  16. COMPUTING

    CERN Multimedia

    M. Kasemann

    CMS relies on a well functioning, distributed computing infrastructure. The Site Availability Monitoring (SAM) and the Job Robot submission have been very instrumental for site commissioning in order to increase availability of more sites such that they are available to participate in CSA07 and are ready to be used for analysis. The commissioning process has been further developed, including "lessons learned" documentation via the CMS twiki. Recently the visualization, presentation and summarizing of SAM tests for sites has been redesigned, it is now developed by the central ARDA project of WLCG. Work to test the new gLite Workload Management System was performed; a 4 times increase in throughput with respect to LCG Resource Broker is observed. CMS has designed and launched a new-generation traffic load generator called "LoadTest" to commission and to keep exercised all data transfer routes in the CMS PhE-DEx topology. Since mid-February, a transfer volume of about 12 P...

  17. Synthesis of stabilized alpha-helical peptides.

    Science.gov (United States)

    Bernal, Federico; Katz, Samuel G

    2014-01-01

    Stabilized alpha-helical (SAH) peptides are valuable laboratory tools to explore important protein-protein interactions. Whereas most peptides lose their secondary structure when isolated from the host protein, stapled peptides incorporate an all-hydrocarbon "staple" that reinforces their natural alpha-helical structure. Thus, stapled peptides retain their functional ability to bind their native protein targets and serve multiple experimental uses. First, they are useful for structural studies such as NMR or crystal structures that map and better define binding sites. Second, they can be used to identify small molecules that specifically target that interaction site. Third, stapled peptides can be used to test the importance of specific amino acid residues or posttranslational modifications to the binding. Fourth, they can serve as structurally competent bait to identify novel binding partners to specific alpha-helical motifs. In addition to markedly improved alpha-helicity, stapled peptides also display resistance to protease cleavage and enhanced cell permeability. Most importantly, they are useful for intracellular experiments that explore the functional consequences of blocking particular protein interactions. Because of their remarkable stability, stapled peptides can be applied to whole-animal, in vivo studies. Here we describe a protocol for the synthesis of a peptide that incorporates an all-hydrocarbon "staple" employing a ring-closing olefin metathesis reaction. With proper optimization, stapled peptides can be a fundamental, accurate laboratory tool in the modern chemical biologist's armory.

  18. LAMINAR FLUID FLOW IN HELICAL ELLIPTICAL PIPE

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In this paper, using an orthogonal curvilinear coordinate system and solving the complete N-S equations, we analyzed the flow in a helical elliptical duct by the perturbation method. The first-order solutions of the stream function Ψ, axial velocity w and the velocity of secondary flow (u, v) were obtained. The effects of torsion, curvature and the axial pressure gradient on the secondary flow were discussed in detail. The study indicates that the torsion has first-order effect on the secondary flow in a helical elliptical pipe, the secondary flow is dominated by torsion when the axial pressure gradient is small and for increasing gradient the secondary flow is eventually dominated by the effect due to curvature. The fact that the torsion has no effect on fluid flow in a helical pipe with a circular cross section was also confirmed. The most important conclusion is that the flow in a helical elliptical pipe to the first-order can be obtained as a combination of the flow in a toroidal pipe and the flow in a twisted pipe.

  19. On statistical equilibrium in helical fluid flows

    Directory of Open Access Journals (Sweden)

    M. V. Kurgansky

    2006-01-01

    Full Text Available The statistical mechanics of 3-D helical flows is re-examined for a continuum truncated at a top wavenumber. Based on the principle of equipartition of the flow enstrophy between helical modes, the emerging (i energy spectrum law '–2' and (ii formal mathematical analogy between the helicity and the thermodynamic entropy are discussed. It is noted that the '–2' scaling law is consistent with both spectral equilibrium and spectral cascade paradigms. In an attempt to apply the obtained results to a turbulent flow regime within the Earth's outer liquid core, where the net helicity of a turbulent flow component is presumably explained by Earth's rotation, it has been noticed that it is the energy spectral law '–1', but not '–2', which is likely realized there and within the logarithmic accuracy corresponds to the case of the velocity structure function [u(l]2 independency on the spatial scale l, the latter is consistent with observations. It is argued that the '–1' scaling law can also be interpreted in terms of the spectral equilibrium and it is emphasized that the causes of the likely dominance of the spectral law '–1' over the spectral law '–2' in this geophysical application deserve further investigation and clarification.

  20. Coulomb drag between helical Luttinger liquids

    Science.gov (United States)

    Kainaris, N.; Gornyi, I. V.; Levchenko, A.; Polyakov, D. G.

    2017-01-01

    We theoretically study Coulomb drag between two helical edges with broken spin-rotational symmetry, such as would occur in two capacitively coupled quantum spin Hall insulators. For the helical edges, Coulomb drag is particularly interesting because it specifically probes the inelastic interactions that break the conductance quantization for a single edge. Using the kinetic equation formalism, supplemented by bosonization, we find that the drag resistivity ρD exhibits a nonmonotonic dependence on the temperature T . In the limit of low T ,ρD vanishes with decreasing T as a power law if intraedge interactions are not too strong. This is in stark contrast to Coulomb drag in conventional quantum wires, where ρD diverges at T →0 irrespective of the strength of repulsive interactions. Another unusual property of Coulomb drag between the helical edges concerns higher T for which, unlike in the Luttinger liquid model, drag is mediated by plasmons. The special type of plasmon-mediated drag can be viewed as a distinguishing feature of the helical liquid—because it requires peculiar umklapp scattering only available in the presence of a Dirac point in the electron spectrum.

  1. Helical Gears Modified To Decrease Transmission Errors

    Science.gov (United States)

    Handschuh, R. F.; Coy, J. J.; Litvin, F. L.; Zhang, J.

    1993-01-01

    Tooth surfaces of helical gears modified, according to proposed design concept, to make gears more tolerant of misalignments and to improve distribution of contact stresses. Results in smaller transmission errors, with concomitant decreases in vibrations and noise and, possibly, increases in service lives.

  2. Helical Ordering in Chiral Block Copolymers

    Science.gov (United States)

    Zhao, Wei; Hong, Sung Woo; Chen, Dian; Grason, Gregory; Russell, Thomas

    2012-02-01

    Introducing molecular chirality into the segments of block copolymers can influence the nature of the resultant morphology. Such an effect was found for poly(styrene-b-L-lactide) (PS-b-PLLA) diblock copolymers where hexagonally packed PLLA helical microdomains (H* phase) form in a PS matrix. However, molecular ordering of PLLA within the helical microdomains and the transfer of chirality from the segmental level to the mesoscale is still not well understood. We developed a field theoretic model to describe the interactions between segments of chiral blocks, which have the tendency to form a ``cholesteric'' texture. Based on the model, we calculated the bulk morphologies of chiral AB diblock copolymers using self-consistent field theory (SCFT). Experiments show that the H* phase only forms when microphase separation between PS and PLLA block happens first and crystallization of PLLA block is suppressed or happens within confined microdomain. Hence, crystalline ordering is not necessary for H* phase formation. The SCFT offers the chance to explore the range of thermodynamic stability of helical structures in the phase diagram of chiral block copolymer melts, by tuning parameters not only like the block segregation strength and composition, but also new parameters such as the ratio between preferred helical pitch to the radius of gyration and the Frank elastic constant for inter-segment distortions.

  3. Magnetic stripes and skyrmions with helicity reversals.

    Science.gov (United States)

    Yu, Xiuzhen; Mostovoy, Maxim; Tokunaga, Yusuke; Zhang, Weizhu; Kimoto, Koji; Matsui, Yoshio; Kaneko, Yoshio; Nagaosa, Naoto; Tokura, Yoshinori

    2012-06-05

    It was recently realized that topological spin textures do not merely have mathematical beauty but can also give rise to unique functionalities of magnetic materials. An example is the skyrmion--a nano-sized bundle of noncoplanar spins--that by virtue of its nontrivial topology acts as a flux of magnetic field on spin-polarized electrons. Lorentz transmission electron microscopy recently emerged as a powerful tool for direct visualization of skyrmions in noncentrosymmetric helimagnets. Topologically, skyrmions are equivalent to magnetic bubbles (cylindrical domains) in ferromagnetic thin films, which were extensively explored in the 1970s for data storage applications. In this study we use Lorentz microscopy to image magnetic domain patterns in the prototypical magnetic oxide-M-type hexaferrite with a hint of scandium. Surprisingly, we find that the magnetic bubbles and stripes in the hexaferrite have a much more complex structure than the skyrmions and spirals in helimagnets, which we associate with the new degree of freedom--helicity (or vector spin chirality) describing the direction of spin rotation across the domain walls. We observe numerous random reversals of helicity in the stripe domain state. Random helicity of cylindrical domain walls coexists with the positional order of magnetic bubbles in a triangular lattice. Most unexpectedly, we observe regular helicity reversals inside skyrmions with an unusual multiple-ring structure.

  4. Muon Beam Helical Cooling Channel Design

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Rolland; Ankenbrandt, Charles; Flanagan, G; Kazakevich, G M; Marhauser, Frank; Neubauer, Michael; Roberts, T; Yoshikawa, C; Derbenev, Yaroslav; Morozov, Vasiliy; Kashikhin, V S; Lopes, Mattlock; Tollestrup, A; Yonehara, Katsuya; Zloblin, A

    2013-06-01

    The Helical Cooling Channel (HCC) achieves effective ionization cooling of the six-dimensional (6d) phase space of a muon beam by means of a series of 21st century inventions. In the HCC, hydrogen-pressurized RF cavities enable high RF gradients in strong external magnetic fields. The theory of the HCC, which requires a magnetic field with solenoid, helical dipole, and helical quadrupole components, demonstrates that dispersion in the gaseous hydrogen energy absorber provides effective emittance exchange to enable longitudinal ionization cooling. The 10-year development of a practical implementation of a muon-beam cooling device has involved a series of technical innovations and experiments that imply that an HCC of less than 300 m length can cool the 6d emittance of a muon beam by six orders of magnitude. We describe the design and construction plans for a prototype HCC module based on oxygen-doped hydrogen-pressurized RF cavities that are loaded with dielectric, fed by magnetrons, and operate in a superconducting helical solenoid magnet.

  5. Artificial, parallel, left-handed DNA helices.

    Science.gov (United States)

    Tian, Cheng; Zhang, Chuan; Li, Xiang; Li, Yingmei; Wang, Guansong; Mao, Chengde

    2012-12-19

    This communication reports an engineered DNA architecture. It contains multiple domains of half-turn-long, standard B-DNA duplexes. While each helical domain is right-handed and its two component strands are antiparallel, the global architecture is left-handed and the two component DNA strands are oriented parallel to each other.

  6. Review of the helicity formalism; Revision del formalismo de helicidad

    Energy Technology Data Exchange (ETDEWEB)

    Barreiro, F.; Cerrada, M.; Fernandez, E.

    1972-07-01

    Our purpose in these notes has been to present a brief and general review of the helicity formalism. We begin by discussing Lorentz invariance, spin and helicity ideas, in section 1 . In section 2 we deal with the construction of relativistic states and scattering amplitudes in the helicity basis and we study their transformation properties under discrete symmetries. Finally we present some more sophisticated topics like kinematical singularities of helicity amplitudes, kinematical constraints and crossing relations 3, 4, 5 respectively. (Author) 8 refs.

  7. Electromagnetic helicity wavelets: a model for quasar engines?

    CERN Document Server

    Kaiser, Gerald

    2012-01-01

    The complex distance function $\\zeta$, which plays a prominent role in the definition of scalar (acoustic) wavelets, is found to determine a complex extension of the spherical coordinate system that is ideally suited for the construction of highly focused electromagnetic beams with helicities conforming to the oblate spheroidal geometry of $\\zeta$. This is used to build a basis of electromagnetic wavelets $F^m$ radiated or absorbed by the branch disk $D$ of $\\zeta$. $F^m$ has integer angular momentum $m$ around the z axis and definite spheroidal helicity. We use a regularization method to compute its singular charge-current density and show that the total charge vanishes. Hence $F^m$ is due solely to electric and magnetic polarization currents. $D$ acts as a magnetic dipole antenna, and its axis as a coupled electric dipole antenna. We propose this as an idealized electromagnetic model for quasars (in flat spacetime, without gravity), with $D$ representing the accretion disk and the vortex singularities along...

  8. [Detection of coronary calcifications by electron beam tomography and multislice spiral CT: clinical relevance].

    Science.gov (United States)

    Achenbach, S; Schmermund, A; Erbel, R; Silber, S; Haberl, R; Moshage, W; Daniel, W G

    2003-11-01

    Coronary calcifications can be detected and quantified using electron beam tomography (EBT) or newer generation multi-slice spiral CT (MSCT) scanners. An abundance of data has been acquired by EBT. It could be shown that the amount of coronary calcium correlates to the coronary plaque burden. The detection of coronary calcium with CT imaging methods therefore provides a unique opportunity to detect and quantify coronary atherosclerosis in a subclinical stage. Consequently, the presence and amount of coronary calcium has been shown to be indicative for an increased coronary event risk in symptomatic and asymptomatic individuals. Several clinical studies found a predictive value that was superior to conventional risk factors. Clinically, the use of coronary calcification assessment may therefore be beneficial in patients who, based on traditional risk factors, seem to be at "intermediate risk" for coronary events (10-year event risk 10-20%) in order to decide on the aggressiveness of risk factor modification. The role of coronary calcium quantification to monitor the progression of disease has not been clarified yet. Large, ongoing trials will provide further data as to the relative merit of coronary calcium assessment for risk stratification and will help to more clearly define its clinical role. The relationship between coronary calcium and coronary stenoses is more complex. While the absence of coronary calcifications makes significant coronary stenoses unlikely, even large amounts of coronary calcium do not necessarily indicate the presence of coronary artery stenoses. Pronounced coronary calcifications as an isolated finding should therefore not be the motivation for invasive diagnostic procedures in the absence of other evidence of ischemic heart disease.

  9. [Diagnostic value of multi-slice spiral computerized tomographic fistulography in congenital fistula of neck].

    Science.gov (United States)

    Zheng, H; Ye, Q; Wang, X Y; Zheng, X H; Yang, X Q; Chen, Y; Jiang, Y; Li, R Y

    2017-08-07

    Objective: To investigate the usefulness and effectiveness of multi-slice spiral computerized tomographic fistulography (MSCTF) in the diagnosis and treatment of congenital fistula of neck. Methods: Thirty-four patients with thyroglossal fistulasor branchial cleft fistulas who were initial treated from July 2008 to August 2015 in Fujian Provincial Hospital were retrospectively analyses. Thirteen males and 21 females patients aging from 3 to 46 years old with a median age of 37 were included. There were thyroglossal fistula in 6 cases, the first branchialcleft fistula in 9 cases, the second branchialcleft fistula in 3 cases, the third branchialcleft fistula in 9 cases, and the fourth branchialcleft fistula in 7 cases. All the patients underwent preopeative MSCTF and the diagnoses were finally confirmed with surgery and histopathology. Multiplanar reconstruction(MPR), maximumintensity projection(MIP)and volume rendering(VR) were completed with AW Volume Share 4.2 image processing software after initial CT scanning.The internal openings, distribution, and neighboring relationship of the fistulas showed by MSCTF were analyzed and the surgical strategies were subsequently made. Results: Except 2 cases, 32 patients had obtained successfully MSCTF image. The presence and location of the fistulas could be showed clearly on MSCTF. Based on the results of MSCTF examination, the surgical planes to treat the fistulas were made. The fistulas in all cases were successfully found and excised. Three cases underwent selective neck dissection. Postoperative infection occurred in 1 case. Unilateral vocal fold paralysis due to surgery recovered 3 months after surgery with follow-up. One case lost follow-up, the remaining 33 cases were followed up for 13-97 months with no the fistula recurrence. Conclusions: MSCTF could provide valuable information and benefit surgical planning by demonstrating the coursesof congenital fistulas of neck in detail.

  10. Contrast-enhanced multislice pneumo-CT-cystography in the evaluation of urinary bladder neoplasms

    Energy Technology Data Exchange (ETDEWEB)

    Scardapane, Arnaldo [Institute of Diagnostic Radiology, University Hospital ' Policlinico' , Bari (Italy)], E-mail: scardapane@aruba.it; Pagliarulo, Vincenzo [Institute of Urology, University Hospital ' Policlinico' , Bari (Italy); Ianora, Amato A. Stabile [Institute of Diagnostic Radiology, University Hospital ' Policlinico' , Bari (Italy); Pagliarulo, Arcangelo [Institute of Urology, University Hospital ' Policlinico' , Bari (Italy); Angelelli, Giuseppe [Institute of Diagnostic Radiology, University Hospital ' Policlinico' , Bari (Italy)

    2008-05-15

    Purpose: To evaluate the accuracy of contrast-enhanced multislice CT (MSCT) in the study of urothelial tumors after distension of the bladder with air. Materials and methods: We evaluated 43 consecutive patients with endoscopically proven bladder lesions. After air distension of the bladder, unenhanced pelvic and enhanced abdomino-pelvic scans were obtained with the following protocol: thickness 2.5 mm x 4 mm, increment 1 mm, scan delay 40'' and 7-10 min. For each patient we considered the number, size, aspect (papillary or sessile) and contrast enhancement of lesions. Ureteral involvement and the presence of synchronous lesions in the excretory scan were also evaluated. MPR and virtual endoscopy images were reviewed in all cases. Results: Bladder lesions were visualized in 39/43 cases. Compared to conventional cystoscopy, MSCT recognized single lesions in 31/33 patients, two lesions in 4/6, three in 2/2 and more than five foci in 2/2 patients. A papillary aspect was described in 44 cases while 11 lesions were sessile. Conventional Cystoscopy recognized six more lesions as compared with MSCT (four flat and two small papillary lesions). The detection rate for protruding lesions was 100% (52/52) for lesions > 5 mm and 60% (3/5%) for lesions < 5 mm. In four patients hydronephrosis was present, while in one case a synchronous lesion was evident in the renal pelvis. Conclusion: Contrast-enhanced MSCT with air distension of the urinary bladder is a safe and complete investigation to evaluate the local stage of bladder cancer and to evaluate the ureteral extension of the tumor, as well as the presence of synchronous lesions.

  11. 术前应用螺旋CT个体化测量在骶髂关节置钉中的意义%The significance of individual measuring by preoperatively application of helical computed tomography in the placement of screw on the sacroiliac joint

    Institute of Scientific and Technical Information of China (English)

    刘新园; 黄继锋; 刘忠; 赵卫东; 田龙海; 段连鸿

    2011-01-01

    Objective To explore the feasibility of individual measuring the parameters of the screwing trajectory of the screw on the uninjured side by application of helical computed tomography before open reduction and internal fixation using sacroiliac screw to guide the placement of screw on the injured side.Methods (1) Ten fiozen pelvic specimens of normal Chinese adults were scanned and multiplanarly reconstructed by helical computed tomography in order to measure the entrance direction of the S1 screw, the distance fiom the entry point to the posterior superior iliac spine and the posterior inferior iliac spine, the length,and safe angle of the screwing trajectory as well. (2) The left and right sacroiliac joints of eight pelvic specimens were made into vertical unstable model. Then, the left sacroiliac joints were individually validated by the iliosacral screws according to the measurement result of the screw trajectory scanned by CT on the right sacroiliac joints, and the right sacroiliac joints by the measurement results of the screw trajectory on the left side. Results (l)The direction of screw was (25.95±1.39)° to the coronal plane, and (19.61±2.97)° to the horizontal plane. The distance from the entry point was (37.17±2.90) mm to posterior superior iliac spine, and (38.23±1.69) mm to the posterior inferior iliac spine. The safe angle of the screw trajectory was( 19.87±1.61 )°to the coronal plane, and (23.84±2.08)° to the axial plane. (2)All of the ten inserted iliosacral screws of the left sacroiliac joints inserted were entirely within the pedicle; In the right side, except one deviated out of the bone,other nine cases were entirely within the pedicle. Conclusions The method through individual measuring the parameters of the screwing trajectory of the screw on the uninjured side by application of helical computed tomography before open reduction and internal fixation using sacroiliac screw to guide the placement of screw on the injured side has been

  12. Three-dimensional printing of freeform helical microstructures: a review

    Science.gov (United States)

    Farahani, R. D.; Chizari, K.; Therriault, D.

    2014-08-01

    Three-dimensional (3D) printing is a fabrication method that enables creation of structures from digital models. Among the different structures fabricated by 3D printing methods, helical microstructures attracted the attention of the researchers due to their potential in different fields such as MEMS, lab-on-a-chip systems, microelectronics and telecommunications. Here we review different types of 3D printing methods capable of fabricating 3D freeform helical microstructures. The techniques including two more common microfabrication methods (i.e., focused ion beam chemical vapour deposition and microstereolithography) and also five methods based on computer-controlled robotic direct deposition of ink filament (i.e., fused deposition modeling, meniscus-confined electrodeposition, conformal printing on a rotating mandrel, UV-assisted and solvent-cast 3D printings) and their advantages and disadvantages regarding their utilization for the fabrication of helical microstructures are discussed. Focused ion beam chemical vapour deposition and microstereolithography techniques enable the fabrication of very precise shapes with a resolution down to ~100 nm. However, these techniques may have material constraints (e.g., low viscosity) and/or may need special process conditions (e.g., vacuum chamber) and expensive equipment. The five other techniques based on robotic extrusion of materials through a nozzle are relatively cost-effective, however show lower resolution and less precise features. The popular fused deposition modeling method offers a wide variety of printable materials but the helical microstructures manufactured featured a less precise geometry compared to the other printing methods discussed in this review. The UV-assisted and the solvent-cast 3D printing methods both demonstrated high performance for the printing of 3D freeform structures such as the helix shape. However, the compatible materials used in these methods were limited to UV-curable polymers and

  13. Helicity of Solar Active Regions from a Dynamo Model

    Indian Academy of Sciences (India)

    Piyali Chatterjee

    2006-06-01

    We calculate helicities of solar active regions based on the idea that poloidal flux lines get wrapped around a toroidal flux tube rising through the convection zone, thereby giving rise to the helicity. We use our solar dynamo model based on the Babcock–Leighton -effect to study how helicity varies with latitude and time.

  14. Sign of helicity in the alpha-Omega geodynamo

    CERN Document Server

    Wei, Xing

    2010-01-01

    In this paper we investigate the sign of helicity in the alpha-Omega dynamo and point out that the alpha effect in the geodynamo is induced by helical wave but not helical flow as in the solar dynamo. We then postulate the mechanisms of the Earth's magnetic tilt angle, westward drift and dipole reversals.

  15. Field-theoretic calculation of kinetic helicity flux

    Indian Academy of Sciences (India)

    V Avinash; Mahendra K Verma; Amar K Chandra

    2006-02-01

    In this paper we apply perturbative field-theoretic technique to helical turbulence. In the inertial range the kinetic helicity flux is found to be constant and forward. The universal constant H appearing in the spectrum of kinetic helicity was found to be 2.47.

  16. The Effects of Spatial Smoothing on Solar Magnetic Helicity and the Hemispheric Helicity Sign Rule

    Science.gov (United States)

    Koch Ocker, Stella; Petrie, Gordon

    2016-05-01

    The hemispheric sign rule for solar magnetic helicity, which states that negative/positive helicity occurs preferentially in the northern/southern hemisphere, provides clues to the causes of twisted, flaring magnetic fields. However, previous studies on the hemisphere rule may have been significantly affected by seeing from atmospheric turbulent motions. Using Hinode/SOT-SP data spanning from 2006 to 2012, we studied the effects of two important data processing steps that imitate the effects of atmospheric seeing: noise reduction by ignoring pixel values that are weaker than the estimated noise threshold, and Gaussian spatial smoothing. We applied these processing techniques to the helicity distribution maps for active regions NOAA 11158 and NOAA 11243, along with the average helicities of 36 active regions, in order to imitate and understand the effects of seeing from atmospheric turbulence. We found that rather than changing trends in the helicity distributions, Gaussian smoothing and noise reduction enhanced existing trends by pushing outliers towards the mean or removing them altogether. We also found that, when separated for weak and strong magnetic fields, the average helicities of the 36 active regions conformed to the hemisphere rule for weak field helicities and breached the rule for strong field helicities. In general, we found that data processing did not affect whether the hemisphere rule held for data taken from space-based instruments, and thus that seeing from atmospheric turbulence did not significantly affect previous studies' ground-based results on the hemisphere rule. This work was carried out through the National Solar Observatory Research Experiences for Undergraduates (REU) Program, which is funded by the National Science Foundation (NSF). The National Solar Observatory is operated by the Association of Universities for Research in Astronomy, Inc. (AURA) under cooperative agreement with the NSF.

  17. Cardiac imaging by means of four-detector row computed tomography and cardiac gating; Imagerie cardiaque en tomodensitometrie a quatre canaux d'acquisition et synchronisation cardiaque

    Energy Technology Data Exchange (ETDEWEB)

    Ketelslegers, E.; Coche, E.; Goffette, P.; Maldague, B.; Be, Van Beers [Clinique Universitaires UCL Saint-Luc, Bruxelles (Belgium); Gerber, B. [Clinique Universitaires UCL Saint-Luc, Dept. d' Imagerie Medicale, Bruxelles (Belgium)

    2003-09-01

    Electrocardiographically-assisted imaging is a recent development in multislice spiral computed tomography, In this article, we summarize the principles of four-detector row CT for cardiac applications. Following is an overview of the potential of this technique to evaluate the heart, the thoracic aorta, and the para-cardiac pulmonary parenchyma. Technical considerations for optimal imaging are highlighted. (authors)

  18. What Helicity Can Tell Us about Solar Magnetic Fields

    Indian Academy of Sciences (India)

    Alexei A. Pevtsov

    2008-03-01

    Concept of magnetic/current helicity was introduced to solar physics about 15 years ago. Earlier studies led to discovery of such fundamental properties as hemispheric helicity rule, and role of helicity in magnetic reconnection and solar eruptions. Later, the concept was successfully applied in studies of different solar processes from solar dynamo to flare and CME phenomena. Although no silver bullet, helicity has proven to be a very useful “tool” in answering many still-puzzling questions about origin and evolution of solar magnetic fields. I present an overview of some helicity studies and briefly analyze their findings.

  19. Ion temperature gradient modes in toroidal helical systems

    Energy Technology Data Exchange (ETDEWEB)

    Kuroda, T. [Graduate University for Advanced Studies, Toki, Gifu (Japan); Sugama, H.; Kanno, R.; Okamoto, M.

    2000-04-01

    Linear properties of ion temperature gradient (ITG) modes in helical systems are studied. The real frequency, growth rate, and eigenfuncti