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Sample records for helical ct appearance

  1. Helical CT appearance of hypovascular small hepatocellular carcinoma with pathologic correlation

    International Nuclear Information System (INIS)

    Zheng Keguo; Xu Dasheng; Shen Jingxian

    2003-01-01

    Objective: To study the helical CT dual-phase enhancement manifestation of the hypodense small hepatocellular carcinoma, and to evaluate its correlation with the histopathology. Methods: The CT signs and its histopathologic changes were analyzed in 25 cases with 27 hypodense lesions in helical CT dual-phase enhancement. All the lesions were confirmed as small hepatocellular carcinoma by operation and histopathology. Results: (1) On unenhanced scan, 16 lesions were with obscure borders and 11 lesions were with well-delineated borders. On enhanced scan, only 7 lesions were with obscure borders and the other 20 lesions were with well-delineated borders, and their contours were slightly irregular. (2) On unenhanced scan, 18 lesions showed homogeneous hypodensity and 9 lesions showed heterogeneous hypodensity. On enhanced scan, only 6 lesions showed homogeneous hypodensity and the other 21 lesions showed heterogeneous hypodensity with multiple flecks of more hypodense areas. Conclusion: The helical CT dual-phase enhancement characteristic manifestations of hypodense small hepatocellular carcinoma were as follows: the border of the lesion was obscure on unenhanced scan, however the border of the lesion became well-delineated and slightly irregular, and there were multiple flecks of more hypodense areas in the lesions after enhancement. This might be an important character in distinguishing hypodense small hepatocellular carcinoma from other hypodense diseases in the liver

  2. Helical CT defecography

    International Nuclear Information System (INIS)

    Ferrando, R.; Fiorini, G.; Beghello, A.; Cicio, G.R.; Derchi, L.E.; Consigliere, M.; Resasco, M.; Tornago, S.

    1999-01-01

    The purpose of this work is to investigate the possible role of Helical CT defecography in pelvic floor disorders by comparing the results of the investigations with those of conventional defecography. The series analyzed consisted of 90 patients, namely 62 women and 28 men, ranging in age 24-82 years. They were all submitted to conventional defecography, and 18 questionable cases were also studied with Helical CT defecography. The conventional examination was performed during the 4 standard phases of resting, squeezing, Valsalva and straining; it is used a remote-control unit. The parameters for Helical CT defecography were: 5 mm beam collimation, pitch 2, 120 KV, 250 m As and 18-20 degrees gantry inclination to acquire coronal images of the pelvic floor. The rectal ampulla was distended with a bolus of 300 mL nonionic iodinated contrast agent (dilution: 3g/cc). The patient wore a napkin and was seated on the table, except for those who could not hold the position and were thus examined supine. Twenty-second helical scans were performed at rest and during evacuation; multiplanar reconstructions were obtained especially on the sagittal plane for comparison with conventional defecographic images. Coronal Helical CT defecography images permitted to map the perineal floor muscles, while sagittal reconstructions provided information on the ampulla and the levator ani. To conclude, Helical CT defecography performed well in study of pelvic floor disorders and can follow conventional defecography especially in questionable cases [it

  3. CT appearance of splenosis

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    Mendelson, D.S.; Cohen, B.A.; Armas, R.R.

    1982-12-01

    Splenosis is an unusual complication of splenic trauma. The computed tomographic (CT) appearance of splenosis is described. One should consider this diagnosis when faced with a history of splenic trauma and multiple round or oval masses at CT.

  4. CT appearance of splenosis

    International Nuclear Information System (INIS)

    Mendelson, D.S.; Cohen, B.A.; Armas, R.R.

    1982-01-01

    Splenosis is an unusual complication of splenic trauma. The computed tomographic (CT) appearance of splenosis is described. One should consider this diagnosis when faced with a history of splenic trauma and multiple round or oval masses at CT

  5. Tuberculous peritonitis: CT appearance

    International Nuclear Information System (INIS)

    Hanson, R.D.; Hunter, T.B.

    1985-01-01

    Rare, sporadic cases of tuberculous peritonitis do occur in the United States and other advanced countries. Because there are few descriptions of the CT appearance of the peritoneal forms of tuberculous (TB), this report illustrates a case of tuberculous peritonitis with prominent CT findings and discusses the differentiation of this entity from other, more common diseases

  6. Clinical application of helical CT colonography

    International Nuclear Information System (INIS)

    Zeng Huiliang; Zhu Xinjin; Liang Rujian; Liang Jianhao; Ou Weiqian; Wen Haomao

    2009-01-01

    Objective: To investigate the clinical value of 16-slice helical CT colonography in the diagnosis of colon tumor and polypus. Methods: 16-slice helical CT volumetric scanning was performed in 18 patients with colonic disease, including colonic tumor (n=16) and colonic polypus (n=2). 3D images, virtual endoscopy and multiplanar reformation were obtained in the AW4.1 workstation. CT appearances were compared with operation and fiberoptic colonoscopy. Results: Satisfied results were achieved from 18 patients, no difference found in results between CT colonography and operation in 16 patients with colonic tumor. Conclusion: 16-slice helical CT colonography is of great value in preoperative staging of colonic tumor and have a high value in clinical application. (authors)

  7. Helical CT of ureteral disease

    International Nuclear Information System (INIS)

    Cikman, Pablo; Bengio, Ruben; Bulacio, Javier; Zirulnik, Esteban; Garimaldi, Jorge

    2000-01-01

    Among the new applications of helical CT is the study of the ureteral pathology. The objective of this paper was to evaluate patients with suspected pathology of this organ and the repercussion in the therapeutic plans. We studied 23 patients with a helical CT protocol, without IV contrast injection and performed multiplanar reconstruction (MPR). We called this procedure Pielo CT. Thirteen ureteral stones were detected, 6 calculi, 2 urinary tract tumors, dilatation of the system in a patient with neo-bladder. In 2 patients, in whom ureteral pathology was ruled out, we found other alterations that explained the symptoms, (gallbladder stones, disk protrusion). The Pielo CT let decide a therapeutical approach in 20 or 21 patients with ureteral pathology. (author)

  8. CT appearance of juvenile angiofibroma

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    Ueda, Jun; Hara, Kazuo (Sumitomo Hospital, Osaka (Japan)); Fukuzumi, Akio; Uchida, Hideo

    1983-06-01

    Three verified cases of juvenile angiofibroma were presented. All of them were young and adolescent male CT proved to be an ideal tool in evaluating the extension of this tumor. The appearance on plain CT was multilobulated with displacement of the adjacent bony structures. On enhancement, there was intense staining of the tumor.

  9. CT appearance of pulmonary ligament

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    Im, Jung Gi; Han, Man Chung; Chin, Soo Yil [Seoul National University College of Medicine, Seoul (Korea, Republic of)

    1984-03-15

    Pulmonary ligament consists of 2 serosal of pleura that connect the lower to the mediastinum. Author analyse and present CT appearance of pulmonary ligament of the 40 normal and abnormal patients on the basis of anatomic knowledge from the cross section of cadaver. Left pulmonary ligament is more frequency visualized than the right. The most important CT landmark in localizing pulmonary ligament is the esophagus where the ligament attaches on its lateral wall. Pitfalls in CT identification of pulmonary ligament are right phrenic nerve and right pericardiacophrenic vessels which emerge from lateral wall of the IVC and wall of the emphysematous bulla in the region of the pulmonary ligament.

  10. CT appearance of pulmonary ligament

    International Nuclear Information System (INIS)

    Im, Jung Gi; Han, Man Chung; Chin, Soo Yil

    1984-01-01

    Pulmonary ligament consists of 2 serosal of pleura that connect the lower to the mediastinum. Author analyse and present CT appearance of pulmonary ligament of the 40 normal and abnormal patients on the basis of anatomic knowledge from the cross section of cadaver. Left pulmonary ligament is more frequency visualized than the right. The most important CT landmark in localizing pulmonary ligament is the esophagus where the ligament attaches on its lateral wall. Pitfalls in CT identification of pulmonary ligament are right phrenic nerve and right pericardiacophrenic vessels which emerge from lateral wall of the IVC and wall of the emphysematous bulla in the region of the pulmonary ligament

  11. Normal pediatric postmortem CT appearances

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    Klein, Willemijn M.; Bosboom, Dennis G.H.; Koopmanschap, Desiree H.J.L.M. [Radboud University Medical Center, Department of Radiology and Nuclear Medicine, Nijmegen (Netherlands); Nievelstein, Rutger A.J. [University Medical Center Utrecht, Department of Radiology, Utrecht (Netherlands); Nikkels, Peter G.J. [University Medical Center Utrecht, Department of Pathology, Utrecht (Netherlands); Rijn, Rick R. van [Academic Medical Center, Department of Radiology, Amsterdam (Netherlands)

    2015-04-01

    Postmortem radiology is a rapidly developing specialty that is increasingly used as an adjunct to or substitute for conventional autopsy. The goal is to find patterns of disease and possibly the cause of death. Postmortem CT images bring to light processes of decomposition most radiologists are unfamiliar with. These postmortem changes, such as the formation of gas and edema, should not be mistaken for pathological processes that occur in living persons. In this review we discuss the normal postmortem thoraco-abdominal changes and how these appear on CT images, as well as how to differentiate these findings from those of pathological processes. (orig.)

  12. Patterns of uterine enhancement with helical CT

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    Kaur, H.; Loyer, E.M.; Charnsangavej, C. [Department of Diagnostic Radiology, Box 57, The University of Texas, M.D. Anderson Cancer Center, 1515 Holcombe Blvd. Houston, TX 77030 (United States); Minami, M. [Department of Radiology, Faculty of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-Ku, Tokyo 113 (Japan)

    1998-10-01

    Objective: The purpose of this study was to evaluate the enhancement characteristics of the normal uterine body and cervix using dynamic contrast-enhanced helical CT. Methods: Thirty-eight women scheduled for pelvic CT for non-gynecologic malignancies underwent dynamic contrast-enhanced helical CT of the pelvis. Data acquisition was during the arterial phase (30-45 s after the start of injection), the parenchymal phase (90-120 s after the start of injection), and delayed phase (3-9 min after the start of injection). The images were evaluated by four radiologists for the pattern of myometrial and cervical enhancement. Correlation was made with the age and menstrual status of the patients. Results: In the uterine body, three types of enhancement were observed. Type 1 enhancement, seen in 16 patients (42%), was characterized by the visualization of a subendometrial zone of enhancement, 30-120 s after the start of injection. Eight of these patients also showed an enhancing zone in the outer myometrium. Both zones were transitory, and in all cases, the uterus became homogeneous in the delayed phase. This pattern was seen predominantly in premenopausal women with a mean age of 34 years. Type 2 enhancement, seen in 17 cases (45%), was defined by the absence of subendometrial enhancement in the early phase. Enhancement was either diffuse from the outset or originated in the outer myometrium. This pattern was seen nearly equally in premenopausal and postmenopausal women with a mean age of 40 years. Type 3 enhancement was seen in five postmenopausal patients (13%) with a mean age of 53 years and was characterized by faint diffuse enhancement. In the cervix, a zonal pattern of enhancement defining inner and outer stroma was seen in 23 patients (61%). Fifteen patients were premenopausal and eight were postmenopausal. Conclusion: In this study, we have shown a transitory zonal distribution of the contrast in the myometrium and cervix using dynamic contrast-enhanced helical CT

  13. Patterns of uterine enhancement with helical CT

    International Nuclear Information System (INIS)

    Kaur, H.; Loyer, E.M.; Charnsangavej, C.; Minami, M.

    1998-01-01

    Objective: The purpose of this study was to evaluate the enhancement characteristics of the normal uterine body and cervix using dynamic contrast-enhanced helical CT. Methods: Thirty-eight women scheduled for pelvic CT for non-gynecologic malignancies underwent dynamic contrast-enhanced helical CT of the pelvis. Data acquisition was during the arterial phase (30-45 s after the start of injection), the parenchymal phase (90-120 s after the start of injection), and delayed phase (3-9 min after the start of injection). The images were evaluated by four radiologists for the pattern of myometrial and cervical enhancement. Correlation was made with the age and menstrual status of the patients. Results: In the uterine body, three types of enhancement were observed. Type 1 enhancement, seen in 16 patients (42%), was characterized by the visualization of a subendometrial zone of enhancement, 30-120 s after the start of injection. Eight of these patients also showed an enhancing zone in the outer myometrium. Both zones were transitory, and in all cases, the uterus became homogeneous in the delayed phase. This pattern was seen predominantly in premenopausal women with a mean age of 34 years. Type 2 enhancement, seen in 17 cases (45%), was defined by the absence of subendometrial enhancement in the early phase. Enhancement was either diffuse from the outset or originated in the outer myometrium. This pattern was seen nearly equally in premenopausal and postmenopausal women with a mean age of 40 years. Type 3 enhancement was seen in five postmenopausal patients (13%) with a mean age of 53 years and was characterized by faint diffuse enhancement. In the cervix, a zonal pattern of enhancement defining inner and outer stroma was seen in 23 patients (61%). Fifteen patients were premenopausal and eight were postmenopausal. Conclusion: In this study, we have shown a transitory zonal distribution of the contrast in the myometrium and cervix using dynamic contrast-enhanced helical CT

  14. Dynamic helical CT mammography of breast cancer

    International Nuclear Information System (INIS)

    Yamamoto, Akira; Fukushima, Hitoshi; Okamura, Ryuji; Nakamura, Yoshiaki; Morimoto, Taisuke; Urata, Yoji; Mukaihara, Sumio; Hayakawa, Katsumi

    2006-01-01

    The purpose of this study was to determine whether dynamic helical computed tomography (CT)-mammography could assist in selecting the most appropriate surgical method in women with breast cancer. Preoperative contrast-enhanced helical CT scanning of the breast was performed on 133 female patients with suspicion of breast cancer at the same time as clinical, mammographic, and/or ultrasonographic examinations. The patients were scanned in the prone position with a specially designed CT-compatible device. A helical scan was made with rapid intravenous bolus injection (3 ml/s) of 100 ml of iodine contrast material. Three-dimensional maximum intensity projection (MIP) images were reconstructed, and CT findings were correlated with surgical and histopathological findings. Histopathological analysis revealed 84 malignant lesions and seven benign lesions. The sensitivity, specificity, and accuracy levels of the CT scanning were 94.6%, 58.6%, and 78.9%. Helical scanning alone revealed additional contralateral carcinomas in three of four patients and additional ipsilateral carcinomas in three of five patients. However, the technique gave false-positive readings in 24 patients. The preoperative CT-mammogram altered the surgical method in six patients. Dynamic helical CT-mammography in the prone position may be one of the choices of adjunct imaging in patients with suspected breast cancer scheduled for surgery. (author)

  15. CT appearances of abdominal tuberculosis

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    Lee, W.-K., E-mail: leewk33@hotmail.com [Department of Medical Imaging, St Vincent' s Hospital, University of Melbourne, Fitzroy, Victoria (Australia); Van Tonder, F.; Tartaglia, C.J.; Dagia, C. [Department of Medical Imaging, St Vincent' s Hospital, University of Melbourne, Fitzroy, Victoria (Australia); Cazzato, R.L. [Department of Radiology, Universita Campus Bio-Medico di Roma, Rome (Italy); Duddalwar, V.A. [Department of Radiology, Norris Comprehensive Cancer Center, University of Southern California, Los Angeles, California (United States); Chang, S.D. [Department of Medical Imaging, Vancouver General Hospital, University of British Columbia, British Columbia (Canada)

    2012-06-15

    The purpose of this article is to review and illustrate the spectrum of computed tomography (CT) appearances of abdominal tuberculosis. Tuberculosis can affect any organ or tissue in the abdomen, and can be mistaken for other inflammatory or neoplastic conditions. The most common sites of tuberculosis in the abdomen include lymph nodes, genitourinary tract, peritoneal cavity and gastrointestinal tract. The liver, spleen, biliary tract, pancreas and adrenals are rarely affected, but are more likely in HIV-seropositive patients and in miliary tuberculosis. This article should alert the radiologist to consider abdominal tuberculosis in the correct clinical setting to ensure timely diagnosis and enable appropriate treatment.

  16. CT appearances of abdominal tuberculosis

    International Nuclear Information System (INIS)

    Lee, W.-K.; Van Tonder, F.; Tartaglia, C.J.; Dagia, C.; Cazzato, R.L.; Duddalwar, V.A.; Chang, S.D.

    2012-01-01

    The purpose of this article is to review and illustrate the spectrum of computed tomography (CT) appearances of abdominal tuberculosis. Tuberculosis can affect any organ or tissue in the abdomen, and can be mistaken for other inflammatory or neoplastic conditions. The most common sites of tuberculosis in the abdomen include lymph nodes, genitourinary tract, peritoneal cavity and gastrointestinal tract. The liver, spleen, biliary tract, pancreas and adrenals are rarely affected, but are more likely in HIV-seropositive patients and in miliary tuberculosis. This article should alert the radiologist to consider abdominal tuberculosis in the correct clinical setting to ensure timely diagnosis and enable appropriate treatment.

  17. Helical CT of congenital ossicular anomalies

    International Nuclear Information System (INIS)

    Osada, Hisato; Machida, Kikuo; Honda, Norinari

    2001-01-01

    Since January 1996 to December 2000, 26 cases of congenital ossicular anomaly could be diagnosed with helical CT. All cases were unilateral. In 8 patients with malformation of the external ear, CT showed malleoincudal fixation (n=5), malleoincudal fixation and deformed incuts long process (n=1), deformed incus long process (n=1), and partial fusion of malleus neck and incus long process (n=1). In 18 patients with normal external ear, CT showed defect of the incus long process (n=5), defect of both the incus long process and stapes superstructure (n=8, 2 patients with congenital cholesteatoma, 1 with hypoplastic oval window), defect of the stapes superstructure (n=2, 1 patient with oval window absence), defect of the malleus manubrium (n=1), ossification of the stampede's tendon (n=1), and monopod stapes (n=1). Helical CT can evaluate the auditory ossicular chain in detail and is useful for diagnosing congenital ossicular anomaly. (author)

  18. Helical CT in acute lower gastrointestinal bleeding

    International Nuclear Information System (INIS)

    Ernst, Olivier; Leroy, Christophe; Sergent, Geraldine; Bulois, Philippe; Saint-Drenant, Sophie; Paris, Jean-Claude

    2003-01-01

    The purpose of this study was to assess the usefulness of helical CT in depicting the location of acute lower gastrointestinal bleeding. A three-phase helical CT of the abdomen was performed in 24 patients referred for acute lower gastrointestinal bleeding. The diagnosis of the bleeding site was established by CT when there was at least one of the following criteria: spontaneous hyperdensity of the peribowel fat; contrast enhancement of the bowel wall; vascular extravasation of the contrast medium; thickening of the bowel wall; polyp or tumor; or vascular dilation. Diverticula alone were not enough to locate the bleeding site. The results of CT were compared with the diagnosis obtained by colonoscopy, enteroscopy, or surgery. A definite diagnosis was made in 19 patients. The bleeding site was located in the small bowel in 5 patients and the colon in 14 patients. The CT correctly located 4 small bowel hemorrhages and 11 colonic hemorrhages. Diagnosis of the primary lesion responsible for the bleeding was made in 10 patients. Our results suggest that helical CT could be a good diagnostic tool in acute lower gastrointestinal bleeding to help the physician to diagnose the bleeding site. (orig.)

  19. Aortic non communicating dissections. A study with helical CT

    International Nuclear Information System (INIS)

    Midiri, M.; Strada, A.; Stabile Ianora, A.A.; Rotondo, A.; Angelelli, G.; D'Agostino, D.; De Luca Tupputi Schinosa, L.

    2000-01-01

    The evaluate the signs of aortic intramural hematoma with helical CT and the diagnostic role of this technique in patients with this condition. It was reviewed the CT findings of 396 patients submitted to emergency examinations for suspected aortic dissection from 1995 to 1999. Only 18 patients (6 women and 12 men) had CT signs of aortic intramural hematoma. Helical CT studies were carried out with the following parameters: slice thickness 10 mm, reconstruction index 10, feed 1.5 mm, conventional algorithm with minimum values of 130 kV and 125mA. All patients were examined with dynamic contrast-enhanced CT, before and after a power injection of 130 mL ionic contrast material. It was studied: hematoma localization and longitudinal extension; thickness and density of aortic wall; presence and location of intimal calcifications; integrity of intimal wall; hemo mediastinum and/or hemo thorax. Aortic wall thickening appeared as a high density crescent-shaped area at baseline CT and had low density on enhanced images in all patients. Thickening was eccentric in 14/18 patients and concentric in 4/18 only; it always exceeded 4 mm. It was found some intimal calcifications in 8 patients and hemo thorax and/or hemo mediastinum in 9 patients. A patient with type A hematoma died of cardiac tamponade a few hours after CT diagnosis. Six patients (5 type B and 1 type A) underwent anti-hypertensive treatment and radiological follow-up. Eleven patients (6 type A and 5 type B) underwent prosthesis replacement and 5 of them (3 type A and 2 type B) died of postoperative complications. In the 5 type B patients surgery was performed because of treatment-resistant pain and of the onset of ischemic complications to abdominal organs caused by involvement of the main collateral branches of the aorta. One patient with type A hematoma was submitted to drug treatment because it was judged unresectable. Intramural hematoma of the aorta is a distinct pathological entity, which should not be

  20. Struma ovarii. MR and CT appearance

    International Nuclear Information System (INIS)

    Joja, Ikuo; Mitsumori, Akihito; Hiraki, Yoshio; Kudo, Takafumi; Nakagawa, Tomio; Asakawa, Toru; Ando, Masaaki; Akamatsu, Nobuo.

    1997-01-01

    The purpose of this study was to examine the appearance of struma ovarii on MR and CT images. All 13 patients showed both cystic and solid components with a multilobulated surface and thickened septa. Various signal intensities were seen on both T1WI and T2WI. The cystic component, which showed low signal intensity on T2WI, showed high density on CT images. The characteristic MR and CT appearance of struma ovarii appears to be that of multicystic tumor indicating the presence of viscid materials containing iodine. (author)

  1. The CT appearance of intraoral chewing gum

    International Nuclear Information System (INIS)

    Towbin, Alexander J.

    2008-01-01

    When imaged, intraoral chewing gum has the potential to be misdiagnosed. Chewing gum has a characteristic appearance on CT: it is ovoid in shape, hyperdense, and has small internal locules of air. Reports have described the appearance of gum on radiographs and abdominal CT images; however, no reports could be found detailing its appearance within the mouth. This report describes the appearance of intraoral chewing gum as well as the properties of the gum that lead to this appearance. Because of the potential for misdiagnosis, screening for intraoral foreign bodies should be considered prior to imaging. (orig.)

  2. The CT appearance of intraoral chewing gum

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    Towbin, Alexander J. [Cincinnati Children' s Hospital Medical Center, Department of Radiology, Cincinnati, OH (United States)

    2008-12-15

    When imaged, intraoral chewing gum has the potential to be misdiagnosed. Chewing gum has a characteristic appearance on CT: it is ovoid in shape, hyperdense, and has small internal locules of air. Reports have described the appearance of gum on radiographs and abdominal CT images; however, no reports could be found detailing its appearance within the mouth. This report describes the appearance of intraoral chewing gum as well as the properties of the gum that lead to this appearance. Because of the potential for misdiagnosis, screening for intraoral foreign bodies should be considered prior to imaging. (orig.)

  3. CT appearance and features of tubal pregnancy

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    Xiaohong, Wang; Hong, Shan; Zaibo, Jiang; Xinghe, Deng; Xiaochun, Meng; Bingbing, Ye; Mingyue, Luo; Yunya, Lin [Sun Yat-sen Univ., Guangzhou (China). The Third Univ. Hospital, Dept. of Radiology

    2004-06-01

    Objective: To investigate the CT appearance and features of tubal pregnancy. Methods: Precontrast and postcontrast CT scans were employed in 38 patients who were clinically and ultrasonographically suspected of tubal pregnancy. 34 of them were verified as tubal pregnancy through operative pathology. Results: 1. The direct CT imaging feature was the whole pregnancies sac (4/34, 11.8%) or half-baked pregnancies sac (14/34, 41.2%); 2. The indirect CT imaging features were: (1) abnormal density image, which could be enhanced, in a cystic mass around adnexal area (8/34, 23.5%); (2) mix density mass around adnexal area, which was mainly solid and had mild to moderate inhomogeneous enhancement (19/34, 55.9%); (3) large area irregular shadow with high density were found beside the uterus, with no enhancement (3/34, 8.8%). (4) bloody density in uterus-rectum-fossa (23/34, 67.6%). 3. The CT imaging features of tubal pregnancy was classified as: (1) Pregnant sac type (4/34, 11.8%); (2) Cystic (8/34, 23.5%); (3) Massive type (17/34, 50%); (4) Chronic mass type (2/34, 5.9%); (5) Bleeding type (3/34, 8.8%). 4. The CT imaging appearance of tubal pregnancy related with the pregnancy location; 5. The CT imaging appearance of tubal pregnancy related with the clinical significant. Conclusion: The CT imaging appearance of tubal pregnancy has some features, which can help in the diagnosis or differential diagnosis of the pelvis masses. CT scan is an effective supplementary attempt to the clinically and ultrasonographically suspected tubal pregnancy patients.

  4. CT appearance and features of tubal pregnancy

    International Nuclear Information System (INIS)

    Wang Xiaohong; Shan Hong; Jiang Zaibo; Deng Xinghe; Meng Xiaochun; Ye Bingbing; Luo Mingyue; Lin Yunya

    2004-01-01

    Objective: To investigate the CT appearance and features of tubal pregnancy. Methods: Precontrast and postcontrast CT scans were employed in 38 patients who were clinically and ultrasonographically suspected of tubal pregnancy. 34 of them were verified as tubal pregnancy through operative pathology. Results: 1. The direct CT imaging feature was the whole pregnancies sac (4/34, 11.8%) or half-baked pregnancies sac (14/34, 41.2%); 2. The indirect CT imaging features were: (1) abnormal density image, which could be enhanced, in a cystic mass around adnexal area (8/34, 23.5%); (2) mix density mass around adnexal area, which was mainly solid and had mild to moderate inhomogeneous enhancement (19/34, 55.9%); (3) large area irregular shadow with high density were found beside the uterus, with no enhancement (3/34, 8.8%). (4) bloody density in uterus-rectum-fossa (23/34, 67.6%). 3. The CT imaging features of tubal pregnancy was classified as: (1) Pregnant sac type (4/34, 11.8%); (2) Cystic (8/34, 23.5%); (3) Massive type (17/34, 50%); (4) Chronic mass type (2/34, 5.9%); (5) Bleeding type (3/34, 8.8%). 4. The CT imaging appearance of tubal pregnancy related with the pregnancy location; 5. The CT imaging appearance of tubal pregnancy related with the clinical significant. Conclusion: The CT imaging appearance of tubal pregnancy has some features, which can help in the diagnosis or differential diagnosis of the pelvis masses. CT scan is an effective supplementary attempt to the clinically and ultrasonographically suspected tubal pregnancy patients

  5. Rare variations in renal anatomy and blood supply: CT appearances and embryological background. A pictorial essay

    International Nuclear Information System (INIS)

    Cocheteux, B.; Gaxotte, V.; Beregi, J.P.; Mounier-Vehier, C.; McFadden, E.P.; Francke, J.P.

    2001-01-01

    Helical CT angiography is increasingly used for the evaluation of the kidneys and the renal vessels. Knowledge of the potential variants in renal and renal vascular anatomy and of their appearances on helical CT are thus indispensable for radiologists who perform and interpret such examinations. We report six cases of anatomic variants that we encountered in our tertiary referral centre over the past 5 years, during which time we have performed 4850 helical CT angiograms, including 1432 renal artery examinations. These represent rarer anomalies in renal vascularization, most of which were associated with renal malformations (horseshoe kidney with or without cortical torsion, renal malrotation, single kidney, and thoracic origin of a renal artery). We present the helical CT findings and discuss the possible embryological mechanisms and the practical implications of these abnormalities for the radiologist. (orig.)

  6. Rare variations in renal anatomy and blood supply: CT appearances and embryological background. A pictorial essay

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    Cocheteux, B.; Gaxotte, V.; Beregi, J.P. [Dept. of Vascular Radiology, Hopital Cardiologique, CHRU de Lille (France); Mounier-Vehier, C. [Service d' Hypertension Arterielle et Medecine Interne, Hopital Cardiologique, CHRU de Lille (France); McFadden, E.P. [Service de Cardiologie B, Hopital Cardiologique, CHRU de Lille (France); Francke, J.P. [Lab. d' Anatomie, Faculte de Medecine, Lille (France)

    2001-05-01

    Helical CT angiography is increasingly used for the evaluation of the kidneys and the renal vessels. Knowledge of the potential variants in renal and renal vascular anatomy and of their appearances on helical CT are thus indispensable for radiologists who perform and interpret such examinations. We report six cases of anatomic variants that we encountered in our tertiary referral centre over the past 5 years, during which time we have performed 4850 helical CT angiograms, including 1432 renal artery examinations. These represent rarer anomalies in renal vascularization, most of which were associated with renal malformations (horseshoe kidney with or without cortical torsion, renal malrotation, single kidney, and thoracic origin of a renal artery). We present the helical CT findings and discuss the possible embryological mechanisms and the practical implications of these abnormalities for the radiologist. (orig.)

  7. CT appearance of amiodarone-induced pneumonitis

    International Nuclear Information System (INIS)

    Nicholson, A.A.; Hayward, C.

    1989-01-01

    Basal peripheral pleuroparenchymal opacities are described on CT of early cryptogenic fibrosing alveolitis, asbestosis and bleomycin pneumonitis. These diseases may be caused by free radical effects on phospholipid metabolism causing cell wall damage. Amiodarone hydrochloride alters phospholipid synthesis metabolically. Amiodarone pneumonitis might be expected to show similar CT appearances. Sixteen patients who have developed new respiratory symptoms while taking amiodarone have been scanned prone and supine and at inspiration and expiration by means of a scanner with 2-mm sections at 1-cm intervals. All have been previously healthy nonsmokers with no relevant occupational history. Previous chest radiographs have been normal. Results are presented

  8. CT appearances of emphysema and clinical application

    International Nuclear Information System (INIS)

    Wang Xinlian; Ma Daqing; Chen Budong; He Wen; Guan Yansheng; Zhang Yansong; Tang Hongqu; Wang Zhenguang

    2006-01-01

    Objective: To investigate CT appearances of different types of emphysema and to determine the clinic value for differential diagnosis. Methods: Twenty-three specimens with emphysema selected from 33 autopsy specimens were included in this study. All specimens were inflated and fixed by Heitzman's method, then examined by spiral CT scan. The CT appearances of different types of emphysema in every specimen were analyzed. After the specimens were cut into 10 mm thickness slices, the CT- pathologic correlation was done. Fifteen clinical cases confirmed by pathology or clinical process were all performed spiral CT scan and analyzed, including emphysema-accompanying pneumonia 11 cases, emphysema-accompanying nodule 4 cases. Result: Centriacinar emphysema (CAE)can be seen in 21 of 23 specimens, pancinar emphysema(PAE) can be seen in 5 of 23 specimens, all coexisting with CAE. Distal acinar emphysema(DAE) can be seen in 19 of 23 specimens, irregular emphysema can be seen in 3 of 23 specimens. In all specimens, emphysema can be seen in bilateral lung fields, distributing similarly. Seventeen of 23 eases (17/23) showed no less than two types of emphysema. Fourteen cases of emphysema- accompanying pneumonia (clinic: 11 cases, specimen: 3 cases) showed 'pseudocavity' or 'pseudohoneycombing' (emphysema lesion that had not been filled in the consolidation). Four eases of emphysema-accompanying nodule showed 'pseudopleuralhollow' (wall of DAE or bulla connecting with nodule). Conclusion: The CT manifestations of emphysema, the characteristics of distribution and multi- type of emphysema coexisting can help differentiate cystic air space diseases. The characteristics of complications of emphysema, the 'pseudocavity', 'pseudohoneycombing' and 'pseudopleuralhollow', may be help for differential diagnosis. (authors)

  9. Gynecological applications of helical CT using SmartPrep

    Energy Technology Data Exchange (ETDEWEB)

    Sakurada, Akira; Kakizaki, Dai; Abe, Kimihiko [Tokyo Medical Coll. (Japan)

    1999-11-01

    SmartPrep is software program for scanning a given region of interest (ROI) at optimal contrast density. An operator can arbitrarily define ROI and preset the CT value at which scanning should be started. After the injection of a contrast medium, system conducts continuous monitoring of the ROI and the operator starts helical scanning of the planned region when the present CT value has been reached. In comparison with conventional helical CT that requires a period of time from the beginning of contrast medium injection to the beginning of scanning, SmartPrep minimizes personal error and better depicts the artery-predominant phase under optimal conditions. In this study we examine the usefulness of contrast-enhanced helical CT using SmartPrep in the evaluation of gynecological disease. When the contrast medium was injected into the dorsal vein of the hand at a rate of 3 ml/sec, strong staining of pelvic arteries was observed in the CT images started at 17 to 23 sec after injection. The early-phase helical CT obtained under these conditions provided good depiction of lesions in cases of placenta accreta and invasive mole, as well as clear demonstration of tumor angiogenesis and evaluation of laterality in cases of cervical cancer. Comparison of the early and delayed phase also facilitated easier evaluation of lymph nodes than conventional comparison of simple and contrast-enhanced CT. The results thus suggest the usefulness of contrast-enhanced helical CT using SmartPrep in gynecology. (author)

  10. Postoperative CT appearance in chronic subdural hematomas

    Energy Technology Data Exchange (ETDEWEB)

    Kaneko, Takaaki; Nishikawa, Michio; Handa, Hajime; Iwaki, Kazuo; Sawai, Teruaki; Munaka, Masahiro

    1988-05-01

    Postoperative CT appearances in 65 cases of chronic subdural hematomas were evaluated in terms of patient's age, preoperative neurological symptoms and CT findings, final outcomes, and so on. All of the cases were treated with trepanation and irrigation. CT appearances were divided into four different types as follows; Type Ia: No abnormal findings in the subdural sapce, Type Ib: The same as above except for a linear high density suggestive of thickened outer membrane, Type II: Persistence subdural fluid collection and widened cortical sulci which indicate underlining brain atrophy, Type III: Remaining hematoma and/or density changes during follow-up period. Although the mean age of the patients in type Ib was higher than those in type Ia and reexpansion of the brain appear to delay in type Ib and preoperative CT in type Ib tended to show mixed density, final outcome in both groups were excellent. Characteristics in type II were that most of cases were in the eighth decade, preceding head injury was unclear, preoperative psychiatric symptoms and disturbance of consciousness were common and postoperative improvement of the symptoms was not satisfactory compared to other types. Aged patients as in type Ib and type II and thick hematomas of over 2 cm depth with mixed or high density tended to show type III postoperatively. All of the nine patients who required reoperation were included in this type. The present study indicates that thick hematomas with sizable mass effect and mixed or high density in the aged must be carefully treated, such as with placement of the subdural drainage or keeping the patient in the Trendelenburg position, to facilitate postoperative reexpansion of the brain.

  11. Helical CT in evaluation of the bronchial tree

    International Nuclear Information System (INIS)

    Perhomaa, M.; Laehde, S.; Rossi, O.; Suramo, I.

    1997-01-01

    Purpose: To establish a protocol for and to assess the value of helical CT in the imaging of the bronchial tree. Material and Methods: Noncontrast helical CT was performed in 30 patients undergoing fiberoptic bronchoscopy for different reasons. Different protocols were compared; they included overlapping 10 mm, 5 mm, or 3 mm slices and non-tilted, cephalad or caudal tilted images. Ordinary cross-sectional and multiplanar 2D reformats were applied for visualization of the bronchial branches. The effect of increasing the helical pitch was tested in one patient. Results: A total of 92.1-100% of the segmental bronchi present in the helical acquisitions were identified by the different protocols. The collimation had no significant impact on the identification of the bronchial branches, but utilization of 3-mm overlapping slices made it easier to distinguish the nearby branches and provided better longitudinal visualization of the bronchi in 2D reformats. The tilted scans illustrated the disadvantage of not covering all segmental bronchi in one breath-hold. An increase of the pitch from 1 to 1.5 did not cause noticeable blurring of the images. CT and bronchoscopic findings correlated well in the area accessible to bronchoscopy, but CT detected 5 additional pathological lesions (including 2 cancers) in the peripheral lung. Conclusion: Helical CT supplemented with bronchography-like 2D reformats provides an effective method complementary to bronchoscopy in the examination of the bronchial tree. (orig.)

  12. Elastofibroma Dorsi: CT and MRI appearance

    International Nuclear Information System (INIS)

    Bonini, Claudio J.; Costamagna, Cecilia L.; Staffieri, Roberto; Villavicencio, Roberto L.; Milatich, Viviana

    2002-01-01

    Objective: To describe the findings of fibroelastomas by CT and MR imaging. Material and Methods: We studied 7 female patients, aged 60 to 75 years. All patients presented a unilateral soft tissue mass in the periscapular region (4 left sided and 3 right sided); one patient developed a contralateral lesion one year later. Four patients had pain and underwent surgical excision of the lesions; 2 patients underwent percutaneous biopsy and the last patient is under clinical and imaging follow-up. Results: The lesions had a tomographic density to muscle, but with the presence of hypodense bands corresponding to adipose tissue. After the administration of IV contrast (5 cases) density remained similar to that of muscle. By MR, in the T1 sequence, the lesions were isointense to muscle and had hyperintense linear areas corresponding to adipose tissue bands. In the FSE T2 sequences, the lesions appeared mildly hyperintense. After the administration of IV gadolinium, the T1 sequence with fat suppression showed marked enhancement of the tumors. There was no involvement of neighboring bony or muscle structures. Conclusion: CT and MRI are useful methods for the detection of periscapular fibroelastomas. (author)

  13. Helical CT of traumatic injuries of the thoracic aorta

    International Nuclear Information System (INIS)

    Mengozzi, E.; Burzi, M.; Miceli, M.; Lipparini, M.; Sartoni Galloni, S.

    2000-01-01

    Acute thoracic aortic injuries account for up to 10-20% of fatalities in high-speed deceleration road accidents and have an estimated immediate fatality rate of 80-90%. Untreated survivors to acute trauma (10-20%) have a dismal prognosis: 30% of them die within 6 hours, 40-50% die within 24 hours, and 90% within 4 months. It was investigated the diagnostic accuracy of Helical Computed Tomography (Helical CT) in acute traumatic injuries of the thoracic aorta, and the role of this technique in the diagnostic management of trauma patients with a strong suspicion of aortic rupture. It was compared retrospectively the chest Helical CT findings of 256 trauma patients examined June 1995 through August 1999. Chest Helical CT examinations were performed according to trauma score, to associated traumatic lesions and to plain chest radiographic findings. All the examinations were performed with no intravenous contrast agent administration and the pitch 2 technique. After a previous baseline study, contrast-enhanced scans were acquired with pitch 1 in 87 patients. Helical CT showed aortic lesions in 9 of 256 patients examined. In all the 9 cases it was found a mediastinal hematoma and all of them had positive plain chest radiographic findings of mediastinal enlargement. Moreover, in 6 cases aortic knob blurring was also evident on plain chest film and in 5 cases depressed left mainstem bronchus and trachea deviation rightwards were observed. All aortic lesions were identified on axial scans and located at the isthmus of level. Aortic rupture was always depicted as pseudo diverticulum of the proximal descending tract and intimal flap. It was also found that periaortic hematoma in 6 cases and intramural hematoma in 1 case. There were non false positive results in the series: 7 patients with Helical CT diagnosis of aortic rupture were submitted to conventional aortography that confirmed both type and extension of the lesions as detected by Helical CT, and all findings were

  14. Low dose coronary CT angiography with 256-slice helical CT

    International Nuclear Information System (INIS)

    Zhang Xiaodong; Tang Binghang; Li Fangyun

    2011-01-01

    of 573) in B, 96.1% (548 of 570) in C, and 85.7% (505/589) in D, with no significant difference for A vs C (Z= -1.351, P>0.05) and with significant differences for B vs D (Z=-2.236, P<0.05). Linear correlation analysis indicated a significant degradation of image quality with the increase of heart rate using SAS mode (Spearman correlation, r=0.577, P<0.01). ROC analysis established an upper HR threshold of 78 bpm for obtaining diagnostic image quality using SAS mode (AUC = 0.827, P<0.05). The average radiation dose in group A [(2.6±0.5) mSv] reduced 75% comparing with that in group C [(10.6±2.3) mSv], and the average radiation dose in group B [(4.0±0.7) mSv] reduced 69% comparing with that in group D [(13.0±1.4) mSv]. Conclusion: Using SAS mode to perform low-dose CCTA with 256-slice helical CT could keep the image quality and reduce radiation dose significantly. Our preliminary experience suggests a good promise of this technique which could be applied to a wider group of patients such as with higher heart rates. (authors)

  15. Gaucher disease of the liver: CT appearance

    International Nuclear Information System (INIS)

    Glass, R.B.J.; Poznanski, A.K.; Young, S.; Urban, M.A.

    1987-01-01

    We present a child with Gaucher disease with hepatic involvement that caused portal hypertension. Computerized tomography (CT) showed distortion of liver parenchyma and central necrosis of the liver. (orig.)

  16. A rigid motion correction method for helical computed tomography (CT)

    International Nuclear Information System (INIS)

    Kim, J-H; Kyme, A; Fulton, R; Nuyts, J; Kuncic, Z

    2015-01-01

    We propose a method to compensate for six degree-of-freedom rigid motion in helical CT of the head. The method is demonstrated in simulations and in helical scans performed on a 16-slice CT scanner. Scans of a Hoffman brain phantom were acquired while an optical motion tracking system recorded the motion of the bed and the phantom. Motion correction was performed by restoring projection consistency using data from the motion tracking system, and reconstructing with an iterative fully 3D algorithm. Motion correction accuracy was evaluated by comparing reconstructed images with a stationary reference scan. We also investigated the effects on accuracy of tracker sampling rate, measurement jitter, interpolation of tracker measurements, and the synchronization of motion data and CT projections. After optimization of these aspects, motion corrected images corresponded remarkably closely to images of the stationary phantom with correlation and similarity coefficients both above 0.9. We performed a simulation study using volunteer head motion and found similarly that our method is capable of compensating effectively for realistic human head movements. To the best of our knowledge, this is the first practical demonstration of generalized rigid motion correction in helical CT. Its clinical value, which we have yet to explore, may be significant. For example it could reduce the necessity for repeat scans and resource-intensive anesthetic and sedation procedures in patient groups prone to motion, such as young children. It is not only applicable to dedicated CT imaging, but also to hybrid PET/CT and SPECT/CT, where it could also ensure an accurate CT image for lesion localization and attenuation correction of the functional image data. (paper)

  17. An experimental study for qualitatively diagnosing stapes lesions by helical 3-dimensional CT

    International Nuclear Information System (INIS)

    Kawaue, Akifumi; Kuki, Kiyonori; Yamanaka, Noboru; Nishimura, Michihiko

    2001-01-01

    To evaluate qualitative diagnosis of stapes lesions by 3-dimensional computed tomography (3D-CT) combined with superselective image processing (3D-SS) of stapes, we studied helical 3D-CT on a phantom model of the temporal bone. Two stapes models were used-1 made from the bone filler, Celatite, consistent in bone density but changing in cross sectional area, and the other made from an apacerum rod used in quantitative computed tomography (QCT), consistent in cross sectional area but changing in bone density. These stapes models were put into a skull phantom and analyzed by helical 3D-CT. The influence of the tympanic cavity conditions on CT images of stapes was evaluated by filling the phantom model with Vaseline following 3D selective reconstruction. In all stapes models, lowering the lower CT window width threshold resulted in an enlarged cross-sectional area of the model. The higher the bone density, the lower the increase in cross-sectional area in the image. The stapes model with lower density had greater influence on the imaging by tympanic cavity conditions and was likely to be misdiagnosed as showing higher bone density. Based on the experimental study, 3D-SS by helical 3D-CT appears to be a useful measure for qualitatively diagnosing stapes lesions. (author)

  18. Multiphasic helical CT of hepatocellular carcinoma. Evaluation after chemo embolization

    International Nuclear Information System (INIS)

    Catalano, O.; Esposito, M.; Sandomenico, F.; Siani, A.; Nunziata, A.

    2000-01-01

    The main purpose of this work is to report the personal experience with addition of contrast-enhanced multiphase helical CT to unenhanced CT (Lipiodol CT) in the evaluation of patients with hepatocellular carcinoma treated with chemoembolization and to analyze the present role of oily agent CT. It has been retrospectively reviewed the examinations of 42 consecutive patients submitted to globla chemoembolization over a 2-year period. CT was performed 18-30 days after the treatment. The Lipiodol CT study was carried out with volume acquisitions. It has been considered as nodules all well-defined areas with dense oily agent uptake; uptake itself was classified as: 0=absent, I=lower tha 10% of the tumor volume; II=lower than 50%, III=50%, IV=homogeneous. Contrast-enhanced helical CT was performed with the 2-phase technique in 28 patients and with the 3-phase technique in 14; it has been considered as nodules all well-defined and relatively homogeneous areas with hyperattenuation in the arterial phase and hypo-isoattenuation in the portal and/or delayed phase, or with hypo-isoattenuation in the arterial phase and in the portal and/or delayed phase. Lipiodol CT permitted to recognize 65 nodules (1-5/patient, mean 1.5), namely 15 grade I, 21 grade II, 20 grade III and 9 grade IV. Multiphase CT identified 6 additional nodules in 5 patients, 5 hypervascular and 1 hypovascular, and better assessed the correct morphology and volume of grade I nodules. Only 4 of 6 nodules missed on Lipiodol CT showed oily agent uptake after a new chemoembolization session. Moreover after retreatment, carried out in 6 of 9 patients with grade I uptake (11 nodules in all), it has been found persistence of the grade I pattern in 5 nodules, grade II in 5, and grade III in 1. Lipiodol CT may miss liver nodules and underestimate the volume of nodules with poor uptake. Though Lipiodol CT should still be considered slightly more sensitive than multiphase CT, in the general opinion this technique has

  19. Helical CT scan for emergent patients with cerebrovascular diseases

    International Nuclear Information System (INIS)

    Matsumoto, Masato; Sato, Naoki; Nakano, Masayuki; Watanabe, Youichi; Kodama, Namio

    1995-01-01

    We studied 44 emergent patients with cerebrovascular diseases (18 cases of subarachnoid hemorrhage, 15 of occlusive lesions, 7 of intracerebral hematoma and 4 of suspected subarachnoid hemorrhage) using helical CT scan. The helical CT scan was performed with contrast medium at a rate of 3 ml/sec with a delay of 20 sec, and was carried out before conventional angiography. The reconstruction time of 3D-CTA was within 10 min. We were able to obtain findings for the lesion on 3D-CTA before those on conventional angiography. The 3D-CTA yielded excellent images of the vascular structures and anatomical relationships of the aneurysm, its neck and parent artery, and surrounding arteries. However, it proved difficult to visualize vessels of less than 1 mm in diameter, especially the perforating arteries. In occlusive diseases, the degree of stenosis depended on the changes in CT number threshold: at present, evaluations of the lesions should be made by conventional angiography. 3D-CTA using helical CT scan can thus be applied for emergent patients with cerebrovascular diseases. Surgical simulation images of 3D-CTA were especially useful at the time of operation. (author)

  20. Helical CT scan for emergent patients with cerebrovascular diseases

    Energy Technology Data Exchange (ETDEWEB)

    Matsumoto, Masato; Sato, Naoki; Nakano, Masayuki; Watanabe, Youichi; Kodama, Namio [Fukushima Medical Coll. (Japan)

    1995-08-01

    We studied 44 emergent patients with cerebrovascular diseases (18 cases of subarachnoid hemorrhage, 15 of occlusive lesions, 7 of intracerebral hematoma and 4 of suspected subarachnoid hemorrhage) using helical CT scan. The helical CT scan was performed with contrast medium at a rate of 3 ml/sec with a delay of 20 sec, and was carried out before conventional angiography. The reconstruction time of 3D-CTA was within 10 min. We were able to obtain findings for the lesion on 3D-CTA before those on conventional angiography. The 3D-CTA yielded excellent images of the vascular structures and anatomical relationships of the aneurysm, its neck and parent artery, and surrounding arteries. However, it proved difficult to visualize vessels of less than 1 mm in diameter, especially the perforating arteries. In occlusive diseases, the degree of stenosis depended on the changes in CT number threshold: at present, evaluations of the lesions should be made by conventional angiography. 3D-CTA using helical CT scan can thus be applied for emergent patients with cerebrovascular diseases. Surgical simulation images of 3D-CTA were especially useful at the time of operation. (author).

  1. New reconstruction algorithm in helical-volume CT

    International Nuclear Information System (INIS)

    Toki, Y.; Rifu, T.; Aradate, H.; Hirao, Y.; Ohyama, N.

    1990-01-01

    This paper reports on helical scanning that is an application of continuous scanning CT to acquire volume data in a short time for three-dimensional study. In a helical scan, the patient couch sustains movement during continuous-rotation scanning and then the acquired data is processed to synthesize a projection data set of vertical section by interpolation. But the synthesized section is not thin enough; also, the image may have artifacts caused by couch movement. A new reconstruction algorithm that helps resolve such problems has been developed and compared with the ordinary algorithm. The authors constructed a helical scan system based on TCT-900S, which can perform 1-second rotation continuously for 30 seconds. The authors measured section thickness using both algorithms on an AAPM phantom, and we also compared degree of artifacts on clinical data

  2. Colonic metastasis from renal cell carcinoma: helical-CT demonstration

    International Nuclear Information System (INIS)

    Diaz-Candamio, M.J.; Pombo, S.; Pombo, F.

    2000-01-01

    Clinically evident colonic metastasis from renal cell carcinoma (RCC) is rare. In the present study a hypervascular sigmoid mass was demonstrated on arterial-phase helical CT using a water enema in a patient who had suffered left nephrectomy 8 years previously for RCC. The intense and early enhancement of the lesion suggested the possibility of a solitary colonic metastasis from RCC, a diagnosis which was pathologically confirmed. (orig.)

  3. Spatial variation of the section sensitivity profile in helical CT

    International Nuclear Information System (INIS)

    Katsuta, Shoichi; Hanai, Kouzou; Kunii, Takeo; Kimura, Haruki; Imabayashi, Wataru; Muramatsu, Yoshihisa

    1999-01-01

    The section sensitivity profile (SSP) is adequate to express the properties of helical CT images. Although SSP measurement has been performed only at the center of the imaging field, we applied it to off-center positions using a metal bead and controlled tracking technique. The experimental results indicated that SSP curves vary in the imaging field according to the relative position of the x-ray focus. The results were in agreement with computer simulations. (author)

  4. Uncommon locations of hydatid disease: CT appearances

    International Nuclear Information System (INIS)

    Gossios, K.J.; Kontoyiannis, D.S.; Dascalogiannaki, M.; Gourtsoyiannis, N.C.

    1997-01-01

    Hydatid disease (HD), already known by Hippocrates, is prevalent and widespread in most sheep-raising countries in Asia, Australia, South America, Near East, and southern Europe. The disease is most commonly due to Echinococcus granulosus and may occur in any organ or tissue. The location is mostly hepatic (75%) and pulmonary (15%), and only 10% occur in the rest of the body. Imaging modalities such as US, CT, and MR imaging are helpful in diagnosing the disease. The reliability of each method depends on the cyst's location in the body. The purpose of this essay is to illustrate the use of CT in depicting some unusual locations of HD besides the liver and lung. (orig.). With 18 figs

  5. Uncommon locations of hydatid disease: CT appearances

    Energy Technology Data Exchange (ETDEWEB)

    Gossios, K.J.; Kontoyiannis, D.S. [Department of Radiology, General Hospital of Ioannina, GR-450 01 Ioannina (Greece); Dascalogiannaki, M.; Gourtsoyiannis, N.C. [Department of Radiology, University of Crete Medical School, GR-711 10 Iraklion (Greece)

    1997-10-01

    Hydatid disease (HD), already known by Hippocrates, is prevalent and widespread in most sheep-raising countries in Asia, Australia, South America, Near East, and southern Europe. The disease is most commonly due to Echinococcus granulosus and may occur in any organ or tissue. The location is mostly hepatic (75%) and pulmonary (15%), and only 10% occur in the rest of the body. Imaging modalities such as US, CT, and MR imaging are helpful in diagnosing the disease. The reliability of each method depends on the cyst`s location in the body. The purpose of this essay is to illustrate the use of CT in depicting some unusual locations of HD besides the liver and lung. (orig.). With 18 figs.

  6. Unenhanced helical CT in the investigation of acute flank pain

    International Nuclear Information System (INIS)

    Colistro, Robert; Torreggiani, William C.; Lyburn, Iain D.; Harris, Alison C.; Al-Nakshabandi, Nizar A.; Nicolaou, Savvas; Munk, Peter L.

    2002-01-01

    Unenhanced helical CT has emerged as the imaging technique of choice for the investigation of patients presenting with acute flank pain and suspected nephroureteric stone disease. There are several signs identifiable on unenhanced CT that support a diagnosis of stone disease. However, there are many pitfalls, that may confound a correct diagnosis. Some of the common pitfalls, together with methods to avoid such occurrences, will be discussed. A review of some of the common alternative diagnoses that may mimic the symptoms of nephroureteric stone disease is illustrated. Colistro, R. et al (2002)

  7. New approach to lung cancer screening with helical volume CT

    International Nuclear Information System (INIS)

    Midorikawa, S.; Hashimoto, N.; Katakura, T.; Suzuki, K.

    1990-01-01

    This paper evaluates the relationship between reducing radiation dose to the patient and maintaining the clinical quality of the chest image in lung cancer screening by helical-volume CT (HVCT). The authors evaluated the changing relationship between radiation dose and clinical quality after changing the HVCY scanning conditions (such as stroke of patient transport and section thickness) as well as adding copper filters of various thickness and using high-voltage x-ray examination to complement CT examinations. The authors were able to reduce radiation dose by changing the HVCT scanning conditions (eg, stroke of 20 mm/sec, with a section thickness of 10 mm)

  8. Dual phase helical CT: diagnosis value for early pancreatic carcinoma

    International Nuclear Information System (INIS)

    Shen Bingqi; Zhang Ling; Zheng Keguo; Xu Dasheng

    2006-01-01

    Objective: To study dual-phase helical CT for the evaluation of early pancreatic cacinoma. Methods: Dual-phase helical CT was performed on 21 patients with early pancreatic carcinoma. In the enhanced imaging the contrast material was intravenously injected in a dose of 1.5 ml/kg at a rate of 3 ml/s. The image acquisition of the lesion in pancreatic phase (PP) and portal venous phase (PVP) were started at 35 seconds and 65 seconds after the start of the injection respectively. The enhancement of normal pancreas and tumor during the two phases was observed and compared. All data were statistically analyzed. Results: Tumor-pancreas contrast was significantly greater in PP (45.16±113.23) HU than in PVP (23.15±12.44) HU (t=2.13, P<0.01). Conclusion: Dual-phase helical CT scan for pancreas, including the imaging of the pancreatic and portal , venous phase, can be applied as an optimal selection. It can delineate early pancreatic carcinoma clearly and provide more information for the diagnosis of the lesion. The tumor-pancreas contrast was much higher' in PP than in PVP. (authors)

  9. CT appearance of menetrier's disease (a report of 4 cases)

    International Nuclear Information System (INIS)

    Peng Weijun; Zhang Pei; Zhou Kangrong; Chen Huiming

    2000-01-01

    Objective: To define the CT imaging characteristic of menetrier's disease. Methods: Four patients with proved Menetrier's disease were retrospectively studied by means of CT performed with the water as oral contrast, hypotonic agent and dynamic or spiral CT technique. Results: All cases showed that the enlarged rugae were seen projecting into the gastric lumen, but the gastric wall was otherwise normal. CT detected all lesions and made a confirmed diagnosis before pathology biopsy. Conclusion: The primary result revealed that the CT appearance of Menetrier's disease was quite characteristic, CT is a very valuable tool for the diagnosis of Menetrier's disease

  10. Cerebral CT appearances of toxic encephalopathy of tetramine

    International Nuclear Information System (INIS)

    Zheng Wenlong; Wu Aiqin; Xu Chongyong; Ying Binyu; Hong Ruizhen

    2003-01-01

    Objective: To investigate the cerebral CT appearances of toxic encephalopathy of tetramine and improve the recognition on this disease. Methods: Four cases of toxic encephalopathy of tetramine were collected and their cerebral CT appearances were retrospectively analyzed. Results: Cerebral CT appearances in acute phase (within 8 days): (1) cerebral edema in different degree. CT abnormalities consisted of cortical hypodensities and complete loss of gray-white matter differentiation. The CT value were in 11-13 HU, and to be watery density in serious case, (2) subarachnoid hemorrhage. It demonstrated the signs of poisoning hypoxic ischemic encephalopathy in chronic phase. Conclusion: The cerebral CT appearances of toxic encephalopathy of tetramine had some character in acute phase and it can predict the serious degree of intoxication, but there was no characteristic findings in chronic phase

  11. CT and MRI appearances of methotrexate leucoencephalopathy

    International Nuclear Information System (INIS)

    Wilks, M.J.; Tie, M.L.K.; Pozza, C.H.

    2002-01-01

    Methotrexate is a well recognised cause of diffuse symmetrical leucoencephalopathy. The widespread use of the drug in chemotherapeutic regimes necessitates awareness of this complication. A case report and a brief literature review is presented. A 20-year-old single woman presented to the Emergency Department with a 6-week history of general malaise, lower back pain and a petechial rash. From investigations including blood picture and bone marrow trephine, the diagnosis of acute lymphoblastic leukaemia (ALL) was made. Three cycles of induction chemotherapy were administered consisting of intravenous cytarabine and hydrocortisone and intrathecal methotrexate. Shortly after the third cycle of induction chemotherapy (6 weeks following diagnosis, 2 days following the last dose of intrathecal methotrexate) she presented with an acute neurological episode consisting of muteness and somnolence. Physical examination showed generalised flaccidity to all muscle groups and generalised loss of reflexes. There were no consistent cranial neuropathies and the patient was not neutropenic. Computed tomography of the brain showed extensive symmetric white matter hypodensity extending throughout the corona radiata and deep white matter tracts especially the external capsules. There was no abnormal enhancement with non-ionic contrast administration or evidence of grey matter involvement. Magnetic resonance imaging was subsequently performed, the fluid attenuated inversion recovery images (FLAIR) and T2-weighted image (T2WI) demonstrated marked white matter hyperintensity; the involvement was more extensive than demonstrated on the CT with additional involvement of the subcortical and cerebellar white matter, the basal ganglia and cortex of the mesial temporal and inferior frontal lobes. Gadolinium was not administered. A follow up study after 4 weeks of steroid and folinic acid therapy showed complete resolution of the white matter hyperintensity on the T2WI and FLAIR sequences

  12. Abdominal retained surgical sponges: CT appearance

    Energy Technology Data Exchange (ETDEWEB)

    Kalovidouris, A.; Kehagias, D.; Moulopoulos, L.; Gouliamos, A.; Pentea, S.; Vlahos, L. [Department of Radiology, University of Athens (Greece)

    1999-09-01

    Retention of surgical sponges is rare. They cause either an aseptic reaction without significant symptoms or an exudative reaction which results in early but nonspecific symptoms. Computed tomography is very useful for recognition of retained sponges. The appearance of retained sponges is widely variable. Air trapping into a surgical sponge results in the spongiform pattern which is characteristic but unfortunately uncommon. A low-density, high-density, or complex mass is found in the majority of cases, but these patterns are not specific. Sometimes, a thin high-density capsule may be seen. Rim or internal calcification is a rare finding. Finally, a radiopaque marker is not a reliable sign. Differentiation from abscess and hematoma is sometimes difficult. (orig.) With 11 figs., 12 refs.

  13. Abdominal retained surgical sponges: CT appearance

    International Nuclear Information System (INIS)

    Kalovidouris, A.; Kehagias, D.; Moulopoulos, L.; Gouliamos, A.; Pentea, S.; Vlahos, L.

    1999-01-01

    Retention of surgical sponges is rare. They cause either an aseptic reaction without significant symptoms or an exudative reaction which results in early but nonspecific symptoms. Computed tomography is very useful for recognition of retained sponges. The appearance of retained sponges is widely variable. Air trapping into a surgical sponge results in the spongiform pattern which is characteristic but unfortunately uncommon. A low-density, high-density, or complex mass is found in the majority of cases, but these patterns are not specific. Sometimes, a thin high-density capsule may be seen. Rim or internal calcification is a rare finding. Finally, a radiopaque marker is not a reliable sign. Differentiation from abscess and hematoma is sometimes difficult. (orig.)

  14. The effect of pitch in multislice spiral/helical CT

    International Nuclear Information System (INIS)

    Wang, G.; Vannier, M.W.

    2000-01-01

    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)

  15. Synthetic ossicular replacements: Normal and abnormal CT appearance

    International Nuclear Information System (INIS)

    Swartz, J.D.; Zwillenberg, S.; Berger, A.S.; Granoff, D.W.; Popky, G.L.

    1986-01-01

    Numerous synthetic ossicular replacements are currently in use. The TORP conducts sound from the newly formed tympanic membrane to the oval window; the PORP is used when the stapes superstructure is maintained, being interposed between the tympanic membrane and the stapes capitulum. In 12 patients the surgical results of ossicular replacement procedures were good, which gave the author the opportunity to study the normal CT appearance. In an additional 10 patients CT was performed before surgical revision. Using CT, they have been able to diagnose subluxation and fibrous tissue fixation. In two patients the CT appearance was unremarkable, but at surgery lateralization of the graft was found, with a nonfunctioning interface

  16. Helical CT for secondary screening of lung cancer

    International Nuclear Information System (INIS)

    Mori, Kiyoshi; Onishi, Tsukasa; Tominaga, Keigo; Kishiro, Izumi; Yokoyama, Kohki.

    1995-01-01

    Helical CT was used on a trial basis for secondary screening of lung cancer, and its clinical usefulness is discussed in this report. The subjects of 157 patients with abnormal shadows on plain chest X-ray images were chosen between November 1993 and August 1994. Imaging parameters used for screening CT were as follows: 50 mA, 120 kV, a couch-top movement speed of 20 mm/s, and a beam width of 10 mm. The entire lung field was scanned during a single breath-hold. Reconstructed images were generated at 10-mm intervals by the 180deg interpolation method, and films were produced. Images of the entire lung field were made during a single breath-hold in all patients. Abnormal shadows were detected in 73 of 157 patients by screening CT. These 73 patients included 14 with lung cancer, 53 with benign lesions, one under observation, and five others. The average diameter of the tumors was 11.1 mm. The lung cancers detected all arose in the periphery, and were classified into stage I (10 patients), stage IIIA (3 patients), and stage IV with bone metastases (1 patient). Lung cancers in clinical stage I (3 patients) and stage IV (1 patient) were difficult to see on plain chest X-ray films. We conclude that screening CT is useful for early diagnosis of lung cancer because the entire lung field can be imaged during a single breath-hold. Therefore, helical CT can be expected to be useful in screening for lung cancer. (author)

  17. Clinical application of the helical CT in patients who are unable to hold their breath

    International Nuclear Information System (INIS)

    Toyama, Yoshihiro; Kimura, Naruhide; Ohkawa, Motoomi; Tanabe, Masatada.

    1997-01-01

    We performed helical CT in eighteen patients who were unable to hold their breath for 10 chest and 8 abdominal regions. Although there were respiratory artifacts in three cases, we could obtain the useful clinical information in all cases. In our experimental examinations, CT value of the phantom by helical scan was lower than that by conventional scan without movement of the phantom. With movement of it, the CT value was further lowered by either scan method, but the lowered rate was smaller by helical scan as the movement becomes faster. We consider that helical CT can be applied to patients who were unable to hold their breath. (author)

  18. Bronchial carcinoid tumor: helical CT and virtual bronchoscopy

    International Nuclear Information System (INIS)

    Diez, Eduardo; Carrascosa, Patricia; Capunay, Carlos; Spinozzi, German; Abramson, Horacio; Berna, Miguel

    2001-01-01

    The authors reported a case of a 61 years old man with recurrent neumonia of the inferior right lobe diagnosed by a chest radiography. A complementary helical CT showed an endobronquial mass on the right intermediate bronchus. Virtual bronchoscopy contributed to a better definition of this lesion, confirmed by a real bronchoscopy. The lesion was diagnosed as a carcinoid tumor by a bronchial biopsy. After surgery (sleeve resection of the tumor) the patient did not show any recurrence of his broncho-neumonic clinical features. (author)

  19. Helical CT defecography; La defecografia con Tomografia Computerizzata spirale

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    Ferrando, R.; Fiorini, G.; Beghello, A.; Cicio, G.R.; Derchi, L.E.; Consigliere, M.; Resasco, M. [Genua Univ., Genua (Italy). Ist. di Radiologia, Cattedra R; Tornago, S. [Genua Univ. Genua (Italy). 2 Clinica Ortopedica

    1999-11-01

    The purpose of this work is to investigate the possible role of Helical CT defecography in pelvic floor disorders by comparing the results of the investigations with those of conventional defecography. The series analyzed consisted of 90 patients, namely 62 women and 28 men, ranging in age 24-82 years. They were all submitted to conventional defecography, and 18 questionable cases were also studied with Helical CT defecography. The conventional examination was performed during the 4 standard phases of resting, squeezing, Valsalva and straining; it is used a remote-control unit. The parameters for Helical CT defecography were: 5 mm beam collimation, pitch 2, 120 KV, 250 m As and 18-20 degrees gantry inclination to acquire coronal images of the pelvic floor. The rectal ampulla was distended with a bolus of 300 mL nonionic iodinated contrast agent (dilution: 3g/cc). The patient wore a napkin and was seated on the table, except for those who could not hold the position and were thus examined supine. Twenty-second helical scans were performed at rest and during evacuation; multiplanar reconstructions were obtained especially on the sagittal plane for comparison with conventional defecographic images. Coronal Helical CT defecography images permitted to map the perineal floor muscles, while sagittal reconstructions provided information on the ampulla and the levator ani. To conclude, Helical CT defecography performed well in study of pelvic floor disorders and can follow conventional defecography especially in questionable cases. [Italian] Scopo di questo lavoro e' ricercare un ruolo per la defeco-TC con apparecchiatura elicoidale nello studio delle malattie del pavimento pelvico confrontandola con i risultati consolidati della defecografia tradizionale. Si sono visionati 90 pazienti, 62 femmine e 28 maschi, con eta' compresa tra 24 e 82 anni, con defecografia tradizionale; di questi, 18 casi con diagnosi dubbia sono stati studiati anche con defeco-TC spirale

  20. Pancreatic changes in cystic fibrosis: CT and sonographic appearances

    International Nuclear Information System (INIS)

    Daneman, A.; Gaskin, K.; Martin, D.J.; Cutz, E.

    1983-01-01

    The computed tomographic (CT) and sonographic appearances of the late stages of pancreatic damage in three patients with cystic fibrosis are illustrated. All three had severe exocrine pancreatic insufficiency with steatorrhea. In two patients CT revealed complete fatty replacement of the entire pancreas. In the third, increased echogenicity of the pancreas on sonography and the inhomogeneous attenuation on CT were interpreted as being the result of a combination of fibrosis, fatty replacement, calcification, and probable cyst formation

  1. The CT appearance of ''reversible'' cerebral pseudoatrophy in anorexia nervosa

    International Nuclear Information System (INIS)

    Boron, Z.; Kozlowska, R.; Grzegorzewski, M.; Nawrot, M.; Bulawska, I.

    1995-01-01

    The CT appearance of ''reversible'' cerebral pseudoatrophy resulting from anorexia nervosa was demonstrated. The CT studies were performed in 3 young women with typical clinical course of anorexia nervosa. In all of them computed tomography revealed dilatation of the subarachnoid fluid space. After 5 months of therapy the follow-up scans have reverted to normal in all cases. (author)

  2. 3D CT versus axial helical CT versus conventional tomography in the classification of acetabular fractures: A ROC analysis

    International Nuclear Information System (INIS)

    Kickuth, Ralph; Laufer, Ulf; Hartung, Guido; Gruening, Christian; Stueckle, Christoph; Kirchner, Johannes

    2002-01-01

    AIM: To assess the diagnostic power of three-dimensional computed tomography (3D CT), axial helical computed tomography (CT) and conventional tomography in the classification of acetabular fractures by interdisciplinary review. MATERIALS AND METHODS: Receiver operating characteristics (ROCs) were assessed for two radiologists and two surgeons blinded to the presence of acetabular fractures in an animal model (a total of 62 porcine hips, 40 of them with artificial acetabular fractures). Main target parameter was the diagnostic accuracy in the classification of the artificial fractures following Judet et al. RESULTS: ROC analysis for radiologists showed A z values of 0·83 for 3D CT, 0·81 for axial helical CT, and 0·78 for conventional tomography; differences between the three techniques were not significant (P = 0·46-0·73). A z values for the surgeons were 0·87 for 3D CT, 0·68 for axial helical CT, and 0·60 for conventional tomography; 3D CT was significantly better than axial helical CT (P = 0·01) and conventional tomography (P = 0·001). The differences between axial helical CT and conventional tomography were not significant (P = 0·37). CONCLUSION: Acetabular fractures are best classified by 3D CT, followed by axial helical CT and conventional tomography when assessed by surgeons. 3D CT did not provide any additional significant benefit in the classification performed by radiologists. Kickuth, R. et al. (2002)

  3. CT appearance of focal fatty infiltration of the liver

    International Nuclear Information System (INIS)

    Halvorsen, R.A.; Korobkin, M.; Ram, P.C.; Thompson, W.M.

    1982-01-01

    Focal fatty infiltration of the liver is an entity that may be confused with liver metastasis on computed tomography (CT). The imaging results and medical records of 16 patients with CT appearance suggestive of focal fatty liver were reviewed, three of whom had the simultaneous presence of metastitic liver disease. Focal fatty liver often has a distinctive appearance with CT, usually with a nonspherical shape, absence of mass effect, and density close to water. Liver metastases are usually round or oval, and unless cystic or necrotic, they have CT attenuation values closer to normal liver parenchyma than water. A radionuclide liver scan almost always resolves any confusion about the differential diagnosis of focal fatty liver: a well defined focus of photon deficiency is due to neoplasm rather than focal fatty infiltration. Sonography sometimes helps to confirm the CT impression, but may be misleading if the diagnosis of focal or diffuse fatty infiltration is not suspected before the examination

  4. Multislice helical CT in the diagnosis of hilar cholangiocarcinoma

    International Nuclear Information System (INIS)

    Yang Li; Zhao Shaohong; Nie Yongkang; Zhao Hong; Fang Jie; Cai Zulong; Yang Zhou; Ying Yifeng

    2005-01-01

    Objective: To investigate the value ofMSCT in observing the direct findings of hilar cholangiocarcinoma1Methods Multislice helical CT studies were performed on the upper abdomen in 19 consecutive patientswith painless jaundice1 Precontrast and dynamic contrast enhanced (25 s phase and 60 s phase) scanswere conducted, and 3D imageswere reconstructed using enhanced raw data in 15 cases1 The direct CT findings of hilar cholangiocarcinoma were studied by three radiologists respectively in a 32scale strategy1 The morphological features and extension of bile duct involvement by hilar cholangiocarcinoma were analyzed1 All the 19 caseswere pathologically p roved as hilar cholangiocarcinoma by surgery (15 cases) and ERCP ( 4 cases) 1 Results The direct findings and extension of hilar cholangiocarcinoma could be demonstrated in 14 out of 15 3D reconstruction images, 8 out of 19 in 25 s phase, and 7 out of 19 in 60 s phase of contrast enhancement scans, respectively ( P < 0105 ) 1 The tumor involving the bile duct was enhanced most remarkablely on 25 s phase, and the bile duct wall thickening, bile duct narrowing or occlusion were demonstrated as the p rimary findings of hilar cholangiocarcinoma1 The intraductal sp read of tumor could be demonstrated as small nodules on the bile duct wall p roximal or distal to the tumor1 Conclusion. The tumor involving the bile duct can be enhanced most remarkablely on 25 s phase after contrast injection1 Multislice helical CT, especially 3D reconstructed images, can be used to detect the direct findings of hilar cholangiocarcinomas and the extension of tumor involving the bile duct. (authors)

  5. Utility of three-dimensional helical CT in the diagnosis of breast cancer

    International Nuclear Information System (INIS)

    Maeda, Yoshiaki; Hata, Yoshinobu; Matsuoka, Shinnichi; Nakajima, Nobuhisa; Ito, Toichi; Osada, Tadahiro; Sano, Fumio

    2004-01-01

    Although utility of three-dimensional (3D) helical CT for preoperative examination of breast cancer has been discussed, the accuracy of the helical CT in diagnosing breast cancer has not been fully evaluated. In this study 56 malignant and 28 benign breast tumors were evaluated preoperatively with 3D-helical CT, and their imaging results were compared with pathological findings of surgical specimens. Helical CT identified the presence of malignancy in 54 out of the 56 cancer cases tested and the sensitivity and specificity in distinguishing between malignant and benign tumors were 82% and 57%, respectively. The sensitivity and specificity in diagnosing the presence of metastatic axillary lymph nodes using helical CT were 70% and 80%, respectively. The sensitivity and specificity in diagnosing the presence of extensive intraductal component (EIC) using helical CT were 71% and 86%, respectively. Helical CT visualized all of the tumors in multifocal breast cancer cases. In conclusion, 3D-helical CT is a useful modality for preoperative examination of breast cancer, especially for assessing axillary lymph node status, and EIC, and will be helpful for conducting sentinel lymph node biopsy (SNLB) and breast-conserving surgery. (author)

  6. Early appearance of SARS on chest CT scan

    International Nuclear Information System (INIS)

    Cheng Xiaoguang; Feng Suchen; Xia Guoguang; Zhao Tao; Gu Xiang; Qu Hui

    2003-01-01

    Objective: To evaluate the early appearance of SARS on chest CT scan and its role in the early diagnosis. Methods: Forty cases of SARS in keeping with the criteria of the Ministry of Health had chest CT scans within 7 days of onset of symptoms, and CR chest X-ray films were available as well. These chest X-rays and CT images were retrospectively reviewed to determine if there were any abnormalities on the images. The lesions on the chest CT images were then further analyzed in terms of the number, location, size, and density. Results: Positive abnormalities on chest CT scans were revealed in all 40 SARS cases. Positive findings on CR chest films were showed in only 25 cases, equivocal in 6, and normal in 9 cases. The main abnormalities seen on CT and X-rays were pulmonary infiltrations varied markedly in severity. 70 % cases had 1 or 2 lesions on chest CT scan, 30 % cases had 3 or more lesions. The lesions seen on chest CT scan tended to be ground-glass opacification, sometimes with consolidation which was very faint and inhomogeneous, easily missed on chest X-rays. Typically the lesions were located in the periphery of the lung, or both central and peripheral lung, but very rare in a pure central location. They were commonly in the shape of patch or ball. Conclusions: Chest CT scan is much more sensitive in detecting the lesions of the lung in SARS. The early appearance of SARS on chest CT scan is characteristic but non-specific, indicating that chest CT scan plays a very important role in the early diagnosis and differential diagnosis of SARS

  7. Helical CT imaging of clinically suspected appendicitis: Correlation of CT and histological findings

    International Nuclear Information System (INIS)

    Wong, S.K.; Chan, L.P.; Yeo, A.

    2002-01-01

    PURPOSE: The diagnosis of appendicitis is traditionally made on the basis of clinical findings supported by laboratory results. The aim of our study was to determine the accuracy and feasibility of using a relatively new technique of computed tomography (CT) using only colonic contrast medium. MATERIALS AND METHODS: A total of 50 patients clinically diagnosed as having appendicitis were prospectively examined before surgery with thin-collimation helical CT from the L3 level to the acetabular roof with only rectally administered colon contrast medium. The hard copy CT images were reviewed jointly by two radiologists and a consensus was reached for each patient. The results were then compared with the surgical and histological findings at appendicectomy. RESULTS: There were 35 true-positives, one false-positive, 12 true-negatives and two false-negatives for CT. This yielded an accuracy of 94%, sensitivity of 95%, specificity of 92%, positive predictive value of 97% and negative predictive value of 86%. The appendix was identified in 45 patients (90%) and obscured by an inflammatory mass in the remaining five. An alternative diagnosis was found in 10 of 12 normal CT examinations (83%). CONCLUSION: Helical CT with rectal contrast medium is a quick, well tolerated and accurate test to diagnose appendicitis. It can offer alternative, possibly non-surgical diagnosis in patients who would otherwise have undergone laparotomy. Wong, S.K. et al. (2002)

  8. CT appearance of congenital defect resembling the Hangman's fracture

    International Nuclear Information System (INIS)

    Williams, J.P. III; Baker, D.H.; Miller, W.A.

    1999-01-01

    Purpose. Congenital defects of C2 are rare and can be confused with Hangman's fractures. CT has been advocated as aiding in differentiation between an acute fracture and congenital defects. Methods. We present a case of a 2-year-old recent accident victim, who was erroneously diagnosed by plain film and CT as having a Hangman's fracture. Results. The CT demonstrated an atypical appearance of a congenital defect. Conclusion. This case shows that the radiographic differentiation between a Hangman's fracture and a congenital defect is more difficult than previously described. (orig.)

  9. Metastatic tumor of the pancreas: helical CT findings

    International Nuclear Information System (INIS)

    Lee, Soon Jin; Lee, Won Jae; Lim, Hyo Keun; Kim, Seung Hoon; Kim, Kyeong Ah; Choi, Sang Hee; Jang, Hyun Jung; Lee, Ji Yeon

    2000-01-01

    To analyze the helical computed tomographic (CT) findings of distant metastatic tumors to the pancreas and to determine the differential points between these and primary pamcreatic carcinomas. We sruveyed 22 patients with metastatic tumor of the pancreas, proven on the basis of clinical and pathological findings. Seventeen patients were men, and five were women, and their ages ranged between 36 and 83 years. Their primary conditions were lung cancer (n=3D15), rectal cancer (n=3D2), melanoma of the foot, chondrosarcoma of the sacrum, cervical cancer, leiomyosarcoma of the uterus, and extragonadal choriocarcinoma of the mediastinum. We retrospectively reviewed the abdominal helical CT findings, analysing the number, location, size and attenuation of masses, as well as secondary change, which included dilatation of the pancreatic and biliary ducts and invasion of peripancreatic tissue or vessels. We also evaluated the differential findings of primary pancreatic cancer. Sixteen patients had a solitary focal mass, while in five, two masses were present. Among the 22 patients, low-density nodular masses were present in 21; in the other, in whom multiple metastasis from chondrosarcoma had occurred, there was dense calcification. The size of metastatic masses varied, ranging from 0.6 to 6 cm in diameter. The pancreatic duct proximal to the mass was dilated in ten cases, while the bile duct was dilated in six. The metastatic masses masses demonstrated no peripancreatic or vascular invasion, though they showed a discrete margin and contour bulging. Single metastasis to the pancreas was most common, and metastatic masses had a discrete margin, with contour bulging. There was no peripancreatic or vascular invasion. If the metastasis involved a single low-attenuated mass, however, with pancreatic or biliary dilatation, it was difficult to differentiate this from primary pancreatic cancer. (author)

  10. CT appearance of the normal appendix in adults

    International Nuclear Information System (INIS)

    Tamburrini, Stefania; Brunetti, Arturo; Brown, Michele; Sirlin, Claude B.; Casola, Giovanna

    2005-01-01

    The aims of this study were to identify (1) the normal range of the appendix on computed tomography (CT), (2) the correlation of patient age and sex with the visibility and appearance of the appendix on CT, and (3) the normal variations in wall thickness, intraluminal content, and location of the appendix. Three hundred seventy-two outpatients underwent abdominopelvic CT. The scans were reviewed on the picture archiving and communication system and appendiceal outer-to-outer wall diameter, wall thickness, location, content and its correlation with appendix diameter were analyzed. The appendix was visualized in 305/372 patients. Its location relative to the cecum was highly variable. The diameter range was 3-10 mm; in 42% of cases the diameter was greater than 6 mm. When the intraluminal content (185/305) was visualized, the diameter was slightly superior to the mean (p=0.0156). In 329 CT scans in which oral contrast material was given, the appendix was filled by contrast material in 74/329 patients. The appendix wall thickness was measurable in 22/305 patients (average 0.15 cm). There is significant overlap between the normal and abnormal CT appearance of the appendix. Consequently the diagnosis of acute appendicitis should be based not only on the appearance of the appendix but also on the presence of secondary signs. (orig.)

  11. Virtual endoscopy post-processing of helical CT data sets

    International Nuclear Information System (INIS)

    Dessl, A.; Giacomuzzi, S.M.; Springer, P.; Stoeger, A.; Pototschnig, C.; Voelklein, C.; Schreder, S.G.; Jaschke, W.

    1997-01-01

    Purpose: The purpose of this work was to test a newly developed, post-processing software for virtual CT endoscopic methods. Virtual endoscopic images were generated from helical CT data sets in the region of the shoulder joint (n=2), the tracheobronchial system (n=3), the nasal sinuses (n=2), the colon (n=2), and the common carotid artery (n=1). Software developed specifically for virtual endoscopy ('Navigator') was used which, after a previous threshold value selection, makes the reconstruction of internal body surfaces possible by an automatic segmentation process. We have evaluated the usage of the software, the reconstruction time for individual images and sequences of images as well as the quality of the reconstruction. All pathological findings of the virtual endoscopy were confirmed by surgery. Results: The post-processing program is easy to use and provides virtual endoscopic images within 50 seconds. Depending of the extent of the data set, virtual tracheobronchoscopy as a cine loop sequence required about 15 minutes. Thorugh use of the threshold value-dependent surface reconstruction the demands on the computer configuration are limited; however, this also created quality problems in image calculation as a consequence of the accompanying loss of data. Conclusions: The Navigator software enables the calculation of virtual endoscopic models with only moderate demands on the hardware. (orig.) [de

  12. Comparison of AMI-25 enhanced MRI and helical dynamic CT in the detection of hepatic lesions

    International Nuclear Information System (INIS)

    Saitou, Kazuhiro; Matsuda, Hiromichi; Fukushima, Hiroaki; Kanzaki, Hiroshi; Hirose, Takashi; Karizaki, Dai; Abe, Kimihiko; Amino, Saburou

    1994-01-01

    We performed AMI-25 enhanced MRI and helical dynamic CT in 12 cases of hepatic lesions. Nine of these were hepatocellular carcinomas. Two cases were metastatic liver tumors (the primary lesion was gastric in one and the other was gallbladder cancer). One case was suspected to be adenomatous hyperplasia. Thirty-two lesions were detected in T2-weighted SE images before AMI-25 administration, while 46 lesions were detected in AMI-25 enhanced MRI images. In particular, AMI-25 enhanced MRI was superior to plain MRI in lesions less than 10 mm in size. A total of 48 lesions were detected in helical dynamic CT. Although AMI-25 enhanced MRI almost equaled helical dynamic CT in the detection of liver tumors, helical dynamic CT was slightly superior to AMI-25 enhanced MRI in the detection of subphrenic lesions. It was possible to know the hemodynamics in each hepatic lesion by helical dynamic CT. AMI-25 enhanced MRI was useful to know the inclusion of reticuloendothelial system, and that yielded different diagnoses in adenomatous hyperplasia and well differentiated hepatocellular carcinoma. Helical dynamic CT was useful for qualitative diagnosis. Both AMI-25 enhanced MRI and helical dynamic CT contributed to the detection of liver tumor and qualitative diagnosis. (author)

  13. Early clinical phase of patient's management after polytrauma using 1- and 4-slice helical CT

    International Nuclear Information System (INIS)

    Kloeppel, R.; Kahn, T.; Schreiter, D.; Dietrich, J.; Josten, C.

    2002-01-01

    In the early clinical phase the comprehensive imaging of patients with multiple trauma using helical CT is already established. Aim of this study was to assess whether MSCT may improve the patient management and the diagnostic results.The procedure is designed as follows: after life-thretening treatment x-ray of chest and ultrasound are carried out in the emergency room. Then the patient is moved to CT. From 1998 to december 2000 241 patients were examined using a single slice helical CT (Somatom plus 4), in 2001 79 patients using a 4-slice helical CT (Somatom VZ, Siemens Med.Sol.). After CT selected radiograms of the extremities were taken.359 of 360 procedures were carried out successfully. Excluding 1 case (death during 1-sl. h CT) all relevant lesions of head, neck, and body were diagnosed. Although the patients had an injury severity score of ∼30. The change from 1slice-helical CT to 4 slice-helical CT allowed us to reduce the stay in the CT room from 28 to 16 min. The total lethality decreased by ∼4%.Advantages for the patient arose from the standardized examination protocol using multislice CT. If integrated in an interdisciplinary management concept, it is a good compromise between examination time, comprehensive diagnostic imaging, life-saving therapeutic procedures, and therapy planning. (orig.) [de

  14. Nodular focal fatty infiltration of the liver: CT appearance

    International Nuclear Information System (INIS)

    Baker, M.E.; Silverman, P.M.

    1985-01-01

    Focal fatty infiltration of the liver is a well recognized entity generally characterized by a nonspherical, low-density area without significant mass effect. CT usually distinguishes this from focal liver processes such as abscess or metastasis by its sharply marginated, geographic pattern and lack of mass effect on hepatic and portal veins. Recently, the authors formed a CT scan of the liver in one patient in whom fatty infiltration appeared nodular or rounded. The clinical presentation and radiographic and pathologic features form the basis of this report

  15. Intraosseous lipomata in Paget's disease: an unusual CT appearance

    International Nuclear Information System (INIS)

    Robbie, M.J.; Pratsis, K.K.; Lockie, D.J.

    1991-01-01

    A case of multiple intraosseous lumbar vertebral lipomata is reported occurring in the prescence of Paget's disease. The pathology and radiology are correlated. An 84 year old man with Paget's disease presented after a cerebrovascular accident which caused him a mild right hemiparesis. Lumbar vertebral lesions were noted incidentally on abdominal radiographs and a CT scan was performed to define the abnormal areas. CT appearance favoured a slow growing non-invasive lesion. However, it failed to show the lower attenuation expected of a fatty lesion such as a lipoma. It is estimated that CT can be diagnostic if it does show fat level attenuation while Magnetic Resonance Imaging can define the lesion in the sagittal and coronal planes as well as provide the signal characteristics of fat (high signal on T1 and T2 weighted images) irrespective of its myxoid ground substance content

  16. Analysis of aliasing artifacts in 16-slice helical CT

    International Nuclear Information System (INIS)

    Chen Wei; Liu Jingkang; Ou Xiaoguang; Li Wenzheng; Liao Weihua; Yan Ang

    2006-01-01

    Objective: To recognize the features of aliasing artifacts on CT images, and to investigate the effects of imaging parameters on the magnitude of this artifacts. Methods: An adult dry skull was placed in a plastic water-filled container and scanned with a PHILIPS 16-slice helical CT. All the acquired transaxial images by using several different acquisition or reconstruction parameters were examined for comparative assessment of the aliasing artifacts. Results: The aliasing artifacts could be seen in most instances and characterized as the spokewise patterns emanating from the edges of high contrast structure as its radius varies sharply in the longitudinal direction. The images that scanned with pitch of 0.3, 0.6 and 0.9, respectively, showed aliasing artifacts, and its severities increased with pitches escalated (detector combination 16 x 1.5, reconstruction thickness 2 mm); There were more significant aliasing artifacts on the images reconstructed with 0.8 mm slice width compared with 1-mm slice width, and no aliasing artifacts were observed on the images reconstructed with 2-mm slice width (detector combination 16 x 0.75, pitch 0.6); No artifacts were perceived on the images scanned with detector combination 16 x 0.75, while presented evidently with the use of detector combination 16 x 1.5 (pitch 0.6, reconstruction thickness 2 mm); The degrees of aliasing artifacts were unaltered when reconstruction interval and tube current changed. Conclusions: Aliasing artifacts are caused by undersampling. When the operator choose the thinner sampling thickness, lower pitch and a much wider reconstruction thickness judiciously, aliasing artifacts could be effectively mitigated or suppressed. (authors)

  17. The evaluation of gallbladder contractibility for volume measurement by helical 3D-CT-cholangiography

    International Nuclear Information System (INIS)

    Hanaguri, Katsuro; Kimura, Hideaki; Kayashima, Yasuyo; Suemoto, Kouichiro; Makihata, Hiroshi; Maruhashi, Akira; Ohya, Toshihide; Ito, Katsuhide; Shen, Yun.

    1997-01-01

    As a new application of helical (spiral) scan, volume measurement has received a significant interest. Although it is important to evaluate gallbladder contractibility to decide on a treatment plan for a gallbladder lesion, qualitative analysis of gallbladder contractibility is very difficult owing to the fact that the volume of gallbladder can not be measured using usual DIC examination (plain X-P and tomography). In this study, the accuracy of volume measurement of helical CT was checked firstly by gallbladder phantom experiments. Then 128 cases of volume measurement of helical 3D CT Cholangiography (DIC-CT) were performed. Under the conditions of optimized scan technique (3 mm TH, 3 mm/s, 1 mm recon interval, Hispeed, GEMS), the difference of contractibility was obtained between clinical cases with and without thick wall. The experiment has shown that helical 3D CT volume measurement is very simple and highly accurate method which is useful for the evaluation of gallbladder contractibility. (author)

  18. CT appearances of mucosa-associated lymphoid tissue (MALT) lymphoma

    International Nuclear Information System (INIS)

    Kessar, P.; Norton, A.; Rohatiner, A.Z.S.; Lister, T.A.; Reznek, R.H.

    1999-01-01

    Mucosa-associated lymphoid tissue (MALT) lymphoma is a low-grade lymphoma that differs from high-grade non-Hodgkin lymphoma both clinically and histologically. The CT appearances of MALT lymphoma are described. Of 40 patients referred with biopsy-proven MALT lymphoma, only seven had not had gastrectomy or chemotherapy prior to CT examination. The CT scans of these seven cases were analysed for the degree and extent of gastric wall thickening, enlargement of abdominal and extra-abdominal lymph nodes, and presence of extranodal disease. In all patients the stomach was distended with oral contrast medium and scans performed at narrow collimation, after intravenous administration of 20 mg hyoscine butylbromide. In six patients focal thickening of the gastric wall was 1 cm or less. One patient had thickening of over 4 cm. There was no enlargement of abdominal or extra-abdominal lymph nodes or extension to adjacent organs. Thus on CT, at presentation, MALT lymphoma results in minimal gastric wall thickening, unlike high-grade non-Hodgkin lymphoma, which typically causes bulky gastric disease, nodal enlargement and extension into adjacent organs. CT is therefore of limited value in monitoring response to treatment. With disease greater than minimal thickening, transformation to a higher grade should be considered. (orig.)

  19. The CT appearance of the superior intercostal veins

    International Nuclear Information System (INIS)

    Lund, G.

    1982-01-01

    The CT appearance of the superior intercostal veins is described. The veins are more frequently seen on the right side. The right superior intercostal vein should not be misinterpreted as a paraspinal mass when it is large or bulges into the contour of the right lung. A case of stenosis of the left brachiocephalic vein is shown, where the left superior intercostal vein serves as a collateral. (orig.)

  20. CT and radiographic appearance of extracranial Onyx® embolization

    International Nuclear Information System (INIS)

    Jia, J.B.; Green, C.S.; Cohen, A.J.; Helmy, M.

    2015-01-01

    Onyx ® (ev3, Irvine, CA, USA) is a liquid embolic agent composed of ethylene vinyl alcohol copolymer dissolved in dimethyl sulphoxide used for the treatment of intracranial arteriovenous malformations. Onyx is a preferred embolizing agent due to its unique properties, non-adhesive nature, and durability. In addition to its approved intracranial application, Onyx is also being used successfully in extracranial embolization in areas including extracranial aneurisms and vascular malformations, trauma, gastrointestinal bleeding, and neoplasms. Because of its increasing utilization, it is important for reporting radiologists to be able to recognize its extracranial appearance across different imaging techniques and to be familiar with its uses. The goal of this review is to describe the extracranial uses of Onyx and its appearance in various extracranial locations at radiography and CT, while providing didactic examples. Onyx appears radiodense at CT and plain radiography and has a curvilinear pattern following the expected path of the vessel embolized. At CT, Onyx creates streak artefact that may obstruct the view of surrounding tissues consistent with descriptions of other tantalum devices

  1. Three-dimensional helical CT for treatment planning of breast cancer

    Energy Technology Data Exchange (ETDEWEB)

    Hiramatsu, Hideko; Enomoto, Kohji; Ikeda, Tadashi [Keio Univ., Tokyo (Japan). School of Medicine] [and others

    1999-01-01

    The role of three-dimensional (3D) helical CT in the treatment planning of breast cancer was evaluated. Of 36 patients examined, 30 had invasive ductal carcinoma, three had invasive lobular carcinoma, one had DCIS, one had DCIS with minimal invasion, and 1 had Paget`s disease. Patients were examined in the supine position. The whole breast was scanned under about 25 seconds of breath-holding using helical CT (Proceed, Yokogawa Medical Systems, or High-speed Advantage, GE Medical Systems). 3D imaging was obtained with computer assistance (Advantage Windows, GE Medical Systems). Linear and/or spotty enhancement on helical CT was considered to suggest DCIS or intraductal spread in the area surrounding the invasive cancer. Of 36 patients, 24 showed linear and/or spotty enhancement on helical CT, and 22 of those 24 patients had DCIS or intraductal spread. In contrast, 12 of 36 patients were considered to have little or no intraductal spread on helical CT, and eight of the 12 patients had little or no intraductal spread on pathological examination. The sensitivity, specificity, and accuracy rates for detecting intraductal spread on MRI were 85%, 80%, and 83%, respectively. 3D helical CT was considered useful in detecting intraductal spread and planning surgery, however, a larger study using a precise correlation with pathology is necessary. (author)

  2. Helical CT in the primary trauma evaluation of the cervical spine: an evidence-based approach

    Energy Technology Data Exchange (ETDEWEB)

    Blackmore, C.C. [Washington Univ., Seattle, WA (United States). Dept. of Radiology; Center for Cost and Outcomes Research, Univ. of Washington, Seattle (United States); Dept. of Radiology, Harborview Medical Center, Seattle, WA (United States); Mann, F.A. [Washington Univ., Seattle, WA (United States). Dept. of Radiology; Harborview Injury Prevention and Research Center, University of Washington, Seattle (United States); Wilson, A.J. [Washington Univ., Seattle, WA (United States). Dept. of Radiology

    2000-11-01

    This review provides a summary of the cost-effectiveness, clinical utility, performance, and interpretation of screening helical cervical spine CT for trauma patients. Recent evidence supports the use of helical CT as a cost-effective method for screening the cervical spine in high-risk trauma patients. Screening cervical spine CT can be performed at the time of head CT to lower the cost of the evaluation, and when all short- and long-term costs are considered, CT may actually save money when compared with traditional radiographic screening. In addition to having higher sensitivity and specificity for cervical spine injury, CT screening also allows more rapid radiological clearance of the cervical spine than radiography. Patients who are involved in high-energy trauma, who sustain head injury, or who have neurological deficits are candidates for CT screening. Screening with CT may enhance detection of other potentially important injuries of the cervical region. (orig.)

  3. Three-dimensional-CT imaging of colorectal disease with thin collimation helical CT scanning

    International Nuclear Information System (INIS)

    Ogura, Toshihiro; Koizumi, Koichi; Sakai, Tatsuya; Kai, Shunkichi; Takatsu, Kazuaki; Maruyama, Masakazu

    1998-01-01

    We have conducted research on three-dimensional (3D)-CT-colonoscopy with thin collimation helical CT scanning over the past three years. This has lately become a subject of special interest. 3D-CT-colonoscopy has three kinds of visualizing methods depending on the threshold setting of CT values. The first one is the virtual endoscopy method which is displayed in a similar fashion to colonoscopic images. The second one is the air image method using the air in the digestive tract as a contrast medium. The third one is the pseudo-tract method which has characteristics of both virtual endoscopy and the air image method and visualizes in a shape of the digestive tract. The image visualized by 3D-CT-colonoscopy is similar to that of conventional colonoscopy and barium enema study, which is obtained with minimal invasion to patients. Obvious advanced carcinomas were easily visualized, and even a small flat polyp measuring 5 mm in size, was able to be observed retrospectively. The characteristics of our method are that we can easily make an examination in a short time and with little dependence on expert technique. Also patients have little discomfort compared to that experienced during colonoscopy and barium enema study. Important features are as follows; long calculation time, insufficient air insufflation, fecal material in the patient''s bowel, whole abdominal scan, and spatial resolution. In the near future, a multislice CT scanner system will have ability to overcome these problems. Therefore, 3D-CT-colonoscopy might be applied in the future for first line examination as a mass screening for colorectal carcinoma. (author)

  4. Diagnostic value of triphasic incremental helical CT in early and progressive gastric carcinoma

    International Nuclear Information System (INIS)

    Gao Jianbo; Yan Xuehua; Li Mengtai; Guo Hua; Chen Xuejun; Guan Sheng; Zhang Xiefu; Li Shuxin; Yang Xiaopeng

    2001-01-01

    Objective: To investigate helical CT enhancement characteristics of gastric carcinoma, and the diagnostic value and preoperative staging of gastric carcinoma with triphasic incremental helical CT of the stomach with water-filling method. Methods: Both double-contrast barium examination and triphasic incremental helical CT of the stomach with water-filling method were performed in 46 patients with gastric carcinoma. Results: (1) Among these patients, normal gastric wall exhibited one layered structure in 18 patients, two or three layered structure in 28 patients in the arterial and portal venous phase. (2) Two cases of early stomach cancer showed marked enhancement in the arterial and portal venous phase and obvious attenuation of enhancement in the equilibrium phase. On the contrary, 32 of the 44 advanced gastric carcinoma was showed marked enhancement in the venous phase compared with the arterial phase ( t = 4.226, P < 0.05). (3) The total accuracy of triphasic incremental helical CT in determining TNM-staging was 81.0%. Conclusion: Different types of gastric carcinoma have different enhancement features. Triphases incremental helical CT is more accurate than conventional CT in the preoperative staging of gastric carcinoma

  5. Orthotopic neobladder reconstrution: postoperative CT appearance, complications and potential pitfalls

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Su Lim; Jung, Seung Eun; Im, Yeon Soo; Lee, Jae Mun; Lee, Ji Youl; Yoon, Moon Soo; Hahn, Seong Tai [The Catholic University of Korea College of Medicine, Seoul (Korea, Republic of)

    2003-08-01

    To evaluate the postoperative CT appearance, complications and potential pitfalls of radical cystectomy with orthotopic neobladder reconstruction. We examined 46 patients [43 men and 3 women aged 34-72 (mean, 56.7) years] who had undergone neobladder reconstruction (ileocolic neobladder in 25 patients and ileal-W neobladder in 21). The CT scans were assessed in terms of their depiction of normal anatomy, namely the shape, location and internal architecture of the neobladder, the location of bladder bases, and the ureteral course. Early and late complications were also assessed. The characteristics of ileocolic neobadder were a right-side location, a lobulated outer margin, interal projections due to haustra or plication, a base in the retropubis, and right-side insertion of both ureters. In contrast, the characteristics of an ileal-W neobladder were a central location, an ovoid shape, nodular thickening at the ureteral insertion site, internal projections due to plication, and a retropubic bladder base. Early complications included hematoma with abscess formation (n=2), and postoperative peritonitis (n=1), while late complications were hydronephrosis due to stricture ar the ureteral anastomotic site (n=16), tumor recurrence at this site (n=1), distal ureteral stone (n=1), mucus urinary retention (n=1), incisional hernia (n=2), tumor recurrence in the pelvic side wall (n=1), carcinomatosis peritonei (n=1), and liver metastasis (n=2). A knowledge of normal anatomic changes is essential for the accurate interpretation of CT scans. CT is a useful modality of the evaluation of postoperative change and the complications occurring in patients who have undergone radial cystectomy with othotopic neobladder reconstruction.

  6. Helical 3D-CT images of soft tissue tumors in the hand

    Energy Technology Data Exchange (ETDEWEB)

    Otani, Kazuhiro; Kikuchi, Hiraku; Tan, Akihiro; Hamanishi, Chiaki; Tanaka, Seisuke [Kinki Univ., Osaka-Sayama (Japan). School of Medicine

    2000-02-01

    X-ray, ultrasonograph CT, MRI and angiography are used to detect tumoral lesions. Recently, helical CT has been revealed to be a useful method for the diagnosis and preoperative evaluation of soft tissue tumors, by which high quality and accurate three dimensional (3D) images can be obtained quickly. We analyzed the preoperative 3D-CT images of soft tissue tumors in the hands of 11 cases (hemangioma in 6 cases, giant cell tumor, lipoma, angiofibroma, chondrosarcoma and malignant fibro-histiocytoma in one case each). Enhanced 3D-CT clearly visualized hemangiomas and solid tumors from the surrounding tissues. The tumors could easily be observed from any direction and color-coded according to the CT number. Helical 3D-CT was thus confirmed to be useful for the diagnosis and preoperative planning by indicating the details of tumor expansion into surrounding tissues. (author)

  7. The evaluation study of helical CT for hepatocellular carcinoma with microwave coagulation treatment

    International Nuclear Information System (INIS)

    Zheng Keguo; Xu Dasheng; Xie Xiaoyan; Peng Zhenpeng

    2002-01-01

    Objective: To study the helical CT signs of the hepatocellular carcinoma (HCC) after percutaneous microwave coagulation therapy (PMCT) and to evaluate the correlation between the helical CT signs and the therapeutic effect of HCC. Methods: The helical CT signs were analyzed in 22 cases with 26 lesions of the hepatocellular carcinoma that were treated with PMCT under ultrasonic guidance. Results: In 21 lesions, no enhancement was detected in the lesion border or inside the lesion at hepatic arterial phase (HAP) and portal venous phase (PVP). In 7 lesions, the slight or marked patchy enhancement was revealed in the surrounding liver of the lesions in HAP. In 5 lesions, nodular enhancement was found in the lesion border or inside the lesion in HAP. Conclusion: The dual-phase helical CT might be accurate in judging the therapeutic effect of HCC after PMCT. If no enhancement was showed in the lesions in the dual-phase helical CT, it indicated that no tumor survived. If slight or marked patchy pattern enhancement was revealed in the surrounding liver of the lesions in HAP, it was a normal reaction after PMCT. If nodular enhancement was found in the lesion border or inside the lesion in HAP, it indicated that the tumor partially survived

  8. Pitch dependence of longitudinal sampling and aliasing effects in multi-slice helical computed tomography (CT)

    International Nuclear Information System (INIS)

    La Riviere, Patrick J.; Pan Xiaochuan

    2002-01-01

    In this work, we investigate longitudinal sampling and aliasing effects in multi-slice helical CT. We demonstrate that longitudinal aliasing can be a significant, complicated, and potentially detrimental effect in multi-slice helical CT reconstructions. Multi-slice helical CT scans are generally undersampled longitudinally for all pitches of clinical interest, and the resulting aliasing effects are spatially variant. As in the single-slice case, aliasing is shown to be negligible at the isocentre for circularly symmetric objects due to a fortuitous aliasing cancellation phenomenon. However, away from the isocentre, aliasing effects can be significant, spatially variant, and highly pitch dependent. This implies that measures more sophisticated than isocentre slice sensitivity profiles are needed to characterize longitudinal properties of multi-slice helical CT systems. Such measures are particularly important in assessing the question of whether there are preferred pitches in helical CT. Previous analyses have generally focused only on isocentre sampling patterns, and our more global analysis leads to somewhat different conclusions than have been reached before, suggesting that pitches 3, 4, 5, and 6 are favourable, and that half-integer pitches are somewhat suboptimal. (author)

  9. Developmental venous anomalies: appearance on whole-brain CT digital subtraction angiography and CT perfusion

    International Nuclear Information System (INIS)

    Hanson, Eric H.; Roach, Cayce J.; Ringdahl, Erik N.; Wynn, Brad L.; DeChancie, Sean M.; Mann, Nathan D.; Diamond, Alan S.; Orrison, William W.

    2011-01-01

    Developmental venous anomalies (DVA) consist of dilated intramedullary veins that converge into a large collecting vein. The appearance of these anomalies was evaluated on whole-brain computed tomography (CT) digital subtraction angiography (DSA) and CT perfusion (CTP) studies. CT data sets of ten anonymized patients were retrospectively analyzed. Five patients had evidence of DVA and five age- and sex-matched controls were without known neurovascular abnormalities. CT angiograms, CT arterial-venous views, 4-D CT DSA and CTP maps were acquired on a dynamic volume imaging protocol on a 320-detector row CT scanner. Whole-brain CTP parameters were evaluated for cerebral blood flow (CBF), cerebral blood volume (CBV), time to peak (TTP), mean transit time (MTT), and delay. DSA was utilized to visualize DVA anatomy. Radiation dose was recorded from the scanner console. Increased CTP values were present in the DVA relative to the unaffected contralateral hemisphere of 48%, 32%, and 26%; and for the control group with matched hemispheric comparisons of 2%, -10%, and 9% for CBF, CBV, and MTT, respectively. Average effective radiation dose was 4.4 mSv. Whole-brain DSA and CTP imaging can demonstrate a characteristic appearance of altered DVA hemodynamic parameters and capture the anomalies in superior cortices of the cerebrum and the cerebellum. Future research may identify the rare subsets of patients at increased risk of adverse outcomes secondary to the altered hemodynamics to facilitate tailored imaging surveillance and application of appropriate preventive therapeutic measures. (orig.)

  10. Developmental venous anomalies: appearance on whole-brain CT digital subtraction angiography and CT perfusion

    Energy Technology Data Exchange (ETDEWEB)

    Hanson, Eric H. [Advanced Medical Imaging and Genetics (Amigenics), Las Vegas, NV (United States); Touro University Nevada College of Osteopathic Medicine, Henderson, NV (United States); University of Nevada Las Vegas, Department of Health Physics and Diagnostic Sciences, 4505 Maryland Parkway, Box 453037, Las Vegas, NV (United States); Amigenics, Inc, Las Vegas, NV (United States); Roach, Cayce J. [Advanced Medical Imaging and Genetics (Amigenics), Las Vegas, NV (United States); University of Nevada Las Vegas, School of Life Sciences, Las Vegas, NV (United States); Ringdahl, Erik N. [University of Nevada Las Vegas, Department of Psychology, Las Vegas, NV (United States); Wynn, Brad L. [Family Medicine Spokane, Spokane, WA (United States); DeChancie, Sean M.; Mann, Nathan D. [Touro University Nevada College of Osteopathic Medicine, Henderson, NV (United States); Diamond, Alan S. [CHW Nevada Imaging Company, Nevada Imaging Centers, Spring Valley, Las Vegas, NV (United States); Orrison, William W. [Touro University Nevada College of Osteopathic Medicine, Henderson, NV (United States); University of Nevada Las Vegas, Department of Health Physics and Diagnostic Sciences, 4505 Maryland Parkway, Box 453037, Las Vegas, NV (United States); CHW Nevada Imaging Company, Nevada Imaging Centers, Spring Valley, Las Vegas, NV (United States); University of Nevada School of Medicine, Department of Medical Education, Reno, NV (United States)

    2011-05-15

    Developmental venous anomalies (DVA) consist of dilated intramedullary veins that converge into a large collecting vein. The appearance of these anomalies was evaluated on whole-brain computed tomography (CT) digital subtraction angiography (DSA) and CT perfusion (CTP) studies. CT data sets of ten anonymized patients were retrospectively analyzed. Five patients had evidence of DVA and five age- and sex-matched controls were without known neurovascular abnormalities. CT angiograms, CT arterial-venous views, 4-D CT DSA and CTP maps were acquired on a dynamic volume imaging protocol on a 320-detector row CT scanner. Whole-brain CTP parameters were evaluated for cerebral blood flow (CBF), cerebral blood volume (CBV), time to peak (TTP), mean transit time (MTT), and delay. DSA was utilized to visualize DVA anatomy. Radiation dose was recorded from the scanner console. Increased CTP values were present in the DVA relative to the unaffected contralateral hemisphere of 48%, 32%, and 26%; and for the control group with matched hemispheric comparisons of 2%, -10%, and 9% for CBF, CBV, and MTT, respectively. Average effective radiation dose was 4.4 mSv. Whole-brain DSA and CTP imaging can demonstrate a characteristic appearance of altered DVA hemodynamic parameters and capture the anomalies in superior cortices of the cerebrum and the cerebellum. Future research may identify the rare subsets of patients at increased risk of adverse outcomes secondary to the altered hemodynamics to facilitate tailored imaging surveillance and application of appropriate preventive therapeutic measures. (orig.)

  11. Identification of the segmental artery feeding the anterior spinal artery. Correlation between helical CT and angiography

    International Nuclear Information System (INIS)

    Nishimura, Jun-ichi; Lee, Jin; Koike, Shigeomi

    2005-01-01

    We investigated whether identification of the segmental artery feeding the anterior spinal artery (ASA) is possible by single-slice helical CT. Enhanced CT and angiography were performed in 14 patients with retroperitoneal, liver, or bone tumor. A single-slice helical CT scanner with 7 mm collimation and a 1.0 helical pitch was used. Scanning was started 25 to 30 sec after an intravenous injection of 100 ml of contrast medium at a rate of 3.0 ml/sec. We predicted the segmental artery feeding the ASA in all 14 patients using enhanced CT images. In 12 of the 14 patients, the segmental artery feeding the ASA was angiographically identified. In 7 of these 12 patients, the level of the segmental artery feeding the ASA identified on segmental arteriogram was the same level as that predicted by enhanced CT. In the remaining 5 patients, the level of the segmental artery feeding the ASA identified on segmental arteriogram was one level higher or lower than the predicted spinal level. We could identify the segmental artery feeding the ASA by detailed examination and interpretation of single-slice helical CT images. (author)

  12. Low-dosage helical CT applications for chest medical checkup and lung cancer screening

    International Nuclear Information System (INIS)

    Wang Ping; Cui Fa; Liang Huanqing; Zheng Minfei

    2005-01-01

    Objective: A discussion on low-dosage helical CT applications on chest medical checkup and lung cancer screening. Methods: On the 100 chest medical check up with three different of protocols, including standard-dosage (the tube current was 230 mAs) were compared with low-dose (tube current was 50 mAs or 30 mAs). Results: Low-dosage helical CT scan provides excellent images. In 100 chest medical checkup, 39 nodules or masses were revealed, enlarged lymph node was noted in 1 case; emphysema or bullae was demonstrated in 3 segments; thickening of bronchial wall was shown in 2 cases; and localized pleural thickening was found in 1 case. Conclusion: In chest checkup or lung cancer screening low-dosage helical CT (tube current 30 mAs) will not only guarantee image quality but also reduce the radiation dose during the examination. (authors)

  13. Tuberculous radiculomyelitis (arachnoiditis): myelographic (and CT myelographic) appearances

    International Nuclear Information System (INIS)

    Phadke, R.V.; Kohli, A.; Jain, V.K.; Gupta, R.K.; Gujral, R.B.

    1994-01-01

    Tuberculous radiculomyelitis (arachnoiditis) remains one of the important causes of paraplegia in India. The diagnosis usually rests on clinical history and examination, and on laboratory findings in the cerebro-spinal fluid (CSF). Few descriptive reports are available of the myelographic appearance, with water-soluble contrast media, in tuberculous radiculomyelitis (arachnoiditis). A retrospective review of 21 myelograms and 10 computed tomographic (CT) myelograms, in 14 patients with tuberculous radiculomyelitis, was carried out, with a view to describing, in detail, the radiographic features. An attempt was made to assess the use of the radiologic procedures in diagnosis and follow up in these patients. Conventional myelographic findings included block (8/14), irregular sub-arachnoid space (9/14), filling defects (8/14), sluggish contrast flow (2/14), root thickening (3/14) and atrophic cord (2/14). Computed tomographic myelography showed reduced contrast density in portions of the opacified CSF ring around the cord in affected region (6/7) and, in addition, demonstrated septa and adhesions. Intravenous contrast CT was not found to be useful (2/2). Follow-up studies showed partial resolution (3/6), deterioration (1/6) and status quo of radiological findings (2/6). Although these changes can be seen in chronic radiculomyelitis (arachnoiditis) from other causes, such as leukaemic infiltration/lymphoma, other chronic central nervous system infections and iatrogenic causes, including repeated intrathecal injections, conventional myelography appeared to be useful for diagnosis and follow up in tuberculous radiculomyelitis (arachnoiditis). 12 refs., 1 tabs., 10 figs

  14. Pancreatic adenocarcinoma: dual-phase helical CT with surgical and histopathologic correlation

    International Nuclear Information System (INIS)

    Kim, Eun A; Yoon, Kwon Ha; Park, Seong Hoon; Yun, Ki Jung; Won, Jong Jin

    2003-01-01

    To determine the accuracy of dual-phase helical CT in assessing the resectability of pancreatic ductal adenocarcinoma, and to correlate the CT findings with the surgical and histopathologic findings. Thirty patients with pathologically proven cancer of the pancreas underwent arterial-and portal-phase helical CT scanning, and in the two of these, single-level dynamic CT was performed during celiac and superior mesenteric arteriography. In 17 patients who underwent surgery for potentially resectable cancer of the pancreatic head, tumor resectability was assessed. The CT findings were analyzed and correlated with these of surgery and histopathology. In 13 (76%) of the 17 patients who underwent surgery, tumors were resectable. Their average size was 2.76 cm (arterial phase), 2.30 cm (portal phase), and 2.48 cm (pathologically determined) and the overall accuracy of helical CT for assessing resectability was 87%. In all patients, the central portion of the tumors exhibited hypoattenuation at both phases; the peripheral portion showed hypoattenuation at the arterial phase and iso- (n=10) or hyperattenuation (n=3) at the portal phase. Single-level dynamic CT depicted a persistently hypoattenuating central portion and progressive and prolonged enhancement of the periphery. CT-histopathologic correlation showed that central hypoattenuation indicated the presence of tumor cells, necrosis (n=3) and mucin (n=4), while the peripheral iso- or hyperattenuated areas seen at the portal phase represented fibrosis and inflammatory infiltration. Histopathologic examination revealed tumoral infiltration of peripancreatic fat tissue (n=11) and microvascular invasion of major peripancreatic vessels (n=7). The dual-phase helical CT is useful in the determination of resectability in pancreas cancer and CT findings represent well the histopathologic features of pancreas cancer

  15. Pancreatic adenocarcinoma: dual-phase helical CT with surgical and histopathologic correlation

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Eun A; Yoon, Kwon Ha; Park, Seong Hoon; Yun, Ki Jung; Won, Jong Jin [Wonkwang University School of Medicine, Iksan (Korea, Republic of)

    2003-03-01

    To determine the accuracy of dual-phase helical CT in assessing the resectability of pancreatic ductal adenocarcinoma, and to correlate the CT findings with the surgical and histopathologic findings. Thirty patients with pathologically proven cancer of the pancreas underwent arterial-and portal-phase helical CT scanning, and in the two of these, single-level dynamic CT was performed during celiac and superior mesenteric arteriography. In 17 patients who underwent surgery for potentially resectable cancer of the pancreatic head, tumor resectability was assessed. The CT findings were analyzed and correlated with these of surgery and histopathology. In 13 (76%) of the 17 patients who underwent surgery, tumors were resectable. Their average size was 2.76 cm (arterial phase), 2.30 cm (portal phase), and 2.48 cm (pathologically determined) and the overall accuracy of helical CT for assessing resectability was 87%. In all patients, the central portion of the tumors exhibited hypoattenuation at both phases; the peripheral portion showed hypoattenuation at the arterial phase and iso- (n=10) or hyperattenuation (n=3) at the portal phase. Single-level dynamic CT depicted a persistently hypoattenuating central portion and progressive and prolonged enhancement of the periphery. CT-histopathologic correlation showed that central hypoattenuation indicated the presence of tumor cells, necrosis (n=3) and mucin (n=4), while the peripheral iso- or hyperattenuated areas seen at the portal phase represented fibrosis and inflammatory infiltration. Histopathologic examination revealed tumoral infiltration of peripancreatic fat tissue (n=11) and microvascular invasion of major peripancreatic vessels (n=7). The dual-phase helical CT is useful in the determination of resectability in pancreas cancer and CT findings represent well the histopathologic features of pancreas cancer.

  16. Contrast-enhanced helical CT of the pancreas. Optimal timing of imaging for pancreatic tumor evaluation

    International Nuclear Information System (INIS)

    Koide, Kazuki; Sekiguchi, Ryuzo

    2001-01-01

    We performed three-phase helical CT in patients suspected pancreatic tumors and investigated the optimal timing of imaging for evaluation of the pancreatic mass. The pancreatic-phase was superior in detecting pancreatic tumors, including islet cell tumors that may show strong enhancement. However, portal vein-phase imaging was also superior in 16.7% of our patients. Taking into account examination for hepatic metastasis, helical CT of any pancreatic tumor should include images obtained in the pancreatic and portal vein phases. (author)

  17. Rupture of an aneurysm of the coronary sinus of Valsalva: diagnosis by helical CT angiography

    International Nuclear Information System (INIS)

    Azarine, A.; Lions, C.; Beregi, J.P.; Koussa, M.

    2001-01-01

    A 75-year-old man presented with a 5-day history of upper chest discomfort. On auscultation, there was a systolic murmur in the left parasternal area that radiated to the apex. Electrocardiography showed flat T waves in the anterior precordial leads. Chest X ray revealed mediastinal enlargement. Transthoracic echocardiography showed a dilated proximal ascending aorta with moderate aortic regurgitation. A contrast-enhanced helical CT scan, performed to eliminate an aortic dissection, showed a ruptured left coronary sinus of Valsalva aneurysm, confirmed at surgery. This case highlights the fact that helical CT, in patients with suspected aortic dissection, may reveal other pathology that accounts for the clinical presentation. (orig.)

  18. Rupture of an aneurysm of the coronary sinus of Valsalva: diagnosis by helical CT angiography

    Energy Technology Data Exchange (ETDEWEB)

    Azarine, A.; Lions, C.; Beregi, J.P. [Dept. of Vascular Surgery, Hopital Cardiologique, CHRU de Lille (France); Koussa, M. [Dept. of Vascular Radiology, Hopital Cardiologique, CHRU de Lille (France)

    2001-08-01

    A 75-year-old man presented with a 5-day history of upper chest discomfort. On auscultation, there was a systolic murmur in the left parasternal area that radiated to the apex. Electrocardiography showed flat T waves in the anterior precordial leads. Chest X ray revealed mediastinal enlargement. Transthoracic echocardiography showed a dilated proximal ascending aorta with moderate aortic regurgitation. A contrast-enhanced helical CT scan, performed to eliminate an aortic dissection, showed a ruptured left coronary sinus of Valsalva aneurysm, confirmed at surgery. This case highlights the fact that helical CT, in patients with suspected aortic dissection, may reveal other pathology that accounts for the clinical presentation. (orig.)

  19. Partial volume and aliasing artefacts in helical cone-beam CT

    International Nuclear Information System (INIS)

    Zou Yu; Sidky, Emil Y; Pan, Xiaochuan

    2004-01-01

    A generalization of the quasi-exact algorithms of Kudo et al (2000 IEEE Trans. Med. Imaging 19 902-21) is developed that allows for data acquisition in a 'practical' frame for clinical diagnostic helical, cone-beam computed tomography (CT). The algorithm is investigated using data that model nonlinear partial volume averaging. This investigation leads to an understanding of aliasing artefacts in helical, cone-beam CT image reconstruction. An ad hoc scheme is proposed to mitigate artefacts due to the nonlinear partial volume and aliasing artefacts

  20. Concept and development of measurement method of time sensitivity profile (TSP) in X-ray CT. Comparison of non-helical, single-slice helical, and multi-slice helical scans

    International Nuclear Information System (INIS)

    Tsujioka, Katsumi; Ida, Yoshihiro; Ohtsubo, Hironori; Takahashi, Yasukata; Niwa, Masayoshi

    2000-01-01

    We focused on the time element contained in a single CT image, and devised the concept of a time-sensitivity profile (TSP) describing how the time element is translated into an image. We calculated the data collection time range when the helical pitch is changed in non helical scans, single slice helical scans, and multi slice helical scans. We then calculated the time sensitivity profile (TSP) from the weighting applied when the data collection time range is translated into an image. TSP was also measured for each scanning method using our self-made moving phantom. TSPs obtained from the calculation and the experiments were very close. TSP showed interesting characteristics with each scanning method, especially in the case of multi slice helical scanning, in which TSP became shorter as helical pitch increased. We referred to the TSP's FWHM as the effective scanning time. When we conducted multi slice helical scanning at helical pitch 3, the effective scanning time increased to about 24% longer than that of a non helical scan. When we conducted multi slice helical scanning at helical pitch 5 or 6, the effective scanning time was about half that of a non helical scan. The time sensitivity profile (TSP) is a totally new concept that we consider an important element in discussing the time resolution of a CT scanner. The results of this review will provide significant data in determining the scanning parameters when scanning a moving object. (author)

  1. Three-dimensional CT endoscopic images of the larynx. Clinical application of helical CT

    International Nuclear Information System (INIS)

    Yumoto, Eiji; Sanuki, Tetsuji; Yasuhara, Yoshifumi; Ochi, Takashi

    1998-01-01

    Twenty-seven patients with several laryngeal ailments underwent helical computed tomography (CT) on 37 occasions. Ten of these 27 patients suffered from unilateral vocal fold paralysis (UVFP). Three-dimensional (3D) images of the laryngeal lumen viewed from various angles were produced for all sets of CT volumetric data, except for three which contained excessive motion artifacts. The present paper examined whether 3D endoscopic images could offer useful diagnostic and therapeutic information about UVFP. The 3D endoscopic images viewed from the tracheal side and the hemilaryngeal images viewed from the opposite side could delineate the vocal folds, ventricular fold and ventricle three-dimensionally. Atrophy and hypotonic changes to the vocal fold and expansion of the ventricle on the affected side were clearly shown. The 3D endoscopic images accurately showed the phonosurgical effects on the laryngeal structures. The 3D endoscopic images could be produced even when the vocal folds could not be observed with conventional endoscopy due to their overadduction. Multiplanar reconstruction (MPR) images in the coronal plane were reconstructed at a right angle to the glottic axis when the whole larynx was deviated. In addition, coronal MPR images showed a better resolution among the different layers of the vocal fold soft tissue than X-ray tomography. In conclusion, 3D endoscopic images combined with coronal MPR images can provide useful diagnostic an therapeutic information about UVFP, although motion artifacts may occur. (author)

  2. Thin section helical CT findings of klastskin tumor and benign stricture: cholangiographic correlation

    International Nuclear Information System (INIS)

    Choi, Guk Myeong; Han, Joon Koo; Kim, Tae Kyoung; Choi, Byung Ihn; Kim, Sun Whe; Cho, Yun Ku; Han, Man Chung; Yeon, Kyung Mo

    1997-01-01

    The purpose of this study was 1) to describe the thin section helical CT findings of hilar cholangiocarcinoma and of benign strcture, and to discuss the differential points between the two disease entities and 2) using cholangiographic correlation, to evaluate the diagnostic accuracy of helical CT in determining the extent of hilar cholangiocarcinoma. Twenty-seven patients with hilar cholangiocarcinoma and eight with benign biliary dilatation were studied. All except four with hilar cholangiocarcinoma, who underwentCT using a conventional scanner, were studied with two-phase helical CT. In all patients, cholangiographs were obtained by digital fluoroscopy after the injection of contrast materials into PTBD catheters. The level of obstruction was classified according to Bismuth, and 35 CT scans were studied blindly and retrospectively by two radiologists. The findings were analyzed for the presence of tumor, and then divided into two groups(cholangiocarcinomas and benign strictures), and the positive predictive value was calculated. The CT images of klatskin tumor were analyzed with special emphasis on the level and shape of the hilar obstruction. The level of biliary obstruction and extent of the tumor were carefully correlated with the results of cholangiography. Thin-section spiral CT correctly identified all tumor mass as a focal wall thickening obliterating the lumen. On arterial/portal phase CT scanning, 81% of infilterative tumors showed high attenuation. In all patients, differentiation between benign stricture and klaskin tumor was possible;correct identification of the level of obstruction and extent of tumor, according to Bismuth's classification, was possible in 63% of cases. For correct diagnosis of hilar cholangiocarcinoma and differentiation of benign stricture, helical CT was highly accurate and effective. Because of limital Z-axis resolution, however, the exact intraductal extent of the tumor was less accorately diagnosed.=20

  3. CT appearance of renal hemorrhage after extracorporeal shock wave lithotripsy

    Energy Technology Data Exchange (ETDEWEB)

    Kanazawa, Susumu; Araki, Toru; Takamoto, Hitoshi; Hata, Kazuhiro

    1988-07-01

    Computed Tomography (CT) was performed in three patients who were suspicious of renal hemorrhage after extracorporeal shock wave lithotripsy (ESWL). Post-ESWL scans demonstrated subcapsular hematoma in all three cases, and intrarenal hemorrhage in two cases, one of which had fluid collection in the pararenal space and hemorrhage in the posterior pararenal space on CT. Thickening of gerota fascia and bridging septa in the perirenal space was visualized on CT in all of them. CT demonstrated clearly the anatomic distribution and extent of renal hemorrhage, and it is important to comprehend the imaging anatomy of the perirenal area for CT evaluation.

  4. CT appearance of renal hemorrhage after extracorporeal shock wave lithotripsy

    International Nuclear Information System (INIS)

    Kanazawa, Susumu; Araki, Toru; Takamoto, Hitoshi; Hata, Kazuhiro

    1988-01-01

    Computed Tomography (CT) was performed in three patients who were suspicious of renal hemorrhage after extracorporeal shock wave lithotripsy (ESWL). Post-ESWL scans demonstrated subcapsular hematoma in all three cases, and intrarenal hemorrhage in two cases, one of which had fluid collection in the pararenal space and hemorrhage in the posterior pararenal space on CT. Thickening of gerota fascia and bridging septa in the perirenal space was visualized on CT in all of them. CT demonstrated clearly the anatomic distribution and extent of renal hemorrhage, and it is important to comprehend the imaging anatomy of the perirenal area for CT evaluation. (author)

  5. Intracranial tuberculosis in children: CT appearance and clinical outcome

    Energy Technology Data Exchange (ETDEWEB)

    Wallace, R C; Burton, E M; Gerald, B E [Le Bonheur Children' s Medical Center, Memphis, TN (United States). Dept. of Radiology Tennessee Univ., Memphis (United States); Barrett, F F; Leggiadro, R J [Le Bonheur Children' s Medical Center, Memphis, TN (United States). Dept. of Pediatrics Tennessee Univ., Memphis (United States); Lasater, O E [Le Bonheur Children' s Medical Center, Memphis, TN (United States). Dept. of Pathology Tennessee Univ., Memphis (United States)

    1991-05-01

    We retrospectively evaluated the CT studies of 9 children who presented with intracranial tuberculosis during 1981-1987, and compared their radiographic appearance with the clinical outcome. The most common radiographic findings were: 1) Ventriculomegaly (7/9), 2) tuberculoma formation (6/9), and 3) infarction (4/9). Of 7 patients with ventriculomegaly, 3 required a ventricular shunt and 2 had spontaenous resolution of ventricular dilatation. Four children with ventriculomegaly were moderately or severely retarded, one had cognitive dysfunction, and one was neurologically normal. Four of six children with tuberculoma also had infarction and/or ventriculomegaly; of these four children, three were moderately or severely retarded. Two patients with tuberculoma as the only intracranial abnormality had complete resolution or the granuloma with normal neurologic outcome following antituberculous therapy. The four children with large vessel infarction also had ventriculomegaly; three had poor clinical outcome. The presence of tuberculoma alone is not necessarily predictive of poor neurologic outcome; age less than 20 months, infarct, and/or ventriculomegaly are usually associated with sequelae. (orig.).

  6. Clinical Application of colored three-dimensional CT (3D-CT) for brain tumors using helical scanning CT (HES-CT)

    International Nuclear Information System (INIS)

    Ogura, Yuko; Katada, Kazuhiro; Fujisawa, Kazuhisa; Imai, Fumihiro; Kawase, Tsukasa; Kamei, Yoshifumi; Kanno, Tetsuo; Takeshita, Gen; Koga, Sukehiko

    1995-01-01

    We applied colored three-dimensional CT (colored 3D-CT) images to distinguish brain tumors from the surrounding vascular and bony structures using a work station system and helical scanning CT (HES-CT). CT scanners with a slip-ring system were employed (TCT-900S and X vigor). A slice thickness of 2 mm and bed speed of 2 mm/s were used. The volume of contrast medium injected was 60 to 70 ml. Four to 8 colors were used for the tissue segmentation on the workstation system (xtension) using the data transferred from HES-CT. Tissue segmentation succeeded on the colored 3D-CT images in all 13 cases. The relationship between the tumors and the surrounding structures were easily recognized. The technique was useful to simulate operative fields, because deep structures could be visualized by cutting and drilling the colored 3D-CT volumetric data. On the basis of our findings, we suggest that colored 3D-CT images should be used as a supplementary aid for preoperative simulation. (author)

  7. Adenocarcinoma of the pancreatic head: preoperative helical CT. Criteria of resectability

    International Nuclear Information System (INIS)

    Kozima, Shigeru; Szelagowski, Carlos; Tisserand, Guy L.; Ocampo, Carlos; Zandalazini, Hugo; Silva, Walter; Oria, Alejandro; Vidovic, Gustavo; Varas, Pablo

    2001-01-01

    Objective: The purpose of this study is to determine the accuracy of biphasic helical CT scanning in predicting resectability of adenocarcinoma of the head of the pancreas by staying tumor involvement of the portal and superior mesenteric veins. Material and methods: 46 patients with proven adenocarcinoma of the head of the pancreas who underwent curative or palliative surgery were studied with preoperative biphasic helical CT scanning. Tumor involvement of the portal and mesenteric veins was graduated on a 1-3 scale based on circumferential contiguity of the tumor vessel. Grade 1: without contact; grade 2: tumor involvement of less than 50% of the vessel; grade 3: tumor involvement of more than 50%. Results: The total number of vessels evaluated was 92. In our series the preoperative biphasic helical CT was accurate in 77% for resectability and unresectability. Conclusion: Our experience of staging in 3 grades with biphasic helical CT, vessel involvement the portal and superior mesenteric veins of adenocarcinoma of the head of the pancreas is highly specific for unresectable tumor in patients who were graded 2 and 3. (author)

  8. Current status of multi-detector row helical CT in imaging of adult ...

    African Journals Online (AJOL)

    Current status of multi-detector row helical CT in imaging of adult acquired pancreatic diseases and assessing surgical neoplastic resectability. ... The presence of inflammation, masses, and vascular invasion was evaluated and interpreted images were obtained during each phase. Results were compared with surgery, ...

  9. Usefulness of unenhanced helical CT in patients with suspected ureteral colic

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Bong Soo; Nam Kung, Sook; Kim, Heung Cheol; Hwang, Woo Chul; Lee, In Sun; Hwang, Im Kyung; Kim, Ho Chul; Bae, Sang Hoon; Lee, Sang Kon; Lee, Seong Ho [College of Medicine, Hallym Univ., Chunchon (Korea, Republic of)

    2002-07-01

    To determine the usefulness of unenhanced helical CT in patients with suspected renal colic. One hundred and fourteen patients with suspected ureteral colic, referred by physicians, underwent unenhanced helical CT. Two radiologists prospectively interpreted the results, determining the presence or absence of ureter stone and other diseases the arise outside the urinary tract. In cases of ureteral stone, we retrospectively sought secondary signs of hydronephrosis, perinephric fat stranding, thickening of renal fascia, renal enlargement, and the tissue rim sign. Among the 114 patients, 57 were confirmed as having ureter stones. Unenhanced helical CT depicted 57 of 58 stones in 57 patients, producing one false-negative and one false-positive result. Overall, the results showed 98% sensitivity, 95% specificity, 98% positive predictive value, 95% negative predictive value, and 97% accuracy. The frequencies of secondary signs were as follows: hydronephrosis, 95%(54/57); perinephric fat stranding, 81% (46/57); thickening of renal fascia, 77% (44/57); renal enlargement , 65%(37/57); and the tissure rim sign 72%(21/29). In 20 patients, the diagnoses were not related to stone disease and included one false-negative diagnosis of pyonephrosis. Unenhanced helical CT provides information which is valuable in the accurate diagnosis of ureteral stone as well as other diseases that arise outside the urinary tract in patients with suspected renal colic.

  10. Comparison of radiation dose estimates, image noise, and scan duration in pediatric body imaging for volumetric and helical modes on 320-detector CT and helical mode on 64-detector CT

    International Nuclear Information System (INIS)

    Johnston, Jennifer H.; Podberesky, Daniel J.; Larson, David B.; Alsip, Christopher; Yoshizumi, Terry T.; Angel, Erin; Barelli, Alessandra; Toncheva, Greta; Egelhoff, John C.; Anderson-Evans, Colin; Nguyen, Giao B.; Frush, Donald P.; Salisbury, Shelia R.

    2013-01-01

    Advanced multidetector CT systems facilitate volumetric image acquisition, which offers theoretic dose savings over helical acquisition with shorter scan times. Compare effective dose (ED), scan duration and image noise using 320- and 64-detector CT scanners in various acquisition modes for clinical chest, abdomen and pelvis protocols. ED and scan durations were determined for 64-detector helical, 160-detector helical and volume modes under chest, abdomen and pelvis protocols on 320-detector CT with adaptive collimation and 64-detector helical mode on 64-detector CT without adaptive collimation in a phantom representing a 5-year-old child. Noise was measured as standard deviation of Hounsfield units. Compared to 64-detector helical CT, all acquisition modes on 320-detector CT resulted in lower ED and scan durations. Dose savings were greater for chest (27-46%) than abdomen/pelvis (18-28%) and chest/abdomen/pelvis imaging (8-14%). Noise was similar across scanning modes, although some protocols on 320-detector CT produced slightly higher noise. Dose savings can be achieved for chest, abdomen/pelvis and chest/abdomen/pelvis examinations on 320-detector CT compared to helical acquisition on 64-detector CT, with shorter scan durations. Although noise differences between some modes reached statistical significance, this is of doubtful diagnostic significance and will be studied further in a clinical setting. (orig.)

  11. Non-contrast thin-section helical CT of urinary tract calculi in children

    International Nuclear Information System (INIS)

    Strouse, Peter J.; Bates, Gregory D.; Bloom, David A.; Goodsitt, Mitchell M.

    2002-01-01

    Background: Non-contrast thin-section helical CT has gained acceptance for the diagnosis of urinary tract calculi in adults, but experience with the technique in children is limited. Purpose: To evaluate the utility of non-contrast thin section helical CT for the diagnosis of urinary tract calculi in children. Materials and methods: Radiology databases at three pediatric institutions were searched to identify all pediatric patients evaluated by ''renal stone'' protocol CT scans (no oral or intravenous contrast, scans covering the entire urinary tract obtained in helical mode with narrow collimation (< 5 mm)). CT scans were reviewed for the primary finding of urinary tract calculi, for secondary signs of acute urinary tract obstruction and for evidence of alternative diagnoses. Medical records were reviewed to determine clinical presentation and to confirm the eventual diagnosis. Results: One hundred thirty-seven scans of 113 children (mean age: 11.2 years) were studied. Thirty-eight of 94 examinations (40%) performed on 82 children for acute pain and/or hematuria showed ureteral calculi. Alternative diagnoses were suggested by CT on 16 scans (17%). Twenty-eight scans were performed on 10 asymptomatic children with known calculus disease confirming renal stone burden on 21 scans (75%) and persistent ureteral calculi on 6 scans (21%). Upper tract calculi were demonstrated on 10 of 15 scans (67%) performed to evaluate for calculi in patients with known non-calculus genitourinary tract abnormalities. Conclusions: Non-contrast thin section helical CT is a useful method to diagnose urinary tract calculi in children. Radiation dose in this retrospective study may exceed the lowest possible radiation dose for diagnostic accuracy. Further research is needed to optimize CT imaging parameters, while maintaining diagnostic accuracy and minimizing radiation dose. (orig.)

  12. Patellofemoral joint dysfunction. Combined diagnostic imaging evaluation (X-rays, 3D helical CT and MRI)

    International Nuclear Information System (INIS)

    Carrascosa, P.; Sanchez, F.; Mazzucco, J.; Capanay, C.; Carrascosa, J.

    2000-01-01

    The comprehensive study including 3D helical CT, Magnetic Resonance (MR) and X-ray exams provide a more complete diagnosis than those obtained through the conventional CT. We studied 43 patients with presumptive or certain diagnosis of patellofemoral instability. All the patients were studied by: a) Radiological pair; b) Tomography under extension and flexion, without and with contraction, using a helical CT equipment; and c) MRI STIR sequence in axial plane. The findings were classified as muscular lesion, cartilage lesion, bone and associated lesions (e.g. synovitis), statistically comparing both studies (comprehensive vs. conventional). The results allow us to accept the hypothesis that the comprehensive study provides a more complete diagnosis about the origin of the patellofemoral dysfunction. In 65% of the patients, the conventional study gave a negative result. Only in 35% of the cases the result was positive, but incomplete, showing only 35.3% of the pathological findings detected by the comprehensive study. (author)

  13. Single-slice rebinning method for helical cone-beam CT

    International Nuclear Information System (INIS)

    Noo, F.; Defrise, M.; Clackdoyle, R.

    1999-01-01

    In this paper, we present reconstruction results from helical cone-beam CT data, obtained using a simple and fast algorithm, which we call the CB-SSRB algorithm. This algorithm combines the single-slice rebinning method of PET imaging with the weighting schemes of spiral CT algorithms. The reconstruction is approximate but can be performed using 2D multislice fan-beam filtered backprojection. The quality of the results is surprisingly good, and far exceeds what one might expect, even when the pitch of the helix is large. In particular, with this algorithm comparable quality is obtained using helical cone-beam data with a normalized pitch of 10 to that obtained using standard spiral CT reconstruction with a normalized pitch of 2. (author)

  14. Adrenal cavernous hemangioma: MRI, CT, and US appearance

    International Nuclear Information System (INIS)

    Marotti, M.; Sucic, Z.; Krolo, I.; Dimanovski, J.; Klaric, R.; Ferencic, Z.; Karapanda, N.; Babic, N.; Pavlekovic, K.

    1997-01-01

    Two cases of rare adrenal cavernous hemangiomas are reported, one imaged with conventional X-ray techniques, US, CT, and MRI, and the other with US and CT. The CT technique clearly demonstrated calcifications and the internal structure of the lesions in both cases and peripheral rim enhancement on the postcontrast scan in one patient. Although MRI demonstrated accurately the complex nature of the lesion, the inability to visualize the calcified areas do not allow to make a specific histologic diagnosis. (orig.). With 8 figs

  15. Vertical foramina in the lumbosacral region: CT appearance

    International Nuclear Information System (INIS)

    Beers, G.J.; Carter, A.P.; McNary, W.F.

    1984-01-01

    Several computed tomographic (CT) examples of vertically oriented foramina in the neural arches of the lumbosacral vertebrae are presented. The literature is reviewed briefly, and the possible clincal and embryologic significance of these foramina is discussed

  16. The usefulness of three-dimensional helical CT for the detection of abnormalities of the auditory ossicles

    International Nuclear Information System (INIS)

    Gong, Honghan; Hiraishi, Kumiko; Uesugi, Yasuo; Shimizu, Tadafumi; Narabayashi, Isamu

    1996-01-01

    To evaluate the usefulness of three-dimensional (3D) helical CT for the detection of abnormalities of the auditory ossicles, 3D helical CT of the middle ear was performed in seven patients with hearing disorder. It revealed that 4 patients had congenital deficiency of the auditory ossicles, 2 patients with chronic otitis media had shortening of the incus and one patient with head injury had doubtful fracture of the incus. This study indicated that 3D helical CT of the middle ear can represent the auditory ossicles objectively and can offer detailed diagnosis. (author)

  17. Optimization of pediatric examinations in a multislice helical CT

    International Nuclear Information System (INIS)

    Ombada, T. H. A.

    2010-12-01

    Radiological protection of pediatric patients undergoing medical imaging procedures involving ionizing radiation has always received special attention. This is due to the fact that children have higher radiation sensitivity and increased likelihood for radiation-induced cancer manifesting in many more years of their life than adults. In computed tomography (CT), such attention is more important because of the potential of relatively higher radiation doses during these procedures. Such high doses are possible with technological developments where volume scanning using faster multi-slice CT systems is now preferred to conventional CT equipment. The task of this study is to assess the optimization of paediatric doses in multi-slice CT examinations. It was carried out in Alrebat University Hospital for 31 pediatric patients, 43 examinations (27 head examination and 16 body (chest, abdomen and pelvis) examinations). Data were collected for scan parameters (kV, m As, pitch, scan length, number of slices and slice thickness) and doses displayed in monitor (CTDI v ol and DLP) for head examinations and body (chest, abdomen and pelvis) examinations. For head CT, displayed CTDI v ol ranged from 1.56 to 69.12 mGy, calculated value from 2.10 to 70.93 mGy. Displayed DLP ranged from 53 to 1817 mGy.cm, calculated from 95.30 to 1532.16 mGy. cm. For body examination, the range of displayed CTDI from 1.63 to 3.92 mGy, calculated value from 2.22 to 5.34 mGy. Displayed DLP ranged from 34 to 194 mGy.cm, for calculated from 45.89 to 161.98 mGy. cm. The calculated values are in agreement with reference study dose values although there are some high values in this study for some examinations, this variation or difference may attribute to variation in pediatric ages (9 days- 15 years), scan length and m As values. There is variation between calculated and displayed values. more optimization for CT doses is needed. (Author)

  18. Optimization of pediatric examinations in a multislice helical CT

    Energy Technology Data Exchange (ETDEWEB)

    Ombada, T H. A. [Atomic Energy Council, Sudan Academy of Sciences (SAS), Khartoum (Sudan)

    2010-12-15

    Radiological protection of pediatric patients undergoing medical imaging procedures involving ionizing radiation has always received special attention. This is due to the fact that children have higher radiation sensitivity and increased likelihood for radiation-induced cancer manifesting in many more years of their life than adults. In computed tomography (CT), such attention is more important because of the potential of relatively higher radiation doses during these procedures. Such high doses are possible with technological developments where volume scanning using faster multi-slice CT systems is now preferred to conventional CT equipment. The task of this study is to assess the optimization of paediatric doses in multi-slice CT examinations. It was carried out in Alrebat University Hospital for 31 pediatric patients, 43 examinations (27 head examination and 16 body (chest, abdomen and pelvis) examinations). Data were collected for scan parameters (kV, m As, pitch, scan length, number of slices and slice thickness) and doses displayed in monitor (CTDI{sub v}ol and DLP) for head examinations and body (chest, abdomen and pelvis) examinations. For head CT, displayed CTDI{sub v}ol ranged from 1.56 to 69.12 mGy, calculated value from 2.10 to 70.93 mGy. Displayed DLP ranged from 53 to 1817 mGy.cm, calculated from 95.30 to 1532.16 mGy. cm. For body examination, the range of displayed CTDI from 1.63 to 3.92 mGy, calculated value from 2.22 to 5.34 mGy. Displayed DLP ranged from 34 to 194 mGy.cm, for calculated from 45.89 to 161.98 mGy. cm. The calculated values are in agreement with reference study dose values although there are some high values in this study for some examinations, this variation or difference may attribute to variation in pediatric ages (9 days- 15 years), scan length and m As values. There is variation between calculated and displayed values. more optimization for CT doses is needed. (Author)

  19. Acute ureterolithiasis: Incidence of secondary signs on unenhanced helical CT and influence on patient management

    Energy Technology Data Exchange (ETDEWEB)

    Ege, G. E-mail: gurkanege@yahoo.com; Akman, H.; Kuzucu, K.; Yildiz, S

    2003-12-01

    AIM: The purpose of this study was to determine the incidence of secondary signs associated with ureteral stones on unenhanced helical computed tomography (CT) of patients with acute renal colic, and to correlate these with patient management and outcome. MATERIALS AND METHODS: One hundred and ten patients with ureterolithiasis were evaluated prospectively for the secondary signs of obstruction on unenhanced helical CT. Our attention was focused primarily on the presence or absence of seven secondary signs on unenhanced helical CT, including hydronephrosis, unilateral renal enlargement, perinephric oedema, unilateral absence of the white pyramid, hydroureter, periureteral oedema and lateroconal fascial thickening. RESULTS: Of the 110 patients, 91 (82.7%) had hydroureter, 88 (80%) had hydronephrosis, 65 (59%) had periureteric oedema and 63 (57.2%) had unilateral renal enlargement. Ninety stones passed spontaneously and 21 required intervention. CONCLUSION: Secondary signs of urinary tract obstruction are useful and supportive findings in interpretation of the CT examination. In our experience, the most reliable signs indicating ureteral obstruction are hydroureter, hydronephrosis, periureteral oedema and unilateral renal enlargement, respectively. In addition, stones larger than 6 mm, located within the proximal two thirds of the ureter, and seen associated with five or more the secondary signs of obstruction, are more likely to require endoscopic removal and/or lithotripsy.

  20. Efficacy of helical CT in evaluating local tumor extent of breast cancer

    International Nuclear Information System (INIS)

    Ozaki, Yutaka

    2001-01-01

    The purpose of this study is to clarify the diagnostic accuracy of helical CT (HCT) in the determination of local tumor extent of breast cancer. One hundred forty consecutive patients with breast cancer, including 87 invasive ductal carcinomas without extensive intraductal components (EIC), 44 invasive ductal carcinomas with EIC, 2 non-invasive ductal carcinomas, and 7 invasive lobular carcinomas, were included in the study. Three-dimensional tumor diameter including whole extent was measured on HCT, and the amount of invasion to fat tissue, skin, pectoral muscle, and chest wall was estimated using a three-step scale. These results were then compared with the pathological findings. Breast cancers appeared as areas of high attenuation compared with the surrounding breast tissue in all patients. Tumor extent was correctly diagnosed by HCT to within a maximum difference of 1 cm in 88 patients (63%) and within 2 cm in 122 patients (87%). Sensitivity, specificity, and accuracy in diagnosing muscular invasion of breast cancer using HCT were 100%, 99%, and 99%, respectively. Sensitivity, specificity, and accuracy in diagnosing skin invasion of breast cancer using HCT were 84%, 93%, and 91%, respectively. HCT was able to visualize all of the tumors and detect the correct tumor extent in most patients. (author)

  1. Efficacy of helical CT in evaluating local tumor extent of breast cancer

    Energy Technology Data Exchange (ETDEWEB)

    Ozaki, Yutaka [Juntendo Univ., Chiba (Japan). Urayasu Hospital

    2001-04-01

    The purpose of this study is to clarify the diagnostic accuracy of helical CT (HCT) in the determination of local tumor extent of breast cancer. One hundred forty consecutive patients with breast cancer, including 87 invasive ductal carcinomas without extensive intraductal components (EIC), 44 invasive ductal carcinomas with EIC, 2 non-invasive ductal carcinomas, and 7 invasive lobular carcinomas, were included in the study. Three-dimensional tumor diameter including whole extent was measured on HCT, and the amount of invasion to fat tissue, skin, pectoral muscle, and chest wall was estimated using a three-step scale. These results were then compared with the pathological findings. Breast cancers appeared as areas of high attenuation compared with the surrounding breast tissue in all patients. Tumor extent was correctly diagnosed by HCT to within a maximum difference of 1 cm in 88 patients (63%) and within 2 cm in 122 patients (87%). Sensitivity, specificity, and accuracy in diagnosing muscular invasion of breast cancer using HCT were 100%, 99%, and 99%, respectively. Sensitivity, specificity, and accuracy in diagnosing skin invasion of breast cancer using HCT were 84%, 93%, and 91%, respectively. HCT was able to visualize all of the tumors and detect the correct tumor extent in most patients. (author)

  2. The appearance and effects of metallic implants in CT images

    International Nuclear Information System (INIS)

    Kairn, T.; Crowe, S.B.; Trapp, J.V.; Fogg, P.

    2013-01-01

    The computed tomography (CT) imaging artefacts that metallic medical implants produce in surrounding tissues are usually contoured and over-ridden during radiotherapy treatment planning. In cases where radiotherapy treatment beams unavoidably pass though implants, it is especially important to understand the imaging artefacts that may occur within the implants themselves. This study examines CT images of a set of simple metallic objects, immersed in water, in order to evaluate reliability and variability of CT numbers (Hounsfield units, HUs) within medical implants. Model implants with a range of sizes (heights from 2.2 to 49.6 mm), electron densities (from 2.3 to 7.7 times the electron density of water) and effective atomic numbers (from 3.9 to 9.0 times the effective atomic number of water in a CT X-ray beam) were created by stacking metal coins from several currencies. These 'implants' were CT scanned within a large (31.0 cm across) and a small (12.8 cm across) water phantom. Resulting HU values are as much as 50 % lower than the result of extrapolating standard electron density calibration data (obtained for tissue and bone densities) up to the metal densities and there is a 6 % difference between the results obtained by scanning with 120 and 140 kVp tube potentials. Profiles through the implants show localised cupping artefacts, within the implants, as well as a gradual decline in HU outside the implants that can cause the implants' sizes to be over estimated by 1.3–9.0 mm. These effects are exacerbated when the implants are scanned in the small phantom or at the side of the large phantom, due to reduced pre-hardening of the X-ray beam in these configurations. These results demonstrate the necessity of over-riding the densities of metallic implants, as well as their artefacts in tissue, in order to obtain accurate radiotherapy dose calculations.

  3. The appearance and effects of metallic implants in CT images.

    Science.gov (United States)

    Kairn, T; Crowe, S B; Fogg, P; Trapp, J V

    2013-06-01

    The computed tomography (CT) imaging artefacts that metallic medical implants produce in surrounding tissues are usually contoured and over-ridden during radiotherapy treatment planning. In cases where radiotherapy treatment beams unavoidably pass though implants, it is especially important to understand the imaging artefacts that may occur within the implants themselves. This study examines CT images of a set of simple metallic objects, immersed in water, in order to evaluate reliability and variability of CT numbers (Hounsfield units, HUs) within medical implants. Model implants with a range of sizes (heights from 2.2 to 49.6 mm), electron densities (from 2.3 to 7.7 times the electron density of water) and effective atomic numbers (from 3.9 to 9.0 times the effective atomic number of water in a CT X-ray beam) were created by stacking metal coins from several currencies. These 'implants' were CT scanned within a large (31.0 cm across) and a small (12.8 cm across) water phantom. Resulting HU values are as much as 50 % lower than the result of extrapolating standard electron density calibration data (obtained for tissue and bone densities) up to the metal densities and there is a 6 % difference between the results obtained by scanning with 120 and 140 kVp tube potentials. Profiles through the implants show localised cupping artefacts, within the implants, as well as a gradual decline in HU outside the implants that can cause the implants' sizes to be over estimated by 1.3-9.0 mm. These effects are exacerbated when the implants are scanned in the small phantom or at the side of the large phantom, due to reduced pre-hardening of the X-ray beam in these configurations. These results demonstrate the necessity of over-riding the densities of metallic implants, as well as their artefacts in tissue, in order to obtain accurate radiotherapy dose calculations.

  4. Technical evaluation of DIC helical CT and 3D image for laparoscopic cholecystectomy

    International Nuclear Information System (INIS)

    Shibuya, Kouki; Uchimura, Fumiaki; Haga, Tomo

    1995-01-01

    Recently Laparoscopic Cholecystectomy (L.C.) was widely accepted for its low invasive procedure. Before L.C., it is important to understand anatomical recognization of biliary tree. We examined DIC Helical CT before L.C., and reconstructed 3D Cholangiographic image. We evaluated physical potentiality of Helical CT using Section Sensitivity Profiles (SSP) with 5, 10 mm slice thickness on 360deg linear interpolation. And we analyzed most useful 3D image for biliary tree. Results showed the SSP depended on slice thickness (X-ray beam width) and table movement at same reconstruction spacing. The peak of SSP depended on slice thickness (X-ray beam width) and reconstruction spacing at same table movement. Clinically, it was necessary under 5 mm/rotation table movement and 5 mm thickness for acquiring volume image data. 3D Cholangiographic image reconstructed with 1 mm spacing image was useful in evaluation of relationship of anatomical biliary tree. (author)

  5. Acquiring 4D thoracic CT scans using a multislice helical method

    International Nuclear Information System (INIS)

    Keall, P J; Starkschall, G; Shukla, H; Forster, K M; Ortiz, V; Stevens, C W; Vedam, S S; George, R; Guerrero, T; Mohan, R

    2004-01-01

    Respiratory motion degrades anatomic position reproducibility during imaging, necessitates larger margins during radiotherapy planning and causes errors during radiation delivery. Computed tomography (CT) scans acquired synchronously with the respiratory signal can be used to reconstruct 4D CT scans, which can be employed for 4D treatment planning to explicitly account for respiratory motion. The aim of this research was to develop, test and clinically implement a method to acquire 4D thoracic CT scans using a multislice helical method. A commercial position-monitoring system used for respiratory-gated radiotherapy was interfaced with a third generation multislice scanner. 4D cardiac reconstruction methods were modified to allow 4D thoracic CT acquisition. The technique was tested on a phantom under different conditions: stationary, periodic motion and non-periodic motion. 4D CT was also implemented for a lung cancer patient with audio-visual breathing coaching. For all cases, 4D CT images were successfully acquired from eight discrete breathing phases, however, some limitations of the system in terms of respiration reproducibility and breathing period relative to scanner settings were evident. Lung mass for the 4D CT patient scan was reproducible to within 2.1% over the eight phases, though the lung volume changed by 20% between end inspiration and end expiration (870 cm 3 ). 4D CT can be used for 4D radiotherapy, respiration-gated radiotherapy, 'slow' CT acquisition and tumour motion studies

  6. CT appearance of liver and gallbladder in type II diabetics

    International Nuclear Information System (INIS)

    Li Jingshan; Li Wei; Zhang Yuzhong; Zhao Xiuyi; Zhang Xuelin

    2005-01-01

    Objective: To evaluate CT findings of liver and gallbladder in type II diabetics and to discuss diabetic, and investigate the correlation between type II diabetics, and investigate the correlation between the diabetes and the lesions found in the liver or gallbladder. Methods: Retrospective analysis was made on the CT findings of hepatic and gallbladder lesions in 586 cases of II diabetes. Results: In total 586 type II diabetics, cholecystitis and/or gallstone were revealed in 33.45% patients; and hepatic alteration was noted in 20.48% cases. Hepatic abnormalities were found in 58.67% cases in the cholecystitis/gallstone group, significantly different from the group with unremarkable gallbladder, in which hepatic lesions were found only in 1.28% cases. Conclusion: The hepatic alteration is secondary to the gallbladder lesions in type II diabetics. (authors)

  7. Assessment of hepatic arterial variation using multidetector helical CT-angiography

    International Nuclear Information System (INIS)

    Lee, Dong Hoon; Lee, Jun Woo; Jun, Woong Bae; Lee, Suk Hong

    2001-01-01

    To evaluate the anatomy of the hepatic artery and normal variants using oblique thick-slab maximal intensity projection (MIP) 3-D CT angiography and multidetector helical CT technology. In 70 patients, axial three-phase CT together with multidetector helical CT and a nonionic contrast agent was used to evaluate liver disease. During the early arterial phase, the parameters were as follow: slice thickness, 2.5 mm; table speed, 15 mm/rotation, pitch, 6; contrast material, 4 ml/sec; total 120 ml. Using the MIP technique and an Advantage window voxtal 3.03 system (GE), the images obtained were reconstructed as 3D angiograms. In each case, the arterial anatomy and its variants were recorded. A typical anatomy was found in 53 cases (75.7%). Common variants were a left hepatic artery arising from the left gastric artery(8 cases, 11.4 %) and a right hepatic artery arising from the superior mesenteric artery(3 cases, 4.3%). Other variant cases were right hepatic artery arising from the gastroduodenal artery(2 cases, 2.9%), a proper hepatic artery arising from the left gastric artery (1 case, 1.4%), a hepatomesenteric trunk (1 case), a hepatogastric/splenomesenteric trunk(1 case), and a celiomesenteric trunk (1 case). 3-D hepatic angiography using multidetector helical CT technology is non-invasive and as accurate as conventional angiography for the evaluation of hepatic arterial anatomy. It is thus considered that 3-D CT angiography is very helpful for the evaluation of hepatic arterial anatomy prior to liver surgery such as transplantation or the treatment of hepatocellular carinoma

  8. The helical three-dimensional CT in the diagnosis of torticollis with occipitocondylar hypoplasia

    International Nuclear Information System (INIS)

    Ilkko, E.; Tikkakoski, T.; Pyhtinen, J.

    1998-01-01

    Congenital anomalies of the atlanto-occipital and atlantoaxial joints are rare. Those most commonly reported are atlantoaxial instability, basilar impression, anomalies of the odontoid process, laxity of the transverse atlantal ligament and atlanto-occipital fusion. Occipital condylar hypoplasia is infrequent and difficult to recognise. We recently diagnosed it using helical 3D CT in association with torticollis in two patients. The first patient had a several year history of torticollis. The second patient had acute cervical lymphadenitis associated with post-operative torticollis. 3D CT distinctly revealed atlantoaxial subluxation with hypoplasia of the occipital condyles in both cases. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)

  9. The helical three-dimensional CT in the diagnosis of torticollis with occipitocondylar hypoplasia

    International Nuclear Information System (INIS)

    Ilkko, E.; Tikkakoski, T.; Pyhtinen, J.

    1998-01-01

    Congenital anomalies of the atlanto-occipital and atlantoaxial joints are rare. Those most commonly reported are atlantoaxial instability, basilar impression, anomalies of the odontoid process, laxity of the transverse atlantal ligament and atlanto-occipital fusion. Occipital condylar hypoplasia is infrequent and difficult to recognise. We recently diagnosed it using helical 3D CT in association with torticollis in two patients. The first patient had a several year history of torticollis. The second patient had acute cervical lymphadenitis associated with post-operative torticollis. 3D CT distinctly revealed atlantoaxial subluxation with hypoplasia of the occipital condyles in both cases

  10. Preliminary study on helical CT algorithms for patient motion estimation and compensation

    International Nuclear Information System (INIS)

    Wang, G.; Vannier, M.W.

    1995-01-01

    Helical computed tomography (helical/spiral CT) has replaced conventional CT in many clinical applications. In current helical CT, a patient is assumed to be rigid and motionless during scanning and planar projection sets are produced from raw data via longitudinal interpolation. However, rigid patient motion is a problem in some cases (such as in the skull base and temporal bone imaging). Motion artifacts thus generated in reconstructed images can prevent accurate diagnosis. Modeling a uniform translational movement, the authors address how patient motion is ascertained and how it may be compensated. First, mismatch between adjacent fan-beam projections of the same orientation is determined via classical correlation, which is approximately proportional to the patient displacement projected onto an axis orthogonal to the central ray of the involved fan-beam. Then, the patient motion vector (the patient displacement per gantry rotation) is estimated from its projections using a least-square-root method. To suppress motion artifacts, adaptive interpolation algorithms are developed that synthesize full-scan and half-scan planar projection data sets, respectively. In the adaptive scheme, the interpolation is performed along inclined paths dependent upon the patient motion vector. The simulation results show that the patient motion vector can be accurately and reliably estimated using their correlation and least-square-root algorithm, patient motion artifacts can be effectively suppressed via adaptive interpolation, and adaptive half-scan interpolation is advantageous compared with its full-scale counterpart in terms of high contrast image resolution

  11. Clinical application of helical CT 3D reconstruction for the dental orthopaedics

    International Nuclear Information System (INIS)

    Han Benyi; Jiang Xiaolu; Li Hongru

    2005-01-01

    Objective: To evaluate the clinical application of helical CT 3D reconstruction technique in the dental orthopaedics. Methods: The helical CT was performed with 3.0 mm slice thickness and 1.0 pitch in 41 patients with dental orthopaedics. The 3D reconstructions, including maximum intensity projection (MIP), surface shaded display (SSD), and multiplanar reconstructions (MPR), were made for all the cases. Results: Thirty-seven of the 41 patients showed malalignment, tilt, rotation, overlap of the teeth and the different space between the longitudinal axes of the teeth. Twenty-five cases of them have shown 36 buried teeth in all. The axial images covered all the information. SSD demonstrated the external contours and entire morphologies of the teeth and the mandible with the relationship of the teeth alignment and the mandible. MIP clearly manifested the full view and the longitudinal alignment of the teeth. Among the 36 buried teeth, there were 29 palatally and 7 labially presented teeth, and they were morphologically delineated on MIP through various angles. Conclusion: The helical CT 3D reconstruction is a new technique to display the stereoscopic configuration of teeth. The combination of axial images and MIP, SSD, and MPR provides valuable anatomic and diagnostic information helpful for the surgeons to structure and determine the treatment protocol for the dental orthopaedics. (authors)

  12. Evaluation of coronary artery disease by helical CT using retrospective ECG-gating

    International Nuclear Information System (INIS)

    Kawawa, Yoko

    2001-01-01

    The purpose of this study is to evaluate the usefulness of helical CT using retrospective ECG-gating for visualization of the coronary artery and detection of coronary artery disease. We performed a coronary artery phantom study and established this new application, with 1-mm collimation, 1-mm table increment, and 0.1-mm reconstruction (0.8 sec/rotation). Helical CT of 31 patients with 39 coronary artery diseases (34 coronary artery stenoses, 1 vasospastic angina, 1 coronary artery dissection, 1 coronary artery ectasia and 2 coronary artery aneurysms) was performed in a single breath hold and ECG-gating without and with intravenous injection of nonionic iodine contrast material. We selected the images which were not affected by cardiac motion from the reconstruction images, in order to visualize the coronary artery for detection of coronary artery disease. The coronary artery was well visualized in 32 out of 39 vessels (82%). A good visualization of the coronary artery was correlated with the heart rate. Further, in this well visualized group, coronary artery diseases were detected in 24 out of 31 cases (77%). One case of vasospastic angina was not included. It was difficult to detect coronary artery disease in cases of heavily calcified vessels or in the left circumflex artery. Helical CT using this retrospective ECG-gating is a useful noninvasive examination for evaluation of coronary artery disease. (author)

  13. Measurement of MV CT dose index for Hi-ART helical tomotherapy unit

    International Nuclear Information System (INIS)

    Wang Yunlai; Liao Xiongfei

    2010-01-01

    Objective: To evaluate the patient dose from Hi-ART MV helical CT imaging in image-guided radiotherapy. Methods: Weighted CT dose index (CTDI W ) was measured with PTW TM30009 CT ion chamber in head and body phantoms, respectively,for slice thicknesses of 2, 4, 6 mm with scanned range of 5 cm and 15 cm. Dose length products (DLP) were subsequently calculated. The CTDI W and DLP were compared with XVI kV CBCT and ACQSim simulator CT for routine clinical protocols. Results: An inverse relationship between CTDI and the slice thickness was found. The dose distribution was inhomogeneous owing to the attenuation of the couch. CTDI and DLP had close relationship with the slice thickness and the scanned range. Patient dose from MVCT was lower than XVI CBCT for head, but larger for body scan. Conclusions: CTDI W can be used to assess the patient dose in MV helical CT due to its simplicity for measurement and reproducibility. Regular measurement should be performed in QA and QC program. Appropriate slice thickness and scan range should be chosen to reduce the patient dose. (authors)

  14. Emergencies in the retroperitoneum: assessment of spread of disease by helical CT

    Energy Technology Data Exchange (ETDEWEB)

    Scialpi, M. E-mail: michelescialpi@libero.it; Scaglione, M.; Angelelli, G.; Lupattelli, L.; Resta, M.C.; Resta, M.; Rotondo, A

    2004-04-01

    Acute pancreatitis, leaking abdominal aortic aneurysm, and renal trauma frequently occur in the setting of patients with abdominal nontraumatic and traumatic injury; it represents the most urgent conditions that may determine the presence of fluid collections or haematoma in the retroperitoneum. Single spiral CT and multidetector-row CT (MDCT) play an important role in diagnosis of retroperitoneal emergencies, providing useful informations on the type, site, extent and management of the fluid collections. An accurate CT assessment requires the awareness of the existence of dissectable retroperitoneal fascial planes. Fluid collections or haematoma tends to escape the retroperitoneal site of origin into planes extend from the diaphragm to the pelvic floor. We assess the multicompartimental anatomy of the retroperitoneum and the pathway of spread of the most frequent retroperitoneal fluid collections or haematoma by helical CT.

  15. The CT appearances of sclerosing mesenteritis and associated diseases

    International Nuclear Information System (INIS)

    Wat, S.Y.J.; Harish, S.; Winterbottom, A.; Choudhary, A.K.; Freeman, A.H.

    2006-01-01

    Sclerosing mesenteritis is characterized by non-specific inflammation of the mesenteric fat associated with variable amount of fibrosis. The aetiology is unclear; the pathogenesis is obscure, and even its nomenclature remains variable. It is a rare condition with imaging features that can be mistaken either for a mesenteric neoplasm or for a wide variety of non-neoplastic inflammatory conditions. Knowledge of the imaging features of this condition may prevent unwarranted aggressive therapy. This review discusses the pathogenesis, clinical manifestations of this condition, as well as illustrating the characteristic computed tomography (CT) features of sclerosing mesenteritis. A rational approach to the differential diagnosis is discussed

  16. Proton MRI appearance of cystic fibrosis: Comparison to CT

    International Nuclear Information System (INIS)

    Puderbach, Michael; Eichinger, Monika; Kauczor, Hans-Ulrich; Gahr, Julie; Mueller, Frank-Michael; Ley, Sebastian; Tuengerthal, Siegfried; Schmaehl, Astrid; Fink, Christian; Plathow, Christian; Wiebel, Matthias

    2007-01-01

    Cystic fibrosis (CF) is the most frequent inherited disorder leading to premature death in the Caucasian population. As life expectancy is limited by pulmonary complications, repeated imaging [chest X-ray, multislice high-resolution computed tomography (MS-HRCT)] is required in the follow-up. Magnetic resonance imaging (MRI) of the lung parenchyma is a promising new diagnostic tool. Its value for imaging lung changes caused by CF compared with CT is demonstrated. MRI performs well when compared with CT, which serves as the gold standard. Its lack in spatial resolution is obvious, but advantages in contrast and functional assessment compensate for this limitation. Thus, MRI is a reasonable alternative for imaging the CF lung and should be introduced as a radiation-free modality for follow-up studies in CF patients. For further evaluation of the impact of MRI, systematic studies comparing MRI and conventional imaging modalities are necessary. Furthermore, the value of the additional functional MRI (fMRI) information has to be studied, and a scoring system for the morphological and functional aspect of MRI has to be established. (orig.)

  17. Helical CT for lung-cancer screening. 3. Fundamental study for ultra-low-dose CT by application of small tube current and filter

    International Nuclear Information System (INIS)

    Itoh, Shigeki; Koyama, Shuji; Tusaka, Masatoshi; Maekoshi, Hisashi; Satake, Hiroko; Ishigaki, Takeo.

    1996-01-01

    In order to develop ultra-low-dose helical CT for lung cancer screening, the effect of reduction of the tube current to 20 mA and application of a 10 mm thick aluminium filter upon radiation dose and image quality was evaluated with a phantom. Exposure dose at the center of a gantry and absorbed dose at the center of an acrylic phantom at 20 mA with the filter were 15% and 29% of the dose at 50 mA without the filter, respectively. For reduction of absorbed dose, reduction of the tube current was more useful than application of the filter. Image noise at 20 mA with the filter was double that at 50 mA without the filter. Neither reduction of the tube current nor application of the filter changed full width at half maximum on section sensitivity of the Z-axis. Although reduction of the tube current did not affect the difference in CT values between an acrylic sphere and styroform, application of the filter caused a reduction of 4.5% in the difference in CT values. Neither reduction of the tube current nor application of the filter affected the contrast resolution of the high-contrast phantom; however, that of the low-contrast phantom deteriorated. Although improvement of the filter and evaluation of clinical images are necessary, reduction of the tube current to 20 mA and application of the aluminium filter appear to be a promising method for ultra-low-dose helical CT of the lung. (author)

  18. Peripancreatic vascular abnormalities complicating acute pancreatitis: contrast-enhanced helical CT findings

    International Nuclear Information System (INIS)

    Mortele, Koenraad J.; Mergo, Patricia J.; Taylor, Helena M.; Wiesner, Walter; Cantisani, Vito; Ernst, Michael D.; Kalantari, Babak N.; Ros, Pablo R.

    2004-01-01

    Objective: To determine the prevalence and morphologic helical computed tomography (CT) features of peripancreatic vascular abnormalities in patients with acute pancreatic inflammatory disease in correlation with the severity of the pancreatitis. Materials and methods: One hundred and fifty-nine contrast-enhanced helical CT scans of 100 consecutive patients with acute pancreatitis were retrospectively and independently reviewed by three observers. CT scans were scored using the CT severity index (CTSI): pancreatitis was graded as mild (0-2 points), moderate (3-6 points), and severe (7-10 points). Interobserver agreement for both the CT severity index and the presence of peripancreatic vascular abnormalities was calculated (K-statistic). Correlation between the prevalence of complications and the degree of pancreatitis was estimated using Fisher's exact test. Results: The severity of pancreatitis was graded as mild (n=59 scans), moderate (n=82 scans), and severe (n=18 scans). Venous abnormalities detected included splenic vein (SV) thrombosis (31 scans, 19 patients), superior mesenteric vein (SMV) thrombosis (20 scans, 14 patients), and portal vein (PV) thrombosis (17 scans, 13 patients). Arterial hemorrhage occurred in five patients (6 scans). In our series, no cases of arterial pseudoaneurysm formation were detected. The interobserver agreement range for scoring the degree of pancreatitis and the overall presence of major vascular abnormalities was 75.5-79.2 and 86.2-98.8%, respectively. The presence of the vascular abnormalities in correlation with the severity of pancreatitis was variable. Conclusion: Vascular abnormalities are relatively common CT findings in association with acute pancreatitis. The CT severity index is insufficiently accurate in predicting some of these complications since no statistically significant correlation between their prevalence and the severity of pancreatitis could be established

  19. CT portography by multidetector helical CT. Comparison of three rendering models

    International Nuclear Information System (INIS)

    Nakayama, Yoshiharu; Imuta, Masanori; Funama, Yoshinori; Kadota, Masataka; Utsunomiya, Daisuke; Shiraishi, Shinya; Hayashida, Yoshiko; Yamashita, Yasuyuki

    2002-01-01

    The purpose of this study was to assess the value of multidetector CT portography in visualizing varices and portosystemic collaterals in comparison with conventional portography, and to compare the visualizations obtained by three rendering models (volume rendering, VR; minimum intensity projection, MIP; and shaded surface display, SSD). A total of 46 patients with portal hypertension were examined by CT and conventional portography for evaluation of portosystemic collaterals. CT portography was performed by multidetector CT (MD-CT) scanner with a slice thickness of 2.5 mm and table feed of 7.5 mm. Three types of CT portographic models were generated and compared with transarterial portography. Among 46 patients, 48 collaterals were identified on CT transverse images, while 38 collaterals were detected on transarterial portography. Forty-four of 48 collaterals identified on CT transverse images were visualized with the MIP model, while 34 and 29 collaterals were visualized by the VR and SSD methods, respectively. The average CT value for the portal vein and varices was 198 HU with data acquisition of 50 sec after contrast material injection. CT portography by multidetector CT provides excellent images in the visualization of portosystemic collaterals. The images of collaterals produced by MD-CT are superior to those of transarterial portography. Among the three rendering techniques, MIP provides the best visualization of portosystemic collaterals. (author)

  20. CT portography by multidetector helical CT. Comparison of three rendering models

    Energy Technology Data Exchange (ETDEWEB)

    Nakayama, Yoshiharu; Imuta, Masanori; Funama, Yoshinori; Kadota, Masataka; Utsunomiya, Daisuke; Shiraishi, Shinya; Hayashida, Yoshiko; Yamashita, Yasuyuki [Kumamoto Univ. (Japan). School of Medicine

    2002-12-01

    The purpose of this study was to assess the value of multidetector CT portography in visualizing varices and portosystemic collaterals in comparison with conventional portography, and to compare the visualizations obtained by three rendering models (volume rendering, VR; minimum intensity projection, MIP; and shaded surface display, SSD). A total of 46 patients with portal hypertension were examined by CT and conventional portography for evaluation of portosystemic collaterals. CT portography was performed by multidetector CT (MD-CT) scanner with a slice thickness of 2.5 mm and table feed of 7.5 mm. Three types of CT portographic models were generated and compared with transarterial portography. Among 46 patients, 48 collaterals were identified on CT transverse images, while 38 collaterals were detected on transarterial portography. Forty-four of 48 collaterals identified on CT transverse images were visualized with the MIP model, while 34 and 29 collaterals were visualized by the VR and SSD methods, respectively. The average CT value for the portal vein and varices was 198 HU with data acquisition of 50 sec after contrast material injection. CT portography by multidetector CT provides excellent images in the visualization of portosystemic collaterals. The images of collaterals produced by MD-CT are superior to those of transarterial portography. Among the three rendering techniques, MIP provides the best visualization of portosystemic collaterals. (author)

  1. Determination of optimal parameters for three-dimensional reconstruction images of central airways using helical CT

    International Nuclear Information System (INIS)

    Hirose, Takahumi; Akata, Soichi; Matsuno, Naoto; Nagao, Takeshi; Abe, Kimihiko

    2002-01-01

    Three-dimensional (3D) image reconstruction of central airways using helical CT requires several user-defined parameters that exceed the requirements of conventional CT. The purpose of this study was to evaluate the optimal parameters for 3D images of central airways using helical CT. In our experimental study using a piglet immediately after sacrifice, 3D images of the central airway were evaluated with changes of 3D imaging parameters, such as detector collimation (1, 2, 3 and 6 mm), table speed (1, 2, 3 and 5 mm/sec), tube electric current (50, 100, 150, 200 and 250 mA), reconstruction interval (0.3, 0.5, 1, 2 and 3 mm), algorithm (mediastinum and lung) and interpolation method (180 deg and 360 deg). To minimize detector collimation, table speed, and reconstruction interval could provide the best 3D images of the central airway. Stair-step artifacts could also be reduced with a slow table speed. However, decreasing the collimation and table speed decreases not only the effective section thickness but also the scan coverage that can be achieved with a helical CT. For routine diagnosis, we conclude that optimal parameters for 3D images of the central airway are to minimize the table speed necessary to cover the volume of interest and to set detector collimation to 1/2 of the table speed. The reconstruction intervals should also be selected at up to 1/2 of the detector collimation, but with trade-offs of increased image processing time, data storage requirements, and physician time for image review. Regarding to tube electric current, 200 mA or more was necessary. Pixel noise increased with the algorithm for the lung. The 180 deg interpolation is better than 360 deg interpolation due to thin effective section thickness. (author)

  2. Multidetector-row helical CT: analysis of time management and workflow

    Energy Technology Data Exchange (ETDEWEB)

    Roos, Justus E.; Desbiolles, Lotus M.; Willmann, Juergen K.; Weishaupt, Dominik; Marincek, Borut; Hilfiker, Paul R. [Institute of Diagnostic Radiology, University Hospital Zurich (Switzerland)

    2002-03-01

    The purpose of this study was to evaluate time management and workflow for multidetector-row helical CT (MDCT). Time for patient and data handling of at total of 580 patients were evaluated at two different time periods (December 1999, August 2000), each for the following baseline measurements: (a) change of clothes/instruction; (b) patient placement on the CT table/i.v. catheter; (c) CT planning and programming; (d) CT data acquisition; (e) CT data reconstruction; (f) CT data storage/printing. All imaging was performed on a Somatom Volume Zoom (Siemens, Erlangen, Germany). Time measurements summarized for different CT protocols revealed the following: (a) 5:01 min ({+-}2.06 min); (b) 4:36 min ({+-}2.43 min); (c) 4:11 min ({+-}2.55 min); (d) 0:43 min ({+-}0.15 min); (e) 6:59 min ({+-}2.39 min); (f) 09:51 min ({+-}3.51 min). Planning and programming was most time-consuming for CT angiography, whereas chest and abdominal CT needed only 3:26 and 3:30 min, respectively. Reconstruction time was highest for HRCT (9:22 min) and CTA (9:03 min). Data storage/printing was most time-consuming for HRCT (13:02 min), followed by combined neck-chest-abdomen examinations (12:19 min). Comparing the two time periods, during which a software update was performed, a mean time reduction of 4:31 min per patient (15%, p<0.001) was achieved. Whereas CT data acquisition time is no longer a problem with MDCT, patient management, data reconstruction, and data storage are the most time-consuming parts. Well-trained technicians, state-of-the-art workstations, and fast networking are the most important factors to improve workflow. (orig.)

  3. Helical CT angiography of renal arteries: two-years of experience

    International Nuclear Information System (INIS)

    Beregi, J.P.; Louvegny, S.; Ceugnart, L.; Willoteaux, S.; Elkohen, M.; Desmoucelle, F.; Deklunder, G.; Wattinne, L.

    1997-01-01

    To evaluate the role of helical CT angiography (CTA) in the detection of renal artery stenosis in hypertensive patients. We studied 300 hypertensive patients (50 prospectively and 250 consecutively) with CTA and arteriography (n = 118). Helical acquisition (collimation 3 mm; pitch = 1, 20 seconds acquisition time) was performed 20-45 seconds after contrast injection (300 mgl/ml; 120 ml, 4 ml/sec. Transverse axial views and 3D reconstructions were analysed (360 deg interpolation algorithm, 1 mm overlapped). In the prospective series, CTA sensibility was 100 % for main renal artery stenoses and specificity was 98.2 %; however 7/32 renal accessory arteries were not visualized. In the 300 patients studies, seventy-four stenoses were detected. There were 5 false-positive and 5 false-negative studies. Secondary hypertension was detected in 26 % of patients (including 14 cases of adrenal hyperplasia). CTA is a promising technique for the detection of renal artery stenosis in hypertensive patients. (authors)

  4. Helical CT finding of carotid-cavernous fistula: a sign of early enhancing superior ophthalmic vein

    International Nuclear Information System (INIS)

    Kim, Jae Hyung; Na, Dong Gyu; Byun, Hong Sik; Ryoo, Jae Wook

    2000-01-01

    The purpose of this study was to determine the diagnostic value of a sign of early enhancing superior ophthalmic vein (SOV), as seen on helical CT images in patients with carotid-cavernous fistula (CCF). This study involved 16 patients with CCF and 28 control patients. Axial CT images with scanning delays of 30 seconds following bolus injection of contrast material (90 mL, 3 mL/sec) were obtained, and this procedure was followed by coronal CT imaging. To determine the presence or absence of early enhancement or, dilatation of the SOV, bulging of the cavernous sinus, and enlargement of extraocular muscle, CT images were analysed by three observers in a blinded, random manner. Early enhancement of SOV was determined to be present where enhancement of the SOV was similar to or stronger than that of the ipsilateral posterior cerebral artery. A sign of early enhancing SOV was seen in 14 of the 16 patients with CCF but in no control patients (88% sensitivity and 100% specificity). The respective sensitivity and specificity of other CT features were 71% and 100% (dilatation of the SOV, as seen on axial images), 60% and 83% (dilatation of the SOV, as seen on coronal images), 71% and 89% (dilatation of the cavernous sinus), and 65% and 98% (enlargement of extraocular muscle). A sign of early enhancing SOV is a characteristic and specific CT finding of CCF, and is useful for the diagnosis of CCF. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

    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)

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

    International Nuclear Information System (INIS)

    Tozaki, Mitsuhiro; Hayashi, Katsuhiko; Fukuda, Kunihiko

    2001-01-01

    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)

  7. Three-dimensional helical (spiral) CT angiography. Visualization of vessels in the maxillofacial regions

    International Nuclear Information System (INIS)

    Hanawa, Shigeo; Sakamoto, Hidetomo; Mori, Shin-ichiro; Kagawa, Toyohiro; Seze, Ryosuke; Ishioka, Hisakazu; Tashiro, Himiko; Ogawa, Kazuhisa; Wada, Tadako

    1998-01-01

    Authors performed the contrast helical CT for tumors on the maxillofacial regions, and reconstituted these data into the three-dimensional helical (spiral) CT angiography (CTA). Furthermore the conditions of photographing and the clinical significance of CTA were discussed. The subjects were 24 cases (including 13 of malignant tumors, 4 of benign tumors, 4 of inflammation and 3 of malformations), to which the contrast helical CT was performed transvenously. The photographing condition was set in principal to 140 kV of the tube voltage, 160 (200) mA of the tube current, 3 mm of the X-ray beam width, 3 mm/sec (pitch=1) of the turn-table moving speed. The relationship between the beam width and the pitch was determined by the phantom experiments. The scanning was carried out maximally for continuous 60 sec as the scanning time of a turn/sec. Of all cases, CTA visualized three-dimensionally vessels, but it was hard in the total carotid arteries and the internal-external carotid arteries. Authors analyzed the axial and the multiplanar reconstitution (MPR) images as the two-dimensional display, and the surface rendering (SR), the volume rendering and the maximum intensity projections (MIP) as the three-dimensional display. The axial and MPR image of the facial arteries and the lingual arteries as the branched vessels from the external carotid arteries were recognized easily. By SR, it was easily to understand the anatomical relationship among vessels, gnathic bone and cervical vertebrae, and by MIP sufficiently observe the concentration dependent calcification of the vessel walls. Three-dimensional CTA is very useful to get the three-dimensional visual information about the anatomical structures of the maxillofacial regions which is necessary for oral surgeons to plan the pre-operational strategies. (K.H.)

  8. The role of 3D Helical CT in the reconstructive treatment of maxillofacial cancers

    International Nuclear Information System (INIS)

    De Rosa, V.; Ziviello, M.; Ionna, F.; Mozzillo, N.; Parascandolo, S.

    2000-01-01

    Purpose of this work is to investigate the role of Helical CT and the usefulness of three-dimensional (3D) imaging for pre-operative planning and follow-up of reconstructive maxillofacial surgery with alloplastic material in neoplastic disease involving this region. From 1996 to 1999 eleven patients were examined with Helical CT and 3D images for planning of maxillofacial plastic and reconstructive surgery for advanced cancer of this anatomically complex region. A 3D-modulated titanium mesh (100%) or micro nets was used to rebuild the anterior surface of maxillary bone and the orbital floor. The mesh was cut to the appropriate size and shape and curved where necessary. Within the residual sinusal cavity a siliconed filling was used surmounting an acrylic prosthesis with dental arch to rebuild the palate. A rehydrated bovine pericardium was affixed and moduled on the borders in two cases only. Three-dimensionally reconstructed CT images were obtained preoperatively and at least 6 months postoperatively in all patients. The images were generated on a computer workstation using the shaded surface display (SSD) software with threshold values ranging 425 to 630 HU, and a more closed window for the imaging of titanium mesh/bone interface in the post surgical follow-up. It was obtained an excellent complete spatial depiction of maxillo facial region both before and after surgery, with no artefacts so important as to affect the 3D reconstruction process and the image quality. Together with the head-neck surgical team it could be worked for preoperative planning through CT scans by different 3D points of view. The 3D reconstructed follow-up scans showed good filling of the defect in the area where the titanium mesh had been used. Then efficacious bone modelling and good biocompatibility of the alloplastic material were seen in all patients, with no inflammatory reactions. Titanium is a well-known material, which is widely used for cranioplasty. It is a radiolucent, non

  9. Usefulness of the helical CT in gastro intestinally caused acute abdomen

    International Nuclear Information System (INIS)

    Cruz, R. A. de la; Martel, J.; Albillos, J. C.; Oliver, J. M.; Lopez, J.; Trapero, M. A.

    2000-01-01

    At present, there is a vivid debate on the role of the Helical CT (HCT) in the acute abdomen, principally on the usefulness of the non contrast HCT. We aim to present the most common semiological findings and the differential diagnoses, and to give a short description of the indications and protocols, according to the existing literature and to our experience with HCT during the last three years. We believe that the generalization of the use of HCT in emergencies avoid unnecessary surgery and shorten observation times on many occasions, with clear benefits in the clinical management of the patients. (Author) 30 refs

  10. Motion tolerant iterative reconstruction algorithm for cone-beam helical CT imaging

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, Hisashi; Goto, Taiga; Hirokawa, Koichi; Miyazaki, Osamu [Hitachi Medical Corporation, Chiba-ken (Japan). CT System Div.

    2011-07-01

    We have developed a new advanced iterative reconstruction algorithm for cone-beam helical CT. The features of this algorithm are: (a) it uses separable paraboloidal surrogate (SPS) technique as a foundation for reconstruction to reduce noise and cone-beam artifact, (b) it uses a view weight in the back-projection process to reduce motion artifact. To confirm the improvement of our proposed algorithm over other existing algorithm, such as Feldkamp-Davis-Kress (FDK) or SPS algorithm, we compared the motion artifact reduction, image noise reduction (standard deviation of CT number), and cone-beam artifact reduction on simulated and clinical data set. Our results demonstrate that the proposed algorithm dramatically reduces motion artifacts compared with the SPS algorithm, and decreases image noise compared with the FDK algorithm. In addition, the proposed algorithm potentially improves time resolution of iterative reconstruction. (orig.)

  11. "Porcelain heart" cardiomyopathy secondary to hyperparathyroidism: radiographic, echocardiographic, and cardiac CT appearances.

    LENUS (Irish Health Repository)

    Freeman, James

    2012-02-01

    We report the radiographic, echocardiographic and cardiac CT appearances of \\'porcelain heart\\' in an 85-year-old woman who presented with progressive heart failure. The extensive myocardial calcification was secondary to hyperparathyroidism with renal failure.

  12. "Porcelain heart" cardiomyopathy secondary to hyperparathyroidism: radiographic, echocardiographic, and cardiac CT appearances.

    LENUS (Irish Health Repository)

    Freeman, James

    2010-11-01

    We report the radiographic, echocardiographic and cardiac CT appearances of \\'porcelain heart\\' in an 85-year-old woman who presented with progressive heart failure. The extensive myocardial calcification was secondary to hyperparathyroidism with renal failure.

  13. The detectability of hepatic metastases in candidates of radiofrequency ablation: comparison for helical CT scanning and late-phase pulse-inversion harmonic imaging

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kang Won; Yoon, Kwon Ha; Kim, Eun A; Park, Ki Han; Juhng, Seon Kwan; Won, Jong Jin [School of Medicine, Wonkwang Univ., Iksan (Korea, Republic of)

    2002-02-01

    To compare dual-phase helical CT and pulse inversion harmonic US using microbubble contrast agents in the detection of hepatic metastases prior to radiofrequency (RF) ablation. Twenty-one patients in whom hepatic metastases from colorectal cancer had been diagnosed by dual-phase CT scanning and who were considered to be candidates for RF ablation underwent pulse-inversion barmonic US examination. Images were obtained 5 minutes after the bolus injection of microbubble contrast agent SH U 508 A (4.0 g, 300 mg/mL). The number of metastatic tumors revealed by CT and US was determined, and the findings were statistically analysed. The influence of the results of US examination on treatment planning was also evaluated. In 21 patients, 48 metastaic lesions were detected by helical CT, and 56 lesions by US. These eight additional lesions revealed by US occurred in six patients (29%), and their diameter was 3-13 (mean, 7.2) mm. In three of these patients, RF ablation could not be performed ,while in the other three, the additional lesions were ablated. Pulse-inversion harmonic US imaging using microbubble contrast agents may depict small hepatic metastatic tumors that were not apparent at CT. US-therefore appears to be useful in the planning of treatment prior to the RF ablation of hepatic metastases.

  14. Preoperative evaluation of renal anatomy and renal masses with helical CT, 3D-CT and 3D-CT angiography.

    Science.gov (United States)

    Toprak, Uğur; Erdoğan, Aysun; Gülbay, Mutlu; Karademir, Mehmet Alp; Paşaoğlu, Eşref; Akar, Okkeş Emrah

    2005-03-01

    The aim of this prospective study was to determine the efficacy of three-dimensional computed tomography (3D-CT) and three-dimensional computed tomographic angiography (3D-CTA) that were reconstructed by using the axial images of the multiphasic helical CT in the preoperative evaluation of renal masses and demonstration of renal anatomy. Twenty patients that were suspected of having renal masses upon initial physical examination and ultrasonographic evaluation were examined through multiphasic helical CT. Two authors executed CT evaluations. Axial images were first examined and then used to reconstruct 3D-CT and 3D- CTA images. Number, location and size of the renal masses and other findings were noted. Renal vascularization and relationships of the renal masses with the neighboring renal structures were further investigated with 3D-CT and 3D-CTA images. Out of 20 patients, 13 had histopathologically proven renal cell carcinoma. The diagnoses of the remaining seven patients were xanthogranulomatous pyelonephritis, abscess, simple cyst, infected cyst, angiomyolipoma, oncocytoma and arteriovenous fistula. In the renal cell carcinoma group, 3 patients had stage I, 7 patients had stage II, and 3 patients had stage III disease. Sizes of renal cell carcinoma masses were between 23 mm to 60 mm (mean, 36 mm). Vascular invasion was shown in 2 renal cell carcinoma patients. Collecting system invasion was identified in 11 of 13 renal cell patients. These radiologic findings were confirmed with surgical specimens. Three-dimensional CT and 3D-CTA are non-invasive, effective imaging techniques for the preoperative evaluation of renal masses.

  15. Hepatic parenchymal perfusion abnormalities after pancreaticobiliary surgery. Evaluation with dynamic helical CT

    International Nuclear Information System (INIS)

    Mitsuzaki, K.; Yamashita, Y.; Ogata, I.; Nishiharu, T.; Urata, J.; Takahashi, M.

    1998-01-01

    Purpose: To evaluate perfusion abnormalities of the liver after pancreaticobiliary surgery. Material and Methods: We retrospectively evaluated 128 patients with pancreaticobiliary malignant tumors who had been examined both before and after surgery by means of helical CT of the liver. An infusion of 3 ml/s of 60% nonionic contrast material was followed by helical CT of the liver in a sequential arterial phase, portal venous phase, and equilibrium phase. Results: Of 128 patients, we followed 97. In 21 patients (22%) we found 47 lesions with perfusion abnormalities that were detected 1-33 months (mean 6.6 months) after the operation. All patients were asymptomatic. The shape of each perfusion abnormality was characterized as geographic (n=23, 47%), wedge-shaped (n=21, 45%), or round (n=3, 8%). The abnormalities were seen in the arterial phase in 46 lesions (98%), in the portal venous phase in 18 lesions (38%), and in the equilibrium phase in 1 lesion (0.2%). In all lesions, the size either decreased spontaneously, or it remained unchanged for more than one year. Conclusion: Perfusion abnormalities of the liver may occur in patients who undergo pancreaticobiliary surgery. These findings should not be confused with hypervascular metastases. (orig.)

  16. Hepatic parenchymal perfusion abnormalities after pancreaticobiliary surgery. Evaluation with dynamic helical CT

    Energy Technology Data Exchange (ETDEWEB)

    Mitsuzaki, K.; Yamashita, Y.; Ogata, I.; Nishiharu, T.; Urata, J.; Takahashi, M. [Kumamoto Univ., School of Medicine, Dept. of Radiology (Japan)

    1998-05-01

    Purpose: To evaluate perfusion abnormalities of the liver after pancreaticobiliary surgery. Material and Methods: We retrospectively evaluated 128 patients with pancreaticobiliary malignant tumors who had been examined both before and after surgery by means of helical CT of the liver. An infusion of 3 ml/s of 60% nonionic contrast material was followed by helical CT of the liver in a sequential arterial phase, portal venous phase, and equilibrium phase. Results: Of 128 patients, we followed 97. In 21 patients (22%) we found 47 lesions with perfusion abnormalities that were detected 1-33 months (mean 6.6 months) after the operation. All patients were asymptomatic. The shape of each perfusion abnormality was characterized as geographic (n=23, 47%), wedge-shaped (n=21, 45%), or round (n=3, 8%). The abnormalities were seen in the arterial phase in 46 lesions (98%), in the portal venous phase in 18 lesions (38%), and in the equilibrium phase in 1 lesion (0.2%). In all lesions, the size either decreased spontaneously, or it remained unchanged for more than one year. Conclusion: Perfusion abnormalities of the liver may occur in patients who undergo pancreaticobiliary surgery. These findings should not be confused with hypervascular metastases. (orig.).

  17. Assessment of intraocular foreign bodies by helical-CT multiplanar imaging

    International Nuclear Information System (INIS)

    Papadopoulos, A.; Fotinos, A.; Maniatis, V.; Kavadias, S.; Michaelides, A.; Avouri, M.; Kalamara, C.; Stringaris, K.

    2001-01-01

    The aim of this study was to examine the effectiveness of helical CT in the assessment of intraocular foreign bodies, evaluating two protocols with different collimation. We performed helical-CT studies in 30 patients. Fifteen patients were examined with 1.5-mm collimation and the other 15 patients with 3.0-mm collimation. All other imaging parameters were identical in both protocols. Multiplanar images were reconstructed. The examinations were reviewed for presence, localization and size of intraocular foreign bodies. We compare our results with the surgical data. We estimate the required examination time. In the first group (collimation 1.5 mm) an intraorbital foreign body was detected in 8 of 15 patients. In 3 of 8 patients an intraocular foreign body (all were metallic) was detected. In the second group (collimation 3.0 mm) an intraorbital foreign body was detected in 9 of 15 patients. In 8 of 9 patients an intraocular foreign body (all were metallic) was detected. Our results were confirmed by surgery in all cases. Examination time was 36 s in the first group and 18 s in the second group. Computed tomography should be considered the imaging modality of choice in the assessment of metallic intraocular foreign bodies and 3.0-mm collimation is optional, because of reduced examination time and radiation exposure. (orig.)

  18. The significance of multi-slice helical CT multiplanar reconstruction in the diagnoses of laryngeal carcinoma

    International Nuclear Information System (INIS)

    Li Lin; Luo Dehong; Zhou Chunwu; Zhao Xinming; Jiang Liming; Huang Yao; Jiang Lingxia; Li Jing; Wu Ning

    2006-01-01

    Objective: To evaluate the significance of multi-slice helical CT with multiplanar reconstruction in laryngeal carcinoma. Methods: Thirty-five patients with laryngeal carcinoma were studied by helical CT, MPR were subsequently done. The lesion extent of the axial image findings, MPR findings and the combined image findings were compared with the pathological results respectively. The data were statistically analyzed. Results: In the evaluation of the anterior commissure, the axial image findings, MPR findings and the combined image findings were 82.9%, 68.6% and 91.4% in accuracy respectively, the results were statistically different (P 0.05). The combined images were superior to the axial images and the MPR images in sensitivity, specificity and accuracy of the lesion extent. Conclusion: The axial images could show the shape, size, extension of the tumor and the lymphadenopathy, MPR images displayed the shape, size and extension roundly and directly, they were the supplement for the axial images. Axial images combined with MPR could improve the accuracy in the diagnoses of laryngeal carcinoma. (authors)

  19. Anterior glenoid rim fracture: the value of helical CT with threedimensional reconstruction and electronic humeral disarticulation

    Directory of Open Access Journals (Sweden)

    Heverton César de Oliveira

    2003-06-01

    Full Text Available Objectives: To show a new three-dimensional reconstructiontechnique based on helical computed tomography images withelectronic humeral disarticulation in anterior glenoid rim fractures,correlating the anatomic specimen with simulation of an anteriorglenoid rim fracture, as well as evaluating the extension of thefracture, the bone fragment position and distance in relation to theglenoid cavity in six patients. Methods: One scapula and onehumerus with no signs of fracture or congenital malformationswere placed in anatomical position using an adhesive tape aftersimulating an anterior glenoid rim fracture made by an osteotome.Helical CT imaging was acquired and three-dimensionalreconstructions were made based on these images, with andwithout electronic humeral disarticulation. The bone fragment waslocated, measured and its position in relation to the glenoid cavitywas assessed. Six patients with anterior glenoid rim fracture weresubmitted to CT of the shoulder using the same parameters asthose applied to the anatomic specimen. Results: In the anatomicspecimen and in all six patients the bone fragment was clearlydemonstrated; bone fragment measurements in the anatomicspecimen and in three-dimensional reconstructions wereequivalent. The fragment was better demonstrated in the imagestaken with electronic humeral disarticulation, particularly in thefrontal view of the glenoid cavity as observed in all six patients.Conclusion: We concluded that our experiment with the anatomicspecimen and the study of six patients allow us to state that thistechnique is safe and accurate to demonstrate the extension, sizeand location of the bone fragment in anterior glenoid rim fractures,and it provides essential elements for therapeutic planning.

  20. CT appearance of complications related to thoracic endovascular aortic repair (TEVAR): a pictorial essay

    International Nuclear Information System (INIS)

    Pua, U.; Tay, K.H.; Tan, B.S.; Htoo, M.M.; Sebastian, M.; Sin, K.; Chua, Y.L.

    2009-01-01

    Thoracic endovascular aortic repair (TEVAR) is a recognized treatment for various diseases involving the thoracic aorta. Patients treated with TEVAR require lifelong surveillance for potential complications, with CT being highly utilized in most centres. Endoleak is the most common complication and can be detected using CT. However, other complications such as stent strut perforations and end organ ischemia can also be detected on CT. The purpose of this pictorial essay is to illustrate the CT appearance of post-TEVAR complications encountered in our institution and to highlight their significance. (orig.)

  1. CT appearance of complications related to thoracic endovascular aortic repair (TEVAR): a pictorial essay

    Energy Technology Data Exchange (ETDEWEB)

    Pua, U. [Singapore General Hospital, Department of Diagnostic Radiology, Singapore (Singapore); Tan Tock Seng Hospital, Department of Diagnostic Radiology, Singapore (Singapore); Tay, K.H.; Tan, B.S.; Htoo, M.M. [Singapore General Hospital, Department of Diagnostic Radiology, Singapore (Singapore); Sebastian, M. [Singapore General Hospital, Department of General Surgery, Singapore (Singapore); Sin, K.; Chua, Y.L. [National Heart Centre, Department of Cardiothoracic and Vascular Surgery, Singapore (Singapore)

    2009-05-15

    Thoracic endovascular aortic repair (TEVAR) is a recognized treatment for various diseases involving the thoracic aorta. Patients treated with TEVAR require lifelong surveillance for potential complications, with CT being highly utilized in most centres. Endoleak is the most common complication and can be detected using CT. However, other complications such as stent strut perforations and end organ ischemia can also be detected on CT. The purpose of this pictorial essay is to illustrate the CT appearance of post-TEVAR complications encountered in our institution and to highlight their significance. (orig.)

  2. Image quality of high-resolution CT with 16-channel multidetector-row CT. Comparison between helical scan and conventional step-shoot scan

    International Nuclear Information System (INIS)

    Sumikawa, Hiromitsu; Johkoh, Takeshi; Koyama, Mitsuhiro

    2005-01-01

    The aim of this study was to evaluate the image quality of high-resolution CT (HRCT) reconstructed from volumetric data with 16-channel multidetector-row CT (MDCT). Eleven autopsy lungs that were diagnosed histopathologically were scanned by 16-channel MDCT with the step-and-shoot scan mode and three helical scan modes. Each helical mode had each size of focal spot, pitch, and time of gantry rotation. HRCT images were reconstructed from the volumetric data with each helical mode and axial sequence data. Two observers evaluated the image quality and noted the most appropriate diagnosis for each imaging. Visualization of abnormal structures with one helical mode was equal to those with axial mode, whereas those with the other two helical modes were inferior to those with axial mode (Wilcoxon signed rank test; p<0.0001). There was no significant difference in diagnostic efficacy between modes. The image quality of HRCT with appropriate helical mode is equal to that with axial mode and diagnostic efficacy is equal among all modes. These results may indicate that sufficient HRCT images can be obtained by only one helical scan without the addition of conventional axial scans. (author)

  3. The efficacy of low-dose helical CT screening as an option for health examination

    International Nuclear Information System (INIS)

    Kishi, Kazuma; Hara, Shigeko; Kurosaki, Atsuko; Fujii, Takeshi; Yoshimura, Kunihiko

    2007-01-01

    We retrospectively evaluated the results of low-dose helical CT screening as an option for health examinations. From November 2002 to October 2005, CT screening was performed in 2,306 individuals (men 1,766, women 540, mean age 56.1 years). Among them, 71 individuals (3.1%) were diagnosed as having active thoracic diseases consisting of 14 neoplasms and 57 non-neoplastic diseases. Of 14 patients with neoplastic lesions, 13 had lung cancer, 1 of whom had double primary lung cancer, and 1 had atypical adenomatous hyperplasia. The mean diameter of the 14 lung cancers was 14.4 mm. The histology of these lesions was adenocarcinoma in 13 and squamous cell carcinoma in 1. The pathological stage was IA in 12 patients and IIA in 1. All patients underwent surgical resection. On the other hand, emphysema was diagnosed in 40 asymptomatic individuals based on CT and spirometry, and smoking cessation was strongly implemented for those who were current smokers. CT screening is useful for detecting not only early lung cancer but also non-neoplastic lung diseases. (author)

  4. Maximum-intensity-projection CT angiography for evaluating head and neck tumors. Usefulness of helical CT and auto bone masking method

    International Nuclear Information System (INIS)

    Sakai, Osamu; Nakashima, Noriko; Ogawa, Chiaki; Shen, Yun; Takata, Yasunori; Azemoto, Shougo.

    1994-01-01

    Angiographic images of 10 adult patients with head and neck tumors were obtained by helical computed tomography (CT) using maximum intensity projection (MIP). In all cases, the vasculature of the head and neck region was directly demonstrated. In the head and neck, bone masking is a more important problem than in other regions. We developed an effective automatic bone masking method (ABM) using 2D/3D connectivity. Helical CT angiography with MIP and ABM provided accurate anatomic depiction, and was considered to be helpful in preoperative evaluation of head and neck tumors. (author)

  5. 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.

  6. FDG PET/CT appearance of local osteosarcoma recurrences in pediatric patients

    Energy Technology Data Exchange (ETDEWEB)

    Sharp, Susan E.; Gelfand, Michael J. [Cincinnati Children' s Hospital Medical Center, Department of Radiology, Cincinnati, OH (United States); Shulkin, Barry L.; McCarville, M.B. [St. Jude Children' s Research Hospital, Department of Diagnostic Imaging, Memphis, TN (United States)

    2017-12-15

    Osteosarcoma is the most common pediatric malignant bone tumor, frequently surgically managed with limb salvage rather than amputation. Local recurrences are seen in up to 9% of osteosarcoma patients, with CT and MRI imaging often limited by metal artifacts. To describe the [F-18]2-fluoro-2-deoxyglucose (FDG) PET/CT appearance of local osteosarcoma recurrences with correlation to findings on other imaging modalities. A retrospective review of pediatric osteosarcoma patients imaged with FDG PET/CT was performed in patients with pathologically proven local recurrences. FDG PET/CT findings were reviewed and correlated with available comparison imaging studies. Ten local osteosarcoma recurrences in eight pediatric osteosarcoma patients were imaged with FDG PET/CT. All eight patients had a local recurrence after limb salvage; two patients had a second local recurrence after amputation. All local recurrences were seen with FDG PET/CT, demonstrating solid (n=5) or peripheral/nodular (n=5) FDG uptake patterns. Maximum standard uptake values (SUVs) ranged from 3.0 to 15.7. In five recurrences imaged with FDG PET/CT and MRI, MRI was limited or nondiagnostic in three. In four recurrences imaged with FDG PET/CT and bone scan, the bone scan was negative in three. Local osteosarcoma recurrences are well visualized by FDG PET/CT, demonstrating either solid or peripheral/nodular FDG uptake with a wide range of maximum SUVs. FDG PET/CT demonstrates the full extent of local recurrences, while MRI can be limited by artifact from metallic hardware. PET/CT appears to be more sensitive than bone scan in detecting local osteosarcoma recurrences. (orig.)

  7. Helical CT findings of gastric wall thickening by peptic ulcer : compared with gastric adenocarcinoma with ulcer

    International Nuclear Information System (INIS)

    Jung, Won Jung; Choi, Jong Chul; Seo, Keum Soo; Koo, Bon Sik; Park, Byeong Ho; Kim, Chung Ku; Lee, Ki Nam; Nam, Kyung Jin

    2000-01-01

    To compare on the basis of helical CT findings gastric wall thickening of peptic gastric ulcer with that of gastric adenocarcinoma with ulcer. Thirty-eight patients with pathologically proven gastric lesion (17 cases of peptic ulcer and 21 cases of ulcerative or ulceroinfiltrative gastric cancer (Borrman type II, III) underwent helical CT, and the findings were retrospectively reviewed in terms of maximum abnormal wall thickness, preservation of the inner enhancing layer, the presence three discriminate layers of gastric wall, and enhancement pattern. The enhancement pattern of abnormally thick wall was compared with that of the portal phase of back muscle, and was defined as low, iso, or high. The Chi-square test and Student t test were used for statistical analysis. In cases of peptic ulcer and gastric cancer with ulceration, maximum abnormal wall thickness was 7-30 (mean, 16.1)mm, and 11-33 (mean, 21.8)mm, respectively. The inner enhancing layer was preserved in 15 of 17 patients (88.2%) and one of 21 (4.8%); three discriminate layers of gastric wall were observed in 8 of 17 patients (47.0%), and one of 21 (4.8%). The enhancement pattern was low in 12 of 17 patients (70.5%), and 3 of 21 (14.3%); iso in 4 of 17 (23.5%), and 4 of 21 (19.0%), and high in one of 17 (5.9%), and 14 of 21 (66.7%). All figures refer, respectively, to the two distinct conditions. In terms of preservation of the inner enhancing layer, three discriminate layers of gastric wall, and a low enhancement pattern, there were statistically significant differences between peptic ulcer and gastric adenocarcinoma with ulcer. Where the enhancement was high, however, the statistically significant difference between the two conditions was even greater. There was no statistically significant difference in terms of gastric wall thickness or iso-attenuation of thickened gastric. Helical CT findings of gastric wall thickening, preservation of the inner enhancing layer, and three discriminate layers of

  8. Helical CT findings of gastric wall thickening by peptic ulcer : compared with gastric adenocarcinoma with ulcer

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Won Jung; Choi, Jong Chul; Seo, Keum Soo; Koo, Bon Sik; Park, Byeong Ho; Kim, Chung Ku; Lee, Ki Nam; Nam, Kyung Jin [College of Medicine, Dong A University, Pusan (Korea, Republic of)

    2000-02-01

    To compare on the basis of helical CT findings gastric wall thickening of peptic gastric ulcer with that of gastric adenocarcinoma with ulcer. Thirty-eight patients with pathologically proven gastric lesion (17 cases of peptic ulcer and 21 cases of ulcerative or ulceroinfiltrative gastric cancer (Borrman type II, III)) underwent helical CT, and the findings were retrospectively reviewed in terms of maximum abnormal wall thickness, preservation of the inner enhancing layer, the presence three discriminate layers of gastric wall, and enhancement pattern. The enhancement pattern of abnormally thick wall was compared with that of the portal phase of back muscle, and was defined as low, iso, or high. The Chi-square test and Student t test were used for statistical analysis. In cases of peptic ulcer and gastric cancer with ulceration, maximum abnormal wall thickness was 7-30 (mean, 16.1)mm, and 11-33 (mean, 21.8)mm, respectively. The inner enhancing layer was preserved in 15 of 17 patients (88.2%) and one of 21 (4.8%); three discriminate layers of gastric wall were observed in 8 of 17 patients (47.0%), and one of 21 (4.8%). The enhancement pattern was low in 12 of 17 patients (70.5%), and 3 of 21 (14.3%); iso in 4 of 17 (23.5%), and 4 of 21 (19.0%), and high in one of 17 (5.9%), and 14 of 21 (66.7%). All figures refer, respectively, to the two distinct conditions. In terms of preservation of the inner enhancing layer, three discriminate layers of gastric wall, and a low enhancement pattern, there were statistically significant differences between peptic ulcer and gastric adenocarcinoma with ulcer. Where the enhancement was high, however, the statistically significant difference between the two conditions was even greater. There was no statistically significant difference in terms of gastric wall thickness or iso-attenuation of thickened gastric. Helical CT findings of gastric wall thickening, preservation of the inner enhancing layer, and three discriminate layers of

  9. Angiomyolipoma with minimal fat: Differentiation from papillary renal cell carcinoma by helical CT

    International Nuclear Information System (INIS)

    Zhang, Y.-Y.; Luo, S.; Liu, Y.; Xu, R.-T.

    2013-01-01

    Aim: To evaluate whether helical computed tomography (CT) images can be used to differentiate angiomyolipomas (AMLs) with minimal fat from papillary renal cell carcinomas (PRCCs) based on their morphological characteristics and enhancement features. Materials and methods: This retrospective study was approved by the institutional review board. Informed consent was waived. Forty-four patients (21 with AMLs with minimal fat and 23 with PRCCs) who underwent enhanced helical CT before total or partial nephrectomy were included. Two radiologists, who were blinded to the histopathology results, read the CT images and recorded the attenuation value, morphological characteristics, and enhancement features of the tumours, which were subsequently evaluated. An independent samples t-test, χ 2 test, and rank sum test were performed between the tumours. The predictive value of a CT finding was determined by multivariate logistic regression analysis. Results: AML with minimal fat had an apparent female prevalence (p < 0.01). Intra-tumoural vessels were noted in 11 cases of AML with minimal fat and three PRCC cases (p < 0.01). The unenhanced attenuation characteristic was significantly different between the two diseases (p < 0.001). The absolute attenuation values (AAVs) and the corrected attenuation values (CAVs) of the AML with minimal fat group of unenhanced and two phases of enhanced images were greater compared with that of the PRCC group (p < 0.05). After contrast medium injection, the tumour enhancement value (TEV) of the AML with minimal fat group in the corticomedullary phase was greater than that of the PRCC group (p < 0.01). Most cases of both tumour types demonstrated early enhancement characteristics; the enhancement value of the AML with minimal fat group was greater compared with that of the PRCC group (p < 0.01). The unenhanced attenuation characteristic, intra-tumoural vessels, and CAVs of unenhanced and early excretory phase scans were valuable parameters to

  10. COMPUTED TOMOGRAPHY DOSE INDEX MEASUREMENT FOR Hi-ART MEGAVOLTAGE HELICAL CT.

    Science.gov (United States)

    Liu, Minglu; Wang, Yunlai; Liao, Xiongfei

    2016-11-01

    On-line megavoltage computed tomography (MVCT) images are used to verify patient daily set-up in Hi-ART helical TomoTherapy unit. To evaluate the patient dose from MVCT scanning in image guidance, weighted computed tomography (CT) dose index (CTDI w ) was measured with PTW TM30009 CT pencil chamber in head and body phantoms for slice thicknesses of 2, 4 and 6 mm with different scan lengths. Dose length products (DLPs) were subsequently calculated. The CTDI w and DLP were compared with XVI kV CBCT and Brilliance simulator CT for routine clinical protocols. It was shown that CTDI and DLP had close relationship with the slice thickness and the scan length. The dose distribution in the transversal plane was very inhomogeneous due to the attenuation of the couch. Patient dose from MVCT was lower than XVI CBCT for the head scan, while larger for body scan. CTDI w , which is measured easily and reproducibly, can be used to assess the patient dose in MVCT. Regular measurement should be performed in QA & QC programmes. Appropriate slice thickness and scan range should be chosen to reduce the patient dose. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  11. CT and angiographic appearances of hepatocellular carcinoma partially fed by right inferior phrenic artery

    Energy Technology Data Exchange (ETDEWEB)

    Ohtomo, Kuni; Furui, Shigeru; Yoshikawa, Hiroki; Yashiro, Naofumi; Araki, Tsutomu [Tokyo Univ. (Japan). Faculty of Medicine

    1983-04-01

    CT and angiographic appearances of 8 hepatocellular carcinomas which were partially fed by right inferior phrenic artery were discussed. CT demonstrated tumor fully occupied posterior segment of right hepatic lobe in 6 cases which were composed of 3 solitary massive, 2 massive nodular and 1 confluent massive angiographically. In the other 2 cases, CT showed encapsulated tumor in posterior inferior portion of posterior segment protruded from the liver. In 6 out of these 8 cases, tumor vessels and tumor stain were chiefly derived from posterior branch of right inferior phrenic artery.

  12. CT and angiographic appearances of hepatocellular carcinoma partially feeded by right inferior phrenic artery

    International Nuclear Information System (INIS)

    Ohtomo, Kuni; Furui, Shigeru; Yoshikawa, Hiroki; Yashiro, Naofumi; Araki, Tsutomu

    1983-01-01

    CT and angiographic appearances of 8 hepatocellular carcinomas which were partially feeded by right inferior phrenic artery were discussed. CT demonstrated tumor fully occupied posterior segment of right hepatic lobe in 6 cases which were composed of 3 solitary massive, 2 massive nodular and 1 confluent massive angiographically. In the other 2 cases, CT showed encapsulated tumor in posterior inferior portion of posterior segment protruded from the liver. In 6 out of these 8 cases, tumor vessels and tumor stain were chiefly derived from posterior branch of right inferior phrenic artery. (author)

  13. CT appearances of unilateral cleft palate 20 years after bone graft surgery

    International Nuclear Information System (INIS)

    Kolbenstvedt, A.; Aaloekken, T.M.

    2002-01-01

    Purpose: To describe CT appearances in patients with unilateral cleft lip and palate (CLP) 20 years after bone graft surgery. Material and Methods: Eighteen consecutive patients with unilateral CLP were examined. All patients had been treated with primary closure, both in infancy and early childhood, supplemented with bone grafting at the age of around 10 years. The CT examination of the upper jaw included a dental CT program. The CT appearances of the cleft side were compared with those of the untreated non-cleft side. Results: Abnormal CT appearances included skew nasal aperture (n=17), nasal septal deviation (n=17), low floor of nasal aperture (n=15) at or towards the cleft side, and deviation of anterior nasal spine towards the non-cleft side (n=18). The posterior part of the bone cleft was visible in all patients, and the dental arch was V-shaped in 8. Conclusion: Although adherence to the present treatment protocol is considered to give satisfactory functional and cosmetic results, certain abnormalities persist. A knowledge of these is a prerequisite for a complete and final evaluation of the surgical and orthodontic regimen. Cleft palate nasal cavity abnormalities CT

  14. CT appearances of unilateral cleft palate 20 years after bone graft surgery

    Energy Technology Data Exchange (ETDEWEB)

    Kolbenstvedt, A.; Aaloekken, T.M. [Rikshospitalet, Oslo (Norway). Dept. of Radiology; Arctander, K. [Rikshospitalet, Oslo (Norway). Dept. of Plastic Surgery; Johannessen, S. [Inst. of Clinical Dentistry, Oslo (Norway)

    2002-11-01

    Purpose: To describe CT appearances in patients with unilateral cleft lip and palate (CLP) 20 years after bone graft surgery. Material and Methods: Eighteen consecutive patients with unilateral CLP were examined. All patients had been treated with primary closure, both in infancy and early childhood, supplemented with bone grafting at the age of around 10 years. The CT examination of the upper jaw included a dental CT program. The CT appearances of the cleft side were compared with those of the untreated non-cleft side. Results: Abnormal CT appearances included skew nasal aperture (n=17), nasal septal deviation (n=17), low floor of nasal aperture (n=15) at or towards the cleft side, and deviation of anterior nasal spine towards the non-cleft side (n=18). The posterior part of the bone cleft was visible in all patients, and the dental arch was V-shaped in 8. Conclusion: Although adherence to the present treatment protocol is considered to give satisfactory functional and cosmetic results, certain abnormalities persist. A knowledge of these is a prerequisite for a complete and final evaluation of the surgical and orthodontic regimen. Cleft palate nasal cavity abnormalities CT.

  15. Implementation techniques and acceleration of DBPF reconstruction algorithm based on GPGPU for helical cone beam CT

    International Nuclear Information System (INIS)

    Shen Le; Xing Yuxiang

    2010-01-01

    The derivative back-projection filtered algorithm for a helical cone-beam CT is a newly developed exact reconstruction method. Due to its large computational complexity, the reconstruction is rather slow for practical use. General purpose graphic processing unit (GPGPU) is an SIMD paralleled hardware architecture with powerful float-point operation capacity. In this paper,we propose a new method for PI-line choice and sampling grid, and a paralleled PI-line reconstruction algorithm implemented on NVIDIA's Compute Unified Device Architecture (CUDA). Numerical simulation studies are carried out to validate our method. Compared with conventional CPU implementation, the CUDA accelerated method provides images of the same quality with a speedup factor of 318. Optimization strategies for the GPU acceleration are presented. Finally, influence of the parameters of the PI-line samples on the reconstruction speed and image quality is discussed. (authors)

  16. Bubble-like appearances are characteristic thin-section CT findings of adenocarcinoma

    International Nuclear Information System (INIS)

    Kojima, Yoko; Saito, Haruhiro; Ito, Hiroyuki

    2008-01-01

    Adenocarcinomas are often diagnosed as old inflammatory lesions which are sometimes overlooked. Some of these adenocarcinomas display characteristic thin-section computed tomography (TS-CT) findings. We reported on these bubble-like appearances (BLA). We studied the BLA characteristics of adenocarcinomas. We reviewed the TS-CT findings of 17 (6 men, 11 women) cases of adenocarcinoma with bubble-like appearances. All 17 patients had undergone surgery between August 2003 and March 2007. We studied correlations between the TS-CT findings, the pathological findings and the clinical characteristics. The average tumor diameter was 35.4 mm. The definition of BLA is; having a irregular shape with straight margins, peripheral ground-glass opacity (GGO), dilated air bronchograms (more than 3), prominent pleural indentation. The pathological characteristics of tumors with BLA were; peripheral bronchioloalveolar cell carcinoma (BAC) patterns, almost total collapse (about 80% of the tumor area), and several ectatic small bronchi. Six cases were initially overlooked, because the TS-CT findings appeared as old inflammation. The average tumor doubling time was 1167 days. After resection, there have been no recurrences. On TS-CT images, BLA type adenocarcinomas appear as irregular in shape and they have a very slow doubling time. These types of lesions require careful attention because they are often diagnosed as old inflammatory scarring. (author)

  17. Appearance of the aging pancreas on CT scans: Implications in diagnosis of pancreatic carcinoma

    International Nuclear Information System (INIS)

    Mattison, G.R.; Francis, I.R.; Glazer, G.M.; Trenkner, S.W.

    1986-01-01

    Because early pancreatic cancer may not appear on CT as a frank mass, the CT-based diagnosis relies on detection of subtle changes such as focal loss of lobulation or asymmetry in the distribution of tissue. The author studied the normal pancreas in 140 patients of different ages to determine if there is an overlap in the appearance of the normal aging pancreas and subtle signs of pancreatic cancer. Both contour lobulation and fatty infiltration were found to increase with age and involved the pancreatic body and tail more than the head. These normal age-related changes should be recognized to avoid overdiagnosing pancreatic head masses

  18. Ultrasound, CT and MRI Appearances of a Rare Symptomatic Laryngeal Chondrometaplasia: A Case Report

    International Nuclear Information System (INIS)

    Lee, Ryan Ka Lok; Hok Yuen, Edmond Yuen; Abdullah, Victor James; Ping Lee, Yolanda Yim; Ahuja, Anil Tejbhan

    2015-01-01

    Symptomatic laryngeal chondrometaplasia is rare. To the best of our knowledge, there are only few case reports on laryngeal chondrometaplasia. The imaging appearance of this uncommon disease is even more rarely described. There are only two case reports describing its appearances in computed tomography (CT) and magnetic resonance imaging (MRI). Ultrasound (US) features have not been reported so far. This case report is to show the US, CT and MRI features of this disease entity to stress the role of imaging in this disease

  19. MR and CT imaging of pulmonary valved conduits in children and adolescents: normal appearance and complications

    Energy Technology Data Exchange (ETDEWEB)

    Tenisch, Estelle V.; Alamo, Leonor T.; Gudinchet, Francois [Lausanne University Hospital, Department of Medical Imaging, Lausanne (Switzerland); Sekarski, Nicole [Lausanne University Hospital, Department of Pediatrics, Lausanne (Switzerland); Hurni, Michel [Lausanne University Hospital, Department of Cardiovascular Surgery, Lausanne (Switzerland)

    2014-12-15

    The Contegra registered is a conduit made from the bovine jugular vein and then interposed between the right ventricle and the pulmonary artery. It is used for cardiac malformations in the reconstruction of right ventricular outflow tract. To describe both normal and pathological appearances of the Contegra registered in radiological imaging, to describe imaging of complications and to define the role of CT and MRI in postoperative follow-up. Forty-three examinations of 24 patients (17 boys and 7 girls; mean age: 10.8 years old) with Contegra registered conduits were reviewed. Anatomical description and measurements of the conduits were performed. Pathological items examined included stenosis, dilatation, plicature or twist, thrombus or vegetations, calcifications and valvular regurgitation. Findings were correlated to the echographic gradient through the conduit when available. CT and MR work-up showed Contegra registered stenosis (n = 12), dilatation (n = 9) and plicature or twist (n = 7). CT displayed thrombus or vegetations in the Contegra registered in three clinically infected patients. Calcifications of the conduit were present at CT in 12 patients and valvular regurgitation in three patients. The comparison between CT and/or MR results showed a good correlation between the echographic gradient and the presence of stenosis in the Contegra registered. CT and MR bring additional information about permeability and postoperative anatomy especially when echocardiography is inconclusive. Both techniques depict the normal appearance of the conduit, and allow comparison and precise evaluation of changes in the postoperative follow-up. (orig.)

  20. Diagnosis of deep vein thrombosis using multi-detector helical CT

    Energy Technology Data Exchange (ETDEWEB)

    Kimura, Masashi; Minamiguchi, Hiroki; Sahara, Shinya [Wakayama Medical Coll. (Japan)] [and others

    2002-11-01

    The purpose of this study was to evaluate the usefulness of multi-detector helical CT (MDHCT) with contrast medium in the diagnosis of deep vein thrombosis (DVT). The bilateral veins of the dorsal pedis in 45 patients (12 men, 33 women; average age, 64 years) under clinical suspicion of DVT were first punctured using 22-G needles. Then CT scanning from the level of the foot to the inferior vena cava was started 20 sec after the initial injection of 200 mL of dilute contrast medium (50 mL nonionic iodinated contrast medium of 300 mgI/mL and 150 mL saline) at a rate of 5 mL/sec. Two patients were excluded because of unsuccessful venous puncture. The average scanning time in 43 patients was 38.5{+-}7.9 seconds. Images of veins from the foot to the inferior vena cava were clearly demonstrated in each case. MDHCT showed DVT in 32 cases and patent deep vein in 11 cases. Simultaneous venography of the lower extremity in 18 patients clearly visualized DVT at the same level detected by contrast MDHCT. MDHCT for the diagnosis of DVT has the advantages of wider scanning rage, shorter scanning time, and finer Z-axis resolution than the other diagnostic modalities. (author)

  1. Diagnosis of deep vein thrombosis using multi-detector helical CT

    International Nuclear Information System (INIS)

    Kimura, Masashi; Minamiguchi, Hiroki; Sahara, Shinya

    2002-01-01

    The purpose of this study was to evaluate the usefulness of multi-detector helical CT (MDHCT) with contrast medium in the diagnosis of deep vein thrombosis (DVT). The bilateral veins of the dorsal pedis in 45 patients (12 men, 33 women; average age, 64 years) under clinical suspicion of DVT were first punctured using 22-G needles. Then CT scanning from the level of the foot to the inferior vena cava was started 20 sec after the initial injection of 200 mL of dilute contrast medium (50 mL nonionic iodinated contrast medium of 300 mgI/mL and 150 mL saline) at a rate of 5 mL/sec. Two patients were excluded because of unsuccessful venous puncture. The average scanning time in 43 patients was 38.5±7.9 seconds. Images of veins from the foot to the inferior vena cava were clearly demonstrated in each case. MDHCT showed DVT in 32 cases and patent deep vein in 11 cases. Simultaneous venography of the lower extremity in 18 patients clearly visualized DVT at the same level detected by contrast MDHCT. MDHCT for the diagnosis of DVT has the advantages of wider scanning rage, shorter scanning time, and finer Z-axis resolution than the other diagnostic modalities. (author)

  2. The utility of helical CT in assessing the frequency of ureterolithiasis in Saudi patients

    International Nuclear Information System (INIS)

    Al-Nakshabandi, Nizar A.; Zayed, Mohamed A.; Elsharkaway, Mohamed S.; Al-Boukai, Ahmad S.; Al-Omar, M.

    2008-01-01

    Objective was to identify 650 patients who underwent Ct for renal colic and review them for age and gender in Saudi Arabia. Scans were performed on a 16 multislice scanner. A total of 650 patients with the clinical suspicion of ureteric colic were reviewed; 220 females (33.8%) and 430 males (66.2%), with a female to male ratio of 1:2. Examinations were carried out from January 2005 to November 2006, at King Khalid University Hospital, Riyadh, Kingdom of Saudi Arabia. Three hundred and ninety five patients out of 650 had stones; 2 of 395 (0.5%) had stones in the 5-15 years age group, 28 (7.%) in the 16-25 years age group, 99 (25.1%) in the 26-35 years, 106 (26.8%) in the 36-45 age group, 84 (21.9%) in the 46-55 age group, 51 (12.9%) in the 56-65 age group, and 25 (6.3%) in the above 66 years age group. The most significant finding in our study is that as the patients age increases so does the percentage of stones up to the age of 56, with a peak at age group of 26-35 where stone percentage reaches 26.8%. Unenhanced helical CT is useful for the diagnosis of ureterolithiasis. (author)

  3. Stochastic field line structures appearing in field line tracing calculations for a helical magnetic limiter on TORE SUPRA

    International Nuclear Information System (INIS)

    Fuchs, G.; Steffen, B.; Blenski, T.; Grosman, A.; Samain, A.

    1985-05-01

    The influence on the structure of the magnetic field of a tokamak produced by small helical currents flowing near the plasma in TORE SUPRA was investigated numerically by drawing Poincare plots. The current in the helical conductors, the pitch of the windings, the rotational transform and the plasma pressure have been varied. The topology of the magnetic field line structure is discussed in some detail and simple examples are given for illustration. (orig.)

  4. Usefulness of multiplanar reformatted images of multi-detector row helical CT in assessment of biliary stent patency

    International Nuclear Information System (INIS)

    Kim, Soo Jin; Kim, Suk; Kim, Chang Won; Lee, Jun Woo; Lee, Tae Hong; Choo, Ki Seok; Koo, Young Baek; Moon, Tae Yong; Lee, Suk Hong

    2004-01-01

    To evaluate the usefulness of multi-detector row helical CT (MDCT), multiplanar reformatted images for the noninvasive assessment of biliary stent patency, and for the planning for management in patients with a sele-expandable metallic stent due to malignant biliary obstruction. Among 90 consecutive patients, from August 1999 to July 2003, 26 cases in 23 patients with malignant biliary obstruction who underwent self-expandable metaIlic stent insertion in the biliary system and percutaneous transhepatic biliary drainage within 7 days after CT were enrolled in this study. On CT images, the complete and functional obstruction of the stent and the precise level of obstruction were evaluated. The presence of an enhancing intraluminal mass or wall thickening around stent was determined, and the causes of obstruction were evaluated. These findings were then compared with percutaneous transhepatic cholangiography. Multi-detector row helical CT correctly demonstrated the patency of a stent in 24 cases (92.3%). It was adequate in helping to depict the precise level of stent occlusion in 23 cases (88.5%). Multi-detector row helical CT also revealed the extent of tumor that represented as an enhancing intraluminal mass or wall thickening around the stent in 23 cases, and this was represented as complete obstruction on percutaneous transhepatic cholangiography. In the case of functional obstruction, MDCT predicted the possible cause of the obstruction. Multiplanar reformatted images of multi-detector row helical CT is a useful imaging modality for the noninvasive assessment of stent patency and the precise level of obstruction when stent obstruction is suspected in the patients with self-expandable metallic stent due to malignant biliary obstruction. It can also predict the possible cause of the obstruction and allows adequate planning for the medical management of such cases

  5. Usefulness of multiplanar reformatted images of multi-detector row helical CT in assessment of biliary stent patency

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Soo Jin; Kim, Suk; Kim, Chang Won; Lee, Jun Woo; Lee, Tae Hong; Choo, Ki Seok; Koo, Young Baek; Moon, Tae Yong; Lee, Suk Hong [Pusan National Univ. Hospital, Busan (Korea, Republic of)

    2004-08-01

    To evaluate the usefulness of multi-detector row helical CT (MDCT), multiplanar reformatted images for the noninvasive assessment of biliary stent patency, and for the planning for management in patients with a sele-expandable metallic stent due to malignant biliary obstruction. Among 90 consecutive patients, from August 1999 to July 2003, 26 cases in 23 patients with malignant biliary obstruction who underwent self-expandable metaIlic stent insertion in the biliary system and percutaneous transhepatic biliary drainage within 7 days after CT were enrolled in this study. On CT images, the complete and functional obstruction of the stent and the precise level of obstruction were evaluated. The presence of an enhancing intraluminal mass or wall thickening around stent was determined, and the causes of obstruction were evaluated. These findings were then compared with percutaneous transhepatic cholangiography. Multi-detector row helical CT correctly demonstrated the patency of a stent in 24 cases (92.3%). It was adequate in helping to depict the precise level of stent occlusion in 23 cases (88.5%). Multi-detector row helical CT also revealed the extent of tumor that represented as an enhancing intraluminal mass or wall thickening around the stent in 23 cases, and this was represented as complete obstruction on percutaneous transhepatic cholangiography. In the case of functional obstruction, MDCT predicted the possible cause of the obstruction. Multiplanar reformatted images of multi-detector row helical CT is a useful imaging modality for the noninvasive assessment of stent patency and the precise level of obstruction when stent obstruction is suspected in the patients with self-expandable metallic stent due to malignant biliary obstruction. It can also predict the possible cause of the obstruction and allows adequate planning for the medical management of such cases.

  6. Sacral pseudotumor complicating iliac bone harvest: radiographic, CT and MRI appearances

    Energy Technology Data Exchange (ETDEWEB)

    Kavanagh, E.; Roth, C.; O' Connell, M.; Eustace, S. [Dept. of Radiology, Mater Misericordiae Hospital, Dublin (Ireland)

    2003-12-01

    We present the imaging appearances of a lytic pseudotumor in the right sacral ala presenting with referred pain to the right thigh. Subsequent imaging revealed the presence of a cystic lesion arising at the site of previous bone graft harvest; CT-guided aspiration yielded synovial fluid presumed to arise from the contiguous sacroiliac joint. (orig.)

  7. Role of contrast-enhanced helical CT in the evaluation of acute thoracic aortic injuries after blunt chest trauma

    International Nuclear Information System (INIS)

    Scaglione, M.; Pinto, A.; Pinto, F.; Romano, L.; Ragozzino, A.; Grassi, R.

    2001-01-01

    The purpose of this retrospective study was to determine the value of contrast-enhanced helical CT for detecting and managing acute thoracic aortic injury (ATAI). Between June 1995 and February 2000, 1419 consecutive chest CT examinations were performed in the setting of major blunt trauma. The following CT findings were considered indicative of ATAI: intimal flap; pseudoaneurysm; contour irregularity; lumen abnormality; and extravasation of contrast material. On the basis of these direct findings no further diagnostic investigations were performed. Isolated mediastinal hematoma on CT scans was considered an indirect sign of ATAI: In these cases, thoracic aortography was performed even if CT indicated normal aorta. Seventy-seven patients had abnormal CT scans: Among the 23 patients with direct CT signs, acute thoracic aortic injuries was confirmed at thoracotomy in 21. Two false-positive cases were observed. The 54 remaining patients had isolated mediastinal hematoma without aortic injuries at CT and corresponding negative angiograms. The 1342 patients with negative CT scans were included in the 8-month follow-up program and did not show any adverse sequela based on clinical and radiographic criteria. Contrast-enhanced helical CT has a critical role in the exclusion of thoracic aortic injuries in patient with major blunt chest trauma and prevents unnecessary thoracic aortography. Direct CT signs of ATAI do not require further diagnostic investigations to confirm the diagnosis: Isolated aortic bands or contour vessel abnormalities should be first considered as possible artifacts or related to non-traumatic etiologies especially when mediastinal hematoma is absent. In cases of isolated mediastinal hematoma other possible sources of bleeding should be considered before directing patients to thoracic aortography. (orig.)

  8. Anticlockwise swirl of mesenteric vessels: A normal CT appearance, retrospective analysis of 200 pediatric patients

    Energy Technology Data Exchange (ETDEWEB)

    Sodhi, Kushaljit S., E-mail: sodhiks@gmail.com [Department of Radiodiagnosis and Imaging, Post Graduate Institute of Medical Education and Research, Sector-12, Chandigarh 160012 (India); Bhatia, Anmol, E-mail: anmol_bhatia26@yahoo.co.in [Department of Radiodiagnosis and Imaging, Post Graduate Institute of Medical Education and Research, Sector-12, Chandigarh 160012 (India); Saxena, Akshay K., E-mail: fatakshay@yahoo.com [Department of Radiodiagnosis and Imaging, Post Graduate Institute of Medical Education and Research, Sector-12, Chandigarh 160012 (India); Rao, Katragadda L.N., E-mail: klnrao@hotmail.com [Department of Pediatric Surgery, Post Graduate Institute of Medical Education and Research, Sector-12, Chandigarh 160012 (India); Menon, Prema, E-mail: menonprema@hotmail.com [Department of Pediatric Surgery, Post Graduate Institute of Medical Education and Research, Sector-12, Chandigarh 160012 (India); Khandelwal, Niranjan, E-mail: khandelwaln@hotmail.com [Department of Radiodiagnosis and Imaging, Post Graduate Institute of Medical Education and Research, Sector-12, Chandigarh 160012 (India)

    2014-04-15

    Objective: The counterclockwise rotation of the SMV on SMA is a normal and non-specific finding, which results in an incomplete swirl formation on CT scans. However, it has a potential to be misinterpreted as ‘midgut volvulus’ resulting in serious clinical implications. The study was done to determine the frequency and degree of counterclockwise rotation of the SMV on SMA on CT in normal otherwise asymptomatic pediatric patients undergoing CT scan. Methods: In this IRB approved study, we retrospectively analyzed abdominal CT scan examinations of 200 consecutive pediatric patients (age range of 11 days to 18 years), which were performed for different clinical indications over a period of 10 months. They were evaluated for the absence or presence and degree of counterclockwise rotation of the mesenteric vessels. Results: Of the 200 patients, 128 (64%) patients showed no clockwise or anticlockwise rotation of mesenteric vessels. Counterclockwise rotation of SMV on SMA was seen in 72 (36%) patients. Further, the degree of rotation of vessels was also calculated, based on the criteria proposed by the authors. Conclusions: The counterclockwise rotation of SMV on SMA gives an appearance of mesenteric whirlpool in otherwise normal mesenteric vessels and can be misinterpreted as midgut volvulus. It is a normal CT appearance and is due to a variation in branching pattern of mesenteric vessels. Awareness of this normal branching pattern of mesenteric vessels is important to avoid an inadvertent laparotomy.

  9. Anticlockwise swirl of mesenteric vessels: A normal CT appearance, retrospective analysis of 200 pediatric patients

    International Nuclear Information System (INIS)

    Sodhi, Kushaljit S.; Bhatia, Anmol; Saxena, Akshay K.; Rao, Katragadda L.N.; Menon, Prema; Khandelwal, Niranjan

    2014-01-01

    Objective: The counterclockwise rotation of the SMV on SMA is a normal and non-specific finding, which results in an incomplete swirl formation on CT scans. However, it has a potential to be misinterpreted as ‘midgut volvulus’ resulting in serious clinical implications. The study was done to determine the frequency and degree of counterclockwise rotation of the SMV on SMA on CT in normal otherwise asymptomatic pediatric patients undergoing CT scan. Methods: In this IRB approved study, we retrospectively analyzed abdominal CT scan examinations of 200 consecutive pediatric patients (age range of 11 days to 18 years), which were performed for different clinical indications over a period of 10 months. They were evaluated for the absence or presence and degree of counterclockwise rotation of the mesenteric vessels. Results: Of the 200 patients, 128 (64%) patients showed no clockwise or anticlockwise rotation of mesenteric vessels. Counterclockwise rotation of SMV on SMA was seen in 72 (36%) patients. Further, the degree of rotation of vessels was also calculated, based on the criteria proposed by the authors. Conclusions: The counterclockwise rotation of SMV on SMA gives an appearance of mesenteric whirlpool in otherwise normal mesenteric vessels and can be misinterpreted as midgut volvulus. It is a normal CT appearance and is due to a variation in branching pattern of mesenteric vessels. Awareness of this normal branching pattern of mesenteric vessels is important to avoid an inadvertent laparotomy

  10. Dynamic evaluation of pelvic floor reconstructive surgery using radiopaque meshes and three-dimensional helical CT

    Directory of Open Access Journals (Sweden)

    Paulo Palma

    2010-04-01

    Full Text Available PURPOSE: This prospective study was performed to achieve visualization of the reestablishment of anatomy after reconstructive surgery in the different pelvic compartments with non-absorbable radiopaque meshes, providing valuable anatomic information for surgeons implanting meshes. MATERIALS AND METHODS: A total of 30 female patients with stress urinary incontinence (SUI, anterior and posterior vaginal wall prolapse, or both underwent surgical repair using radiopaque meshes after written informed consent. Patients with SUI underwent five different surgeries. Patients with anterior vaginal prolapse underwent a procedure using a combined pre-pubic and transobturator mesh, and those with posterior vaginal prolapse underwent posterior slingplasty. Three-dimensional reconstruction using helical CT was performed four weeks postoperatively. RESULTS: In all cases, the mesh was clearly visualized. Transobturator slings were shown at the midurethra, and the anchoring tails perforated the obturator foramen at the safety region. Mini-slings were in the proper place, and computed angiography revealed that the anchoring system was away from the obturator vessels. In patients undergoing procedure for anterior vaginal prolapse, both pre-pubic armpit and obturator slings were clearly seen and the mesh was in the proper position, supporting the bladder base and occluding the distal part of the urogenital hiatus. Transcoccygeal sacropexy revealed indirectly a well-supported "neo rectovaginal fascia" and the anchoring tails at the level of ischial spines. CONCLUSION: Three-dimensional helical tomography images of the female pelvis using radiopaque meshes have a potential role in improving our understanding of pelvic floor reconstructive surgeries. These radiopaque meshes might be the basis of a new investigative methodology.

  11. Bone changes in the condylar head and mandibular fossa in patients with temporomandibular disorders. Helical CT observation

    International Nuclear Information System (INIS)

    Shimahara, Satoru; Ariyoshi, Yasunori; Kimura, Yoshihiro; Shimahara, Masashi

    2011-01-01

    In the present study, we investigated whether bone changes are present in sites impossible to observe by panoramic X-ray and Schuller's X-ray examination, namely the medial of the condylar head and mandibular fossa, in patients with type IV temporomandibular joint disorders. We observed the articular fossa using computed tomography, which is able to obtain detailed 3-dimensional information, in patients with type IV temporomandibular disorders. We examined 120 joints of 60 patiens who visited the Department of Oral Surgery, Osaka Medical College Hospital. Each condylar head was clearly visualized in panoramic X-ray and Schuller's X-ray examination findings, and shown to have possible changes unilaterally. Each joint was diagnosed as type IV, according to the diagnostic guidelines set by Japanese Society for Temporomandibular Joint, and further examined using helical CT. Changes in condylar head; We concluded that bone changes were present with considerable probability in the medial of condylar head in a manner similar to those found in the lateral and center of joints with type IV temporomandibular disorders. Changes in mandibular fossa; The bone changes occurred in various locations of the mandibular fossa, while they appeared significantly more frequently in the condylar head. We think that our finding will contribute to development of treatment strategies for temporomandibular disorders, as they clarify bone changes in sites previously unreported. (author)

  12. Metastatic liver tumor from cystic ovarian carcinomas. CT and MRI appearance

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Yi; Yamashita, Yasuyuki; Ogata, Ichiro; Namimoto, Tomohiro; Abe, Yasuko; Urata, Joji; Takahashi, Mutsumasa [Kumamoto Univ. (Japan). School of Medicine

    1999-08-01

    The initial and follow-up CT and MRI images of ten patients with hepatic metastases from ovarian tumors were retrospectively analyzed to establish their features and sequential changes in appearance. Ten patients with hepatic metastasis from ovarian tumors received initial and follow-up CT and MRI examinations. Six patients were followed up every two to three weeks before surgical tumor resection. Both CT and MR images were analyzed by two radiologists. A total of fourteen lesions were detected by CT and MRI in 10 patients. All 14 lesions were demonstrated as areas of marked hyperintensity on T2-weighted MRI. Eleven cyst-like tumors were demonstrated as round or oval low density lesions on CT and as areas of hypointensity on T1-weighted imaging. Three lesions were shown as solid masses with slightly low attenuation at the initial CT examination and slightly low or iso-intensity areas on T1-weighted imaging, and these lesions showed early peripheral globular enhancement and delayed enhancement on contrast-enhanced CT and MR imaging. Cystic formation was observed two to three weeks later after initial study in all the 3 solid lesions. Rapid subcapsular effusion, which showed obvious enhancement on delayed Gd-DTPA enhanced MR imaging, was observed in two patients. The hepatic metastatic tumor from cystic ovarian carcinoma may manifest as a well-defined cystic lesion or as a solid mass, and the solid mass shows delayed enhancement on contrast-enhanced CT and MR imaging. Furthermore, rapid cystic formation and rapid subcapsular extension is frequently seen. (author)

  13. Prospectively ECG-triggered sequential dual-source coronary CT angiography in patients with atrial fibrillation: comparison with retrospectively ECG-gated helical CT

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Lei; Yang, Lin; Zhang, Zhaoqi [Capital Medical University, Department of Radiology, Beijing Anzhen Hospital, Beijing (China); Wang, Yining; Jin, Zhengyu [Chinese Academy of Medical Sciences, Department of Radiology, Peking Union Medical College Hospital, Beijing (China); Zhang, Longjiang; Lu, Guangming [Nanjing University, Department of Medical Imaging, Jinling Hospital, Clinical School of Medical College, Nanjing, Jiangsu (China)

    2013-07-15

    To investigate the feasibility of applying prospectively ECG-triggered sequential coronary CT angiography (CCTA) to patients with atrial fibrillation (AF) and evaluate the image quality and radiation dose compared with a retrospectively ECG-gated helical protocol. 100 patients with persistent AF were enrolled. Fifty patients were randomly assigned to a prospective protocol and the other patients to a retrospective protocol using a second-generation dual-source CT (DS-CT). Image quality was evaluated using a four-point grading scale (1 = excellent, 2 = good, 3 = moderate, 4 = poor) by two reviewers on a per-segment basis. The coronary artery segments were considered non-diagnostic with a quality score of 4. The radiation dose was evaluated. Diagnostic segment rate in the prospective group was 99.4 % (642/646 segments), while that in the retrospective group was 96.5 % (604/626 segments) (P < 0.001). Effective dose was 4.29 {+-} 1.86 and 11.95 {+-} 5.34 mSv for each of the two protocols (P < 0.001), which was a 64 % reduction in the radiation dose for prospective sequential imaging compared with retrospective helical imaging. In AF patients, prospectively ECG-triggered sequential CCTA is feasible using second-generation DS-CT and can decrease >60 % radiation exposure compared with retrospectively ECG-gated helical imaging while improving diagnostic image quality. (orig.)

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

    Energy Technology Data Exchange (ETDEWEB)

    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.)

  15. Abdomen after a Puestow procedure: postoperative CT appearance, complications, and potential pitfalls.

    Science.gov (United States)

    Freed, K S; Paulson, E K; Frederick, M G; Keogan, M T; Pappas, T N

    1997-06-01

    To evaluate the postoperative computed tomographic (CT) appearance, complications, and potential pitfalls after a Puestow procedure (lateral side-to-side pancreaticojejunostomy). Forty CT examinations were performed after the Puestow procedure in 20 patients. Images were retrospectively reviewed by three radiologists. The pancreaticojejunal anastomosis was identified at 30 examinations and was immediately anterior to the pancreatic body or tail. The anastomosis contained fluid or gas on 11 scans and oral contrast material on four scans. On 15 scans, the anastomosis appeared as collapsed bowel without gas, fluid, or oral contrast material. The Roux-en-Y loop was identified on 28 (70%) scans and contained fluid or gas on 16 scans and oral contrast material on six scans. The Roux-en-Y loop appeared as collapsed bowel on six scans. When the anastomosis or Roux-en-Y loop contained fluid and gas, the appearance mimicked that of a pancreatic or parapancreatic abscess. Peripancreatic stranding was present on 28 scans and was due to either ongoing pancreatitis or postoperative change. Complications included 15 transient fluid collections, three abscesses, four pseudocysts, one hematoma, and one small-bowel and Roux-en-Y obstruction. Knowledge of the anatomy after a Puestow procedure is essential for accurate interpretation of CT scans.

  16. Multislice Helical CT Angiography in Diagnostic of Intracranial and Extracranial Arterial Dissection

    International Nuclear Information System (INIS)

    Radzina, M.; Krumina, G.; Pupols, J.

    2007-01-01

    complete information about arterial extracranial and intracranial vascular system. CTA is highly informative in characterization of dissection site and morphology, also diagnostic of combined brain pathology. Appropriate quality CTA requires high capacity: at least 16 slice helical CT equipment that provides quick examination with wide range of post processing possibilities. Non enhanced brain CT is recommended before CTA, to specify cerebral structural changes and to identify vascular calcified plaques. Indications for intracranial CTA: subarachnoidal hemorrhage, intracerebral hematoma, intraventricular hemorrhage, cerebral infarction; outpatient praxis: stenoses, aneurysms, arteriovenous malformations, cerebral infarction history, vasculitis. Indications for brachiocephalic CTA are: acute head-neck trauma, ischemia; for outpatient praxis: US suspected vessel stenoses, cerebral infarction history. Selected protocol with post process ing opens up new opportunities for further research of most optimized CTA follow up time, evaluation of recanalization, and randomization of patients, angkalcinguldisekcija, for stenting procedures of dissected arterial segment. authors)

  17. Prospective comparison of helical CT with angiography in pulmonary embolism: global and selective vascular territory analysis. Interobserver agreement

    International Nuclear Information System (INIS)

    Ruiz, Yolanda; Caballero, Paloma; Caniego, Jose Luis; Friera, Alfonsa; Olivera, Maria Jose; Tagarro, David; Alvarez-Sala, Rodolfo

    2003-01-01

    The objective of this prospective study was to evaluate the sensitivity, specificity, positive and negative predictive values, and interobserver agreement in the diagnosis of pulmonary embolism with helical CT, compared with pulmonary angiography, for both global results and for selective vascular territories. Helical CT and pulmonary angiography were performed on 66 consecutive patients with clinical suspicion of pulmonary embolism. The exams were blindly interpreted by a vascular radiologist and by two independent thoracic radiologists. Results were analyzed for the final diagnosis as well as separately for 20 different arterial territories in each patient. Pulmonary angiography revealed embolism in 25 patients (38%); 48% were main, 28% lobar, 16% segmental, and 8% subsegmental. The sensitivity, specificity, and positive and negative predictive values of helical CT for observer 1 were, respectively, 91, 81.5, 75, and 94%; in 7.5% of the patients the exam was considered indeterminate. For observer 2 the values were, respectively, 88, 86, 81.5, and 91%; in 9% of the patients the exam was considered indeterminate. Main arteries were considered as non-valuable in 0-0.8%, the lobar in 1.5%, the segmental in 7.5-8.5%, and the subsegmental in 55-60%. Interobserver agreement for the final diagnosis was 80% (kappa 0.65). For each vascular territory, this was 98% (kappa 0.91) for main arteries, 92% (kappa 0.78) for lobar arteries, 79% (kappa 0.56) for segmental arteries, and 59% (kappa 0.21) for subsegmental arteries. Helical CT is a reliable method for pulmonary embolism diagnosis, with good interobserver agreement for main, lobar, and segmental territories. Worse results are found for subsegmental arteries, with high incidence of non-valuable branches and poor interobserver agreement. (orig.)

  18. Clinical applications for multiplanar- and three-dimensional-reconstructions by helical-CT for the diagnosis of acetabular fractures

    International Nuclear Information System (INIS)

    Stroszczynski, C.; Schedel, H.; Stoeckle, U.; Wellmann, A.; Beier, J.; Wicht, L.; Hoffmann, R.; Felix, R.

    1996-01-01

    This review describes recent visualizations of computed tomography for the diagnosis of acetabular fractures. The techniques of conventional and helical-CT for the imaging of the acetabulum are compared. Furthermore, the different methods of multiplaner and three-dimensional reconstructions e.g. shaded surface display, maximum intensity projection, and volume rendering are presented. Figures of multiplanar and three-dimensional imaging for fractures of the pelvis is discussed. (orig.) [de

  19. Chronic intestinal pseudo-obstruction in adult patients: multidetector row helical CT features

    International Nuclear Information System (INIS)

    Merlin, Aurelie; Soyer, Philippe; Boudiaf, Mourad; Hamzi, Lounis; Rymer, Roland

    2008-01-01

    Chronic intestinal pseudo-obstruction (CIPO) is a rare condition due to severe gastrointestinal motility disorder. Adult patients with CIPO experience symptoms of mechanical obstruction, but reliable clinical signs that may help distinguish between actual mechanical obstruction and CIPO are lacking. Additionally, abdominal plain films that commonly show bowel dilatation with air-fluid levels do not reach acceptable degrees of specificity to exclude actual obstruction. Therefore, most adult patients with CIPO usually undergo multiple and often fruitless surgery, often leading to repeated bowel resections before diagnosis is made. In these patients who present with abdominal signs mimicking symptoms that would warrant surgical exploration, multidetector-row helical CT (MDCT) is helpful to resolve this diagnostic dilemma. MDCT shows a diffusely distended bowel and helps to rule out a mechanical cause of obstruction, thus suggesting CIPO and obviating the need for unnecessary laparotomy. In adult patients with CIPO, MDCT may show pneumatosis intestinalis, pneumoperitoneum or intussusception. However, these conditions generally do not require surgery in patients with CIPO. This pictorial essay presents the more and less common MDCT features of CIPO in adult patients, to make the reader more familiar with this disease. (orig.)

  20. Multislice helical CT (MSCT) for mid-facial trauma: optimization of parameters for scanning and reconstruction

    International Nuclear Information System (INIS)

    Dammert, S.; Funke, M.; Obernauer, S.; Grabbe, E.; Merten, H.A.

    2002-01-01

    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.) [de

  1. Diagnosis of nutcracker syndrome of the left renal vein. Value of the corticomedullary phase of helical CT

    International Nuclear Information System (INIS)

    Igari, Hidenori

    2001-01-01

    The clinical significance of the corticomedullary phase of helical CT in the diagnosis of nutcracker syndrome of the left renal vein (LRV) was evaluated. A total of 38 patients with hematuria of unknown origin (12 men and 26 women, mean age 24 years [range: 18-32 years]) were examined by helical CT of the kidneys, retrograde left renal venography, and measurement of renocaval pressure gradients. The sensitivity and specificity of the corticomedullary and nephrographic phases of helical CT for detecting the nutcracker syndrome were determined. The nutcracker syndrome was diagnosed on the basis of the renography findings combined with pressure measurements in 19 patients: 12 with LRV hypertension and collateral veins, 1 with hypertension and no collateral veins, and 6 with collateral veins and normal pressure gradients or borderline hypertension. Both the corticomedullary- and nephrographic-phase images revealed distended LRVs in 26 (68%) of the 38 patients. The LRV mean attenuation values in the corticomedullary phase (164±22 Hounsfield units [H], range: 138-209 H) was significantly greater (p<0.001) than in the nephrographic phase (80±14 H, range: 62-100 H). During the corticomedullary phase, opacified blood from the renal vein was mixed with unopacified blood in the IVC. In the nephrographic phase, however, the IVC was enhanced homogeneously, but only slightly. Corticomedullary-phase imaging detected collateral veins that exhibited early enhancement, indicating retrograde flow from the LRVs in 15 out of 18 patients (83% of those with collateral veins), while the nephrographic-phase imaging revealed collateral veins in 8 patients (44% of those with collateral veins). The sensitivity and specificity of the corticomedullary-phase scan for detecting the nutcracker syndrome were 79% and 100%, respectively, as opposed to 42% and 100%, respectively, for the nephrographic phase. Retrograde flow from the LRV into the collateral veins in the corticomedullary phase is a

  2. Effect of CT contrast on volumetric arc therapy planning (RapidArc and helical tomotherapy) for head and neck cancer

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Alan J.; Vora, Nayana [Department of Radiation Oncology, City of Hope National Medical Center, Duarte, CA (United States); Suh, Steve [Department of Radiation Physics, City of Hope National Medical Center, Duarte, CA (United States); Liu, An, E-mail: aliu@coh.org [Department of Radiation Physics, City of Hope National Medical Center, Duarte, CA (United States); Schultheiss, Timothy E. [Department of Radiation Physics, City of Hope National Medical Center, Duarte, CA (United States); Wong, Jeffrey Y.C. [Department of Radiation Oncology, City of Hope National Medical Center, Duarte, CA (United States)

    2015-04-01

    The objectives of the study were to evaluate the effect of intravenous contrast in the dosimetry of helical tomotherapy and RapidArc treatment for head and neck cancer and determine if it is acceptable during the computed tomography (CT) simulation to acquire only CT with contrast for treatment planning of head and neck cancer. Overall, 5 patients with head and neck cancer (4 men and 1 woman) treated on helical tomotherapy were analyzed retrospectively. For each patient, 2 consecutive CT scans were performed. The first CT set was scanned before the contrast injection and secondary study set was scanned 45 seconds after contrast. The 2 CTs were autoregistered using the same Digital Imaging and Communications in Medicine coordinates. Tomotherapy and RapidArc plans were generated on 1 CT data set and subsequently copied to the second CT set. Dose calculation was performed, and dose difference was analyzed to evaluate the influence of intravenous contrast media. The dose matrix used for comparison included mean, minimum and maximum doses of planning target volume (PTV), PTV dose coverage, and V{sub 45} {sub Gy}, V{sub 30} {sub Gy}, and V{sub 20} {sub Gy} organ doses. Treatment planning on contrasted images generally showed a lower dose to both organs and target than plans on noncontrasted images. The doses for the points of interest placed in the organs and target rarely changed more than 2% in any patient. In conclusion, treatment planning using a contrasted image had insignificant effect on the dose to the organs and targets. In our opinion, only CT with contrast needs to be acquired during the CT simulation for head and neck cancer. Dose calculations performed on contrasted images can potentially underestimate the delivery dose slightly. However, the errors of planning on a contrasted image should not affect the result in clinically significant way.

  3. Helical CT for emergency patients with cerebrovascular diseases. Diagnosis of cerebral aneurysms with subarachnoid hemorrhage (SAH) by three-dimensional CT angiography (3D-CTA)

    International Nuclear Information System (INIS)

    Matsumoto, Masato; Satoh, Naoki; Kobayashi, Touru; Kodama, Namio; Nakano, Masayuki; Watanabe, Youichi; Fujii, Masayuki

    1996-01-01

    Recently, the usefulness of three-dimensional CT angiography (3D-CTA) using helical CT has been reported. Although 3D-CTA has been applied for neurosurgical diseases, especially for surgical planning, it has not done for emergency patients because of the long time required for image reconstruction and location of a helical CT scanner. We studied emergency patients with SAH, and compared the 3D-CTA with angiography and surgical findings, using TOSHIBA X vigor. Twenty-two patients with SAH were evaluated. The helical CT was performed for 55 seconds with a bolus injection of 90 ml non-ionic, iodinated contrast medium at a rate of 3 ml/sec with a delay of 20 sec. Angiography was carried out immediately after the helical CT. Eighteen of 22 cases were operated on urgently. We were able to create the 3D-CTA in about 7 minutes, and diagnose aneurysms by the 3D-CTA before angiography. The 3D-CTA was able to demonstrate 30 of 31 aneurysms including 9 unruptured aneurysms. An unruptured internal carotid-posterior communicating artery aneurysm 1.3 mm in diameter and associated with a ruptured aneurysm was not detected by either the 3D-CTA or angiography. On the other hand, an unruptured Acom aneurysm 0.8 mm in diameter and associated with a ruptured aneurysm could be detected by the: 3D-CTA, but not by angiography. The 3D-CTA gave us useful information concerning the anatomical relationship of the aneurysm, its neck and parent artery, and the surrounding branches. There were no complications or side effects associated with the helical CT scan. Although the 3D-CTA requires further development of visualization of small arteries less than 1 mm in diameter, such as perforating arteries, subtraction technique of bony structure, and a method for checking cervical arteries, it is useful for diagnosis of emergency patients with SAH and urgent operations. We believe that an operation might be performed by only the 3D-CTA without the angiography in the near future. (author)

  4. Helical CT for emergency patients with cerebrovascular diseases. Diagnosis of cerebral aneurysms with subarachnoid hemorrhage (SAH) by three-dimensional CT angiography (3D-CTA)

    Energy Technology Data Exchange (ETDEWEB)

    Matsumoto, Masato; Satoh, Naoki; Kobayashi, Touru; Kodama, Namio; Nakano, Masayuki; Watanabe, Youichi; Fujii, Masayuki [Fukushima Medical School (Japan)

    1996-05-01

    Recently, the usefulness of three-dimensional CT angiography (3D-CTA) using helical CT has been reported. Although 3D-CTA has been applied for neurosurgical diseases, especially for surgical planning, it has not done for emergency patients because of the long time required for image reconstruction and location of a helical CT scanner. We studied emergency patients with SAH, and compared the 3D-CTA with angiography and surgical findings, using TOSHIBA X vigor. Twenty-two patients with SAH were evaluated. The helical CT was performed for 55 seconds with a bolus injection of 90 ml non-ionic, iodinated contrast medium at a rate of 3 ml/sec with a delay of 20 sec. Angiography was carried out immediately after the helical CT. Eighteen of 22 cases were operated on urgently. We were able to create the 3D-CTA in about 7 minutes, and diagnose aneurysms by the 3D-CTA before angiography. The 3D-CTA was able to demonstrate 30 of 31 aneurysms including 9 unruptured aneurysms. An unruptured internal carotid-posterior communicating artery aneurysm 1.3 mm in diameter and associated with a ruptured aneurysm was not detected by either the 3D-CTA or angiography. On the other hand, an unruptured Acom aneurysm 0.8 mm in diameter and associated with a ruptured aneurysm could be detected by the: 3D-CTA, but not by angiography. The 3D-CTA gave us useful information concerning the anatomical relationship of the aneurysm, its neck and parent artery, and the surrounding branches. There were no complications or side effects associated with the helical CT scan. Although the 3D-CTA requires further development of visualization of small arteries less than 1 mm in diameter, such as perforating arteries, subtraction technique of bony structure, and a method for checking cervical arteries, it is useful for diagnosis of emergency patients with SAH and urgent operations. We believe that an operation might be performed by only the 3D-CTA without the angiography in the near future. (author)

  5. Dynamic contrast-enhanced CT appearances of the intraductal papillary neoplasms of the bile duct

    International Nuclear Information System (INIS)

    Song Fengxiang; Zhou Jianjun; Zeng Mengsu; Zhou Kangrong; Ding Yuqin; He Deming; Shi Yuxin; Zhou Jun

    2013-01-01

    Objective: To analyze the dynamic contrast-enhanced CT appearances of intraductal papillary neoplasms of the bile duct and improve its diagnostic accuracy. Methods: Sixteen patients with intraductal papillary neoplasms of the bile duct confirmed histopathologically after surgical operation underwent dynamic contrast-enhanced multi-detector row CT scans. All imaging data were reviewed and analyzed retrospectively in correlation with surgical and pathological findings. CT values of 38 well-visualized lesions in 12 of the 16 patients at the pre-contrast phase, arterial phase and venous phase were measured. Four of the 12 patients with 17 lesions had benign tumors, and 8 of the 12 patients with 21 lesions had malignant tumors. Comparisons of CT values at the three phases between the two groups were carried out using independent sample t test. The bile CT values were measured in these 12 cases, 40 normal volunteers, and 40 subjects with bile duct stones, and the Wilcoxon signed-rank test was applied to compare the bile CT values between tumor group and the normal group and between tumor group and the bile duct stone group. The diameters of the bile ducts proximal to and distal to tumors were also measured, and Fisher exact method was carried to analyze the data. Results: Lesions located at the left lobe in 8 out of the 16 patients, the right lobe in 1 case, both the left and right lobes in 1 case, the hepatic hilum in 1 case, the common bile duct in 3 cases, and both the right lobe and the common bile duct in 2 cases. Eleven lesions appeared as papillary masses, 3 as flat masses, 1 as mixed papillary and flat masses. In one case, tumor mass could not be definitely visualized, and only dilated bile ducts and stones were demonstrated. The mean CT values of the benign tumors were (25.8 ± 8.0), (37.7 ± 10.3) and (51.7 ± 17.1) HU respectively at pre-contrast phase, arterial phase, and venous phase, and the malignant tumors were (38.4 ± 10.2), (56.6 ± 18.0) and (68.4

  6. Demonstration of the right inferior phrenic artery by using multislice helical CT

    International Nuclear Information System (INIS)

    Zhao Shaohong; Liu Xin; Cai Zulong; Zhao Hong; Yang Li

    2006-01-01

    Objective: To demonstrate the origin of the right inferior phrenic artery (RIPA) in normal and hepatocellular carcinoma (HCC) patients and provide valuable anatomical information for angiographers before and after transcatheter arterial chemoembolization (TACE). Methods: Four hundred and forty consecutive patients including 133 HCC cases who had biphase abdominal CT were assessed in this study. The routine abdominal enhanced CT scan (GE, LightSpeed16) was performed with 120 kV, 200-240 mAs, 10 mm collimation, 1.375 pitch, and 10 mm reconstruction interval at 22-25 seconds for arterial phase triggered by timing bolus, 60 seconds for portal venous phase after injection of 100 ml contrast material (300 mg I/ml) at a rate of 3.5 ml/s. Multiplanar reconstruction (MPR) and maximum intensity projection (MIP) images were generated using 1.25 mm images reconstructed with 1 mm interval in arterial phase and reviewed by two radiologists. An enhanced artery medial-posterior to the IVC, originated from aorta or its branches to the diaphragmatic dome was interpreted as the RIPA. Results: The RIPA was showed in all 440 patients (100%). Among 218 (49.5%) RIPAs originated from the aorta, 140 were from the fight side of the aorta, 22 from the left side of the aorta, 56 from the anterior wall of the aorta, 36 RIPAs had the same origin with the left inferior phrenic artery. Among 138 (31.4%) RIPAs from the celiac artery, 10 RIPAs had the same origin with the left gastric artery, and 33 RIPAs had the same origin with the left inferior phrenic artery. 78 (17.7%) were from the fight renal artery, 6 (1.4%) were from the left gastric artery (the left gastric artery from aorta). The dilatation of the RIPA was demonstrated in 16 of 133 hepatocellular carcinoma patients. Conclusion: Multislice helical CT could demonstrate the origin of the RIPA in arterial phase and provide useful anatomical information for angiographer before and after TACE. (authors)

  7. Observation of normal appearance and wall thickness of esophagus on CT images

    International Nuclear Information System (INIS)

    Xia Fan; Mao Jingfang; Ding Jinquan; Yang Huanjun

    2009-01-01

    Purpose: This study sought to observe the appearance of normal esophagus, measure and record the thickness of esophageal wall in order to offer reference for estimating esophageal wall abnormalities and delineating gross tumor target of esophageal carcinomas on CT images. Materials and methods: From September 2006 to February 2007, 110 consecutive CT films from adult patients without esophageal diseases were collected and studied. On CT images the entire esophagus was divided into cervical, thoracic, retrocardiac and intraabdominal segments. The appearance of esophagus was described when the esophagus contracted or dilated. Thickness of esophageal wall and diameters of esophageal cavities were measured by hard-copy reading with a magnifying glass. Age, sex and the thickness of subcutaneous fat of each patient were recorded. Results: It was observed that the esophagus presented both contracted and dilated status on CT images. In each segment there were certain portions of esophagus in complete contraction or dilatation. 47 images (42.7%) showed contracted esophagus in each segment available for measurement. The largest wall thickness when esophagus was in contraction and dilatation was 4.70 (95%CI: 4.44-4.95) mm and 2.11 (95%CI: 2.00-2.23) mm, respectively. When contracting, the intraabdominal esophagus was thicker than the cervical, thoracic and retrocardiac parts, and the average thickness was 5.68 (95%CI: 5.28-6.09) mm, 4.67 (95%CI: 4.36-4.86) mm, 4.56 (95%CI: 4.31-4.87) mm, and 4.05 (95%CI: 3.71-4.21) mm, respectively. When the esophagus was dilating, the average esophageal wall thickness was between 1.87 and 2.70 mm. The thickest part was cervical esophagus. Thickness of esophageal wall was larger in males than that of females (5.26 mm vs. 4.34 mm p < 0.001). Age and the thickness of subcutaneous fat had no significant impact on the thickness of esophageal wall (p-value was 0.056 and 0.173, respectively). Conclusion: The Observation of normal appearance and

  8. The similar hexheimer reaction during initial treatment of pulmonary tuberculosis: CT appearances

    International Nuclear Information System (INIS)

    Lu Yan; Zhou Xinhua; Xie Ruming; Xu Jinping

    2009-01-01

    Objective: To investigate CT features of similar Hexheimer's reaction during initial treatment of active pulmonary tuberculosis. Methods: The similar Hexheimer's reaction in 44 patients diagnosed by clinic and follow-up CT scans were retrospectively reviewed by three radiologists. Results: During initial treatment of active pulmonary tuberculosis, development of radiographic progression were observed in 57 foci, including 28 pulmonary lesions increased at the site of their original lesion or new opacities elsewhere, ipsilateral or contralateral to the original lesion or both, 10 lesions related to the pleura (pleural effusion, pleural tuberculoma), 15 lymphadenectasis, 3 thymus reactions, and 1 cardiac pericardium thickening, respectively. These reactions appeared from the 20 days to 3.5 months, then with continuation of the initial chemotherapy for 1.0-3.0 months, the radiographic response was excellent with the areas of progression and the original lesions demonstrating resolution or improvement. Conclusion: The CT appearances of similar Hexheimer's reaction during initial treatment of active tuberculosis are specific to a certainty. (authors)

  9. Cost-effectiveness analysis on the results of screening of lung cancer using helical CT conducted by the anti-lung cancer association (ALCA)

    International Nuclear Information System (INIS)

    Iinuma, Takeshi; Kaneko, Masahiro; Moriyama, Noriyuki; Misawa, Jun

    1999-01-01

    To compare Yen/person saved in lung cancer screening using helical CT with Yen/person in the screening using conventional direct chest X-rays conducted under the Anti-lung cancer association program of the Tokyo Health Service Association. A mathematical model for cancer screening was used to estimate net number of person relieved from lung cancer by the screening and net cost required for the screening. Finally cost-effectiveness ratios in terms of Yen/person saved were calculated and compared between the two programs. Several important variables employed in the model were as follows: 5 year survival rate in chest X-ray group was 50%, and the rate in helical CT group was 75%. Cost of screening in the chest X-ray group was 15,000 Yen, and that in the helical CT group was 25,000 Yen. Cost/person screened was 14,470 Yen for chest X-ray and 21,890 Yen for helical CT. Cost/person saved was 267 x 10 5 Yen in X-ray group and 112 x 10 5 Yen in CT group. Thus the cost was higher, but cost-effectiveness ratio was better in the CT screening group. Helical CT can be adopted for lung cancer screening in stead of chest X-ray if total cost is affordable. (author)

  10. Application of low dose multi-slice helical CT in orbital trauma patients

    International Nuclear Information System (INIS)

    Yang Rui; Dai Limei; Li Jianying; Wang Fengyan; Du Guoquan

    2010-01-01

    Objective: To investigate the most appropriate low radiation dose in multi-slice CT (MSCT) scans for orbital trauma patients. Methods: Thirty trauma patients with suspected orbital fractures who underwent helical CT scans with a 64-MSCT using regular dose were selected. Noise was artificially introduced to the axial images using an image space noise addition tool to simulate 6 sets of lower dose scans with tube current of 30, 70, 100, 140, 170 and 200 mA, respectively. The lowest tube current with adequate image quality for confident diagnosis was determined based on the evaluation of the overall image quality and fracture detection on images at different dose levels. The determined lowest tube current was then validated using clinical scans. Radiation dose related parameters CTDIvol, DLP, ED were also recorded. Image quality was evaluated according to its low-density resolution, noise and structure clarity and characterized into 5-grades of excellent, good, fair, worse and worst. Rank sum test and χ 2 test were used for statistics. Results: In 30 trauma patients with regular dose of 300 mA, there were 30 cases of orbital fracture, 19 cases of intraorbital emphysema, 12 cases of ocular muscle injury and 1 case of intraorbital foreign body. These changes could still be clearly observed and correctly diagnosed when the tube current was reduced to as low as 70 mA. However, the overall image quality was mostly fair. At the simulated dose of 100 mA, the majority of images were characterized as excellent or good, and there was no statistical difference compared with that of regular dose scans (P>0.05). In the clinical evaluation for 20 orbital trauma patients with the reduced tube current of 100 m A , the majority of images were judged to be excellent (9 cases) or good (17 cases) and fair (4 cases). The radiation dose (0.29 mSv) was reduced by 70% compared with that of regular tube current of 300 mA (0.86 mSv). Conclusion: The tube current of MSCT may be used as low as

  11. Normal appearance and size of the diaphragmatic crura in children: CT evaluation

    International Nuclear Information System (INIS)

    Brengle, M.; Cohen, M.D.; Katz, B.

    1996-01-01

    Purpose. The objectives of the study were to document the normal CT appearance and size of the crura of the diaphragm in children. Materials and methods. The CT scans of 80 children (0-15 years) were reviewed. The children were divided into eight age groups. The maximal transverse diameters of the right and left crura were measured. They were normalized by comparison with the transverse and anterior-posterior diameters of the 12th thoracic vertebra (T12) and the transverse abdominal diameter at T12. The crura were also evaluated as to whether their contour was smooth or nodular. Results. The diaphragmatic crura of smaller children appear large, relative to body size and the diameters of the T12 vertebral body, compared with those in older children. Crural width does not increase significantly with age. Additionally, the crura were found to have a greater tendency to be nodular in appearance in children under the age of 5 years than in older children. Conclusion. Diaphragmatic crura are more nodular and larger relative to body size in younger children. (orig.). With 6 figs., 2 tabs

  12. Optimized enhancement in helical CT: Experiences with a real-time bolus tracking system in 628 patients

    International Nuclear Information System (INIS)

    Kirchner, J.; Kickuth, R.; Laufer, U.; Noack, M.; Liermann, D.

    2000-01-01

    AIMS: Ultrafast detector technology enables bolus-triggered application of contrast media. In a prospective study we investigated the benefit of this new method with the intention of optimizing enhancement during examination of the chest and abdomen. MATERIALS AND METHODS: In total, we examined 548 patients under standardized conditions. All examinations were performed on a Somatom Plus 4 Power CT system (Siemens Corp., Forchheim, Germany) using the CARE-Bolus software. This produces repetitive low-dose test images (e.g. for the lung: 140 kV, 43 mA, TI 0.5 s) and measures the Hounsfield attenuation in a pre-selected region of interest. After exceeding a defined threshold, a diagnostic spiral CT examination was begun automatically. The data obtained from 321 abdominal CT and 179 lung CT examinations were correlated with different parameters such as age, weight and height of the patients and parameters of vascular access. In a group of 80 patients, the injection of contrast medium was stopped after reaching a pre-defined threshold of an increase of 100 HU over the baseline. Then, we assessed the maximal enhancement of liver, pulmonal artery trunk and aortic arch. RESULTS: There was no correlation between bolus geometry and age, body surface or weight. In helical CT of the abdomen the threshold was reached after a mean trigger time of 27 s (range 13-67 s) and only 65 ml (range 41-105 ml) of contrast medium were administered. In helical CT of the lung the threshold was reached after 21 s (range 12-48 s) and the mean amount of administered contrast medium was 48 ml (range 38-71 ml). CONCLUSION: Bolus triggering allows optimized enhancement of the organs and reduces the dose of contrast material required compared with standard administration. Kirchner, J. (2000). Clinical Radiology 55, 368-373

  13. Optimized enhancement in helical CT: experiences with a real-time bolus tracking system in 628 patients.

    Science.gov (United States)

    Kirchner, J; Kickuth, R; Laufer, U; Noack, M; Liermann, D

    2000-05-01

    Ultrafast detector technology enables bolus-triggered application of contrast media. In a prospective study we investigated the benefit of this new method with the intention of optimizing enhancement during examination of the chest and abdomen. In total, we examined 548 patients under standardized conditions. All examinations were performed on a Somatom Plus 4 Power CT system (Siemens Corp., Forchheim, Germany) using the CARE-Bolus software. This produces repetitive low-dose test images (e.g. for the lung: 140 kV, 43 mA, TI 0.5 s) and measures the Hounsfield attenuation in a pre-selected region of interest. After exceeding a defined threshold, a diagnostic spiral CT examination was begun automatically. The data obtained from 321 abdominal CT and 179 lung CT examinations were correlated with different parameters such as age, weight and height of the patients and parameters of vascular access. In a group of 80 patients, the injection of contrast medium was stopped after reaching a pre-defined threshold of an increase of 100 HU over the baseline. Then, we assessed the maximal enhancement of liver, pulmonal artery trunk and aortic arch. There was no correlation between bolus geometry and age, body surface or weight. In helical CT of the abdomen the threshold was reached after a mean trigger time of 27 s (range 13-67 s) and only 65 ml (range 41-105 ml) of contrast medium were administered. In helical CT of the lung the threshold was reached after 21 s (range 12-48 s) and the mean amount of administered contrast medium was 48 ml (range 38-71 ml). Bolus triggering allows optimized enhancement of the organs and reduces the dose of contrast material required compared with standard administration. Copyright 2000 The Royal College of Radiologists.

  14. Evaluation of residual hepatocellular carcinoma after transcatheter arterial chemoembolization: Comparison between contrast-enhanced helical CT and contrast-enhanced power doppler ultrasonography

    International Nuclear Information System (INIS)

    Kim, Seung Hoon; Lim, Hyo Keun; Lee, Won Jae

    2001-01-01

    To evaluate the effectiveness of contrast-enhanced helical CT and contrast-enhanced power doppler ultrasonography (PDUS) in assessing the therapeutic effect of transcatheter arterial chemoembolization (TACE) in hepatocellular carcinomas (HCCs). The follow-up contrast-enhanced helical CT and contrast-enhanced PDUS were performed for twenty-nine nodular HCCs from twelve patients previously treated with TACE. We defined the residual HCCs as intratumoral enhancing area on contrast-enhanced helical CT and color signal on contrast-enhanced PDUS. The interval between two examinations was less than 2 weeks (mean, 9 days). Two radiologists evaluated two examinations by consensus, and the results of these two examination were compared with the findings of other examinations including CT, angiography, and/or pathology to calculate the sensitivity, specificity and accuracy of two examinations. Of the 29 HCCs, 20 had residual HCCs whereas no residual HCCs in 9 HCCs on pathologic examination and/or follow-up radiologic study. The sensitivity, sensitivity and accuracy of contrast-enhanced helical CT were 65 (13/20), 89 (8/9), and 72% (21/29) while those of contrast-enhanced PDUS were 100 (20/20), 89 (8/9) and 97% (28/29), respectively. A microbubble contrast-enhanced PDUS was more effective in the detection of residual tumor in HCCs following TACE than contrast-enhanced helical CT.

  15. Experimental study of quantity to be taken as patient dose in helical multi-slice CT scan

    International Nuclear Information System (INIS)

    Liu Lantao; Wei Kedao; Yue Brorong; Wang Jianchao

    2009-01-01

    Objective: To bring forward a novel quantity which is used to be taken as effective dose in helical multi - slice CT scan and to validate it by experiment. Methods: Dot chamber and pencil-chamber were used to measure the doses which were performed under axial mode and helical multi-slice mode. Then the readings of doses were compared and analyzed. Results: The dose reading from dot chamber was close to the one from pencil - chamber under axial mode. The ratio is 1.14 for the readings from dot chamber under two scan modes and is 2.88 for the readings from pencil-chamber under two scan modes. Conclusions: The dose measured from dot chamber is an effective quantity to be taken as effective dose. However it is insufficient that the CTDI and DLP be used to be taken as effective dose as the limitation of pencil-chamber in length. (authors)

  16. THORACIC COMPLICATIONS OF OESOPHAGEAL CARCINOMA- A RETROSPECTIVE ANALYSIS OF CT APPEARANCES

    Directory of Open Access Journals (Sweden)

    Piyush Joshi

    2017-07-01

    Full Text Available BACKGROUND Oesophageal cancer is a common gastrointestinal tract malignancy and Computed Tomography (CT is generally used for its initial evaluation and staging. Due to the anatomical relationships of the oesophagus, malignancies afflicting it can also give rise to various pulmonary and thoracic complications. The staging CT can also be used to detect and evaluate these complications. Detection of concurrent thoracic complications in addition to the primary malignancy is imperative to institute appropriate management. The aim of the study is to analyse and discuss the various thoracic complications in cases of oesophageal carcinoma detected on Multidetector Computed Tomography (MDCT. MATERIALS AND METHODS MDCT images of 27 cases of histopathologically-proven carcinoma oesophagus who had thoracic complications in addition to features of malignancy and metastases were retrospectively analysed. The various pulmonary and thoracic complications in addition to the primary lesions were assessed and evaluated. RESULTS There were 27 cases of oesophageal carcinoma with complications, of which there were 20 patients who had pulmonary consolidation/pneumonitis, 5 had oesophago-respiratory fistulae, 1 had a lung abscess, 2 had pericardial effusions, 3 had pleural effusions, 2 cases of airway compromise with atelectasis and 2 cases with Pulmonary Thromboembolism (PTE. CONCLUSION The routine chest CT for evaluation and staging of the primary tumour in cases of oesophageal carcinoma can also reveal thoracic complications directly or indirectly related the cancer some of which may alter management. The most common of these are pneumonia and oesophago-respiratory fistulas. Others like pulmonary thromboembolism may require immediate intervention. An awareness of the spectrum of imaging appearances of these complications and due vigilance while interpreting chest CT studies will aid decision making and institution of appropriate management.

  17. Normal thymus in adults: appearance on CT and associations with age, sex, BMI and smoking

    International Nuclear Information System (INIS)

    Araki, Tetsuro; Nishino, Mizuki; Hatabu, Hiroto; Gao, Wei; Dupuis, Josee; Hunninghake, Gary M.; Washko, George R.; Murakami, Takamichi; O'Connor, George T.

    2016-01-01

    To investigate CT appearance and size of the thymus in association with participant characteristics. 2540 supposedly healthy participants (mean age 58.9 years, 51 % female) were evaluated for the CT appearance of thymic glands with four-point scores (according to the ratio of fat and soft tissue), size and morphology. These were correlated with participants' age, sex, BMI and smoking history. Of 2540 participants, 1869 (74 %) showed complete fatty replacement of the thymus (Score 0), 463 (18 %) predominantly fatty attenuation (Score 1), 172 (7 %) half fatty and half soft-tissue attenuation (Score 2) and 36 (1 %) solid thymic gland with predominantly soft-tissue attenuation (Score 3). Female participants showed less fatty degeneration of the thymus with higher thymic scores within age 40-69 years (P < 0.001). Participants with lower thymic scores showed higher BMI (P < 0.001) and were more likely to be former smokers (P < 0.001) with higher pack-years (P = 0.04). Visual assessment with four-point thymic scores revealed a sex difference in the fatty degeneration of the thymus with age. Women show significantly higher thymic scores, suggesting less fat content of the thymus, during age 40-69 years. Cigarette smoking and high BMI are associated with advanced fatty replacement of the thymus. (orig.)

  18. Normal thymus in adults: appearance on CT and associations with age, sex, BMI and smoking

    Energy Technology Data Exchange (ETDEWEB)

    Araki, Tetsuro [Harvard Medical School, Department of Radiology, Center for Pulmonary Functional Imaging, Brigham and Women' s Hospital, Boston, MA (United States); Kinki University Faculty of Medicine, Department of Radiology, Osaka-Sayama (Japan); Nishino, Mizuki; Hatabu, Hiroto [Harvard Medical School, Department of Radiology, Center for Pulmonary Functional Imaging, Brigham and Women' s Hospital, Boston, MA (United States); Gao, Wei [Boston University School of Public Health, Department of Biostatistics, Boston, MA (United States); Dupuis, Josee [Boston University School of Public Health, Department of Biostatistics, Boston, MA (United States); The National Heart Lung and Blood Institute' s Framingham Heart Study, Framingham, MA (United States); Hunninghake, Gary M.; Washko, George R. [Harvard Medical School, The Pulmonary and Critical Care Division, Brigham and Women' s Hospital, Boston, MA (United States); Murakami, Takamichi [Kinki University Faculty of Medicine, Department of Radiology, Osaka-Sayama (Japan); O' Connor, George T. [The National Heart Lung and Blood Institute' s Framingham Heart Study, Framingham, MA (United States); Boston University School of Medicine, Pulmonary Center and Department of Medicine, Boston, MA (United States)

    2016-01-15

    To investigate CT appearance and size of the thymus in association with participant characteristics. 2540 supposedly healthy participants (mean age 58.9 years, 51 % female) were evaluated for the CT appearance of thymic glands with four-point scores (according to the ratio of fat and soft tissue), size and morphology. These were correlated with participants' age, sex, BMI and smoking history. Of 2540 participants, 1869 (74 %) showed complete fatty replacement of the thymus (Score 0), 463 (18 %) predominantly fatty attenuation (Score 1), 172 (7 %) half fatty and half soft-tissue attenuation (Score 2) and 36 (1 %) solid thymic gland with predominantly soft-tissue attenuation (Score 3). Female participants showed less fatty degeneration of the thymus with higher thymic scores within age 40-69 years (P < 0.001). Participants with lower thymic scores showed higher BMI (P < 0.001) and were more likely to be former smokers (P < 0.001) with higher pack-years (P = 0.04). Visual assessment with four-point thymic scores revealed a sex difference in the fatty degeneration of the thymus with age. Women show significantly higher thymic scores, suggesting less fat content of the thymus, during age 40-69 years. Cigarette smoking and high BMI are associated with advanced fatty replacement of the thymus. (orig.)

  19. CT and MRI appearances and radiologic staging of pediatric renal cell carcinoma

    Energy Technology Data Exchange (ETDEWEB)

    Downey, Ryan T. [University of Michigan Health System, Department of Radiology, Ann Arbor, MI (United States); Dillman, Jonathan R.; Ladino-Torres, Maria F.; Strouse, Peter J. [University of Michigan Health System, Section of Pediatric Radiology, C.S. Mott Children' s Hospital, Department of Radiology, Ann Arbor, MI (United States); McHugh, Jonathan B. [University of Michigan Health System, Department of Pathology, Ann Arbor, MI (United States); Ehrlich, Peter F. [University of Michigan Health System, Department of Surgery, Section of Pediatric Surgery, Ann Arbor, MI (United States)

    2012-04-15

    Renal cell carcinoma (RCC) is an uncommon but noteworthy primary pediatric renal malignancy. There is a paucity of published data regarding the CT/MRI appearances and accuracy of pretreatment radiologic staging of this form of cancer in children. To review the various CT/MRI appearances of pediatric RCC and assess the accuracy of pretreatment radiologic staging using these imaging modalities. Institutional Departments of Pathology and Radiology records were searched from 1995 through 2010 for children (younger than 18 years of age) with RCC. Available pretreatment contrast-enhanced abdominopelvic CT and MRI examinations were reviewed by two radiologists. Pertinent imaging findings were documented by consensus, and correlation was made between radiologic and surgicopathological TNM staging. Pretreatment imaging studies from 10 RCCs in nine children (four girls and five boys; mean age 12.9 years) were reviewed. The mean size of the primary tumor was 6.2 cm (range, 1.5-12.6 cm). Ninety percent of RCCs demonstrated heterogeneous postcontrast enhancement. Fifty percent of masses had associated hemorrhage, while 40% contained internal calcification. Regarding TNM staging, N staging was correct for 10 of 10 tumors, while M staging was correct for 10 of 10 tumors. Imaging correctly staged only 4 of 10 tumors with respect to T stage. Radiologic and surgicopathological overall staging were concordant for 8 of 10 tumors. Pediatric RCCs typically present as large, heterogeneous masses, and they commonly hemorrhage and contain internal calcification. Radiologic and surgicopathological overall TNM staging are frequently concordant, although radiologic T staging is often incorrect. (orig.)

  20. Optimization of multi-slice helical respiration-correlated CT: the effects of table speed and rotation time

    International Nuclear Information System (INIS)

    Wink, Nicole M; McNitt-Gray, Michael F; Solberg, Timothy D

    2005-01-01

    While respiration-correlated CT is gaining acceptance in clinical radiotherapy, the effect of scanning parameters on the image quality has yet to be addressed. The intent of this study was to characterize the effects of gantry rotation and table speed on various image quality characteristics in multi-slice, helical, retrospectively-gated CT images. Images of stationary and moving phantoms were obtained in helical mode on a 20-slice CT scanner. Motion was generated by a computer-controlled platform capable of moving simultaneously in two dimensions. Motion was monitored using a pressure gauge inserted inside an adjustable belt. Selected scans were retrospectively gated into ten phases based on the monitored motion. Gantry rotation speeds of 0.5 s and 1.0 s were evaluated with pitches ranging from 0.1 to 0.45. Several parameters, including calculated object volumes, trajectory (movement from peak to trough), deformation (actual volume divided by volume created with the maximum diameter of contoured object) and z-axis resolution, were used to characterize image quality. These studies indicate that for objects in the peak phase of a movement pattern that simulates breathing, retrospectively gated scans using fast gantry rotation speeds produce volume, trajectory, deformation and z-axis resolution results comparable with those of a stationary object

  1. The quality of reconstructed 3D images in multidetector-row helical CT: experimental study involving scan parameters

    International Nuclear Information System (INIS)

    Shin, Ji Hoon; Lee, Ho Kyu; Choi, Choong Gon; Suh, Dae Chul; Lim, Tae Hwan; Kang, Weechang

    2002-01-01

    To determine which multidetector-row helical CT scanning technique provides the best-quality reconstructed 3D images, and to assess differences in image quality according to the levels of the scanning parameters used. Four objects with different surfaces and contours were scanned using multidetector-row helical CT at three detector-row collimations (1.25, 2.50, 5.00 mm), two pitches (3.0, 6.0), and three different degrees of overlap between the reconstructed slices (0%, 25%, 50%). Reconstructed 3D images of the resulting 72 sets of data were produced using volumetric rendering. The 72 images were graded on a scale from 1 (worst) to 5 (best) for each of four rating criteria, giving a mean score for each criterion and an overall mean score. Statistical analysis was used to assess differences in image quality according to scanning parameter levels. The mean score for each rating criterion, and the overall mean score, varied significantly according to the scanning parameter levels used. With regard to detector-row collimation and pitch, all levels of scanning parameters gave rise to significant differences, while in the degree of overlap of reconstructed slices, there were significant differences between overlap of 0% and of 50% in all levels of scanning parameters, and between overlap of 25% and of 50% in overall accuracy and overall mean score. Among the 18 scanning sequences, the highest score (4.94) was achieved with 1.25 mm detector-row collimation, 3.0 pitch, and 50% overlap between reconstructed slices. Comparison of the quality of reconstructed 3D images obtained using multidetector-row helical CT and various scanning techniques indicated that the 1.25 mm, 3.0, 50% scanning sequence was best. Quality improved as detector-row collimation decreased; as pitch was reduced from 6.0 to 3.0; and as overlap between reconstructed slices increased

  2. Unusual presentation of a pancreatic insulinoma in helical CT and dynamic contrast-enhanced MR imaging: case report

    Energy Technology Data Exchange (ETDEWEB)

    Iglesias, A.; Arias, M.; Brasa, J. [Unidad de Resonancia Magnetica (Medtec), Hospital Xeral-Cies, Vigo (Spain); Casal, M. [Unidad de Radiologia Intervencionista, Hospital Xeral-Cies, Vigo (Spain); Paramo, C. [Servicio de Endocrinologia, Hospital Xeral-Cies, Vigo (Spain); Fiano, C. [Servicio de Anatomia Patologica, Hospital Xeral-Cies, Vigo (Spain)

    2001-06-01

    Insulinomas are pancreatic neoplasms that can be radiologically characterized typically because of their tendency to present intense and early contrast enhancement with a wash-out phenomenon. In this sense, we report an unusual case of a hypovascular solid pancreatic insulinoma confirmed with surgery and pathologic analysis, in a patient with normal serum insulin levels. In the two-phase helical CT, the mass behaved as a hypodense lesion with respect to the surrounding pancreatic parenchyma during the arterial phase and as a hypointense lesion during the dynamic contrast-enhanced MR imaging. Pathologic examination demonstrated a hypercellular tumor with poor vascularization of intervening stroma which showed prominent amyloid deposits. (orig.)

  3. Unusual presentation of a pancreatic insulinoma in helical CT and dynamic contrast-enhanced MR imaging: case report

    International Nuclear Information System (INIS)

    Iglesias, A.; Arias, M.; Brasa, J.; Casal, M.; Paramo, C.; Fiano, C.

    2001-01-01

    Insulinomas are pancreatic neoplasms that can be radiologically characterized typically because of their tendency to present intense and early contrast enhancement with a wash-out phenomenon. In this sense, we report an unusual case of a hypovascular solid pancreatic insulinoma confirmed with surgery and pathologic analysis, in a patient with normal serum insulin levels. In the two-phase helical CT, the mass behaved as a hypodense lesion with respect to the surrounding pancreatic parenchyma during the arterial phase and as a hypointense lesion during the dynamic contrast-enhanced MR imaging. Pathologic examination demonstrated a hypercellular tumor with poor vascularization of intervening stroma which showed prominent amyloid deposits. (orig.)

  4. Clinical application of multi-slice helical CT volumetric scanning in lumber spine

    International Nuclear Information System (INIS)

    Wang Ling; Ge Yinghui; Zhu Shaocheng; Zhang Ming; Cheng Tianming; Lei Zhidan; Lv Chuanjian; Sun Xiaoping; Wu Minghui; Guo Ying; Ma Qianli; Wen Zeying

    2008-01-01

    Objective: To evaluate the clinical application value of multi-slice helical CT volumetric (VH) scanning in lumber spine. Methods: One thousand of patients with back and leg pain who underwent CT examinations were selected as subjects. We simulated the traditional protocol of single-slice(SS) discrete scanning for L3/4, L4/5, and L5/S1 intervertebral discs. The VH scanning mode was performed with 120 kV, 210 mAs, pitch of 1.5 and coverage of 97.5 mm. The simulated SS scanning mode was performed with 120 kV, 240 mAs and coverage of 45.0 mm. The diagnostic outcomes and the radiation doses were compared between the two scanning modes. Two groups doctors observed ten terms, including the osseous spinal stenosis, narrowed intervertebral space and so on in two scanning modes respectively. Then consistency analysis of the data was carded out. Results: The VH scanning mode showed far more features than the SS mode. The detection rates of the VH mode in the osseous spinal stenosis, narrowed intervertebral space, herniated nucleus pulposus, narrowed lateral recess, vertebral lesion, hypertrophy of L5 transverse process, abnormal direction of facet, facet degeneration, lumbar spondyloschisis, and paraspinal soft tissue were 11.8% (n=118), 38.5% (n=385), 9.3% (n=93), 46.8% (n=468), 31.4% (n=314), 5.7% (n= 57), 25.4% (n=254), 49.7% (n=497), 9.9% (n=99), and 0.6% (n=6) respectively, while the detection rates of the SS mode in ten terms were 5.6% (n=56), 0, 0.6% (n=6), 27.9% (n=279), 22.4% (n=224), 1.2% (n=12), 16.7% (n=167), 37.2% (n=372), 0.5% (n=5), and 0.2% (n=2) respectively. The difference between the two groups had statistically significance (average P 0.05). The detection rates of the VH mode were higher than the SS mode in the osseous spinal stenosis, narrowed intervertebral space, herniated nucleus pulposus, lumbar spondyloschisis, being 6.2% (n=62), 38.5% (n=385), 8.7% (n=87), and 9.4% (n=94), respectively. In addition, VH mode only partially showed the articular

  5. The CT appearance of ``reversible`` cerebral pseudoatrophy in anorexia nervosa; Obraz KT ``odwracalnego`` rzekomego zaniku mozgu w jadlowstrecie nerwowym

    Energy Technology Data Exchange (ETDEWEB)

    Boron, Z.; Kozlowska, R.; Grzegorzewski, M.; Nawrot, M.; Bulawska, I. [Katedra i Zaklad Radiologii i Diagnostyki Narzadowej, Akademia Medyczna, Bydgoszcz (Poland)

    1995-12-31

    The CT appearance of ``reversible`` cerebral pseudoatrophy resulting from anorexia nervosa was demonstrated. The CT studies were performed in 3 young women with typical clinical course of anorexia nervosa. In all of them computed tomography revealed dilatation of the subarachnoid fluid space. After 5 months of therapy the follow-up scans have reverted to normal in all cases. (author) 5 refs, 2 figs

  6. CT appearance of hilar and mediastinal enlarged lymph nodes of coal worker's pneumoconiosis

    International Nuclear Information System (INIS)

    Ma Daqing; Guan Yansheng; Tang Hongqu; He Wen; Chen Budong; Zhang Yansong; Li Jun

    2000-01-01

    Objective: To study the CT appearance of the hilar and mediastinal enlarged lymph nodes in coal worker's pneumoconiosis (CWP), its pathological basis and diagnostic value for CWR complicated with lung cancer. Methods: (1) Twelve isolated lungs with CWP obtained at autopsy were inflated and fixed. CT scan was performed. The pathologic findings of enlarged lymph nodes were identified. (2) CT findings of hilar and mediastinal enlarged lymph nodes of 71 cases with CWP and 22 cases of CWP complicated with lung cancer were analyzed. Results: (1) Most of the enlarged hilar and mediastinal lymph nodes in simple CWR was in third stage of fibrosis. The fourth stage of fibrosis was only seen in lymph nodes of a case with complicated CWP. In this case the necrotic materials of lymph nodes eroded adjacent bronchi and vessels, and coalesced with progressive massive fibrosis (PMF). (2) The average number of lymph nodes in cases of complicated CWP was more than that of simple CWP (P 2 cm was 7.4%. (3) The prevalence of lymph nodes calcification in CWP was 61.1%, but egg shell calcification was only 14.7%. (4) In the cases of CWP complicated with lung cancer, lymph node > 2 cm was 20.8%, that was more than CWP (P 3 cm was 7.6%. Conclusion: Lymph nodes up to 1 cm may have dust fibrosis and coal silicosis nodules. The lymph nodes >2 cm is more common in CWP complicated with lung cancer than in simple CWP. The lymph nodes > 3 cm indicates higher probability of CWP with lung cancer than PMF

  7. A clinical study concerning hepatic arterial dominant phase and arrival time of contrast media on helical dynamic CT

    International Nuclear Information System (INIS)

    Matsubara, Susumu; Uchida, Chiharu; Sato, Sei; Ishida, Junichi; Masuya, Ryozo; Makiguchi, Mako; Kanamori, Isao

    2001-01-01

    Hepatic arterial dominant phase in helical dynamic CT was optimized by measuring the arrival time of contrast media (ATCM) with time-density curve (TDC). Subjects were 1005 patients (577 males and 428 females) and 98 nodules diagnosed as advanced hepatocellular carcinoma (HCC). The CT was done with Toshiba 4MHU X-vision SP, ultrasonography with Toshiba SSH-160A and automatic infusion of the contrast medium, iopamidol or iohexol, with Nemotokyorindo Autoenhance A-50. ATCM was found correlated with pulse rate and with arterial diameter, and significantly different between the sex. Elevation slope of TDC was suggested to be made constant by a defined infusion time of the dose corrected by body weight. Fluctuation of TDC among patients , when normalized by ATCM, was found smaller and the TDC was suggested to be useful for better imaging of HCC of less than 10 mm diameter. (K.H.)

  8. The prevalence of erosive osseous changes of the articular eminence in the temporomandibular joint in patients with mandibular prognathism without internal derangement. MR and helical CT findings

    Energy Technology Data Exchange (ETDEWEB)

    Hayashi, Takafumi; Ito, Jusuke; Tanaka, Rei; Koyama, Jun-ichi; Kobayashi, Fukiko [Niigata Univ. (Japan). Graduate School of Medical and Dental Sciences

    2002-06-01

    The aim of this study was to assess the prevalence of erosive osseous changes of the articular eminence in the temporomandibular joint without internal derangement. Sixty joints of 30 consecutive patients with mandibular prognathism were evaluated with both MR imaging and helical CT. On MPR images obtained with helical CT, erosive osseous changes of the articular eminence were observed in 18 joints (30%) of 13 patients. None of the joints studied demonstrated an osseous change in the mandibular condyle. MR imaging failed to detect erosive osseous changes of the articular eminence in all of the joints studied. In conclusion, MPR images obtained with helical CT were of value to detect erosive osseous changes of the articular eminence. (author)

  9. The prevalence of erosive osseous changes of the articular eminence in the temporomandibular joint in patients with mandibular prognathism without internal derangement. MR and helical CT findings

    International Nuclear Information System (INIS)

    Hayashi, Takafumi; Ito, Jusuke; Tanaka, Rei; Koyama, Jun-ichi; Kobayashi, Fukiko

    2002-01-01

    The aim of this study was to assess the prevalence of erosive osseous changes of the articular eminence in the temporomandibular joint without internal derangement. Sixty joints of 30 consecutive patients with mandibular prognathism were evaluated with both MR imaging and helical CT. On MPR images obtained with helical CT, erosive osseous changes of the articular eminence were observed in 18 joints (30%) of 13 patients. None of the joints studied demonstrated an osseous change in the mandibular condyle. MR imaging failed to detect erosive osseous changes of the articular eminence in all of the joints studied. In conclusion, MPR images obtained with helical CT were of value to detect erosive osseous changes of the articular eminence. (author)

  10. Preliminary evaluation of helical CT colonography in detection of colonic diseases compared with double contrast barium enema

    International Nuclear Information System (INIS)

    Zhai Xiaoli; Zhang Lei; Zhai Renyou; Li Jie; Wang Yajie; Ding Yi

    2000-01-01

    Objective: To evaluate helical CT colonography in regard to technology principles, limitations, and clinical applications. Methods: Fifty-six patients underwent volume scanning using helical CT. The diseases included adenocarcinoma 39, adenomatous polyp 3, multiple diverticular 7, mucocele of appendix 1, and normal colon 6. All cases had been compared with double contrast barium enema (DCBE), proved by histology except the 6 normal colon and the 7 multiple diverticular. All CTC images were reconstructed using shaded surface display (SSD) on workstation. Then, perspective images such as the ones from DCBE were generated via ray sum. The images could clearly demonstrate the extent and detail of the disorder by using 'CUT' software, 'revolve' function, and zoom. Results: CTC correctly demonstrated 3-5 mm diverticulum, 3 mm ulcer, and 6 mm polyps. Not only show colon straitness clearly, CTC is also very sensitive to demonstrate the stenotic end of masses. In these cases, discovery rate of CTC is 100.0%, the rate of DCBE is 88.6%; CTC is more sensitive than DCBE in cases of tumor nodules. Ray sum can show the boundary of colonic mass extending to both proximal and distal ends, its discovery rate is 62.6%. Accuracy of localization for CTC is 100.0%. Conclusion: CTC is a novel technique for detecting colonic diseases. It is a safe, accurate, and non-invasive means for detection of lesions and is an efficient complement for DCBE. Further development in CTC technique is expected in the future

  11. Early clinical phase of patient's management after polytrauma using 1- and 4-slice helical CT; Fruehes klinisches Management nach Polytrauma mit 1- und 4-Schicht-Spiral-CT

    Energy Technology Data Exchange (ETDEWEB)

    Kloeppel, R.; Kahn, T. [Klinik und Poliklinik fuer Diagnostische Radiologie, Universitaetsklinikum Leipzig (Germany); Schreiter, D. [Chirurgische Intensivtherapieabteilung, Zentrum fuer Chirurgie, Universitaetsklinikum Leipzig (Germany); Dietrich, J. [Abt. Neuroradiologie der Klinik und Poliklinik fuer Diagnostische Radiologie, Universitaetsklinikum Leipzig (Germany); Josten, C. [Klinik und Poliklinik fuer Unfall- und Wiederherstellungschirurgie, Zentrum fuer Chirurgie, Universitaetsklinikum Leipzig (Germany)

    2002-07-01

    In the early clinical phase the comprehensive imaging of patients with multiple trauma using helical CT is already established. Aim of this study was to assess whether MSCT may improve the patient management and the diagnostic results.The procedure is designed as follows: after life-thretening treatment x-ray of chest and ultrasound are carried out in the emergency room. Then the patient is moved to CT. From 1998 to december 2000 241 patients were examined using a single slice helical CT (Somatom plus 4), in 2001 79 patients using a 4-slice helical CT (Somatom VZ, Siemens Med.Sol.). After CT selected radiograms of the extremities were taken.359 of 360 procedures were carried out successfully. Excluding 1 case (death during 1-sl. h CT) all relevant lesions of head, neck, and body were diagnosed. Although the patients had an injury severity score of {approx}30. The change from 1slice-helical CT to 4 slice-helical CT allowed us to reduce the stay in the CT room from 28 to 16 min. The total lethality decreased by {approx}4%.Advantages for the patient arose from the standardized examination protocol using multislice CT. If integrated in an interdisciplinary management concept, it is a good compromise between examination time, comprehensive diagnostic imaging, life-saving therapeutic procedures, and therapy planning. (orig.) [German] Die klinische Erstversorgung Polytraumatisierter schliesst inzwischen in vielen Unfallkliniken den fruehzeitigen Einsatz der Spiral-CT ein. Kann die neuerlich eingefuehrte Mehrschicht-Spiral-CT Ergebnisse und Patientenmanagement weiter verbessern?Nach lebensrettenden Sofortmassnahmen, Thoraxroentgen und Notsonographie im Schockraum erfolgte die CT: Von 1998-2000 wurden 241 Patienten mit einem 1-Schicht-Spiral-CT (Somatom plus 4) und in 2001 79 Patienten mit einem 4-Schicht-Spiral-CT (Somatom VZ, beide Siemens Med. Sol.) untersucht. Klinisch ausgewaehlte Extremitaetenaufnahmen wurden ergaenzt.359 von 360 Untersuchungen verliefen erfolgreich

  12. A three-dimensional-weighted cone beam filtered backprojection (CB-FBP) algorithm for image reconstruction in volumetric CT-helical scanning

    International Nuclear Information System (INIS)

    Tang Xiangyang; Hsieh Jiang; Nilsen, Roy A; Dutta, Sandeep; Samsonov, Dmitry; Hagiwara, Akira

    2006-01-01

    Based on the structure of the original helical FDK algorithm, a three-dimensional (3D)-weighted cone beam filtered backprojection (CB-FBP) algorithm is proposed for image reconstruction in volumetric CT under helical source trajectory. In addition to its dependence on view and fan angles, the 3D weighting utilizes the cone angle dependency of a ray to improve reconstruction accuracy. The 3D weighting is ray-dependent and the underlying mechanism is to give a favourable weight to the ray with the smaller cone angle out of a pair of conjugate rays but an unfavourable weight to the ray with the larger cone angle out of the conjugate ray pair. The proposed 3D-weighted helical CB-FBP reconstruction algorithm is implemented in the cone-parallel geometry that can improve noise uniformity and image generation speed significantly. Under the cone-parallel geometry, the filtering is naturally carried out along the tangential direction of the helical source trajectory. By exploring the 3D weighting's dependence on cone angle, the proposed helical 3D-weighted CB-FBP reconstruction algorithm can provide significantly improved reconstruction accuracy at moderate cone angle and high helical pitches. The 3D-weighted CB-FBP algorithm is experimentally evaluated by computer-simulated phantoms and phantoms scanned by a diagnostic volumetric CT system with a detector dimension of 64 x 0.625 mm over various helical pitches. The computer simulation study shows that the 3D weighting enables the proposed algorithm to reach reconstruction accuracy comparable to that of exact CB reconstruction algorithms, such as the Katsevich algorithm, under a moderate cone angle (4 deg.) and various helical pitches. Meanwhile, the experimental evaluation using the phantoms scanned by a volumetric CT system shows that the spatial resolution along the z-direction and noise characteristics of the proposed 3D-weighted helical CB-FBP reconstruction algorithm are maintained very well in comparison to the FDK

  13. The value of multislice helical CT in the diagnosis of the rib micro-fracture

    International Nuclear Information System (INIS)

    Wang Shuli; Wang Linsen; Sun Dingyuan; Deng Xin; Geng Xin; Li Jian; Liu Zhigang; Guo Lin; Jia Zhihong

    2005-01-01

    Objective: To evaluate the clinical value of MSCT with thin-section reconstruction and curved multiplanar reformation of rib micro-fracture. Methods: Thirty-eight patients suspected ribs fracture by clinical examination, which had negative appearance in X-ray film, were performed with MSCT scan with thin-section reconstructed and curved multiplanar reformation. The imaging of 5 mm, 1 mm thickness and curved reformatted imags were analysed by three groups of radiologists respectively. Results: Of the 38 patients, 26 patients were demonstrated ribs fracture with 1 mm thin-section reconstructed and curved multiplanar reformatted CT imaging, which were classified as complete fracture in 18 ribs and incomplete fracture in 41 ribs. The ends of the fractures displacement located within a distance of double-thickness of the cortex of the complete ribs fracture. With 5 mm thickness imaging, the accuracy of the diagnosis was 86.4%, 89.8% and 94.9% by three groups radiologists, respectively. Conclusion: The rib fracture is very common in clinic, the incomplete and non evident displacement complete ribs fracture are difficult to be diagnosed by plain radiography. The MSCT can produce a large range volume information scan. Thin-section reconstructed and curved multiplanar reformatted imaging should be the effective method in diagnosis of ribs fracture. The total rib pattern and location, extend of all the ribs fracture in this cases can be displayed in one scan by the curved multiplanar reformatted imaging. (authors)

  14. Multiple renal aspergillus abscesses in an AIDS patient: contrast-enhanced helical CT and MRI findings

    International Nuclear Information System (INIS)

    Heussel, C.P.; Kauczor, H.U.; Thelen, M.; Heussel, G.; Jahn, B.

    1999-01-01

    Renal insufficiency or allergic reactions for X-ray contrast agents are frequent limitations in immunocompromised hosts such as neutropenic or AIDS patients. Due to a better tolerance of contrast agents in MRI, this technique is well suited for investigation of parenchymal organs. We demonstrate an allergic AIDS patient who presented with fever and flank pain. At sonography, anechoic renal lesions were supposed to be non-complicated cysts; however, on T2-weighted MRI, the center was of high signal. Dynamic contrast-enhanced MRI of the kidneys demonstrated an enhancing rim with ill-defined margins. The lesions were supposed to be multiple bilateral abscesses. Due to the multiple dynamic contrast series, a delayed enhancement of renal parenchyma was detectable adjacent to the lesion. This was suggested as accompanying local pyelonephritis and an infectious etiology became more reliable. Aspergillus fumigatus was identified by CT-guided biopsy as the underlying microorganism. The MR appearance of this manifestation has not been described previously. (orig.)

  15. Scanning technology with multi-slice helical CT in security inspection domain

    International Nuclear Information System (INIS)

    Wang Jue; Wang Fuquan; Jiang Zenghui

    2008-01-01

    The paper analyzes the technology conditions of security inspection in home and abroad, and expatiates technology of spiral CT and how to define CT value etc, with studying on the key technology of spiral CT scanning way (X-RAY, detector, technology of pulley etc) and mutual relation. By comparing the present products of security inspection, the conclusion was drawn that it is inevitable to develop the tendency of security inspection area with the checking and discerning the substance by using the technology of multi-layer spiral CT. (authors)

  16. A BPF-FBP tandem algorithm for image reconstruction in reverse helical cone-beam CT

    International Nuclear Information System (INIS)

    Cho, Seungryong; Xia, Dan; Pellizzari, Charles A.; Pan Xiaochuan

    2010-01-01

    Purpose: Reverse helical cone-beam computed tomography (CBCT) is a scanning configuration for potential applications in image-guided radiation therapy in which an accurate anatomic image of the patient is needed for image-guidance procedures. The authors previously developed an algorithm for image reconstruction from nontruncated data of an object that is completely within the reverse helix. The purpose of this work is to develop an image reconstruction approach for reverse helical CBCT of a long object that extends out of the reverse helix and therefore constitutes data truncation. Methods: The proposed approach comprises of two reconstruction steps. In the first step, a chord-based backprojection-filtration (BPF) algorithm reconstructs a volumetric image of an object from the original cone-beam data. Because there exists a chordless region in the middle of the reverse helix, the image obtained in the first step contains an unreconstructed central-gap region. In the second step, the gap region is reconstructed by use of a Pack-Noo-formula-based filteredbackprojection (FBP) algorithm from the modified cone-beam data obtained by subtracting from the original cone-beam data the reprojection of the image reconstructed in the first step. Results: The authors have performed numerical studies to validate the proposed approach in image reconstruction from reverse helical cone-beam data. The results confirm that the proposed approach can reconstruct accurate images of a long object without suffering from data-truncation artifacts or cone-angle artifacts. Conclusions: They developed and validated a BPF-FBP tandem algorithm to reconstruct images of a long object from reverse helical cone-beam data. The chord-based BPF algorithm was utilized for converting the long-object problem into a short-object problem. The proposed approach is applicable to other scanning configurations such as reduced circular sinusoidal trajectories.

  17. Appendicitis and alternate diagnoses in children: findings on unenhanced limited helical CT

    International Nuclear Information System (INIS)

    Lowe, L.H.; Perez, R. Jr.; Scheker, L.E.; Stein, S.M.; Heller, R.M.; Hernanz-Schulman, M.

    2001-01-01

    The objective of this manuscript is to review and illustrate the findings of appendicitis, and of alternate diagnoses that may clinically or radiographically simulate appendicitis, on unenhanced limited CT in children. Potential pitfalls in unenhanced limited CT interpretation of pediatric patients will also be discussed. (orig.)

  18. Volume doubling time and growth rate of renal cell carcinoma determined by helical CT: a single-institution experience

    International Nuclear Information System (INIS)

    Lee, Ji Young; Kim, Chan Kyo; Choi, Dongil; Park, Byung Kwan

    2008-01-01

    The purpose of this study was to retrospectively evaluate the volume doubling time (VDT) and growth rate of renal cell carcinomas (RCC) on a serial computed tomography (CT) scan. Thirty pathologically proven RCCs were reviewed with helical CT. Each tumor underwent at least two CT scans. Tumor volume was determined using an area measuring tool and the summation-of-areas technique. Growth rate was evaluated in terms of diameter and volume changes. VDT and volume growth rate were compared in relation to several factors (initial diameter, initial volume, diameter growth rate, volume growth rate, tumor grade, tumor subtype, sex or age). Mean VDT of RCCs was 505 days. Mean diameter and volume growth rate were 0.59 cm/year and 19.1 cm 3 /year, respectively. For volume and diameter growth rate, tumors ≤4 cm showed lower rates than those >4 cm (P 0.05). Volume growth rate was moderately to strongly positively correlated with initial diameter, initial volume and diameter growth rate (P < 0.05). In conclusion, small RCCs grew at a slow rate both diametrically and volumetrically. More accurate assessment of tumor growth rate and VDT may be helpful to understand the natural history of RCC. (orig.)

  19. Low-dose helical computed tomography (CT) in the perioperative workup of adolescent idiopathic scoliosis

    Energy Technology Data Exchange (ETDEWEB)

    Abul-Kasim, Kasim; Overgaard, Angelica; Maly, Pavel [Malmoe University Hospital, Department of Radiology, Section of Neuroradiology, University of Lund, Malmoe (Sweden); Ohlin, Acke [Malmoe University Hospital, Department of Orthopaedic Surgery, University of Lund, Malmoe (Sweden); Gunnarsson, Mikael [Malmoe University Hospital, Department of Radiation Physics, University of Lund, Malmoe (Sweden); Sundgren, Pia C. [University of Michigan Health Systems, Department of Radiology, Division of Neuroradiology, Ann Arbor (United States)

    2009-03-15

    The study aims were to estimate the radiation dose in patients examined with low dose spine CT and to compare it with that received by patients undergoing standard CT for trauma of the same region, as well as to evaluate the impact of dose reduction on image quality. Radiation doses in 113 consecutive low dose spine CTs were compared with those in 127 CTs for trauma. The inter- and intraobserver agreement in measurements of pedicular width, and vertebral rotation, measurements of signal-to-noise ratio and assessment of hardware status were the indicators in the evaluation of image quality. The effective dose of the low dose spine CT (0.37 mSv) was 20 times lower than that of a standard CT for trauma (13.09 mSv). This dose reduction conveyed no impact on image quality. This low dose spine CT protocol allows detailed evaluation that is necessary for preoperative planning and postoperative evaluation. (orig.)

  20. Budd-Chiari syndrome: dynamic enhancement findings with multi-slice helical CT and CT angiography analysis

    International Nuclear Information System (INIS)

    Meng Xiaochun; Shan Hong; Zhu Kangshun; Xu Chuan; Zhang Jiansheng; Liu Lingyun; Ye Binbin

    2005-01-01

    Objective: To investigate the dynamic enhancement regulations of liver and their mechanism in Budd-Chiari syndrome (BCS) by using multi-slice CT and evaluate the value of CT angiography in the diagnosis of BCS. Methods: 28 cases with BCS confirmed by digital subtraction angiography (DSA) were retrospectively analyzed. All patients underwent dynamic enhancement examinations with multi-slice CT within 1 week before DSA. The relevant vessels were reconstructed respectively with MIP, VR and MPR. Compared with the results of DSA, we analyzed the dynamic enhancement regulations of liver in BCS, estimated the value of dynamic enhancement CT exams and CTA techniques in judging the obstruction level and showing collateral vessels. Results: Of all 28 cases, CT correctly showed the obstruction level in 26 cases, and 2 had incorrect results which proved to be membranous obstruction of the inferior vena cava superior to diaphragm. In 22 cases with hepatic vein obstructions, hepatic parenchyma displayed typical patchy enhancement in 19, atypical patchy enhancement in 3.8 cases among these showed benign nodules. Simultaneously, CT showed stenosis and rigidity of portal vein branches in 20, enlargement of hepatic artery in 14, hepatic collateral vessels in 20 out of 22 cases. In 6 cases with simple obstruction of inferior vena cava, hepatic changes were not found. Collateral circulations in or out of liver corresponded to the obstruction level. Conclusion: Dynamic enhancement examinations with multi-slice CT can correctly reflect the hepatic hemodynamic changes. Transverse images, combined with CTA, can explicitly display the obstruction level of vascular lesions and collateral circulations in BCS. (authors)

  1. Ligation of the internal maxillary artery for intractable epistaxis. 3D imaging of internal maxillary artery using helical CT scan

    International Nuclear Information System (INIS)

    Handa, Toru; Yazin, Koji; Hirakawa, Katsuhiro; Fukushima, Noriyuki; Takumida, Masaya; Hirata, Shitau; Iguchi, Tetsuhiko; Amano, Yoshiharu

    2001-01-01

    Sever posterior epistaxis is one of the serious clinical problems. Nasal bleeding usually occurs in the anterior septal region, where it can be seen easily and controlled with topical cautery or localized packing. When the bleeding occurs in the posterior nose, it becomes a more serious problem. Many methods have been used to control posterior epistaxis. Some of these are electrocautery, posterior nasal packing, vascular ligation and therapeutic percutaneous embolization. Between 1997 and 2000, nineteen patients were admitted to our hospital because of intractable epistaxis. There were 16 male and 3 female patients whose average age was 55 years. Ten of 19 patients were hypertensive, and none of these had undergoing treatment. Five of 19 patients received maxillary artery ligation. Clinical applications of 3D imaging of the internal maxillary artery using helical CT scan were done for 5 patients. These images were helpful for planning of ligation of the internal maxillary artery. (author)

  2. Ligation of the internal maxillary artery for intractable epistaxis. 3D imaging of internal maxillary artery using helical CT scan

    Energy Technology Data Exchange (ETDEWEB)

    Handa, Toru [Akitsu Prefectual Hospital, Hiroshima (Japan); Yazin, Koji; Hirakawa, Katsuhiro; Fukushima, Noriyuki; Takumida, Masaya; Hirata, Shitau; Iguchi, Tetsuhiko; Amano, Yoshiharu

    2001-03-01

    Sever posterior epistaxis is one of the serious clinical problems. Nasal bleeding usually occurs in the anterior septal region, where it can be seen easily and controlled with topical cautery or localized packing. When the bleeding occurs in the posterior nose, it becomes a more serious problem. Many methods have been used to control posterior epistaxis. Some of these are electrocautery, posterior nasal packing, vascular ligation and therapeutic percutaneous embolization. Between 1997 and 2000, nineteen patients were admitted to our hospital because of intractable epistaxis. There were 16 male and 3 female patients whose average age was 55 years. Ten of 19 patients were hypertensive, and none of these had undergoing treatment. Five of 19 patients received maxillary artery ligation. Clinical applications of 3D imaging of the internal maxillary artery using helical CT scan were done for 5 patients. These images were helpful for planning of ligation of the internal maxillary artery. (author)

  3. Aortic non communicating dissections. A study with helical CT; Studio dell'ematoma intramurale aortico. Aspetti con Tomografia Computerizzata spirale

    Energy Technology Data Exchange (ETDEWEB)

    Midiri, M.; Strada, A.; Stabile Ianora, A.A.; Rotondo, A.; Angelelli, G. [Bari Univ., Bari (Italy). Dipt. di Medicina Interna e Medicina Pubblica, Sez. di Diagnostica per Immagini; Scialpi, M. [Ospedale SS. Annunziata, Taranto (Italy); D' Agostino, D.; De Luca Tupputi Schinosa, L. [Bari Univ., Bari (Italy). Dipt. Emergenze Trapianto d' Organo, Sez. di Cardiochirurgia

    2000-09-01

    The evaluate the signs of aortic intramural hematoma with helical CT and the diagnostic role of this technique in patients with this condition. It was reviewed the CT findings of 396 patients submitted to emergency examinations for suspected aortic dissection from 1995 to 1999. Only 18 patients (6 women and 12 men) had CT signs of aortic intramural hematoma. Helical CT studies were carried out with the following parameters: slice thickness 10 mm, reconstruction index 10, feed 1.5 mm, conventional algorithm with minimum values of 130 kV and 125mA. All patients were examined with dynamic contrast-enhanced CT, before and after a power injection of 130 mL ionic contrast material. It was studied: hematoma localization and longitudinal extension; thickness and density of aortic wall; presence and location of intimal calcifications; integrity of intimal wall; hemo mediastinum and/or hemo thorax. Aortic wall thickening appeared as a high density crescent-shaped area at baseline CT and had low density on enhanced images in all patients. Thickening was eccentric in 14/18 patients and concentric in 4/18 only; it always exceeded 4 mm. It was found some intimal calcifications in 8 patients and hemo thorax and/or hemo mediastinum in 9 patients. A patient with type A hematoma died of cardiac tamponade a few hours after CT diagnosis. Six patients (5 type B and 1 type A) underwent anti-hypertensive treatment and radiological follow-up. Eleven patients (6 type A and 5 type B) underwent prosthesis replacement and 5 of them (3 type A and 2 type B) died of postoperative complications. In the 5 type B patients surgery was performed because of treatment-resistant pain and of the onset of ischemic complications to abdominal organs caused by involvement of the main collateral branches of the aorta. One patient with type A hematoma was submitted to drug treatment because it was judged unresectable. Intramural hematoma of the aorta is a distinct pathological entity, which should not be

  4. Multiphasic helical CT of hepatocellular carcinoma. Evaluation after chemoembolization; Tomografia Computerizzata spirale multifasica dell'epatocarcinoma. Valutazione dopo chemioembolizzazione

    Energy Technology Data Exchange (ETDEWEB)

    Catalano, O.; Esposito, M.; Sandomenico, F.; Siani, A. [Ospedale S. Maria delle Grazie, Pozzuoli, NA (Italy). Servizio di Radiologia; Nunziata, A. [Ospedale S. Maria delle Grazie, Naples (Italy). Area di Diagnostica per Immagini

    2000-06-01

    The main purpose of this work is to report the personal experience with addition of contrast-enhanced multiphase helical CT to unenhanced CT (Lipiodol CT) in the evaluation of patients with hepatocellular carcinoma treated with chemoembolization and to analyze the present role of oily agent CT. It has been retrospectively reviewed the examinations of 42 consecutive patients submitted to global chemoembolization over a 2-year period. CT was performed 18-30 days after the treatment. The Lipiodol CT study was carried out with volume acquisitions. It has been considered as nodules all well-defined areas with dense oily agent uptake; uptake itself was classified as: 0=absent, I=lower than 10% of the tumor volume; II=lower than 50%, III=50%, IV=homogeneous. Contrast-enhanced helical CT was performed with the 2-phase technique in 28 patients and with the 3-phase technique in 14; it has been considered as nodules all well-defined and relatively homogeneous areas with hyper attenuation in the arterial phase and hypo-iso attenuation in the portal and/or delayed phase, or with hypo-iso attenuation in the arterial phase and in the portal and/or delayed phase. Lipiodol CT permitted to recognize 65 nodules (1-5/patient, mean 1.5), namely 15 grade I, 21 grade II, 20 grade III and 9 grade IV. Multiphase CT identified 6 additional nodules in 5 patients, 5 hyper vascular and 1 hypo vascular, and better assessed the correct morphology and volume of grade I nodules. Only 4 of 6 nodules missed on Lipiodol CT showed oily agent uptake after a new chemo embolization session. Moreover after retreatment, carried out in 6 of 9 patients with grade I uptake (11 nodules in all), it has been found persistence of the grade I pattern in 5 nodules, grade II in 5, and grade III in 1. Lipiodol CT may miss liver nodules and underestimate the volume of nodules with poor uptake. Though Lipiodol CT should still be considered slightly more sensitive than multiphase CT, in the general opinion this

  5. SU-E-I-93: Improved Imaging Quality for Multislice Helical CT Via Sparsity Regularized Iterative Image Reconstruction Method Based On Tensor Framelet

    International Nuclear Information System (INIS)

    Nam, H; Guo, M; Lee, K; Li, R; Xing, L; Gao, H

    2014-01-01

    Purpose: Inspired by compressive sensing, sparsity regularized iterative reconstruction method has been extensively studied. However, its utility pertinent to multislice helical 4D CT for radiotherapy with respect to imaging quality, dose, and time has not been thoroughly addressed. As the beginning of such an investigation, this work carries out the initial comparison of reconstructed imaging quality between sparsity regularized iterative method and analytic method through static phantom studies using a state-of-art 128-channel multi-slice Siemens helical CT scanner. Methods: In our iterative method, tensor framelet (TF) is chosen as the regularization method for its superior performance from total variation regularization in terms of reduced piecewise-constant artifacts and improved imaging quality that has been demonstrated in our prior work. On the other hand, X-ray transforms and its adjoints are computed on-the-fly through GPU implementation using our previous developed fast parallel algorithms with O(1) complexity per computing thread. For comparison, both FDK (approximate analytic method) and Katsevich algorithm (exact analytic method) are used for multislice helical CT image reconstruction. Results: The phantom experimental data with different imaging doses were acquired using a state-of-art 128-channel multi-slice Siemens helical CT scanner. The reconstructed image quality was compared between TF-based iterative method, FDK and Katsevich algorithm with the quantitative analysis for characterizing signal-to-noise ratio, image contrast, and spatial resolution of high-contrast and low-contrast objects. Conclusion: The experimental results suggest that our tensor framelet regularized iterative reconstruction algorithm improves the helical CT imaging quality from FDK and Katsevich algorithm for static experimental phantom studies that have been performed

  6. CT analyses of the location of the maxillary third molar in relation to panoramic radiographic appearance

    International Nuclear Information System (INIS)

    Obayashi, Naofumi; Ariji, Yoshiko; Goto, Masakazu; Izumi, Masahiro; Naitoh, Munetaka; Kurita, Kenichi; Shimozato, Kazuo; Ariji, Eiichiro

    2009-01-01

    We compared the relationship between anatomical structures analyzed by panoramic radiographs and CT images of uninfected impacted maxillary third molars and investigated the pathway of infection originating from pericoronitis of maxillary third molars. Patients (n=62) with uninfected impacted maxillary third molars and patients (n=8) with odontogenic infection originating from pericoronitis of the maxillary third molars were selected from an image database. CT and panoramic images were evaluated separately by an oral surgeon and a radiologist for the vertical position of the tooth, the presence of bone around the crown, proximity to the maxillary sinus, visibility of masticatory muscles, and mesiodistal and buccopalatal inclinations. In uninfected patients, a significant correlation was observed between the vertical positions evaluated by the two methods. Of the third molars, 79 (63.7%) were identified as vertical type on both panoramic and CT images. Regarding the maxillary sinus, of the 19 molars classified as the separate type on panoramic images, 2 (10.5%) were identified as the close type on CT. CT examination revealed the involvement of buccal cortical plates and the buccal space in the majority of infected patients. CT images revealed that 94 molars (75.8%) showed vertical type on the buccopalatal inclination and that 45 impacted molars (36.3%) showed bone defects in the buccal area. Infections originating from pericoronitis of the maxillary third molar showed involvement of the buccal cortical plates, the buccal space, and other spaces, which were clearly depicted on CT images. (author)

  7. Evaluation of the retrospective ECG-gated helical scan using half-second multi-slice CT. Motion phantom study for volumetry

    International Nuclear Information System (INIS)

    Yamamoto, Shuji; Matsumoto, Takashi; Nakanishi, Shohzoh; Hamada, Seiki; Takahei, Kazunari; Naito, Hiroaki; Ogata, Yuji

    2002-01-01

    ECG synchronized technique on multi-slice CT provide the thinner (less 2 mm slice thickness) and faster (0.5 sec/rotation) scan than that of the single detector CT and can acquire the coverage of the entire heart volume within one breath-hold. However, temporal resolution of multi-slice CT is insufficient on practical range of heart rate. The purpose of this study was to evaluate the accuracy of volumetry on cardiac function measurement in retrospective ECG-gated helical scan. We discussed the influence of the degradation of image quality and limitation of the heart rate in cardiac function measurement (volumetry) using motion phantom. (author)

  8. Radiation dose and cancer risk estimates in helical CT for pulmonary tuberculosis infections

    Directory of Open Access Journals (Sweden)

    Adeleye Bamise

    2017-12-01

    Full Text Available The preference for computed tomography (CT for the clinical assessment of pulmonary tuberculosis (PTB infections has increased the concern about the potential risk of cancer in exposed patients. In this study, we investigated the correlation between cancer risk and radiation doses from different CT scanners, assuming an equivalent scan protocol. Radiation doses from three 16-slice units were estimated using the CT-Expo dosimetry software version 2.4 and standard CT scan protocol for patients with suspected PTB infections. The lifetime risk of cancer for each scanner was determined using the methodology outlined in the BEIR VII report. Organ doses were significantly different (P < 0.05 between the scanners. The calculated effective dose for scanner H2 is 34% and 37% higher than scanners H3 and H1 respectively. A high and statistically significant correlation was observed between estimated lifetime cancer risk for both male (r2 = 0.943, P < 0.05 and female patients (r2 = 0.989, P < 0.05. The risk variation between the scanners was slightly higher than 2% for all ages but was much smaller for specific ages for male and female patients (0.2% and 0.7%, respectively. These variations provide an indication that the use of a scanner optimizing protocol is imperative.

  9. Intraductal papillary mucinous neoplasms of the pancreas: Correlation of helical CT features with pathologic findings

    International Nuclear Information System (INIS)

    Liu Yu; Lin Xiaozhu; Upadhyaya, Manavendra; Song Qi; Chen Kemin

    2010-01-01

    Objective: To evaluate the CT features of intraductal papillary mucinous neoplasms of the pancreas (IPMNs), and to compare with pathological findings in order to identify CT features that can be helpful in differentiating benign IPMNs from malignant IPMNs. Materials and methods: The CT findings in 25 patients were reviewed for tumor location, tumor type, dilatation of the main pancreatic duct (MPD), MPD involvement, mural node or solid attenuating component, tumor size in branch duct or mixed duct type, dilatation of common bile duct (CBD) and invasion of surrounding structures. The data was subjected to Chi-Square Tests or Fisher's Exact Test using SPSS13.0 software with p value < 0.05 indicating significant statistical difference. Results: Presence of mural node or solid enhancing component, size of mural node or solid enhancing component ≥7 mm, dilatation of CBD was more common in malignant IPMNs (p < 0.05). None of tumor location, tumor type, dilatation of MPD, MPD involvement, tumor size, and invasion of surrounding structures was statistically significant in differentiating benign from malignant IPMNs. Conclusions: CT features suggestive of malignant or invasive IPMNs include presence of mural node or solid enhancing component, size of mural node or solid enhancing component ≥7 mm, and dilatation of CBD.

  10. Radiation dose and cancer risk estimates in helical CT for pulmonary tuberculosis infections

    Science.gov (United States)

    Adeleye, Bamise; Chetty, Naven

    2017-12-01

    The preference for computed tomography (CT) for the clinical assessment of pulmonary tuberculosis (PTB) infections has increased the concern about the potential risk of cancer in exposed patients. In this study, we investigated the correlation between cancer risk and radiation doses from different CT scanners, assuming an equivalent scan protocol. Radiation doses from three 16-slice units were estimated using the CT-Expo dosimetry software version 2.4 and standard CT scan protocol for patients with suspected PTB infections. The lifetime risk of cancer for each scanner was determined using the methodology outlined in the BEIR VII report. Organ doses were significantly different (P < 0.05) between the scanners. The calculated effective dose for scanner H2 is 34% and 37% higher than scanners H3 and H1 respectively. A high and statistically significant correlation was observed between estimated lifetime cancer risk for both male (r2 = 0.943, P < 0.05) and female patients (r2 = 0.989, P < 0.05). The risk variation between the scanners was slightly higher than 2% for all ages but was much smaller for specific ages for male and female patients (0.2% and 0.7%, respectively). These variations provide an indication that the use of a scanner optimizing protocol is imperative.

  11. Chronological changes in the CT appearance of experimental radiofrequency thalamic lesions in dogs

    International Nuclear Information System (INIS)

    Ebisutani, Daizo; Makino, Akira; Matsumoto, Keizo; Ii, Kunio

    1987-01-01

    The location and extent of thalamic lesions following thalamotomy have been determined by the monopolar radiofrequency method. They can sometimes be identified in CT images as low-density areas, but also exceptionally high-density areas. However, this low-density area changes with time from a larger one in the acute stage to a smaller spot in the chronic stage, and sometimes it disappears within three months after the operation. It is the purpose of this study to elucidate the proper timing for the scanning for the anatomical mapping of the lesion in chronologically varying images of the lesions. Stereotactic experimental radiofrequency lesions were created in the thalamus of 35 mongrel dogs at 70 deg C for 120 sec. CT images of the brain were obtained at Days 0, 3, 7, 10, 14, 21 and 60. The lesions of the specimens and CT images tended to grow from Day 0 to Day 3, and then to grow smaller to Day 60. The area of the thalamus was measured in each specimen by means of coronal cutting. The thalamus of the lesion side was swollen from Day 0 to Day 10, but it became almost equal to that of the non-lesion side between Day 14 and Day 21. Then, the thalamus of the lesion side became atrophic. The mass effects with a ventricular deformity and a midline shift on CT images were diminished at Day 14 in most cases. The lesion areas at Day 14 corresponded to the contrast-enhanced area more than to that of the plain CT histologically. These results suggest that a lesion demonstrated by CE-CT scans at Day 14 would be suitable for anatomical mapping. (author)

  12. Multi-detector row helical CT of the liver. Quantitative assessment of iodine concentration of intravenous contrast material on multiphasic CT. A prospective randomized study

    International Nuclear Information System (INIS)

    Tsurusaki, Masakatsu; Sugimoto, Koji; Fujii, Masahiko; Sugimura, Kazuro

    2004-01-01

    The purpose of this study was to assess the quantitative effects of contrast material concentration on hepatic parenchymal and vascular enhancement in multiphasic computed tomography (CT), using multi-detector row helical CT. We designed a prospective randomized study to test two different concentrations of contrast material on five phasic scans of the liver. One hundred patients were randomly assigned to two groups: an iodine concentration of 300 mg/mL in group A and 370 mg/mL in group B. All patients received a fixed volume of 100 mL at a 4 mL/sec injection rate. Enhancement values for the hepatic parenchyma and aorta at three levels (upper, middle, and lower level of the liver), and values for portal and hepatic veins were statistically compared between the two groups. Hepatic parenchymal enhancement values at all levels of the liver in portal phase (PP) and equilibrium phase (EP) were significantly higher in group B than in group A (p<0.01). Aortic enhancement values at two levels of the liver (middle and lower) in early hepatic arterial phase (EAP) were significantly higher in group B than in group A (p<0.05), however, there was no significant difference between groups A and B in aortic enhancement during the delayed hepatic arterial phase (DAP). Portal and hepatic venous enhancement values in PP and EP were significantly higher in group B than in group A (p<0.01). On multiphasic dynamic CT, the use of a higher iodine concentration of contrast material results in higher hepatic parenchymal enhancement and aortic enhancement, as well as higher portal and hepatic venous enhancement. (author)

  13. Unenhanced helical CT in the evaluation of the urinary tract in children and young adults following urinary tract reconstruction: comparison with sonography

    Energy Technology Data Exchange (ETDEWEB)

    Myers, M.T.; Elder, J.S.; Sivit, C.J.; Applegate, K.E. [Dept. of Radiology, Rainbow Babies and Children' s Hospital, Cleveland, OH (United States)

    2001-03-01

    Purpose. To compare the accuracy of unenhanced, helical CT with sonography for the detection of complications of urinary tract reconstruction. Materials and methods. Forty-six kidneys in 24 patients were examined with CT and sonography. All scans were assessed for ease of renal visualization, presence of renal, ureteral, and bladder calculi, renal scars, hydronephrosis, and abdominal wall hernia. The results of both imaging modalities were independently reported. Results. CT provided excellent visualization of all 46 kidneys, while sonography provided poor visualization of 8 kidneys (17 %) (P < 0.001). CT detected calculi in 10 kidneys, 1 ureter, and 7 bladders. Sonography detected calculi in only 2 kidneys, and 2 bladders. Overall, CT detected significantly more calculi than US (18 vs 4, P = 0.01). CT detected scarring in 15 kidneys, while sonography detected scarring in 10. Hydronephrosis was detected in 6 kidneys by CT and in 8 kidneys by sonography. Three abdominal wall hernias were seen at CT that were not seen at sonography. Conclusion. CT is superior to sonography for the detection of urinary tract calculi and renal scarring. CT will demonstrate abdominal wall hernias that are unsuspected. (orig.)

  14. Dual-phase helical CT using bolus triggering technique: optimization of transition time

    International Nuclear Information System (INIS)

    Choi, Young Ho; Kim, Tae Kyoung; Park, Byung Kwan; Koh, Young Hwan; Han, Joon Koo; Choi, Byung Ihn

    1999-01-01

    To optimize the transition time between the triggering point in monitoring scanning and the initiation of diagnostic hepatic arterial phase (HAP) scanning in hepatic spiral CT, using a bolus triggering technique. One hundred consecutive patients with focal hepatic lesion were included in this study. Patients were randomized into two groups. Transition times of 7 and 11 seconds were used in group 1 and 2, respectively. In all patients, bolus triggered HAP spiral CT was obtained using a semi-automatic bolus tracking program after the injection of 120mL of non-ionic contrast media at a rate of 3mL/sec. When aortic enhancement reached 90 HU, diagnostic HAP scanning began after a given transition time. From images of group 1 and group 2, the degree of parenchymal enhancement of the liver and tumor-to-liver attenuation difference were measured. Also, for qualitative analysis, conspicuity of the hepatic artery and hypervascular tumor was scored and analyzed. Hepatic parenchymal enhancement on HAP was 12.07 + /-6.44 HU in group 1 and 16.03 + /-5.80 HU in group 2 (p .05). In the evaluation of conspicuity of hepatic artery, there was no statistically significant difference between the two groups (p > .05). The conspicuity of hypervascular tumors in group 2 was higher than in group 1 (p < .05). HAP spiral CT using a bolus triggering technique with a transition time of 11 seconds provides better HAP images than when the transition time is 7 seconds

  15. A qualitative diagnosis of stapes lesions by helical 3-dimensional CT

    International Nuclear Information System (INIS)

    Kawaue, Akifumi; Yamanaka, Noboru; Kuki, Kiyonori; Nishimura, Michihiko

    2001-01-01

    To evaluate the usefulness of 3D-CT combined with super-selective stapes's image processing (3D-SS) for the qualitative diagnosis of stapes lesions, a new parameter, the crus index, was designed and applied to CT image diagnosis of conductive hearing loss. The crus index was designed as a new parameter indicating the average of changing rate of cross section area of crus image when the lower thresholed of CT window width reduced by 100 H.U.. The crus index was calculated with 3D-SS in 5 ears with otosclerosis, in 5 ears with eroded long process of incus or crus of stapes, an ear with facial neurinoma (susp), an ear with soft density tissue on only stapes and 6 control ears and the diagnostic usefulness was evaluated as comparing the intra-/post-operative diagnosis. The crus index was significantly higher in ears with eroded long process of incus or crus of stapes (3.58+1.36) than otosclerosis (1.33+0.35) or controls (1.44+0.3). These data suggest that the crus index using 3D-SS may be a useful parameter in diagnosing conductive hearing loss. (author)

  16. Pericardial sinuses and recesses effusion of 16-slice helical CT imaging and anatomic correlation

    International Nuclear Information System (INIS)

    Lu Chunyan; Yang Zhigang; Zhou Xiangping; Yu Jianqun; Zhu Jie; Yang Kaiqing

    2007-01-01

    Objective: To evaluate the CT features and implications of the pericardial sinuses and recesses effusion by combining the sectional cadavers and 16 multi-slice CT (MSCT) reformation. Methods: The anatomy and communication of the pericardial sinuses and recesses on the axial, coronal and saggital sectional cadavers (respectively 1 case), and the morphologic features on MSCT reformatted images in 104 patients were observed. The detection rate of effusion was analyzed. Results: The sectional cadavers and CT images showed that the pericardial sinuses and recesses were formed by the reflections of the pericardium on the root of the great vessels. The detection rate of the sinuses and recesses was lower in small effusion than in moderate and large effusion (P<0.05). The superior aortic recess was the most common recess for pericardial effusion. Conclusion: The MSCT reformatted images can show the morphologic features of pericardial sinuses and recesses effusion and communications with the pericardial cavity, help differentiate pericardial effusion from other mediastinal or pericardial lesions. (authors)

  17. Bilateral subacromial bursitis with macroscopic rice bodies: Ultrasound, CT and MR appearance

    International Nuclear Information System (INIS)

    Law, T.C.; Chong, S.F.; Lu, P.P.; Mak, K.H.

    1998-01-01

    The radiological findings of ultrasound, CT and MR of a case of bilateral subacromial bursitis with macroscopic rice bodies is described. MRI is the investigation of choice and the intravenous gadolinium-enhanced usefulness was noted. The previous literature is also reviewed. Copyright (1998) Blackwell Science Pty Ltd

  18. Bilateral subacromial bursitis with macroscopic rice bodies: Ultrasound, CT and MR appearance

    Energy Technology Data Exchange (ETDEWEB)

    Law, T.C.; Chong, S.F.; Lu, P.P. [Kwong Wah Hospital (Hong Kong). Department of Radiology; Mak, K.H. [Kwong Wah Hospital (Hong Kong). Department of Orthopaedics and Traumatology

    1998-05-01

    The radiological findings of ultrasound, CT and MR of a case of bilateral subacromial bursitis with macroscopic rice bodies is described. MRI is the investigation of choice and the intravenous gadolinium-enhanced usefulness was noted. The previous literature is also reviewed. Copyright (1998) Blackwell Science Pty Ltd 5 refs., 1 tab., 4 figs.

  19. Comparison of helical, maximum intensity projection (MIP), and averaged intensity (AI) 4D CT imaging for stereotactic body radiation therapy (SBRT) planning in lung cancer

    International Nuclear Information System (INIS)

    Bradley, Jeffrey D.; Nofal, Ahmed N.; El Naqa, Issam M.; Lu, Wei; Liu, Jubei; Hubenschmidt, James; Low, Daniel A.; Drzymala, Robert E.; Khullar, Divya

    2006-01-01

    Background and Purpose: To compare helical, MIP and AI 4D CT imaging, for the purpose of determining the best CT-based volume definition method for encompassing the mobile gross tumor volume (mGTV) within the planning target volume (PTV) for stereotactic body radiation therapy (SBRT) in stage I lung cancer. Materials and methods: Twenty patients with medically inoperable peripheral stage I lung cancer were planned for SBRT. Free-breathing helical and 4D image datasets were obtained for each patient. Two composite images, the MIP and AI, were automatically generated from the 4D image datasets. The mGTV contours were delineated for the MIP, AI and helical image datasets for each patient. The volume for each was calculated and compared using analysis of variance and the Wilcoxon rank test. A spatial analysis for comparing center of mass (COM) (i.e. isocenter) coordinates for each imaging method was also performed using multivariate analysis of variance. Results: The MIP-defined mGTVs were significantly larger than both the helical- (p 0.001) and AI-defined mGTVs (p = 0.012). A comparison of COM coordinates demonstrated no significant spatial difference in the x-, y-, and z-coordinates for each tumor as determined by helical, MIP, or AI imaging methods. Conclusions: In order to incorporate the extent of tumor motion from breathing during SBRT, MIP is superior to either helical or AI images for defining the mGTV. The spatial isocenter coordinates for each tumor were not altered significantly by the imaging methods

  20. Appearance of untreated bone metastases from breast cancer on FDG PET/CT: importance of histologic subtype

    Energy Technology Data Exchange (ETDEWEB)

    Dashevsky, Brittany Z.; Parsons, Molly [Weill Cornell Medical College, Department of Radiology, New York, NY (United States); Goldman, Debra A.; Goenen, Mithat [Memorial Sloan-Kettering Cancer Center, Department of Epidemiology and Biostatistics, New York, NY (United States); Corben, Adriana D. [Memorial Sloan-Kettering Cancer Center, Department of Pathology, New York, NY (United States); Jochelson, Maxine S.; Ulaner, Gary A. [Weill Cornell Medical College, Department of Radiology, New York, NY (United States); Memorial Sloan-Kettering Cancer Center, Department of Radiology, New York, NY (United States); Hudis, Clifford A. [Memorial Sloan-Kettering Cancer Center, Department of Medicine, New York, NY (United States); Morrow, Monica [Memorial Sloan-Kettering Cancer Center, Department of Surgery, New York, NY (United States)

    2015-10-15

    To determine if the histology of a breast malignancy influences the appearance of untreated osseous metastases on FDG PET/CT. This retrospective study was performed under IRB waiver. Our Hospital Information System was screened for breast cancer patients who presented with osseous metastases, who underwent FDG PET/CT prior to systemic therapy or radiotherapy from 2009 to 2012. Patients with invasive ductal carcinoma (IDC), invasive lobular carcinoma (ILC), or mixed ductal/lobular (MDL) histology were included. Patients with a history of other malignancies were excluded. PET/CT was evaluated, blinded to histology, to classify osseous metastases on a per-patient basis as sclerotic, lytic, mixed lytic/sclerotic, or occult on CT, and to record SUVmax for osseous metastases on PET. Following screening, 95 patients who met the inclusion criteria (74 IDC, 13 ILC, and 8 MDL) were included. ILC osseous metastases were more commonly sclerotic and demonstrated lower SUVmax than IDC metastases. In all IDC and MDL patients with osseous metastases, at least one was FDG-avid. For ILC, all patients with lytic or mixed osseous metastases demonstrated at least one FDG-avid metastasis; however, in only three of seven patients were sclerotic osseous metastases apparent on FDG PET. The histologic subtype of breast cancer affects the appearance of untreated osseous metastases on FDG PET/CT. In particular, non-FDG-avid sclerotic osseous metastases were more common in patients with ILC than in patients with IDC. Breast cancer histology should be considered when interpreting non-FDG-avid sclerotic osseous lesions on PET/CT, which may be more suspicious for metastases (rather than benign lesions) in patients with ILC. (orig.)

  1. Appearance of untreated bone metastases from breast cancer on FDG PET/CT: importance of histologic subtype

    International Nuclear Information System (INIS)

    Dashevsky, Brittany Z.; Parsons, Molly; Goldman, Debra A.; Goenen, Mithat; Corben, Adriana D.; Jochelson, Maxine S.; Ulaner, Gary A.; Hudis, Clifford A.; Morrow, Monica

    2015-01-01

    To determine if the histology of a breast malignancy influences the appearance of untreated osseous metastases on FDG PET/CT. This retrospective study was performed under IRB waiver. Our Hospital Information System was screened for breast cancer patients who presented with osseous metastases, who underwent FDG PET/CT prior to systemic therapy or radiotherapy from 2009 to 2012. Patients with invasive ductal carcinoma (IDC), invasive lobular carcinoma (ILC), or mixed ductal/lobular (MDL) histology were included. Patients with a history of other malignancies were excluded. PET/CT was evaluated, blinded to histology, to classify osseous metastases on a per-patient basis as sclerotic, lytic, mixed lytic/sclerotic, or occult on CT, and to record SUVmax for osseous metastases on PET. Following screening, 95 patients who met the inclusion criteria (74 IDC, 13 ILC, and 8 MDL) were included. ILC osseous metastases were more commonly sclerotic and demonstrated lower SUVmax than IDC metastases. In all IDC and MDL patients with osseous metastases, at least one was FDG-avid. For ILC, all patients with lytic or mixed osseous metastases demonstrated at least one FDG-avid metastasis; however, in only three of seven patients were sclerotic osseous metastases apparent on FDG PET. The histologic subtype of breast cancer affects the appearance of untreated osseous metastases on FDG PET/CT. In particular, non-FDG-avid sclerotic osseous metastases were more common in patients with ILC than in patients with IDC. Breast cancer histology should be considered when interpreting non-FDG-avid sclerotic osseous lesions on PET/CT, which may be more suspicious for metastases (rather than benign lesions) in patients with ILC. (orig.)

  2. Ectopic origin of bronchial arteries: assessment with multidetector helical CT angiography

    International Nuclear Information System (INIS)

    Hartmann, Ieneke J.C.; Remy-Jardin, Martine; Menchini, Laura; Teisseire, Antoine; Khalil, Chadi; Remy, Jacques

    2007-01-01

    The purpose of this study was to determine non-invasively the frequency of ectopic bronchial arteries (BA) (i.e., bronchial arteries originating at a level of the descending aorta other than T5-T6 or from any aortic collateral vessel) on multidetector-row CT angiograms (CTA) obtained in patients with hemoptysis. Over a 5-year period (2000-2005), 251 consecutive patients with hemoptysis underwent multidetector-row CT angiography of the thorax. From this population, 37 patients were excluded because of a suboptimal CTA examination (n = 19), the presence of extensive mediastinal disease (n = 15) or severe chest deformation (n = 3) precluding any precise analysis of the bronchial arteries at CTA. Our final study group included 214 patients who underwent a thin-collimated CT angiogram (contrast agent: 300 to 350 mg/ml) on a 4- (n = 56), 16- (n = 119) and 64- (n = 39) detector-row scanner. The site of origin and distribution of bronchial arteries were analyzed on transverse CT scans, maximum intensity projections and volume-rendered images. The site of the ostium of a bronchial artery was coded as orthotopic when the artery originated from the descending aorta between the levels of the fifth and sixth thoracic vertebrae; all other bronchial arteries were considered ectopic. From the studied population, 137 (64%) patients had only orthotopic bronchial arteries, whereas 77 patients (36%) had at least one bronchial artery of ectopic origin. A total of 147 ectopic arteries were depicted, originating as common bronchial trunks (n = 23; 19%) or isolated right or left bronchial arteries (n = 101; 81%). The most frequent sites of origin of the 124 ostiums were the concavity of the aortic arch (92/124; 74%), the subclavian artery (13/124; 10.5%) and the descending aorta (10/124; 8.5%). The isolated ectopic bronchial arteries supplied the ipsilateral lung in all but three cases. Bronchial artery embolization was indicated in 26 patients. On the basis of CTA information, (1

  3. Renal Capsular Leiomyoma: Report of a Case with Unusual CT Appearance

    International Nuclear Information System (INIS)

    Mak, C.W.; Chou, C.K.; Tzeng, W.S.

    2006-01-01

    Clinically symptomatic renal capsular leiomyomas are rare. Previous research has shown that these tumors are usually well-defined cystic lesions, solid lesions, or a mixture of the two. We report an unusual case of renal capsular leiomyoma which was well defined by ultrasonography, but lacked a well-defined edge in CT. The reason for the absence of a well-defined tumor edge is probably due to degeneration in certain parts of the tumor resulting in a different degree of enhancement. Thus, the possibility of renal capsular leiomyoma should be included in the differential diagnosis whenever a renal mass is found, especially when either CT or ultrasonography shows that the tumor has a smooth, well-defined contour

  4. Renal Capsular Leiomyoma: Report of a Case with Unusual CT Appearance

    Energy Technology Data Exchange (ETDEWEB)

    Mak, C.W.; Chou, C.K.; Tzeng, W.S. [Chi-Mei Medical Center, Yung-Kang Campus, Tainan, Taiwan (China). Dept. of Radiology

    2006-09-15

    Clinically symptomatic renal capsular leiomyomas are rare. Previous research has shown that these tumors are usually well-defined cystic lesions, solid lesions, or a mixture of the two. We report an unusual case of renal capsular leiomyoma which was well defined by ultrasonography, but lacked a well-defined edge in CT. The reason for the absence of a well-defined tumor edge is probably due to degeneration in certain parts of the tumor resulting in a different degree of enhancement. Thus, the possibility of renal capsular leiomyoma should be included in the differential diagnosis whenever a renal mass is found, especially when either CT or ultrasonography shows that the tumor has a smooth, well-defined contour.

  5. Congenital heart diseases: post-operative appearance on multi-detector CT - a pictorial essay

    Energy Technology Data Exchange (ETDEWEB)

    Tomasian, Anderanik; Malik, Sachin; Shamsa, Kamran; Krishnam, Mayil S. [UCLA Medical Center, Department of Radiological Science, Los Angeles, CA (United States)

    2009-12-15

    Echocardiography is considered as an initial imaging modality of choice in patients with congenital heart disease (CHD), and magnetic resonance (MR) imaging is preferred for detailed functional information. Multi-detector computed tomography (CT) plays an important role in clinical practice in assessing post-operative morphological and functional information of patients with complex CHD when echocardiography and MR imaging are not contributory. Radiologists should understand and become familiar with the complex morphology and physiology of CHD, as well as with various palliative and corrective surgical procedures performed in these patients, to obtain CT angiograms with diagnostic quality and promptly recognise imaging features of normal post-operative anatomy and complications of these complex surgeries. (orig.)

  6. Mediastinal and heart wall invasion by actinomycosis: CT and MRI appearances

    International Nuclear Information System (INIS)

    Fisch, C.; Schmutz, G.R.; Benko, A.J.; Kastler, B.

    1994-01-01

    Widespread use of antibiotics facilitates the development of some uncommon chronic infections such as actinomycosis. The clinical and radiographic findings overlap those of other inflammatory and neoplastic conditions. With a review of the literature, we report the CT and MRI findings in a case of thoracic actinomycosis, presenting with right ventricular failure caused by heart involvement. CT was helpful in identifying the mediastinal extent of the disease and in demonstrating the absence of pulmonary involvement. MRI, however, offered complementary information, especially in assessing heart involvement without the need for intravenous contrast media. On T2-weighted images the mediastinal process was noted to be of relatively low signal intensity, possibly indicating its benign nature. The association with heart involvement was suggestive of thoracic actinomycosis. (orig.)

  7. Littoral cell angioma of the spleen: CT and MR imaging appearance

    Energy Technology Data Exchange (ETDEWEB)

    Schneider, G.; Uder, M.; Altmeyer, K.; Gruber, M.; Kramann, B. [Univ. Hospital Saarland University, Homburg/Saar (Germany). Dept. of Diagnostic Radiology; Bonkhoff, H. [Department of Pathology, University Hospital, Saarland University, D-66421 Homburg/Saar (Germany)

    2000-09-01

    We report a case of littoral cell angioma (LCA) of the spleen, a recently described splenic pathology, which imaging characteristics and pathologic morphology have been discussed only by a few authors. The imaging findings in unenhanced and contrast-enhanced MRI and CT as well as histologic specimen are presented. Diagnosis was made after elective splenectomy. Differential diagnosis of splenic tumors as well as the imaging findings in this particular case are discussed. (orig.)

  8. Diagnostic value of dual section helical CT in suspected acute pulmonary embolism

    International Nuclear Information System (INIS)

    Marangoni, Alberto A.; Torrecillas, Maria D.; Marchegiani, Silvio H.; Surur, Alberto

    2003-01-01

    Purpose: To asses the role of Dual Section Helical Computed Tomography (DSHCT) in patients with clinically suspected acute pulmonary embolism (APE). Material and Methods: A retrospective evaluation of 102 patients (57 male, 45 female; age range: 30-83 years; mean: 56 years) with high suspicion of APE studied by DSHCT, was carried out. From the medical records we analyzed clinical parameters, blood gases, D-dimer, risk factors and other imaging examinations. US Doppler of the inferior limbs was performed in 58/102 patients (57%). Results. 52 patients (51%) had APE on DSHCT. Scans of the other 50 patients (49%) were negative for APE. In 39/50 cases (78%) without evidence of APE, DSHCT detected ancillary thoracic findings such as atelectasia (n=11), pulmonary consolidation/edema (n=10), interstitial lung disease (n=8), pleural effusion (n=6), emphysema (n=2), nodules (n=2). 11 cases (22%) DSHCT showed no abnormal features. In this group, with persistent clinical symptoms, angio MRI showed 2 additional cases of APE (false negatives on DSHCT). On DSHCT 51/52 patients (98%) with APE showed satisfactory filling of iodinate contrast in segmental pulmonary arteries, and 45/52 patients (87%) in sub segmental arteries. On DSHCT 36 patients showed bilateral APE, and 7 had isolated peripheral APE. In 7/12 patients DSHCT demonstrated deep venous thrombosis (DVT) of the inferior limbs. In other 27/58 cases (47%) US Doppler was positive for DVT. Conclusion: DSHCT can be effectively used to rule out suspected APE and also provides additional information in patients without APE. In addition DSHCT also contributes to demonstrate deep venous thrombosis. (author)

  9. Hereditary haemorrhagic telangiectasia: study of hepatic vascular alterations with multi-detector row helical CT and reconstruction programs

    International Nuclear Information System (INIS)

    Memeo, Maurizio; Stabile Ianora, Amato Antonio; Scaldapane, Arnaldo; Rotondo, Antonio; Angelelli, Giuseppe; Suppressa, Patrizia; Cirulli, Anna; Sabba', Carlo

    2005-01-01

    Purpose: To evaluate hepatic alterations in patients affected by Hereditary Haemorrhagic Telangiectasia (HHT) by using multidetector row helical CT (MDCT) and new reconstruction programs. Materials and methods: An MDCT multiphasic study of the liver was performed in 105 consecutive patients: 89 considered to be affected by HHT and 16 with suspicion of disease alone. The scan delay was determined by using a test bolus of contrast material. The CT examination was performed with a triphasic technique (double arterial phase and portal venous phase). multiplanar and angiographic reconstructions were then obtained, and the images checked for the presence of shunts, hepatic perfusion disorders, vascular lesions (telangiectasis and large confluent vascular masses), indirect signs of portal hypertension, and anatomical vascular variants. Results: Hepatic vascular alterations were found in 78/105 cases (67/89) patients affected by HHT and 11/16 patients with clinical suspicion alone). Therefore HHT diagnosis was excluded in 5 patients. 78/100 (78%) patients with HHT had intrahepatic vascular alterations: arterioportal shunts in 40/78 (51.2%) arteriosystemic shunts in 16/78 (20.5%) and both shunt types in 22/78 (28.3%). Intraparenchymal perfusion disorders were found in 46/78 (58.9%) patients. Telangiectasis were recognised in 50/78 (64.1%) patients. Large confluent vascular masses (LCVMs) were identified in 20/78 (25.6%) patients. indirect signs of portal hypertension were found in 46/78 (58.9%) cases. Variant hepatic arterial anatomy was present in 38/100 cases (38%). Conclusions: Multiphasic MDCT and the new reconstruction programs enable the identification and characterisation of the complex vascular alterations typical of HHT [it

  10. Detection and localization of acute upper and lower gastrointestinal (GI) bleeding with arterial phase multi-detector row helical CT

    Energy Technology Data Exchange (ETDEWEB)

    Jaeckle, T.; Stuber, G.; Hoffmann, M.H.K.; Jeltsch, M.; Schmitz, B.L.; Aschoff, A.J. [University Hospital of Ulm, Diagnostic and Interventional Radiology, Ulm (Germany)

    2008-07-15

    The purpose of this study was to evaluate the accuracy of multi-detector row helical CT (MDCT) for detection and localization of acute upper and lower gastrointestinal (GI) hemorrhage or intraperitoneal bleeding. Thirty-six consecutive patients with clinical signs of acute bleeding underwent biphasic (16- or 40-channel) MDCT. MDCT findings were correlated with endoscopy, angiography or surgery. Among the 36 patients evaluated, 26 were examined for GI bleeding and 10 for intraperitoneal hemorrhage. Confirmed sites of GI bleeding were the stomach (n = 5), duodenum (n = 5), small bowel (n = 6), large bowel (n = 8) and rectum (n = 2). The correct site of bleeding was identifiable on MDCT in 24/26 patients with GI bleeding. In 20 of these 24 patients, active CM extravasation was apparent during the exam. Among the ten patients with intraperitoneal hemorrhage, MDCT correctly identified the bleeding source in nine patients. Our findings suggest that fast and accurate localization of acute gastrointestinal and intraperitoneal bleeding is achievable on MDCT. (orig.)

  11. Detection and localization of acute upper and lower gastrointestinal (GI) bleeding with arterial phase multi-detector row helical CT

    International Nuclear Information System (INIS)

    Jaeckle, T.; Stuber, G.; Hoffmann, M.H.K.; Jeltsch, M.; Schmitz, B.L.; Aschoff, A.J.

    2008-01-01

    The purpose of this study was to evaluate the accuracy of multi-detector row helical CT (MDCT) for detection and localization of acute upper and lower gastrointestinal (GI) hemorrhage or intraperitoneal bleeding. Thirty-six consecutive patients with clinical signs of acute bleeding underwent biphasic (16- or 40-channel) MDCT. MDCT findings were correlated with endoscopy, angiography or surgery. Among the 36 patients evaluated, 26 were examined for GI bleeding and 10 for intraperitoneal hemorrhage. Confirmed sites of GI bleeding were the stomach (n = 5), duodenum (n = 5), small bowel (n = 6), large bowel (n = 8) and rectum (n = 2). The correct site of bleeding was identifiable on MDCT in 24/26 patients with GI bleeding. In 20 of these 24 patients, active CM extravasation was apparent during the exam. Among the ten patients with intraperitoneal hemorrhage, MDCT correctly identified the bleeding source in nine patients. Our findings suggest that fast and accurate localization of acute gastrointestinal and intraperitoneal bleeding is achievable on MDCT. (orig.)

  12. 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.

  13. The role of unenhanced helical CT in the evaluation of suspected renal colic and atypical abdominal pain in children

    International Nuclear Information System (INIS)

    Eshed, Iris; Witzling, Michaela

    2002-01-01

    Background: Urolithiasis in children has a different pattern of presentation than in adults and its incidence is lower. Unenhanced helical CT (UEHCT) for suspected urinary tract calculi in adults has high sensitivity and specificity for detecting even minute calculi. UEHCT has been proposed as a fast and sensitive method for identifying urinary stones in children. However, to our knowledge, the role of UEHCT and its value in the diagnostic work-up of urinary stones in children has not been studied. Objective: To evaluate the significance of UEHCT as a diagnostic tool for urinary stones in children. Materials and methods: We retrospectively analysed data on 20 children who underwent UEHCT during 1999-2000. Results: Findings on UEHCT were significant in establishing a diagnosis in only seven patients and only three were shown to have urinary stones. Only one significant finding was found in the group who underwent UEHCT without prior US. US performed prior to UEHCT was a significant screening tool, and when results were equivocal, UEHCT further helped in establishing diagnosis. Conclusions: We propose that US be the first imaging modality in children with suspected urolithiasis. When the result of this examination is uncertain or abnormal, UEHCT will probably add further information which will contribute to the diagnosis. (orig.)

  14. Volume-artifact reduction modality by helical CT of the anterior, middle and posterior carnial fossae. Comparison with conventional CT; Volumen-Artefakt-Reduktionstechnik mittels Spiral-CT in der vorderen, mittleren und hinteren Schaedelgrube. Vergleich mit der konventionellen kranialen CT

    Energy Technology Data Exchange (ETDEWEB)

    Dorenbeck, U.; Finkenzeller, T.; Hill, K.; Feuerbach, S.; Link, J. [Regensburg Univ. (Germany). Inst. fuer Roentgendiagnostik

    2000-04-01

    Purpose: The object of this study was to determine the extent to which a new volume-artifact reduction (VAR) modality using helical CT was able to reduce artifacts in the anterior, middle and posterior fossae in comparison with conventional CT (sequential mode). Methods: In a prospective, randomized trial, 50 patients underwent helical CT (VAR) and 50 underwent sequential CT. The results were evaluated by three radiologists; influences on image quality where scaled between 1 (no artifact) and 4 (not assessable). Eight regions of the anterior, middle and posterior fossae were evaluated. Results: On average, artifacts were scaled at 2.5 in helical CT (VAR) and 3.1 in conventional CT. Significant differences were seen at the eyeball, anterior to the petrosol bone, at the internal occipital crest, and at the level of the transverse sinus (p<0.005). Conclusions: Helical CT with the VAR modality is superior to conventional, sequential CT in the area of the anterior, middle and posterior fossae. (orig.) [German] Ziel: Das Ziel dieser Studie war herauszufinden, inwieweit ein neuer Volumen-Artefakt-Reduktionsmodus (VAR) im Spiral-CT in der vorderen, mittleren und hinteren Schaedelgrube gegenueber der Einzelschicht-CT zu einer Artefaktverringerung beitragen kann. Methoden: In einer prospektiven randomisierten Studie wurden 50 Untersuchungen mit Spiral-CT und 50 mit Einzelschicht-CT bezueglich Artefakten verglichen. Die Auswertung erfolgte durch drei Radiologen, die Bildqualitaet wurde in einer Skala zwischen 1 (kein Artefakt) und 4 (Beurteilung der Region wegen Artefakten nicht moeglich) angegeben. Acht anatomische Regionen in der vorderen, mittleren und hinteren Schaedelgrube wurden auf Beeintraechtigung durch Artefakte untersucht. Ergebnisse: Im Durchschnitt betrug die Bewertung fuer die Artefaktbeeintraechtigung beim Spiral-CT (VAR) 2,5 gegenueber 3,1 bei der Einzelschicht-CT. Der VAR-Modus ermoeglichte in der mittleren und hinteren Schaedelgrube sowie im Balbus oculi

  15. Multidetector helical CT plus superparamagnetic iron oxide-enhanced MR imaging for focal hepatic lesions in cirrhotic liver: A comparison with multi-phase CT during hepatic arteriography

    International Nuclear Information System (INIS)

    Yukisawa, Seigo; Okugawa, Hidehiro; Masuya, Yoshio; Okabe, Shinichirou; Fukuda, Hiroyuki; Yoshikawa, Masaharu; Ebara, Masaaki; Saisho, Hiromitsu

    2007-01-01

    The aim of this study was to evaluate multidetector helical computed tomography (MDCT), superparamagnetic iron oxide (SPIO)-enhanced magnetic resonance (MR) imaging, and CT arterial portography (CTAP) and CT during hepatic arteriography (CTHA) for the detection and diagnosis of hepatocellular carcinomas (HCC). This included visual correlations of MDCT and SPIO-MR imaging in the detection of HCC using receiver operating characteristic (ROC) analysis. Twenty-five patients with 57 nodular HCCs were retrospectively analyzed. A total of 200 segments, including 49 segments with 57 HCCs, were reviewed independently by three observers. Each observer read four sets of images (set 1, MDCT; set 2, unenhanced and SPIO-enhanced MR images; set 3, combined MDCT and SPIO-enhanced MR images; set 4, combined CTAP and CTHA). The mean Az values representing the diagnostic accuracy for HCCs of sets 1, 2, 3, and 4 were 0.777, 0.814, 0.849, and 0.911, respectively, and there was no significant difference between sets 3 and 4. The sensitivity of set 4 was significantly higher than those of set 3 for all the lesions and for lesions 10 mm or smaller (p < 0.05); however, for lesions larger than 10 mm, the sensitivities of the two sets were similar. No significant difference in positive predictive value and specificity was observed between set 3 and set 4. Combined MDCT and SPIO-enhanced MR imaging may obviate the need for more invasive CTAP and CTHA for the pre-therapeutic evaluation of patients with HCC more than 10 mm

  16. Coronary artery calcification detected by a mobile helical CT unit in a mass screening. The frequency and relationship to coronary risk factors and coronary artery disease

    Energy Technology Data Exchange (ETDEWEB)

    Itani, Yasutaka; Watanabe, Shigeru; Masuda, Yoshiaki [Chiba Univ. (Japan). School of Medicine; Hanamura, Kazuhisa; Asakura, Kazuhiro; Sone, Shusuke; Sunami, Yuko; Shimura, Akimitsu; Miyamoto, Tadaaki

    2001-06-01

    A strong relationship is known to exist between coronary artery disease (CAD) and coronary artery calcification (CAC) detected by CT. In this study, we investigated the frequency of CAC and the relationship between coronary risk factors, CAD and CAC in a mass screening using a mobile helical CT unit. The total number of participants was 10008 people undergoing a medical examination for lung cancer and tuberculosis using a mobile helical CT unit. We measured the CT density of the coronary artery to detect CAC. The CT density threshold for determining CAC was above +110HU. The frequency of CAC was 16.0% in the overall patient population and significantly higher in males than in females (20.6% vs 10.7%). Frequency increased with age in both genders. Hypertension and diabetes mellitus were significantly related to CAC. Smoking showed a correlation with CAC only in males. A significant relationship was observed between CAD and CAC in males. In particular, the relationship between them was strongest in males under 60 years of age. Furthermore, the odds ratio of CAC in predicting CAD increased with increasing risk factors in both genders. (author)

  17. Appearance of bony lesions on 3-D CT reconstructions: a case study in variable renderings

    Science.gov (United States)

    Mankovich, Nicholas J.; White, Stuart C.

    1992-05-01

    This paper discusses conventional 3-D reconstruction for bone visualization and presents a case study to demonstrate the dangers of performing 3-D reconstructions without careful selection of the bone threshold. The visualization of midface bone lesions directly from axial CT images is difficult because of the complex anatomic relationships. Three-dimensional reconstructions made from the CT to provide graphic images showing lesions in relation to adjacent facial bones. Most commercially available 3-D image reconstruction requires that the radiologist or technologist identify a threshold image intensity value that can be used to distinguish bone from other tissues. Much has been made of the many disadvantages of this technique, but it continues as the predominant method in producing 3-D pictures for clinical use. This paper is intended to provide a clear demonstration for the physician of the caveats that should accompany 3-D reconstructions. We present a case of recurrent odontogenic keratocyst in the anterior maxilla where the 3-D reconstructions, made with different bone thresholds (windows), are compared to the resected specimen. A DMI 3200 computer was used to convert the scan data from a GE 9800 CT into a 3-D shaded surface image. Threshold values were assigned to (1) generate the most clinically pleasing image, (2) produce maximum theoretical fidelity (using the midpoint image intensity between average cortical bone and average soft tissue), and (3) cover stepped threshold intensities between these two methods. We compared the computer lesions with the resected specimen and noted measurement errors of up to 44 percent introduced by inappropriate bone threshold levels. We suggest clinically applicable standardization techniques in the 3-D reconstruction as well as cautionary language that should accompany the 3-D images.

  18. Diagnostic difficulties in the differentiation of neurogenic tumors of the parapharyngeal space in helical CT evaluations: A case report

    International Nuclear Information System (INIS)

    Czerniewicz-Kaminska, A.; Nowicki, J.; Jazwiec, P.; Kedzierski, B.; Janeczek, T.; Wilczynski, K.; Prudlak, E.

    2005-01-01

    Computerized tomography (CT) with contrast infusion and magnetic resonance imaging (MRI) play important roles in establishing the place of origin of neurogenic tumors. In this article we do not compare these two methods, but focus on the crucial role of CT imaging in the estimation and differential diagnosis of these tumors. We present the case of a 50-year-old man with clinical symptoms of peritonsillar abscess, which appeared to be a neurogenic tumor. The images obtained were deemed ambiguous. The possibility of a parotid gland tumor or a tumor of neurogenic origin was assumed. In this case we observed atypical clinical and radiological symptoms. The final diagnosis was based on a combination of radiological, clinical, and microbiological features of the tumor. Thanks to the cooperation of many professionals, we managed to establish the diagnosis of neuroangiofibroma, which exemplifies a tumor of the borderline, including elements of the neurogenic sheath and connective and chromaffin tissue. (author)

  19. MRI and CT appearances in metabolic encephalopathies due to systemic diseases in adults

    International Nuclear Information System (INIS)

    Bathla, G.; Hegde, A.N.

    2013-01-01

    The term encephalopathy refers to a clinical scenario of diffuse brain dysfunction, commonly due to a systemic, metabolic, or toxic derangement. Often the clinical evaluation is unsatisfactory in this scenario and imaging plays an important role in the diagnosis, assessment of treatment response, and prognostication of the disorder. Hence, it is important for radiologists to be familiar with the imaging features of some relatively frequently acquired metabolic encephalopathies encountered in the hospital setting. This study reviews the computed tomography (CT) and magnetic resonance imaging (MRI) features of a number of metabolic encephalopathies that occur as part of systemic diseases in adults. The following conditions are covered in this review: hypoglycaemic encephalopathy, hypoxic ischaemic encephalopathy, non-ketotic hyperglycaemia, hepatic encephalopathy, uraemic encephalopathy, hyperammonaemic encephalopathy, and posterior reversible encephalopathy syndrome. MRI is the imaging method of choice in evaluating these conditions. Due to their high metabolic activity, bilateral basal ganglia changes are evident in the majority of cases. Concurrent imaging abnormalities in other parts of the central nervous system often provide useful diagnostic information about the likely underlying cause of the encephalopathy. Besides this, abnormal signal intensity and diffusion restriction patterns on MRI and MR spectroscopy features may provide important clues as to the diagnosis and guide further management. Frequently, the diagnosis is not straightforward and typical imaging features require correlation with clinical and laboratory data for accurate assessment

  20. Lung cancer screening with low-dose helical CT in Korea: experiences at the Samsung Medical Center.

    Science.gov (United States)

    Chong, Semin; Lee, Kyung Soo; Chung, Myung Jin; Kim, Tae Sung; Kim, Hojoong; Kwon, O Jung; Choi, Yoon-Ho; Rhee, Chong H

    2005-06-01

    To determine overall detection rates of lung cancer by low-dose CT (LDCT) screening and to compare histopathologic and imaging differences of detected cancers between high- and low-risk groups, this study included 6,406 asymptomatic Korean adults with >or=45 yr of age who underwent LDCT for lung cancer screening. All were classified into high- (>or=20 pack-year smoking; 3,353) and low-risk (3,053; <20 pack-yr smoking and non-smokers) groups. We compared CT findings of detected cancers and detection rates between high- and low-risk. At initial CT, 35% (2,255 of 6,406) had at least one or more non-calcified nodule. Lung cancer detection rates were 0.36% (23 of 6,406). Twenty-one non-small cell lung cancers appeared as solid (n=14) or ground-glass opacity (GGO) (n=7) nodules. Cancer likelihood was higher in GGO nodules than in solid nodules (p<0.01). Fifteen of 23 cancers occurred in high-risk group and 8 in low-risk group (p=0.215). Therefore, LDCT screening help detect early stage of lung cancer in asymptomatic Korean population with detection rate of 0.36% on a population basis and may be useful for discovering early lung cancer in low-risk group as well as in high-risk group.

  1. Multislice helical CT analysis of small-sized airway wall thickness in smokers and patients with bronchial asthma

    International Nuclear Information System (INIS)

    Sekimura, Kenshi; Ito, Harumasa; Nakamura, Yutaka; Kobayashi, Hitoshi; Oikawa, Hirobumi; Inoue, Hiroshi; Ehara, Shigeru; Yamauchi, Kohei

    2010-01-01

    There is accumulating evidence that airway remodeling, which contributes to airway narrowing, plays a role in the pathogenesis of bronchial asthma (BA) and chronic obstructive pulmonary disease (COPD). Development of the multislice helical CT (MSCT) with improved spatial resolution has made it possible to obtain more precise imaging of small-sized airways. Small-sized airway wall-thickness was measured using the MSCT scan to analyze small-sized airways of smokers and BA patients, and examine the effects of a β 2 agonists on small-sized airway wall-thickness of BA patients. Thirty-six non-asthmatics who participated in the Health Check Program of Iwate Medical University and 25 patients with asthma were recruited. Amongst the 36 non-asthmatics were 20 healthy never-smokers and 15 smokers. The other 25 asthmatics were recruited from the outpatient clinic at Iwate Medical University. MSCT was performed and the right B10 bronchus was chosen for dimensional analysis. Airway wall thickness was expressed as a percentage of wall area (WA%). WA% of the 7 asthmatics before and 30 mim after procaterol (20μg) inspiration were compared. Small-sized airway wall thickness was significantly increased in smokers and patients with asthma compared to healthy never-smokers, when determined by MSCT. Both %V 50 and %V 25 had significant negative correlations with WA% among the healthy never-smokers and smoker population. Procaterol inspiration reduced WA% in the small airway of patients with asthma. Increase of small-sized airway thickness measured by MSCT scan may reflect peripheral obstructive lesions of smokers and BA patients. (author)

  2. Comparison of the effectiveness of different immobilization systems in different body regions using daily megavoltage CT in helical tomotherapy

    Science.gov (United States)

    Cheng, K-F

    2014-01-01

    Objective: Effective immobilization is crucial for the accurate delivery of radiotherapy. This study aimed to compare the effectiveness of the commonly used immobilization systems for different body regions using megavoltage CT (MVCT). Methods: Daily treatment set-up data from 212 patients treated by helical tomotherapy (Accuray, Sunnyvale, CA) in 6 body regions (52 head and neck, 41 chest, 38 abdomen, 36 pelvis, 18 breast and 27 cranium) were obtained. Based on a verification tool using the pre-treatment MVCT, set-up corrections for each patient were recorded. Mean systematic and random errors of lateral, longitudinal, vertical and roll directions and three-dimensional vectors were compared between immobilization systems of each region. Results: Smaller set-up deviations were observed in the Orfit system (Orfit Industries NV, Wijnegem, Belgium) of the head and neck region, while the performance of immobilization systems for the chest, abdomen and pelvis regions was similar. Larger differences were noted in the breast group, where the prone BodyFIX® system (Medical Intelligence, Medizintechnik GmbH, Schwabmünchen, Germany) was less stable than the supine VacLok® system (CIVCO Medical Solutions, Orange City, IA). Conclusion: Differences were found between the immobilization systems in the head and neck region, in which the Orfit system was relatively more effective, whereas the VacLok and BodyFIX systems performed similarly in the chest, abdomen and pelvis regions. For the breast case, the supine position with VacLok was much more stable than the prone breast technique. The results provided references for the estimation of clinical target volume–planning target volume margins. Advances in knowledge: This is the first article on comprehensive comparisons performed in immobilization systems for main body regions that provides some practical recommendations. PMID:24398111

  3. Suitability of helical multislice acquisition technique for routine unenhanced brain CT: an image quality study using a 16-row detector configuration

    Energy Technology Data Exchange (ETDEWEB)

    Hernalsteen, Danielle; Cosnard, Guy; Grandin, Cecile; Duprez, Thierry [Universite Catholique de Louvain, Cliniques Universitaires Saint-Luc, Department of Radiology and Medical Imaging, Brussels (Belgium); Robert, Annie [Public Health School, Universite Catholique de Louvain, Department of Epidemiologics and Medical Statistics, Brussels (Belgium); Vlassenbroek, Alain [CT Clinical Science, Philips Medical Systems, Cleveland, OH (United States)

    2007-04-15

    Subjective and objective image quality (IQ) criteria, radiation doses, and acquisition times were compared using incremental monoslice, incremental multislice, and helical multislice acquisition techniques for routine unenhanced brain computed tomography (CT). Twenty-four patients were examined by two techniques in the same imaging session using a 16-row CT system equipped with 0.75-width detectors. Contiguous ''native'' 3-mm-thick slices were reconstructed for all acquisitions from four detectors for each slice (4 x 0.75 mm), with one channel available per detector. Two protocols were tailored to compare: (1) one-slice vs four-slice incremental images; (2) incremental vs helical four-slice images. Two trained observers independently scored 12 subjective items of IQ. Preference for the technique was assessed by one-tailed t test and the interobserver variation by two-tailed t test. The two observers gave very close IQ scores for the three techniques without significant interobserver variations. Measured IQ parameters failed to reveal any difference between techniques, and an approximate half radiation dose reduction was obtained by using the full 16-row configuration. Acquisition times were cumulatively shortened by using the multislice and the helical modality. (orig.)

  4. Suitability of helical multislice acquisition technique for routine unenhanced brain CT: an image quality study using a 16-row detector configuration

    International Nuclear Information System (INIS)

    Hernalsteen, Danielle; Cosnard, Guy; Grandin, Cecile; Duprez, Thierry; Robert, Annie; Vlassenbroek, Alain

    2007-01-01

    Subjective and objective image quality (IQ) criteria, radiation doses, and acquisition times were compared using incremental monoslice, incremental multislice, and helical multislice acquisition techniques for routine unenhanced brain computed tomography (CT). Twenty-four patients were examined by two techniques in the same imaging session using a 16-row CT system equipped with 0.75-width detectors. Contiguous ''native'' 3-mm-thick slices were reconstructed for all acquisitions from four detectors for each slice (4 x 0.75 mm), with one channel available per detector. Two protocols were tailored to compare: (1) one-slice vs four-slice incremental images; (2) incremental vs helical four-slice images. Two trained observers independently scored 12 subjective items of IQ. Preference for the technique was assessed by one-tailed t test and the interobserver variation by two-tailed t test. The two observers gave very close IQ scores for the three techniques without significant interobserver variations. Measured IQ parameters failed to reveal any difference between techniques, and an approximate half radiation dose reduction was obtained by using the full 16-row configuration. Acquisition times were cumulatively shortened by using the multislice and the helical modality. (orig.)

  5. Dual phase helical CT versus portal venous phase CT for the detection of colorectal liver metastases: Correlation with intra-operative sonography, surgical and pathological findings

    International Nuclear Information System (INIS)

    Scott, D. John; Guthrie, J. Ashley; Arnold, Paul; Ward, Janice; Atchley, Julian; Wilson, Daniel; Robinson, Philip J.

    2001-01-01

    AIM: To assess whether dual phase helical computed tomography (DPCT) of the liver improves the detection of colorectal liver metastases compared with portal venous phase (PVP) imaging alone. MATERIALS AND METHODS: DPCT was performed in 33 consecutive patients before laparotomy for resection of colorectal liver metastases. CT comprised 8-mm slice collimation with a pitch of 1 to 1.25; imaging was commenced 20-25 and 65-70 s after the start of injection of 150 ml of contrast medium at 5 ml/s to coincide with hepatic arterial phase (HAP) and PVP contrast enhancement, respectively. Four blinded observers independently reviewed the HAP, PVP and DPCT images recording the site and size of all lesions. Alternative-free response receiver operating characteristic (AFROC) methodology was used to analyse the results, which were correlated with surgery, intra-operative ultrasound and histology. RESULTS: The mean observer sensitivities for malignant lesion detection were 75.3% for DPCT, 69.7% for PVP imaging and 66.7% for HAP imaging alone. There was a statistically significant improvement in malignant lesion detection using DPCT when compared with PVP imaging alone (P < 0.05). The mean areas under the AFROC curves were 0.84 for DPCT and 0.82 for PVP (P < 0.03) imaging alone. CONCLUSION: The detection of colorectal liver metastases was marginally better with DPCT than with PVP imaging alone, but the discovery of additional lesions did not affect the management of any of the patients in this study. Scott, D.J. et al. (2001)

  6. 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

  7. TH-E-17A-02: High-Pitch and Sparse-View Helical 4D CT Via Iterative Image Reconstruction Method Based On Tensor Framelet

    International Nuclear Information System (INIS)

    Guo, M; Nam, H; Li, R; Xing, L; Gao, H

    2014-01-01

    Purpose: 4D CT is routinely performed during radiation therapy treatment planning of thoracic and abdominal cancers. Compared with the cine mode, the helical mode is advantageous in temporal resolution. However, a low pitch (∼0.1) for 4D CT imaging is often required instead of the standard pitch (∼1) for static imaging, since standard image reconstruction based on analytic method requires the low-pitch scanning in order to satisfy the data sufficient condition when reconstructing each temporal frame individually. In comparison, the flexible iterative method enables the reconstruction of all temporal frames simultaneously, so that the image similarity among frames can be utilized to possibly perform high-pitch and sparse-view helical 4D CT imaging. The purpose of this work is to investigate such an exciting possibility for faster imaging with lower dose. Methods: A key for highpitch and sparse-view helical 4D CT imaging is the simultaneous reconstruction of all temporal frames using the prior that temporal frames are continuous along the temporal direction. In this work, such a prior is regularized through the sparsity transform based on spatiotemporal tensor framelet (TF) as a multilevel and high-order extension of total variation transform. Moreover, GPU-based fast parallel computing of X-ray transform and its adjoint together with split Bregman method is utilized for solving the 4D image reconstruction problem efficiently and accurately. Results: The simulation studies based on 4D NCAT phantoms were performed with various pitches (i.e., 0.1, 0.2, 0.5, and 1) and sparse views (i.e., 400 views per rotation instead of standard >2000 views per rotation), using 3D iterative individual reconstruction method based on 3D TF and 4D iterative simultaneous reconstruction method based on 4D TF respectively. Conclusion: The proposed TF-based simultaneous 4D image reconstruction method enables high-pitch and sparse-view helical 4D CT with lower dose and faster speed

  8. CT imaging before transcatheter aortic valve implantation (TAVI) using variable helical pitch scanning and its diagnostic performance for coronary artery disease

    Energy Technology Data Exchange (ETDEWEB)

    Matsumoto, Shunsuke; Yamada, Yoshitake; Hashimoto, Masahiro; Okamura, Teppei; Jinzaki, Masahiro [Keio University School of Medicine, Department of Diagnostic Radiology, Shinanomachi, Shinjuku-ku, Tokyo (Japan); Yamada, Minoru [Keio University School of Medicine, Research Park, Tokyo (Japan); Yashima, Fumiaki; Hayashida, Kentaro; Fukuda, Keiichi [Keio University School of Medicine, Department of Cardiology, Tokyo (Japan)

    2017-05-15

    To evaluate the effectiveness of CT before TAVI using variable helical pitch (VHP) scanning and its diagnostic performance for coronary artery disease (CAD). Sixty patients (84.4 ± 4.6 years) scheduled for TAVI underwent CT using VHP scanning with the contrast material (CM) volume calculated as scanning time x weight [kg] x 0.06 mL. Retrospective electrocardiography (ECG)-gated scanning was utilized to examine the thorax, and non-ECG-gated scanning of the abdomen immediately followed. We analyzed CT attenuation values of the coronary arteries, aorta, iliac and femoral arteries. The coronary CT angiography images were evaluated for the presence of stenosis (≥50 %); invasive coronary angiography served as a reference standard. The average attenuations of all of the arteries were greater than 400 HU. We could evaluate the peripheral access vessels and dimensions of the ascending aorta, aortic root, and aortic annulus in all patients. The average volume of CM was 38.7 ± 8.5 mL. On per-patient and vessel analysis, CT showed 91.7 % and 89.5 % sensitivity, and 91.3 % and 97.4 % negative predictive value (NPV). CT using VHP scanning with an average CM volume of 38.7 mL is useful before TAVI and had a high sensitivity and NPV in excluding obstructive CAD. (orig.)

  9. Blunt trauma to the gastrointestinal tract and mesentery: is there a role for helical CT in the decision-making process?

    International Nuclear Information System (INIS)

    Scaglione, Mariano; de Lutio di Castelguidone, Elisabetta; Scialpi, Michele; Merola, Stefanella; Diettrich, Andrea Irma; Lombardo, Patrizia; Romano, Luigia; Grassi, Roberto

    2004-01-01

    The CT diagnosis of bowel and mesenteric injuries is difficult and warrants optimal technique and skilled interpretation. We retrospectively reviewed 36 consecutive patients with blunt traumatic injuries to the bowel and mesentery at our regional level I trauma center during the past 3 years. Physical examination, laboratory, Computed tomographic (CT), and intraoperative findings were compared. Surgically proven bowel injuries (13 cases) occurred in the duodenum (three cases), ileum (two cases), jejunum (two cases), colon (three cases), and stomach (three cases). CT findings considered specific of bowel rupture were observed in 5/13 patients including: extraluminal oral contrast or luminal content extravasation (four cases) and discontinuity of hollow viscus wall (one case). In the remaining 8/13 CT findings considered suggestive of bowel injury consisted of: pneumoperitoneum (six), gas bubbles close to the injured hollow viscus (three), thickened (>4-5 mm) bowel wall (five), bowel wall hematoma (three), intraperitoneal fluid of unknown source (three). Mesenteric injury (23 cases) were surgically observed at the level of the mesenteric vessels (17 cases), legament of Treitz (two cases), gastro-duodenal artery (one case), transverse (one case) and sigmoid mesocolon (one case). CT finding considered specific of mesenteric laceration was active extravasation of contrast material from the mesenteric vessels (10 cases). CT findings suggestive of mesenteric injury (13 cases) consisted of: mesenteric hematoma (five) and/or high attenuation fluid collections, within the mesenteric root (eight) and folds (four). Helical CT is sensitive in the identification of bowel and mesenteric injury after blunt trauma providing a wide spectrum of findings. However, CT cannot be used as the sole indicator in cases with isolated thickened bowel wall, mesenteric hematoma, bowel hematoma, pneumoperitoneum or gas bubbles. Persistent, active extravasation of intravenous contrast medium from

  10. Posterior diaphragmatic defect detected on chest CT: the incidence according to age and the lateral chest radiographic appearances

    International Nuclear Information System (INIS)

    Lee, Son Youl; Choi, Yo Won; Jeon, Seok Chol; Heo, Jeong Nam; Park, Choong Ki

    2007-01-01

    We wanted to investigate the incidence of posterior diaphragmatic defect on chest CT in various age groups and its lateral chest radiographic appearances. The chest CT scans of 78 patients of various ages with posterior diaphragmatic defect were selected among 1,991 patients, and they were analyzed for the incidence of defect in various age groups, the defect location and the herniated contents. Their lateral chest radiographs were analyzed for the shape of the posterior diaphragm and the posterior costophrenic sulcus. The patients' ages ranged from 34 to 87 with the tendency of a higher incidence in the older patients. The defect most frequently involved the medial two thirds (n = 49, 50.4%) and middle one third (n = 36, 37%) of the posterior diaphragm. The retroperitoneal fat was herniated into the thorax through the defect in all patients, and sometimes with the kidney (n = 8). Lateral chest radiography showed a normal diaphragmatic contour (n = 51, 49.5%), blunting of the posterior costophrenic sulcus (n = 41, 39.8%), focal humping of the posterior diaphragm (n = 7, 6.8%), or upward convexity (n = 4, 3.9%) of the posterior costophrenic sulcus on the affected side. The posterior diaphragmatic defect discovered in asymptomatic patients who are without a history of peridiaphragmatic disease is most likely acquired, and this malady increases in incidence according to age. An abnormal contour of the posterior diaphragm or the costophrenic sulcus on a lateral chest radiograph may be a finding of posterior diaphragmatic defect

  11. A diagnostic dilemma of atypical gallbladder appearance on Tc-99m HIDA cholescintigraphy resolved with SPECT/CT.

    Science.gov (United States)

    Sood, Ravi; Murguia, Jeff; Graham, Michael M; Bushnell, David; Squires, Shayne; Laroia, Sandeep T; Bansal, Anish

    2011-02-01

    Tc-99m HIDA cholescintigraphy is the diagnostic procedure of choice for acute cholecystitis. Acute cholecystitis is associated in vast majority of the cases with cystic duct obstruction. The demonstration of presence (cystic duct patency) or absence (cystic duct obstruction) of visualization of the gallbladder on cholescintigraphy is critical to the diagnosis of acute cholecystitis. The visualization of the gallbladder rules out acute cholecystitis in most of the cases. Although, in most cases, determination of visualization or nonvisualization of gallbladder is straight forward, occasionally it can be challenging. We describe a patient with suspected acute cholecystitis, in whom an unusual appearance of the gallbladder on hepatobiliary scintigraphy was clarified with SPECT/CT, an approach that is rarely used in Tc-99m HIDA cholescintigraphy.

  12. Exploration of cervical carotid stenosis using helical CT angiography. A prospective trial on the detection of candidates for surgery in the Gujo area, Gifu

    Energy Technology Data Exchange (ETDEWEB)

    Yamakawa, Hiroyasu; Sumi, Yasuhiko [Sumi Hospital, Gifu (Japan); Kaku, Yasuhiko; Sakai, Noboru; Yamada, Hiromu

    1995-04-01

    To detect cervical carotid stenosis as a candidate for carotid endarterectomy (CEA), the authors attempted a prospective trial by exploring stenosis for one year in a rural district with a population of 20,000, employing helical CT angiography which apparently displayed three-dimensional reconstructed images of the carotid bifurcation. Thirty-three patients, 24 males and 9 females, with a mean age of 71.8 years, suffering from TIA, RIND or stroke were investigated for their carotid systems. The clinical symptoms of the patients were briefly as follows: motor weakness in 30 cases, dysarthria in 8 cases and aphasia in 4 cases; and 6 of 22 (27%) stroke cases had previously suffered an episode of TIA. The risk factors of the whole group of patients were hypertension in 13 cases, diabetes mellitus in 6, heart disease in 17, and hypercholesteremia in 4. Helical CT angiography was performed in 11 cases of TIA, 2 cases of RIND, and 16 cases of stroke. Only 3 cases of the TIA group and 3 cases of the stroke group were found to have extracranial carotid stenosis of more than 50%, which subsequently required conventional angiography. For the detection of stenosis, CT angiography was beneficial as well as conventional angiography. Finally, CEA was performed in 2 of 3 cases with severe carotid stonosis in the TIA group, while such cases in the stroke group were only observed. The above results meant that the occurrence of extracranial carotid stenosis was 6 out of 6,589 elderly inhabitants (over 60 years old), although the possible detection rate of candidates for CEA was 2 out of 20,000 population per year. (author).

  13. Exploration of cervical carotid stenosis using helical CT angiography. A prospective trial on the detection of candidates for surgery in the Gujo area, Gifu

    International Nuclear Information System (INIS)

    Yamakawa, Hiroyasu; Sumi, Yasuhiko; Kaku, Yasuhiko; Sakai, Noboru; Yamada, Hiromu.

    1995-01-01

    To detect cervical carotid stenosis as a candidate for carotid endarterectomy (CEA), the authors attempted a prospective trial by exploring stenosis for one year in a rural district with a population of 20,000, employing helical CT angiography which apparently displayed three-dimensional reconstructed images of the carotid bifurcation. Thirty-three patients, 24 males and 9 females, with a mean age of 71.8 years, suffering from TIA, RIND or stroke were investigated for their carotid systems. The clinical symptoms of the patients were briefly as follows: motor weakness in 30 cases, dysarthria in 8 cases and aphasia in 4 cases; and 6 of 22 (27%) stroke cases had previously suffered an episode of TIA. The risk factors of the whole group of patients were hypertension in 13 cases, diabetes mellitus in 6, heart disease in 17, and hypercholesteremia in 4. Helical CT angiography was performed in 11 cases of TIA, 2 cases of RIND, and 16 cases of stroke. Only 3 cases of the TIA group and 3 cases of the stroke group were found to have extracranial carotid stenosis of more than 50%, which subsequently required conventional angiography. For the detection of stenosis, CT angiography was beneficial as well as conventional angiography. Finally, CEA was performed in 2 of 3 cases with severe carotid stonosis in the TIA group, while such cases in the stroke group were only observed. The above results meant that the occurrence of extracranial carotid stenosis was 6 out of 6,589 elderly inhabitants (over 60 years old), although the possible detection rate of candidates for CEA was 2 out of 20,000 population per year. (author)

  14. Concordance between fine-needle aspiration and core biopsies for osseous lesions by lesion imaging appearance and CT attenuation.

    Science.gov (United States)

    Li, John; Weissberg, Zoe; Bevilacqua, Thomas A; Yu, Gordon; Weber, Kristy; Sebro, Ronnie

    2018-04-01

    To compare the concordance between fine-needle aspiration and core biopsies for osseous lesions by lesion imaging appearance and CT attenuation. Retrospective review of 215 FNAs of osseous lesions performed in conjunction with core biopsy at our institution over a 6-year period (2011-2016). FNAs were interpreted independently of core biopsies. We assessed if FNA in conjunction with core biopsy increased diagnostic accuracy compared to core biopsy alone. We also calculated the concordance between FNA and core biopsy by lesion appearance, lesion CT attenuation, lesion histology, lesion location and FNA needle gauge size. Core biopsy alone provided the diagnosis in 207/215 cases (96.3%), however, the FNA provided the diagnosis in the remaining 8/215 cases (3.7%) where the core biopsy was non-diagnostic. There were 154 (71.6%) lytic lesions, 21 (9.8%) blastic lesions, 25 (11.6%) mixed lytic and blastic lesions and 15 (7.0%) lesions that were neither lytic nor blastic. The concordance between FNA and core biopsy for lytic osseous lesions (136/154 cases, 88.3%) was statistically significantly higher than that for blastic osseous lesions (13/21 cases, 61.9%) [P = 4.2 × 10 -3 ; 95% CI (0.02, 0.50)]. The concordance between FNA and core biopsy was higher for low-attenuation- (110/126) than high-attenuation (58/77) lesions (P = 0.028). The concordance between FNA and core biopsy was also higher for metastases (102/119 cases, 85.7%) than non-metastases (78/96, 81.3%) [P = 0.487; 95% CI (- 0.15, 0.065)]. There was no difference in the rate of concordance between FNA and core biopsy by lesion location or FNA needle gauge size (P > 0.05). FNA with core biopsy increases diagnostic rate compared to core biopsy alone or FNA alone. The concordance between FNA and core biopsy is higher for lytic lesions than for blastic lesions; and higher for low-attenuation lesions than for high-attenuation lesions.

  15. Appearance and impact of post-operative intracranial clips and coils on whole-brain CT angiography and perfusion

    International Nuclear Information System (INIS)

    Roach, Cayce J.; Russell, Cheryl L.; Hanson, Eric H.; Bluett, Brent; Orrison, William W.

    2012-01-01

    Background: To evaluate the effect of vascular clips and endovascular coils placed for intracranial aneurysms and arteriovenous malformations on whole-brain computed tomography (CT) angiography and perfusion. Methods: A 320-detector row dynamic volume CT system imaged 11 patients following surgical placement of vascular clips or endovascular coils. The extent of clip and coil subtraction by automated software was evaluated using CT digital subtraction angiography and CT perfusion. Impact on CT perfusion values by retained intracranial devices was compared to age- and gender-matched controls. Results: Clip and coil subtraction on CT angiography was graded as good in 8 and moderate in 3 cases. A residual neck and additional aneurysm were noted in 1 of 11 patients. Post-procedural axial slice level CT perfusion values decreased in reliability with increasing proximity to the metallic devices secondary to beam hardening. However, the intracranial devices did not affect axial slice level CTP values of cerebral blood volume, cerebral blood flow and mean transit time outside of the level of the device. Time to peak values was globally decreased outside of the immediate vascular intervention region. Conclusions: Advances in CT technology have provided clinically useful subtraction of intracranial clips and coils. While CT perfusion values were altered in device subtraction areas and within beam hardening artifact areas; they can provide valuable postoperative information on whole-brain hemodynamics. In selected cases, the combination of CT angiography and whole-brain CT perfusion can offer an alternative to conventional angiography that is a more invasive option.

  16. Mediastinal fibrosis with pulmonary artery obstruction; diagnosis and investigation with helical CT imaging including 3-dimensional reconstructions; Pulomonalarterienstenose bei aggresiver Mediastinalfibrose; Diagnostik und 3D-Darstellung mittels helikaler CT-Untersuchung

    Energy Technology Data Exchange (ETDEWEB)

    Kolbe, M. [Inst. fuer Diagnostische Radiologie, Kantonsspital Basel (Switzerland); Helwig, A. [Inst. fuer Diagnostische Radiologie, Kantonsspital Basel (Switzerland); Habicht, J.M. [Klinik fuer Herz-Torax-Chirurgie, Universitaetskliniken Basel (Switzerland); Steinbruch, W. [Inst. fuer Diagnostische Radiologie, Kantonsspital Basel (Switzerland)

    1997-07-01

    An aggressive mediastinal fibrosis was found in a 42-year-old female, suffering from dysphagia, stabbing pain in the chest, and an unclear weight loss. In this case, the rare combination of esophageal involvement, bronchial narrowing, and pulmonary artery obstruction could easily be demonstrated with a barium study and a helical CT examination including three-dimensional reconstructions. (orig.) [Deutsch] Wir stellen den Fall einer 42jaehrigen Patientin vor, welche zur Abklaerung einer zunehmenden Dysphagie, stechender Thoraxschmerzen und eines Gewichtsverlustes hospitalisiert wurde. Mittels klinischer und radiologischer Abklaerung konnte eine aggressive Mediastinalfibrose diagnostiziert werden. Die seltene Kombination einer Oesophaguseinengung mit Pulmonalarterienstenosen sowie einer Bronchuskompression konnte nichtinvasiv mittels Oesophagogramm und helikaler CT-Untersuchung zuverlaessig und schnell dargestellt werden. (orig.)

  17. Radiation dose reduction at a price: the effectiveness of a male gonadal shield during helical CT scans

    OpenAIRE

    Erdi Yusuf E; Casciotta Kevin A; Dauer Lawrence T; Rothenberg Lawrence N

    2007-01-01

    Abstract Background It is estimated that 60 million computed tomography (CT) scans were performed during 2006, with approximately 11% of those performed on children age 0–15 years. Various types of gonadal shielding have been evaluated for reducing exposure to the gonads. The purpose of this study was to quantify the radiation dose reduction to the gonads and its effect on image quality when a wrap-around male pediatric gonad shield was used during CT scanning. This information is obtained to...

  18. Utility of Megavoltage Fan-Beam CT for Treatment Planning in a Head-And-Neck Cancer Patient with Extensive Dental Fillings Undergoing Helical Tomotherapy

    International Nuclear Information System (INIS)

    Yang, Claus; Liu Tianxiao; Jennelle, Richard L.; Ryu, Janice K.; Vijayakumar, Srinivasan; Purdy, James A.; Chen, Allen M.

    2010-01-01

    The purpose of this study was to demonstrate the potential utility of megavoltage fan-beam computed tomography (MV-FBCT) for treatment planning in a patient undergoing helical tomotherapy for nasopharyngeal carcinoma in the presence of extensive dental artifact. A 28-year-old female with locally advanced nasopharyngeal carcinoma presented for radiation therapy. Due to the extensiveness of the dental artifact present in the oral cavity kV-CT scan acquired at simulation, which made treatment planning impossible on tomotherapy planning system, MV-FBCT imaging was obtained using the HI-ART tomotherapy treatment machine, with the patient in the treatment position, and this information was registered with her original kV-CT scan for the purposes of structure delineation, dose calculation, and treatment planning. To validate the feasibility of the MV-FBCT-generated treatment plan, an electron density CT phantom (model 465, Gammex Inc., Middleton, WI) was scanned using MV-FBCT to obtain CT number to density table. Additionally, both a 'cheese' phantom (which came with the tomotherapy treatment machine) with 2 inserted ion chambers and a generic phantom called Quasar phantom (Modus Medical Devices Inc., London, ON, Canada) with one inserted chamber were used to confirm dosimetric accuracy. The MV-FBCT could be used to clearly visualize anatomy in the region of the dental artifact and provide sufficient soft-tissue contrast to assist in the delineation of normal tissue structures and fat planes. With the elimination of the dental artifact, the MV-FBCT images allowed more accurate dose calculation by the tomotherapy system. It was confirmed that the phantom material density was determined correctly by the tomotherapy MV-FBCT number to density table. The ion chamber measurements agreed with the calculations from the MV-FBCT generated phantom plan within 2%. MV-FBCT may be useful in radiation treatment planning for nasopharyngeal cancer patients in the setting of extensive

  19. Suspected ureteral colic: plain film and sonography vs unenhanced helical CT. A prospective study in 66 patients

    Energy Technology Data Exchange (ETDEWEB)

    Ripolles, Tomas; Agramunt, Marcos; Errando, Jose; Martinez, Maria Jesus [Department of Radiology, Hospital Universitario Dr. Peset, 90 Gaspar Aguilar Avenue, 46017, Valencia (Spain); Coronel, Belen [Department of Urology, Hospital Universitario Dr. Peset, 90 Gaspar Aguilar Avenue, 46017, Valencia (Spain); Morales, Maria [Research Unit, Hospital Universitario Dr. Peset, 90 Gaspar Aguilar Avenue, 46017, Valencia (Spain)

    2004-01-01

    The aim of this study was to compare the sensitivity and specificity of plain abdominal films plus ultrasound, vs nonenhanced CT for the diagnosis of ureteral colic in patients with acute flank pain. During a 4-month period, 66 patients (mean age 48 years) with acute flank pain were prospectively studied by means of plain abdominal film, US, and unenhanced CT. The presence of lithiasis and of obstructive uropathy signs were determined. The plain film was only used as a guide for the US exam. Clinical follow-up of all patients was obtained. Ureteral lithiasis was confirmed in 56 patients. The CT had a greater sensitivity (93 vs 79%) and negative predictive value (71 vs 46%) for the detection of lithiasis. The combination of lithiasis plus obstructive signs showed a sensitivity and a specificity of 100% for CT and of 100 and 90%, respectively, for US. The 11 lithiasis not detected by US were passed spontaneously (10 were <5 mm). Both techniques showed similar extraurinary pathology. Computed tomography is the most accurate technique for the detection of ureteral lithiasis; however, the combination of plain film and US is an alternative to nonenhanced CT with a lower sensitivity and radiation dose that has a good practical value. (orig.)

  20. Normal width of the anterior commissure of true vocal cord in Korea adults measured by helical CT

    International Nuclear Information System (INIS)

    Lim, Woo Young; Lim, Dong Hoon; Moon, Jang Il; Ko, Yong Seok; Byeon, Joo Nam; Oh, Jae Hee

    1998-01-01

    To evaluate the mean width of anterior commissure of true vocal cord in Korean adults by measuring its dimension on spiral CT scans. We reviewed the CT scans of 53 Korean adults(age range, 23-73years; mean age 39.2 years;M:F=3D41:12) without laryngeal disorders. Soiral CT scanning was performed around the anterior commissure with 1mm slice thickness and table incrementation for 15 seconds. The anteroposterior width of the anterior commissure was measured on CT scan where the true vocal cord and arytenoid, cricoid and thyroid cartilages were all present. We determined the mean width of the anterior commissure and whether there was a relationship between age and the width of the anterior commissure. The width of the anterior commissure was between 0.9mm and 2.3mm;mean width was 1.60±0.38mm(mean±SD). Using two SDs above the mean would have defined 2.36mm as the upper limit of normal width. Statistically, no significant correlation existed between the age and the width of the anterior commissure(p>0.05). An awareuess of the normal width range of the anterior commissure in Korean adults evaluated by spiral CT enhances the possibility of early detection of invasion of the anterior commissure by glottic cancer.=20

  1. Generation of hybrid sinograms for the recovery of kV-CT images with metal artifacts for helical tomotherapy

    International Nuclear Information System (INIS)

    Jeon, Hosang; Park, Dahl; Kim, Wontaek; Ki, Yongkan; Kim, Yong Ho; Lee, Ju Hye; Kim, Dongwon; Youn, Hanbean; Nam, Jiho; Lee, Jayoung; Kim, Ho Kyung

    2015-01-01

    Purpose: The overall goal of this study is to restore kilovoltage computed tomography (kV-CT) images which are disfigured by patients’ metal prostheses. By generating a hybrid sinogram that is a combination of kV and megavoltage (MV) projection data, the authors suggest a novel metal artifact-reduction (MAR) method that retains the image quality to match that of kV-CT and simultaneously restores the information of metal prostheses lost due to photon starvation. Methods: CT projection data contain information about attenuation coefficients and the total length of the attenuation. By normalizing raw kV projections with their own total lengths of attenuation, mean attenuation projections were obtained. In the same manner, mean density projections of MV-CT were obtained by the normalization of MV projections resulting from the forward projection of density-calibrated MV-CT images with the geometric parameters of the kV-CT device. To generate the hybrid sinogram, metal-affected signals of the kV sinogram were identified and replaced by the corresponding signals of the MV sinogram following a density calibration step with kV data. Filtered backprojection was implemented to reconstruct the hybrid CT image. To validate the authors’ approach, they simulated four different scenarios for three heads and one pelvis using metallic rod inserts within a cylindrical phantom. Five inserts describing human body elements were also included in the phantom. The authors compared the image qualities among the kV, MV, and hybrid CT images by measuring the contrast-to-noise ratio (CNR), the signal-to-noise ratio (SNR), the densities of all inserts, and the spatial resolution. In addition, the MAR performance was compared among three existing MAR methods and the authors’ hybrid method. Finally, for clinical trials, the authors produced hybrid images of three patients having dental metal prostheses to compare their MAR performances with those of the kV, MV, and three existing MAR

  2. Radiation dose reduction at a price: the effectiveness of a male gonadal shield during helical CT scans

    International Nuclear Information System (INIS)

    Dauer, Lawrence T; Casciotta, Kevin A; Erdi, Yusuf E; Rothenberg, Lawrence N

    2007-01-01

    It is estimated that 60 million computed tomography (CT) scans were performed during 2006, with approximately 11% of those performed on children age 0–15 years. Various types of gonadal shielding have been evaluated for reducing exposure to the gonads. The purpose of this study was to quantify the radiation dose reduction to the gonads and its effect on image quality when a wrap-around male pediatric gonad shield was used during CT scanning. This information is obtained to assist the attending radiologist in the decision to utilize such male gonadal shields in pediatric imaging practice. The dose reduction to the gonads was measured for both direct radiation and for indirect scattered radiation from the abdomen. A 6 cm 3 ion chamber (Model 10X5-6, Radcal Corporation, Monrovia, CA) was placed on a Humanoid real bone pelvic phantom at a position of the male gonads. When exposure measurements with shielding were made, a 1 mm lead wrap-around gonadal shield was placed around the ion chamber sensitive volume. The use of the shields reduced scatter dose to the gonads by a factor of about 2 with no appreciable loss of image quality. The shields reduced the direct beam dose by a factor of about 35 at the expense of extremely poor CT image quality due to severe streak artifacts. Images in the direct exposure case are not useful due to these severe artifacts and the difficulties in positioning these shields on patients in the scatter exposure case may not be warranted by the small absolute reduction in scatter dose unless it is expected that the patient will be subjected to numerous future CT scans

  3. Radiation dose reduction at a price: the effectiveness of a male gonadal shield during helical CT scans.

    Science.gov (United States)

    Dauer, Lawrence T; Casciotta, Kevin A; Erdi, Yusuf E; Rothenberg, Lawrence N

    2007-03-16

    It is estimated that 60 million computed tomography (CT) scans were performed during 2006, with approximately 11% of those performed on children age 0-15 years. Various types of gonadal shielding have been evaluated for reducing exposure to the gonads. The purpose of this study was to quantify the radiation dose reduction to the gonads and its effect on image quality when a wrap-around male pediatric gonad shield was used during CT scanning. This information is obtained to assist the attending radiologist in the decision to utilize such male gonadal shields in pediatric imaging practice. The dose reduction to the gonads was measured for both direct radiation and for indirect scattered radiation from the abdomen. A 6 cm3 ion chamber (Model 10X5-6, Radcal Corporation, Monrovia, CA) was placed on a Humanoid real bone pelvic phantom at a position of the male gonads. When exposure measurements with shielding were made, a 1 mm lead wrap-around gonadal shield was placed around the ion chamber sensitive volume. The use of the shields reduced scatter dose to the gonads by a factor of about 2 with no appreciable loss of image quality. The shields reduced the direct beam dose by a factor of about 35 at the expense of extremely poor CT image quality due to severe streak artifacts. Images in the direct exposure case are not useful due to these severe artifacts and the difficulties in positioning these shields on patients in the scatter exposure case may not be warranted by the small absolute reduction in scatter dose unless it is expected that the patient will be subjected to numerous future CT scans.

  4. Radiation dose reduction at a price: the effectiveness of a male gonadal shield during helical CT scans

    Directory of Open Access Journals (Sweden)

    Erdi Yusuf E

    2007-03-01

    Full Text Available Abstract Background It is estimated that 60 million computed tomography (CT scans were performed during 2006, with approximately 11% of those performed on children age 0–15 years. Various types of gonadal shielding have been evaluated for reducing exposure to the gonads. The purpose of this study was to quantify the radiation dose reduction to the gonads and its effect on image quality when a wrap-around male pediatric gonad shield was used during CT scanning. This information is obtained to assist the attending radiologist in the decision to utilize such male gonadal shields in pediatric imaging practice. Methods The dose reduction to the gonads was measured for both direct radiation and for indirect scattered radiation from the abdomen. A 6 cm3 ion chamber (Model 10X5-6, Radcal Corporation, Monrovia, CA was placed on a Humanoid real bone pelvic phantom at a position of the male gonads. When exposure measurements with shielding were made, a 1 mm lead wrap-around gonadal shield was placed around the ion chamber sensitive volume. Results The use of the shields reduced scatter dose to the gonads by a factor of about 2 with no appreciable loss of image quality. The shields reduced the direct beam dose by a factor of about 35 at the expense of extremely poor CT image quality due to severe streak artifacts. Conclusion Images in the direct exposure case are not useful due to these severe artifacts and the difficulties in positioning these shields on patients in the scatter exposure case may not be warranted by the small absolute reduction in scatter dose unless it is expected that the patient will be subjected to numerous future CT scans.

  5. MR appearance of cartilage defects of the knee: preliminary results of a spiral CT arthrography-guided analysis

    International Nuclear Information System (INIS)

    Berg, B.C. vande; Lecouvet, F.E.; Maldague, B.; Malghem, J.

    2004-01-01

    The aim of this study was to determine signal intensity patterns of cartilage defects at MR imaging. The MR imaging (3-mm-thick fat-suppressed intermediate-weighted fast spin-echo images) was obtained in 31 knees (21 male and 10 female patients; mean age 45.5 years) blindly selected from a series of 252 consecutive knees investigated by dual-detector spiral CT arthrography. Two radiologists determined in consensus the MR signal intensity of the cartilage areas where cartilage defects had been demonstrated on the corresponding reformatted CT arthrographic images. There were 83 cartilage defects at spiral CT arthrography. In 52 (63%) lesion areas, the MR signal intensity was higher than that of adjacent normal cartilage with signal intensity equivalent to (n=31) or lower than (n=21) that of articular fluid. The MR signal intensity was equivalent to that of adjacent normal cartilage in 17 (20%) lesion areas and lower than that of adjacent cartilage in 8 (10%) lesion areas. In 6 (7%) lesion areas, mixed low and high signal intensity was observed. The MR signal intensity of cartilage defects demonstrated on spiral CT arthrographic images varies from low to high on fat-suppressed intermediate-weighted fast spin-echo MR images obtained with our equipment and MR parameters. (orig.)

  6. Acute pulmonary embolism in helical computed tomography

    International Nuclear Information System (INIS)

    Paslawski, M.

    2005-01-01

    Pulmonary embolism is a common condition in which diagnostic and therapeutic delays contribute to substantial morbidity and mortality. Clinical diagnosis is difficult because the signs and symptoms re unspecific, and a differential diagnosis is extensive, including pneumonia or bronchitis, asthma, myocardial infraction, pulmonary edema, anxiety, dissection of the aorta, pericardial tamponade, lung cancer, primary pulmonary hypertension, rib fracture, and pneumothorax. The purpose of the study was to present the use of CT in diagnosing acute pulmonary embolism. A group of 23 patients with clinically suspected pulmonary embolism underwent CT examination with a helical CT scanner (Somatom Emotion, Siemens) before and after administration of 150 ml of Ultravist. Pulmonary embolism was found in the CT examinations of 13 patients. In two of these it was a central filling defect. Amputation of the artery was found in one. Parietal filling defect in three patients formed an acute angle with the vessel walls. Saddle emboli appearing as filling defects in the contrast column that hung over vessel bifurcations was found in two patients. In five patients,emboli were found in small segmental arteries. CT provides information not only on the pulmonary arteries, but also on the lung parenchyma, hila, mediastinum, and the heart. Alternative findings may be identified by CT chest examination, stablishing alternative diagnoses, including pulmonary disorders (such as pneumonia or fibrosis), pleural abnormalities, and cardiovascular disease (such as aortic dissection or pericardial tamponade). Another advantage of the CT is its widespread availability.(author)

  7. An evaluation of the regional cerebral blood flow (rCBF) measurement by xenon-enhanced dynamic CT with helical scanning technique and the functional imaging by multiplanar reconstruction (MPR). Fundamental study and clinical application

    International Nuclear Information System (INIS)

    Watanabe, Kenichi

    1997-01-01

    We evaluated the quantitative rCBF by xenon-enhanced dynamic CT with helical scanning technique on all brain regions, and also examined clinical usefulness of coronal and sagittal section images which are similar to SPECT images obtained by the functional multiplanar reconstitution (MPR) imaging of many successive flow maps. We used 14 clinical cases. The conventional xenon-enhanced CT was simple and ideal method to measure rCBF, however, it had disadvantages; it gives a few laminagraphical images or only the axial directional images, compared to SPECT or PET. There is a risk to overlook lesions out of the image or not to obtain the whole images of the lesion. Although the helical scanning technique has a methodological characteristics to use adjacent data for the image reconstitution, it is by no means inferior to the conventional method in the contrast resolution or the image resolution when the co-helical function and an appropriate reconstituted function were used. It has an advantage to scan all brain regions by only one cycle of scanning. Furthermore on making good use of the property that the helical scanning technique can give the successive data, we can observe rCBF by coronal and sagittal images when many flow maps were made up by reconstituted images of the narrow steps. This shows the clinical usefulness of this technique. One of the future problem to be solved is to decrease the exposure dose. (K.H.)

  8. Metastatic squamous cell carcinoma of the gingiva appearing as a solitary branchial cyst carcinoma: diagnostic role of PET/CT.

    Science.gov (United States)

    Zhang, Xiong-Xin; Zhao, Kui; Zhou, Shui-Hong; Wang, Qin-Ying; Liu, Jian-Hua; Lu, Zhong-Jie

    2014-01-01

    We herein present a case of a left cervical cystic mass, for which the initial pathological diagnosis was branchial cleft cyst carcinoma (following complete mass excision). Thorough postoperative examinations, including with FDG positron emission tomography/computed tomography (PET/CT), revealed a primary tumor in the retromolar region of the left mandible. A 52-year-old female presented with a 2-month history of a painless, progressively enlarged left-sided neck mass. Fine-needle aspiration biopsy suggested a branchial cleft cyst. Physical examination revealed a 3 × 3-cm smooth, tender mass in the upper-left neck and anterior border of the sternocleidomastoid muscle. Examination using nasendoscopy and a strobolaryngoscope revealed no abnormalities of the nasal cavity, nasopharynx, oropharynx, hypopharynx or larynx. MRI of the neck revealed a solitary, round, cystic mass under the left parotid gland. The mass was excised completely. Pathologic results indicated a branchial cleft cyst carcinoma. According to the diagnostic criteria for a branchial cleft cystic carcinoma, PET/CT was performed to detect the occult primary site. PET/CT revealed high FDG uptake in the tooth root of the left mandible. Frozen sections of the mass were indicative of moderate, differentiated squamous cell carcinoma. The carcinoma in the retromolar region of the left mandible was locally excised under general anesthesia. A partial left maxillectomy, partial mandibulectomy, and left radical neck dissection were performed. The patient received postoperative concurrent chemoradiotherapy, and was disease-free at the 8-month follow-up. True branchial cleft cyst carcinoma is rare: once diagnosed, it should be distinguished from metastatic cystic cervical lymph and occult primary carcinoma. FDG PET/CT is useful in the identification of occult primary tumor.

  9. Well-differentiated liposarcoma of the retroperitoneum with a fat-fluid level: US, CT, and MR appearance

    Energy Technology Data Exchange (ETDEWEB)

    Kurosaki, Y.; Tanaka, Y.O.; Itai, Y. [Department of Radiology, University of Tsukuba, Tsukuba-shi (Japan)

    1998-03-27

    We report a case of retroperitoneal liposarcoma with a fat-fluid level that has not been previously described. A 36-year-old man presented with abdominal distension. Ultrasonography, CT, and MR imaging showed a tumor with a fat-fluid level; nondependent fluid was characteristic of fat. Liposarcoma should be included in the differential diagnosis of tumors exhibiting a fat-fluid level. (orig.) With 1 fig., 11 refs.

  10. Well-differentiated liposarcoma of the retroperitoneum with a fat-fluid level: US, CT, and MR appearance

    International Nuclear Information System (INIS)

    Kurosaki, Y.; Tanaka, Y.O.; Itai, Y.

    1998-01-01

    We report a case of retroperitoneal liposarcoma with a fat-fluid level that has not been previously described. A 36-year-old man presented with abdominal distension. Ultrasonography, CT, and MR imaging showed a tumor with a fat-fluid level; nondependent fluid was characteristic of fat. Liposarcoma should be included in the differential diagnosis of tumors exhibiting a fat-fluid level. (orig.)

  11. Deep learning of the sectional appearances of 3D CT images for anatomical structure segmentation based on an FCN voting method.

    Science.gov (United States)

    Zhou, Xiangrong; Takayama, Ryosuke; Wang, Song; Hara, Takeshi; Fujita, Hiroshi

    2017-10-01

    issue of anatomical structure segmentation in 3D CT cases. The novelty of this work is the policy of deep learning of the different 2D sectional appearances of 3D anatomical structures for CT cases and the majority voting of the 3D segmentation results from multiple crossed 2D sections to achieve availability and reliability with better efficiency, generality, and flexibility than conventional segmentation methods, which must be guided by human expertise. © 2017 The Authors. Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.

  12. Analysis of main influence factors on coronary artery image quality with 64-multidetector row helical CT using a pulsating cardiac phantom

    International Nuclear Information System (INIS)

    Liu Bin; Zhao Hong; Wu Xingwang; Zhang Jiawen; Yu Yongqiang; Liao Jingmin

    2006-01-01

    Objective: To explore the main influence factors (heart rate, rotation speed, and reconstruction algorithm) on the image quality of coronary artery with 40 mm VCT (64-detector row helical CT) using a pulsating cardiac phantom. Methods: An adjustable pulsating cardiac phantom (GE) containing predetermined simulated coronary arteries was scanned using a 40 mm VCT (GE LightSpeed CT) with cardiac pulsating rates of 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, and 115 beats per minute (bpm). The variable rotation speeds technique of 0.35 s, 0.40 s, and 0.45 s were used, respectively. The raw data were reconstructed using both one-sector and multi-sector reconstruction algorithm at optimal window of the R-R interval. The image quality score (IQS) was evaluated by two radiologists according to the same evaluation standard of reformated image. The correlation between heart rate (HR), roation speed, reconstruction algorithm, and IQS were analyzed. The IQS as independent variable and the HR, rotation speed, reconstruction algorithm as dependent variables were analyzed by multiple linear regression analysis. Results: The heart rate and the reconstruction algorithm had significant influence on IQS. The rotation speed (0.35s, 0.40 s, and 0.45 s) didn't have significant influence on IQS. There was linear regression relationship between heart rate, reconstruction algorithm and IQS (P<0.01). The equation of multiple regression was IQS=5.154-0.046 x (HR) + 0.500 x (reconstruction algorithm). The multi-sector reconstruction algorithm improved the image quality than one-sector did. Conclusion: The main influence factors on the image quality of coronary artery can be evaluated with 40 mm VCT using a pulsating cardiac phantom. It plays an important role in clinical research and application. (authors)

  13. Hepatic and vascular enhancement at dual-phase helical CT: comparison of Iobitridol 300 and Iohexol 300 in a prospective randomized study

    International Nuclear Information System (INIS)

    Legmann, P.; Vignaux, O.; Bahurel, H.; Oudjit, A.; Coste, J.

    2001-01-01

    The purpose of this study was to determine hepatic and vascular enhancement, clinical tolerance, and iconographic quality of Iobitridol (300 mg/ml) at dual-phase helical CT and to compare it with Iohexol (300 mg/ml). One hundred forty-six patients were randomly divided into two groups. Each group received 120 ml of Iohexol (group A) or Iobitridol (group B). Mean enhancement of liver, aorta and portal vein was obtained at the arterial phase and at the portal-venous phase. Overall image quality was assessed by two independent blinded investigators. Adverse reactions were recorded. There were no significant differences in demographic characteristics and distribution of patient intrinsic parameters between the two groups, except for blood pressure but without statistical correlation between the difference in blood pressure and the impact on enhancement measurements. There was no significant difference in clinical tolerance and image quality. Mean liver as well as aortic and portal vein enhancement measurements did not show any significant difference. Iobitridol compares favorably with Iohexol. Both products have similar safety, tolerance, and efficacy. Both contrast media have equivalent blood pool concentration and interstitial compartment diffusion. (orig.)

  14. Hepatic and vascular enhancement at dual-phase helical CT: comparison of Iobitridol 300 and Iohexol 300 in a prospective randomized study

    Energy Technology Data Exchange (ETDEWEB)

    Legmann, P.; Vignaux, O.; Bahurel, H.; Oudjit, A. [Dept. of Radiology, Universite Rene Descartes, Paris (France); Coste, J. [Dept. of Biostatistics and Epidemiology, Universite Rene Descartes, Paris (France)

    2001-11-01

    The purpose of this study was to determine hepatic and vascular enhancement, clinical tolerance, and iconographic quality of Iobitridol (300 mg/ml) at dual-phase helical CT and to compare it with Iohexol (300 mg/ml). One hundred forty-six patients were randomly divided into two groups. Each group received 120 ml of Iohexol (group A) or Iobitridol (group B). Mean enhancement of liver, aorta and portal vein was obtained at the arterial phase and at the portal-venous phase. Overall image quality was assessed by two independent blinded investigators. Adverse reactions were recorded. There were no significant differences in demographic characteristics and distribution of patient intrinsic parameters between the two groups, except for blood pressure but without statistical correlation between the difference in blood pressure and the impact on enhancement measurements. There was no significant difference in clinical tolerance and image quality. Mean liver as well as aortic and portal vein enhancement measurements did not show any significant difference. Iobitridol compares favorably with Iohexol. Both products have similar safety, tolerance, and efficacy. Both contrast media have equivalent blood pool concentration and interstitial compartment diffusion. (orig.)

  15. Low-dose ECG-gated 64-slices helical CT angiography of the chest: evaluation of image quality in 105 patients

    International Nuclear Information System (INIS)

    D'Agostino, A.G.; Remy-Jardin, M.; Khalil, C.; Remy, J.; Delannoy-Deken, V.; Duhamel, A.; Flohr, T.

    2006-01-01

    The purpose of this study was to evaluate image quality of low-dose electrocardiogram (ECG)-gated multislice helical computed tomography (CT) angiograms of the chest. One hundred and five consecutive patients with a regular sinus rhythm (72 men; 33 women) underwent ECG-gated CT angiographic examination of the chest without administration of beta blockers using the following parameters: (a) collimation 32 x 0.6 mm with z-flying focal spot for the acquisition of 64 overlapping 0.6-mm slices, rotation time 0.33 s, pitch 0.3; (b) 120 kV, 200 mAs; (c) use of two dose modulation systems, including adjustment of the mAs setting to the patient's size and anatomical shape and an ECG-controlled tube current. Subjective and objective image quality was evaluated by two radiologists in consensus on 3-mm-thick scans reconstructed at 55% of the response rate (RR) interval. The population and protocol characteristics included: (a) a mean [±standard deviation (SD)] body mass index (BMI) of 24.47 (±4.64); (b) a mean (±SD) heart rate of 72.04 (±15.76) bpm; (c) a mean (±SD) scanning time of 18.3 (±2.73) s; (d) a mean (±SD) dose-length product (DLP) value of 260.57 (±83.67) mGy/cm; (e) an estimated average effective dose of 4.95 (±1.59) mSv. Subjective noise was depicted in a total of nine examinations (8.5%), always rated as mild. Objective noise was assessed by measuring the standard deviation of pixel values in a homogeneous region of interest within the trachea and descending aorta; SD was 15.91 HU in the trachea and 22.16 HU in the descending aorta, with no significant difference in the mean value of the standard deviations between the four categories of BMI except for obese patients, who had a higher mean SD within the aorta. Interpolation artefacts were depicted in 22 patients, with a mean heart rate significantly lower than that of patients without interpolation artifacts, rated as mild in 11 patients and severe in 11 patients. The severity of interpolation artefacts

  16. Preliminary evaluation of lung care software of 16-slice helical CT in the study of pulmonary nodules

    International Nuclear Information System (INIS)

    Song Wei; Jin Zhengyu; Yan Hongzhen; Wang Yun; Zhang Yunqing; Wang Linhui; Zhu Haifeng; Liang Jixiang; Qi Bing

    2005-01-01

    Objective: To evaluate the auxiliary diagnostic ability and applicability of the Lung Care software for the study of the pulmonary nodules. Methods: Fifty-six patients underwent low-dose CT scan with 1.5 mm collimation, 4 mm reconstruction interval, and 4 mm reconstruction slice in group A, and with 1.5 mm collimation, 2 mm reconstruction interval, and 2 mm reconstruction slice in group B. 12 patients underwent low-dose CT with 0.75 mm collimation, 0.75 mm reconstruction interval, and 0.75 mm reconstruction slice in group C. The nodules detected in groups A, B, and C were analyzed by r-MPR or VOI of the Lung Care software to distinguish the true pulmonary nodules from the vessels. The volume and density distribution of the true pulmonary nodules in groups A, B, and C were measured with the Lung Care software. Results: It was difficult to observe the diffuse pulmonary nodules by r-MPR or VOI of the Lung Care software. The images of each patient in group C were too many to be applied in the clinic. There was statistically consistent in the observation of pulmonary nodules between r-MPR and VOI, but the coincidence was not good (Kappa=0.369, P=0.002). There was statistically significant difference in showing faint nodules between r-MPR and VOI (P=0.001), r-MPR was better than VOI. There was statistically significant difference between group A and B in showing = 3.886, P=0.045), but no statistically significant difference in showing 5-10 mm nodules (χ 2 =0.170, P=0.680). The volume and density distribution of most 5 - ≤20 mm nodules were successfully measured with the Lung Care software, whereas those of most 2 =5.811, P=0.016) and 5-10 mm nodules (χ 2 =13.500, P 10 - ≤20 mm nodules (χ 2 =0.000, P=1.000). Conclusion: For distinguishing the true pulmonary nodules from others, the Lung Care software is suitable for the well-edged pulmonary nodules and most faint nodules, but not suitable for the nodules such as ground-glass opacity. For measuring the volume and

  17. Primary chylous vaginal discharge in a 9-year-old girl: CT-lymphangiogram and MR appearance

    International Nuclear Information System (INIS)

    Shahlaee, A.H.; Burton, E.M.; Sabio, H.; Plouffe, L. Jr.; Teeslink, R.

    1997-01-01

    Chylous reflux is a manifestation of primary or secondary lymphatic obstruction. Primary lymphatic obstruction is defined as lymphangiectasia and incompetency of lymphatic valves without an underlying cause. Lymphangiectasia resulting from trauma, neoplasm, irradiation, or inflammation characterizes secondary lymphatic obstruction. Leakage of chyle into the uterus, vagina, bladder, or rectum can occur with either primary or secondary lymphatic obstruction. We report a patient with chylous vaginal discharge, a rare presentation of primary chylous reflux syndrome. CT-lymphangiography and magnetic resonance imaging clearly depicted this disorder. To our knowledge, only 20 cases of chylous vaginal discharge have been reported previously; chylous vaginal drainage occurred in the absence of chylous uterine reflux in only three. Although this is a rare anomaly, chylous reflux should be considered in a child with chronic vaginal discharge and lower extremity swelling. (orig.). With 3 figs

  18. Primary chylous vaginal discharge in a 9-year-old girl: CT-lymphangiogram and MR appearance.

    Science.gov (United States)

    Shahlaee, A H; Burton, E M; Sabio, H; Plouffe, L; Teeslink, R

    1997-09-01

    Chylous reflux is a manifestation of primary or secondary lymphatic obstruction. Primary lymphatic obstruction is defined as lymphangiectasia and incompetency of lymphatic valves without an underlying cause. Lymphangiectasia resulting from trauma, neoplasm, irradiation, or inflammation characterizes secondary lymphatic obstruction. Leakage of chyle into the uterus, vagina, bladder, or rectum can occur with either primary or secondary lymphatic obstruction. We report a patient with chylous vaginal discharge, a rare presentation of primary chylous reflux syndrome. CT-lymphangiography and magnetic resonance imaging clearly depicted this disorder. To our knowledge, only 20 cases of chylous vaginal discharge have been reported previously; chylous vaginal drainage occurred in the absence of chylous uterine reflux in only three. Although this is a rare anomaly, chylous reflux should be considered in a child with chronic vaginal discharge and lower extremity swelling.

  19. Complete opacification of the esophageal lumen using helical (slip-ring) CT scanner with cellulose-barium paste, and its application to the evaluation of the effect of radiation therapy for esophageal cancer

    International Nuclear Information System (INIS)

    Noda, Yoshihiro; Ogawa, Yasuhiro; Nishioka, Akihito; Inomata, Taisuke; Yoshida, Shoji; Toki, Taiichi; Ogoshi, Shohei

    1996-01-01

    The esophageal lumen of patients with esophageal cancer or paraesophageal disorders is frequently impossible to visualize on CT image and, consequently, difficulties in the differentiation of esophageal tumor mass and adjacent organs are often encountered. Therefore, we have developed a safe, high viscous, oral contrast medium which contains carboxy-methyl cellulose sodium (a conventionally used laxative with mild effect and inexpensive) and low-density 2% barium. Helical CT scan using this medium plus intravenous injection of iodine contrast enhancement agent was performed in 24 patients with esophageal cancer or paraesophageal diseases. Complete opacification of the esophageal lumen was obtained for almost all images of the upper, middle and lower thoracic esophagus. This method is easy to use and has not caused any serious side effect so far. We have developed a new oral contrast agent for esophageal helical CT to estimate the volume of tumor on CT images before and after treatment. The therapeutic effect of radiotherapy in 10 patients with esophageal cancer was evaluated using this method. In seven of the 10 patients, the rate of decrease of the esophageal tumor mass during radiotherapy was much lower with our new method than with conventionally used method. Combination of these two methods is essential for the evaluation of the therapeutic effect of radiotherapy for esophageal cancer. (author)

  20. 4D-CT scans reveal reduced magnitude of respiratory liver motion achieved by different abdominal compression plate positions in patients with intrahepatic tumors undergoing helical tomotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Yong, E-mail: hu.yong@zs-hospital.sh.cn; Zhou, Yong-Kang, E-mail: zhouyk2009@163.com; Chen, Yi-Xing, E-mail: chen.yixing@zs-hospital.sh.cn; Shi, Shi-Ming, E-mail: shiming32@126.com; Zeng, Zhao-Chong, E-mail: zeng.zhaochong@zs-hospital.sh.cn [Department of Radiation Oncology, Zhongshan Hospital, Fudan University, 180 Feng Lin Road, Shanghai 200032 (China)

    2016-07-15

    Purpose: While abdominal compression (AC) can be used to reduce respiratory liver motion in patients receiving helical tomotherapy for hepatocellular carcinoma, the nature and extent of this effect is not well described. The purpose of this study was to evaluate the changes in magnitude of three-dimensional liver motion with abdominal compression using four-dimensional (4D) computed tomography (CT) images of several plate positions. Methods: From January 2012 to October 2015, 72 patients with intrahepatic carcinoma and divided into four groups underwent 4D-CT scans to assess respiratory liver motion. Of the 72 patients, 19 underwent abdominal compression of the cephalic area between the subxiphoid and umbilicus (group A), 16 underwent abdominal compression of the caudal region between the subxiphoid area and the umbilicus (group B), 11 patients underwent abdominal compression of the caudal umbilicus (group C), and 26 patients remained free breathing (group D). 4D-CT images were sorted into ten-image series, according to the respiratory phase from the end inspiration to the end expiration, and then transferred to treatment planning software. All liver contours were drawn by a single physician and confirmed by a second physician. Liver relative coordinates were automatically generated to calculate the liver respiratory motion in different axial directions to compile the 10 ten contours into a single composite image. Differences in respiratory liver motion were assessed with a one-way analysis of variance test of significance. Results: The average respiratory liver motion in the Y axial direction was 4.53 ± 1.16, 7.56 ± 1.30, 9.95 ± 2.32, and 9.53 ± 2.62 mm in groups A, B, C, and D, respectively, with a significant change among the four groups (p < 0.001). Abdominal compression was most effective in group A (compression plate on the subxiphoid area), with liver displacement being 2.53 ± 0.93, 4.53 ± 1.16, and 2.14 ± 0.92 mm on the X-, Y-, and Z

  1. CT appearance of mesenteric saponification.

    Science.gov (United States)

    Paris, A; Willing, S J

    1991-01-01

    Although saponification of the pancreas is a frequent finding on computed tomography, saponification of extrapancreatic mesenteric sites has not been previously recognized. A case is presented of acute pancreatitis in which serial scans over a four-year period documented calcifications in old extrapancreatic phlegmons. Saponification from pancreatitis should be considered in the differential diagnosis of mesenteric calcifications.

  2. 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.

  3. Helical Confinement Concepts

    Energy Technology Data Exchange (ETDEWEB)

    Beidler, C; Brakel, R; Burhenn, R; Dinklage, A; Erckmann, V; Feng, Y; Geiger, J; Hartmann, D; Hirsch, M; Jaenicke, R; Koenig, R; Laqua, H P; Maassberg, H; Wagner, F; Weller, A; Wobig, H [Max-Planck Institut fuer Plasmaphysik, EURATOM Association, Greifswald (Germany)

    2012-09-15

    Stellarators, conceived 1951 by Lyman Spitzer in Princeton, are toroidal devices that confine a plasma in a magnetic field which originates from currents in coils outside the plasma. A plasma current driven by external means, for example by an ohmic transformer, is not required for confinement. Supplying the desired poloidal field component by external coils leads to a helically structured plasma topology. Thus stellarators - or helical confinement devices - are fully three-dimensional in contrast to the toroidal (rotational) symmetry of tokamaks. As stellarators can be free of an inductive current, whose radial distribution depends on the plasma parameters, their equilibrium must not be established via the evolving plasma itself, but to a first order already given by the vacuum magnetic field. They do not need an active control (like positional feedback) and therefore cannot suffer from its failure. The outstanding conceptual advantage of stellarators is the potential of steady state plasma operation without current drive. As there is no need for current drive, the recirculating power is expected to be smaller than in equivalent tokamaks. The lack of a net current avoids current driven instabilities; specifically, no disruptions, no resistive wall modes and no conventional or neoclassical tearing modes appear. Second order pressure-driven currents (Pfirsch-Schlueter, bootstrap) exist but they can be modified and even minimized by the magnetic design. The magnetic configuration of helical devices naturally possesses a separatrix, which allows the implementation of a helically structured divertor for exhaust and impurity control. (author)

  4. Significance of diagnosis of liver metastases from colorectal cancer by angio helical CT and intermittent hepatic arterial infusion chemotherapy after hepatic resection in terms of prognosis

    International Nuclear Information System (INIS)

    Hatsuse, Kazuo; Aoki, Hideki; Murayama, Michinori

    1997-01-01

    Seventy five cases had undergone hepatic resection for liver metastases from colorectal cancer from 1979 to 1994. Computed tomography during hepatic angiography (angio CT) was tried in 27 cases. At first, we compared detection ratios of angio CT for liver metastase to those of ultrasonography, conventional CT, and operative ultrasonography on these 27 cases. Next, the prognosis of seventy five cases was examined. They were divided into three groups; the HX group 29 cases with only hepatic resection; the HX+AP group of 19 cases with intermittent hepatic arterial infusion chemotherapy after hepatic resection; the angio CT group of 27 cases selected for hepatic resection by angio CT, followed by the same infusion chemotherapy as that given to the HX+AP group. Fifty metastases were diagnosed histopathologically in twenty seven cases that underwent hepatic resection after angio CT. Detection ratios for small metastases 1.0 cm or smaller in diameter were 8.3% with ultrasonography, 25% with CT, 75% with angio CT, and 50% with operative ultrasonography. Detection ratios of angio CT were superior to those of ultrasonography and CT. Recurrence rates of the remnant liver were significantly low and survival rates were significantly superior in the angio CT group compared to the other two groups (p<0.02). The prognosis with and without intermittent hepatic arterial infusion chemotherapy after hepatic resection were significantly different (p<0.03). The above data suggest that improvement of detection ratios for liver metastases by angio CT, and probably concomitant intermittent hepatic infusion chemotherapy contribute to decreased remnant liver recurrence and an increased survival rate. (author)

  5. 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.

  6. Closed laryngeal trauma by hanging. CT appearance, one case; Traumatisme ferme du larynx par pendaison. Aspect scanographique a propos d`un cas

    Energy Technology Data Exchange (ETDEWEB)

    Poquet, E.; Dibiane, A.; Jourdain, C.; El-Amine, M.; Jacob, A.; Escure, M.N. [Centre Hospitalier, 91 - Corbeil-Essonnes (France)

    1995-02-01

    The closed laryngeal traumas by attempt of hanging are rarely studied by medical imaging. The lesions are evaluated by fiberoptic endoscopy and CT scan. We report a case of complicated lesions of the larynx with rupture of the cricothyroid membrane, diagnosed by CT scan and we discuss the usefulness to this technique. (authors). 7 refs., 3 figs.

  7. Percutaneous radiofrequency thermal ablation of lung VX2 tumors in a rabbit model: evaluation with helical CT findings for the complete and partal ablation

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Gong Yong; Han, Young Min; Lim, Yeong Su; Jang, Kyu Yun; Lee, Sang Yong; Chung, Gyung Ho [School of Medicine, Chonbuk National Univ., Chonju (Korea, Republic of)

    2004-05-01

    To evaluate the radiologic findings for complete and partial ablation after percutaneous CT-guided transthoracic radiofrequency ablation (RFA) of lung VX2 tumor implanted in rabbits. Thirteen rabbits with successfully implanted lung VX2 were used. Three rabbits as controls did not receive RFA while the other ten rabbits underwent RFA; 5 complete and 5 partial. RFA was performed using an internally cooled, 17-gauge electrode (Radionics, Burlington, MA) with a 1-cm active tip under CT guidance. Postprocedural CT was performed within 3 days, and we analyzed the ablated size, enhancement pattern, shape, margin, and complications of the complete and partial ablation groups. Rabbits were sacrificed after postprocedural CT with an overdose of ketamine, and pathologic findings of the ablated groups were compared with those of the control group. The size of the ablated lesions and the enhancement pattern differed between the completely and partially ablated groups on chest CT. The size of the ablated lesions was increased by 47.1% in the completely ablated group and by 2.1% in the partially ablated group. In the completely ablated group, VX2 tumor showed absolutely no enhancement, whereas only ablated pulmonary parenchyma outside VX2 showed mild enhancement on enhanced CT. In the partial ablated group, a part of VX2 became strongly enhanced on enhanced CT. On microscopic examination, the completely ablated group demonstrated that a viable tumor cell was not visible. In the partially ablated group, however, a viable tumor cell within the surrounding fibrous capsule on the peripheral area of the VX2 was observed. The important CT findings for evaluation of complete and partial RFA are the ablated size and enhancement pattern of the ablated lesion.

  8. Detection of hepatocellular carcinoma by Gd-EOB-DTPA-enhanced liver MRI: Comparison with triple phase 64 detector row helical CT

    International Nuclear Information System (INIS)

    Akai, Hiroyuki; Kiryu, Shigeru; Matsuda, Izuru; Satou, Jirou; Takao, Hidemasa; Tajima, Taku; Watanabe, Yasushi; Imamura, Hiroshi; Kokudo, Norihiro; Akahane, Masaaki; Ohtomo, Kuni

    2011-01-01

    Purpose: To compare the diagnostic performance of Gd-EOB-DTPA-enhanced MRI with that of triple phase 64-MDCT in the detection of hepatocellular carcinoma (HCC). Patients and methods: Thirty-four patients with 52 surgically proven lesions underwent Gd-EOB-DTPA-enhanced MRI and triple phase 64-MDCT. Two observers independently evaluated MR and CT imaging on a lesion-by-lesion basis. Sensitivity, positive and negative predictive values and reproducibility were evaluated. The diagnostic accuracy of each modality was assessed with alternative-free response receiver operating characteristic (ROC) analysis. Results: Both observers showed higher sensitivity in detecting lesions with MRI compared to CT, however, only the difference between the two imaging techniques for observer 2 was significant (P = 0.034). For lesions 1 cm or smaller, MRI and CT showed equal sensitivity (both 62.5%) with one observer, and MRI proved superior to CT with the other observer (MRI 75% vs. CT 56.3%), but the latter difference was not significant (P = 0.083). The difference in positive and negative predictive value between the two imaging techniques for each observer was not significant (P > 0.05). The areas under the ROC curve for each observer were 0.843 and 0.861 for MRI vs. 0.800 and 0.833 for CT and the differences were not significant. Reproducibility was higher using MRI for both observers, but the result was not significant (MRI 32/33 vs. CT 29/33, P = 0.083). Conclusion: Gd-EOB-DTPA-enhanced MRI tended to show higher diagnostic accuracy, sensitivity and reproducibility compared to triple phase 64-MDCT in the detection of hepatocellular carcinoma, however statistical significance was not achieved.

  9. CT appearance of radiation injury of the lung and clinical symptoms after stereotactic body radiation therapy (SBRT) for lung cancers: Are patients with pulmonary emphysema also candidates for SBRT for lung cancers?

    International Nuclear Information System (INIS)

    Kimura, Tomoki; Matsuura, Kanji; Murakami, Yuji; Hashimoto, Yasutoshi; Kenjo, Masahiro; Kaneyasu, Yuko; Wadasaki, Koichi; Hirokawa, Yutaka; Ito, Katsuhide; Okawa, Motoomi

    2006-01-01

    Purpose: The purpose of this study was to analyze the computed tomographic (CT) appearance of radiation injury to the lung and clinical symptoms after stereotactic body radiation therapy (SBRT) and evaluate the difference by the presence of pulmonary emphysema (PE) for small lung cancers. Methods and Materials: In this analysis, 45 patients with 52 primary or metastatic lung cancers were enrolled. We evaluated the CT appearance of acute radiation pneumonitis (within 6 months) and radiation fibrosis (after 6 months) after SBRT. Clinical symptoms were evaluated by Common Terminology Criteria for Adverse Events, version 3.0. We also evaluated the relationship between CT appearance, clinical symptoms, and PE. Results: CT appearance of acute radiation pneumonitis was classified as follows: (1) diffuse consolidation, 38.5%; (2) patchy consolidation and ground-glass opacities (GGO), 15.4%; (3) diffuse GGO, 11.5%; (4) patchy GGO, 2.0%; (5) no evidence of increasing density, 32.6%. CT appearance of radiation fibrosis was classified as follows: (1) modified conventional pattern, 61.5%; (2) mass-like pattern, 17.3%; (3) scar-like pattern, 21.2%. Patients who were diagnosed with more than Grade 2 pneumonitis showed significantly less no evidence of increased density pattern and scar-like pattern than any other pattern (p = 0.0314, 0.0297, respectively). Significantly, most of these patients with no evidence of increased density pattern and scar-like pattern had PE (p = 0.00038, 0.00044, respectively). Conclusion: Computed tomographic appearance after SBRT was classified into five patterns of acute radiation pneumonitis and three patterns of radiation fibrosis. Our results suggest that SBRT can be also safely performed even in patients with PE

  10. The helical tomotherapy thread effect

    International Nuclear Information System (INIS)

    Kissick, M.W.; Fenwick, J.; James, J.A.; Jeraj, R.; Kapatoes, J.M.; Keller, H.; Mackie, T.R.; Olivera, G.; Soisson, E.T.

    2005-01-01

    Inherent to helical tomotherapy is a dose variation pattern that manifests as a 'ripple' (peak-to-trough relative to the average). This ripple is the result of helical beam junctioning, completely unique to helical tomotherapy. Pitch is defined as in helical CT, the couch travel distance for a complete gantry rotation relative to the axial beam width at the axis of rotation. Without scattering or beam divergence, an analytical posing of the problem as a simple integral predicts minima near a pitch of 1/n where n is an integer. A convolution-superposition dose calculator (TomoTherapy, Inc.) included all the physics needed to explore the ripple magnitude versus pitch and beam width. The results of the dose calculator and some benchmark measurements demonstrate that the ripple has sharp minima near p=0.86(1/n). The 0.86 factor is empirical and caused by a beam junctioning of the off-axis dose profiles which differ from the axial profiles as well as a long scatter tail of the profiles at depth. For very strong intensity modulation, the 0.86 factor may vary. The authors propose choosing particular minima pitches or using a second delivery that starts 180 deg off-phase from the first to reduce these ripples: 'Double threading'. For current typical pitches and beam widths, however, this effect is small and not clinically important for most situations. Certain extremely large field or high pitch cases, however, may benefit from mitigation of this effect

  11. Diagnosis of acute flank pain caused by ureteral stones: value of combined direct and indirect signs on IVU and unenhanced helical CT

    International Nuclear Information System (INIS)

    Wang, Li-Jen; Wong, Yon-Cheong; Ng, Chip-Jin; Chen, Jih-Chang; Chiu, Te-Fa

    2004-01-01

    The aim of this study was to assess the usefulness of combined direct and indirect signs on intravenous urography (IVU) and unenhanced helical computed tomography (UHCT) for the diagnosis of ureteral stones in emergency patients with acute flank pain. During an 8-month period, 82 emergency patients with acute flank pain undergoing IVU and UHCT with sufficient clinical follow-up formed the study group. The presence or absence of direct sign (visualization of ureteral stones) and indirect signs on IVU and UHCT was recorded. The diagnostic accuracy of each direct/indirect sign and their combination for the diagnosis of ureteral stones on IVU and UHCT were analyzed and compared. Of the 82 patients, 66 had ureteral stones, four had passed urinary stones prior to imaging and 12 had other diseases. The diagnostic accuracies of direct signs on IVU and UHCT for the diagnosis of ureteral stones were 79.3 and 98.8%, respectively, which was more accurate than that of any single indirect sign on IVU and UHCT. However, the diagnostic accuracy of ureteral stones by IVU increased to 90.2% when using diagnostic criteria requiring the presence of a direct sign or at least three indirect signs, and by UHCT, it increased to 100% when using diagnostic criteria requiring the presence of a direct sign with at least one indirect sign. Therefore, for emergency patients with acute flank pain, the use of the above combinations of direct/indirect signs is useful as the diagnostic criterion for ureteral stones. (orig.)

  12. Comparision between biphasic helical CT and dynamic gadolinium-enhanced MR in the detection and characterization of focal hepatic lesions in cirrhotic patients

    International Nuclear Information System (INIS)

    Puig, J.; Martin, J.; Donoso, L.; Falco, J.; Rue, M.

    1997-01-01

    To assess the agreement between biphasic helical computerized tomography (BHCT) and dynamic gadolinium-enhanced magnetic resonance (MR) in the detection and characterization of focal hepatic lesions in a group of cirrhotic patients. A prospective study was done in 50 cirrhotic patients suspected of having hepatocarcinoma (HC) on the basis of ultrasonographic images evaluated by means of BHCT and dynamic gadolinium-enhanced MR using fast low-angle shot (FLASH) sequences (110-135/4/90 degree centigree). The images were assessed jointly by four radiologists. Between the two techniques, a total of 83 lesions were detected. MR disclosed more lesions (n=79) than BHCT (n=67) (p<0.005). Moreover, 25 of the lesions that were visible by both techniques were more clearly evident in MR images (p<0.01). MR correctly classified 6 of 7 benign lesions (85%) and 49 of 66 malignant ones (74%). BHCT correctly classifed 2 of 7 benign lesions (28%) and 32 of 66 malignant ones (48%). The sensitivities of MR and BHCT for the characterization of these lesions were 74% and 48%, respectively (p=0.0009), while the respective specificities were 86% and 29% (P<0.001). Dynamic gadolinium-enhanced MR with FLASH sequences is more efficient than BHCT in the detection and characterization of focal lesions in cirrhotic patients. (Author) 37 refs

  13. The CT appearances of delayed amniotic fluid clearance from the lungs in an infant with absent pulmonary valve and congenital lobar emphysema

    International Nuclear Information System (INIS)

    Fink, A. Michelle; Edis, Brian; Massie, John

    2005-01-01

    Congenital lobar emphysema (CLE) is a cause of severe neonatal respiratory distress. Overexpansion of the affected pulmonary lobe in the fetus is due to narrowing of the airway, with a resultant 'ball-valve' effect. At birth, there may be delayed clearance of fetal lung fluid. Early chest radiographs show opacification of the hyperexpanded lobe. The CT findings in the immediate neonatal period have not been previously reported. We describe the imaging in a neonate with tetralogy of Fallot and absent pulmonary valve with secondary CLE. CT demonstrates the hyperexpanded lobe with initial thickening of the interlobular septa and alveolar ground glass attenuation, with subsequent clearing. This resorption of fetal lung fluid via the pulmonary interstitium should not be confused with interstitial lung disease. (orig.)

  14. The CT appearances of delayed amniotic fluid clearance from the lungs in an infant with absent pulmonary valve and congenital lobar emphysema

    Energy Technology Data Exchange (ETDEWEB)

    Fink, A. Michelle [Royal Children' s Hospital, Department of Medical Imaging, Parkville, Victoria (Australia); University of Melbourne, Melbourne, Victoria (Australia); Edis, Brian [Royal Children' s Hospital, Department of Cardiology, Parkville, Victoria (Australia); Massie, John [University of Melbourne, Melbourne, Victoria (Australia); Royal Children' s Hospital, Department of Respiratory Medicine, Parkville, Victoria (Australia); Murdoch Children' s Research Institute, Melbourne, Victoria (Australia)

    2005-09-01

    Congenital lobar emphysema (CLE) is a cause of severe neonatal respiratory distress. Overexpansion of the affected pulmonary lobe in the fetus is due to narrowing of the airway, with a resultant 'ball-valve' effect. At birth, there may be delayed clearance of fetal lung fluid. Early chest radiographs show opacification of the hyperexpanded lobe. The CT findings in the immediate neonatal period have not been previously reported. We describe the imaging in a neonate with tetralogy of Fallot and absent pulmonary valve with secondary CLE. CT demonstrates the hyperexpanded lobe with initial thickening of the interlobular septa and alveolar ground glass attenuation, with subsequent clearing. This resorption of fetal lung fluid via the pulmonary interstitium should not be confused with interstitial lung disease. (orig.)

  15. Helicity content and tokamak applications of helicity

    International Nuclear Information System (INIS)

    Boozer, A.H.

    1986-05-01

    Magnetic helicity is approximately conserved by the turbulence associated with resistive instabilities of plasmas. To generalize the application of the concept of helicity, the helicity content of an arbitrary bounded region of space will be defined. The definition has the virtues that both the helicity content and its time derivative have simple expressions in terms of the poloidal and toroidal magnetic fluxes, the average toroidal loop voltage and the electric potential on the bounding surface, and the volume integral of E-B. The application of the helicity concept to tokamak plasmas is illustrated by a discussion of so-called MHD current drive, an example of a stable tokamak q profile with q less than one in the center, and a discussion of the possibility of a natural steady-state tokamak due to the bootstrap current coupling to tearing instabilities

  16. The role of 3D Helical CT in the reconstructive treatment of maxillofacial cancers; Tomografia Computerizzata spirale con elaborazioni tridimensionali di superficie nel trattamento ricostruttivo dei tumori maligni del massiccio facciale

    Energy Technology Data Exchange (ETDEWEB)

    De Rosa, V.; Ziviello, M. [Ospedale Cardarelli, Servizio di Radiodiagnostica, Naples (Italy); Ionna, F.; Mozzillo, N. [Ospedale Cardarelli, Div. di Chirurgia B, Ist. Nazionale Tumori Fondazione G. Pascale, Naples (Italy); Parascandolo, S. [Ospedale Cardarelli, Div. di Chirurgia Maxillo-Facciale, Naples (Italy)

    2000-12-01

    Purpose of this work is to investigate the role of Helical CT and the usefulness of three-dimensional (3D) imaging for pre-operative planning and follow-up of reconstructive maxillofacial surgery with alloplastic material in neoplastic disease involving this region. From 1996 to 1999 eleven patients were examined with Helical CT and 3D images for planning of maxillofacial plastic and reconstructive surgery for advanced cancer of this anatomically complex region. A 3D-modulated titanium mesh (100%) or micronets was used to rebuild the anterior surface of maxillary bone and the orbital floor. The mesh was cut to the appropriate size and shape and curved where necessary. Within the residual sinusal cavity a siliconed filling was used surmounting an acrylic prosthesis with dental arch to rebuild the palate. A rehydrated bovine pericardium was affixed and moduled on the borders in two cases only. Three-dimensionally reconstructed CT images were obtained preoperatively and at least 6 months postoperatively in all patients. The images were generated on a computer workstation using the shaded surface display (SSD) software with threshold values ranging 425 to 630 HU, and a more closed window for the imaging of titanium mesh/bone interface in the post surgical follow-up. It was obtained an excellent complete spatial depiction of maxillo facial region both before and after surgery, with no artefacts so important as to affect the 3D reconstruction process and the image quality. Together with the head-neck surgical team it could be worked for preoperative planning through CT scans by different 3D points of view. The 3D reconstructed follow-up scans showed good filling of the defect in the area where the titanium mesh had been used. Then efficacious bone modelling and good biocompatibility of the alloplastic material were seen in all patients, with no inflammatory reactions. Titanium is a well-known material, which is widely used for cranioplasty. It is a radiolucent, non

  17. Intravenous digital subtraction angiography and helical computed tomography in evaluation of living renal donors

    International Nuclear Information System (INIS)

    Watarai, Yoshihiko; Usuki, Tomoaki; Takeuchi, Ichiro; Nonomura, Katsuya; Koyanagi, Tomohiko; Kubo, Kozo; Hirano, Tetsuo; Togashi, Masaki; Ohashi, Nobuo

    2001-01-01

    The present study was carried out to evaluate the accuracy of helical computed tomography (CT) and intravenous digital subtraction angiography (IV-DSA) on anatomical assessment of renal vasculature for living renal donors. Forty-two healthy potential renal donors were prospectively evaluated and 35 subsequently underwent donor nephrectomy after helical CT and IV-DSA evaluation. The vascular and non-vascular findings were compared between the findings on helical CT, IV-DSA and surgery. Ten prehilar branches and five accessory renal arteries were found at nephrectomy. Overall, operative findings agreed with the findings by IV-DSA in 89% and by helical CT in 83%. In delineating accessory arteries, IV-DSA had a sensitivity of 60% and specificity of 97%, whereas helical CT had a sensitivity of 40% and specificity of 100%. In delineating prehilar branches, IV-DSA had a sensitivity of 90% and specificity of 100%, whereas helical CT had a sensitivity of 70% and specificity of 100%. Accessory arteries and prehilar branches that were not detected by helical CT or IV-DSA, were less than 2 mm in diameter and did not require vascular reconstruction. Renal veins were delineated in 63% by IV-DSA, whereas they were clearly imaged by helical CT in all cases, including a case with a circumaortic renal vein. Non-vascular findings were obtained in 64% by helical CT, including two renal tumors. None of these findings were obtained by IV-DSA. Helical CT and IV-DSA provide comparably sufficient information on renal artery vasculature. However, helical CT provides significantly more information on venous and non-vascular findings as a single-imaging modality. (author)

  18. Individualized radiation dose control in 256-slice CT coronary angiography (CTCA) in retrospective ECG-triggered helical scans: Using a measure of body size to adjust tube current selection

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jing-Lei, E-mail: lijinglei80@126.com [Department of Radiology, Guangdong Academy of Medical Sciences, Guangdong General Hospital, 106 Zhongshan Er Road, Guangzhou 510080 (China); Huang, Mei-Ping, E-mail: huang_meiping@yahoo.com.cn [Department of Radiology, Guangdong Academy of Medical Sciences, Guangdong General Hospital, 106 Zhongshan Er Road, Guangzhou 510080 (China); Liang, Chang-Hong, E-mail: cjr.lchh@vip.163.com [Department of Radiology, Guangdong Academy of Medical Sciences, Guangdong General Hospital, 106 Zhongshan Er Road, Guangzhou 510080 (China); Zhao, Zhen-Jun, E-mail: junabc2006@hotmail.com [Department of Radiology, Guangdong Academy of Medical Sciences, Guangdong General Hospital, 106 Zhongshan Er Road, Guangzhou 510080 (China); Liu, Hui, E-mail: liuhuijiujiu@gmail.com [Department of Radiology, Guangdong Academy of Medical Sciences, Guangdong General Hospital, 106 Zhongshan Er Road, Guangzhou 510080 (China); Cui, Yan-Hai, E-mail: yanhai_cui@126.com [Department of Radiology, Guangdong Academy of Medical Sciences, Guangdong General Hospital, 106 Zhongshan Er Road, Guangzhou 510080 (China); Liu, Qi-Shun, E-mail: liuqishun@yeah.net [Department of Radiology, Guangdong Academy of Medical Sciences, Guangdong General Hospital, 106 Zhongshan Er Road, Guangzhou 510080 (China); Zhang, Jin-E., E-mail: zhjine@yahoo.com.cn [Department of Radiology, Guangdong Academy of Medical Sciences, Guangdong General Hospital, 106 Zhongshan Er Road, Guangzhou 510080 (China); Yang, Lin, E-mail: yanglin001517@163.com [Department of Radiology, Guangdong Academy of Medical Sciences, Guangdong General Hospital, 106 Zhongshan Er Road, Guangzhou 510080 (China); Ivanc, Thomas B., E-mail: Thomas.ivanc@philips.com [CT Clinical Science, Philips Healthcare, Highland Heights, OH (United States); Yanof, Jeffrey H., E-mail: Jeffrey.yanof@philips.com [CT Clinical Science, Philips Healthcare, Highland Heights, OH (United States)

    2012-11-15

    Purpose: To reduce radiation dose for retrospective ECG-triggered helical 256-slice CTCA by determining an optimal body size index to prospectively adjust tube current. Methods: 102 consecutive patients with suspected CAD underwent retrospective ECG-triggered CTCA using 256-slice CT scanner. Six body size indexes including BMI, nipple level (NL) bust, thoracic anteroposterior diameter at NL, chest circumference (CC) at NL, left main and right coronary artery (RCA) origin level were measured and their correlation with noise was evaluated using linear regression. An equation was developed to use this index to adjust tube current. Additional 102 consecutive patients were scanned with the index-based mA s adjustment. A t-test for independent samples was used to compare radiation dose levels with and without the index-based mA s selection method. Results: Linear regression indicated that CC RCA had the best correlation with noise (R{sup 2} = 0.603). Effective radiation dose was reduced from 16.6 {+-} 0.9 to 9.8 {+-} 2.7 mSv (p < 0.01), i.e. 40.9% lower dose with the CC RCA-adapted tube current method. The image quality scores indicated no significant difference with and without the size-based mA s selection method. Conclusion: An accessible measure of body size, such as CC RCA, can be used to adapt tube current for individualized radiation dose control.

  19. Individualized radiation dose control in 256-slice CT coronary angiography (CTCA) in retrospective ECG-triggered helical scans: Using a measure of body size to adjust tube current selection

    International Nuclear Information System (INIS)

    Li, Jing-Lei; Huang, Mei-Ping; Liang, Chang-Hong; Zhao, Zhen-Jun; Liu, Hui; Cui, Yan-Hai; Liu, Qi-Shun; Zhang, Jin-E.; Yang, Lin; Ivanc, Thomas B.; Yanof, Jeffrey H.

    2012-01-01

    Purpose: To reduce radiation dose for retrospective ECG-triggered helical 256-slice CTCA by determining an optimal body size index to prospectively adjust tube current. Methods: 102 consecutive patients with suspected CAD underwent retrospective ECG-triggered CTCA using 256-slice CT scanner. Six body size indexes including BMI, nipple level (NL) bust, thoracic anteroposterior diameter at NL, chest circumference (CC) at NL, left main and right coronary artery (RCA) origin level were measured and their correlation with noise was evaluated using linear regression. An equation was developed to use this index to adjust tube current. Additional 102 consecutive patients were scanned with the index-based mA s adjustment. A t-test for independent samples was used to compare radiation dose levels with and without the index-based mA s selection method. Results: Linear regression indicated that CC RCA had the best correlation with noise (R 2 = 0.603). Effective radiation dose was reduced from 16.6 ± 0.9 to 9.8 ± 2.7 mSv (p < 0.01), i.e. 40.9% lower dose with the CC RCA-adapted tube current method. The image quality scores indicated no significant difference with and without the size-based mA s selection method. Conclusion: An accessible measure of body size, such as CC RCA, can be used to adapt tube current for individualized radiation dose control.

  20. The usefulness of contrast material injection at the dorsal vein of the hand in 64-detecter row helical CT coronary angiography

    International Nuclear Information System (INIS)

    Kawano, Youji; Yakabe, Kazuaki; Urata, Jungo; Eto, Miyuki; Yamaguchi, Hiroichiro

    2011-01-01

    In 315 cases of multi detector row CT (MDCT) coronary angiography contrast material were injected at the dorsal vein of the hand. Early 168 cases were used 80 ml of 370 mgI/ml contrast material and later 147 cases were used 350-480 mgI/kg contrast material. In all cases contrast material was injected by 4 ml/sec with post injection of 30-40 ml physiologic saline. The attenuation of RCA No.3 and other coronary arteries or coronary artery bypass graft (CABG) graft was measured. In later cases the usefulness of above 300 HU was 95.2%. In all cases the usefulness was 92.6%. (author)

  1. CT of tracheal agenesis

    International Nuclear Information System (INIS)

    Strouse, Peter J.; Hernandez, Ramiro J.; Newman, Beverley

    2006-01-01

    Tracheal agenesis is a rare and usually lethal anomaly. In the past, opaque contrast medium was injected via the esophagus to demonstrate the anatomy. To demonstrate the utility of helical and multidetector CT in delineating the aberrant anatomy in newborns with tracheal agenesis. Four newborns with tracheal agenesis were identified from three institutions. Imaging studies and medical records were reviewed. Each child was imaged with chest radiography. One child was imaged on a single-detector helical CT scanner and the other three on multidetector scanners. Helical and multidetector CT with 2D and 3D reconstructions clearly delineated the aberrant tracheobronchial and esophageal anatomy in each infant. Minimum intensity projection reformatted CT images were particularly helpful. One infant each had type I and type II tracheal agenesis. Two infants had type III tracheal agenesis. All four infants died. CT is a useful tool for delineating the aberrant anatomy of newborns with tracheal agenesis and thus helps in making rational clinical decisions. (orig.)

  2. Helical type vacuum container

    International Nuclear Information System (INIS)

    Owada, Kimio.

    1989-01-01

    Helical type vacuum containers in the prior art lack in considerations for thermal expansion stresses to helical coils, and there is a possibility of coil ruptures. The object of the present invention is to avoid the rupture of helical coils wound around the outer surface of a vacuum container against heat expansion if any. That is, bellows or heat expansion absorbing means are disposed to a cross section of a helical type vacuum container. With such a constitution, thermal expansion of helical coils per se due to temperature elevation of the coils during electric supply can be absorbed by expansion of the bellows or absorption of the heat expansion absorbing means. Further, this can be attained by arranging shear pins in the direction perpendicular to the bellows axis so that the bellows are not distorted when the helical coils are wound around the helical type vacuum container. (I.S.)

  3. Prospective ECG-triggered axial CT at 140-kV tube voltage improves coronary in-stent restenosis visibility at a lower radiation dose compared with conventional retrospective ECG-gated helical CT

    Energy Technology Data Exchange (ETDEWEB)

    Horiguchi, Jun; Fujioka, Chikako; Kiguchi, Masao; Kohno, Shingo [Hiroshima University Hospital, Department of Clinical Radiology, Hiroshima (Japan); Yamamoto, Hideya; Kitagawa, Toshiro [Hiroshima University, Department of Molecular and Internal Medicine, Division of Clinical Medical Science, Programs for Applied Biomedicine, Graduate School of Biomedical Sciences, Hiroshima (Japan); Ito, Katsuhide [Hiroshima University, Department of Radiology, Division of Medical Intelligence and Informatics, Programs for Applied Biomedicine, Graduate School of Biomedical Sciences, Hiroshima (Japan)

    2009-10-15

    The purpose of this study was to compare coronary 64-slice CT angiography (CTA) protocols, specifically prospective electrocardiograph (ECG)-triggered and retrospective ECG-gated CT acquisition performed using a tube voltage of 140 kV and 120 kV, regarding intracoronary stent imaging. Coronary artery stents (n=12) with artificial in-stent restenosis (50% luminal reduction, 40 HU) on a cardiac phantom were examined by CT at heart rates of 50-75 beats per minute (bpm). The subjective visibility of in-stent restenosis was evaluated with a three-point scale (1 clearly visible, 2 visible, and 3 not visible), and artificial lumen narrowing [(inner stent diameter - measured lumen diameter)/inner stent diameter], lumen attenuation increase ratio [(in-stent attenuation - coronary lumen attenuation)/coronary lumen attenuation], and signal-to-noise ratio of in-stent lumen were determined. The effective dose was estimated. The artificial lumen narrowing (mean 43%), the increase of lumen attenuation (mean 46%), and signal-to-noise ratio (mean 7.8) were not different between CT acquisitions (p=0.12-0.91). However, the visibility scores of in-stent restenosis were different (p<0.05) between ECG-gated CTA techniques: (a) 140-kV prospective (effective dose 4.6 mSv), 1.6; (b) 120-kV prospective (3.3 mSv), 1.8; (c) 140-kV retrospective (16.4-18.8 mSv), 1.9; and (d) 120-kV retrospective (11.0-13.4 mSv), 1.9. Thus, 140-kV prospective ECG-triggered CTA improves coronary in-stent restenosis visibility at a lower radiation dose compared with retrospective ECG-gated CTA. (orig.)

  4. Multiple helical modes of vortex breakdown

    DEFF Research Database (Denmark)

    Sørensen, Jens Nørkær; Naumov, I. V.; Okulov, Valery

    2011-01-01

    Experimental observations of vortex breakdown in a rotating lid-driven cavity are presented. The results show that vortex breakdown for cavities with high aspect ratios is associated with the appearance of stable helical vortex multiplets. By using results from stability theory generalizing Kelvi......’s problem on vortex polygon stability, and systematically exploring the cavity flow, we succeeded in identifying two new stable vortex breakdown states consisting of triple and quadruple helical multiplets....

  5. [Comparison of radiation dose reduction of prospective ECG-gated one beat scan using 320 area detector CT coronary angiography and prospective ECG-gated helical scan with high helical pitch (FlashScan) using 64 multidetector-row CT coronary angiography].

    Science.gov (United States)

    Matsutani, Hideyuki; Sano, Tomonari; Kondo, Takeshi; Fujimoto, Shinichiro; Sekine, Takako; Arai, Takehiro; Morita, Hitomi; Takase, Shinichi

    2010-12-20

    A high radiation dose associated with 64 multidetector-row computed tomography (64-MDCT) is a major concern for physicians and patients alike. A new 320 row area detector computed tomography (ADCT) can obtain a view of the entire heart with one rotation (0.35 s) without requiring the helical method. As such, ADCT is expected to reduce the radiation dose. We studied image quality and radiation dose of ADCT compared to that of 64-MDCT in patients with a low heart rate (HR≤60). Three hundred eighty-five consecutive patients underwent 64-MDCT and 379 patients, ADCT. Patients with an arrhythmia were excluded. Prospective ECG-gated helical scan with high HP (FlashScan) in 64 was used for MDCT and prospective ECG-gated conventional one beat scan, for 320-ADCT. Image quality was visually evaluated by an image quality score. Radiation dose was estimated by DLP (mGy・cm) for 64-MDCT and DLP.e (mGy・cm) for 320-ADCT. Radiation dose of 320-ADCT (208±48 mGy・cm) was significantly (P<0.0001) lower than that of 64-MDCT (484±112 mGy・cm), and image quality score of 320-ADCT (3.0±0.2) was significantly (P=0.0011) higher than that of 64-MDCT (2.9±0.4). Scan time of 320-ADCT (1.4±0.1 s) was also significantly (P<0.0001) shorter than that of 64-MDCT (6.8±0.6 s). 320-ADCT can achieve not only a reduction in radiation dose but also a superior image quality and shortening of scan time compared to 64-MDCT.

  6. Evidence for Mixed Helicity in Erupting Filaments

    Science.gov (United States)

    Muglach, K.; Wang, Y.-M.; Kliem, B.

    2009-09-01

    Erupting filaments are sometimes observed to undergo a rotation about the vertical direction as they rise. This rotation of the filament axis is generally interpreted as a conversion of twist into writhe in a kink-unstable magnetic flux rope. Consistent with this interpretation, the rotation is usually found to be clockwise (as viewed from above) if the post-eruption arcade has right-handed helicity, but counterclockwise if it has left-handed helicity. Here, we describe two non-active-region filament events recorded with the Extreme-Ultraviolet Imaging Telescope on the Solar and Heliospheric Observatory in which the sense of rotation appears to be opposite to that expected from the helicity of the post-event arcade. Based on these observations, we suggest that the rotation of the filament axis is, in general, determined by the net helicity of the erupting system, and that the axially aligned core of the filament can have the opposite helicity sign to the surrounding field. In most cases, the surrounding field provides the main contribution to the net helicity. In the events reported here, however, the helicity associated with the filament "barbs" is opposite in sign to and dominates that of the overlying arcade.

  7. Dose reduction in coronary artery imaging with 64-row multi-slice helical CT with body mass index-dependent mA selection

    International Nuclear Information System (INIS)

    Gao Jianhua; Wang Guisheng; Zheng Jingchen; Li Jianying; Sun Xianchang; Gao Caihong; Dai Ruping

    2008-01-01

    Objective: To evaluate the robustness of body mass index (BMI) adapted tube current selection method for obtaining consistent image quality in MSCT coronary artery imaging. Methods: Initially one hundred patients in the control group (C group) underwent cardiac scans using GE 64-row VCT with standard scan protocol (640 mA, 120 kV, 0.35 sec, body bowtie, C 2 filter). Noise measurement was obtained for each patient using the average of three consecutive slices in the ascending aorta with ROI of 10 mm x 10 mm to establish the relationship between BMI, desired image noise (IN) and required mA. An excel table was established to predict the required mA to achieve a desired IN for each patient with different BMI. A second group of one hundred cardiac patients (L group) was scanned with BMI-adapted mA from the table to evaluate the practicability of this method. BMI, IN, CT dose index (CTDI), effective dose (ED) were all recorded. Results: For the control group of 100 patients, the mean values and standard deviations of image quality score (IQS), BMI, IN and ED were 3.71±0.54, 25.08±2.63, 24.56±5.03 and (17.63±1.68) mSv (with range of 15-22 mSv). Regression analysis indicated linear relationship between BMI and image noise with fixed mA. Using the relationship between tube current and image noise and noise ratio between large bowtie and cardiac bowtie, the following equation for the required tube current Xma to achieve present image noise of INa for patient with certain BMI value when using cardiac bowtie could be then obtained: Xma=Fma x [(k 1 x BMI + c 1 )/Ina] 2 , where Fma=640 mA, k 1 =1.033, c 1 = -3.2, INa=27 in the study. (2) For the patients in L group, the mean values and standard deviations of IQS, BMI, and IN were 3.69±0.53, 25.07±2.91, and 26.61±3.44, respectively. The average tube current used was (469.95±113.45) mA, depending on patient's BMI values. The average effectively dose was (9.08±2.25) mSv. There was no statistically difference between the

  8. Helicity and Filament Channels? The Straight Twist!

    Science.gov (United States)

    Antiochos, Spiro K.

    2010-01-01

    One of the most important and most puzzling features of the coronal magnetic field is that it appears to have smooth magnetic structure with little evidence for non-potentiality except at special locations, photospheric polarity inversions lines where the non-potentiality is observed as a filament channel. This characteristic feature of the closed-field corona is highly unexpected given that photospheric motions continuously tangle its magnetic field. Although reconnection can eliminate some of the injected structure, it cannot destroy the helicity, which should build up to produce observable complexity. We propose that an inverse cascade process transports the injected helicity from the interior of closed flux regions to their boundaries, polarity inversion lines, creating filament channels. We describe how the helicity is injected and transported and calculate the relevant rates. We argue that one process, helicity transport, can explain both the observed lack and presence of structure in the coronal magnetic field.

  9. Hereditary haemorrhagic telangiectasia: study of hepatic vascular alterations with multi-detector row helical CT and reconstruction programs; Telangiectasia emorragica ereditaria: TC multidetettore multifasica e programmi di ricostruzione nello studio delle alterazioni vascolari epatiche

    Energy Technology Data Exchange (ETDEWEB)

    Memeo, Maurizio; Stabile Ianora, Amato Antonio; Scaldapane, Arnaldo; Rotondo, Antonio; Angelelli, Giuseppe [Policlinico Universitario, Bari (Italy). DiMIMP Sezione di Diagnostica per Immagini; Suppressa, Patrizia; Cirulli, Anna; Sabba' , Carlo [Policlinico Universitario, Bari (Italy). Centro Interdipartimentale per lo studio dell' HHT

    2005-02-01

    Purpose: To evaluate hepatic alterations in patients affected by Hereditary Haemorrhagic Telangiectasia (HHT) by using multidetector row helical CT (MDCT) and new reconstruction programs. Materials and methods: An MDCT multiphasic study of the liver was performed in 105 consecutive patients: 89 considered to be affected by HHT and 16 with suspicion of disease alone. The scan delay was determined by using a test bolus of contrast material. The CT examination was performed with a triphasic technique (double arterial phase and portal venous phase). multiplanar and angiographic reconstructions were then obtained, and the images checked for the presence of shunts, hepatic perfusion disorders, vascular lesions (telangiectasis and large confluent vascular masses), indirect signs of portal hypertension, and anatomical vascular variants. Results: Hepatic vascular alterations were found in 78/105 cases (67/89) patients affected by HHT and 11/16 patients with clinical suspicion alone). Therefore HHT diagnosis was excluded in 5 patients. 78/100 (78%) patients with HHT had intrahepatic vascular alterations: arterioportal shunts in 40/78 (51.2%) arteriosystemic shunts in 16/78 (20.5%) and both shunt types in 22/78 (28.3%). Intraparenchymal perfusion disorders were found in 46/78 (58.9%) patients. Telangiectasis were recognised in 50/78 (64.1%) patients. Large confluent vascular masses (LCVMs) were identified in 20/78 (25.6%) patients. indirect signs of portal hypertension were found in 46/78 (58.9%) cases. Variant hepatic arterial anatomy was present in 38/100 cases (38%). Conclusions: Multiphasic MDCT and the new reconstruction programs enable the identification and characterisation of the complex vascular alterations typical of HHT. [Italian] Scopo: Valutare le alterazioni epatiche nei pazienti affetti da Telangiectasia Emorraica Ereditaria (TEE) utilizzando una TC multidetettore (TCMD) ed in nuovi programmi di ricostruzione. Materiale e metodi: E' stato eseguito uno

  10. A note on helicity

    International Nuclear Information System (INIS)

    Bialynicki-Birula, I.; Newmann, E.T.; Porter, J.; Winicour, J.; Lukacs, B.; Perjes, Z.; Sebestyen, A.

    1981-03-01

    The authors give a formal definition of the helicity operator for integral spin fields, which does not involve their momentum-space decomposition. The discussion is based upon a representation of the Pauli-Lubanski operator in terms of the action on tensor fields by the Killing vectors associated with the generators of the Poincare group. This leads to an identification of the helicity operator with the duality operator defined by the space-time alternating tensor. Helicity eigenstates then correspond to self-dual or anti-self-dual fields, in agreement with usage implicit in the literature. In addiition, the relationship between helicity eigenstates which are intrinsically non-classical, and states of right or left circular polarization in classical electrodynamics are discussed. (author)

  11. 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

  12. Nonideal, helical, vortical magnetohydrodynamic steady states

    International Nuclear Information System (INIS)

    Agim, Y.Z.; Montgomery, D.

    1991-01-01

    The helically-deformed profiles of driven, dissipative magnetohydrodynamic equilibria are constructed through second order in helical amplitude. The resultant plasma configurations are presented in terms of contour plots of magnetic flux function, pressure, current flux function and the mass flux function, along with the stability boundary at which they are expected to appear. For the Wisconsin Phaedrus-T Tokamak, plasma profiles with significant m = 3, n = 1 perturbation seem feasible; for these, the plasma pressure peaks off-axis. For the smaller aspect ratio case, the configuration with m 1,n =1 is thought to be relevant to the density perturbation observed in JET after a pellet injection. (author)

  13. Imaging appearances of cholesterol pneumonia

    International Nuclear Information System (INIS)

    Miao Yanwei; Zhang Jingwen; Wu Jianlin; Zhou Yong; Li Mingwu; Lei Zhen; Shi Lifu

    2006-01-01

    Objection: To analyze the imaging appearances of cholesterol pneumonia. Methods We retrospectively analyzed the X-ray and CT findings of 3 patients with cholesterol pneumonia confirmed pathologically and reviewed correlative literature. Results: Lesions similar to mass were found in X-ray and CT imaging of three cases. Two of them appeared cavity with fluid-level and one showed multiple ring enhancement after CT contrast. The course of disease was very. long and it had no respond to antibiotic therapy. Amounts of foam cells rich in cholesterol crystal were detected in pathological examination. Conclusions: Cholesterol pneumonia is a rare chronic pulmonary idiopathic disease, and the radiological findings can do some help to its diagnosis. (authors)

  14. Helicity, Reconnection, and Dynamo Effects

    International Nuclear Information System (INIS)

    Ji, Hantao

    1998-01-01

    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

  15. Multiphasic helical Computed Tomography of hepatocellular carcinoma. Evaluation after various percutaneous ablation procedures

    International Nuclear Information System (INIS)

    Catalano, O.; Esposito, M.; Lobianco, R.; Cusati, B.; Altei, F.; Siani, A.

    1999-01-01

    The purpose of this paper is to report the personal experience with helical CT evaluation of hepatocellular carcinoma treated with various percutaneous interventional procedures. From December 1996 to September 1998 it were examined with helical CT 41 patients (73 nodules in all) with hepatocellular carcinoma treated with percutaneous ablation therapies: conventional ethanol injection in 18 subjects (31 nodules), one-shot ethanol injection 3 (8 nodules), radiofrequency thermal ablation in 16 (25 nodules), and combined chemo embolization and ethanol injection in 4 (9 nodules). CT performed was 4-27 days after the last session, acquiring biphasic volumetric images in 14 patients and triphasic volumetric images in 27. A second treatment with subsequent CT study was performed for 28 lesions; 15 underwent 3 serial studies and 6 underwent 4 studies. Compared with pretreatment findings, the diameter was unchanged in 62% of the nodules and increased in 38%. Morphology was unchanged in 63% of the lesions while in 37% a mild deformation toward the needle path or a more regular and round shape was evident. Borders were unchanged in 37% of the cases and modified in 63%, appearing well-defined in 73% and ill-defined in 27%. The necrotic portion had a low attenuation with a nodule-to-parenchyma gradient more evident on delayed than on venous and finally arterial acquisitions; 8% of the lesions were not recognizable on unenhanced scans. During the arterial phase the residual tumor appeared hyperdense in 97% of the nodules and isodense in 3%, while during the portal phase it was hyperdense in 22%, isodense in 28% and hypodense in 50%, and during the delayed phase hypodense in 100%. Residual viable tissue was identified in 44% of the nodules and quantified as 100% in 1% of all lesions, > 75% in 3%, > 50% in 4%, > 25% in 23%. In conclusion, multiple-phase helical CT allows optimal depiction of primitive liver nodules treated with percutaneous interventional procedures and has a

  16. Helical-D pinch

    International Nuclear Information System (INIS)

    Schaffer, M.J.

    1997-08-01

    A stabilized pinch configuration is described, consisting of a D-shaped plasma cross section wrapped tightly around a guiding axis. The open-quotes helical-Dclose quotes geometry produces a very large axial (toroidal) transform of magnetic line direction that reverses the pitch of the magnetic lines without the need of azimuthal (poloidal) plasma current. Thus, there is no need of a open-quotes dynamoclose quotes process and its associated fluctuations. The resulting configuration has the high magnetic shear and pitch reversal of the reversed field pinch (RFP). (Pitch = P = qR, where R = major radius). A helical-D pinch might demonstrate good confinement at q << 1

  17. The appearance of foramen in the internal aspect of the mental region of mandible from japanese cadavers and dry skulls under macroscopic observation and three-dimensional CT images

    International Nuclear Information System (INIS)

    Yoshida, Shunji; Kawai, Taisuke; Okutsu, Koichiro; Yosue, Takashi; Sunohara, Masataka; Sato, Iwao; Takamori, Hitoshi

    2005-01-01

    The lingual canal with foramen displays different appearances on the internal surfaces of mandible as confirmed by macroscopic observation and computerized tomography (CT). The lingual canal was observed in the inside of mental region run to the outside of lingual foramen, which is extend internally from mandibular canal in right and left sides of the mandible in cadavers (13 sides out of 88 sides) and in dry skulls (43 out of 94 sides) examined. The spinal foramen connected with mental canal occurred at the midline of mandible in 6 cases (6 out of 47 cases) in dry skulls. In this small foramen, the inferior alveolar artery give some branches to the inside of mental region at the anterior mandible and which may be run pass through the lingual canal to the lingual foramen, where they emerge to enter the mylohyoid or anterior belly of digastric muscles. The observations of these are important considerations for surgical placement of dental implants in the region in the mandible. (author)

  18. The imaging appearance of crayons

    International Nuclear Information System (INIS)

    McAllister, Aaron S.; Jones, Blaise V.; Lall, Neil U.; Tawfik, Kareem O.

    2017-01-01

    A crayon fragment was determined to be the source of a foreign body inflammatory process in the masticator space of a 15-month-old boy. The appearance of the crayon on CT and MR imaging was unexpected, leading to a further analysis of the imaging features of crayons. To investigate and characterize the imaging appearance of crayons at CT and MRI. The authors obtained CT and MR images of 22 crayons from three manufacturers and three non-pigmented crayons cast by the authors. CT attenuation of the crayons and diameter of the MRI susceptibility signal dropout were plotted versus brand and color. All crayons demonstrated a longitudinal central hypo-attenuating tract. Crayon attenuation varied by brand and color. All of the crayons demonstrated a signal void on T1 and T2 imaging and signal dropout on susceptibility-weighted imaging, the diameter of which varied by brand and color. Understanding the imaging appearance of crayons could help in the correct identification of a crayon as a foreign body on imaging studies, even when it is located in unusual places. (orig.)

  19. MR appearance of central neurocytoma

    International Nuclear Information System (INIS)

    Chang, K.H.; Han, M.H.; Kim, D.G.; Chi, J.G.; Suh, D.C.; Kim, S.J.; Cha, S.H.; Han, M.C.

    1993-01-01

    To provide a detailed description of the MR appearances of central neurocytoma, MR images of 13 patients with central neurocytoma were retrospectively reviewed and compared with CT examinations. The histology was confirmed by ultrastructural and immunohistochemical studies. In 12 patients the tumors were histologically benign and located in the anterior part of the lateral ventricle, 6 of which extended to the 3rd ventricle. There was one case of a histologically malignant variant involving the thalamus and lateral ventricle. The tumors were primarily solid, but contained cysts (85%, 11/13), calcifications (69%, 9/13), and signal void from tumor vessels (62%, 8/13), frequently producing heterogeneous signal intensity on both T1- and T2-weighted images. Most of the solid portion appeared isointense or slightly hyperintense relative to the cerebral cortex on all MR pulse sequences. Calcifications were iso- or hypointense on MR, making them difficult to characterize with MR alone. Intratumoral hemorrhage was seen in 2 patients on MR but not on CT. Contrast enhancement was variable in degree and pattern. Coronal and sagittal MR images were valuable in evaluating the tumor extent and origin site, and in planning the surgical approach. It is concluded that MR imaging appears to be more useful than CT in the overall evaluation of central neurocytoma, even though calcification is better characterized with CT. (orig.)

  20. The imaging appearance of crayons

    Energy Technology Data Exchange (ETDEWEB)

    McAllister, Aaron S.; Jones, Blaise V. [Cincinnati Children' s Hospital Medical Center, Department of Radiology, Cincinnati, OH (United States); Lall, Neil U. [Cincinnati Children' s Hospital Medical Center, Department of Radiology, Cincinnati, OH (United States); Ochsner Health System, Department of Radiology, New Orleans, LA (United States); Tawfik, Kareem O. [University of Cincinnati College of Medicine, Department of Otolaryngology-Head and Neck Surgery, Cincinnati, OH (United States)

    2017-05-15

    A crayon fragment was determined to be the source of a foreign body inflammatory process in the masticator space of a 15-month-old boy. The appearance of the crayon on CT and MR imaging was unexpected, leading to a further analysis of the imaging features of crayons. To investigate and characterize the imaging appearance of crayons at CT and MRI. The authors obtained CT and MR images of 22 crayons from three manufacturers and three non-pigmented crayons cast by the authors. CT attenuation of the crayons and diameter of the MRI susceptibility signal dropout were plotted versus brand and color. All crayons demonstrated a longitudinal central hypo-attenuating tract. Crayon attenuation varied by brand and color. All of the crayons demonstrated a signal void on T1 and T2 imaging and signal dropout on susceptibility-weighted imaging, the diameter of which varied by brand and color. Understanding the imaging appearance of crayons could help in the correct identification of a crayon as a foreign body on imaging studies, even when it is located in unusual places. (orig.)

  1. Review of the helicity formalism

    International Nuclear Information System (INIS)

    Barreiro, F.; Cerrada, M.; Fernandez, E.

    1972-01-01

    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

  2. Coulomb double helical structure

    Science.gov (United States)

    Kamimura, Tetsuo; Ishihara, Osamu

    2012-01-01

    Structures of Coulomb clusters formed by dust particles in a plasma are studied by numerical simulation. Our study reveals the presence of various types of self-organized structures of a cluster confined in a prolate spheroidal electrostatic potential. The stable configurations depend on a prolateness parameter for the confining potential as well as on the number of dust particles in a cluster. One-dimensional string, two-dimensional zigzag structure and three-dimensional double helical structure are found as a result of the transition controlled by the prolateness parameter. The formation of stable double helical structures resulted from the transition associated with the instability of angular perturbations on double strings. Analytical perturbation study supports the findings of numerical simulations.

  3. Helically linked mirror arrangement

    International Nuclear Information System (INIS)

    Ranjan, P.

    1986-08-01

    A scheme is described for helical linking of mirror sections, which endeavors to combine the better features of toroidal and mirror devices by eliminating the longitudinal loss of mirror machines, having moderately high average β and steady state operation. This scheme is aimed at a device, with closed magnetic surfaces having rotational transform for equilibrium, one or more axisymmetric straight sections for reduced radial loss, a simple geometrical axis for the links and an overall positive magnetic well depth for stability. We start by describing several other attempts at linking of mirror sections, made both in the past and the present. Then a description of our helically linked mirror scheme is given. This example has three identical straight sections connected by three sections having helical geometric axes. A theoretical analysis of the magnetic field and single-particle orbits in them leads to the conclusion that most of the passing particles would be confined in the device and they would have orbits independent of pitch angle under certain conditions. Numerical results are presented, which agree well with the theoretical results as far as passing particle orbits are concerned

  4. Conformal avoidance helical tomotherapy for dogs with nasopharyngeal tumors

    International Nuclear Information System (INIS)

    Welsh, J.S.; Turek, M.; Mackie, T.R.; Miller, P.; Mehta, M.P.; Forrest, L.J.

    2003-01-01

    Helical tomotherapy provides a unique means of delivering intensity-modulated radiation therapy (IMRT) using a novel treatment unit, which merges features of a linear accelerator with a helical CT scanner. Thanks to the CT imaging capacity, targeted regions can be visualized prior to, during, or immediately after each treatment. Such image-guidance through megavoltage CT will allow the realization and refinement of the concept of adaptive radiotherapy - the reconstruction of the actually delivered daily dose (as opposed to planned dose) accompanied by prescription adjustments when appropriate. In addition to this unique feature, helical tomotherapy promises further improvements in the specific avoidance of critical normal structures, i.e. conformal avoidance, the counterpart of conformal therapy. The first definitive treatment protocol using helical tomotherapy is presently underway for dogs with nasopharyngeal tumors. In general, such tumors can be treated with conventional external beam radiation therapy but at the cost of severe ocular toxicity due to the anatomy of the canine head. These are readily measurable toxicities and are almost universal in incidence; therefore, the canine nasopharyngeal tumor presents an ideal model to assess the ability to conformally avoid critical structures. It is hoped that conformal avoidance helical tomotherapy will improve tumor control via dose-escalation while reducing ocular toxicity in these veterinary patients. A total of 10 fractions are scheduled for these patients; the first 3 dogs have all received at least 7 fractions delivered via helical tomotherapy. Although preliminary, the first 3 dogs treated have not shown any evidence of ocular toxicity in this ongoing study

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

    NARCIS (Netherlands)

    van Beek, EJR; Brouwers, Elise M J; 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

  6. The bases for the use of interpolation in helical computed tomography: an explanation for radiologists

    International Nuclear Information System (INIS)

    Garcia-Santos, J. M.; Cejudo, J.

    2002-01-01

    In contrast to conventional computed tomography (CT), helical CT requires the application of interpolators to achieve image reconstruction. This is because the projections processed by the computer are not situated in the same plane. Since the introduction of helical CT. a number of interpolators have been designed in the attempt to maintain the thickness of the reconstructed section as close as possible to the thickness of the X-ray beam. The purpose of this article is to discuss the function of these interpolators, stressing the advantages and considering the possible inconveniences of high-grade curved interpolators with respect to standard linear interpolators. (Author) 7 refs

  7. Chronic eosinophilic pneumonia: CT findings

    International Nuclear Information System (INIS)

    Gutierrez, Haydee; Beccar Varela, Lucia; De Felippi, Maria S.

    2002-01-01

    Objective: To assess the usefulness of computerized tomography (CT) in the diagnosis of chronic eosinophilic pneumonia. Material and Methods: A double helical CT was performed in 6 patients referred to our center because of a chest X-ray with pulmonary infiltrates. Clinical presentation was cough, fever and eosinophilia in peripheral blood. Patients' age ranged from 25 to 55 years; 4 were women and 2 were men, one of the latter had a history of bronchial asthma. All patients received treatment with corticosteroids, with remission of the clinical and radiological parameters. Three patients underwent a control CT. Results: Findings consisted in focal parenchymal alterations, with areas of pulmonary consolidation and areas of 'ground glass' appearance; both patterns coexisted in certain areas. In 3 cases the lesions extended from the apices to the pulmonary bases, with predominance of the upper and middle fields. In 1 patient, there was frank predominance in the left hemi thorax. In another patient, who had a history of asthma, there were signs of pulmonary hyperinflation, with diffuse thickening of the bronchial walls, added to the previously mentioned findings, which involved the entire lung. In the mediastinum, 1 patient had lymph nodes larger than 1 cm, 3 had lymph nodes that were not enlarged but were more numerous than usual, and in the remaining patients no lymph nodes were found. The control CT's showed almost total resolution of the pulmonary infiltrates. Conclusion: The combination of eosinophilia and characteristic pulmonary infiltrates with a likely clinical presentation, associated with an optimal response to treatment with corticosteroids allows to make a reliable diagnosis and avoids the need for a pulmonary biopsy. (author)

  8. High-n helicity-induced shear Alfven eigenmodes

    International Nuclear Information System (INIS)

    Nakajima, N.; Cheng, C.Z.; Okamoto, M.

    1992-05-01

    The high-n Helicity-induced shear Alfven Eigenmodes (HAE) are considered both analytically and numerically for the straight helical magnetic system, where n is the toroidal mode number. The eigenmode equation for the high-n HAE modes is derived along the field line and with the aid of the averaging method is shown to reduce to the Mathieu equation asymptotically. The discrete HAE modes are shown to exist inside the continuum spectrum gaps. The continuous spectrum gaps appear around ω 2 = ω A 2 [N(lι-m)/2] 2 for N = 1,2,.., where ω A is the toroidal Alfven transit frequency, and l, m, and ι are the polarity of helical coils, the toroidal pitch number of helical coils, and the rotational transform, respectively. For the same ω A and ι, the frequency of the helical continuum gap is larger than that of the continuum gap in tokamak plasmas by |l-ι -1 m|. The polarity of helical coils l plays a crucial role in determining the spectrum gaps and the properties of the high-n HAE modes. The spectrum gaps near the magnetic axis are created by the helical ripple with circular flux surfaces for l = 1, and ≥ 3 helicals. For l = 2 helical systems, the spectrum gaps are created by the ellipticity of the flux surfaces. These analytical results for the continuum gaps and the existence of the high-n HAE modes in the continuum gaps are confirmed numerically for the l = 2 case, and we find that the HAE modes exist for mode structures with the even and the odd parities. (author)

  9. Helical Tomotherapy Quality Assurance

    International Nuclear Information System (INIS)

    Balog, John; Soisson, Emilie

    2008-01-01

    Helical tomotherapy uses a dynamic delivery in which the gantry, treatment couch, and multileaf collimator leaves are all in motion during treatment. This results in highly conformal radiotherapy, but the complexity of the delivery is partially hidden from the end-user because of the extensive integration and automation of the tomotherapy control systems. This presents a challenge to the medical physicist who is expected to be both a system user and an expert, capable of verifying relevant aspects of treatment delivery. A related issue is that a clinical tomotherapy planning system arrives at a customer's site already commissioned by the manufacturer, not by the clinical physicist. The clinical physicist and the manufacturer's representative verify the commissioning at the customer site before acceptance. Theoretically, treatment could begin immediately after acceptance. However, the clinical physicist is responsible for the safe and proper use of the machine. In addition, the therapists and radiation oncologists need to understand the important machine characteristics before treatment can proceed. Typically, treatment begins about 2 weeks after acceptance. This report presents an overview of the tomotherapy system. Helical tomotherapy has unique dosimetry characteristics, and some of those features are emphasized. The integrated treatment planning, delivery, and patient-plan quality assurance process is described. A quality assurance protocol is proposed, with an emphasis on what a clinical medical physicist could and should check. Additionally, aspects of a tomotherapy quality assurance program that could be checked automatically and remotely because of its inherent imaging system and integrated database are discussed

  10. 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

  11. Absorbed dose in CT. Comparison by CT dose index

    International Nuclear Information System (INIS)

    Yamamoto, Kenji; Akazawa, Hiroshi; Andou, Takashi

    2002-01-01

    Few reports have discussed the absorbed dose on CT units with increased scanning capacity even with the current widespread adoption of multi-slice CT units. To compare and investigate the dose indexes among CT units, we measured the absorbed dose on CT units operating in Nagano Prefecture Japan. The measurements showed proportionality between phantom absorbed dose and the exposured mAs values in conventional scanning operation. Further, the measurements showed that the absorbed dose in the center of the phantom differed by about 2.1-fold between the highest and lowest levels on individual CT units. Within a single company, multi-slice CT units of the same company gave absorbed doses of about 1.3 to 1.5 times those of conventional single-slice CT units under the same exposured conditions of conventional scanning. When the scanning pitch was reduced in helical scanning, the absorbed dose at the center of the phantom increased. (author)

  12. Feasibility study of helical tomotherapy for total body or total marrow irradiation

    International Nuclear Information System (INIS)

    Hui, Susanta K.; Kapatoes, Jeff; Fowler, Jack; Henderson, Douglas; Olivera, Gustavo; Manon, Rafael R.; Gerbi, Bruce; Mackie, T. R.; Welsh, James S.

    2005-01-01

    Total body radiation (TBI) has been used for many years as a preconditioning agent before bone marrow transplantation. Many side effects still plague its use. We investigated the planning and delivery of total body irradiation (TBI) and selective total marrow irradiation (TMI) and a reduced radiation dose to sensitive structures using image-guided helical tomotherapy. To assess the feasibility of using helical tomotherapy (A) we studied variations in pitch, field width, and modulation factor on total body and total marrow helical tomotherapy treatments. We varied these parameters to provide a uniform dose along with a treatment times similar to conventional TBI (15-30 min). (B) We also investigated limited (head, chest, and pelvis) megavoltage CT (MVCT) scanning for the dimensional pretreatment setup verification rather than total body MVCT scanning to shorten the overall treatment time per treatment fraction. (C) We placed thermoluminescent detectors (TLDs) inside a Rando phantom to measure the dose at seven anatomical sites, including the lungs. A simulated TBI treatment showed homogeneous dose coverage (±10%) to the whole body. Doses to the sensitive organs were reduced by 35%-70% of the target dose. TLD measurements on Rando showed an accurate dose delivery (±7%) to the target and critical organs. In the TMI study, the dose was delivered conformally to the bone marrow only. The TBI and TMI treatment delivery time was reduced (by 50%) by increasing the field width from 2.5 to 5.0 cm in the inferior-superior direction. A limited MVCT reduced the target localization time 60% compared to whole body MVCT. MVCT image-guided helical tomotherapy offers a novel method to deliver a precise, homogeneous radiation dose to the whole body target while reducing the dose significantly to all critical organs. A judicious selection of pitch, modulation factor, and field size is required to produce a homogeneous dose distribution along with an acceptable treatment time. In

  13. Flexible helical yarn swimmers.

    Science.gov (United States)

    Zakharov, A P; Leshansky, A M; Pismen, L M

    2016-09-01

    We investigate the motion of a flexible Stokesian flagellar swimmer realised as a yarn made of two intertwined elastomer fibres, one active, that can reversibly change its length in response to a local excitation causing transition to the nematic state or swelling, and the other one, a passive isotropic elastomer with identical mechanical properties. A propagating chemical wave may provide an excitation mechanism ensuring a constant length of the excited region. Generally, the swimmer moves along a helical trajectory, and the propagation and rotation velocity are very sensitive to the ratio of the excited region to the pitch of the yarn, as well as to the size of a carried load. External excitation by a moving actuating beam is less effective, unless the direction of the beam is adjusted to rotation of the swimmer.

  14. LHD helical divertor

    International Nuclear Information System (INIS)

    Ohyabu, N.; Watanabe, T.; Ji Hantao

    1993-07-01

    The Large Helical Device (LHD) now under construction is a heliotron/torsatron device with a closed divertor system. The edge LHD magnetic structure has been studied in detail. A peculiar feature of the configuration is existence of edge surface layers, a complicated three dimensional magnetic structure which does not, however, seem to hamper the expected divertor functions. Two divertor operational modes are being considered for the LHD experiment, high density, cold radiative divertor operation as a safe heat removal scheme and high temperature divertor plasma operation. In the latter operation, a divertor plasma with temperature of a few kev, generated by efficient pumping, expects to lead to significant improvement in core plasma confinement. Conceptual designs of the LHD divertor components are under way. (author)

  15. Computed Tomography (CT) Scans and Cancer

    Science.gov (United States)

    ... Reporting & Auditing Grant Transfer Grant Closeout Contracts & Small Business Training Cancer Training at NCI (Intramural) Resources for ... companies (and Medicare) do not currently reimburse the costs of this procedure. Also, because CT ... the effectiveness of low-dose helical CT for lung cancer ...

  16. Computed tomography appearances of sclerosing encapsulating peritonitis

    International Nuclear Information System (INIS)

    George, C.; Al-Zwae, K.; Nair, S.; Cast, J.E.I.

    2007-01-01

    Sclerosing encapsulating peritonitis (SEP) is a serious complication of peritoneal dialysis (PD) characterized by thickened peritoneal membranes, which lead to decreased ultra-filtration and intestinal obstruction. Its early clinical features are nonspecific, and it is often diagnosed late following laparotomy and peritoneal biopsy, when the patient develops small bowel obstruction, which can be a life-threatening complication. However, this is changing with increasing awareness of computed tomography (CT) findings in SEP. CT can yield an early, non-invasive diagnosis that may improve patient outcome. We present a review of the CT appearances of SEP

  17. Computed tomography appearances of sclerosing encapsulating peritonitis

    Energy Technology Data Exchange (ETDEWEB)

    George, C. [Department of Radiology, Hull Royal Infirmary, Hull (United Kingdom)]. E-mail: cheriangeorge@hotmail.com; Al-Zwae, K. [Department of Radiology, Hull Royal Infirmary, Hull (United Kingdom); Nair, S. [Department of Radiology, Hull Royal Infirmary, Hull (United Kingdom); Cast, J.E.I. [Department of Radiology, Hull Royal Infirmary, Hull (United Kingdom)

    2007-08-15

    Sclerosing encapsulating peritonitis (SEP) is a serious complication of peritoneal dialysis (PD) characterized by thickened peritoneal membranes, which lead to decreased ultra-filtration and intestinal obstruction. Its early clinical features are nonspecific, and it is often diagnosed late following laparotomy and peritoneal biopsy, when the patient develops small bowel obstruction, which can be a life-threatening complication. However, this is changing with increasing awareness of computed tomography (CT) findings in SEP. CT can yield an early, non-invasive diagnosis that may improve patient outcome. We present a review of the CT appearances of SEP.

  18. Impact of polychromatic x-ray sources on helical, cone-beam computed tomography and dual-energy methods

    International Nuclear Information System (INIS)

    Sidky, Emil Y; Zou Yu; Pan Xiaochuan

    2004-01-01

    Recently, there has been much work devoted to developing accurate and efficient algorithms for image reconstruction in helical, cone-beam computed tomography (CT). Little attention, however, has been directed to the effect of physical factors on helical, cone-beam CT image reconstruction. This work investigates the effect of polychromatic x-rays on image reconstruction in helical, cone-beam computed tomography. A pre-reconstruction dual-energy technique is developed to reduce beam-hardening artefacts and enhance contrast in soft tissue

  19. Theoretical aspects of magnetic helicity

    International Nuclear Information System (INIS)

    Hammer, J.H.

    1985-01-01

    The magnetic helicity, usually defined as K=integralA.Bdv, where A is the vector potential and B the magnetic field, measures the topological linkage of magnetic fluxes. Helicity manifests itself in the twistedness and knottedness of flux tubes. Its significance is that it is an ideal MHD invariant. While the helicity formalism has proven very useful in understanding reversed field pinch and spheromak behavior, some problems exist in applying the method consistently for complex (e.g., toroidal) conductor geometries or in situations where magnetic flux penetrates conducting walls. Recent work has attempted to generalize K to allow for all possible geometries

  20. Imaging Features of Helical Computed Tomography Suggesting Advanced Urothelial Carcinoma Arising from the Pelvocalyceal System

    International Nuclear Information System (INIS)

    Kwak, Kyung Won; Park, Byung Kwan; Kim, Chan Kyo; Lee, Hyun Moo; Choi, Han Y ong

    2008-01-01

    Background: Urothelial carcinoma is the most common malignant tumor arising from the pelvocalyceal system. Helical computed tomography (CT) is probably the best preoperative-stage modality for the determination of treatment plan and prognosis. Purpose: To obtain helical CT imaging features suggesting advanced pelvocalyceal urothelial carcinoma. Material and Methods: Preoperative CT images in 44 patients with pelvocalyceal urothelial carcinoma were retrospectively reviewed and correlated with the pathological examination to determine imaging features suggesting stage III or IV of the disease. Results: Pathological stages revealed stage I in 16, stage II in three, stage III in 17, and stage IV in eight patients. Seven patients had metastatic lymph nodes. CT imaging showed that renal parenchymal invasion, sinus fat invasion, and lymph node metastasis were highly suggestive of advanced urothelial cell carcinoma (P<0.05). Helical CT sensitivity, specificity, and accuracy for advanced pelvocalyceal urothelial carcinoma were 76% (19/25), 84% (16/19), and 80% (35/44), respectively. Conclusion: Preoperative helical CT may suggest imaging features of advanced urothelial carcinoma, influencing treatment plan and patient prognosis, even though its accuracy is not so high

  1. Godbillon Vey Helicity and Magnetic Helicity in Magnetohydrodynamics

    Science.gov (United States)

    Webb, G. M.; Hu, Q.; Anco, S.; Zank, G. P.

    2017-12-01

    The Godbillon-Vey invariant arises in homology theory, and algebraic topology, where conditions for a layered family of 2D surfaces forms a 3D manifold were elucidated. The magnetic Godbillon-Vey helicity invariant in magnetohydrodynamics (MHD) is a helicity invariant that occurs for flows, in which the magnetic helicity density hm= A\\cdotB=0 where A is the magnetic vector potential and B is the magnetic induction. Our purpose is to elucidate the evolution of the magnetic Godbillon-Vey field η =A×B/|A|2 and the Godbillon-Vey helicity hgv}= η \\cdot∇ × η in general MHD flows in which the magnetic helicity hm≠q 0. It is shown that hm acts as a source term in the Godbillon-Vey helicity transport equation, in which hm is coupled to hgv via the shear tensor of the background flow. The transport equation for hgv depends on the electric field potential ψ , which is related to the gauge for A, which takes its simplest form for the advected A gauge in which ψ =A\\cdot u where u is the fluid velocity.

  2. Helicity multiplexed broadband metasurface holograms.

    Science.gov (United States)

    Wen, Dandan; Yue, Fuyong; Li, Guixin; Zheng, Guoxing; Chan, Kinlong; Chen, Shumei; Chen, Ming; Li, King Fai; Wong, Polis Wing Han; Cheah, Kok Wai; Pun, Edwin Yue Bun; Zhang, Shuang; Chen, Xianzhong

    2015-09-10

    Metasurfaces are engineered interfaces that contain a thin layer of plasmonic or dielectric nanostructures capable of manipulating light in a desirable manner. Advances in metasurfaces have led to various practical applications ranging from lensing to holography. Metasurface holograms that can be switched by the polarization state of incident light have been demonstrated for achieving polarization multiplexed functionalities. However, practical application of these devices has been limited by their capability for achieving high efficiency and high image quality. Here we experimentally demonstrate a helicity multiplexed metasurface hologram with high efficiency and good image fidelity over a broad range of frequencies. The metasurface hologram features the combination of two sets of hologram patterns operating with opposite incident helicities. Two symmetrically distributed off-axis images are interchangeable by controlling the helicity of the input light. The demonstrated helicity multiplexed metasurface hologram with its high performance opens avenues for future applications with functionality switchable optical devices.

  3. Overview of quasi single helicity experiments in reversed field pinches

    International Nuclear Information System (INIS)

    Martin, P.; Marrelli, L.; Spizzo, G.

    2003-01-01

    We report the results of an experimental and theoretical project dedicated to the study of Quasi Single Helicity Reversed Field Pinch plasmas. The project has involved several RFP devices and numerical codes. It appears that QSH spectra are a feature common to all the experiments. (author)

  4. Employing helicity amplitudes for resummation

    International Nuclear Information System (INIS)

    Moult, Ian; Stewart, Iain W.; Tackmann, Frank J.; Waalewijn, Wouter J.; Amsterdam Univ.

    2015-08-01

    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 matching coefficients, for pp → H+0,1,2 jets, pp → W/Z/γ+0,1,2 jets, and pp → 2,3 jets. These operator bases are completely crossing symmetric, so the results can easily be applied to processes with e + e - and e - p collisions.

  5. Study of Pelvicaliceal Anatomy by Helical Computerized Tomography

    International Nuclear Information System (INIS)

    Al-Qahtani, Fahd N.; Ali, Gaber A.; Kamal, Baher A.; Taha, Saud A.

    2003-01-01

    To evaluate the role of 3-dimensional images produced by computerized tomography (CT), using intravenous contrast, to study pelvicaliceal anatomy.This might be of help in endourological procedure. The study was conducted in the King Fahd Hospital of the University, King Faisal University. Dammam,Kingdom of Saudi Arabia. The study took place from July 2002 through to October 2002 .Helical CT was carried for patients who were investigated using excretory urography for any reason. A CT was carried out to the kidneys only within 10 minutes ( between 5 and 15 minute films of excretory urography).Images were reprocessed by 3-dimension construction after subtracting all structures except for the palvicaliceal system. Thity-six normal kidneys were studied. The upper pole was drained by a single caliceal infundibulum in all 36(100%) kidneys.the middle segement of the kidney was drained by 2 infundibula in 32 (89%) kidneys. Four (11%) kidneys have no middle caliceal infudibula. The lower pole was drained by 2 caliceal infundibula in 23 (64%) and a single infundibulum in 13 (36%) kidneys. The minor calices draining each renal segment were seen clearly. Three-dimensional images derived by helical CT are feasible for evaluating the anatomy of palvicaliceal system,and, can be of help in endourological procedures. (author)/

  6. Optimizing radiation exposure for CT localizer radiographs

    Energy Technology Data Exchange (ETDEWEB)

    Bohrer, Evelyn; Maeder, Ulf; Fiebich, Martin [Univ. of Applied Sciences, Giessen (Germany). Inst. of Medical Physics and Radiation Protection-IMPS; Schaefer, Stefan; Krombach, Gabriele A. [Univ. Hospital Giessen (Germany). Dept. of Radiology; Noel, Peter B. [Technische Univ. Muenchen (Germany). Dept. of Diagnostic and Interventional Radiology

    2017-08-01

    The trend towards submillisievert CT scans leads to a higher dose fraction of localizer radiographs in CT examinations. The already existing technical capabilities make dose optimization of localizer radiographs worthwhile. Modern CT scanners apply automatic exposure control (AEC) based on attenuation data in such a localizer. Therefore not only this aspect but also the detectability of anatomical landmarks in the localizer for the desired CT scan range adjustment needs to be considered. The effective dose of a head, chest, and abdomen-pelvis localizer radiograph with standard factory settings and user-optimized settings was determined using Monte Carlo simulations. CT examinations of an anthropomorphic phantom were performed using multiple sets of acquisition parameters for the localizer radiograph and the AEC for the subsequent helical CT scan. Anatomical landmarks were defined to assess the image quality of the localizer. CTDI{sub vol} and effective mAs per slice of the helical CT scan were recorded to examine the impact of localizer settings on a helical CT scan. The dose of the localizer radiograph could be decreased by more than 90% while the image quality remained sufficient when selecting the lowest available settings (80 kVp, 20 mA, pa tube position). The tube position during localizer acquisition had a greater impact on the AEC than the reduction of tube voltage and tube current. Except for the use of a pa tube position, all changes of acquisition parameters for the localizer resulted in a decreased total radiation exposure. A dose reduction of CT localizer radiograph is necessary and possible. In the examined CT system there was no negative impact on the modulated helical CT scan when the lowest tube voltage and tube current were used for the localizer.

  7. Recent helicity source and power supply improvements in CTX

    International Nuclear Information System (INIS)

    Henins, I.; Knox, S.O.; Jarboe, T.R.; Barnes, C.W.

    1985-01-01

    Since the last CT Symposium, two major changes in CTX have been the introduction of pulse forming networks (PFNs) to drive the coaxial electrode helicity source, and the very recent installation of a larger source with electrode diameters about twice of the previous ones. The power supplies used for CTX have ranged from the simple connection of the capacitor bank across the electrode collector plates (slow mode) to the more sophisticated PFNs, described here, which optimize the energy transfer from the capacitor bank to the magnetic fields of the spheromak. Using the PFNs, the formation and sustainment phase to peak toroidal plasma current lasts longer (approx. =0.7 ms) than in the slow mode (approx. =0.05 ms), thus lowering the peak current that must flow through the electrode surfaces. Also, by supplying the source electrodes with both a square pulse current waveform and a quasi-steady source flux, phi/sub g/, one can generate helicity at a constant source lambda/sub g/ parameter. The use of a larger diameter helicity source will improve the energy efficiency of helicity injection and allow higher source current for the same surface current density because of the larger electrode surface area

  8. Utility of bolus dynamic CT for the detection of hypervascular malignant hepatic tumors. Mainly referring to the comparison with delayed phase contrast-enhanced CT

    International Nuclear Information System (INIS)

    Matsuda, Hiromichi; Abe, Kimihiko; Freeny, P.C.

    1996-01-01

    In order to analyze the usefulness of dynamic contrast-enhanced CT, 84 patients who had hepatocellular carcinoma or suspected hypervascular metastases were studied with conventional incremental dynamic CT (CID-CT) or double helical CT (DH-CT). Delayed phase contrast-enhanced CT studies were consecutively performed in all patients. Thirty-six of 84 patients had malignant hepatic neoplasms; six had hepatocellular carcinoma and 30 had metastatic tumors. At first, the detectability of hepatic lesions was evaluated with bolus dynamic CT and delayed phase CT. Dynamic CT has detected more lesions than delayed CT. Some hepatic lesions described as isodensity were missed on CID-CT. Therefore, delayed phase CT cannot be eliminated when CID-CT is performed. Secondly, hepatic lesion detectability with CID-CT was compared with that of DH-CT. DH-CT did not miss the hepatic lesions picked up by delayed phase CT and was expected to provide excellent detectability of hypervascular hepatic neoplasms. In addition, first helical CT showed most hepatic lesions as areas of obvious hyperdensity, while CID-CT did not show their correct vascularities. So-called hypervascular hepatic tumors, however, were not always hypervascular and were demonstrated as areas of iso-hypodensity even on initial helical scanning. Second helical CT was useful to detect these so-called hypervascular, but actually hypovascular lesions. In conclusion, dynamic CT was helpful in detecting hypervascular hepatic malignant neoplasms, and DH-CT was more accurate than-CID-CT for the detection of hepatic lesions and the evaluation of vascular lesion. (author)

  9. Helical bifurcation and tearing mode in a plasma—a description based on Casimir foliation

    International Nuclear Information System (INIS)

    Yoshida, Z; Dewar, R L

    2012-01-01

    The relation between the helical bifurcation of a Taylor relaxed state (a Beltrami equilibrium) and a tearing mode is analyzed in a Hamiltonian framework. Invoking an Eulerian representation of the Hamiltonian, the symplectic operator (defining a Poisson bracket) becomes non-canonical, i.e. the symplectic operator has a nontrivial cokernel (dual to its nullspace), foliating the phase space into level sets of Casimir invariants. A Taylor relaxed state is an equilibrium point on a Casimir (helicity) leaf. Changing the helicity, equilibrium points may bifurcate to produce helical relaxed states; a necessary and sufficient condition for bifurcation is derived. Tearing yields a helical perturbation on an unstable equilibrium, producing a helical structure approximately similar to a helical relaxed state. A slight discrepancy found between the helically bifurcated relaxed state and the linear tearing mode viewed as a perturbed, singular equilibrium state is attributed to a Casimir element (named ‘helical flux’) pertinent to a ‘resonance singularity’ of the non-canonical symplectic operator. While the helical bifurcation can occur at discrete eigenvalues of the Beltrami parameter, the tearing mode, being a singular eigenfunction, exists for an arbitrary Beltrami parameter. Bifurcated Beltrami equilibria appearing on the same helicity leaf are isolated by the helical-flux Casimir foliation. The obstacle preventing the tearing mode to develop in the ideal limit turns out to be the shielding current sheet on the resonant surface, preventing the release of the ‘potential energy’. When this current is dissipated by resistivity, reconnection is allowed and tearing instability occurs. The Δ′ criterion for linear tearing instability of Beltrami equilibria is shown to be directly related to the spectrum of the curl operator. (paper)

  10. Pulling Helices inside Bacteria: Imperfect Helices and Rings

    Science.gov (United States)

    Allard, Jun F.; Rutenberg, Andrew D.

    2009-04-01

    We study steady-state configurations of intrinsically-straight elastic filaments constrained within rod-shaped bacteria that have applied forces distributed along their length. Perfect steady-state helices result from axial or azimuthal forces applied at filament ends, however azimuthal forces are required for the small pitches observed for MreB filaments within bacteria. Helix-like configurations can result from distributed forces, including coexistence between rings and imperfect helices. Levels of expression and/or bundling of the polymeric protein could mediate this coexistence.

  11. Kinetic theory of rf current drive and helicity injection

    International Nuclear Information System (INIS)

    Mett, R.R.

    1992-01-01

    Current drive and helicity injection by plasma waves are examined with the use of kinetic theory. The Vlasov equation yields a general current drive formula that contains resonant and nonresonant (ponderomotivelike) contributions. Standard quasilinear current drive is described by the former, while helicity current drive may be contained in the latter. Since direct analytical comparison of the sizes of the two terms is, in general, difficult, a new approach is taken. Solution of the drift-kinetic equation shows that the standard Landau damping/transit time magnetic pumping quasilinear diffusion coefficient is the only contribution to steady-state current drive to leading order in ε=ρ L /l, where ρ L is the Larmor radius and l is the inhomogeneity scale length. All nonresonant contributions, including the helicity, appear at higher order, after averages are taken over a flux surface, over azimuth, and over time. Consequently, at wave frequencies well below the electron cyclotron frequency, a wave helicity flux perpendicular to the magnetic field does not influence the parallel motion of electrons to leading order and therefore will not drive a significant current. Any current associated with a wave helicity flux is then either ion current (and thus inefficient) or electron current stemming from effects not included in the drift-kinetic treatment, such as cyclotron, collisional, or nonlinear (i.e., not quasilinear)

  12. l=1 helical axis heliotron device in Kyoto university

    International Nuclear Information System (INIS)

    Nagasaki, K.; Sano, F.; Mizuuchi, T.; Hanatani, K.; Okada, H.; Obiki, T.

    1999-01-01

    Helical systems are an attractive candidate for magnetic fusion reactor. Recently, there has been great progress in theoretical research of three dimensional magnetic field structures, resulting in several kinds of confinement optimization being proposed for toroidal magnetic confinement system. For example, some sophisticated ideas have appeared on stage such as quasi-helical symmetry and quasi-isodynamic system. To find experimentally which way is the best Optimisation, a new helical axis heliotron device, so called 'Heliotron J', is under construction in the Institute of Advanced Energy, Kyoto University, Japan. In this conference, the basic concept and the present status will be presented. In the conventional plane axis helical system, it was difficult to have both good particle confinement and good MHD stability simultaneously. The goal of Heliotron J project is to clarify their compatibility in the spatial axis toroidal device. The best way for Optimising the helical magnetic field configuration will be explored by investigating the plasma response to the change in the field components. The main subjects for plasma experiment are: demonstration of the existence of good magnetic flux surfaces, reduction of neoclassical transport in collisionless regime, MHD Stabilisation in high β plasma, controllability of bootstrap current, good confinement of high energy particles

  13. Radiation dosage of various CT-methods in lung diagnostics

    International Nuclear Information System (INIS)

    Heinz-Peer, G.; Weninger, F.; Nowotny, R.; Herold, C.J.

    1996-01-01

    Introduction of the computed tomography index CTDI and the multiple scan average dose (MSAD) has led to standardization of the dose description in CT examinations. Despite the use of these dose parameters, many different dosages are reported in the literature for different CT methods. In addition, there is still a wide range of radiation dosimetry results reported for conventional CT, helical CT, and HRCT used in chest examinations. The variations in dosage are mainly due to difference in factors affecting the dose, i.e. beam geometry, beam quality, scanner geometry ('generation'), and operating parameters. In addition, CT dosimetry instrumentation and methodology make a contribution to dosages. Recent studies calculating differences in factors affecting dosage and CT dosimetry and using similar operating parameters, show similar results in CT dosimetry for conventional and helical CT. On the other hand, dosages for HRCT were greatly reduced. This was mainly caused by narrow beam collimation and increasing section spacing. (orig.) [de

  14. On Multiple Appearances

    DEFF Research Database (Denmark)

    Bork Petersen, Franziska

    2012-01-01

    reduction and epoché to focus on how dancing bodies appear in a stage context. To test these tools’ ability to explore dancing bodies from a third-person perspective, I analyse the Danish choreographer Kitt Johnson’s solo performance Drift (2011) - focussing on her shifting physical appearance. While...... phenomenology helps me to describe the multiple and radically different guises that Johnson assumes in her piece, my analysis, ultimately, does not aim to distil a truer, more real being from her appearances as is often the case in phenomenological philosophy. I complement my analytical approach...... with the Deleuzian notion of becoming animal and suggest that Johnson stages what could, in Judith Butler’s terms, be called a critical contingency of bodily appearance....

  15. Transport barrier in Helical system

    International Nuclear Information System (INIS)

    Ida, Katsumi

    1998-01-01

    Experiments on the transport barrier in Helical plasmas are reviewed. There are two mechanisms of transport improvement, that results in the formation of the transport barrier. One is the improvement of neoclassical transport by reducing the ripple loss with radial electric field, which exist only in helical plasma. The other is the improvement of anomalous transport due to the suppression of fluctuations associated with a radial electric field shear both in tokamak and helical plasma. The formation of the transport barrier can be triggered by the radial electric field shear associated with the transition of the radial electric field (L/H transition or ion-electron root transition) or the peaked density or the optimization of magnetic field shear. The mechanisms of transport barrier formation are also discussed. (author). 60 refs

  16. 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.

  17. Generalized helicity and Beltrami fields

    International Nuclear Information System (INIS)

    Buniy, Roman V.; Kephart, Thomas W.

    2014-01-01

    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 ∫ Ω trF μν F μν d 4 x subject to the local constraint ε μναβ trF μν F 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

  18. Toroidal helical quartz forming machine

    International Nuclear Information System (INIS)

    Hanks, K.W.; Cole, T.R.

    1977-01-01

    The Scyllac fusion experimental machine used 10 cm diameter smooth bore discharge tubes formed into a simple toroidal shape prior to 1974. At about that time, it was discovered that a discharge tube was required to follow the convoluted shape of the load coil. A machine was designed and built to form a fused quartz tube with a toroidal shape. The machine will accommodate quartz tubes from 5 cm to 20 cm diameter forming it into a 4 m toroidal radius with a 1 to 5 cm helical displacement. The machine will also generate a helical shape on a linear tube. Two sets of tubes with different helical radii and wavelengths have been successfully fabricated. The problems encountered with the design and fabrication of this machine are discussed

  19. Helical axis stellarator equilibrium model

    International Nuclear Information System (INIS)

    Koniges, A.E.; Johnson, J.L.

    1985-02-01

    An asymptotic model is developed to study MHD equilibria in toroidal systems with a helical magnetic axis. Using a characteristic coordinate system based on the vacuum field lines, the equilibrium problem is reduced to a two-dimensional generalized partial differential equation of the Grad-Shafranov type. A stellarator-expansion free-boundary equilibrium code is modified to solve the helical-axis equations. The expansion model is used to predict the equilibrium properties of Asperators NP-3 and NP-4. Numerically determined flux surfaces, magnetic well, transform, and shear are presented. The equilibria show a toroidal Shafranov shift

  20. Resonant helical fields in tokamaks

    International Nuclear Information System (INIS)

    Okano, V.

    1990-01-01

    Poincare maps of magnetic field lines of a toroidal helical system were made. The magnetic field is a linear superposition of the magnetic fields produced by a toroidal plasma in equilibrium and by external helical currents. Analytical expression for the Poincare maps was no obtained since the magnetic field do not have symmetry. In order to obtain the maps, the equation minus derivative of l vector times B vector = 0 was numerically integrated. In the Poincare maps, the principal and the secondary magnetic island were observed. (author)

  1. Helical tomotherapy. Experiences of the first 150 patients in Heidelberg

    Energy Technology Data Exchange (ETDEWEB)

    Sterzing, F.; Schubert, K.; Sroka-Perez, G.; Kalz, J.; Debus, J.; Herfarth, K. [Dept. of Radiation Oncology, Univ. of Heidelberg (Germany)

    2008-01-15

    Background and purpose: helical tomotherapy was introduced into clinical routine at the Department of Radiation Oncology, University Hospital of Heidelberg, Germany, in July 2006. This report is intended to describe the experience with the first 150 patients treated with helical tomotherapy. Patient selection, time effort, handling of daily image guidance with megavoltage (MV) CT, and quality of radiation plans shall be assessed. Patients and methods: between July 2006 and May 2007, 150 patients were treated with helical tomotherapy in the University Hospital of Heidelberg. Mean age was 60 years with a minimum of 30 years and a maximum of 85 years. 79 of these patients received radiotherapy as a part of multimodal treatment pre- or postoperatively, 17 patients received treatment as a combined radiochemotherapy. 76% were treated with curative intent. Radiotherapy sites were central nervous system (n = 7), head and neck (n = 28), thoracic (n = 37), abdominal (n = 58) and skeletal system (n = 20). Most common tumor entities were prostate cancer (n = 28), breast cancer (n = 17), gastrointestinal tumors (n = 19), pharyngeal carcinoma (n = 14), lymphoma (n = 13), metastatic disease (bone n = 14, liver n = 6, lung n = 4, lymph node n = 2), sarcoma (n = 8), malignant pleural mesothelioma (n = 5), ovarian cancer treated with whole abdominal irradiation (n = 4), lung cancer (n = 3), skin malignancies (n = 3), chordoma (n = 2), meningioma (n = 2), one ependymoma and one medulloblastoma treated with craniospinal axis irradiation (n = 2), and others (n = 4). Nine patients were treated with single-fraction radiosurgery, nine with image-guided spinal reirradiation, and twelve patients were treated at multiple targets simultaneously. A pretreatment MV-CT scan was performed in 98.2% of the 3,026 fractions applied. After matching with the kilovoltage planning CT, corrections for translations and rotation around longitudinal axis (roll) were done. Results: mean time on table was 24

  2. Helical system. History and current state of helical research

    International Nuclear Information System (INIS)

    Yokoyama, Masayuki

    2017-01-01

    This paper described the following: (1) history of nuclear fusion research of Japan's original heliotron method, (2) worldwide development of nuclear fusion research based on helical system such as stellarator, and (3) worldwide meaning of large helical device (LHD) aiming to demonstrate the steady-state performance of heliotron type in the parameter area extrapolable to the core plasma, and research results of LHD. LHD demonstrated that the helical system is excellent in steady operation performance at the world's most advanced level. In an experiment using deuterium gas in 2017, LHD achieved to reach 120 million degrees of ion temperature, which is one index of nuclear fusion condition, demonstrated the realization of high-performance plasma capable of extrapolating to future nuclear fusion reactors, and established the foundation for full-scale research toward the realization of nuclear fusion reactor. Besides experimental research, this paper also described the helical-type stationary nuclear fusion prototype reactor, FFHR-d1, which was based on progress of large-scale simulation at the world's most advanced level. A large-scale superconducting stellarator experimental device, W7-X, with the same scale as LHD, started experiment in December 2015, whose current state is also touched on here. (A.O.)

  3. Helicity and evanescent waves. [Energy transport velocity, helicity, Lorentz transformation

    Energy Technology Data Exchange (ETDEWEB)

    Agudin, J L; Platzeck, A M [La Plata Univ. Nacional (Argentina); Albano, J R [Instituto de Astronomia y Fisica del Espacio, Buenos Aires, Argentina

    1978-02-20

    It is shown that the projection of the angular momentum of a circularly polarized electromagnetic evanescent wave along the mean velocity of energy transport (=helicity) can be reverted by a Lorentz transformation, in spite of the fact that this velocity is c.

  4. Wedgelet Enhanced Appearance Models

    DEFF Research Database (Denmark)

    Darkner, Sune; Larsen, Rasmus; Stegmann, Mikkel Bille

    2004-01-01

    Statistical region-based segmentation methods such as the Active Appearance Model (AAM) are used for establishing dense correspondences in images based on learning the variation in shape and pixel intensities in a training set. For low resolution 2D images correspondences can be recovered reliably....... The wedgelet regression trees employed are based on triangular domains and estimated using cross validation. The wedgelet regression trees are functional descriptions of the intensity information and serve to 1) reduce noise and 2) produce a compact textural description. The wedgelet enhanced appearance model...

  5. Parameterization and measurements of helical magnetic fields

    International Nuclear Information System (INIS)

    Fischer, W.; Okamura, M.

    1997-01-01

    Magnetic fields with helical symmetry can be parameterized using multipole coefficients (a n , b n ). We present a parameterization that gives the familiar multipole coefficients (a n , b n ) for straight magnets when the helical wavelength tends to infinity. To measure helical fields all methods used for straight magnets can be employed. We show how to convert the results of those measurements to obtain the desired helical multipole coefficients (a n , b n )

  6. 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....

  7. ICRF heating on helical devices

    International Nuclear Information System (INIS)

    Rasmussen, D.A.; Lyon, J.F.; Hoffman, D.J.; Murakami, M.; England, A.C.; Wilgen, J.B.; Jaeger, E.F.; Wang, C.; Batchelor, D.B.

    1995-01-01

    Ion cyclotron range of frequency (ICRF) heating is currently in use on CHS and W7-AS and is a major element of the heating planned for steady state helical devices. In helical devices, the lack of a toroidal current eliminates both disruptions and the need for ICRF current drive, simplifying the design of antenna structures as compared to tokamak applications. However the survivability of plasma facing components and steady state cooling issues are directly applicable to tokamak devices. Results from LHD steady state experiments should be available on a time scale to strongly influence the next generation of steady state tokamak experiments. The helical plasma geometry provides challenges not faced with tokamak ICRF heating, including the potential for enhanced fast ion losses, impurity accumulation, limited access for antenna structures, and open magnetic field lines in the plasma edge. The present results and near term plans provide the basis for steady state ICRF heating of larger helical devices. An approach which includes direct electron, mode conversion, ion minority and ion Bernstein wave heating addresses these issues

  8. ICRF heating on helical devices

    International Nuclear Information System (INIS)

    Rasmussen, D.A.; Lyon, J.F.; Hoffman, D.J.

    1995-01-01

    Ion cyclotron range of frequency (ICRF) heating is currently in use on CHS and W7AS and is a major element of the heating planned for steady state helical devices. In helical devices, the lack of a toroidal current eliminates both disruptions and the need for ICRF current drive, simplifying the design of antenna structures as compared to tokamak applications. However the survivability of plasma facing components and steady state cooling issues are directly applicable to tokamak devices. Results from LHD steady state experiments should be available on a time scale to strongly influence the next generation of steady state tokamak experiments. The helical plasma geometry provides challenges not faced with tokamak ICRF heating, including the potential for enhanced fast ion losses, impurity accumulation, limited access for antenna structures, and open magnetic field lines in the plasma edge. The present results and near term plans provide the basis for steady state ICRF heating of larger helical devices. An approach which includes direct electron, mode conversion, ion minority and ion Bernstein wave heating addresses these issues

  9. CT evaluation of hepatocellular carcinomas supplied by right inferior phrenic arteries

    International Nuclear Information System (INIS)

    Wen Ming; Zhu Mingxia; Huang Yonghuo

    2002-01-01

    Objective: To evaluate the CT appearance of the hepatocellular carcinomas (HCC) supplied by the right inferior phrenic arteries (RIPA). Methods: A total of 195 consecutive cases of HCCs examined with helical CT and arteriography were studied. 15 proven HCCs cases were supplied by the RIPA. On arterial-phase CT images, the size of the RIPA, the left inferior phrenic arteries, and HCCs were measured, and the origin of RIPA and the location of HCCs were recorded. The CT findings in these 15 cases were correlated with arterio-graphic images. Results: CT showed RIPA on the right diaphragmatic crus as high attenuation in all patients. The origin of RIPA was demonstrated in 11 cases. The diameter of the RIPA (3.1 +- 1.1) mm was larger than that of the left inferior phrenic artery (1.3 +- 0.4) mm (P < 0.05). Conclusion: On CT images, if the RIPA asymmetrically dilates, and its diameter is larger than 2.5 mm, it is suggested that the HCC is supplied by the RIPA

  10. Respiratory gated lung CT using 320-row area detector CT

    International Nuclear Information System (INIS)

    Sakamoto, Ryo; Noma, Satoshi; Higashino, Takanori

    2010-01-01

    Three hundred and twenty-row Area Detector CT (ADCT) has made it possible to scan whole lung field with prospective respiratory gated wide volume scan. We evaluated whether the respiratory gated wide volume scan enables to reduce motion induced artifacts in the lung area. Helical scan and respiratory gated wide volume scan were performed in 5 patients and 10 healthy volunteers under spontaneous breathing. Significant reduction of motion artifact and superior image quality were obtained in respiratory gated scan in comparison with helical scan. Respiratory gated wide volume scan is an unique method using ADCT, and is able to reduce motion artifacts in lung CT scans of patients unable to suspend respiration in clinical scenes. (author)

  11. Abdominal and Pelvic CT

    Medline Plus

    Full Text Available ... CD or DVD. CT images of internal organs, bones, soft tissue and blood vessels provide greater detail ... image on a special electronic image recording plate. Bones appear white on the x-ray; soft tissue, ...

  12. Computed Tomography (CT) -- Head

    Medline Plus

    Full Text Available ... liver, shows up in shades of gray, and air appears black. With CT scanning, numerous x-ray ... cause blurring of the images and degrade the quality of the examination the same way that it ...

  13. Abdominal and Pelvic CT

    Medline Plus

    Full Text Available ... liver, shows up in shades of gray, and air appears black. With CT scanning, numerous x-ray ... cause blurring of the images and degrade the quality of the examination the same way that it ...

  14. Computed Tomography (CT) -- Sinuses

    Medline Plus

    Full Text Available ... up in shades of gray, and air appears black. With CT scanning, numerous x-ray beams and ... Safety page for more information about radiation dose. Women should always inform their physician and x-ray ...

  15. Abdominal and Pelvic CT

    Medline Plus

    Full Text Available ... up in shades of gray, and air appears black. With CT scanning, numerous x-ray beams and ... Safety page for more information about radiation dose. Women should always inform their physician and x-ray ...

  16. Computed Tomography (CT) -- Head

    Medline Plus

    Full Text Available ... up in shades of gray, and air appears black. With CT scanning, numerous x-ray beams and ... Safety page for more information about radiation dose. Women should always inform their physician and x-ray ...

  17. Texture Enhanced Appearance Models

    DEFF Research Database (Denmark)

    Larsen, Rasmus; Stegmann, Mikkel Bille; Darkner, Sune

    2007-01-01

    Statistical region-based registration methods such as the Active Appearance Model (AAM) are used for establishing dense correspondences in images. At low resolution, images correspondences can be recovered reliably in real-time. However, as resolution increases this becomes infeasible due...... representation are superior to wavelet representations at high dimensionality-reduction rates. At low reduction rates an edge enhanced wavelet representation provides better segmentation accuracy than the full standard AAM model....

  18. Musculoskeletal infections: ultrasound appearances

    Energy Technology Data Exchange (ETDEWEB)

    Chau, C.L.F. [Department of Radiology, North District Hospital, NTEC, Fanling, NT, Hong Kong (China)]. E-mail: c8681@yahoo.com; Griffith, J.F. [Department of Diagnostic Radiology and Organ Imaging, Prince of Wales Hospital, NTEC, Shatin, NT, Hong Kong (China)

    2005-02-01

    Musculoskeletal infections are commonly encountered in clinical practice. This review will discuss the ultrasound appearances of a variety of musculoskeletal infections such as cellulitis, infective tenosynovitis, pyomyositis, soft-tissue abscesses, septic arthritis, acute and chronic osteomyelitis, and post-operative infection. The peculiar sonographic features of less common musculoskeletal infections, such as necrotizing fasciitis, and rice body formation in atypical mycobacterial tenosynovitis, and bursitis will also be presented.

  19. Musculoskeletal infections: ultrasound appearances

    International Nuclear Information System (INIS)

    Chau, C.L.F.; Griffith, J.F.

    2005-01-01

    Musculoskeletal infections are commonly encountered in clinical practice. This review will discuss the ultrasound appearances of a variety of musculoskeletal infections such as cellulitis, infective tenosynovitis, pyomyositis, soft-tissue abscesses, septic arthritis, acute and chronic osteomyelitis, and post-operative infection. The peculiar sonographic features of less common musculoskeletal infections, such as necrotizing fasciitis, and rice body formation in atypical mycobacterial tenosynovitis, and bursitis will also be presented

  20. Realistic Material Appearance Modelling

    Czech Academy of Sciences Publication Activity Database

    Haindl, Michal; Filip, Jiří; Hatka, Martin

    2010-01-01

    Roč. 2010, č. 81 (2010), s. 13-14 ISSN 0926-4981 R&D Projects: GA ČR GA102/08/0593 Institutional research plan: CEZ:AV0Z10750506 Keywords : bidirectional texture function * texture modelling Subject RIV: BD - Theory of Information http:// library .utia.cas.cz/separaty/2010/RO/haindl-realistic material appearance modelling.pdf

  1. Color appearance in stereoscopy

    Science.gov (United States)

    Gadia, Davide; Rizzi, Alessandro; Bonanomi, Cristian; Marini, Daniele; Galmonte, Alessandra; Agostini, Tiziano

    2011-03-01

    The relationship between color and lightness appearance and the perception of depth has been studied since a while in the field of perceptual psychology and psycho-physiology. It has been found that depth perception affects the final object color and lightness appearance. In the stereoscopy research field, many studies have been proposed on human physiological effects, considering e.g. geometry, motion sickness, etc., but few has been done considering lightness and color information. Goal of this paper is to realize some preliminar experiments in Virtual Reality in order to determine the effects of depth perception on object color and lightness appearance. We have created a virtual test scene with a simple 3D simultaneous contrast configuration. We have created three different versions of this scene, each with different choices of relative positions and apparent size of the objects. We have collected the perceptual responses of several users after the observation of the test scene in the Virtual Theater of the University of Milan, a VR immersive installation characterized by a semi-cylindrical screen that covers 120° of horizontal field of view from an observation distance of 3.5 m. We present a description of the experiments setup and procedure, and we discuss the obtained results.

  2. Imaging of Composites by Helical X-Ray Computed Tomography

    DEFF Research Database (Denmark)

    Wang, Ying; Pyka, Grzegorz; Jespersen, Kristine Munk

    Understanding the fatigue damage mechanisms of composite materials used in wind turbine rotor blades could potentially enhance the reliability and energy efficiency of wind turbines by improving the structure design. In this paper, the fatigue damage propagating mechanisms of unidirectional glass...... fibre composites was characterised by helical X-ray CT. The staining approach was used and it was effective to enhance the visibility of thin matrix cracks and partly closed fibre breaks instead of widely opened cracks. Fibre breaks in the centre UD bundle were found to occur locally, instead of being...

  3. Generalized helicity and its time derivative

    International Nuclear Information System (INIS)

    Jarboe, T.R.; Marklin, G.J.

    1985-01-01

    Spheromaks can be sustained against resistive decay by helicity injection because they tend to obey the minimum energy principle. This principle states that a plasma-laden magnetic configuration will relax to a state of minimum energy subject to the constraint that the magnetic helicity is conserved. Use of helicity as a constraint on the minimization of energy was first proposed by Woltjer in connection with astrophysical phenomena. Helicity does decay on the resistive diffusion time. However, if helicity is created and made to flow continuoiusly into a confinement geometry, these additional linked fluxes can relax and sustain the configuration indefinitely against the resistive decay. In this paper we will present an extension of the definition of helicity to include systems where B vector can penetrate the boundary and the penetration can be varying in time. We then discuss the sustainment of RFPs and spheromaks in terms of helicity injection

  4. Uterine Leiomyoma: Hysterosalpingographic Appearances

    Directory of Open Access Journals (Sweden)

    Firoozeh Ahmadi

    2008-01-01

    Full Text Available Uterine leiomyoma is the most common benign tumor of genital tract. The etiology of myomasis unknown. Leiomyoma shows a broad spectrum of radiographic appearances depending on thenumber, size, and location of the tumor. The diagnostic method for uterine leiomyomas is basedprimarily on the clinical situation. Despite of the varied diagnostic options such as; transvaginalsonography, sonohysterography, hysteroscopy, laparoscopy and MRI; hysterosalpingography isstill one of the valuable imaging methods for identification of uterine leiomyoma.The various features of the proved leiomyoma are illustrated in this pictorial review. The incidence,risk factors and clinical features will also be discussed briefly.

  5. Wavelet Enhanced Appearance Modelling

    DEFF Research Database (Denmark)

    Stegmann, Mikkel Bille; Forchhammer, Søren; Cootes, Timothy F.

    2004-01-01

    Generative segmentation methods such as the Active Appearance Models (AAM) establish dense correspondences by modelling variation of shape and pixel intensities. Alas, for 3D and high-resolution 2D images typical in medical imaging, this approach is rendered infeasible due to excessive storage......-7 wavelets on face images have shown that segmentation accuracy degrades gracefully with increasing compression ratio. Further, a proposed weighting scheme emphasizing edges was shown to be significantly more accurate at compression ratio 1:1, than a conventional AAM. At higher compression ratios the scheme...

  6. 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)

  7. animal trial on imaging appearances of abdominally retained gauze

    International Nuclear Information System (INIS)

    Wang Longxia; An Ningyu; Yin Hui; Wang Xiangdong; Li Jia; Bai Ying

    2000-01-01

    Objective: To evaluate the imaging appearances of abdominally retained crumpled gauze with US, CT and MRI and the changes with time. Methods: Eight rabbits were operated and crumpled gauze was put into in their abdominal cavity. US , plain and enhanced CT and MRI scan were performed on the day of operation, and 1 to 7 weeks after operation. The imaging appearances were compared with operation findings. Pathologic examination was done simultaneously. Results: Abdominally retained crumpled gauze was instantly adhesive with omentum and neighboring intestines tightly. Fibro-connective tissue membrane was produced at the adhesion site gradually, spreading out to enclose the crumpled gauze. The enclosure was finished completely in 3 to 4 weeks. Thickened membrane also invaded into the spaces within the gauze. The crumpled gauze was eventually infected. These changes could be revealed on US, CT or MRI scans. The US appearance exhibited a hyper echoic arc zone with broad clean acoustic shadow behind. It appeared as a soft tissue mass to CT and MRI scans. In early stage CT scan could easily show the gas within the crumpled gauze. CT and MRI enhanced scans showed only the enhanced membrane and no enhancement of the crumpled gauze. Conclusion: US, CT and MRI have quite characteristic appearances of the abdominally retained crumpled gauze, especially when combined imaging techniques were employed, which can lead to a correct diagnosis together with a history of operation

  8. Helicity formalism and spin effects

    International Nuclear Information System (INIS)

    Anselmino, M.; Caruso, F.; Piovano, U.

    1990-01-01

    The helicity formalism and the technique to compute amplitudes for interaction processes involving leptons, quarks, photons and gluons are reviewed. Explicit calculations and examples of exploitation of symmetry properties are shown. The formalism is then applied to the discussion of several hadronic processes and spin effects: the experimental data, when related to the properties of the elementary constituent interactions, show many not understood features. Also the nucleon spin problem is briefly reviewed. (author)

  9. Radiation characteristics of helical tomotherapy

    International Nuclear Information System (INIS)

    Jeraj, Robert; Mackie, Thomas R.; Balog, John; Olivera, Gustavo; Pearson, Dave; Kapatoes, Jeff; Ruchala, Ken; Reckwerdt, Paul

    2004-01-01

    Helical tomotherapy is a dedicated intensity modulated radiation therapy (IMRT) system with on-board imaging capability (MVCT) and therefore differs from conventional treatment units. Different design goals resulted in some distinctive radiation field characteristics. The most significant differences in the design are the lack of flattening filter, increased shielding of the collimators, treatment and imaging operation modes and narrow fan beam delivery. Radiation characteristics of the helical tomotherapy system, sensitivity studies of various incident electron beam parameters and radiation safety analyses are presented here. It was determined that the photon beam energy spectrum of helical tomotherapy is similar to that of more conventional radiation treatment units. The two operational modes of the system result in different nominal energies of the incident electron beam with approximately 6 MeV and 3.5 MeV in the treatment and imaging modes, respectively. The off-axis mean energy dependence is much lower than in conventional radiotherapy units with less than 5% variation across the field, which is the consequence of the absent flattening filter. For the same reason the transverse profile exhibits the characteristic conical shape resulting in a 2-fold increase of the beam intensity in the center. The radiation leakage outside the field was found to be negligible at less than 0.05% because of the increased shielding of the collimators. At this level the in-field scattering is a dominant source of the radiation outside the field and thus a narrow field treatment does not result in the increased leakage. The sensitivity studies showed increased sensitivity on the incident electron position because of the narrow fan beam delivery and high sensitivity on the incident electron energy, as common to other treatment systems. All in all, it was determined that helical tomotherapy is a system with some unique radiation characteristics, which have been to a large extent

  10. 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.

  11. Three-dimensional image analysis of the skull using variable CT scanning protocols-effect of slice thickness on measurement in the three-dimensional CT images

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Ho Gul; Kim, Kee Deog; Park, Hyok; Kim, Dong Ook; Jeong, Hai Jo; Kim, Hee Joung; Yoo, Sun Kook; Kim, Yong Oock; Park, Chang Seo [Yonsei University College of Medicine, Seoul (Korea, Republic of)

    2004-07-15

    To evaluate the quantitative accuracy of three-dimensional (3D) images by mean of comparing distance measurements on the 3D images with direct measurements of dry human skull according to slice thickness and scanning modes. An observer directly measured the distance of 21 line items between 12 orthodontic landmarks on the skull surface using a digital vernier caliper and each was repeated five times. The dry human skull was scanned with a Helical CT with various slice thickness (3, 5, 7 mm) and acquisition modes (Conventional and Helical). The same observer measured corresponding distance of the same items on reconstructed 3D images with the internal program of V-works 4.0 (Cybermed Inc., Seoul, Korea). The quantitative accuracy of distance measurements were statistically evaluated with Wilcoxons' two-sample test. 11 line items in Conventional 3 mm, 8 in Helical 3 mm, 11 in Conventional 5 mm, 10 in Helical 5 mm, 5 in Conventional 7 mm and 9 in Helical 7 mm showed no statistically significant difference. Average difference between direct measurements and measurements on 3D CT images was within 2 mm in 19 line items of Conventional 3 mm. 20 of Helical 3 mm, 15 of Conventional 5 mm, 18 of Helical 5 mm, 11 of Conventional 7 mm and 16 of Helical 7 mm. Considering image quality and patient's exposure time, scanning protocol of Helical 5 mm is recommended for 3D image analysis of the skull in CT.

  12. Fourier-based approach to interpolation in single-slice helical computed tomography

    International Nuclear Information System (INIS)

    La Riviere, Patrick J.; Pan Xiaochuan

    2001-01-01

    It has recently been shown that longitudinal aliasing can be a significant and detrimental presence in reconstructed single-slice helical computed tomography (CT) volumes. This aliasing arises because the directly measured data in helical CT are generally undersampled by a factor of at least 2 in the longitudinal direction and because the exploitation of the redundancy of fanbeam data acquired over 360 degree sign to generate additional longitudinal samples does not automatically eliminate the aliasing. In this paper we demonstrate that for pitches near 1 or lower, the redundant fanbeam data, when used properly, can provide sufficient information to satisfy a generalized sampling theorem and thus to eliminate aliasing. We develop and evaluate a Fourier-based algorithm, called 180FT, that accomplishes this. As background we present a second Fourier-based approach, called 360FT, that makes use only of the directly measured data. Both Fourier-based approaches exploit the fast Fourier transform and the Fourier shift theorem to generate from the helical projection data a set of fanbeam sinograms corresponding to equispaced transverse slices. Slice-by-slice reconstruction is then performed by use of two-dimensional fanbeam algorithms. The proposed approaches are compared to their counterparts based on the use of linear interpolation - the 360LI and 180LI approaches. The aliasing suppression property of the 180FT approach is a clear advantage of the approach and represents a step toward the desirable goal of achieving uniform longitudinal resolution properties in reconstructed helical CT volumes

  13. Magnetic helicity and active filament configuration

    Science.gov (United States)

    Romano, P.; Zuccarello, F.; Poedts, S.; Soenen, A.; Zuccarello, F. P.

    2009-11-01

    Context: The role of magnetic helicity in active filament formation and destabilization is still under debate. Aims: Although active filaments usually show a sigmoid shape and a twisted configuration before and during their eruption, it is unclear which mechanism leads to these topologies. In order to provide an observational contribution to clarify these issues, we describe a filament evolution whose characteristics seem to be directly linked to the magnetic helicity transport in corona. Methods: We applied different methods to determine the helicity sign and the chirality of the filament magnetic field. We also computed the magnetic helicity transport rate at the filament footpoints. Results: All the observational signatures provided information on the positive helicity and sinistral chirality of the flux rope containing the filament material: its forward S shape, the orientation of its barbs, the bright and dark threads at 195 Å. Moreover, the magnetic helicity transport rate at the filament footpoints showed a clear accumulation of positive helicity. Conclusions: The study of this event showed a correspondence between several signatures of the sinistral chirality of the filament and several evidences of the positive magnetic helicity of the filament magnetic field. We also found that the magnetic helicity transported along the filament footpoints showed an increase just before the change of the filament shape observed in Hα images. We argued that the photospheric regions where the filament was rooted might be the preferential ways where the magnetic helicity was injected along the filament itself and where the conditions to trigger the eruption were yielded.

  14. Saliency Changes Appearance

    Science.gov (United States)

    Kerzel, Dirk; Schönhammer, Josef; Burra, Nicolas; Born, Sabine; Souto, David

    2011-01-01

    Numerous studies have suggested that the deployment of attention is linked to saliency. In contrast, very little is known about how salient objects are perceived. To probe the perception of salient elements, observers compared two horizontally aligned stimuli in an array of eight elements. One of them was salient because of its orientation or direction of motion. We observed that the perceived luminance contrast or color saturation of the salient element increased: the salient stimulus looked even more salient. We explored the possibility that changes in appearance were caused by attention. We chose an event-related potential indexing attentional selection, the N2pc, to answer this question. The absence of an N2pc to the salient object provides preliminary evidence against involuntary attentional capture by the salient element. We suggest that signals from a master saliency map flow back into individual feature maps. These signals boost the perceived feature contrast of salient objects, even on perceptual dimensions different from the one that initially defined saliency. PMID:22162760

  15. New formulae for magnetic relative helicity and field line helicity

    Science.gov (United States)

    Aly, Jean-Jacques

    2018-01-01

    We consider a magnetic field {B} occupying the simply connected domain D and having all its field lines tied to the boundary S of D. We assume here that {B} has a simple topology, i.e., the mapping {M} from positive to negative polarity areas of S associating to each other the two footpoints of any magnetic line, is continuous. We first present new formulae for the helicity H of {B} relative to a reference field {{B}}r having the same normal component {B}n on S, and for its field line helicity h relative to a reference vector potential {{C}}r of {{B}}r. These formulae make immediately apparent the well known invariance of these quantities under all the ideal MHD deformations that preserve the positions of the footpoints on S. They express indeed h and H either in terms of {M} and {B}n, or in terms of the values on S of a pair of Euler potentials of {B}. We next show that, for a specific choice of {{C}}r, the field line helicity h of {B} fully characterizes the magnetic mapping {M} and then the topology of the lines. Finally, we give a formula that describes the rate of change of h in a situation where the plasma moves on the perfectly conducting boundary S without changing {B}n and/or non-ideal processes, described by an unspecified term {N} in Ohm’s law, are at work in some parts of D.

  16. CT appearance of acute inflammatory disease of the renal interstitium

    International Nuclear Information System (INIS)

    Gold, R.P.; McClennan, B.L.; Rottenberg, R.R.

    1983-01-01

    Today, infection remains the most common disease of the urinary tract and constitutes almost 75% of patient problems requiring urologic evaluation. There have been several major factors responsible for our better understanding of the nature and pathophysiology of urinary tract infection. One has been quantitated urine bacteriology and another, the discovery that a significant part of the apparently healthy adult female population has asymptomatic bacteriuria. Abnormal conditions such as neurogenic bladder, bladder malignancy, prolonged catheter drainage and reflux, altered host resistance, diabetes mellitus, and urinary tract obstruction, as well as pregnancy, may either predispose to or be implicated in the pathogenesis of urinary tract infection. There is a wide range of conditions that result in acute renal inflammation and those under discussion affect primarily the interstitium. This term refers to the connective tissue elements separating the tubules in the cortex and medulla. Hence, the interstitial nephritides are to be distinguished from the glomerulonephritides and fall into two general etiologic categories: infectious and noninfectious

  17. Spontaneous intramural haematoma of the oesophagus: CT and MRI appearances

    Energy Technology Data Exchange (ETDEWEB)

    Yuen, E.H.Y.; Yang, W.T.; Lam, W.W.M.; Kew, J.; Metreweli, C. [Prince of Wales Hospital, Shatin, New Territories (Hong Kong). Department of Diagnostic Radiology and Organ Imaging

    1998-05-01

    A 64-year-old man with history of ischaemic heart disease and coronary artery bypass graft surgery, but no history o peptic ulcer or liver disease, presented with retrosternal pain and coffee-ground vomitus. Endoscopy revealed a lone column of bluish discolouration with normal mucosa interpreted as a grade IV oesophageal varix. Computed tomography showed a non-enhancing low-density submucosal columnar lesion in the mid- and lower oesophagus consistent with a submucosal haematoma. This resolved on follow-up at 10 days. The magnetic resonance features o intermediate signal intensity on T1 -weighted images and hyperintense signal on T2-weighted images of this lesion are also highlighted. Copyright (1998) Blackwell Science Pty Ltd 11 refs., 3 figs.

  18. Spontaneous intramural haematoma of the oesophagus: CT and MRI appearances

    International Nuclear Information System (INIS)

    Yuen, E.H.Y.; Yang, W.T.; Lam, W.W.M.; Kew, J.; Metreweli, C.

    1998-01-01

    A 64-year-old man with history of ischaemic heart disease and coronary artery bypass graft surgery, but no history o peptic ulcer or liver disease, presented with retrosternal pain and coffee-ground vomitus. Endoscopy revealed a lone column of bluish discolouration with normal mucosa interpreted as a grade IV oesophageal varix. Computed tomography showed a non-enhancing low-density submucosal columnar lesion in the mid- and lower oesophagus consistent with a submucosal haematoma. This resolved on follow-up at 10 days. The magnetic resonance features o intermediate signal intensity on T1 -weighted images and hyperintense signal on T2-weighted images of this lesion are also highlighted. Copyright (1998) Blackwell Science Pty Ltd

  19. Motion estimation and compensation in dynamic spiral CT reconstruction

    International Nuclear Information System (INIS)

    Kimdon, J.; Grangeat, P.; Koenig, A.; Bonnet, St.

    2004-01-01

    Respiratory and cardiac motion causes blurring in dynamic X-ray Computed Tomography (CT). Fast scans reduce this problem, but they require a higher radiation dose per time period to maintain the signal to noise ratio of the resulting images, thereby magnifying the health risk to the patient. As an alternative to increased radiation, our team has already developed a cone-beam reconstruction algorithm based on a dynamic particle model that estimates, predicts, and compensates for respiratory motion in circular X-ray CT. The current paper presents an extension of this method to spiral CT, applicable to modern multi-slice scanners that take advantage of the speed and dose benefits of helical trajectories. We adapted all three main areas of the algorithm: backprojection, prediction, and compensation/accumulation. In backprojection, we changed the longitudinal re-binning technique, filter direction, and the method of enforcing the data sufficiency requirements. For prediction, we had to be careful of objects appearing and disappearing as the scanner bed advanced. For compensation/accumulation, we controlled the reconstruction time and combined images to cover a greater longitudinal extent for each phase in the respiratory or cardiac cycle. Tests with moving numerical phantoms demonstrate that the algorithm successfully improves the temporal resolution of the images without increasing the dose or reducing the signal-to-noise ratio. (authors)

  20. Postnatal development of the anterior skull base and nasal septum: CT study

    International Nuclear Information System (INIS)

    Kim, Kwan Soo; Kim, Hyung Jin; Lee, Kyung Hee; Roh, Hong Gee; Lim, Myung Kwan

    2002-01-01

    To know the normal CT appearance of the anterior skull base and nasal septum after birth. Coronal CT scans with a helical mode were performed from the nasal bone to the sphenoid sinus in 99 children whose ages ranged from 27 days to 14 years. We investigated the CT appearance of the developing anterior skull base and nasal septum with particular attention to the anteroposterior length of the anterior skull base and the ossification patterns of the cribriform plate, perpendicular plate, crista galli, and vomer. The anteroposterior length of the anterior skull base statistically significantly increased with age. The cribriform plate showed partial or complete ossification in at least one segment at more than 3 months of age and in all three segments at more than 6 months of age. Ossification of the cribriform plate occurred earlier in the middle segment than in the anterior and posterior segments. It began exclusively in the region of the lateral mass of the ethmoid and proceeded medially toward the crista galli. Partial ossification of the perpendicular plate was noted as early as 9 months of age, and complete ossification as early as 13 months of age. All children at 18 months and older showed at least partial ossification of the perpendicular plate. Partial ossification of the crista galli was noted as early as 27 days of age, and complete ossification as early as 3 months of age. CT showed complete ossification of the crista galli in all but two children at 6 months and older. The superior aspect of the vomer exhibited a V- or Y-shape on all CT scans in 66%(65/99) of children at any age. It appeared as an undivided single lump anteriorly and a V or Y posteriorly in 34%(34/99). Knowledge of the normal developing patterns of ossification of the anterior skull base and nasal septum could help prevent errors in interpreting CT scans in this region, especially in infants and young children

  1. MHD stability analysis of helical system plasmas

    International Nuclear Information System (INIS)

    Nakamura, Yuji

    2000-01-01

    Several topics of the MHD stability studies in helical system plasmas are reviewed with respect to the linear and ideal modes mainly. Difference of the method of the MHD stability analysis in helical system plasmas from that in tokamak plasmas is emphasized. Lack of the cyclic (symmetric) coordinate makes an analysis more difficult. Recent topic about TAE modes in a helical system is also described briefly. (author)

  2. Employing helicity amplitudes for resummation in SCET

    International Nuclear Information System (INIS)

    Moult, Ian; Stewart, Iain W.; Tackmann, Frank J.; Waalewijn, Wouter J.; Nikhef, Amsterdam

    2016-05-01

    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.

  3. CT colonoscopy: sensibility in 2D/4D CT colonoscopy versus virtual endoscopy. Correlation to conventional colonoscopy

    International Nuclear Information System (INIS)

    Carrascosa, Patricia; Capunay, Carlos; Sanchez, Flavio; Castiglioni, Roberto; Carrascosa, Jorge

    2001-01-01

    Colorectal carcinoma is the second leading cause of death from malignant tumors. Most large bowel malignancies arise from pre-existing adenomas. In individual older than 50 years the prevalence of polyps and cancer increases. Therefore screening is recommended for average risk individuals in this group. Recently a new technique called 'Virtual Colonoscopy' has appeared. The purpose of this study was to compare the diagnosis accuracy of two dimensional CT Colonoscopy (2D CTC) and Virtual Colonoscopy (VC) individually with Conventional Colonoscopy (CC) and to determine improvement of the Sensitivity (S) and Specificity (E) combining both types of evaluation. Ninety patients were studied (47 women and 43 men). CT studies were obtained on a helical CT scanner. The lesions were studied in supine and prone position. All patients had CC done within 10 hours before CTC. The lesions were divided in 3 groups: 1) 9 mm. Each group was divided into 3 subgroups: a) findings in 2D; b) findings in VC; and c) findings combined. Ninety-two lesions were identified on CC and 101 on CTC. There were 9 false positive in all groups. The statistical analysis showed a high S and E in both 2D and VC. The combination of both methods does not increase significantly the diagnosis of CTC but the S reached 100% because the false negative rate was reduced to 0. (author)

  4. Cardiac cone-beam CT

    International Nuclear Information System (INIS)

    Manzke, Robert

    2005-01-01

    This doctoral thesis addresses imaging of the heart with retrospectively gated helical cone-beam computed tomography (CT). A thorough review of the CT reconstruction literature is presented in combination with a historic overview of cardiac CT imaging and a brief introduction to other cardiac imaging modalities. The thesis includes a comprehensive chapter about the theory of CT reconstruction, familiarizing the reader with the problem of cone-beam reconstruction. The anatomic and dynamic properties of the heart are outlined and techniques to derive the gating information are reviewed. With the extended cardiac reconstruction (ECR) framework, a new approach is presented for the heart-rate-adaptive gated helical cardiac cone-beam CT reconstruction. Reconstruction assessment criteria such as the temporal resolution, the homogeneity in terms of the cardiac phase, and the smoothness at cycle-to-cycle transitions are developed. Several reconstruction optimization approaches are described: An approach for the heart-rate-adaptive optimization of the temporal resolution is presented. Streak artifacts at cycle-to-cycle transitions can be minimized by using an improved cardiac weighting scheme. The optimal quiescent cardiac phase for the reconstruction can be determined automatically with the motion map technique. Results for all optimization procedures applied to ECR are presented and discussed based on patient and phantom data. The ECR algorithm is analyzed for larger detector arrays of future cone-beam systems throughout an extensive simulation study based on a four-dimensional cardiac CT phantom. The results of the scientific work are summarized and an outlook proposing future directions is given. The presented thesis is available for public download at www.cardiac-ct.net

  5. On the diffusion of alpha-helical proteins in solvents

    Science.gov (United States)

    Barredo, Wilson I.; Bornales, Jinky B.; Bernido, Christopher C.; Aringa, Henry P.

    2015-01-01

    The winding probability function for a biopolymer diffusing in a crowded cell is obtained with the drift coefficient f(s) involving Bessel functions of general form f(s) = kJ2p+1 (νs). The variable s is the length along the chain and ν is a constant which can be used to simulate the frequency of appearance of a certain type of amino acid. Application of a particular case p = 3 to protein chains is carried out for different alpha helical proteins found in the Protein Data Bank (PDB). Analysis of our results leads us to an empirical formula that can be used to conveniently predict k/D and ν, where D is the diffusion coefficient of various α-helical proteins in solvents.

  6. Computed tomographic appearance of resectable pancreatic carcinoma

    International Nuclear Information System (INIS)

    Itai, Y.; Araki, T.; Tasaka, A.; Maruyama, M.

    1982-01-01

    Thirteen patients with resectable pancreatic carcinoma were examined by computed tomography (CT). Nine had a mass, 2 had dilatation of the main pancreatic duct, 1 appeared to have ductal dilatation, and 1 had no sign of abnormality. Resectable carcinoma was diagnosed retrospectively in 8 cases, based on the following criteria: a mass with a distinct contour, frequently containing a tiny or irregular low-density area and accompanied by dilatation of the caudal portion of the main pancreatic duct without involvement of the large vessels, liver, or lymph nodes. Including unresectable cancer, chronic pancreatitis, and obstructive jaundice from causes other than cancer, the false-positive rate was less than 6%. However, a small cancer without change in pancreatic contour is difficult to detect with CT

  7. CT of laryngeal trauma

    International Nuclear Information System (INIS)

    Jeffrey, R.B.

    1986-01-01

    Computed tomography has made a significant contribution to the radiologic assessment of the injured larynx. CT is an accurate, noninvasive modality that can rapidly diagnose both soft tissue and cartilaginous injuries. CT of the larynx involves a minimal degree of patient manipulation and discomfort and can be performed in conjunction with CT evaluation of intracranial or facial injuries. Conventional radiologic studies (anteroposterior and lateral soft tissue films of the neck, tomograms, or xerograms) are capable of demonstrating some cartilaginous fractures but are of limited value in defining the extent of soft tissue injury. In the acute trauma setting, laryngography is often technically difficult to perform because of patient discomfort and inability to cooperate. Although the overall experience is somewhat limited, CT appears to overcome many of the limitations of these conventional radiologic methods. The following is a discussion of the role of CT scanning in evaluating injuries to the larynx and cervical soft tissues

  8. Comparison of excretory phase, helical computed tomography with intravenous urography in patients with painless haematuria

    International Nuclear Information System (INIS)

    O'Malley, M.E.; Hahn, P.F.; Yoder, I.C.; Gazelle, G.S.; McGovern, F.J.; Mueller, P.R.

    2003-01-01

    AIM: To compare excretory phase, helical computed tomography (CT) with intravenous (IV) urography for evaluation of the urinary tract in patients with painless haematuria. MATERIALS AND METHODS: Ninety-one out-patients had IV urography followed by helical CT limited to the urinary tract. Both IV urograms and CT images were evaluated for abnormalities of the urinary tract in a blinded, prospective manner. The clinical significance of abnormalities was scored subjectively and receiver operator characteristic curve analysis was performed. RESULTS: In 69 of 91 patients (76%), no cause of haematuria was identified. In 22 of 91 patients (24%), the cause of haematuria was identified as follows: transitional cell cancer of the bladder (n=15), urinary tract stones (n=3), cystitis (n=2), haemorrhagic pyelitis (n=1) and benign ureteral stricture (n=1). With IV urography, there were 15 true-positive, seven false-negative and three false-positive interpretations. With CT, there were 18 true-positive, four false-negative and two false-positive interpretations. There was no significant difference between IV and CT urography for the significance of the positive interpretations (n=0.47). CONCLUSION: Excretory phase CT urography was comparable with IV urography for evaluation of the urinary tract in patients with painless haematuria. However, the study population did not include any upper tract cancers. O'Malley M. E. et al. (2003). Clinical Radiology 58, 294-300

  9. CT of chest trauma

    International Nuclear Information System (INIS)

    Goodman, P.C.

    1986-01-01

    There appears to be a limited role for computed tomography in the evaluation of chest trauma. The literature contains few papers specifically addressing the use of CT in the setting of chest trauma. Another series of articles relates anecdotal experiences in this regard. This paucity of reports attests to the remarkable amount of information present on conventional chest radiographs as well as the lack of clear indications for CT in the setting of chest trauma. In this chapter traumatic lesions of various areas of the thorax are discussed. The conventional radiographic findings are briefly described and the potential or proven application of CT is addressed

  10. MR appearance of hypothalamic hamartoma

    Energy Technology Data Exchange (ETDEWEB)

    Hahn, F.J.; Leibrock, L.G.; Huseman, C.A.; Makos, M.M.

    1988-02-01

    Hypothalamic hamartoma is the most common detectable cerebral lesion causing precocious puberty. Two histologically confirmed cases were studied by computerized tomography (CT) and magnetic resonance (MR) imaging. T2 weighted, sagittal MR images were superior to CT in delineating the tumor from surrounding grey matter. The lesion was isointense to grey matter on T1 weighted images allowing exclusion of other hypothalamic tumors. MR will undoubtedly become the imaging modality of choice in the detection of hypothalamic hamartoma.

  11. Computed tomographic appearances of cherubism

    Energy Technology Data Exchange (ETDEWEB)

    Bianchi, S D; Boccardi, A; Mela, F; Romagnoli, R

    1987-01-01

    The computed tomographic (CT) aspects of six cases of cherubism are described. Through its optimal representation of the lesions, CT enabled certain characteristics of this disease to be substantiated, namely, limitation of the process to the bones of the jaw and primarily superficial development of the mandibular lesions, coupled with an unusual mandibular condylar impairment. Moreover, the composition of this series permitted investigation of the condition in its several stages of progression.

  12. Beta-helical polymers from isocyanopeptides

    NARCIS (Netherlands)

    Cornelissen, J.J.L.M.; Donners, J.J.J.M.; Gelder, de R.; Graswinckel, W.S.; Metselaar, G.A.; Rowan, A.E.; Sommerdijk, N.A.J.M.; Nolte, R.J.M.

    2001-01-01

    Polymerization of isocyanopeptides results in the formation of high molecular mass polymers that fold in a proteinlike fashion to give helical strands in which the peptide chains are arranged in ß-sheets. The ß-helical polymers retain their structure in water and unfold in a cooperative process at

  13. Magnetic islands created by resonant helical windings

    International Nuclear Information System (INIS)

    Fernandes, A.S.; Heller, M.V.; Caldas, I.L.

    1986-01-01

    The triggering of disruptive instabilities by resonant helical windings in large aspect-ratio tokamaks is associated to destruction of magnetic surfaces. The Chirikov condition is applied to estimate analytically the helical winding current thresholds for ergodization of the magnetic field lines. (Autor) [pt

  14. Helicity amplitudes for matter-coupled gravity

    International Nuclear Information System (INIS)

    Aldrovandi, R.; Novaes, S.F.; Spehler, D.

    1992-07-01

    The Weyl-van der Waerden spinor formalism is applied to the evaluation of helicity invariant amplitudes in the framework of linearized gravitation. The graviton couplings to spin-0, 1 - 2 , 1, and 3 - 2 particles are given, and, to exhibit the reach of this method, the helicity amplitudes for the process electron + positron → photon + graviton are obtained. (author)

  15. Stiffness versus architecture of single helical polyisocyanopeptides

    NARCIS (Netherlands)

    Buul, van A.M.; Schwartz, E.; Brocorens, P.; Koepf, M.; Beljonne, D.; Maan, J.C.; Christianen, P.C.M.; Kouwer, P.H.J.; Nolte, R.J.M.; Engelkamp, H.; Blank, K.; Rowan, A.E.

    2013-01-01

    Helical structures play a vital role in nature, offering mechanical rigidity, chirality and structural definition to biological systems. Little is known about the influence of the helical architecture on the intrinsic properties of polymers. Here, we offer an insight into the nano architecture of

  16. Dynamics of zonal flows in helical systems.

    Science.gov (United States)

    Sugama, H; Watanabe, T-H

    2005-03-25

    A theory for describing collisionless long-time behavior of zonal flows in helical systems is presented and its validity is verified by gyrokinetic-Vlasov simulation. It is shown that, under the influence of particles trapped in helical ripples, the response of zonal flows to a given source becomes weaker for lower radial wave numbers and deeper helical ripples while a high-level zonal-flow response, which is not affected by helical-ripple-trapped particles, can be maintained for a longer time by reducing their bounce-averaged radial drift velocity. This implies a possibility that helical configurations optimized for reducing neoclassical ripple transport can simultaneously enhance zonal flows which lower anomalous transport.

  17. A morphological study of the mandibular molar region using reconstructed helical computed tomographic images

    International Nuclear Information System (INIS)

    Tsuno, Hiroaki; Noguchi, Makoto; Noguchi, Akira; Yoshida, Keiko; Tachinami, Yasuharu

    2010-01-01

    This study investigated the morphological variance in the mandibular molar region using reconstructed helical computed tomographic (CT) images. In addition, we discuss the necessity of CT scanning as part of the preoperative assessment process for dental implantation, by comparing the results with the findings of panoramic radiography. Sixty patients examined using CT as part of the preoperative assessment for dental implantation were analyzed. Reconstructed CT images were used to evaluate the bone quality and cross-sectional bone morphology of the mandibular molar region. The mandibular cortical index (MCI) and X-ray density ratio of this region were assessed using panoramic radiography in order to analyze the correlation between the findings of the CT images and panoramic radiography. CT images showed that there was a decrease in bone quality in cases with high MCI. Cross-sectional CT images revealed that the undercuts on the lingual side in the highly radiolucent areas in the basal portion were more frequent than those in the alveolar portion. This study showed that three-dimensional reconstructed CT images can help to detect variances in mandibular morphology that might be missed by panoramic radiography. In conclusion, it is suggested that CT should be included as an important examination tool before dental implantation. (author)

  18. Topology of helical fluid flow

    DEFF Research Database (Denmark)

    Andersen, Morten; Brøns, Morten

    2014-01-01

    function for the topology of the streamline pattern in incompressible flows. On this basis, we perform a comprehensive study of the topology of the flow field generated by a helical vortex filament in an ideal fluid. The classical expression for the stream function obtained by Hardin (Hardin, J. C. 1982...... the zeroes of a single real function of one variable, and we show that three different flow topologies can occur, depending on a single dimensionless parameter. By including the self-induced velocity on the vortex filament by a localised induction approximation, the stream function is slightly modified...... and an extra parameter is introduced. In this setting two new flow topologies arise, but not more than two critical points occur for any combination of parameters....

  19. Helically coiled tube heat exchanger

    International Nuclear Information System (INIS)

    Harris, A.M.

    1981-01-01

    In a heat exchanger such as a steam generator for a nuclear reactor, two or more bundles of helically coiled tubes are arranged in series with the tubes in each bundle integrally continuing through the tube bundles arranged in series therewith. Pitch values for the tubing in any pair of tube bundles, taken transverse to the path of the reactor coolant flow about the tubes, are selected as a ratio of two unequal integers to permit efficient operation of each tube bundle while maintaining the various tube bundles of the heat exchanger within a compact envelope. Preferably, the helix angle and tube pitch parallel to the path of coolant flow are constant for all tubes in a single bundle so that the tubes are of approximately the same length within each bundle

  20. The quantum Hall effect helicity

    Energy Technology Data Exchange (ETDEWEB)

    Shrivastava, Keshav N., E-mail: keshav1001@yahoo.com [Department of Physics, University of Malaya, Kuala Lumpur 50603 (Malaysia); School of Physics, University of Hyderabad, Hyderabad 500046 (India)

    2015-04-16

    The quantum Hall effect in semiconductor heterostructures is explained by two signs in the angular momentum j=l±s and g=(2j+1)/(2l+1) along with the Landau factor (n+1/2). These modifications in the existing theories explain all of the fractional charges. The helicity which is the sign of the product of the linear momentum with the spin p.s plays an important role for the understanding of the data at high magnetic fields. In particular it is found that particles with positive sign in the spin move in one direction and those with negative sign move in another direction which explains the up and down stream motion of the particles.

  1. Influence of gantry angle in helical computed tomography. Usefullness of 1-dimension sharpness filter

    Energy Technology Data Exchange (ETDEWEB)

    Kawano, Hirofumi; Suzuki, Toru; Matsuura, Shigeru; Kai, Tsuyoshi; Shimizu, Toshiyuki [Hyuga Hospital of Saiseikai Foundation, Kadogawa, Miyazaki (Japan)

    2001-05-01

    When we let gantry tilt and do scan in helical CT, vertical sharpness deteriorates. We were able to revise it with 1-dimensional sharpness filter which the square sum of difference of MTF was compared, and was designed this time. And the unsharpness was in proportion to sin of gantry angle. As a result, we led several sets of frequency emphasis degree. There is a model to built 1-dimension sharpness filter in a scan plan. It is useful for clinical diagnoses. (author)

  2. Influence of gantry angle in helical computed tomography. Usefullness of 1-dimension sharpness filter

    International Nuclear Information System (INIS)

    Kawano, Hirofumi; Suzuki, Toru; Matsuura, Shigeru; Kai, Tsuyoshi; Shimizu, Toshiyuki

    2001-01-01

    When we let gantry tilt and do scan in helical CT, vertical sharpness deteriorates. We were able to revise it with 1-dimensional sharpness filter which the square sum of difference of MTF was compared, and was designed this time. And the unsharpness was in proportion to sin of gantry angle. As a result, we led several sets of frequency emphasis degree. There is a model to built 1-dimension sharpness filter in a scan plan. It is useful for clinical diagnoses. (author)

  3. The Great Solar Active Region NOAA 12192: Helicity Transport, Filament Formation, and Impact on the Polar Field

    Science.gov (United States)

    Petrie, Gordon; McMaken, Tyler C.

    2017-08-01

    The solar active region (AR), NOAA 12192, appeared in 2014 October as the largest AR in 24 years. Here we examine the counterintuitive nature of two diffusion-driven processes in the region: the role of helicity buildup in the formation of a major filament, and the relationship between the effects of supergranular diffusion and meridional flow on the AR and on the polar field. Quantitatively, calculations of current helicity and magnetic twist from Helioseismic and Magnetic Imager (HMI) vector magnetograms indicate that, though AR 12192 emerged with negative helicity, positive helicity from subsequent flux emergence, consistent with the hemispheric sign-preference of helicity, increased over time within large-scale, weak-field regions such as those near the polarity inversion line (PIL). Morphologically, Atmospheric Imaging Assembly observations of filament barbs, sigmoidal patterns, and bases of Fe xii stalks initially exhibited signatures of negative helicity, and the long filament that subsequently formed had a strong positive helicity consistent with the helicity buildup along the PIL. We find from full-disk HMI magnetograms that AR 12192's leading positive flux was initially closer to the equator but, owing either to the region’s magnetic surroundings or to its asymmetric flux density distribution, was transported poleward more quickly on average than its trailing negative flux, contrary to the canonical pattern of bipole flux transport. This behavior caused the AR to have a smaller effect on the polar fields than expected and enabled the formation of the very long neutral line where the filament formed.

  4. Computed tomographic appearance of mucormycosis

    International Nuclear Information System (INIS)

    Vogl, T.J.; Hinrichs, T.; Jacobi, V.; Boehme, A.; Hoelzer, D.

    2000-01-01

    Aim: Analysis of the morphological characteristics of pulmonary mucormycosis using computed tomography (CT). Material and methods: Prospective analysis of CT studies in 9 patients out of 19 patients with proven pulmonary mucormycosis. Results: Pulmonary mucormycosis was most frequently found in the upper lobe bilaterally (51% of all nodules). In 22% of the manifestations, the morphological criterion of a 'bird's nest' could be verified in CT, in 37% central necrotic areas were detected. In 37% an open bronchus was diagnosed, in 6% we observed bronchiectases. 43% of all nodules presented with a halo sign. In three patients we found pleural effusions, enlarged mediastinal lymph nodes were diagnosed in one patient. Conclusion: Computed tomography allows an improved diagnosis and therapeutic follow-up in patients suffering from pulmonary mucormycosis. (orig.) [de

  5. HEMISPHERIC HELICITY TREND FOR SOLAR CYCLE 24

    International Nuclear Information System (INIS)

    Hao Juan; Zhang Mei

    2011-01-01

    Using vector magnetograms obtained with the Spectro-polarimeter (SP) on board Hinode satellite, we studied two helicity parameters (local twist and current helicity) of 64 active regions that occurred in the descending phase of solar cycle 23 and the ascending phase of solar cycle 24. Our analysis gives the following results. (1) The 34 active regions of the solar cycle 24 follow the so-called hemispheric helicity rule, whereas the 30 active regions of the solar cycle 23 do not. (2) When combining all 64 active regions as one sample, they follow the hemispheric helicity sign rule as in most other observations. (3) Despite the so-far most accurate measurement of vector magnetic field given by SP/Hinode, the rule is still weak with large scatters. (4) The data show evidence of different helicity signs between strong and weak fields, confirming previous result from a large sample of ground-based observations. (5) With two example sunspots we show that the helicity parameters change sign from the inner umbra to the outer penumbra, where the sign of penumbra agrees with the sign of the active region as a whole. From these results, we speculate that both the Σ-effect (turbulent convection) and the dynamo have contributed in the generation of helicity, whereas in both cases turbulence in the convection zone has played a significant role.

  6. Standardized CT examination of the multitraumatized patient

    Energy Technology Data Exchange (ETDEWEB)

    Leidner, B. [Department of Diagnostic Radiology, Oskarshamn Hospital (Sweden)]|[Department of Diagnostic Radiology, Huddinge University Hospital (Sweden); Adiels, M. [Department of Diagnostic Radiology, Oskarshamn Hospital (Sweden); Aspelin, P. [Department of Diagnostic Radiology, Huddinge University Hospital (Sweden); Gullstrand, P.; Wallen, S. [Department of Surgery, Oskarshamn Hospital (Sweden)

    1998-12-01

    The aim of this study was to develop a standardized non-helical-CT protocol including head, body and proximal extremities in order to achieve a good time efficiency and diagnostic accuracy in the initial radiological evaluation of the multitraumatized patient. A total of 111 circulatory stable blunt trauma patients, brought in to a trauma level II-III hospital, were examined according to a standardized CT protocol. After examining the head with contiguous 10-mm slices without IV contrast medium injection, the trunk was examined with 10-mm slices every 30 mm through thorax-abdomen-pelvis with IV contrast medium enhancement (occasionally modified). All data in the medical reports were collected and used as ``end-point``, and the outcome of the CT examination was compared with this final diagnosis. Mean examination time was 20 min (range 12-32 min). In total, 55 head injuries, 89 thoracic injuries, 27 abdominal/pelvic injuries and 62 fractures were found. Computed tomography correctly identified the injuries, except one brain stem injury, one contusion/rupture of the heart, one hepatic injury, two intestinal injuries, eight vertebral injuries and one joint dislocation. A standardized non-helical-CT examination of the head and body may be achieved in 20 min. Its diagnostic accuracy was high, except for vertebral column injuries, which is why we recommend it as the method of choice for initial radiological examination of multitraumatized patients. When available, helical scanning would improve both examination speed and accuracy. (orig.) With 6 figs., 40 refs.

  7. A theoretically exact reconstruction algorithm for helical cone-beam differential phase-contrast computed tomography

    International Nuclear Information System (INIS)

    Li Jing; Sun Yi; Zhu Peiping

    2013-01-01

    Differential phase-contrast computed tomography (DPC-CT) reconstruction problems are usually solved by using parallel-, fan- or cone-beam algorithms. For rod-shaped objects, the x-ray beams cannot recover all the slices of the sample at the same time. Thus, if a rod-shaped sample is required to be reconstructed by the above algorithms, one should alternately perform translation and rotation on this sample, which leads to lower efficiency. The helical cone-beam CT may significantly improve scanning efficiency for rod-shaped objects over other algorithms. In this paper, we propose a theoretically exact filter-backprojection algorithm for helical cone-beam DPC-CT, which can be applied to reconstruct the refractive index decrement distribution of the samples directly from two-dimensional differential phase-contrast images. Numerical simulations are conducted to verify the proposed algorithm. Our work provides a potential solution for inspecting the rod-shaped samples using DPC-CT, which may be applicable with the evolution of DPC-CT equipments. (paper)

  8. Polymorphic transformation of helical flagella of bacteria

    Science.gov (United States)

    Lim, Sookkyung; Howard Berg Collaboration; William Ko Collaboration; Yongsam Kim Collaboration; Wanho Lee Collaboration; Charles Peskin Collaboration

    2016-11-01

    Bacteria such as E. coli swim in an aqueous environment by utilizing the rotation of flagellar motors and alternate two modes of motility, runs and tumbles. Runs are steady forward swimming driven by bundles of flagellar filaments whose motors are turning CCW; tumbles involve a reorientation of the direction of swimming triggered by motor reversals. During tumbling, the helical flagellum undergoes polymorphic transformations, which is a local change in helical pitch, helical radius, and handedness. In this work, we investigate the underlying mechanism of structural conformation and how this polymorphic transition plays a role in bacterial swimming. National Science Foundation.

  9. Modelling simple helically delivered dose distributions

    International Nuclear Information System (INIS)

    Fenwick, John D; Tome, Wolfgang A; Kissick, Michael W; Mackie, T Rock

    2005-01-01

    In a previous paper, we described quality assurance procedures for Hi-Art helical tomotherapy machines. Here, we develop further some ideas discussed briefly in that paper. Simple helically generated dose distributions are modelled, and relationships between these dose distributions and underlying characteristics of Hi-Art treatment systems are elucidated. In particular, we describe the dependence of dose levels along the central axis of a cylinder aligned coaxially with a Hi-Art machine on fan beam width, couch velocity and helical delivery lengths. The impact on these dose levels of angular variations in gantry speed or output per linear accelerator pulse is also explored

  10. Permeation Barrier Coatings for the Helical Heat Exchanger

    International Nuclear Information System (INIS)

    Korinko, P.S.

    1999-01-01

    A permeation barrier coating was specified for the Helical Heat Exchanger (HHE) to minimize contamination through emissions and/or permeation into the nitrogen system for ALARA reasons. Due to the geometry of the HHE, a special coating practice was needed since the conventional method of high temperature pack aluminization was intractable. A survey of many coating companies was undertaken; their coating capabilities and technologies were assessed and compared to WSRC needs. The processes and limitations to coating the HHE are described. Slurry coating appears to be the most technically sound approach for coating the HHE

  11. Intrahepatic cholangiocarcinoma : gross appearance and corresponding pathologic and radiologic features

    International Nuclear Information System (INIS)

    Yoon, Kwon Ha; Kim, Chang Guhn; Lee, Moon Gyu; Ha, Hyun Kwon; Auh, Yong Ho; Lim, Jae Hoon

    1999-01-01

    To assess the clinical and pathologic features of each type of intrahepatic cholangiocarcinoma, which is divided into three types according to gross appearance, and to determine the efficacy of CT in detecting this tumor. The pathologic and CT features of 53 surgically proven cases of intrahepatic cholangio-carcinoma were reviewed. On the basis of their gross appearance, the tumors were divided into three types, as follows : mass forming (n=33), periductal infiltrating (n=6), and intraductal growth type (n=14). CT scans were analyzed for sensitivity of detection and correlation between a tumors appearance and its histopathology. The most common histopathologic feature of mass forming and periductal infiltrating type was tubular adenocarcinoma, while in the intraductal growth type, papillary adenocarcinoma (100%) was common. With regard to pattern of tumor spread, intrahepatic and lymph node metastasis were more common in the mass forming and periductal infiltrating type than in the intraductal growth type. CT findings including intrahepatic mass, ductal wall thickening or intraductal mass associated with segmental dilatation of intrahepataic bile ducts, corresponded with these morphologic types. This classification according to gross appearance is of considerable value when interpreting the pathologic features of intrahepatic cholangiocarcinoma. CT seems to be a useful modality for the detection of tumors and may be consistent with their gross morphologic findings

  12. Plasmoid behavior in helical plasmas

    International Nuclear Information System (INIS)

    Ishizaki, R.; Nakajima, N.

    2009-01-01

    Full text: It is well known that an ablation cloud; a high density and low temperature plasmoid, drifts to the lower field side in tokamak plasmas, which leads to a good performance on fueling in tokamak. Such a good performance, however, has not been obtained yet in the planar axis heliotron; Large Helical Device (LHD) experiments, even if a pellet has been injected from the high field side. The purpose of the study is to clarify the difference on the plasmoid motion between tokamak and LHD plasmas by using the MHD simulation including ablation processes. It is found in tokamaks that the drift motion is induced by a tire tube force and 1/R force in the major radius direction, and that the pressure and density of the plasmoid have oscillation due to fast compressional Alfven wave. On the other hand, the upper and lower portions surrounding the plasmoid center drift to the higher field side, because 1/R force by magnetic field becomes negative in the major radius direction since the magnetic field surrounding the plasmoid is accumulated by the extremely large ablation pressure and the magnetic pressure perturbation becomes positive. It is also found that the plasmoid does not drift when the perturbation of the plasmoid is small. In addition, the motion of the plasmoid is investigated in LHD plasmas in four cases that the plasmoids are initially located at the inner and outer sides of the torus on the vertically and horizontally elongated poloidal cross sections. The plasmoids drift to the lower field sides in all cases. However, in the case that it is located at the inner side of the torus on the horizontally elongated poloidal cross section, it is found that the plasmoid drifts in the negative direction of the major radius and subsequently drifts in the positive direction of it. In other words, the plasmoid finally drifts in the positive direction of the major radius the same as the plasmoid located at the outer side of the torus. This fact might be one of the

  13. Uncommon radiologic appearance of bony hydatidosis in child

    International Nuclear Information System (INIS)

    Smida, M.; Jalel, C.; Mrad, K.; Sayed, M.; Ben Abdallah, O.; Ben Chehida, F.; Ben Ghachem, M.

    2001-01-01

    The authors report 2 cases of 2 children aging 11 and 12-years-old presenting hydatidosis in the upper extremity of 2 long bones femur and tibia. In 2 cases, radiological appearances were atypical. In the femur, plain radiographs revealed multiple lucencies, irregular, located in the superior extremity with a periosteal reaction. The CT scan confirmed these data and showed a cortical rupture, extension to soft tissue with contrast enhancement. In the tibia, plain radiographies showed delimited lucencies, confluent with a rim condensation in the proximal epiphyseal-metaphyseal area. Echography and CT are helpful when radiological appearances are unusual. (authors)

  14. Impact of new technologies on dose reduction in CT

    International Nuclear Information System (INIS)

    Lee