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Sample records for conventional digital subtraction

  1. Digital subtraction laryngography

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    Brown, B.W.; Enzmann, D.R.; Hopp, M.L.; Castellino, R.A.

    1983-06-01

    Digital subtraction laryngography was used to evaluate laryngeal function in 8 patients: 4 with normal larynxes and 4 with laryngeal disease. Subtracted digital images provided a dynamic display of the extent and symmetry of vocal cord excursions and pyriform sinus inflation, and the vocal cord resting position was also clearly depicted. The technical details of digital subtraction laryngography and its application are described.

  2. Comparison of conventional panoramic radiography and panoramic digital subtraction radiography in detection of simulated lesions of mandibular condyle

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    Panjnoush M.

    2008-12-01

    Full Text Available "n  "nBackground and Aim: Digital subtraction Radiography (DSR is a method of accurate assessing condylar head changes. several studies have been carried out in applying DSR in dentistry, however there is a few number of studies in efficacy of DSR method in assesment of condylar head changes, The aim of this study was to compare panoramic radiography and DSR detecting simulated lesions of the mandibular condyl. "nMaterials and Methods: this was a process reaserch study, in which two dry human skulls with no obvious temporomandibular joint pathology were used. Osteophytic lesions were simulated using three sizes of bone chips that were placed on the medial portion of anterior and superolateral aspects of the condyle. Osteolytic lesions were simulated making 1 and 2 mm holes using round burr in the central portion of anterior aspect and Lateral pole of the condyle. Panoramic radiographs were prepared with and without the lesions in place. These paired radiographs were digitized and digital- subtraction images of the original panoramic images were obtained. Eight observers evaluated 155 images of each modality for the presence or absence and the type of simulated lesions of the mandibular condyle. Sensitivity, specificity, reliability and measure of agreement were analyzed using kappa test and crossed tables and qualitative variables were assess by chi-square and fisher's Exact test. "nResults: Specificity of panoramic and DSR methods were 15.4% and 66.7% respectively. Sensitivity of panoramic and DSR methods were 61.1% and 80.6% for osteophytic lesions and 37.5% and 83.3% for Osteolytic lesions. The percentage of correct decisions made in DSR method was significantly more than conventional panoramic method (82.6% vs 41.9% (p<0.0001. "nConclusion: Based on the results of this study digital subtraction technique was significantly more accurate than the panoramic radiographs in detection of simulated lesions of the mandibular condyle.

  3. Digital subtraction angiography of the thoracic aorta

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    Grossman, L.B.; Buonocore, E.; Modic, M.T.; Meaney, T.F.

    1984-02-01

    Forty-three patients with acquired and congenital abnormalities of the thoracic aorta were studied using digital subtraction angiography (DSA) after an intravenous bolus injection of 40 ml of contrast material. Abnormalities studied included coarctation, pseudocoarctation, Marfan syndrome, cervical aorta, double aortic arch, aneurysm, dissection, and tumor. Twenty-four patients also had conventional angiography. DSA was accurate in 95% of cases; in the other 5%, involving patients with acute type I dissection, the coronary arteries could not be seen. The authors concluded that in 92% of their patients, DSA could have replaced the standard aortogram.

  4. The value of magnetic resonance imaging for the detection of the bleeding source in non-traumatic intracerebral haemorrhages: a comparison with conventional digital subtraction angiography

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    Lummel, Nina; Lutz, Juergen; Brueckmann, Hartmut; Linn, Jennifer [University of Munich, Department of Neuroradiology, Munich (Germany)

    2012-07-15

    Conventional digital subtraction angiography (DSA) is currently regarded as the gold standard in detecting underlying vascular pathologies in patients with intracerebral haemorrhages (ICH). However, the use of magnetic resonance imaging (MRI) in the diagnostic workup of ICHs has considerably increased in recent years. Our aim was to evaluate the diagnostic accuracy and yield of MRI for the detection of the underlying aetiology in ICH patients. Sixty-seven consecutive patients with an acute ICH who underwent MRI (including magnetic resonance angiography (MRA) and DSA during their diagnostic workup) were included in the study. Magnetic resonance images were retrospectively analysed by two independent neuroradiologists to determine the localisation and cause of the ICH. DSA was used as a reference standard. In seven patients (10.4%), a DSA-positive vascular aetiology was present (one aneurysm, four arteriovenous malformations, one dural arteriovenous fistula and one vasculitis). All of these cases were correctly diagnosed by both readers on MRI. In addition, MRI revealed the following probable bleeding causes in 39 of the 60 DSA-negative patients: cerebral amyloid angiopathy (17), cavernoma (9), arterial hypertension (8), haemorrhagic transformation of an ischaemic infarction (3) and malignant brain tumour with secondary ICH (2). Performing MRI with MRA proved to be an accurate diagnostic tool in detecting vascular malformations in patients with ICH. In addition, MRI provided valuable information regarding DSA-negative ICH causes, and thus had a high diagnostic yield in ICH patients. (orig.)

  5. Dual-energy direct bone removal CT angiography for evaluation of intracranial aneurysm or stenosis: comparison with conventional digital subtraction angiography

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    Watanabe, Yoshiyuki [National Cardiovascular Center, Department of Radiology, Osaka (Japan); St. Luke' s International Hospital, Department of Radiology, Tokyo (Japan); Uotani, Kensuke; Nakazawa, Tetsuro; Higashi, Masahiro; Yamada, Naoaki; Hori, Yoshiro; Kanzaki, Suzu; Fukuda, Tetsuya; Naito, Hiroaki [National Cardiovascular Center, Department of Radiology, Osaka (Japan); Itoh, Toshihide [Siemens Asahi Medical Technologies, Tokyo (Japan)

    2009-04-15

    Dual-energy CT can be applied for bone elimination in cerebral CT angiography (CTA). The aim of this study was to compare the results of dual-energy direct bone removal CTA (DE-BR-CTA) with those of digital subtraction angiography (DSA). Twelve patients with intracranial aneurysms and/or ICA stenosis underwent a dual-source CT in dual-energy mode. Post-processing software selectively removed bone structures using the two energy data sets. Three-dimensional images with and without bone removal were reviewed and compared to DSA. Dual-energy bone removal was successful in all patients. For 10 patients, bone removal was good and CTA maximum-intensity projection (MIP) images could be used for vessel evaluation. For two patients, bone removal was moderate with some bone remnants, but this did not inhibit the three-dimensional visualization. Three aneurysms adjacent to the skull base were only partially visible in conventional CTA but were fully visible in DE-BR-CTA. In five patients with ICA stenosis, DE-BR-CTA revealed the stenotic lesions on the MIP images. The correlation between DSA and DE-BR-CTA was good (R {sup 2}=0.822), but DE-BR-CTA led to an overestimation of stenosis. DE-BR-CTA was able to eliminate bone structure using only a single CT data acquisition and is useful to evaluate intracranial aneurysms and stenosis. (orig.)

  6. Digital contrast subtraction radiography for proximal caries diagnosis

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    Kang, Byung Cheol; Yoon, Suk Ja [Department of Dental Radiology, Chonnam National University Hospital, Gwangju (Korea, Republic of)

    2002-06-15

    To determine whether subtraction images utilizing contrast media can improve the diagnostic performance of proximal caries diagnosis compared to conventional periapical radiographic images. Thirty-six teeth with 57 proximal surfaces were radiographied using a size no.2 RVG-ui sensor (Trophy Radiology, Marne-la-Vallee, France). The teeth immersed in water-soluble contrast media and subtraction images were taken. Each tooth was then sectioned for histologic examination. The digital radiographic images and subtraction images were examined and interpreted by three dentists for proximal caries. The results of the proximal caries diagnosis were then verified with the results of the histologic examination. The proximal caries sensitivity using digital subtraction radiography was significantly higher than simply examining a single digital radiograph. The sensitivity of the proximal dentinal carious lesion when analyzed with the subtraction radiograph and the radiograph together was higher than with the subtraction radiograph or the radiograph alone. The use of subtraction radiography with contrast media may be useful for detecting proximal dentinal carious lesions.

  7. Digital subtraction angiography in pediatric cerebrovascular occlusive disease

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    Faerber, E.N.; Griska, L.A.B.; Swartz, J.D.; Capitanio, M.A.; Popky, G.L.

    1984-08-01

    While conventional angiography has been used to demonstrate cerebrovascular occlusive disease in the past, digital subtraction angiography (DSA) is capable of showing progressive vascular involvement with ease, simplicity, and extremely low morbidity, making it particularly well suited for children and outpatients either alone or coordinated with computed tomography. The authors discuss the usefulness and advantages of DSA as demonstrated in 7 infants and children with hemiplegia, 4 of whom had sickle-cell disease.

  8. Subtraction CT angiography for evaluation of intracranial aneurysms: comparison with conventional CT angiography

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    Li, Qi; Li, Kewei; Xie, Peng [The First Affiliated Hospital, Chongqing Medical University, Department of Neurology, Chongqing (China); Lv, Fajin; Li, Yongmei; Luo, Tianyou [The First Affiliated Hospital, Chongqing Medical University, Department of Radiology, Chongqing (China)

    2009-09-15

    The purpose of our study was to compare the diagnostic performance of subtraction computed tomography angiography (CTA) with conventional nonsubtracted CTA and digital subtraction angiography (DSA) for the detection of intracranial aneurysms. A total of 76 patients underwent both subtraction CTA and conventional CTA for the detection and therapy planning of suspected intracranial aneurysms. Subtraction and conventional CTA images were independently assessed by two readers in a blinded manner. The possibility of endovascular treatment or surgical clipping was also assessed based on information provided by CT angiograms alone. In 64 patients, 75 aneurysms were present on DSA. On a per-aneurysm basis, the sensitivity of subtraction CTA was 98.6% for reader 1, and 100% for reader 2. However, sensitivity of conventional CTA was 94.6% for reader 1, and 93.3% for reader 2. Therapeutic decisions could be made regarding 63 patients based on information provided by subtraction CTA images. However, conventional CTA provided sufficient information to make this decision for 55 patients. Conventional CTA has limited sensitivity in detecting very small aneurysms as well as aneurysms adjacent to bone. Subtraction CTA performed on a 64-row multidetector CT is an accurate and promising diagnostic tool that seems to be equivalent to 2D DSA for the detection and pretreatment planning of intracranial aneurysms. (orig.)

  9. Coherent bremsstrahlung used for digital subtraction angiography

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    Überall, Herbert

    2007-05-01

    Digital subtraction angiography (DSA), also known as Dichromography, using synchrotron radiation beams has been developed at Stanford University (R. Hofstadter) and was subsequently taken over at the Brookhaven Synchrotron and later at Hamburg (HASYLAB) [see, e.g., W.R. Dix, Physik in unserer Zeit. 30 (1999) 160]. The imaging of coronary arteries is carried out with an iodine-based contrast agent which need not be injected into the heart. The radiation must be monochromatized and is applied above and below the K-edge of iodine (33.16 keV), with a subsequent digital subtraction of the two images. Monochromatization of the synchrotron radiation causes a loss of intensity of 10 -3. We propose instead the use of coherent bremsstrahlung [see, e.g., A.W. Saenz and H. Uberall, Phys. Rev. B25 (1982) 448] which is inherently monochromatic, furnishing a flux of 10 12 photon/sec. This requires a 10-20 MeV electron linac which can be obtained by many larger hospitals, eliminating the scheduling problems present at synchrotrons. The large, broad incoherent bremsstrahlung background underlying the monochromatic spike would lead to inadmissible overexposure of the patient. This problem can be solved with the use of Kumakhov's capillary optics [see e.g., S.B.Dabagov, Physics-Uspekhi 46 (2003) 1053]: the low-energy spiked radiation can be deflected towards the patient, while the higher energy incoherent background continues forward, avoiding the patient who is placed several meters from the source.

  10. Digital subtraction angiography in head and neck radiology

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    Carmody, R.F.; Seeger, J.F.; Smith, R.L.; Horsley, W.W.; Miller, R.W.

    1984-07-01

    Intravenous digital subtraction angiography (IVDSA) was used to evaluate 44 patients with suspected otolaryngologic abnormalities. Sixteen had IVDSA for pulsatile tinnitus or suspected glomus tumor of the petrous bone. Nine patients were evaluated because of pulsatile neck masses, and 12 others had suspected tumors of the neck, face, and paranasal sinuses. Seven had IVDSA following head and neck trauma. The technique of examination is described. The current indications of IVDSA in head and neck radiology are discussed. It is concluded that IVDSA is a suitable substitute for conventional angiography for many otolaryngologic conditions and, because of its safety, can be used more liberally.

  11. Use of digital subtraction angiography for assessment of digital replantatlon

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    Liu-hong WANG; Guang-qiang ZHANG

    2012-01-01

    Objective:To assess the blood flow of the proper digital artery using digital subtraction angiography (DSA) in the early stage after replantation.Methods:From January 2006 to October 2010,27 anastomosed arteries in 27 replanted digits were included in the study.The patients included nine males and four females.The patients received DSA at 48 to 96 h after digital replantation.Based on DSA image,the blood flow was classified into normal,slow-running,and flow-stopping types.The patients with normal digital blood flow were given continuous routine treatments; the patients with slow-running flow were given the conservative treatments,such as release of the tight dressings,removal of stitches,keeping warm,the use of massage,and the use of anticoagulants and anti-inflammatory drugs; the patients with flow-stopping received immediate surgical re-exploration.Results:In this series,23 digits in 11 patients showed a normal blood flow,and these digits all survived.In one of 13 patients,two digits which displayed slow-running flow also survived after conservative treatments.In two of 13 patients,two digits showed flow stopping,with one surviving and one failing after re-exploration and arterial revision.Conclusions:The DSA can be used to assess the blood flow of the proper digital artery in the early stage after replantation.It provides essential information for salvaging the replanted finger.

  12. Value of intravenous digital subtraction angiography for amaurosis fugax

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    Horio, Shunji; Uchida, Sunao

    1987-07-01

    We performed intravenous digital subtraction angiography (IVDSA) in 12 cases of amaurosis fugax to evaluate the arteries in the head and neck region. We could detect stenosis or irregularity in the arterial wall in 5 cases (46 %). These 5 cases were treated with surgical or medical antiplatelet therapy. Amaurosis fugax disappeared in all treated cases. We also performed IVDSA in 11 cases with obstructive retinal vascular diseases. Stenosis of internal carotid artery was detected in one case (9 %). IVDSA proved thus to be of value in detecting abnormalities of carotid artery and its tributaries. While it is unlikely that IVDSA will replace conventional intraarterial angiography, IVDSA is much safer than direct arterial puncture and does not require admission in hospital.

  13. Digital subtraction angiography of the cerebral vessels by intraarterial injection

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    Nagata, Izumi; Kikuchi, Haruhiko; Karasawa, Jun; Mitsugi, Toru; Naruo, Yoshito; Takamiya, Makoto (National Cardiovascular Center, Suita, Osaka (Japan))

    1984-10-01

    Three hundred and fifty-seven digital subtraction angiography (DSA) were performed in 184 neurosurgical patients by intraarterial injection. Examinations consisted of 192 carotid angiography, 110 vertebral angiography, 23 aortography, 11 spinal angiography and 21 other angiography. In all examinations, visualization of the vessels was excellent and the complications were never experienced. High contrast sensitivity of DSA resulted in better visualization of tumor stains, phlebogram, and arteries in cerebral arteriovenous malformations with large shunt blood flow than conventional angiography. Selective catheterization into each cerebral arteries was not necessarily demanded for good opacification of the vessels because of high sensitivity. High contrast sensitivity also permitted low concentration of contrast material, small dose of contrast material, and slow injection rate. Low concentration of contrast material reduced pain and heat during injection especially in the external carotid and vertebral angiography. Using slow injection, recoiling of catheter into the aorta was reduced, so that injection from the innominate and subclavian arteries for visualization of origin of the cerebral arteries were always successful. Full study of cerebral arteries by Seldinger's method, if necessary, was easily achieved using DSA even in patient with high age or with severe atherosclerosis. Bolus injection of small dose of contrast material as well as serial imaging was helpful in evaluating hemodynamics in the lesion. Real time display of DSA reduced the time required for angiography and was very convenient for artificial embolization. Besides these advantages, DSA became comparable to conventional angiography in spacial resolution by use of intraarterial injection and could be a preoperative genuine examination as well as a screening method.

  14. Digital subtraction angiography in cerebral infarction

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    Cho, Sin Young; Kim, Ji Hun; Suh, Hong Kil; Kim, Hyo Heon; Kwack, Eun Young; Lee, Il Seong [College of Medicine Hallym University, Seoul (Korea, Republic of)

    1995-01-15

    The usefulness and radiographic findings of the angiography in cerebral infarction are well known. We attempted to evaluate the angiographic causes, findings, and the usefulness of DSA in cerebral infarction. The authors reviewed retrospectively DSA images of 51 patients who were diagnosed as having cerebral infarction by brain CT and/or MRI and clinical settings. DSA was performed in all 51 patients, and in 3 patients, conventional angiogram was also done. Both carotid DSA images were obtained in AP, lateral, oblique projections, and one or both vertebral DSA images in AP and lateral. The authors reviewed the patient's charts for symptoms, operative findings and final diagnosis, and analysed DSA findings of cerebral atherosclerosis with focus on 6 major cerebral arteries. Among the 51 patients of cerebral infarction 43 patients (84.3%) had cerebral atherosclerosis, 1 dissecting aneurysm, 1 moyamoya disease and 6 negative in angiogram. DSA findings of cerebral atherosclerosis were multiple narrowing in 42 patients (97.7%), tortuosity in 22 (51.2%), dilatation in 14, occlusion in 12, avascular region in 8, collaterals in 7, ulcer in 6, and delayed washout of contrast media in 3. In cerebral atherosclerosis, internal carotid artery was involved in 37 patients (86.0%), middle cerebral artery in 29 (67.4%) posterior cerebral artery in 28, anterior cerebral artery in 26, vertebral artery in 22, and basilar artery in 15. Intracranial involvement of cerebral atherosclerosis (64.9%) was more common than extracranial involvement (16.2%). In cerebral infarction MRA may be the screening test, but for more precise evaluation of vascular abnormality and its extent, DSA should be considered.

  15. Accuracy of digital subtraction radiography in combination with a contrast media in assessment of proximal caries depth

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    Farzad Esmaeili

    2008-07-01

    Full Text Available Background and aims. Radiography is used to diagnose the demineralization process and carious lesions; however, conventional radiography and direct digital images do not show these lesions when the amount of demineralization is less than 40%. Digital subtraction radiography has recently been used to improve the diagnostic quality of these lesions. The purpose of this study was to compare the caries depth estimated by digital subtraction radiography in combination with barium sulfate in diagnosing proximal dental caries with histopathologic evaluation. Materials and methods. In this study 30 molars and premolars (24 demineralized lesions with cavity, 8 without cavity were studied. Direct digital images were taken (kVp: 68, mA: 8; t: 0.12 for premolars and t: 0.16 for molars whereas the position of X-ray tube and CCD receptor and teeth was fixed. To prepare the second images 135 gr/L barium sulfate was used. The images obtained with the same exposure and geometry and then subtracted. The depth of the lesions in direct digital and subtracted images were assessed and compared with the depth measured in histopathologic assessments. Results. The mean depths (± SD of the lesions were 1.80 ± 0.77 mm in direct digital radiography, 2.32 ± 0.76 mm in subtracted images after barium sulfate treatment, and 2.51 ± 0.43 mm in histopathologic sections. The statistical difference between direct digital radiography and the other methods was significant (P < 0.05. However, the differences were not statistically significant between subtracted images and histopathologic sections. The average intra-class correlation coefficient was 0.7241 (CI: 95%. Conclusion. The present study has demonstrated that digital subtraction radiography images have the potential to measure the depth of proximal caries with no significant difference with histopathologic evaluation.

  16. The potential for neurovascular intravenous angiography using K-edge digital subtraction angiography

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    Schültke, E.; Fiedler, S.; Kelly, M.; Griebel, R.; Juurlink, B.; LeDuc, G.; Estève, F.; Le Bas, J.-F.; Renier, M.; Nemoz, C.; Meguro, K.

    2005-08-01

    Background: Catheterization of small-caliber blood vessels in the central nervous system can be extremely challenging. Alternatively, intravenous (i.v.) administration of contrast agent is minimally invasive and therefore carries a much lower risk for the patient. With conventional X-ray equipment, volumes of contrast agent that could be safely administered to the patient do not allow acquisition of high-quality images after i.v. injection, because the contrast bolus is extremely diluted by passage through the heart. However, synchrotron-based digital K-edge subtraction angiography does allow acquisition of high-quality images after i.v. administration of relatively small doses of contrast agent. Materials and methods: Eight adult male New Zealand rabbits were used for our experiments. Animals were submitted to both angiography with conventional X-ray equipment and synchrotron-based digital subtraction angiography. Results: With conventional X-ray equipment, no contrast was seen in either cerebral or spinal blood vessels after i.v. injection of iodinated contrast agent. However, using K-edge digital subtraction angiography, as little as 1 ml iodinated contrast agent, when administered as i.v. bolus, yielded images of small-caliber blood vessels in the central nervous system (both brain and spinal cord). Conclusions: If it would be possible to image blood vessels of the same diameter in the central nervous system of human patients, the synchrotron-based technique could yield high-quality images at a significantly lower risk for the patient than conventional X-ray imaging. Images could be acquired where catheterization of feeding blood vessels has proven impossible.

  17. Role of digital tomosynthesis and dual energy subtraction digital radiography in detecting pulmonary nodules

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    Kumar, Sarvana G. [Department of Radiodiagnosis and Imaging, Postgraduate Institute of Medical Education and Research (PGIMER), Sector 12, Chandigarh 160012 (India); Garg, Mandeep Kumar, E-mail: gargmandeep01@gmail.com [Department of Radiodiagnosis and Imaging, Postgraduate Institute of Medical Education and Research (PGIMER), Sector 12, Chandigarh 160012 (India); Khandelwal, Niranjan; Gupta, Pankaj [Department of Radiodiagnosis and Imaging, Postgraduate Institute of Medical Education and Research (PGIMER), Sector 12, Chandigarh 160012 (India); Gupta, Dheeraj; Aggarwal, Ashutosh Nath [Department of Pulmonary Medicine, Postgraduate Institute of Medical Education and Research (PGIMER), Sector 12, Chandigarh 160012 (India); Bansal, Subash Chand [Department of Radiodiagnosis and Imaging, Postgraduate Institute of Medical Education and Research (PGIMER), Sector 12, Chandigarh 160012 (India)

    2015-07-15

    Highlights: • Accuracy of digital tomosynthesis for nodule detection is substantially higher. • Improvement in diagnostic accuracy is most pronounced for nodules <10 mm. • There is five times increase in radiation dose compared to DR. - Abstract: Objective: Digital tomosynthesis (DT) and dual-energy subtraction digital radiography (DES-DR) are known to perform better than conventional radiography in the detection of pulmonary nodules. Yet the comparative diagnostic performances of DT, DES-DR and digital radiography (DR) is not known. The present study compares the diagnostic performances of DT, DES-DR and DR in detecting pulmonary nodules. Subjects and methods: The institutional Review Board approved the study and informed written consent was obtained. Fifty-five patients (30 with pulmonary nodules, 25 with non-nodular focal chest pathology) were included in the study. DT and DES-DR were performed within14 days of MDCT. Composite images acquired at high kVp as part of DES-DR were used as DR images. Images were analyzed for presence of nodules and calcification in nodules. Interpretations were assigned confidence levels from 1 to 5 according to Five-Point rating scale. Areas under the receiver operating characteristic curves were compared using Z test. Results: A total of 110 (88 non-calcified, 22 calcified) nodules were identified on MDCT. For detection of nodules, DR showed cumulative sensitivity and specificity of 25.45% and 67.97%, respectively. DT showed a cumulative sensitivity and specificity of 60.9% and 85.07%, respectively. The performance was significantly better than DR (p < 0.003). DES-DR showed sensitivity and specificity of 27.75% and 82.64%, not statistically different from those of DR (p—0.92). In detection of calcification, there was no statistically significant difference between DT, DES-DR and DR. Conclusions: DT performs significantly better than DES-DR and DR at the cost of moderate increase in radiation dose.

  18. Accuracy of digital subtraction radiography in combination with a contrast media in assessment of proximal caries depth.

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    Valizadeh, Solmaz; Ehsani, Sara; Esmaeili, Farzad; Tavakoli, Mohammad Amin

    2008-01-01

    Radiography is used to diagnose the demineralization process and carious lesions; however, conventional radiography and direct digital images do not show these lesions when the amount of demineralization is less than 40%. Digital subtraction radiography has recently been used to improve the diagnostic quality of these le-sions. The purpose of this study was to compare the caries depth estimated by digital subtraction radiog-raphy in combination with barium sulfate in diag-nosing proximal dental caries with histopathologic evaluation. In this study 30 molars and premolars (24 demineralized lesions with cavity, 8 without cavity) were studied. Direct digital images were taken (kVp: 68, mA: 8; t: 0.12 for premolars and t: 0.16 for molars) whereas the position of X-ray tube and CCD receptor and teeth was fixed. To prepare the second images 135 gr/L barium sulfate was used. The images obtained with the same exposure and geometry and then subtracted. The depth of the lesions in direct digital and subtracted images were assessed and compared with the depth measured in histopathologic assessments. The mean depths (± SD) of the lesions were 1.80 ± 0.77 mm in direct digital radiography, 2.32 ± 0.76 mm in subtracted images after barium sulfate treatment, and 2.51 ± 0.43 mm in histopathologic sections. The statistical difference between direct digital radiography and the other methods was significant (P digital subtraction radiography images have the potential to measure the depth of proximal caries with no significant difference with histopathologic evaluation.

  19. The Principle of Digital Subtraction Angiography and Radiological Protection

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    Okamoto, K.; Ito, J.; Sakai, K.; Yoshimura, S.

    2000-01-01

    Summary Recent improvements in x-ray technology have greatly contributed to the advancement of diagnostic imaging. Fluoroscopically guided neurointerventional procedures with digital subtraction angiography (DSΛ) are being performed with increasing frequency as the treatment of choice for a variety of neurovascular diseases. Radiation-induced skin injuries can occur after extended fluoroscopic exposure times, and the injuries have recently been reported. In this article, measured radiation doses at the surface of Rando Phantom with Skin Dose Monitor, and estimated and measured entrance skin doses in patients underwent neurointerventional procedures are reported as well as means of reducing radiation doses absorbed by patients and personnel to avoid occurrence of radiation-induced injuries. PMID:20667218

  20. Gadobutrol: an alternative contrast agent for digital subtraction dacryocystography

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    Priebe, M.; Mohr, A.; Brossmann, J.; Heller, M.; Frahm, C. [Department of Diagnostic Radiology, Christian-Albrechts-University of Kiel, Arnold-Heller-Strasse 9, 24105 Kiel (Germany)

    2002-08-01

    We report the application of gadobutrol as a contrast medium for digital subtraction dacryocystography (DS-DCG) in patients with known allergy to iodinated contrast agent. Gadobutrol has the double gadolinium concentration (1.0 mmol/ml) of other gadolinium-based contrast agents. Quality of the DS-DCG images obtained with gadobutrol was comparable to DS-DCG images obtained with iodinated contrast medium. Radiodensity measurements using a micro-CT scanner confirmed a high radiodensity of gadobutrol which was comparable to the radiodensity of iopentol with a iodine concentration of 250 mg/ml and only approximately 20% lower than the radiodensity of iopentol with a concentration of 300 mg/l. Gadobutrol is a well-suited substitute for DS-DCG in patients with allergy to iodinated contrast agents. (orig.)

  1. Intravenous digital subtraction angiography in patients with coarctation of the aorta (stenosis of the aortic isthmus)

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    Rauber, K.; Kollath, J.

    1985-02-01

    The authors report on 18 patients with stenoses of the aortic isthmus in whom digital subtraction angiography had been carried out. In three patients DSA yielded the primary diagnosis of a postductal stenosis of the aortic isthmus. In all postoperative patients, restenosis of the aorta could either be excluded or confirmed. In three cases with complications after an operation, DSA supplied diagnostic information which was decisive for proceeding further. According to the authors' experience, intravenous DSA can replace conventional angiography in the majority of postoperative controls and in future also in primary diagnosis.

  2. Diagnosis of carotid body tumor by digital subtraction angiography

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    戚跃勇; 邹利光; 孙清荣; 徐健; 周政; 谭颖徽

    2004-01-01

    Objective: To make a further understanding of the features of the carotid body tumor (CBT) by digital subtraction angiography (DSA) so as to explore the clinical value of DSA diagnosis and interventional therapy for CBT. Methods: DSA data from 12 cases of CBT were analyzed retrospectively. A consensus interpretation of the DSA appearances in all of the patients was reached after dynamic observation by 2 experienced radiologists in a double-blind manner. Results: Definite diagnosis in all cases could be made by DSA. The DSA features of the CBT included bigger bifurcation angles of the internal and external carotid arteries, displacement of internal and external carotid arteries, CBT supplied by external carotid arteries in most cases and the significant increase of tumor blood vessels in bifurcation. Invasion of internal or external carotid arteries was found in 6 cases. Smaller stained area of the tumor and significantly reduced intraoperative bleeding were found after embolization of the supplying arteria in 2 cases. Conclusion: DSA is the effective method for the diagnosis and preoperative assessment of CBT. Preoperative embolization of CBT may contribute to the reduced intraoperative bleeding.

  3. The concept of apparent cardiac arrest as a prerequisite for coronary digital subtraction angiography

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    Werf, T. van der; Heethaar, R.M.; Stegehuis, H.; Meijler, F.L.

    1984-01-01

    This study was undertaken to evaluate the possible use of digital subtraction applied after selective coronary arteriography. An identical position of the objects with and without contrast medium is an absolute requirement for the application of subtraction techniques. Because coronary arteries are

  4. Digital subtraction peripheral angiography using image stacking: initial clinical results.

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    Kump, K S; Sachs, P B; Wilson, D L

    2001-07-01

    Using clinically acquired x-ray angiography image sequences, we compared three algorithms for creating a single diagnostic quality image that combined input images containing flowing contrast agent. These image-stacking algorithms were: maximum opacity with the minimum gray-scale value across time recorded at each spatial location, (REC) recursive temporal filtering followed by a maximum opacity operation, and (AMF) an approximate matched filter consisting of a convolution with a kernel approximating the matched filter followed by a maximum opacity operation. Eighteen clinical exams of the peripheral arteries of the legs were evaluated. AMF gave 2.7 times greater contrast to noise ratio than the single best subtraction image and 1.3 times improvement over REC, the second best stacking algorithm. This is consistent with previous simulations showing that AMF performs nearly equal to the optimal result from matched filtering without the well-known limitations. For example, unlike matched filtering, AMF filter coefficients were obtained automatically using an image-processing algorithm. AMF effectively brought out small collateral arteries, otherwise difficult to see, without degrading artery sharpness or stenosis grading. Comparing results using reduced and full contrast agent volumes demonstrated that contrast agent load could be reduced to one-third of the conventional amount with AMF processing. By simulating reduced x-ray exposures on clinical exams, we determined that x-ray exposure could be reduced by 80% with AMF processing. We conclude that AMF is a promising, potential technique for reducing contrast agent load and for improving vessel visibility, both very important characteristics for vascular imaging.

  5. K-edge digital subtraction imaging based on a dichromatic and compact x-ray source

    Science.gov (United States)

    Sarnelli, A.; Taibi, A.; Tuffanelli, A.; Baldazzi, G.; Bollini, D.; Cabal Rodriguez, A. E.; Gombia, M.; Prino, F.; Ramello, L.; Tomassi, E.; Gambaccini, M.

    2004-07-01

    This work proposes a compact dichromatic imaging system for the application of the K-edge digital subtraction technique based on a conventional x-ray tube and a monochromator system. A quasi-monochromatic x-ray beam at the energy of iodine K-edge is produced by Bragg diffraction on a mosaic crystal. Two thin adjacent beams with energies that bracket the K-edge discontinuity are obtained from the diffracted beam by means of a proper collimation system. They are then detected using an array of Si detectors. A home-made phantom is used to study the image quality as a function of iodine concentration. Signal and signal-to-noise ratio analysis has also been performed. The results are compared with theoretical expectations.

  6. K-edge digital subtraction imaging based on a dichromatic and compact x-ray source

    Energy Technology Data Exchange (ETDEWEB)

    Sarnelli, A [Dipartimento di Fisica dell' Universita di Ferrara and INFN Sezione di Ferrara, Via Paradiso 12, I-44100 Ferrara (Italy); Taibi, A [Dipartimento di Fisica dell' Universita di Ferrara and INFN Sezione di Ferrara, Via Paradiso 12, I-44100 Ferrara (Italy); Tuffanelli, A [Dipartimento di Fisica dell' Universita di Ferrara and INFN Sezione di Ferrara, Via Paradiso 12, I-44100 Ferrara (Italy); Baldazzi, G [Dipartimento di Fisica dell' Universita di Bologna and INFN Sezione di Bologna, Viale Berti Pichat 64/2, 40127 Bologna (Italy); Bollini, D [Dipartimento di Fisica dell' Universita di Bologna and INFN Sezione di Bologna, Viale Berti Pichat 64/2, 40127 Bologna (Italy); Rodriguez, A E Cabal [CAEDAN, Havana (Cuba); Gombia, M [Dipartimento di Fisica dell' Universita di Bologna and INFN Sezione di Bologna, Viale Berti Pichat 64/2, 40127 Bologna (Italy); Prino, F [Dipartimento di Scienze e Tecnologie Avanzate, Universita del Piemonte Orientale and INFN Sezione di Alessandria, C.so, Borsalino 54, I-15100 Alessandria (Italy); Ramello, L [Dipartimento di Scienze e Tecnologie Avanzate, Universita del Piemonte Orientale and INFN Sezione di Alessandria, C.so, Borsalino 54, I-15100 Alessandria (Italy); Tomassi, E [Dipartimento di Scienze e Tecnologie Avanzate, Universita del Piemonte Orientale and INFN Sezione di Alessandria, C.so, Borsalino 54, I-15100 Alessandria (Italy); Gambaccini, M [Dipartimento di Fisica dell' Universita di Ferrara and INFN Sezione di Ferrara, Via Paradiso 12, I-44100 Ferrara (Italy)

    2004-07-21

    This work proposes a compact dichromatic imaging system for the application of the K-edge digital subtraction technique based on a conventional x-ray tube and a monochromator system. A quasi-monochromatic x-ray beam at the energy of iodine K-edge is produced by Bragg diffraction on a mosaic crystal. Two thin adjacent beams with energies that bracket the K-edge discontinuity are obtained from the diffracted beam by means of a proper collimation system. They are then detected using an array of Si detectors. A home-made phantom is used to study the image quality as a function of iodine concentration. Signal and signal-to-noise ratio analysis has also been performed. The results are compared with theoretical expectations.

  7. The Reduction Of Motion Artifacts In Digital Subtraction Angiography By Geometrical Image Transformation

    Science.gov (United States)

    Fitzpatrick, J. Michael; Pickens, David R.; Mandava, Venkateswara R.; Grefenstette, John J.

    1988-06-01

    In the diagnosis of arteriosclerosis, radio-opaque dye is injected into the interior of the arteries to make them visible. Because of its increased contrast sensitivity, digital subtraction angiography has the potential for providing diagnostic images of arteries with reduced dye volumes. In the conventional technique, a mask image, acquired before the introduction of the dye, is subtracted from the contrast image, acquired after the dye is introduced, to produce a difference image in which only the dye in the arteries is visible. The usefulness of this technique has been severely limited by the image degradation caused by patient motion during image acquisition. This motion produces artifacts in the difference image that obscure the arteries. One technique for dealing with this problem is to reduce the degradation by means of image registration. The registration is carried out by means of a geometrical transformation of the mask image before subtraction so that it is in registration with the contrast image. This paper describes our technique for determining an optimal transformation. We employ a one-to-one elastic mapping and the Jacobian of that mapping to produce a geometrical image transformation. We choose a parameterized class of such mappings and use a heuristic search algorithm to optimize the parameters to minimize the severity of the motion artifacts. To increase the speed of the optimization process we use a statistical image comparison technique that provides a quick approximate evaluation of each image transformation. We present the experimental results of the application of our registration system to mask-contrast pairs, for images acquired from a specially designed phantom (described in a companion paper), and for clinical images.

  8. Proximal caries detection using digital subtraction radiography in the artificial caries activity model

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jong Hoon; Lee, Gi Ja; Choi, Sam Jin; Park, Young Ho; Kim, Kyung Soo; Jin, Hyun Seok; Hong, Kyung Won; Oh, Berm Seok; Park, Hun Kuk [Department of Biomedical Engineering, School of Medicine, Kyung Hee University, Seoul (Korea, Republic of); Choi, Yong Suk; Hwang, Eui Hwan [Department of Oral and Maxillofacial Radiology, Institute of Oral Biology, School of Dentistry, Kyung Hee University, Seoul (Korea, Republic of)

    2009-03-15

    The purpose of the experiment was to evaluating the diagnostic ability of dental caries detection using digital subtraction in the artificial caries activity model. Digital radiographs of five teeth with 8 proximal surfaces were obtained by CCD sensor (Kodak RVG 6100 using a size no.2). The digital radiographic images and subtraction images from artificial proximal caries were examined and interpreted. In this study, we proposed novel caries detection method which could diagnose the dental proximal caries from single digital radiographic image. In artificial caries activity model, the range of lesional depth was 572-1,374 {mu}m and the range of lesional area was 36.95-138.52 mm{sup 2}. The lesional depth and the area were significantly increased with demineralization time (p<0.001). Furthermore, the proximal caries detection using digital subtraction radiography showed high detection rate compared to the proximal caries examination using simple digital radiograph. The results demonstrated that the digital subtraction radiography from single radiographic image of artificial caries was highly efficient in the detection of dental caries compared to the data from simple digital radiograph.

  9. Clinical evaluation of intravenous digital subtraction angiography in chest diseases in the elderly

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, Kazuhide; Adachi, Satoru; Suzuki, Kanzo and others

    1988-01-01

    To evaluate the image quality, we performed intravenous digital subtraction angiography for various chest diseases in 62 elderly subjects. In large vessel diseases in the chest, adequate imaging was possible in most cases, especially in the main, right and left pulmonary artery and the aorta. However, second order (subsegmental) and more distal order branches were sometimes judged unsatisfactory because of poor image quality. Five cases were evaluated as inadequate because of motion, i.e. respiratory or cardiac movement. The pulmonary circulating time was measured by the time density curve of the pulmonary artery and vein by digital subtraction angiography, and converse correlation between pulmonary circulating time and cardiac index was obtained. Thus it was possible to evaluate the pulmonary circulating dynamics. As mentioned above, intravenous digital subtraction angiography was a useful and safe method for chest diseases, especially in evaluation of large vessels in the elderly.

  10. Titanium plate artefact mimicking popliteal artery dissection on digital subtraction CT angiography.

    Science.gov (United States)

    Woodacre, Timothy; Wienand-Barnett, Sophie

    2013-04-05

    Titanium plates used for the internal fixation of long bone fractures cause significant artefact on CT scans but have not been reported to affect digital subtraction CT angiography. We present a patient with clinical suspicion of popliteal artery injury following a high tibial osteotomy. The osteotomy was stabilised with a titanium locking plate. During the digital subtraction process used to produce reconstruction CT angiography, removal of artefact caused by the titanium plate produced CT images mimicking the appearance of a popliteal artery dissection. The imaging inaccuracy was realised prior to the patient undergoing further intervention. We highlight the potential error caused by titanium plates on digital subtraction CT angiography and recommend careful analysis of such images prior to further treatment.

  11. Procedures for imaging of hemodialysis fistulas with particular reference to digital subtraction angiography (DSA)

    Energy Technology Data Exchange (ETDEWEB)

    Neufang, K.F.R.; Erasmi-Koerber, H.; Wimmer, G.

    1983-05-01

    All angiographic procedures established for imaging of hemodialysis fistulas, such as direct venous angiography, intravenous subtraction angiography and arteriography by direct puncture of the brachial artery by Seldinger's transfemoral technique, can also be effected with digital image processing. Depending on the angiographic technique, the use of digital subtraction angiography has several advantages: lower doses and concentrations of the contrast agent, lower risk of complications (thrombosis of the fistula, vasospasm) and freedom from pain. In addition, there is a marked reduction of examination time and film cost.

  12. Suppression of DC term in Fresnel digital holography by sequence subtraction of holograms

    CERN Document Server

    Kang, Jong-Chol; Im, Song-Jin

    2016-01-01

    An experimental method for suppression of DC term in the reconstructed images from Fresnel digital holograms is presented. In this method, two holograms for the same object are captured sequentially and subtracted. Since these two holograms are captured at different moments, they are slightly different from each other for fluctuations of noises. The DC term is suppressed in the image reconstructed from the subtraction hologram, while the two virtual and real images are successfully reconstructed. This method can be potentially used for the improvement of image quality reconstructed from Fresnel digital holograms.

  13. Acquisition-related motion compensation for digital subtraction angiography.

    Science.gov (United States)

    Ionasec, Razvan Ioan; Heigl, Benno; Hornegger, Joachim

    2009-06-01

    Subtraction methods in angiography are generally applied in order to enhance the visualization of blood vessels by eliminating bones and surrounding tissues from X-ray images. The main limitation of these methods is the sensitivity to patient movement, which leads to artifacts and reduces the clinical value of the subtraction images. In this paper we present a novel method for rigid motion compensation with primary application to road mapping, frequently used in image-guided interventions. Using the general concept of image-based registration, we optimize the physical position and orientation of the C-arm X-ray device, thought of as the rigid 3D transformation accounting for the patient movement. The registration is carried out using a hierarchical optimization strategy and a similarity measure based on the variance of intensity differences, which has been shown to be most suitable for fluoroscopic images. Performance evaluation demonstrated the capabilities of the proposed approach to compensate for potential intra-operative patient motion, being more resilient to the fundamental problems of pure image-based registration.

  14. Digital subtraction angiography in the diagnosis of invasive hydatidiform mole. Comparison with PAG, CT and USG

    Energy Technology Data Exchange (ETDEWEB)

    Ikuma, Kenichiro; Daimon, Michiko; Muranaka, Junko; Suno, Shigeo; Takayasu, Yukio; Shibahara, Hiroaki; Sawai, Hideaki

    1987-11-01

    Pelvic angiography (PAG) by Seldinger is one of the most useful examinations for the diagnosis of trophoblastic disease and also for the assessment of the therapeutic results. This technique, however, causes some stress to the patient. Therefore, noninvasive method, such as computed tomography (CT) and ultrasonography (USG) have recently been introduced. In the 1980s, digital subtraction angiography (DSA) was developed. It is now being used increasingly in the fields of Obstetrics and Gynecology as a substitute for the conventional PAG. In this report, the results of DSA, PAG, CT and USG which were carried out before and after chemotherapy in a patient with invasive hydatidiform mole were compared. In terms of the location, size and shape of the lesion, the CT findings were almost the same as those of USG. In terms of the angiographic findings in the affected area, intravenous DSA (IVDSA) was a sufficiently substitutional examination for conventional PAG. With IVDSA, arterial images can be obtained following the intravenous injection of a contrast medium. Therefore, this technique is excellent in terms of simplicity and safety. From now on, DSA will be utilized instead of PAG as an effective diagnostic method for trophoblastic disease and for follow-up such cases.

  15. Experience with intravenous digital subtraction angiography following shunting in 4 cases of congenital heart diseases

    Energy Technology Data Exchange (ETDEWEB)

    Higashidate, Masafumi; Konno, Susumu; Sumitomo, Naokata; Ito, Sango; Kobayashi, Hiroshi

    1985-01-01

    Intravenous digital subtraction angiography (IV-DSA) was performed in two patients with Fallot's tetralogy who underwent Blalock-Taussing operation, a patient with coarctation of the aortic arch who underwent extra-anastomic bypass between the ascending aorta and the descending aorta, and a patient with stenosis of the tricuspid valve who underwent Fontan type operation (anastomosis between the right atrium and the pulmonary artery). The conventional cardiac angiography was also performed for the comparison with IV-DSA in all patients. IV-DSA revealed the thickness of the subclavian artery anastomosed by Blaloch-Taussing operation, but failed to determine the accurate thickness of the pulmonary artery required for PA-index for radical surgery in cases of Fallot's tetralogy. Bypass from the ascending aorta to the descending aorta was well visualized by IV-DSA because the heart did not overlap on the image. In cases of Fontan type operation, IV-DSA permitted the visualization of blood flow from the right atrium to the pulmonary artery and the shape of the pulmonary artery. It is concluded that IV-DSA is a less invasive, simple technique to evaluate patients' condition following shunting for congenital heart diseases, as compared to the conventional method. (Namekawa, K.).

  16. Projection-based energy weighting on photon-counting X-ray images in digital subtraction mammography: a feasibility study

    Science.gov (United States)

    Choi, Sung-Hoon; Lee, Seung-Wan; Choi, Yu-Na; Lee, Young-Jin; Kim, Hee-Joung

    2014-03-01

    In digital subtraction mammography where subtracts the one image (with contrast medium) from the other (anatomical background) for observing the tumor structure, tumors which include more blood vessels than normal tissue could be distinguished through the enhancement of contrast-to-noise ratio (CNR). In order to improve CNR, we adopted projection-based energy weighting for iodine solutions with four different concentrations embedded in a breast phantom (50% adipose and 50% glandular tissues). In this study, a Monte Carlo simulation was used to simulate a 40 mm thickness breast phantom, which has 15 and 30 mg/cm3 iodine solutions with two different thicknesses, and an energy resolving photon-counting system. The input energy spectrum was simulated in a range of 20 to 45 keV in order to reject electronic noise and include k-edge energy of iodine (33.2 keV). The results showed that the projection-based energy weighting improved the CNR by factors of 1.05-1.86 compared to the conventional integrating images. Consequently, the CNR of images from the digital subtraction mammography could be improved by the projection-based energy weighting with photon-counting detectors.

  17. Digital subtraction cystography for detection of communicating holes of spinal extradural arachnoid cysts

    Energy Technology Data Exchange (ETDEWEB)

    Gu, Kyo Won; Kwon, Jong Won; Kim, Eun Sang [Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of)

    2016-02-15

    The purpose of this study was to demonstrate the usefulness of digital subtraction cystography to identify communicating holes between a spinal extradural arachnoid cyst (SEAC) and the subarachnoid space prior to cyst removal and hole closure. Six patients with SEAC were enrolled in this retrospective study. Digital subtraction cystography and subsequent CT myelography were performed for every patient. The presence and location of the communicating holes on cystography were documented. We evaluated the MRI characteristics of the cysts, including location, size, and associated spinal cord compression; furthermore, we reviewed cystographic images, CT myelograms, procedural reports, and medical records for analysis. If surgery was performed after cystography, intraoperative findings were compared with preoperative cystography. The location of the communicating hole between the arachnoid cyst and the subarachnoid space was identified by digital subtraction cystography in all cases (n = 6). Surgical resection of SEAC was performed in 4 patients, and intraoperative location of the communicating hole exactly corresponded to the preoperative identification. Fluoroscopic-guided cystography for SEAC accurately demonstrates the presence and location of dural defects. Preoperative digital subtraction cystography is useful for detection of a communicating hole between a cyst and the subarachnoid space.

  18. Digital subtraction angiography and intraarterial contrast medium injection for coronary examinations

    Energy Technology Data Exchange (ETDEWEB)

    Tobio, R.; Kallmeyer, C.; Castello, J.

    1985-01-01

    Digital subtraction angiography (DSA) is an established method of vasography, most extensively used as i.v. DSA. Intraarterial injection, however, applying selective or non-selective contrast medium injection, seems to be at least as important a technique although it has not yet met with corresponding interest. The article explains advantages of the technique for angiographic examinations, in particular of coronary angiography.

  19. [The improved design of table operating box of digital subtraction angiography device].

    Science.gov (United States)

    Qi, Xianying; Zhang, Minghai; Han, Fengtan; Tang, Feng; He, Lemin

    2009-12-01

    In this paper are analyzed the disadvantages of CGO-3000 digital subtraction angiography table Operating Box. The authors put forward a communication control scheme between single-chip microcomputer(SCM) and programmable logic controller(PLC). The details of hardware and software of communication are given.

  20. Digital subtraction angiography for tumours of the ear, nose and throat

    Energy Technology Data Exchange (ETDEWEB)

    Langer, M.; Zwicker, C.; Eichstaedt, H.; Maeurer, J.

    1986-08-01

    Intravenous and intra-arterial digital subtraction angiography is able to demonstrate hypervascular tumours in the ear, nose and throat territory. Direct puncture of a venous bypass used for intra-arterial chemotherapy, within the external carotid artery territory, is devoid of risk and can be used for assessing the accessibility of the tumour. Lesions of low vascularity can only be recognised by DSA on the basis of vessel displacement. These lesions are not a primary indication for examination by digital angiography. (orig).

  1. Accuracy of Digital Subtraction Radiography in the Detection of Vertical Root Fractures.

    Science.gov (United States)

    Queiroz, Polyane Mazucatto; Nascimento, Helena Aguiar Ribeiro; da Paz, Thais Diniz Jacome; Anacleto, Felipe Nogueira; Freitas, Deborah Queiroz

    2016-06-01

    The objective of this study was to evaluate the accuracy of digital subtraction radiography in the diagnosis of vertical root fractures (VRFs). Twenty decoronated uniradicular human teeth were placed in the alveoli of a dry mandible and radiographed twice, first without (unfilled roots) and then with (filled roots) a gutta-percha cone placed into the root canal. Roots were then removed from the dry mandible, and vertical fractures were created with the aid of a universal testing machine. The fractured roots were repositioned in the mandibular alveoli and again radiographed twice. Radiographic images were subtracted by using the Regeemy software in 3 test situations: group 1, initial radiographic images of unfilled roots and images of fractured or non-fractured unfilled roots; group 2, initial radiographic images of unfilled roots and images of fractured or non-fractured filled roots; and group 3, initial radiographic images of filled roots and images of fractured or non-fractured filled roots. Three examiners evaluated all the original digital radiographs, as well as the subtracted images, for the presence or absence of VRFs. Numerical data were subject to statistical analysis with the use of receiver operator characteristic (ROC) curves. The areas under the ROC curve for groups 1, 2, and 3 were 0.86, 0.73, and 0.66, respectively. For the original digital radiographs, areas under the ROC curve were 0.80 (without gutta-percha) and 0.73 (with gutta-percha). No statistically significant differences were found between subtracted and original images. Digital subtraction radiography could be considered as an alternative tool for the investigation of VRFs because of its comparable diagnostic accuracy to existing methods. Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  2. Clinical applications of MR digital subtraction angiography for the evaluation of intracranial vascular and tumorous lesions

    Energy Technology Data Exchange (ETDEWEB)

    Katase, Shichiro; Tsuchiya, Kazuhiro; Hachiya, Junichi [Kyorin Univ., Mitaka, Tokyo (Japan). School of Medicine

    2001-07-01

    MR digital subtraction angiography (MR DSA), which is performed by a rapid two-dimensional T1-weighted sequence in combination with bolus injection of gadolinium-based contrast agent was applied to the evaluation of cerebral arteriovenous malformations (AVMs), brain tumors (intraaxial and extraaxial tumors), and other vascular lesions. This study was performed to evaluate the clinical usefulness of the method in the diagnosis of these lesions. We studied 19 cases of cerebral AVM, 36 cases of intraaxial tumor (metastatic brain tumors in 14, glioblastomas in five, astrocytomas in eight, malignant lymphomas in four, pineal tumors in two, and other tumors, in three), 34 cases of extraaxial tumor (meningiomas in 29, and pituitary adenomas in five), and 10 cases of other vascular lesions (cerebral aneurysms in five, venous thrombosis in two, and other lesion in three). For cerebral AVMs, the feeder, nidus, and drainer were evaluated on a 4 - point grading scale (0=poor, 1=fair, 2=good, 3=excellent), and the results obtained were compared with those of conventional cerebral angiography or MR angiography using the postcontrast three-dimensional time-of-flight method. Brain tumors were classified into six enhancement patterns, and were compared with the findings of conventional cerebral angiography. Other vascular lesions were assessed visually. All cases were evaluated independently by two radiologists, and inter-observer agreement was assessed using the {kappa}-test. In all cerebral AVM cases, the hemodynamics of the feeder, nidus, and drainer could be observed. In all but five brain tumor cases, tumor stain could be confirmed in MR DSA images. The findings of tumor stain corresponded to those of cerebral angiographic images. For other vascular lesions, results of lesion detection and lesion morphology were almost in congruence with other methods. MR DSA provides information on the hemodynamics of vascular and tumorous lesions. When used in conjunction with routine MR

  3. Two-dimensional thick-slice MR digital subtraction angiography for assessment of cerebrovascular occlusive diseases

    Energy Technology Data Exchange (ETDEWEB)

    Aoki, S.; Yoshikawa, T.; Hori, M.; Ishigame, K.; Nambu, A.; Kumagai, H.; Araki, T. [Dept. of Radiology, Yamanashi Medical Univ. (Japan)

    2000-12-01

    Although spatial resolution of current MR angiography is excellent, temporal resolution has remained unsatisfactory. We evaluated clinical applicability of 2D thick-slice, contrast-enhanced subtraction MR angiography (2D-MR digital subtraction angiography) with sub-second temporal resolution in cerebrovascular occlusive diseases. Twenty-five patients with cerebrovascular occlusive diseases (8 moyamoya diseases, 10 proximal internal carotid occlusions, and 2 sinus thromboses) were studied with a 1.5-T MR unit. The MR digital subtraction angiography (MRDSA) was performed per 0.97 s continuously just after a bolus injection of 15 ml of gadolinium chelates up to 40 s in sagittal (covering hemisphere) or coronal planes. Subtraction images were generated at a workstation. We evaluated imaging quality and hemodynamic information of MRDSA in comparison with those of routine MR imaging, non-contrast MR angiography, and X-ray intra-arterial DSA. Major cerebral arteries, all of the venous sinuses, and most tributaries were clearly visualized with 2D MRDSA. Also, pure arterial phases were obtained in all cases. The MRDSA technique demonstrated prolonged circulation in sinus thromboses, distal patent lumen of proximal occlusion, and some collateral circulation. Such hemodynamic information was comparable to that of intra-arterial DSA. Two-dimensional thick-slice MRDSA with high temporal resolution has a unique ability to demonstrate cerebral hemodynamics equivalent to that of intra-arterial DSA and may play an important role for evaluation of cerebrovascular occlusive diseases. (orig.)

  4. A feasibility study of projection-based energy weighting based on a photon-counting detector in contrast-enhanced digital subtraction mammography: A simulation study

    Science.gov (United States)

    Choi, Sunghoon; Lee, Seungwan; Choi, Yu-Na; Kim, Hee-Joung

    2014-06-01

    Contrast media, such as iodine and gadolinium, are generally used in digital subtraction mammography to enhance the contrast between target and background materials. In digital subtraction mammography, where one image (with contrast medium) is subtracted from another (anatomical background) to facilitate visualization of the tumor structure, tumors can be more easily distinguished after the injection of a contrast medium. In order to have more an effective method to increase the contrast-to-noise ratio (CNR), we applied a projection-based energy-weighting method. The purpose of this study is to demonstrate the feasibility of using the projection-based energy-weighting method in digital subtraction mammography. Unlike some other previous studies, we applied the projection-based energy-weighting method to more practical mammography conditions by using the Monte Carlo method to simulate four different iodine solutions embedded in a breast phantom comprised of 50% adipose and 50% glandular tissues. We also considered an optimal tube voltage and anode/filter combination in digital iodine contrast media mammography in order to maximize the figure-of-merit (FOM). The simulated source energy was from 20 to 45 keV to prevent electronic noise and include the k-edge energy of iodine (33.2 keV). The results showed that the projection-based energy-weighting improved the CNR by factors of 1.05-1.86 compared to the conventionally integrated images. Consequently, the CNR of digital subtraction mammography images can be improved by using projection-based energy-weighting with photon-counting detectors.

  5. Polishability and wear resistance of splint material for oral appliances produced with conventional, subtractive, and additive manufacturing.

    Science.gov (United States)

    Huettig, Fabian; Kustermann, Achim; Kuscu, Ebru; Geis-Gerstorfer, Jürgen; Spintzyk, Sebastian

    2017-07-14

    Occlusal splints to treat bruxism are commonly made from polymethylmethacrylate (PMMA) in a manual workflow (powder-liquid technique). Today digitalization allows a machine-based manufacturing in subtractive (milling) and additive (printing) means using industrial-made PMMA or comparable resins. An in-vitro study should assess the surface finish and screen the wear resistance of conventional and industrial materials. Therefore, a total of 30 specimens made from conventionally PMMA (group C; powder-liquid, Palapress), polycarbonate ingots (group S; innoBlanc splint plus), and light-curing resin (group A; VarseoWax splint) were polished to examine the surface roughness (Ra) by profilometry and further analyzed by SEM. The specimens were loaded with a steatite ball moving 5000 times along 1cm with 5N of surface pressure under constant wetting (artificial saliva). The total height of profile (Pt) was calculated by further profilometry of the specimens. All specimen showed initially comparable Ra values ranging between 0.06 and 0.05µm (SD = 0.01) after polishing. SEM investigations revealed no visual cues for scratches or irregularities in any group. After abrasion test, the comparison of the wear depths, revealed mean Pt values of 111.4µm (SD = 18.5) in C, 85.7µm (SD = 21.5) in S, and 99.1µm (SD = 21.5) in A, whereas the mean of S was statistically different from C (p = 0.025). No signs of abrasion were found on the steatite balls. All materials showed comparable polished surfaces and a similar scale of wear. It remains questionable if the detected statistical differences are of clinical relevance, but indicates the need for tests of novel materials, especially in additive manufacturing. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Strategies for Human Tumor Virus Discoveries: from Microscopic Observation to Digital Transcriptome Subtraction

    Directory of Open Access Journals (Sweden)

    Ezra David Mirvish

    2016-05-01

    Full Text Available Over 20% of human cancers worldwide are associated with infectious agents, including viruses, bacteria, and parasites. Various methods have been used to identify human tumor viruses, including electron microscopic observations of viral particles, immunologic screening, cDNA library screening, nucleic acid hybridization, consensus PCR, viral DNA array chip, and representational difference analysis (RDA. With the Human Genome Project, a large amount of genetic information from humans and other organisms has accumulated over the last decade. Utilizing the available genetic databases, Patrick S. Moore, Yuan Chang, and colleagues developed digital transcriptome subtraction (DTS, an in silico method to sequentially subtract human sequences from tissue or cellular transcriptome, and discovered Merkel cell polyomavirus (MCV from Merkel cell carcinoma (MCC. Here we review the background and methods underlying the human tumor virus discoveries and explain how DTS was developed and used for the discovery of MCV.

  7. Digital Subtraction Phonocardiography (DSP applied to the detection and characterization of heart murmurs

    Directory of Open Access Journals (Sweden)

    Ali Akbari Mohammad

    2011-12-01

    Full Text Available Abstract Background During the cardiac cycle, the heart normally produces repeatable physiological sounds. However, under pathologic conditions, such as with heart valve stenosis or a ventricular septal defect, blood flow turbulence leads to the production of additional sounds, called murmurs. Murmurs are random in nature, while the underlying heart sounds are not (being deterministic. Innovation We show that a new analytical technique, which we call Digital Subtraction Phonocardiography (DSP, can be used to separate the random murmur component of the phonocardiogram from the underlying deterministic heart sounds. Methods We digitally recorded the phonocardiogram from the anterior chest wall in 60 infants and adults using a high-speed USB interface and the program Gold Wave http://www.goldwave.com. The recordings included individuals with cardiac structural disease as well as recordings from normal individuals and from individuals with innocent heart murmurs. Digital Subtraction Analysis of the signal was performed using a custom computer program called Murmurgram. In essence, this program subtracts the recorded sound from two adjacent cardiac cycles to produce a difference signal, herein called a "murmurgram". Other software used included Spectrogram (Version 16, GoldWave (Version 5.55 as well as custom MATLAB code. Results Our preliminary data is presented as a series of eight cases. These cases show how advanced signal processing techniques can be used to separate heart sounds from murmurs. Note that these results are preliminary in that normal ranges for obtained test results have not yet been established. Conclusions Cardiac murmurs can be separated from underlying deterministic heart sounds using DSP. DSP has the potential to become a reliable and economical new diagnostic approach to screening for structural heart disease. However, DSP must be further evaluated in a large series of patients with well-characterized pathology to determine

  8. Digital Subtraction Phonocardiography (DSP) applied to the detection and characterization of heart murmurs.

    Science.gov (United States)

    Akbari, Mohammad Ali; Hassani, Kamran; Doyle, John D; Navidbakhsh, Mahdi; Sangargir, Maryam; Bajelani, Kourosh; Ahmadi, Zahra Sadat

    2011-12-20

    During the cardiac cycle, the heart normally produces repeatable physiological sounds. However, under pathologic conditions, such as with heart valve stenosis or a ventricular septal defect, blood flow turbulence leads to the production of additional sounds, called murmurs. Murmurs are random in nature, while the underlying heart sounds are not (being deterministic). We show that a new analytical technique, which we call Digital Subtraction Phonocardiography (DSP), can be used to separate the random murmur component of the phonocardiogram from the underlying deterministic heart sounds. We digitally recorded the phonocardiogram from the anterior chest wall in 60 infants and adults using a high-speed USB interface and the program Gold Wave http://www.goldwave.com. The recordings included individuals with cardiac structural disease as well as recordings from normal individuals and from individuals with innocent heart murmurs. Digital Subtraction Analysis of the signal was performed using a custom computer program called Murmurgram. In essence, this program subtracts the recorded sound from two adjacent cardiac cycles to produce a difference signal, herein called a "murmurgram". Other software used included Spectrogram (Version 16), GoldWave (Version 5.55) as well as custom MATLAB code. Our preliminary data is presented as a series of eight cases. These cases show how advanced signal processing techniques can be used to separate heart sounds from murmurs. Note that these results are preliminary in that normal ranges for obtained test results have not yet been established. Cardiac murmurs can be separated from underlying deterministic heart sounds using DSP. DSP has the potential to become a reliable and economical new diagnostic approach to screening for structural heart disease. However, DSP must be further evaluated in a large series of patients with well-characterized pathology to determine its clinical potential.

  9. Equilibrium radionuclide ventriculography: Comparison with echo-ventriculography and digital subtraction angiocardiography, evaluation of multiparameters

    Energy Technology Data Exchange (ETDEWEB)

    Hoer, G.; Standke, R.; Klepzig, H. Jr.; Maul, F.D.; Tuengerthal, S.; Tezak, S.; Reifarth, N.; Kanemoto, N.; Happ, J.; Baum, R.P.

    1986-09-01

    Subsequent to the discussion of technical prerequisites (fully-automated, reproducible multiparameter-analysis (MPA), rest, exercise) which is followed by remarks concerning the pathophysiology of ischemic left ventricular functional disorders in diastole and systole, the following points are considered: 1) comparative results of RNV, cineventriculoangiography, echo-ventriculography and intraveneous digital subtraction angiocardiography; 2) 'normal' values of RNV in MPA; 3) heart and pulmonary diseases (coronary artery disease with sensitivity and specificity of MPA), chronic obstructive pulmonary disease, chronic aortic insufficiency, hypertension; 4) summary of, and prospects for future potentialities (software, clinical indications).

  10. Role of digital tomosynthesis and dual energy subtraction digital radiography in detection of parenchymal lesions in active pulmonary tuberculosis

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Madhurima, E-mail: madhurimashrm88@gmail.com [Department of Radiodiagnosis and Imaging, PGIMER, Chandigarh 160012 (India); Sandhu, Manavjit Singh, E-mail: manavjitsandhu@yahoo.com [Department of Radiodiagnosis and Imaging, PGIMER, Chandigarh 160012 (India); Gorsi, Ujjwal, E-mail: ujjwalgorsi@gmail.com [Department of Radiodiagnosis and Imaging, PGIMER, Chandigarh 160012 (India); Gupta, Dheeraj, E-mail: dheeraj1910@gmail.com [Department of Pulmonary Medicine, PGIMER, Chandigarh 160012 (India); Khandelwal, Niranjan, E-mail: khandelwaln@hotmail.com [Department of Radiodiagnosis and Imaging, PGIMER, Chandigarh 160012 (India)

    2015-09-15

    Highlights: • Digital tomosynthesis and dual energy subtraction digital radiography are modifications of digital radiography. • These modalities perform better than digital radiography in detection of parenchymal lesions in active pulmonary tuberculosis. • Digital tomosynthesis has a sensitivity of 100% in detection of cavities. • Centrilobular nodules seen on CT in active pulmonary tuberculosis, were also demonstrated on digital tomosynthesis in our study. • Digital tomosynthesis can be used for diagnosis and follow up of patients in pulmonary tuberculosis, thereby reducing the number of CT examinations. - Abstract: Objective: To assess the role of digital tomosynthesis (DTS) and dual energy subtraction digital radiography (DES-DR) in detection of parenchymal lesions in active pulmonary tuberculosis (TB) and to compare them with digital radiography (DR). Materials and methods: This prospective study was approved by our institutional review committee. DTS and DES-DR were performed in 62 patients with active pulmonary TB within one week of multidetector computed tomography (MDCT) study. Findings of active pulmonary TB, that is consolidation, cavitation and nodules were noted on digital radiography (DR), DTS and DES-DR in all patients. Sensitivity, specificity, positive and negative predictive values of all 3 modalities was calculated with MDCT as reference standard. In addition presence of centrilobular nodules was also noted on DTS. Results: Our study comprised of 62 patients (33 males, 29 females with age range 18–82 years). Sensitivity and specificity of DTS for detection of nodules and cavitation was better than DR and DES-DR. Sensitivity and specificity of DTS for detection of consolidation was comparable to DR and DES-DR. DES-DR performed better than DR in detection of nodules and cavitation. DTS was also able to detect centrilobular nodules with sensitivity and specificity of 57.4% and 86.5% respectively. Conclusion: DTS and DES-DR perform better

  11. Assessment of vasospasm in experimental subarachnoid hemorrhage in rats by selective biplane digital subtraction angiography

    Energy Technology Data Exchange (ETDEWEB)

    Weidauer, Stefan; Dettmann, Edgar; Zanella, Friedhelm E. [University of Frankfurt, Institute of Neuroradiology, Frankfurt (Germany); Vatter, Hartmut; Seifert, Volker [University of Frankfurt, Clinic of Neurosurgery, Frankfurt (Germany)

    2006-03-15

    Although the rat subarachnoid hemorrhage model is well established in vasospasm research, the angiographic evaluation is difficult due to the animal's small size. For this reason, the aim of the study was to develop a standardized angiographic examination technique without additional complex equipment. Under general anesthesia, 11 Sprague-Dawley rats underwent selective cerebral digital subtraction angiography using a 0.3 mm focal spot and a 2.0-fold linear magnification. Five animals had experimental subarachnoid hemorrhage according to the ''double-hemorrhage'' model. Comparison with the intraarterial tip of the microcatheter enabled calibration of the vessel lumen. The diameter of the normal basilar artery (n=6) was 0.34{+-}0.03 mm (mean{+-}SD), whereas delayed vasospastic constriction (mean 6.2 days) caused a reduction in diameter of 32.4% (0.23{+-}0.09 mm) as well as impaired collateral blood flow via the posterior communicating artery and anterior spinal artery. Histological examination of sections stained with hematoxylin and eosin under a light microscope confirmed vasospasm. In conclusion, biplane digital subtraction angiography allows precise and reliable evaluation of arterial diameter reduction and hemodynamic parameters in a rat vasospasm model. However, further investigation is required for assessment of vasoactive drugs, e.g., endothelin receptor antagonists. (orig.)

  12. Comparison of the diagnostic accuracy of direct digital radiography system, filtered images, and subtraction radiography

    Directory of Open Access Journals (Sweden)

    Wilton Mitsunari Takeshita

    2013-01-01

    Full Text Available Background: To compare the diagnostic accuracy of three different imaging systems: Direct digital radiography system (DDR-CMOS, four types of filtered images, and a priori and a posteriori registration of digital subtraction radiography (DSR in the diagnosis of proximal defects. Materials and Methods: The teeth were arranged in pairs in 10 blocks of vinyl polysiloxane, and proximal defects were performed with drills of 0.25, 0.5, and 1 mm diameter. Kodak RVG 6100 sensor was used to capture the images. A posteriori DSR registrations were done with Regeemy 0.2.43 and subtraction with Image Tool 3.0. Filtered images were obtained with Kodak Dental Imaging 6.1 software. Images (n = 360 were evaluated by three raters, all experts in dental radiology. Results: Sensitivity and specificity of the area under the receiver operator characteristic (ROC curve (Az were higher for DSR images with all three drills (Az = 0.896, 0.979, and 1.000 for drills 0.25, 0.5, and 1 mm, respectively. The highest values were found for 1-mm drills and the lowest for 0.25-mm drills, with negative filter having the lowest values of all (Az = 0.631. Conclusion: The best method of diagnosis was by using a DSR. The negative filter obtained the worst results. Larger drills showed the highest sensitivity and specificity values of the area under the ROC curve.

  13. Carbon dioxide digital subtraction angiography in percutaneous sclerotherapy of venous hemangiomas

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jae Hyung; Chung, Jin Wook; Kang, Heung Sik; Han, Man Chung [Seoul National Univ. College of Medicine, Seoul (Korea, Republic of)

    1997-08-01

    To investigate the usefulness of carbon dioxide digital subtraction angiography (CO{sub 2}-DSA) in direct puncture sclerotherapy of venous hemangiomas involving extremities. Direct puncture sclerotherapy was performed in 12 patients with venous hemangioma of extremities. After direct puncture of the venous hemangiomas, 30-50cc of CO{sub 2} was manually injected and digital subtraction angiograms were obtained. If draining vein was visualized, a tourniquet was applied at the proximal site to compress the draining veins. Thereafter, radiopaque embolic materials such as 1:3 mixture of Lipiodol and absolute ethanol or ethanolamine oleate-Lipiodol-Avitene(microfibrillar collagen hemostat) mixture were slowly injected under the fluoroscopic guidance. Rapid injection of large amount of CO{sub 2} enabled the visualization of wide areas of venous hemangiomas in 11 patients. Draining veins were reliably demonstrated in 10 patients and pulmonary embolism of embolic materials was effectively prevented by proximal tourniquet application. Because of radiolucent nature of CO{sub 2} retained in hemangiomas, we could clearly identify the distribution of radiopaque embolic materials under fluoroscopy. Retained CO{sub 2} also could be used as a guide for additional multiple puncture of hemangiomas. There was no systemic symptoms or complications related to CO{sub 2}-DSA. CO{sub 2}-DSA is a convenient, safe and useful angiographic technique in direct puncture sclerotherapy of hemangiomas involving extremities.

  14. Novel method for digital subtraction of tagged stool in virtual colonoscopy

    Science.gov (United States)

    Guendel, Lutz; Suehling, Michael; Eckert, Helmut

    2008-03-01

    Colon cancer is one of the most frequent causes of death. CT colonography is a novel method for the detection of polyps and early cancer. The general principle of CT colonography includes a cathartic bowel preparation. The resulting discomfort for patients leads to limited patient acceptance and therefore to limited cancer detection rates. Reduced bowel preparation, techniques for stool tagging, and electronic cleansing, however, improve the acceptance rates. Hereby, the high density of oral contrast material highlights residual stool and can be digitally removed. Known subtraction methods cause artifacts: additional 3D objects are introduced and small bowel folds are perforated. We propose a new algorithm that is based on the 2 nd derivative of the image data using the Hessian matrix and the following principal axis transform to detect tiny folds which shall not be subtracted together with tagged stool found by a thresholding method. Since the stool is usually not homogenously tagged with contrast media a detection algorithm for island-like structures is incorporated. The interfaces of air-stool level and colon wall are detected by a 3-dimensional difference of Gaussian module. A 3-dimensional filter smoothes the transitions between removed stool and colon tissue. We evaluated the efficacy of the new algorithm with 10 patient data sets. The results showed no introduced artificial objects and no perforated folds. The artifacts at the air-stool and colon tissue-stool transitions are considerably reduced compared to those known from the literature.

  15. Quantitative digital subtraction radiography for assessment of bone density changes following periodontal guided tissue regeneration.

    Science.gov (United States)

    Christgau, M; Wenzel, A; Hiller, K A; Schmalz, G

    1996-01-01

    The quantitative assessment of alveolar bone density changes in periodontal defects following guided tissue regeneration (GTR). Twelve patients with 30 intrabony lesions and 16 furcation defects took part. Standardized radiographic and clinical examinations were carried out immediately before and then 5 and 13 months after surgery. Intra-oral radiographs were evaluated by means of digital subtraction radiography (DSR). Within the subtraction images, a window ('experimental region') was defined covering the visible density changes in the defect area. Background noise was measured by using a similarly sized window ('control region') located in an area not affected by GTR. Bone density changes were quantitatively evaluated by calculation of the mean, standard deviation and maximum and minimum values of the grey-level histogram within these windows. DSR revealed significant bone density gain after GTR in intrabony and furcation defects. While a continuous increase was observed over the 13 month period in intrabony defects, changes in furcation defects occurred mostly in the 5-13 month period. Clinically, a distinct vertical and horizontal attachment gain was found. The correlation coefficients between changes in radiographic density and clinical parameters were low, indicating a difference in the information obtained by the two diagnostic methods. Quantitative DSR is a valuable, non-invasive, objective method to obtain information on density changes in intrabony and furcation defects treated by GTR. However, a full assessment of soft and hard tissue changes requires both clinical evaluation and DSR.

  16. Three-dimensional digital subtraction angiography vs two-dimensional digital subtraction angiography for detection of ruptured intracranial aneurysms: A study of 86 aneurysms

    Directory of Open Access Journals (Sweden)

    Kawashima Masatou

    2005-01-01

    Full Text Available Aims : Three-dimensional reconstruction of intracranial vessels is of interest for evaluation of aneurysms. This study determined diagnostic difference of three-dimensional digital subtraction angiography (3D-DSA, volume-rendering image versus 2D-DSA for evaluating ruptured intracranial aneurysms, particularly focusing on the size of aneurysms as depicted in both images. Settings and Design : Sixty-nine patients underwent 3D-DSA and 2D-DSA. The relative size of an aneurysm, which is the ratio of the maximal diameter of an aneurysm to the diameter of a major vessel, was compared between imaging techniques. In addition, relative sizes of smaller aneurysms (10 mm. Statistical analysis used : For comparison of aneurysm size and location of aneurysm, statistical analysis was performed with the Yates chi square test; statistical significance was set with a P value of less than 0.05. Results: Sixty-three (73.3% of the 86 total aneurysms were bigger when measured with 3D-DSA versus 2D-DSA. When measured with 3D-DSA, 28 (84.8% of the 33 smaller aneurysms were bigger, and 50% of the larger aneurysms were bigger versus measurements of 2D-DSA images ( P P Conclusions : 3D-DSA, especially volume-rendering images, tends to depict ruptured intracranial aneurysms bigger than 2D-DSA. This is particularly true with cerebral aneurysms that are <5 mm in size and are located in the anterior circulation, especially ICA and ACA territories.

  17. [Affine transformation-based automatic registration for peripheral digital subtraction angiography (DSA)].

    Science.gov (United States)

    Kong, Gang; Dai, Dao-Qing; Zou, Lu-Min

    2008-07-01

    In order to remove the artifacts of peripheral digital subtraction angiography (DSA), an affine transformation-based automatic image registration algorithm is introduced here. The whole process is described as follows: First, rectangle feature templates are constructed with their centers of the extracted Harris corners in the mask, and motion vectors of the central feature points are estimated using template matching technology with the similarity measure of maximum histogram energy. And then the optimal parameters of the affine transformation are calculated with the matrix singular value decomposition (SVD) method. Finally, bilinear intensity interpolation is taken to the mask according to the specific affine transformation. More than 30 peripheral DSA registrations are performed with the presented algorithm, and as the result, moving artifacts of the images are removed with sub-pixel precision, and the time consumption is less enough to satisfy the clinical requirements. Experimental results show the efficiency and robustness of the algorithm.

  18. Idiopathic Thrombus in the Common Carotid Artery on Digital Subtraction Angiography

    Directory of Open Access Journals (Sweden)

    Anand Alurkar

    2012-01-01

    Full Text Available In the present study, we discuss the accuracy of digital subtraction angiography (DSA in diagnosis of thrombus in the common carotid artery and its role in the medical management of this disorder. Between 2006 and 2011, four patients (age group ranging from 26 to 48 years presented to our institution with symptoms of stroke. DSA in all these patients showed cigar-shaped filling defect in the common carotid artery. All the patients were managed successfully with anticoagulation treatment. Follow-up Duplex scan was done in all the patients. DSA is the gold standard to diagnose free floating thrombus in the common carotid artery. Medical management can be effective in these patients but a multidisciplinary team approach is needed for appropriate management.

  19. The use of neurovascular ultrasound versus digital subtraction angiography in acute ischemic stroke

    Directory of Open Access Journals (Sweden)

    Marcos C. Lange

    2015-03-01

    Full Text Available Cervical and intracranial arterial evaluation is an important issue for acute ischemic stroke (IS. Objective Compare the use of the neurovascular ultrasound examination (NVUE to digital subtraction angiography (DSA in acute IS patients for diagnosing significant extracranial and intracranial arteriopathy. Method Nonconsecutive patients with IS or transient ischemic attack admitted within 12 hours of the onset of symptoms were evaluated retrospectively. Standardized NVUE and DSA were done in all patients within the first 120 hours of hospital admission. Results Twenty-four patients were included in the study. Compared to DSA, the NVUE demonstrated 94.7% sensitivity and 100% specificity for identifying symptomatic extracranial and/or intracranial arteriopathy. Conclusion The standardized NVUE technique demonstrated high sensitivity and specificity compared to DSA for diagnosing arterial abnormalities in acute IS patients.

  20. Effectiveness of digital subtraction radiography in detecting artificially created osteophytes and erosions in the temporomandibular joint

    Energy Technology Data Exchange (ETDEWEB)

    Kocasarac, Husniye Demirturk [Dept. of Comprehensive Dentistry, The University of Texas Health Science Center, San Antonio (United States); Celenk, Peruze [Dept. of Oral and Maxillofacial Radiology, Faculty of Dentistry, Ondokuz Mayis University, Samsun (Turkmenistan)

    2017-06-15

    Erosions and osteophytes are radiographic characteristics that are found in different stages of temporomandibular joint (TMJ) osteoarthritis. This study assessed the effectiveness of digital subtraction radiography (DSR) in diagnosing simulated osteophytes and erosions in the TMJ. Five intact, dry human skulls were used to assess the effectiveness of DSR in detecting osteophytes. Four cortical bone chips of varying thicknesses (0.5 mm, 1.0 mm, 1.5 mm, and 2.0 mm) were placed at the medial, central, and lateral aspects of the condyle anterior surface. Two defects of varying depth (1.0 mm and 1.5 mm) were created on the lateral, central, and medial poles of the condyles of 2 skulls to simulate erosions. Panoramic images of the condyles were acquired before and after artificially creating the changes. Digital subtraction was performed with Emago dental image archiving software. Five observers familiar with the interpretation of TMJ radiographs evaluated the images. Receiver operating characteristic (ROC) analysis was used to evaluate the diagnostic accuracy of the imaging methods. The area under the ROC curve (Az) value for the overall diagnostic accuracy of DSR in detecting osteophytic changes was 0.931. The Az value for the overall diagnostic accuracy of panoramic imaging was 0.695. The accuracy of DSR in detecting erosive changes was 0.854 and 0.696 for panoramic imaging. DSR was remarkably more accurate than panoramic imaging in detecting simulated osteophytic and erosive changes. The accuracy of panoramic imaging in detecting degenerative changes was significantly lower than the accuracy of DSR (P<.05). DSR improved the accuracy of detection using panoramic images.

  1. Pilot study: digital subtraction radiography as a tool to assess alveolar bone changes in periodontitis patients under treatment with subantimicrobial doses of doxycycline

    NARCIS (Netherlands)

    A.D. Goren; S.M. Dunn; M. Wolff; P.F. van der Stelt; D.C. Colosi; L.M. Golub

    2008-01-01

    Background Subtle changes in marginal alveolar bone level can be demonstrated using digital subtraction of sequential radiographs. Objective We aimed to evaluate the practical application of geometrically corrected digital subtraction in a clinical study of alveolar bone response to a drug previousl

  2. Evaluation of chronic periapical lesions by digital subtraction radiography by using Adobe Photoshop CS: a technical report.

    Science.gov (United States)

    Carvalho, Fabiola B; Gonçalves, Marcelo; Tanomaru-Filho, Mário

    2007-04-01

    The purpose of this study was to describe a new technique by using Adobe Photoshop CS (San Jose, CA) image-analysis software to evaluate the radiographic changes of chronic periapical lesions after root canal treatment by digital subtraction radiography. Thirteen upper anterior human teeth with pulp necrosis and radiographic image of chronic periapical lesion were endodontically treated and radiographed 0, 2, 4, and 6 months after root canal treatment by using a film holder. The radiographic films were automatically developed and digitized. The radiographic images taken 0, 2, 4, and 6 months after root canal therapy were submitted to digital subtraction in pairs (0 and 2 months, 2 and 4 months, and 4 and 6 months) choosing "image," "calculation," "subtract," and "new document" tools from Adobe Photoshop CS image-analysis software toolbar. The resulting images showed areas of periapical healing in all cases. According to this methodology, the healing or expansion of periapical lesions can be evaluated by means of digital subtraction radiography by using Adobe Photoshop CS software.

  3. A digital subtraction radiography based tool for periodontal bone resorption analysis

    Energy Technology Data Exchange (ETDEWEB)

    Schiabel, Homero; Rodrigues, Eveline B., E-mail: homero@sc.usp.br [University of Sao Paulo (EESC/USP), Sao Carlos, SP (Brazil). Dept. of Electrical Engineering; Rubira-Bullen, Izabel R.F. [University of Sao Paulo (USP), Bauru, SP (Brazil). Bauru Dentistry School

    2011-07-01

    The aim of this paper was to describe an aided diagnosis scheme for periodontal bone resorption so that the dentist can make an early diagnosis of the periodontal disease and establish the best treatment plan to increase the success of healing. Three ways of displaying the results are provided: qualitative, simple quantitative and colored-percentage quantitative views. A total of 72 pairs of in vitro radiographic images were used. The main procedure registers the images perspective projection aimed to align them in rotation and translation, and is followed by the application of a contrast correction technique. The results from the subtraction were evaluated firstly by the comparison between the actual and the digital sizes corresponding to the holes made by drills in phantoms. The mean error was 4.2%. The method was also applied to actual tooth radiographic images and could detect clearly the effect of treatment of periodontal diseases. It is dependent on the reproducibility of the process of radiographs acquisition and digitization, but the calculated mean error allows to conclude its better efficacy compared to usual procedures in this field. (author)

  4. Intravenous digital subtraction angiography in the assessment of patients with left to right shunts before and after surgical correction

    Energy Technology Data Exchange (ETDEWEB)

    Yiannikas, J.; Moodie, D.S.; Gill, C.C.; Sterba, R.; McIntyre, R.; Buonocore, E.

    1984-06-01

    Pre- and postoperative structural changes and pulmonary to systemic flow (QP/QS) ratios were assessed using digital angiography in 34 patients documented to have a left to right shunt at cardiac catheterization. There were 16 men and 18 women whose ages ranged from 4 months to 60 years. The radiographic single mask mode was used for all digital subtraction angiographic studies with a typical radiographic sequence being 80 to 100 kV, 5 to 10 mA/frame at six frames/s for 15 seconds. Renografin-76 was used as a bolus injection at 0.5 to 1.0 ml/kg via an arm vein in most patients. The level of the left to right shunt and any associated anomalies were noted and compared with results from cardiac catheterization. Digital subtraction angiographic flow curves were generated from the pulmonary arteries, and QP/QS ratios were calculated pre- and postoperatively using the gamma variate fit method and compared with the QP/QS ratio from first pass radionuclide studies. A strong correlation between preoperative digital subtraction angiographically derived QP/QS ratio and radionuclide-derived QP/QS ratio was found, with an r value equal to 0.89, p less than 0.0001. Postoperatively, all patients had a QP/QS ratio less than 1.2:1.0 for both digital subtraction angiography and radionuclide studies. The level of left to right shunt was accurately assessed in all patients, and its absence observed postoperatively. Associated anomalies, such as a persistent left superior vena cava, coarctation of the aorta and partial anomalous venous return, were identified in all cases.

  5. K-edge digital subtraction imaging with dichromatic x-ray sources: SNR and dose studies

    Science.gov (United States)

    Sarnelli, A.; Elleaume, H.; Taibi, A.; Gambaccini, M.; Bravin, A.

    2006-09-01

    The aim of the present work is to analytically evaluate the signal to noise ratio (SNR) and the delivered dose in K-edge digital subtraction imaging (KES) using two types of x-ray sources: a monochromatic x-ray source (available at synchrotron radiation facilities and considered as gold standard) and a quasi-monochromatic compact source. The energy separation ΔE between the two monochromatic beams is 1 keV and 4 keV for the two sources, respectively. The evaluation has been performed for both radiography and computed tomography. Different geometries have been studied to mimic clinical situations. In mammography, a pathology perfused by a contrast agent has been modelled; in angiography, a vessel superimposed to a ventricle or a stand-alone artery stenosis has been studied. The SNR and the skin dose have been calculated as a function of the detail diameter, the contrast agent (iodine and gadolinium), and its concentration in the tissues. Results show that for ΔE = 4 keV a slightly higher delivered dose is required to obtain the same SNR with respect to ΔE < 1 keV. A similar study has been performed for KES-CT. Computer simulations of CT images performed with Snark software are shown to validate the analytical calculations.

  6. Predictive value of digital subtraction angiography in patients with tuberculous meningitis

    Energy Technology Data Exchange (ETDEWEB)

    Rojas-Echeverri, L.A. [Dept. of Neuroimaging and Endovascular Therapy, National Inst. for Neurology and Neurosurgery, Mexico City (Mexico); Soto-Hernandez, J.L. [Infectious Disease Dept., National Inst. for Neurology and Neurosurgery, Tlalpan (Mexico); Garza, S. [Div. of Neurology, National Inst. for Neurology and Neurosurgery, Tlalpan (Mexico); Martinez-Zubieta, R. [Div. of Neurology, National Inst. for Neurology and Neurosurgery, Tlalpan (Mexico); Miranda, L.I. [Div. of Neurology, National Inst. for Neurology and Neurosurgery, Tlalpan (Mexico); Garcia-Ramos, G. [Div. of Neurology, National Inst. for Neurology and Neurosurgery, Tlalpan (Mexico); Zenteno, M. [Dept. of Neuroimaging and Endovascular Therapy, National Inst. for Neurology and Neurosurgery, Mexico City (Mexico)

    1996-01-01

    Digital subtraction angiography (DSA) was performed in 24 adults with tuberculous meningitis (TBM) and results were correlated with 24 admission and 16 follow-up CT examinations. 19 MRI studies and clinical outcome at a mean follow-up of 44 weeks. DSA was abnormal in 11 patients. Abnormal DSA was associated with advenced clinical stages of the Medical Research Council classification, admission CT with hydrocephalus or gyral cortical enhancement. MRI disclosed brain infarcts not seen on initial CT in 8 cases. Of seven patients who died, 4 had abnormal and 3 normal DSA. Among patients who survived, those with normal DSA had a better functional outcome by Karnofsky scores. During follow-up infarcts were evident in 16 patients. Abnormal DSA in relation to brain infarcts had a sensitivity of 0.56, specificity 0.75, positive predictive value 0.82 and negative predictive value 0.46. A single arteriogram does not predict the outcome in patients with TBM and its value is limited in the assessment of vascular complications of TBM. Angiography in TBM is justified only in specific clinical trials to assess new therapeutic modalities against infarcts. (orig.)

  7. 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.)

  8. Blood flow measurement using digital subtraction angiography for assessing hemodialysis access function

    Science.gov (United States)

    Koirala, Nischal; Setser, Randolph M.; Bullen, Jennifer; McLennan, Gordon

    2017-03-01

    Blood flow rate is a critical parameter for diagnosing dialysis access function during fistulography where a flow rate of 600 ml/min in arteriovenous graft or 400-500 ml/min in arteriovenous fistula is considered the clinical threshold for fully functioning access. In this study, a flow rate computational model for calculating intra-access flow to evaluate dialysis access patency was developed and validated in an in vitro set up using digital subtraction angiography. Flow rates were computed by tracking the bolus through two regions of interest using cross correlation (XCOR) and mean arrival time (MAT) algorithms, and correlated versus an in-line transonic flow meter measurement. The mean difference (mean +/- standard deviation) between XCOR and in-line flow measurements for in vitro setup at 3, 6, 7.5 and 10 frames/s was 118+/-63 37+/-59 31+/-31 and 46+/-57 ml/min respectively while for MAT method it was 86+/-56 57+/-72 35+/-85 and 19+/-129 ml/min respectively. The result of this investigation will be helpful for selecting candidate algorithms while blood flow computational tool is developed for clinical application.

  9. Patient radiation dose from computed tomography angiography and digital subtraction angiography of the brain

    Science.gov (United States)

    Netwong, Y.; Krisanachinda, A.

    2016-03-01

    The 64-row multidetector computed tomography angiography (64-MDCTA) provides vascular image quality of the brain similar to digital subtraction angiography (DSA), but the effective dose of CTA is lower than DSA studied in phantom. The purpose of this study is to evaluate the effective dose from 64-MDCTA and DSA. Effective dose (according to ICRP 103) from 64-MDCTA and DSA flat panel detector for cerebral vessels examination of the brain using standard protocols as recommended by the manufacturer was calculated for 30 cases of MDCTA (15 male and 15 female).The mean patient age was 49.5 (23-89) yrs. 30 cases of DSA (14 male and 16 female), the mean patient age was 46.8 (21-81) yrs. For CTA, the mean effective dose was 3.7 (2.82- 5.19) mSv. For DSA, the mean effective dose was 5.78 (3.3-10.06) mSv. The effective dose of CTA depends on the scanning protocol and scan length. Low tube current can reduce patient dose whereas the number of exposures and number of series in 3D rotational angiography (3D RA) resulted in increasing effective dose in DSA patients.

  10. Clinical application of dynamic digital subtraction angiography in cerebrovascular ischemic diseases

    Energy Technology Data Exchange (ETDEWEB)

    Hirata, Yoshifumi; Nonaka, Nobuhito; Matsukado, Yasuhiko; Takahashi, Mutsumasa.

    1987-09-01

    Dynamic intravenous digital subtraction angiography (IV-DSA) was performed in 37 patients with cerebrovascular ischemic diseases. The time density curve of IV-DSA was analysed, and peak time, mean transit time and mode of transit time were obtained in each patient. On the basis of these values, cerebral perfusion was classified into low, normal and high perfusion patterns. Normal perfusion pattern was noted in 40% of patients with transient ischemic attack (TIA) and 7 % of patients with cerebral infarction. Low perfusion pattern was observed in 60 % of patients with TIA and 87 % of patients with cerebral infarction. High perfusion pattern was encountered only in 7 % of patients with cerebral infarction. In ischemic patients with moyamoya disease, extremely prolonged cerebral circulation time was evidenced by the presence of a flat or uphill type of the time density curve. This finding well correlated with decreased cerebral blood flow on single photon emission tomography. These findings suggest that the analysis of dynamic DSA is very important and useful in the clinical evaluation of patients with cerebrovascular ischemic diseases.

  11. Remapping of digital subtraction angiography on a standard fluoroscopy system using 2D-3D registration

    Science.gov (United States)

    Alhrishy, Mazen G.; Varnavas, Andreas; Guyot, Alexis; Carrell, Tom; King, Andrew; Penney, Graeme

    2015-03-01

    Fluoroscopy-guided endovascular interventions are being performing for more and more complex cases with longer screening times. However, X-ray is much better at visualizing interventional devices and dense structures compared to vasculature. To visualise vasculature, angiography screening is essential but requires the use of iodinated contrast medium (ICM) which is nephrotoxic. Acute kidney injury is the main life-threatening complication of ICM. Digital subtraction angiography (DSA) is also often a major contributor to overall patient radiation dose (81% reported). Furthermore, a DSA image is only valid for the current interventional view and not the new view once the C-arm is moved. In this paper, we propose the use of 2D-3D image registration between intraoperative images and the preoperative CT volume to facilitate DSA remapping using a standard fluoroscopy system. This allows repeated ICM-free DSA and has the potential to enable a reduction in ICM usage and radiation dose. Experiments were carried out using 9 clinical datasets. In total, 41 DSA images were remapped. For each dataset, the maximum and averaged remapping accuracy error were calculated and presented. Numerical results showed an overall averaged error of 2.50 mm, with 7 patients scoring averaged errors < 3 mm and 2 patients < 6 mm.

  12. [Digital subtraction angiography with carbon dioxide in severe arterial ischemia and allergy to iodinated compounds].

    Science.gov (United States)

    Calvo Cascallo, J; Mundi Salvadó, N; Cardona Fontanet, M

    1993-01-01

    When in some selected patients, a direct arterial surgery (DAS) procedure or an endoluminal surgery (ES) are required for a chronic arterial ischemia (III or IV degrees), and an arteriography with contrast is absolutely contraindicated (because of severe renal failure without hemodialysis program or a severe congestive heart failure or a hyperthyroidism or a seriously demonstrated hypersensibility against the contrast agents); an angiography by digital subtraction with carbon dioxide (DIVAS-CO2) is indicated. This technique provides good quality images with minimal risks for the patient and an adequate study for ulterior treatment. We report a case of a 67-years-old woman, with diabetes-II, ischemic cardiopathy, arterial hypertension and a demonstrated hypersensibility against the iodide compounds. The patient was admitted because of a chronic ischemia (IV degree) with ischemic ulcerations on some fingers from the left foot. High doses of analgesic drugs were needed. Because the hypersensibility against the iodide compounds, an angiography with CO2 was carried out. The good quality images provided by this technique showed the factibility of a revascularization.

  13. A LabVIEW Platform for Preclinical Imaging Using Digital Subtraction Angiography and Micro-CT.

    Science.gov (United States)

    Badea, Cristian T; Hedlund, Laurence W; Johnson, G Allan

    2013-01-01

    CT and digital subtraction angiography (DSA) are ubiquitous in the clinic. Their preclinical equivalents are valuable imaging methods for studying disease models and treatment. We have developed a dual source/detector X-ray imaging system that we have used for both micro-CT and DSA studies in rodents. The control of such a complex imaging system requires substantial software development for which we use the graphical language LabVIEW (National Instruments, Austin, TX, USA). This paper focuses on a LabVIEW platform that we have developed to enable anatomical and functional imaging with micro-CT and DSA. Our LabVIEW applications integrate and control all the elements of our system including a dual source/detector X-ray system, a mechanical ventilator, a physiological monitor, and a power microinjector for the vascular delivery of X-ray contrast agents. Various applications allow cardiac- and respiratory-gated acquisitions for both DSA and micro-CT studies. Our results illustrate the application of DSA for cardiopulmonary studies and vascular imaging of the liver and coronary arteries. We also show how DSA can be used for functional imaging of the kidney. Finally, the power of 4D micro-CT imaging using both prospective and retrospective gating is shown for cardiac imaging.

  14. Analysis of the venous channel within the clivus using multidetector computed tomography digital subtraction venography.

    Science.gov (United States)

    Mizutani, Katsuhiro; Toda, Masahiro; Kurasawa, Jun; Akiyama, Takenori; Fujiwara, Hirokazu; Jinzaki, Masahiro; Yoshida, Kazunari

    2017-03-01

    Although neuroradiologists and skull base neurosurgeons are aware of the existence of veins within the clivus, such vessels have seldom been described in the literature. The aim of the present study is to elucidate the detailed venous structure of the clivus. Computed tomography digital subtraction venography (CT-DSV) images of 50 unruptured aneurysm cases were examined retrospectively. Eighteen emissary veins were identified in 14 (28.0%) cases. A half of the emissary veins connected the inferior petrosal sinus with the inferior petro-occipital vein (IPOV) in the middle clivus. The clival diploic vein (CDV) was identified in 14.0% of cases, 42.9% of which had the clivus of the presellar type. The CDV was connected to the posterior intercavernous sinus or the rostral end of the basilar plexus superiorly, and was connected to the IPOV, anterior condylar vein, marginal sinus, or the anterior condylar confluence. The CDV provides collateral channels between the cavernous sinus and the internal jugular vein and the inferior petrosal sinus and the IPOV. Understanding of the emissary veins in the clivus and the CDV is valuable for skull base surgery, especially for endonasal endoscopic skull base procedures.

  15. In vivo small-animal imaging using micro-CT and digital subtraction angiography

    Energy Technology Data Exchange (ETDEWEB)

    Badea, C T; Johnson, G A [Center for In Vivo Microscopy, Department of Radiology, Duke University, Durham, NC 27710 (United States); Drangova, M; Holdsworth, D W [Imaging Research Laboratories, Robarts Research Institute, University of Western Ontario, London, ON N6A 5K8 (United States)], E-mail: Cristian.Badea@duke.edu

    2008-10-07

    Small-animal imaging has a critical role in phenotyping, drug discovery and in providing a basic understanding of mechanisms of disease. Translating imaging methods from humans to small animals is not an easy task. The purpose of this work is to review in vivo x-ray based small-animal imaging, with a focus on in vivo micro-computed tomography (micro-CT) and digital subtraction angiography (DSA). We present the principles, technologies, image quality parameters and types of applications. We show that both methods can be used not only to provide morphological, but also functional information, such as cardiac function estimation or perfusion. Compared to other modalities, x-ray based imaging is usually regarded as being able to provide higher throughput at lower cost and adequate resolution. The limitations are usually associated with the relatively poor contrast mechanisms and potential radiation damage due to ionizing radiation, although the use of contrast agents and careful design of studies can address these limitations. We hope that the information will effectively address how x-ray based imaging can be exploited for successful in vivo preclinical imaging. (topical reviews)

  16. The comparative study on diagnostic validity of cerebral aneurysm by computed tomography angiography versus digital subtraction angiography after subarachnoid hemorrhage

    Directory of Open Access Journals (Sweden)

    Masih Saboori

    2011-01-01

    Full Text Available Background: In order to declare the preoperative diagnostic value of brain aneurysms, two radiological modalities, computed tomographic angiography and digital subtraction angiography were compared. Methods: In this descriptive analytic study, diagnostic value of computed tomographic angiography (CTA was com-pared with digital subtraction angiography (DSA. Sensitivity, specificity, positive and negative predictive values were calculated and compared between the two modalities. All data were analyzed with SPSS software, version 16. Results: Mean age of patients was 49.5 ± 9.13 years. 57.9 % of subjects were female. CTA showed 89% sensitivity and 100% specificity whereas DSA demonstrated 74% sensitivity and 100% specificity. Positive predictive value of both methods was 100%, but negative predictive value of CTA and DSA was 85% and 69%, respectively. Conclusions: Based on our data, CTA is a valuable diagnostic modality for detection of brain aneurysm and su-barachnoid hemorrhage.

  17. Multi-section CT angiography compared with digital subtraction angiography in diagnosing major arterial hemorrhage in inflammatory pancreatic disease

    Energy Technology Data Exchange (ETDEWEB)

    Hyare, Harpreet [Department of Imaging, University College London Hospitals NHS Foundation Trust, University College Hospital, 235 Euston Road, London NW1 2BU (United Kingdom)]. E-mail: hhyare@doctors.org.uk; Desigan, Sharmini [Department of Imaging, University College London Hospitals NHS Foundation Trust, University College Hospital, 235 Euston Road, London NW1 2BU (United Kingdom); Nicholl, Helen [Department of Imaging, University College London Hospitals NHS Foundation Trust, University College Hospital, 235 Euston Road, London NW1 2BU (United Kingdom); Guiney, Michael J. [Department of Imaging, University College London Hospitals NHS Foundation Trust, University College Hospital, 235 Euston Road, London NW1 2BU (United Kingdom); Brookes, Jocelyn A. [Department of Imaging, University College London Hospitals NHS Foundation Trust, University College Hospital, 235 Euston Road, London NW1 2BU (United Kingdom); Lees, William R. [Department of Imaging, University College London Hospitals NHS Foundation Trust, University College Hospital, 235 Euston Road, London NW1 2BU (United Kingdom)

    2006-08-15

    Purpose: Major arterial hemorrhage is an uncommon but serious complication of pancreatitis with high morbidity and mortality. Digital subtraction angiography (DSA) has long been the gold standard for the detection of a visceral artery pseudoaneurysm or for the site of active bleeding in patients with pancreatitis. Multi-section CT angiography is a minimally invasive technique which can provide high-resolution and high-contrast images of the arterial lumen and wall, with a much lower risk of complication and morbidity compared to DSA. The aim of this study was to determine the accuracy of multi-section CT angiography for the diagnosis of arterial complications of inflammatory pancreatitic disease. Materials and methods: A retrospective analysis of all patients undergoing visceral angiography for major bleeding as a complication of pancreatitis between 1998 and 2004 was performed. Twenty-nine studies in 25 patients (20 males, 5 females) with a mean age of 50.9 years (range 11-67 years) were identified where multi-section CT angiography was performed in the 24 h preceding the digital subtraction angiogram. Results: Digital subtraction angiography detected a pseudoaneurysm or contrast extravasation in 19 studies and no bleeding was demonstrated in 9 studies. CT angiography correctly identified the site and type of bleeding in 18 of the 19 positive studies. CT angiography detected extravasation of contrast in one study that was not demonstrated on digital subtraction angiography. The sensitivity and specificity for multi-section CT angiography for the detection of major arterial bleeding on a background of pancreatitis were 0.947 and 0.900, respectively. Conclusion: Multi-section CT angiography is a sensitive and accurate technique for the detection of major arterial hemorrhage in inflammatory pancreatic disease and should be considered as the first investigation in the management of these patients.

  18. Minimally Invasive Monitoring of Chronic Central Venous Catheter Patency in Mice Using Digital Subtraction Angiography (DSA.

    Directory of Open Access Journals (Sweden)

    Giovanna Figueiredo

    Full Text Available Repetitive administration of medication or contrast agents is frequently performed in mice. The introduction of vascular access mini-ports (VAMP for mice allows long-term vascular catheterization, hereby eliminating the need for repeated vessel puncture. With catheter occlusion being the most commonly reported complication of chronic jugular vein catheterization, we tested whether digital subtraction angiography (DSA can be utilized to evaluate VAMP patency in mice.Twenty-three mice underwent catheterization of the jugular vein and subcutaneous implantation of a VAMP. The VAMP was flushed every second day with 50 μL of heparinized saline solution (25 IU/ml. DSA was performed during injection of 100 μL of an iodine based contrast agent using an industrial X-ray inspection system intraoperatively, as well as 7±2 and 14±2 days post implantation.DSA allowed localization of catheter tip position, to rule out dislocation, kinking or occlusion of a microcatheter, and to evaluate parent vessel patency. In addition, we observed different ante- and retrograde collateral flow patterns in case of jugular vein occlusion. More exactly, 30% of animals showed parent vessel occlusion after 7±2 days in our setting. At this time point, nevertheless, all VAMPs verified intravascular contrast administration. After 14±2 days, intravascular contrast injection was verified in 70% of the implanted VAMPs, whereas at this point of time 5 animals had died or were sacrificed and in 2 mice parent vessel occlusion hampered intravascular contrast injection. Notably, no occlusion of the catheter itself was observed.From our observations we conclude DSA to be a fast and valuable minimally invasive tool for investigation of catheter and parent vessel patency and for anatomical studies of collateral blood flow in animals as small as mice.

  19. Vascular invasion of klatskin tumor : computed tomography vs digital subtraction angiography in determining resectability

    Energy Technology Data Exchange (ETDEWEB)

    Cha, Joo Hee; Han, Joon Koo; Kim, Tae Kyoung; Sin, Sang Jun; Hong, Hye Sook; Park, Jae Hyung; Choi, Byung Ihn; Kim, Sun Whe [College of Medicine, the Institute of Radiation Medicine, Seoul National University, Seoul (Korea, Republic of); Song, Chi Sung [Borame Hospital, Seoul (Korea, Republic of)

    2000-02-01

    To compare the accuracy of computed tomography (CT) with that of digital subtraction angiography (DSA) in predicting the resectability of Klatskin tumor on the basis of vascular invasion. Twenty-five patients with Klatskin tumor who had undergone laparotomy were included in this study. In order to assess the surgical resectability of their tumors, the preoperative CT scans and DSA of these patients were retrospectively assessed in terms of vascular invasion. The criteria of unresectability were tumoral invasion of the proper hepatic artery or main portal vein, or simultaneous invasion of the hepatic artery on one side and the other side portal vein. Tumors were unresectable in 13 cases, and resectable in 12. CT and DSA predicted nine and three tumors as unresectable ones, respectively. The sensitivity, specificity, positive predictive value, negative predictive value and accuracy of CT in determining whether a tumor was unresectable were 61.5%, 91.7%, 88.9%, 68.8% and 76.0%, respectively. For DSA, the respective figures were 23.1%, 100%, 100%, 54.5%, and 60%. For the detection of vascular invasion without diameter change, CT was superior to DSA; for the evaluation of vascular anatomy, it was, however, less effective. CT failed to detect small hepatic metastasis (n=3D2), lymph node metastasis (n=3D1), variation of the bile duct (n=3D1), and the distal extent of tumor in the bile duct (n=3D1), factors which precluded surgical resection. CT is a reliable method for the detection of vascular invasion and tumor unresectability. For the detection of vascular anatomic variation, the combined use of CT and DSA would be helpful. (author)

  20. Quantitative blood flow measurements in the small animal cardiopulmonary system using digital subtraction angiography

    Energy Technology Data Exchange (ETDEWEB)

    Lin Mingde; Marshall, Craig T.; Qi, Yi; Johnston, Samuel M.; Badea, Cristian T.; Piantadosi, Claude A.; Johnson, G. Allan [Department of Radiology, Center for In Vivo Microscopy and Department of Biomedical Engineering, Duke University Medical Center, Box 3302, Durham, North Carolina 27710 (United States); Division of Pulmonary and Critical Care Medicine and Center for Hyperbaric Medicine and Environmental Physiology, Duke University Medical Center, Box 3823, Durham, North Carolina 27710 (United States); Department of Radiology, Center for In Vivo Microscopy, Duke University Medical Center, Box 3302, Durham, North Carolina 27710 (United States); Department of Radiology, Center for In Vivo Microscopy and Department of Biomedical Engineering, Duke University Medical Center, Box 3302, Durham, North Carolina 27710 (United States); Department of Radiology, Center for In Vivo Microscopy, Duke University Medical Center, Box 3302, Durham, North Carolina 27710 (United States); Division of Pulmonary and Critical Care Medicine and Center for Hyperbaric Medicine and Environmental Physiology, Duke University Medical Center, Box 3823, Durham, North Carolina 27710 (United States); Department of Radiology, Center for In Vivo Microscopy and Department of Biomedical Engineering, Duke University Medical Center, Box 3302, Durham, North Carolina 27710 (United States)

    2009-11-15

    Purpose: The use of preclinical rodent models of disease continues to grow because these models help elucidate pathogenic mechanisms and provide robust test beds for drug development. Among the major anatomic and physiologic indicators of disease progression and genetic or drug modification of responses are measurements of blood vessel caliber and flow. Moreover, cardiopulmonary blood flow is a critical indicator of gas exchange. Current methods of measuring cardiopulmonary blood flow suffer from some or all of the following limitations--they produce relative values, are limited to global measurements, do not provide vasculature visualization, are not able to measure acute changes, are invasive, or require euthanasia. Methods: In this study, high-spatial and high-temporal resolution x-ray digital subtraction angiography (DSA) was used to obtain vasculature visualization, quantitative blood flow in absolute metrics (ml/min instead of arbitrary units or velocity), and relative blood volume dynamics from discrete regions of interest on a pixel-by-pixel basis (100x100 {mu}m{sup 2}). Results: A series of calibrations linked the DSA flow measurements to standard physiological measurement using thermodilution and Fick's method for cardiac output (CO), which in eight anesthetized Fischer-344 rats was found to be 37.0{+-}5.1 ml/min. Phantom experiments were conducted to calibrate the radiographic density to vessel thickness, allowing a link of DSA cardiac output measurements to cardiopulmonary blood flow measurements in discrete regions of interest. The scaling factor linking relative DSA cardiac output measurements to the Fick's absolute measurements was found to be 18.90xCO{sub DSA}=CO{sub Fick}. Conclusions: This calibrated DSA approach allows repeated simultaneous visualization of vasculature and measurement of blood flow dynamics on a regional level in the living rat.

  1. Classification-based summation of cerebral digital subtraction angiography series for image post-processing algorithms

    Energy Technology Data Exchange (ETDEWEB)

    Schuldhaus, D; Spiegel, M; Polyanskaya, M; Hornegger, J [Pattern Recognition Lab, University Erlangen-Nuremberg (Germany); Redel, T [Siemens AG Healthcare Sector, Forchheim (Germany); Struffert, T; Doerfler, A, E-mail: martin.spiegel@informatik.uni-erlangen.de [Department of Neuroradiology, University Erlangen-Nuremberg (Germany)

    2011-03-21

    X-ray-based 2D digital subtraction angiography (DSA) plays a major role in the diagnosis, treatment planning and assessment of cerebrovascular disease, i.e. aneurysms, arteriovenous malformations and intracranial stenosis. DSA information is increasingly used for secondary image post-processing such as vessel segmentation, registration and comparison to hemodynamic calculation using computational fluid dynamics. Depending on the amount of injected contrast agent and the duration of injection, these DSA series may not exhibit one single DSA image showing the entire vessel tree. The interesting information for these algorithms, however, is usually depicted within a few images. If these images would be combined into one image the complexity of segmentation or registration methods using DSA series would drastically decrease. In this paper, we propose a novel method automatically splitting a DSA series into three parts, i.e. mask, arterial and parenchymal phase, to provide one final image showing all important vessels with less noise and moving artifacts. This final image covers all arterial phase images, either by image summation or by taking the minimum intensities. The phase classification is done by a two-step approach. The mask/arterial phase border is determined by a Perceptron-based method trained from a set of DSA series. The arterial/parenchymal phase border is specified by a threshold-based method. The evaluation of the proposed method is two-sided: (1) comparison between automatic and medical expert-based phase selection and (2) the quality of the final image is measured by gradient magnitudes inside the vessels and signal-to-noise (SNR) outside. Experimental results show a match between expert and automatic phase separation of 93%/50% and an average SNR increase of up to 182% compared to summing up the entire series.

  2. Classification-based summation of cerebral digital subtraction angiography series for image post-processing algorithms

    Science.gov (United States)

    Schuldhaus, D.; Spiegel, M.; Redel, T.; Polyanskaya, M.; Struffert, T.; Hornegger, J.; Doerfler, A.

    2011-03-01

    X-ray-based 2D digital subtraction angiography (DSA) plays a major role in the diagnosis, treatment planning and assessment of cerebrovascular disease, i.e. aneurysms, arteriovenous malformations and intracranial stenosis. DSA information is increasingly used for secondary image post-processing such as vessel segmentation, registration and comparison to hemodynamic calculation using computational fluid dynamics. Depending on the amount of injected contrast agent and the duration of injection, these DSA series may not exhibit one single DSA image showing the entire vessel tree. The interesting information for these algorithms, however, is usually depicted within a few images. If these images would be combined into one image the complexity of segmentation or registration methods using DSA series would drastically decrease. In this paper, we propose a novel method automatically splitting a DSA series into three parts, i.e. mask, arterial and parenchymal phase, to provide one final image showing all important vessels with less noise and moving artifacts. This final image covers all arterial phase images, either by image summation or by taking the minimum intensities. The phase classification is done by a two-step approach. The mask/arterial phase border is determined by a Perceptron-based method trained from a set of DSA series. The arterial/parenchymal phase border is specified by a threshold-based method. The evaluation of the proposed method is two-sided: (1) comparison between automatic and medical expert-based phase selection and (2) the quality of the final image is measured by gradient magnitudes inside the vessels and signal-to-noise (SNR) outside. Experimental results show a match between expert and automatic phase separation of 93%/50% and an average SNR increase of up to 182% compared to summing up the entire series.

  3. A 2D driven 3D vessel segmentation algorithm for 3D digital subtraction angiography data

    Energy Technology Data Exchange (ETDEWEB)

    Spiegel, M; Hornegger, J [Pattern Recognition Lab, University Erlangen-Nuremberg, Erlangen (Germany); Redel, T [Siemens AG Healthcare Sector, Forchheim (Germany); Struffert, T; Doerfler, A, E-mail: martin.spiegel@informatik.uni-erlangen.de [Department of Neuroradiology, University Erlangen-Nuremberg, Erlangen (Germany)

    2011-10-07

    Cerebrovascular disease is among the leading causes of death in western industrial nations. 3D rotational angiography delivers indispensable information on vessel morphology and pathology. Physicians make use of this to analyze vessel geometry in detail, i.e. vessel diameters, location and size of aneurysms, to come up with a clinical decision. 3D segmentation is a crucial step in this pipeline. Although a lot of different methods are available nowadays, all of them lack a method to validate the results for the individual patient. Therefore, we propose a novel 2D digital subtraction angiography (DSA)-driven 3D vessel segmentation and validation framework. 2D DSA projections are clinically considered as gold standard when it comes to measurements of vessel diameter or the neck size of aneurysms. An ellipsoid vessel model is applied to deliver the initial 3D segmentation. To assess the accuracy of the 3D vessel segmentation, its forward projections are iteratively overlaid with the corresponding 2D DSA projections. Local vessel discrepancies are modeled by a global 2D/3D optimization function to adjust the 3D vessel segmentation toward the 2D vessel contours. Our framework has been evaluated on phantom data as well as on ten patient datasets. Three 2D DSA projections from varying viewing angles have been used for each dataset. The novel 2D driven 3D vessel segmentation approach shows superior results against state-of-the-art segmentations like region growing, i.e. an improvement of 7.2% points in precision and 5.8% points for the Dice coefficient. This method opens up future clinical applications requiring the greatest vessel accuracy, e.g. computational fluid dynamic modeling.

  4. Classification-based summation of cerebral digital subtraction angiography series for image post-processing algorithms.

    Science.gov (United States)

    Schuldhaus, D; Spiegel, M; Redel, T; Polyanskaya, M; Struffert, T; Hornegger, J; Doerfler, A

    2011-03-21

    X-ray-based 2D digital subtraction angiography (DSA) plays a major role in the diagnosis, treatment planning and assessment of cerebrovascular disease, i.e. aneurysms, arteriovenous malformations and intracranial stenosis. DSA information is increasingly used for secondary image post-processing such as vessel segmentation, registration and comparison to hemodynamic calculation using computational fluid dynamics. Depending on the amount of injected contrast agent and the duration of injection, these DSA series may not exhibit one single DSA image showing the entire vessel tree. The interesting information for these algorithms, however, is usually depicted within a few images. If these images would be combined into one image the complexity of segmentation or registration methods using DSA series would drastically decrease. In this paper, we propose a novel method automatically splitting a DSA series into three parts, i.e. mask, arterial and parenchymal phase, to provide one final image showing all important vessels with less noise and moving artifacts. This final image covers all arterial phase images, either by image summation or by taking the minimum intensities. The phase classification is done by a two-step approach. The mask/arterial phase border is determined by a Perceptron-based method trained from a set of DSA series. The arterial/parenchymal phase border is specified by a threshold-based method. The evaluation of the proposed method is two-sided: (1) comparison between automatic and medical expert-based phase selection and (2) the quality of the final image is measured by gradient magnitudes inside the vessels and signal-to-noise (SNR) outside. Experimental results show a match between expert and automatic phase separation of 93%/50% and an average SNR increase of up to 182% compared to summing up the entire series.

  5. CT angiographic analysis of carotid artery stenosis: comparison of manual assessment, semiautomatic vessel analysis, and digital subtraction angiography.

    Science.gov (United States)

    Silvennoinen, H M; Ikonen, S; Soinne, L; Railo, M; Valanne, L

    2007-01-01

    To compare multisection CT angiography (CTA) analyzed with source/maximum intensity projection (MIP) images as well as semiautomated vessel analysis software with intra-arterial digital subtraction angiography (DSA) in detection and grading of carotid artery bifurcation stenosis. Consecutive patients with sonography evidence of a marked internal carotid artery stenosis underwent both carotid CTA and DSA (37 patients, 73 vessels). In CTA, the grade of stenosis was determined using axial source and MIP images as well as vessel analysis. The scans were blind-analyzed by 2 neuroradiologists using the NASCET criteria. Correlation of CTA source/MIP images versus DSA estimates of stenosis (R = 0.95) was higher than for the vessel analysis method versus DSA (R = 0.89). Compared with DSA, CTA source/MIP images underestimated high (78.2% versus 86.4%, P grades of stenosis (57.3% versus 63.1%, P grade stenosis, sensitivity and specificity of source/MIP image CTA were 75% and 96%, respectively, whereas for the vessel analysis method, they were 47% and 96%, respectively. For moderate stenosis, the source/MIP image CTA sensitivity and specificity were 88% and 82%, respectively, and for vessel analysis method, 62% and 82%, respectively. CTA detected all 4 occlusions. In evaluation of carotid stenosis, CTA provides an adequate, less invasive alternative with a high correlation to conventional DSA, though it tends to underestimate clinically relevant grades of stenosis. Its accuracy is not improved by semiautomated analysis. The data support the use of CTA in confirming carotid occlusion.

  6. Blood Pool Contrast-enhanced Magnetic Resonance Angiography with Correlation to Digital Subtraction Angiography: A Pictorial Review

    Directory of Open Access Journals (Sweden)

    Martha-Grace Knuttinen

    2014-01-01

    Full Text Available Magnetic resonance angiography (MRA provides noninvasive visualization of the vascular supply of soft tissue masses and vascular pathology, without harmful radiation. This is important for planning an endovascular intervention, and helps to evaluate the efficiency and effectiveness of the treatment. MRA with conventional extracellular contrast agents relies on accurate contrast bolus timing, limiting the imaging window to first-pass arterial phase. The recently introduced blood pool contrast agent (BPCA, gadofosveset trisodium, reversibly binds to human serum albumin, resulting in increased T1 relaxivity and prolonged intravascular retention time, permitting both first-pass and steady-state phase high-resolution imaging. In our practice, high-quality MRA serves as a detailed "roadmap" for the needed endovascular intervention. Cases of aortoiliac occlusive disease, inferior vena cava thrombus, pelvic congestion syndrome, and lower extremity arteriovenous malformation are discussed in this article. MRA was acquired at 1.5 T with an 8-channel phased array coil after intravenous administration of gadofosveset (0.03 mmol/kg body weight, at the first-pass phase. In the steady-state, serial T1-weighted 3D spoiled gradient echo images were obtained with high resolution. All patients underwent digital subtraction angiography (DSA and endovascular treatment. MRA and DSA findings of vascular anatomy and pathology are discussed and correlated. BPCA-enhanced MRA provides high-quality first-pass and steady-state vascular imaging. This could increase the diagnostic accuracy and create a detailed map for pre-intervention planning. Understanding the pharmacokinetics of BPCA and being familiar with the indications and technique of MRA are important for diagnosis and endovascular intervention.

  7. Estimating breast thickness for dual-energy subtraction in contrast-enhanced digital mammography using calibration phantoms

    Science.gov (United States)

    Lau, Kristen C.; Kwon, Young Joon; Aziz, Moez Karim; Acciavatti, Raymond J.; Maidment, Andrew D. A.

    2016-04-01

    Dual-energy contrast-enhanced digital mammography (DE CE-DM) uses an iodinated contrast agent to image the perfusion and vasculature of the breast. DE images are obtained by a weighted logarithmic subtraction of the high-energy (HE) and low-energy (LE) image pairs. We hypothesized that the optimal DE subtraction weighting factor is thickness-dependent, and developed a method for determining breast tissue composition and thickness in DE CE-DM. Phantoms were constructed using uniform blocks of 100% glandular-equivalent and 100% adipose-equivalent material. The thickness of the phantoms ranged from 3 to 8 cm, in 1 cm increments. For a given thickness, the glandular-adipose composition of the phantom was varied using different combinations of blocks. The logarithmic LE and logarithmic HE signal intensities were measured; they decrease linearly with increasing glandularity for a given thickness. The signals decrease with increasing phantom thickness and the x-ray signal decreases linearly with thickness for a given glandularity. As the thickness increases, the attenuation difference per additional glandular block decreases, indicating beam hardening. From the calibration mapping, we have demonstrated that we can predict percent glandular tissue and thickness when given two distinct signal intensities. Our results facilitate the subtraction of tissue at the boundaries of the breast, and aid in discriminating between contrast agent uptake in glandular tissue and subtraction artifacts.

  8. Digital subtraction radiographic analysis of the combination of bioabsorbable membrane and bovine morphogenetic protein pool in human periodontal infrabony defects

    Directory of Open Access Journals (Sweden)

    Maria do Carmo Machado Guimarães

    2010-08-01

    Full Text Available OBJECTIVES: This study assessed the bone density gain and its relationship with the periodontal clinical parameters in a case series of a regenerative therapy procedure. MATERIAL AND METHODS: Using a split-mouth study design, 10 pairs of infrabony defects from 15 patients were treated with a pool of bovine bone morphogenetic proteins associated with collagen membrane (test sites or collagen membrane only (control sites. The periodontal healing was clinically and radiographically monitored for six months. Standardized pre-surgical and 6-month postoperative radiographs were digitized for digital subtraction analysis, which showed relative bone density gain in both groups of 0.034 ± 0.423 and 0.105 ± 0.423 in the test and control group, respectively (p>0.05. RESULTS: As regards the area size of bone density change, the influence of the therapy was detected in 2.5 mm² in the test group and 2 mm² in the control group (p>0.05. Additionally, no correlation was observed between the favorable clinical results and the bone density gain measured by digital subtraction radiography (p>0.05. CONCLUSIONS: The findings of this study suggest that the clinical benefit of the regenerative therapy observed did not come with significant bone density gains. Long-term evaluation may lead to a different conclusions.

  9. Multimodality evaluation of dural arteriovenous fistula with CT angiography, MR with arterial spin labeling, and digital subtraction angiography: case report.

    Science.gov (United States)

    Alexander, Matthew; McTaggart, Ryan; Santarelli, Justin; Fischbein, Nancy; Marks, Michael; Zaharchuk, Greg; Do, Huy

    2014-01-01

    Dural arteriovenous fistulae (DAVF) are cerebrovascular lesions with pathologic shunting into the venous system from arterial feeders. Digital subtraction angiography (DSA) has long been considered the gold standard for diagnosis, but advances in noninvasive imaging techniques now play a role in the diagnosis of these complex lesions. Herein, we describe the case of a patient with right-side pulsatile tinnitus and DAVF diagnosed using computed tomography angiography, magnetic resonance with arterial spin labeling, and DSA. Implications for imaging analysis of DAVFs and further research are discussed.

  10. [X-ray semiotics of sialolithiasis in functional digital subtraction sialography].

    Science.gov (United States)

    Iudin, L A; Kondrashin, S A; Afanas'ev, V V; Shchipskiĭ, A V

    1995-01-01

    Twenty-seven patients with sialolithiasis were examined using functional subtraction sialography developed by the authors. Differential diagnostic signs characterizing the degree of involvement of the salivary gland were defined. High efficacy of the method helps correctly plan the treatment strategy.

  11. Comparison Of Digital Workstations And Conventional Reading For Evaluation Of User Interfaces In Digital Radiology

    Science.gov (United States)

    McNeill, Kevin M.; Seeley, George W.; Maloney, Kris; Fajardo, Laurie; Kozik, Mark

    1988-06-01

    The User Interface Study Group at the University of Arizona is investigating the interaction of Radiologists with digital workstations. Using the Arizona Viewing Console we have conducted an experiment to compare a digital workstation with a particular conventional reading process used for cases from a local Health Maintenance Organization. A model consisting of three distinct phases of activity was developed to describe conventional reading process. From this model software was developed for the Arizona Viewing Console to approximate the process. Radiologists were then video taped reading similar sets of cases at each workstation and the tapes were analyzed for frequency of hand movements and time required for each phase of the process. This study provides a comparison between conventional reading and a digital workstation. This paper describes the reading process, the model and its approximation on the digital workstation, as well as the analysis of the video tapes.

  12. Comparison of conventional and digital cephalometric analysis: A pilot study

    Directory of Open Access Journals (Sweden)

    Hemlata Bhagwan Tanwani

    2014-01-01

    Full Text Available Aim: The aim of the study was to analyze and compare the manual cephalometric tracings with computerized cephalometric tracings using Burstone hard tissue analysis and McNamara analysis. Materials and Methods: Conventional lateral cephalograms of 20 subjects were obtained and manually traced. The radiographs were subsequently scanned and digitized using Dolphin Imaging software version 11.7. McNamara analysis and Burstone hard tissue analysis were performed by both conventional and digital method. No differentiations were made for age or gender. Data were subjected to statistical analysis. Statistical analysis was undertaken using SPSS 17.0 version (Chicago, Illinois, USA statistical software program. A paired t-test was used to detect differences between the manual and digital methods. Statistical significance was set at the P < 0.05 level of confidence. Results: (A From Burstone analysis variables N-Pg II Hp show statistically very significant difference, and ANS-N, U1-NF, N-B II Hp, L1-Mp, and Go-Pg shows the statistically significant difference. (B From McNamara analysis variables Nasolabial angle and L1-APog show statistically significant differences and the Mandibular length shows the statistically very significant difference. Conclusion: According to this study, is reasonable to conclude that the manual and digital tracings show the statistically significant difference.

  13. Clinical value of three-dimensional digital subtraction angiography in the endovascular treatment of intracranial aneurysms

    Institute of Scientific and Technical Information of China (English)

    Tianxiao Li; Dengwei Zong

    2006-01-01

    BACKGROUND: The endovascular treatment of intracranial aneurysms requires clearly displayed anatomic structures of the aneurysm and the reference image of the aneurysm neck, the images of the form and struc ture of the aneurysm and the three-dimensional (3D) intracranial vascular structure are very important for the diagnosis and treatment of cerebral aneurysms. OBJECTIVE: To investigate the value of 3D digital subtraction angiography (3D DSA) in diagnosing intracra nial aneurysm, and compare the reliability with two-dimensional (2D) DSA in evaluating the intracranial aneurysm suitable for the endovascular occlusion: DESIGN: A double-blind case observation. SETTING: Department of Interventional Radiology, Henan People's Hospital. PARTICIPANTS: The patients, who were suspected to have intracranial aneurysms, were examined with 2D DSA and 3D DSA in Henan People's Hospital from October 2004 to October 2005. Fifty intracranial aneurysms were detected in 44 patients (19 males and 25 females) of 30-75 years, with an average of 51 years, including 5 cases were multiple aneurysms, including 2 aneurysms in 4 cases and 3 aneurysms in 1 case. The aneurysms located respectively at internal carotid artery (n =19), anterior cerebral artery (n =16), middle cerebral artery (n =8), basilar artery (n =6), and posterior inferior cerebellar artery (n =1 ). METHODS: The 50 ruptured intracranial aneurysms were examined with 2D DSA and 3D DSA. The method of volume reconstruction was applied to reconstruct the 3D DSA images, and the automatically generated images could be shifted, rotated and magnified, besides, the corresponding processing could also be performed, including resecting the unnecessary structure and sharpening margin of the images. Observations: ① Display of aneurysm neck: The site and range of the aneurysm neck, and the involvement of branches originated from the aneurysm arteries; ② Display of aneurysm form: The displays of aneurysm form and with or without arteries

  14. The comparative effectiveness of conventional and digital image libraries.

    Science.gov (United States)

    McColl, R I; Johnson, A

    2001-03-01

    Before introducing a hospital-wide image database to improve access, navigation and retrieval speed, a comparative study between a conventional slide library and a matching image database was undertaken to assess its relative benefits. Paired time trials and personal questionnaires revealed faster retrieval rates, higher image quality, and easier viewing for the pilot digital image database. Analysis of confidentiality, copyright and data protection exposed similar issues for both systems, thus concluding that the digital image database is a more effective library system. The authors suggest that in the future, medical images will be stored on large, professionally administered, centrally located file servers, allowing specialist image libraries to be tailored locally for individual users. The further integration of the database with web technology will enable cheap and efficient remote access for a wide range of users.

  15. Three-dimensional volume rendering digital subtraction angiography in comparison with two-dimensional digital subtraction angiography and rotational angiography for detecting aneurysms and their morphological properties in patients with subarachnoid hemorrhage

    Energy Technology Data Exchange (ETDEWEB)

    Kucukay, Fahrettin, E-mail: fkucukay@hotmail.com [Turkiye Yuksek Ihtisas Hospital, Department of Radiology, Ankara (Turkey); Okten, R. Sarper [Turkiye Yuksek Ihtisas Hospital, Department of Radiology, Ankara (Turkey); Tekiner, Ayhan [Ankara Education and Teaching Hospital, Department of Neurosurgery, Ankara (Turkey); Dagli, Mustafa [Turkiye Yuksek Ihtisas Hospital, Department of Radiology, Ankara (Turkey); Gocek, Cevdet; Bayar, Mehmet Akif [Ankara Education and Teaching Hospital, Department of Neurosurgery, Ankara (Turkey); Cumhur, Turhan [Turkiye Yuksek Ihtisas Hospital, Department of Radiology, Ankara (Turkey)

    2012-10-15

    Objective: Subarachnoid hemorrhage (SAH), which can cause mortality and severe morbidity, is a serious condition whose underlying cause must be determined. We aimed to compare 2D digital subtraction angiography (2DDSA), rotational angiography (RA) and 3D volume rendering digital subtraction angiography (3DVRDSA) for detecting aneurysms and their morphological properties in patients with subarachnoid hemorrhage. Materials and methods: After an initial diagnosis of SAH with computed tomography, 122 patients (52 males and 70 females with a mean age of 47.77 ± 12.81 ranging between 20 and 83 years) underwent 2DDSA imaging, RA and 3DVRDSA imaging for detection of aneurysms. The location of the aneurysm, the best working angles, the dome/neck ratios, the largest diameter of the aneurysm, the shape of the aneurysm, the presence of spasms or pseudostenoses, and the relationship to the neighboring arteries were recorded. Results: 2DDSA missed 15.6% of the aneurysms that had a mean size of 2.79 ± 0.74 mm. RA was superior to 2DDSA for detecting aneurysm neck, and 3DVRDSA was superior to RA for detecting aneurysm neck. 3DVRDSA conclusively depicted the shape of the aneurysms in all patients. 3DVRDSA imaging was superior to 2DDSA and RA in the detection of the aneurysm relationship to neighboring arteries. The sensitivity and specificity of 3DVRDSA imaging for the detection of vasospasms were 100 and 84%, respectively. Conclusions: 3DVRDSA imaging is superior to 2DDSA and RA for detecting intracranial aneurysms and their morphological properties, especially those of small, ruptured aneurysms. However, 2DDSA should not be neglected in cases of vasospasm.

  16. Evaluation of the lower limb vasculature before free fibula flap transfer. A prospective blinded comparison between magnetic resonance angiography and digital subtraction angiography

    NARCIS (Netherlands)

    Klein, Steven; Van Lienden, Krijn P; Van't Veer, Marcel; Smit, Jeroen M; Werker, Paul M N

    2013-01-01

    Introduction The aim of this study was to compare magnetic resonance angiography (MRA) with digital subtraction angiography (DSA) in the preoperative assessment of crural arteries and their skin perforators prior to free fibular transfer. Patients and methods Fifteen consecutive patients, scheduled

  17. Suppression of high-density artifacts in x-ray CT images using temporal digital subtraction with application to cryotherapy

    Science.gov (United States)

    Baissalov, Roustem; Sandison, George A.; Donnelly, Bryan J.; Saliken, John C.; Muldrew, Ken; Rewcastle, John C.

    2000-06-01

    Image guidance of cryotherapy is usually performed using ultrasound or x-ray CT. Despite the ability of CT to display the full 3D structure of the iceball, including frozen and unfrozen regions, the quality of the images is compromised by the presence of high density streak artifacts. To suppress these artifacts we applied Temporal Digital Subtraction (TDS). This TDS method has the added advantage of improving the gray scale contrast between frozen and unfrozen tissue in the CT images. Two sets of CT images were taken of a phantom material, cryoprobes and a urethral warmer (UW) before and during the cryoprobe freeze cycle. The high density artifacts persisted in both image sets. TDS was performed on these two image sets using the corresponding mask image of unfrozen material and the same geometrical configuration of the cryoprobes and the UW. The resultant difference image had a significantly reduced content of the artifacts. This TDS can be used in x-ray CT assisted cryotherapy to significantly suppress or eliminate high density x-ray CT streak artifacts by digitally processing x-ray CT images. Applying TDS in cryotherapy will facilitate estimation of the amount and location of all frozen and unfrozen regions, potentially making cryotherapy safer and less operator dependent.

  18. A quantitative study of bone repair after endodontic therapy on digital subtraction radiography

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jae Duk [Dept. of Oral and Maxillofacial Radiology, College of Dentistry, Chosun University, Kwangju (Korea, Republic of)

    1997-08-15

    This study was performed to prepare the quantitative method of judging the sensitive prognosis of chronic apical periodontitis as early as possible. The subjects were 25 cases with periapical radiolucencies of which were treated with endodontic treatment. Serial radiographs were taken by standardized method longitudinally. The density slice function of digital radiographic system were employed for quantitative and longitudinal assessment of the radiolucent area and the condensing osteitis simultaneously. Obtained results were as follows: 1. The amount of bone repair after endodontic treatment could be detected quantitatively by the density slice function of digital radiographic system. 2. Within the 6-week period after root canal filling, the prognosis could be evaluated by assessment both radiolucent area and condensing osteitis on digital radiographic system. 3. The pattern of bone repair showed peripheral type in most cases from the 6th week after root canal filling. 4. In longitudinal change, bone repair showed two patterns; the succeeding reduction of radiolucent area showing the increase of condensing osteitis in size till 6th week and following by static state or reduction tendency and the reduction following the initial increase of both areas. 5. Cases with pulpitis by trauma showed initial increase of condensing osteitis at 2nd week, marked reduction of radiolucent area and condensing osteitis at 6th week, and approximately normal bone state at 8th week after root canal filling.

  19. Evaluation of the pedal artery: comparison of three-dimensional gadolinium-enhanced MR angiography with digital subtraction angiography

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jeong Min; Kang, Sung Gwon; Byun, Joo Nam; Kim, Young Cheol; Choi, Jeong Yeol; Kim, Dong Hyun [College of Medicine, Chosun Univ., Kwangju (Korea, Republic of)

    2002-07-01

    To compare the three-dimensional gadolinium-enhanced MR angiography with digital subtraction angiography (DSA) for evaluation of the pedal artery. In 12 extremities of 11 patients, both digital subtraction angiography (DSA) and contrast-enhanced MR angiography (CE-MR angiography) were performed during the same week. Among ten of the 11 patients, the following conditions were present: atherosclerosis (n=4), diabetic foot (n=3), Buerger's disease (n=1), calciphylactic arteriopathy (n=1) and arteriovenous malformation of the foot (n=1). The remaining patient underwent angiography prior to flap surgery. For MR angiography, a 1.5T system using an extremity or head coil was used. A three-dimensional FISP (fast imaging with steady state precession) sequence was obtained before enhancement, followed by four sequential acquisitions (scan time, 20 secs, scan interval time, 10 secs) 10 seconds after intravenous bolus injection of normal saline (total 10 cc), following intravenous administration of gadolinium (0.02 mmol/kg, 3 ml/sec). Arterial segments of the ankle and foot were classified as the anterior or posterior tibial artery, the distal peroneal artery, the medial or lateral plantar artery, the pedal arch, and the dorsalis pedis artery. Two radiologists independently analysed visualization of each arteraial segment and the mean of visible arterial segments in one extreminty using CE-MR angiography and DSA. Among 84 arterial segments, 16 were invisible at both CE-MR angiography and DSA, while 39 were demonstrated by both modalities. Twenty-six segments were visible only at CE-MR angiography and three only at DSA. CE-MR angiography displayed a higher number of arterial segments than DSA (mean, 5.42 vs. mean 3.50, respectively), a difference which was statistically significant (p<0.000). The difference between each arterial segment was not statistically significant, except for the dorsalis pedis artery (t test, p<0.000). In that it provides additional information for

  20. Subtractive Leadership

    Science.gov (United States)

    Larwin, K. H.; Thomas, Eugene M.; Larwin, David A.

    2015-01-01

    This paper introduces a new term and concept to the leadership discourse: Subtractive Leadership. As an extension of the distributive leadership model, the notion of subtractive leadership refers to a leadership style that detracts from organizational culture and productivity. Subtractive leadership fails to embrace and balance the characteristics…

  1. Use of cone-beam tomography and digital subtraction radiography for diagnosis and evaluation of traumatized teeth treated with endodontic surgery and MTA. A case report.

    Science.gov (United States)

    de Carvalho, Fabíola Bastos; Gonçalves, Paloma Souza; Lima, Regina Karla de Pontes; Guerreiro-Tanomaru, Juliane Maria; Rasquin, Luis Cardoso; Tanomaru-Filho, Mário

    2013-10-01

    The aim of this paper was to report the diagnosis and evaluation of periradicular bone repair by using computed tomography and digital subtraction radiography in an endodontic surgery case treated with mineral trioxide aggregate (MTA). The patient had local swelling and fistula 7 years after trauma in the upper jaw. Periapical lesion on tooth #12 and root resorption of tooth #11 were detected radiographically. Endodontic therapy and placement of intracanal medication were carried out. After 3 months, with no improvement in the clinical signs and symptoms, computed tomography was performed, showing extensive apical bone resorption on tooth #12 and dental resorption promoting communication of the root canal with the periodontium of tooth #11. The patient was referred to endodontic surgery. After surgery and postoperative periods of 15, 30, 60, 90, and 120 days, standardized radiographs were taken, digitized, and subjected to digital subtraction of the images using Adobe Photoshop CS software. Four years later, a cone-beam computed tomography was performed, showing bone repair and absence of root resorption at tooth #11. In this clinical case, digital subtraction radiography was effective for early detection of new bone formation and evolution of repair. © 2011 John Wiley & Sons A/S.

  2. Cerebral Circulation Time is Prolonged and Not Correlated with EDSS in Multiple Sclerosis Patients: A Study Using Digital Subtracted Angiography

    Science.gov (United States)

    Monti, Lucia; Donati, Donatella; Menci, Elisabetta; Cioni, Samuele; Bellini, Matteo; Grazzini, Irene; Leonini, Sara; Galluzzi, Paolo; Severi, Sauro; Burroni, Luca; Casasco, Alfredo; Morbidelli, Lucia; Santarnecchi, Emiliano; Piu, Pietro

    2015-01-01

    Literature has suggested that changes in brain flow circulation occur in patients with multiple sclerosis. In this study, digital subtraction angiography (DSA) was used to measure the absolute CCT value in MS patients and to correlate its value to age at disease onset and duration, and to expand disability status scale (EDSS). DSA assessment was performed on eighty MS patients and on a control group of forty-four age-matched patients. CCT in MS and control groups was calculated by analyzing the angiographic images. Lesion and brain volumes were calculated in a representative group of MS patients. Statistical correlations among CCT and disease duration, age at disease onset, lesion load, brain volumes and EDSS were considered. A significant difference between CCT in MS patients (mean = 4.9s; sd = 1.27s) and control group (mean = 2.8s; sd = 0.51s) was demonstrated. No significant statistical correlation was found between CCT and the other parameters in all MS patients. Significantly increased CCT value in MS patients suggests the presence of microvascular dysfunctions, which do not depend on clinical and MRI findings. Hemodynamic changes may not be exclusively the result of a late chronic inflammatory process. PMID:25679526

  3. Cerebral circulation time is prolonged and not correlated with EDSS in multiple sclerosis patients: a study using digital subtracted angiography.

    Directory of Open Access Journals (Sweden)

    Lucia Monti

    Full Text Available Literature has suggested that changes in brain flow circulation occur in patients with multiple sclerosis. In this study, digital subtraction angiography (DSA was used to measure the absolute CCT value in MS patients and to correlate its value to age at disease onset and duration, and to expand disability status scale (EDSS. DSA assessment was performed on eighty MS patients and on a control group of forty-four age-matched patients. CCT in MS and control groups was calculated by analyzing the angiographic images. Lesion and brain volumes were calculated in a representative group of MS patients. Statistical correlations among CCT and disease duration, age at disease onset, lesion load, brain volumes and EDSS were considered. A significant difference between CCT in MS patients (mean = 4.9s; sd = 1.27 s and control group (mean = 2.8s; sd = 0.51 s was demonstrated. No significant statistical correlation was found between CCT and the other parameters in all MS patients. Significantly increased CCT value in MS patients suggests the presence of microvascular dysfunctions, which do not depend on clinical and MRI findings. Hemodynamic changes may not be exclusively the result of a late chronic inflammatory process.

  4. Suppression of high-density artefacts in x-ray CT images using temporal digital subtraction with application to cryotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Baissalov, R.; Sandison, G.A.; Rewcastle, J.C. [Department of Medical Physics, Tom Baker Cancer Center, Calgary, Canada, T2N 4N2 2 Department of Physics and Astronomy, University of Calgary, Calgary T2N 2N4 (Canada); Donnelly, B.J. [Department of Surgery, Tom Baker Cancer Center, Calgary, Canada, T2N 4N2 4 Department of Surgery, Foothills Hospital, Calgary T2N 2T7 (Canada); Saliken, J.C. [Department of Surgery, Tom Baker Cancer Center, Calgary T2N 4N2 (Canada); Department of Diagnostic Imaging, Foothills Hospital, Calgary T2N 2T7 (Canada); McKinnon, J.G. [Department of Surgery, Foothills Hospital, Calgary T2N 2T7 (Canada); Muldrew, K. [Department of Surgery, Faculty of Medicine, University of Calgary, Calgary T2N 2T7 (Canada)

    2000-05-01

    Image guidance in cryotherapy is usually performed using ultrasound. Although not currently in routine clinical use, x-ray CT imaging is an alternative means of guidance that can display the full 3D structure of the iceball, including frozen and unfrozen regions. However, the quality of x-ray CT images is compromised by the presence of high-density streak artefacts. To suppress these artefacts we applied temporal digital subtraction (TDS). This TDS method has the added advantage of improving the grey-scale contrast between frozen and unfrozen tissue in the CT images. Two sets of CT images were taken of a phantom material, cryoprobes and a urethral warmer (UW) before and during the cryoprobe freeze cycle. The high-density artefacts persisted in both image sets. TDS was performed on these two image sets using the corresponding mask image of unfrozen material and the same geometrical configuration of the cryoprobes and the UW. The resultant difference image had a significantly reduced artefact content. Thus TDS can be used to significantly suppress or eliminate high-density CT streak artefacts without reducing the metallic content of the cryoprobes. In vivo study needs to be conducted to establish the utility of this TDS procedure for CT assisted prostate or liver cryotherapy. Applying TDS in x-ray CT guided cryotherapy will facilitate estimation of the number and location of all frozen and unfrozen regions, potentially making cryotherapy safer and less operator dependent. (author)

  5. Evaluation of changes of intracranial blood flow after carotid artery stenting using digital subtraction angiography flow assessment

    Institute of Scientific and Technical Information of China (English)

    Hajime; Wada; Masato; Saito; Kyousuke; Kamada

    2015-01-01

    AIM: To evaluate the changes of intracranial blood flow after carotid artery stenting(CAS), using the flow assessment application "Flow-Insight", which was developed in our department.METHODS: Twenty patients treated by CAS participated in this study. We analyzed the change in concentration of the contrast media at the anterior-posterior and profile view image with the flow assessment application "Flow-Insight". And we compared the results with N-isopropyl-p-[123I] iodoamphetamine-single-photon emission computed tomography(IMP SPECT) performed before and after the treatment. RESULTS: From this study, 200% of the parameter "blood flow" change in the post/pre-treatment is suggested as the critical line of the hyperperfusion syndrome arise. Although the observed blood flow increase in the digital subtraction angiography system did not strongly correlate with the rate of increase of SPECT, the "Flow-Insight" reflected the rate of change of the vessels well. However, for patients with reduced reserve blood flow before CAS, a highly elevated site was in agreement with the site analysis results. CONCLUSION: We concluded that the cerebral angiography flow assessment application was able to more finely reveal hyperperfusion regions in the brain after CAS compared to SPECT.

  6. Double-blind comparison of safety and efficacy of iomeprol and iopamidol in carotid digital subtraction angiography.

    Science.gov (United States)

    Beltramello, A; Piovan, E; Rosta, L

    1994-05-01

    Iomeprol is a nonionic monomer which provides injectable formulations with the lowest osmolalities and the lowest viscosities among the currently available low-osmolar radiographic contrast agents of the same category. These favourable physico-chemical characteristics, together with high water solubility and low molecular toxicity, make this agent particularly suitable for carotid angiography, a procedure in which contrast-induced blood-brain barrier damage is maximal. This single-centre, randomised, double-blind, parallel-group study aimed at comparing the safety, tolerance and efficacy of 200 mgI/ml solutions of iomeprol and iopamidol in 100 consenting adult inpatients undergoing carotid intra-arterial digital subtraction angiography (IA-DSA). Both agents appeared to be safe and well tolerated. Only minor and transient adverse events occurred throughout the study. Electroencephalographic and neurological examinations performed pre- and post-contrast showed no abnormality induced by the test compounds. Vessel opacification was good or excellent in the vast majority of technically adequate examinations. Information provided by the angiographic examination was useful for subsequent patient management in almost all cases. It is concluded that iomeprol-200 and iopamidol-200 are safe and effective contrast media when used for carotid IA-DSA, an examination which proves useful not only for the diagnosis of vascular lesions, but also to best direct the management of patients scheduled for surgery of intracranial tumors.

  7. Cerebral circulation time is prolonged and not correlated with EDSS in multiple sclerosis patients: a study using digital subtracted angiography.

    Science.gov (United States)

    Monti, Lucia; Donati, Donatella; Menci, Elisabetta; Cioni, Samuele; Bellini, Matteo; Grazzini, Irene; Leonini, Sara; Galluzzi, Paolo; Bracco, Sandra; Severi, Sauro; Burroni, Luca; Casasco, Alfredo; Morbidelli, Lucia; Santarnecchi, Emiliano; Piu, Pietro

    2015-01-01

    Literature has suggested that changes in brain flow circulation occur in patients with multiple sclerosis. In this study, digital subtraction angiography (DSA) was used to measure the absolute CCT value in MS patients and to correlate its value to age at disease onset and duration, and to expand disability status scale (EDSS). DSA assessment was performed on eighty MS patients and on a control group of forty-four age-matched patients. CCT in MS and control groups was calculated by analyzing the angiographic images. Lesion and brain volumes were calculated in a representative group of MS patients. Statistical correlations among CCT and disease duration, age at disease onset, lesion load, brain volumes and EDSS were considered. A significant difference between CCT in MS patients (mean = 4.9s; sd = 1.27 s) and control group (mean = 2.8s; sd = 0.51 s) was demonstrated. No significant statistical correlation was found between CCT and the other parameters in all MS patients. Significantly increased CCT value in MS patients suggests the presence of microvascular dysfunctions, which do not depend on clinical and MRI findings. Hemodynamic changes may not be exclusively the result of a late chronic inflammatory process.

  8. Whole-brain CT digital subtraction angiography of cerebral dural arteriovenous fistula using 320-detector row CT

    Energy Technology Data Exchange (ETDEWEB)

    Fujiwara, Hirokazu; Momoshima, Suketaka; Kuribayashi, Sachio [Keio University, Department of Diagnostic Radiology, School of Medicine, Tokyo (Japan); Akiyama, Takenori [Keio University, Department of Neurosurgery, School of Medicine, Tokyo (Japan)

    2013-07-15

    The purpose of this study was to evaluate the usefulness of CT digital subtraction angiography (CTDSA) by using 320-detector row CT in the diagnosis and classification of cerebral dural arteriovenous fistula (dAVF) and comparing it with DSA as the standard reference. A total of 29 CTDSA/DSA from 25 patients with dAVF were retrospectively evaluated by two neuroradiologists. The presence, Cognard classification, and feeding arteries of dAVFs on CTDSA were assessed according to DSA. DSA depicted 33 dAVFs in 28 cases. By consensus reading, CTDSA correctly detected 32 dAVFs in 27 cases and properly graded 31 lesions. The intermodality agreement for the presence and classification of dAVFs was excellent (kappa = 0.955 and 0.921, respectively). CTDSA detected 77 of 109 feeding arteries (70.6 %) in 25 cases. The intermodality agreement for the feeding arteries was good (kappa = 0.713). Although CTDSA is limited in temporal and spatial resolution in comparison with DSA, it is an effective non-invasive tool for the detection and classification of dAVF. (orig.)

  9. Initial testing of a 3D printed perfusion phantom using digital subtraction angiography

    Science.gov (United States)

    Wood, Rachel P.; Khobragade, Parag; Ying, Leslie; Snyder, Kenneth; Wack, David; Bednarek, Daniel R.; Rudin, Stephen; Ionita, Ciprian N.

    2015-03-01

    Perfusion imaging is the most applied modality for the assessment of acute stroke. Parameters such as Cerebral Blood Flow (CBF), Cerebral Blood volume (CBV) and Mean Transit Time (MTT) are used to distinguish the tissue infarct core and ischemic penumbra. Due to lack of standardization these parameters vary significantly between vendors and software even when provided with the same data set. There is a critical need to standardize the systems and make them more reliable. We have designed a uniform phantom to test and verify the perfusion systems. We implemented a flow loop with different flow rates (250, 300, 350 ml/min) and injected the same amount of contrast. The images of the phantom were acquired using a Digital Angiographic system. Since this phantom is uniform, projection images obtained using DSA is sufficient for initial validation. To validate the phantom we measured the contrast concentration at three regions of interest (arterial input, venous output, perfused area) and derived time density curves (TDC). We then calculated the maximum slope, area under the TDCs and flow. The maximum slope calculations were linearly increasing with increase in flow rate, the area under the curve decreases with increase in flow rate. There was 25% error between the calculated flow and measured flow. The derived TDCs were clinically relevant and the calculated flow, maximum slope and areas under the curve were sensitive to the measured flow. We have created a systematic way to calibrate existing perfusion systems and assess their reliability.

  10. Marginal Accuracy and Internal Fit of Dental Copings Fabricated by Modern Additive and Subtractive Digital Technologies.

    Science.gov (United States)

    Nelson, Neha; K S, Jyothi; Sunny, Kiran

    2017-03-01

    The margins of copings for crowns and retainers of fixed partial dentures affect the progress of microleakage and dental caries. Failures occur due to altered fit which is also influenced by the method of fabrication. An in-vitro study was conducted to determine among the cast base metal, copy milled zirconia, computer aided designing computer aided machining/manufacturing zirconia and direct metal laser sintered copings which showed best marginal accuracy and internal fit. Forty extracted maxillary premolars were mounted on an acrylic model and reduced occlusally using a milling machine up to a final tooth height of 4 mm from the cementoenamel junction. Axial reduction was accomplished on a surveyor and a chamfer finish line was given. The impressions and dies were made for fabrication of copings which were luted on the prepared teeth under standardized loading, embedded in self-cure acrylic resin, sectioned and observed using scanning electron microscope for internal gap and marginal accuracy. The copings fabricated using direct metal laser sintering technique exhibited best marginal accuracy and internal fit. Comparison of mean between the four groups by ANOVA and post-hoc Tukey HSD tests showed a statistically significant difference between all the groups (p⟨0.05). It was concluded that the copings fabricated using direct metal laser sintering technique exhibited best marginal accuracy and internal fit. Additive digital technologies such as direct metal laser sintering could be cost-effective for the clinician, minimize failures related to fit and increase longevity of teeth and prostheses. Copyright© 2017 Dennis Barber Ltd.

  11. Assessment of enamel demineralization using conventional, digital, and digitized radiography Avaliação da desmineralização do esmalte por meio de radiografias convencional, digital e digitalizada

    Directory of Open Access Journals (Sweden)

    Rívea Inês Ferreira

    2006-04-01

    Full Text Available This experimental research aimed at evaluating the accuracy of enamel demineralization detection using conventional, digital, and digitized radiographs, as well as to compare radiographs and logarithmically contrast-enhanced subtraction images. Enamel subsurface demineralization was induced on one of the approximal surfaces of 49 sound third molars. Standardized radiographs of the teeth were taken prior to and after the demineralization phase with three digital systems - CygnusRay MPS®, DenOptix® and DIGORA® - and InSight® film. Three radiologists interpreted the pairs of conventional, digital, and digitized radiographs in two different occasions. Logarithmically contrast-enhanced subtraction images were examined by a fourth radiologist only once. Radiographic diagnosis was validated by cross-sectional microhardness profiling in the test areas of the approximal surfaces. Accuracy was estimated by Receiver Operating Characteristic (ROC analysis. Chi-square test, at a significance level of 5%, was used to compare the areas under the ROC curves (Az calculated for the different imaging modalities. Concerning the radiographs, the DenOptix® system (Az = 0.91 and conventional radiographs (Az = 0.90 presented the highest accuracy values compared with the other three radiographic modalities. However, logarithmically contrast-enhanced subtraction images (Az = 0.98 were significantly more accurate than conventional, digital, and digitized radiographs (p = 0.0000. It can be concluded that the DenOptix® system and conventional radiographs provide better performance for diagnosing enamel subsurface demineralization. Logarithmic subtraction significantly improves radiographic detection.O objetivo desta pesquisa experimental foi investigar a acurácia da detecção de desmineralizações em esmalte por meio de radiografias convencionais, digitais e digitalizadas, e compará-las às imagens por subtração logarítmica. Foram induzidas desmineraliza

  12. Diagnostic yield and accuracy of CT angiography, MR angiography, and digital subtraction angiography for detection of macrovascular causes of intracerebral haemorrhage: prospective, multicentre cohort study

    OpenAIRE

    van Asch, Charlotte J. J.; Birgitta K Velthuis; Rinkel, Gabriël J E; Algra, Ale; de Kort, Gerard A. P.; Witkamp, Theo D.; de Ridder, Johanna C M; van Nieuwenhuizen, Koen M.; De Leeuw, Frank Erik; Schonewille, Wouter J.; de Kort, Paul L. M.; Dippel, Diederik W; Raaymakers, Theodora W M; Hofmeijer, Jeannette; Wermer, Marieke J. H.

    2015-01-01

    Study question What are the diagnostic yield and accuracy of early computed tomography (CT) angiography followed by magnetic resonance imaging/angiography (MRI/MRA) and digital subtraction angiography (DSA) in patients with non-traumatic intracerebral haemorrhage? Methods This prospective diagnostic study enrolled 298 adults (18-70 years) treated in 22 hospitals in the Netherlands over six years. CT angiography was performed within seven days of haemorrhage. If the result was negative, MRI/MR...

  13. Pedal angiography in peripheral arterial occlusive disease: first-pass i.v. contrast-enhanced MR angiography with blood pool contrast medium versus intraarterial digital subtraction angiography.

    Science.gov (United States)

    Kos, Sebastian; Reisinger, Clemens; Aschwanden, Markus; Bongartz, Georg M; Jacob, Augustinus L; Bilecen, Deniz

    2009-03-01

    The purpose of this study was to prospectively evaluate first-pass i.v. gadofosveset-enhanced MR angiography in patients with peripheral arterial occlusive disease for visualization of the pedal arteries and stenosis or occlusion of those arteries with intraarterial digital subtraction angiography as the reference standard. Twenty patients with peripheral arterial occlusive disease (nine women, 11 men; age-range 58-83 years) were prospectively enrolled. Gadofosveset first-pass contrast-enhanced MR angiography was performed with a 1.5-T system, a dedicated foot coil, and cuff compression to the calf. Arterial segments were assessed for degree of arterial stenosis, arterial visibility, diagnostic utility, and venous contamination. Detection of vessel stenosis or occlusion was evaluated in comparison with findings at digital subtraction angiography. The unpaired Student's t test was used to test arterial visibility with the two techniques. First-pass MR angiography with gadofosveset had good diagnostic utility in 83.9% of all segments and no venous contamination in 96.8% of all segments. There was no difference between the performance of intraarterial digital subtraction angiography and that of i.v. contrast-enhanced MR angiography in arterial visibility overall (p = 0.245) or in subgroup analysis of surgical arterial bypass targets (p = 0.202). The overall sensitivity, specificity, and accuracy of i.v. gadofosveset-enhanced MR angiography for characterization of clinically significant stenosis and occlusion were 91.4%, 96.1%, and 93.9%. In the subgroup analysis, the sensitivity, specificity, and accuracy were 85.5%, 96.5%, and 92.1%. Gadofosveset-enhanced MR angiography of the pedal arteries in patients with peripheral arterial occlusive disease has arterial visibility equal to that of digital subtraction angiography and facilitates depiction of clinically significant stenosis and occlusion.

  14. Follow-up after embolization of ruptured intracranial aneurysms: A prospective comparison of two-dimensional digital subtraction angiography, three-dimensional digital subtraction angiography, and time-of-flight magnetic resonance angiography

    Energy Technology Data Exchange (ETDEWEB)

    Serafin, Zbigniew; Strzesniewski, Piotr; Lasek, Wladyslaw [Nicolaus Copernicus University, Collegium Medicum, Department of Radiology and Diagnostic Imaging, Bydgoszcz (Poland); Beuth, Wojciech [Nicolaus Copernicus University, Collegium Medicum, Department of Neurosurgery and Neurotraumatology, Bydgoszcz (Poland)

    2012-11-15

    To prospectively compare of the diagnostic value of digital subtraction angiography (DSA) and time-of-flight magnetic resonance angiography (TOF-MRA) in the follow-up of intracranial aneurysms after endovascular treatment. Seventy-two consecutive patients were examined 3 months after the embolization. The index tests included: two-dimensional DSA (2D-DSA), three-dimensional DSA (3D-DSA), and TOF-MRA. The reference test was a retrospective consensus between 2D-DSA images, 3D-DSA images, and source rotational DSA images. The evaluation included: detection of the residual flow, quantification of the flow, and validity of the decision regarding retreatment. Intraobserver agreement and interobserver agreement were determined. The sensitivity and specificity of residual flow detection ranged from 84.6 % (2D-DSA and TOF-MRA) to 92.3 % (3D-DSA) and from 91.3 % (TOF-MRA) to 97.8 % (3D-DSA), respectively. The accuracy of occlusion degree evaluation ranged from 0.78 (2D-DSA) to 0.92 (3D-DSA, Cohen's kappa). The 2D-DSA method presented lower performance in the decision on retreatment than 3D-DSA (P < 0.05, ROC analysis). The intraobserver agreement was very good for all techniques ({kappa} = 0.80-0.97). The interobserver agreement was moderate for TOF-MRA and very good for 2D-DSA and 3D-DSA ({kappa} = 0.72-0.94). Considering the invasiveness of DSA and the minor difference in the diagnostic performance between 3D-DSA and TOF-MRA, the latter method should be the first-line modality for follow-up after aneurysm embolization. (orig.)

  15. An automatic fuzzy-based multi-temporal brain digital subtraction angiography image fusion algorithm using curvelet transform and content selection strategy.

    Science.gov (United States)

    Momeni, Saba; Pourghassem, Hossein

    2014-08-01

    Recently image fusion has prominent role in medical image processing and is useful to diagnose and treat many diseases. Digital subtraction angiography is one of the most applicable imaging to diagnose brain vascular diseases and radiosurgery of brain. This paper proposes an automatic fuzzy-based multi-temporal fusion algorithm for 2-D digital subtraction angiography images. In this algorithm, for blood vessel map extraction, the valuable frames of brain angiography video are automatically determined to form the digital subtraction angiography images based on a novel definition of vessel dispersion generated by injected contrast material. Our proposed fusion scheme contains different fusion methods for high and low frequency contents based on the coefficient characteristic of wrapping second generation of curvelet transform and a novel content selection strategy. Our proposed content selection strategy is defined based on sample correlation of the curvelet transform coefficients. In our proposed fuzzy-based fusion scheme, the selection of curvelet coefficients are optimized by applying weighted averaging and maximum selection rules for the high frequency coefficients. For low frequency coefficients, the maximum selection rule based on local energy criterion is applied to better visual perception. Our proposed fusion algorithm is evaluated on a perfect brain angiography image dataset consisting of one hundred 2-D internal carotid rotational angiography videos. The obtained results demonstrate the effectiveness and efficiency of our proposed fusion algorithm in comparison with common and basic fusion algorithms.

  16. Comparative evaluation of 64-slice CT angiography and digital subtraction angiography in assessing the cervicocranial vasculature

    Directory of Open Access Journals (Sweden)

    Randolf Klingebiel

    2008-08-01

    Full Text Available Randolf Klingebiel1, Max Kentenich3, Hans-Christian Bauknecht3, Florian Masuhr2, Eberhard Siebert1, Markus Busch2, Georg Bohner11Department of Neuroradiology, 2Department of Neurology, 3Department of Radiology, Charité Universitary Medicine Berlin, GermanyBackground: Noninvasive 64-slice computed tomography angiography (64-MSCTA closely approximates conventional catheter angiography (DSA in terms of detail resolution. Objective: Retrospective evaluation of cervicocranial (cc 64-MSCTA in comparison with DSA in patients with presumptive cc vascular disorders.Material and methods: Twenty-four 64-MSCTA studies (32 mm detector width, slice thickness 0.5 mm, 120 kv, 150 mAs, pitch 0.75 of patients with presumptive cc vascular pathology (13 men, 11 women, mean age 38.3 ± 11.3 yrs, range 19–54 yrs were assessed in comparison with DSA studies without abnormal findings in age-matched patients (11 men, 13 women, mean age 39.7 ± 11.9 yrs, range 18–54 yrs. Study readings were performed in a blinded manner by two neuroradiologists with respect to image quality and assessibility of various cc vascular segments by using a five-point scale. Radiation exposure was calculated for 64-MSCTA.Results: Each reader assessed 384/528 different vessel segments (64-MSCTA/DSA. Superior image quality was attributed to DSA with respect to the C1 ICA–C6 ICA, A3 ACA, and P3 PCA segments as well the AICA and SCA. 64-MSCTA was scored superior for C7 ICA and V4 VA segments. A significantly increased number of nonassessable V2- and V3 VA segments in DSA studies was noted. The effective dose for 64-MSCTA amounted to 2.2 mSv.Conclusions: 64-MSCTA provides near-equivalent diagnostic information of the cc vasculature as compared with DSA. According to our results, DSA should be considered primarily when peripheral vessels (A3/P3 or ICA segments close to the skull base (C2-5 are of interest, such as in primary angiitis or stenoocclusive ICA disease, respectively.Keywords: CT

  17. Effect of injection technique on temporal parametric imaging derived from digital subtraction angiography in patient specific phantoms

    Science.gov (United States)

    Ionita, Ciprian N.; Garcia, Victor L.; Bednarek, Daniel R.; Snyder, Kenneth V.; Siddiqui, Adnan H.; Levy, Elad I.; Rudin, Stephen

    2014-03-01

    Parametric imaging maps (PIM's) derived from digital subtraction angiography (DSA) for the cerebral arterial flow assessment in clinical settings have been proposed, but experiments have yet to determine the reliability of such studies. For this study, we have observed the effects of different injection techniques on PIM's. A flow circuit set to physiologic conditions was created using an internal carotid artery phantom. PIM's were derived for two catheter positions, two different contrast bolus injection volumes (5ml and 10 ml), and four injection rates (5, 10, 15 and 20 ml/s). Using a gamma variate fitting approach, we derived PIM's for mean-transit-time (MTT), time-to-peak (TTP) and bolus-arrivaltime (BAT). For the same injection rates, a larger bolus resulted in an increased MTT and TTP, while a faster injection rate resulted in a shorter MTT, TTP, and BAT. In addition, the position of the catheter tip within the vasculature directly affected the PIM. The experiment showed that the PIM is strongly correlated with the injection conditions, and, therefore, they have to be interpreted with caution. PIM images must be taken from the same patient to be able to be meaningfully compared. These comparisons can include pre- and post-treatment images taken immediately before and after an interventional procedure or simultaneous arterial flow comparisons through the left and right cerebral hemispheres. Due to the strong correlation between PIM and injection conditions, this study indicates that this assessment method should be used only to compare flow changes before and after treatment within the same patient using the same injection conditions.

  18. Comparison of contrast-enhanced multi-station MR angiography and digital subtraction angiography of the lower extremity arterial disease.

    Science.gov (United States)

    Burbelko, Mykhaylo; Augsten, Michael; Kalinowski, Marc O; Heverhagen, Johannes T

    2013-06-01

    To compare diagnostic accuracy of multi-station, high-spatial resolution contrast-enhanced MR angiography (CE-MRA) of the lower extremities with digital subtraction angiography (DSA) as the reference standard in patients with symptomatic peripheral arterial occlusive disease. Of 485 consecutive patients undergoing a run-off CE-MRA, 152 patients (86 male, 66 female; mean age, 71.6 years) with suspected peripheral arterial occlusive disease were included into our Institutional Review Board approved study. All patients underwent MRA and DSA of the lower extremities within 30 days. MRA was performed at 1.5 Tesla with a single bolus of 0.1 mmol/kg body weight of gadobutrol administered at a rate of 2.0 mL/s at three stations. Two readers evaluated the MRA images independently for stenosis grade and image quality. Sensitivity and specificity were derived. Sensitivity and specificity ranged from 73% to 93% and 64% to 89% and were highest in the thigh area. Both readers showed comparable results. Evaluation of good and better quality MRAs resulted in a considerable improvement in diagnostic accuracy. Contrast-enhanced MRA demonstrates good sensitivity and specificity in the investigation of the vasculature of the lower extremities. While a minor investigator experience dependence remains, it is standardizable and shows good inter-observer agreement. Our results confirm that the administration of Gadobutrol at a standard dose of 0.1 mmol/kg for contrast-enhanced runoff MRA is able to detect hemodynamically relevant stenoses. Use of contrast-enhanced MRA as an alternative to intra-arterial DSA in the evaluation and therapeutic planning of patients with suspected peripheral arterial occlusive disease is well justified. Copyright © 2012 Wiley Periodicals, Inc.

  19. Intra-Arterial MR Perfusion Imaging of Meningiomas: Comparison to Digital Subtraction Angiography and Intravenous MR Perfusion Imaging

    Science.gov (United States)

    Martin, Alastair J.; Alexander, Matthew D.; McCoy, David B.; Cooke, Daniel L.; Lillaney, Prasheel; Moftakhar, Parham; Amans, Matthew R.; Settecase, Fabio; Nicholson, Andrew; Dowd, Christopher F.; Halbach, Van V.; Higashida, Randall T.; McDermott, Michael W.; Saloner, David; Hetts, Steven W.

    2016-01-01

    Background and Purpose To evaluate the ability of IA MR perfusion to characterize meningioma blood supply. Methods Studies were performed in a suite comprised of an x-ray angiography unit and 1.5T MR scanner that permitted intraprocedural patient movement between the imaging modalities. Patients underwent intra-arterial (IA) and intravenous (IV) T2* dynamic susceptibility MR perfusion immediately prior to meningioma embolization. Regional tumor arterial supply was characterized by digital subtraction angiography and classified as external carotid artery (ECA) dural, internal carotid artery (ICA) dural, or pial. MR perfusion data regions of interest (ROIs) were analyzed in regions with different vascular supply to extract peak height, full-width at half-maximum (FWHM), relative cerebral blood flow (rCBF), relative cerebral blood volume (rCBV), and mean transit time (MTT). Linear mixed modeling was used to identify perfusion curve parameter differences for each ROI for IA and IV MR imaging techniques. IA vs. IV perfusion parameters were also directly compared for each ROI using linear mixed modeling. Results 18 ROIs were analyzed in 12 patients. Arterial supply was identified as ECA dural (n = 11), ICA dural (n = 4), or pial (n = 3). FWHM, rCBV, and rCBF showed statistically significant differences between ROIs for IA MR perfusion. Peak Height and FWHM showed statistically significant differences between ROIs for IV MR perfusion. RCBV and MTT were significantly lower for IA perfusion in the Dural ECA compared to IV perfusion. Relative CBF in IA MR was found to be significantly higher in the Dural ICA region and MTT significantly lower compared to IV perfusion. PMID:27802268

  20. [Conventional radiology, digital radiology with photostimulable phosphor, laser digitalization of thoracic radiographic films at the bedside. A comparative study].

    Science.gov (United States)

    Miceli, M; Stamati, R; Burci, P; Guidarelli, G; Sartoni Galloni, S

    1992-10-01

    The bedside chest images obtained with conventional radiology and with "on line" and "off line" digital modalities were compared to evaluate the respective capabilities in visualizing chest anatomical structures. Seventy patients were submitted to bedside chest examinations with a portable unit; both a conventional film and a digital system (PCR Graphics 1, Philips) with photostimulable phosphor imaging plate were fitted in the radiographic cassette. The former was digitized using an "off line" laser beam unit (FD 2000, Dupont); the latter was subsequently postprocessed by modifying contrast, optical density and spatial frequencies. Thus, 4 different viewing modalities were obtained for each examination: a) conventional radiography; b) standard digital radiography; c) postprocessed digital radiography; d) digitized conventional radiography. Detectability rates of chest anatomical structures were analyzed by 4 independent radiologists on the different images and expressed by a score 1-4. The values were always higher with digital modalities than with the conventional one and the differences were statistically significant (Student's t-test modified by Bonferroni). In particular, the greatest difference was found between c) and a) in retrocardiac lung parenchyma and in skeletal structures, in favour of c). Concerning the comparative adequacy of the various digital modalities, higher detectability rates of chest anatomical structures were obtained with c), but also with b), than with d).

  1. Theoretical and experimental comparison of image signal and noise for dual-energy subtraction angiography and conventional x-ray angiography

    Science.gov (United States)

    Burton, Christiane S.; Mayo, John R.; Cunningham, I. A.

    2015-03-01

    Cardiovascular disease is currently the leading cause of mortality worldwide. Digital subtraction angiography (DSA) is widely used to enhance the visibility of small vessels and vasculature obscurred by overlying bone and lung fields by subtracting a mask and contrast image. However, motion between these mask and contrast images can introduce artifacts that can render a study non-diagnostic. This makes DSA particularly unsuccessful for cardiac imaging. A method called dual-energy, or energy subtraction angiography (ESA), was proposed in the past as an alternative for vascular imaging, however it was not pursued because experimental results suggested that image quality was deemed as poor and inferior to DSA. Image quality for angiography comes down to iodine signal and noise. In this paper we investigate the fundamental iodine signal and noise analysis of ESA and compare it to DSA. Method: We developed a polyenergetic and monoenergetic theoretical model for iodine signal and noise for both ESA and DSA. We validated our polyenergetic model by experiment where ESA and DSA images of a vascular phantom were acquired using an x-ray system with a flat panel CsI Xmaru1215CF-MPTM (Rayence Co., Ltd., Republic of Korea) detector. For ESA low and high applied tube voltages of 50 kV and 120 kV (2.5 mmCu), respectively, and for DSA the applied tube voltage was 80 kV. Iodine signal-to-noise ratio (SNR) per entrance exposure was calculated for each iodine concentration for both ESA and DSA. Results: Our measured iodine SNR agreed well with theoretical calculations. Iodine SNR for ESA was relatively higher than DSA for low iodine mass loadings, and as iodine mass loading increases iodine SNR decreases. Conclusions: We have developed a model for iodine SNR for both DSA and ESA. Our model was validated with experiment and showed excellent agreement. We have shown that there is potential for obtaining iodine-specific images using ESA that are similar to DSA.

  2. Sensor noise in direct digital imaging (the RadioVisioGraphy, Sens-a-Ray, and Visualix/Vixa systems) evaluated by subtraction radiography.

    Science.gov (United States)

    Wenzel, A

    1994-01-01

    The aim of this study was to evaluate sensor noise with the use of the subtraction method in radiographs captured with three direct digital intraoral systems. Ten radiographs were taken of the lower left molar region of a phantom head at each of three exposure times: 0.20 seconds, 0.46 seconds, and 0.60 seconds with the use of the RadioVisioGraphy (Trophy Radiologie, Vincennes, France), Sens-a-Ray (Regam Medical Systems, AB, Sundsvall, Sweden), and Visualix (Gendex, Philips Medical Systems, Inc., Monza, Italy) systems. Neither the x-ray tube nor the phantom were moved between exposures, and the three sensors were identically positioned. The images were stored in the tagged image file format provided by the systems in 8-bit depth and imported by a subtraction program. Subtractions were performed between identical images taken with the three systems. The standard deviation for the distribution of the shades of grey in the subtraction image histogram served as an expression for image noise. Paired t tests evaluated differences between the standard deviations of the subtraction images from the three systems. The standard deviation increased with increasing exposure time for all three systems (p < 0.00001). The standard deviation for the images performed with Visualix were 6.47, 10.34, and 11.16 at exposure times 0.20, 0.46, and 0.60, respectively. For the RadioVisioGraphy, these values were 1.61, 2.03, and 2.18, and for Sens-a-Ray 2.90, 3.98, and 3.96, respectively. The differences between the systems were highly statistically significant (p < 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

  3. Comparison of C-arm Computed Tomography and Digital Subtraction Angiography in Patients with Chronic Thromboembolic Pulmonary Hypertension

    Energy Technology Data Exchange (ETDEWEB)

    Hinrichs, Jan B., E-mail: hinrichs.jan@mh-hannover.de; Marquardt, Steffen, E-mail: marquardt.steffen@mh-hannover.de; Falck, Christian von, E-mail: falck.christian.von@mh-hannover.de [Hannover Medical School, Department for Diagnostic and Interventional Radiology, German Center for Lung Research (DZL) (Germany); Hoeper, Marius M., E-mail: hoeper.marius@mh-hannover.de; Olsson, Karen M., E-mail: olsson.karen@mh-hannover.de [Hannover Medical School, Clinic for Pneumology, German Center for Lung Research (DZL) (Germany); Wacker, Frank K., E-mail: wacker.frank@mh-hannover.de; Meyer, Bernhard C., E-mail: meyer.bernhard@mh-hannover.de [Hannover Medical School, Department for Diagnostic and Interventional Radiology, German Center for Lung Research (DZL) (Germany)

    2016-01-15

    PurposeTo assess the feasibility and diagnostic performance of contrast-enhanced, C-arm computed tomography (CACT) of the pulmonary arteries compared to digital subtraction angiography (DSA) in patients suffering from chronic thromboembolic pulmonary hypertension (CTEPH).MaterialsFifty-two patients with CTEPH underwent ECG-gated DSA and contrast-enhanced CACT. Two readers (R1, R2) independently evaluated pulmonary artery segments and their sub-segmental branching using DSA and CACT for optimal image quality. Afterwards, the diagnostic findings, i.e., intraluminal filling defects, stenosis, and occlusion, were compared. Inter-modality and inter-observer agreement was calculated, and subsequently consensus reading was done and correlated to a reference standard representing the overall consensus of both modalities. Fisher’s exact test and Cohen’s Kappa were applied.ResultsA total of 1352 pulmonary segments were evaluated, of which 1255 (92.8 %) on DSA and 1256 (92.9 %) on CACT were rated to be fully diagnostic. The main causes of the non-diagnostic image quality were motion artifacts on CACT (R1:37, R2:78) and insufficient contrast enhancement on DSA (R1:59, R2:38). Inter-observer agreement was good for DSA (κ = 0.74) and CACT (κ = 0.75), while inter-modality agreement was moderate (R1: κ = 0.46, R2: κ = 0.47). Compared to the reference standard, the inter-modality agreement for CACT was excellent (κ = 0.96), whereas it was inferior for DSA (κ = 0.61) due to the higher number of abnormal consensus findings read as normal on DSA.ConclusionCACT of the pulmonary arteries is feasible and provides additional information to DSA. CACT has the potential to improve the diagnostic work-up of patients with CTEPH and may be particularly useful prior to surgical or interventional treatment.

  4. Inter- and intra-rater agreement in the assessment of the vascularity of spinal metastases using digital subtraction angiography tumor blush

    DEFF Research Database (Denmark)

    Clausen, Caroline; Dahl, Benny; Christiansen Frevert, Susanne;

    2016-01-01

    Background: Preoperative embolization is based on the preoperative digital subtraction angiography (DSA) tumor blush, and as such is considered the “gold standard” for determining tumor vascularity. However, to our knowledge reliability studies evaluating vascularity ratings of DSA tumor blush...... in spinal metastases have not been published previously. Purpose: To evaluate inter- and intra-rater agreement in the assessment of the vascularity of spinal metastases using DSA tumor blush. Material and Methods: This reliability study included 46 patients with symptomatic metastatic spinal cord...

  5. Reproducibility between conventional and digital periapical radiography for bone height measurement

    OpenAIRE

    Miguel Simancas-Pallares; Jorge Andrés Rubio-Romero; Edgar Cortés-Reyes

    2015-01-01

    Background. Several diagnostic aids are available for bone height measurement. Digital and conventional radiographs are the two ones most used in Dentistry. Few studies accounting for accuracy and precision have been conducted to compare these methods. Objective. The aim of this study was to estimate reproducibility between conventional and digital periapical radiography in bone height measurement in patients with chronic periodontitis. Methods. a consistency diagnostic test study was perform...

  6. Identification of Students' Intuitive Mental Computational Strategies for 1, 2 and 3 Digits Addition and Subtraction: Pedagogical and Curricular Implications

    Science.gov (United States)

    Ghazali, Munirah; Alias, Rohana; Ariffin, Noor Asrul Anuar; Ayub, Ayminsyadora

    2010-01-01

    This paper reports on a study to examine mental computation strategies used by Year 1, Year 2, and Year 3 students to solve addition and subtraction problems. The participants in this study were twenty five 7 to 9 year-old students identified as excellent, good and satisfactory in their mathematics performance from a school in Penang, Malaysia.…

  7. Identification of Students' Intuitive Mental Computational Strategies for 1, 2 and 3 Digits Addition and Subtraction: Pedagogical and Curricular Implications

    Science.gov (United States)

    Ghazali, Munirah; Alias, Rohana; Ariffin, Noor Asrul Anuar; Ayub, Ayminsyadora

    2010-01-01

    This paper reports on a study to examine mental computation strategies used by Year 1, Year 2, and Year 3 students to solve addition and subtraction problems. The participants in this study were twenty five 7 to 9 year-old students identified as excellent, good and satisfactory in their mathematics performance from a school in Penang, Malaysia.…

  8. A comparison between magnetic resonance angiography at 3 teslas (time-of-flight and contrast-enhanced and flat-panel digital subtraction angiography in the assessment of embolized brain aneurysms

    Directory of Open Access Journals (Sweden)

    Guilherme S. Nakiri

    2011-01-01

    Full Text Available PURPOSE: To compare the time-of-flight and contrast-enhanced- magnetic resonance angiography techniques in a 3 Tesla magnetic resonance unit with digital subtraction angiography with the latest flat-panel technology and 3D reconstruction in the evaluation of embolized cerebral aneurysms. INTRODUCTION: Many embolized aneurysms are subject to a recurrence of intra-aneurismal filling. Traditionally, imaging surveillance of coiled aneurysms has consisted of repeated digital subtraction angiography. However, this method has a small but significant risk of neurological complications, and many authors have advocated the use of noninvasive imaging methods for the surveillance of embolized aneurysms. METHODS: Forty-three aneurysms in 30 patients were studied consecutively between November 2009 and May 2010. Two interventional neuroradiologists rated the time-of-flight-magnetic resonance angiography, the contrast-enhanced-magnetic resonance angiography, and finally the digital subtraction angiography, first independently and then in consensus. The status of aneurysm occlusion was assessed according to the Raymond scale, which indicates the level of recanalization according to degrees: Class 1: excluded aneurysm; Class 2: persistence of a residual neck; Class 3: persistence of a residual aneurysm. The agreement among the analyses was assessed by applying the Kappa statistic. RESULTS: Inter-observer agreement was excellent for both methods (K = 0.93; 95 % CI: 0.84-1. Inter-technical agreement was almost perfect between time-of-flight-magnetic resonance angiography and digital subtraction angiography (K = 0.98; 95 % CI: 0.93-1 and between time-of-flight-magnetic resonance angiography and contrast-enhanced-magnetic resonance angiography (K = 0.98; 95% CI: 0.93-1. Disagreement occurred in only one case (2.3%, which was classified as Class I by time-of-flight-magnetic resonance angiography and Class II by digital subtraction angiography. The agreement between

  9. Subtracted geometry

    Science.gov (United States)

    Saleem, Zain Hamid

    In this thesis we study a special class of black hole geometries called subtracted geometries. Subtracted geometry black holes are obtained when one omits certain terms from the warp factor of the metric of general charged rotating black holes. The omission of these terms allows one to write the wave equation of the black hole in a completely separable way and one can explicitly see that the wave equation of a massless scalar field in this slightly altered background of a general multi-charged rotating black hole acquires an SL(2, R) x SL(2, R) x SO(3) symmetry. The "subtracted limit" is considered an appropriate limit for studying the internal structure of the non-subtracted black holes because new 'subtracted' black holes have the same horizon area and periodicity of the angular and time coordinates in the near horizon regions as the original black hole geometry it was constructed from. The new geometry is asymptotically conical and is physically similar to that of a black hole in an asymptotically confining box. We use the different nice properties of these geometries to understand various classically and quantum mechanically important features of general charged rotating black holes.

  10. A new method for analyzing auditory brain-stem response waveforms using a moving-minimum subtraction procedure of digitized analog recordings

    Directory of Open Access Journals (Sweden)

    Källstr

    2014-06-01

    Full Text Available Johan Källstrand,1 Tommy Lewander,2 Eva Baghdassarian,2,3 Sören Nielzén4 1SensoDetect AB, Lund, 2Department of Neuroscience, Medical Faculty, Uppsala University, 3Department of Psychiatry, Uppsala University Hospital, Uppsala, 4Department of Psychiatry, Medical Faculty, University of Lund, Lund, Sweden Abstract: The auditory brain-stem response (ABR waveform comprises a set of waves (labeled I–VII recorded with scalp electrodes over 10 ms after an auditory stimulation with a brief click sound. Quite often, the waves are fused (confluent and baseline-irregular and sloped, making wave latencies and wave amplitudes difficult to establish. In the present paper, we describe a method, labeled moving-minimum subtraction, based on digitization of the analog ABR waveform (154 data points/ms in order to achieve alignment of the ABR response to a straight baseline, often with clear baseline separation of waves and resolution of fused waves. Application of the new method to groups of patients showed marked differences in ABR waveforms between patients with schizophrenia versus patients with adult attention deficit/hyperactivity disorder versus healthy controls. The findings show promise regarding the possibility to identify ABR markers to be used as biomarkers as support for clinical diagnoses of these and other neuropsychiatric disorders. Keywords: auditory brain-stem response, digitization, moving-minimum subtraction method, baseline alignment, schizophrenia, ADHD

  11. Using digital subtraction in computer simulated images as a tool to aid the visual detection of masked lesions in dense breasts

    Science.gov (United States)

    Schiabel, Homero; Guimarães, Luciana T.; Sousa, Maria A. Z.

    2015-03-01

    This work proposes a simulation model involving subtraction of digital mammography images obtained at different X-ray beam levels of energy to aid the detection of breast malignant lesions. Absorption coefficients behavior of 3 main structures of clinical interest - adipose tissue, fiber glandular tissue and the typical carcinoma - as a function of the beam energy from a Mo X-ray tube was the basis to develop a computer simulation of the possible acquired images. The simulation has considered a typical compressed breast with 4.5cm in thickness, and variations of the carcinoma and glandular tissues thicknesses - 0.4 up to 2.0cm and 4.1 to 2.5cm, respectively - were evaluated as a function of the photons mean energy - 14 up to 25 keV, in the typical mammography energy range. Results have shown that: (a) if the carcinoma thickness is over 0.4cm, its detection may be feasible even masked by fiber tissue with exposures in the range of 19 to 25 keV; (b) for masked carcinoma with thickness in the range of 0.4-2.0cm, the proposed procedure can enhance it in the image resulting from the digital subtraction between images obtained at 14 and at 22 keV. Therefore such results indicate that this simulation procedure can be a useful tool in aiding the identification of possible missed malignant lesions which could not be detected in the typical exam, mainly considering dense breasts.

  12. Image quality assessment in panoramic dental radiography: a comparative study between conventional and digital systems.

    Science.gov (United States)

    Sabarudin, Akmal; Tiau, Yu Jin

    2013-02-01

    This study is designed to compare and evaluate the diagnostic image quality of dental panoramic radiography between conventional and digital systems. Fifty-four panoramic images were collected and divided into three groups consisting of conventional, digital with and without post processing image. Each image was printed out and scored subjectively by two experienced dentists who were blinded to the exposure parameters and system protocols. The evaluation covers of anatomical coverage and structures, density and image contrast. The overall image quality score revealed that digital panoramic with post-processing scored the highest of 3.45±0.19, followed by digital panoramic system without post-processing and conventional panoramic system with corresponding scores of 3.33±0.33 and 2.06±0.40. In conclusion, images produced by digital panoramic system are better in diagnostic image quality than that from conventional panoramic system. Digital post-processing visualization can improve diagnostic quality significantly in terms of radiographic density and contrast.

  13. Comparison of radiographic measurements obtained with conventional an indirect digital imaging during endontic treatment

    Directory of Open Access Journals (Sweden)

    Ligia Buloto Schmitd

    2008-04-01

    Full Text Available The aims of this study were to evaluate the quality of indirect digitized radiographic images taken during endodontic procedures and to compare the measurements recorded with this technique to those obtained from conventional radiographs. Two-hundred conventional periapical radiographs taken at the undergraduate Endodontics Clinic of the Dental School of Bauru were digitized. The conventional and indirect digitized images were compared by three examiners as to the quality and accuracy of the measurements recorded during endodontic treatment, in canal length determination, gutta-percha adaptation, lateral condensation and final obturation. The conventional radiographs were observed on a film viewer, surrounded by a dark card, and measured with magnifying glass and a millimeter ruler; the indirect digitized images were evaluated on the Digora® for Windows software, with free utilization of the bright/contrast tool. Unlike the conventional radiographic images, all indirect digitized images were considered as having a high quality. The distance between the filling material and the root apex was 0.117 mm larger, on average, for the Digora® system (p<0.01. The measurements achieved by the investigated radiographic methods were clinically similar and they are thus equivalent. Changes in brightness and contrast of the images using Digora®software improved the diagnosis.

  14. COMPARISON OF RADIOGRAPHIC MEASUREMENTS OBTAINED WITH CONVENTIONAL AND INDIRECT DIGITAL IMAGING DURING ENDODONTIC TREATMENT

    Science.gov (United States)

    Schmitd, Ligia Buloto; Lima, Tatiana de Castro; Chinellato, Luiz Eduardo Montenegro; Bramante, Clóvis Monteiro; Garcia, Roberto Brandão; de Moraes, Ivaldo Gomes; Bernardineli, Norberti

    2008-01-01

    The aims of this study were to evaluate the quality of indirect digitized radiographic images taken during endodontic procedures and to compare the measurements recorded with this technique to those obtained from conventional radiographs. Two-hundred conventional periapical radiographs taken at the undergraduate Endodontics Clinic of the Dental School of Bauru were digitized. The conventional and indirect digitized images were compared by three examiners as to the quality and accuracy of the measurements recorded during endodontic treatment, in canal length determination, gutta-percha adaptation, lateral condensation and final obturation. The conventional radiographs were observed on a film viewer, surrounded by a dark card, and measured with magnifying glass and a millimeter ruler; the indirect digitized images were evaluated on the Digora® for Windows software, with free utilization of the bright/contrast tool. Unlike the conventional radiographic images, all indirect digitized images were considered as having a high quality. The distance between the filling material and the root apex was 0.117 mm larger, on average, for the Digora® system (p<0.01). The measurements achieved by the investigated radiographic methods were clinically similar and they are thus equivalent. Changes in brightness and contrast of the images using Digora® software improved the diagnosis. PMID:19089211

  15. Image subtraction by solid state electroradiography

    Energy Technology Data Exchange (ETDEWEB)

    Fallone, B.G.; Podgorsak, E.B. (McGill Univ., Montreal, Quebec (Canada). Dept. of Radiation Oncology; McGill Univ., Montreal, Quebec (Canada). Dept. of Diagnostic Radiology)

    1984-06-01

    An analog radiographic image subtraction technique is presented. A selenium photoconductor is used as the radiation sensitive medium and image subtraction is achieved by electrostatically adding latent images of opposite polarities to get a latent image of the region of interest. In principle, the technique is simple and a comparison with commercial digital techniques shows a similar image quality, suggesting that the electrostatic subtraction technique could be developed into a clinical tool as an inexpensive alternative to digital radiography.

  16. Conventional Versus Digital Radiography in Detecting Root Canal Type in Maxillary Premolars: An in Vitro Study

    Directory of Open Access Journals (Sweden)

    Mahkameh Moshfeghi

    2013-01-01

    Full Text Available Objective: Successful endodontic therapy depends on adequate mechanical and chemical debridement of the canal which requires knowledge of the canal morphology. Conventional radiography has been used to evaluate the canal type; however, direct digital radiography has recently been practiced for this purpose due to the shortcomings of conventional radiography. The aim of the present study was to compare the accuracy of digital and conventional radiography taken at 0° and 30° angles in the diagnosis of the canal type of extracted maxillary premolars.Materials and Methods: This diagnostic study was performed on 90 extracted maxillary premolars. Conventional and digital radiographies were taken of all teeth at 0° and 30° horizontal angles. The images were assessed by an oral and maxillofacial radiologist. The clearing technique was used as the gold standard. The canal type was determined using Weine classification. The agreement between each one of the 4 radiographic modalities and gold standard was determined by kappa statistics.Results: The kappa values for the agreement of parallel conventional, 30° conventional, parallel digital and 30° digital modalities with the clearing technique were 0.059, 0.215, 0.043 and 0.391, respectively. Parallel modalities were unable to determine the tooth canal type. Radiographic images taken at 30° significantly determined the canal type, although only a poor level of agreement was noted between the two modalities and the clearing technique.Conclusion: All modalities had limited value to determine the root canal type in maxillary premolars. However, direct digital imaging taken at 30° angle showed the highest accuracy for canal type assessment.

  17. A novel approach to background subtraction in contrast-enhanced dual-energy digital mammography with commercially available mammography devices: Polychromaticity correction.

    Science.gov (United States)

    Contillo, Adriano; Di Domenico, Giovanni; Cardarelli, Paolo; Gambaccini, Mauro; Taibi, Angelo

    2015-11-01

    Contrast-enhanced digital mammography is an image subtraction technique that is able to improve the detectability of lesions in dense breasts. One of the main sources of error, when the technique is performed by means of commercial mammography devices, is represented by the intrinsic polychromaticity of the x-ray beams. The aim of the work is to propose an iterative procedure, which only assumes the knowledge of a small set of universal quantities, to take into account the polychromaticity and correct the subtraction results accordingly. In order to verify the procedure, it has been applied to an analytical simulation of a target containing a contrast medium and to actual radiographs of a breast phantom containing cavities filled with a solution of the same medium. The reconstructed densities of contrast medium were compared, showing very good agreement between the theoretical predictions and the experimental results already after the first iteration. Furthermore, the convergence of the iterative procedure was studied, showing that only a small number of iterations is necessary to reach limiting values. The proposed procedure represents an efficient solution to the polychromaticity issue, qualifying therefore as a viable alternative to inverse-map functions.

  18. A novel approach to background subtraction in contrast-enhanced dual-energy digital mammography with commercially available mammography devices: Polychromaticity correction

    Energy Technology Data Exchange (ETDEWEB)

    Contillo, Adriano, E-mail: contillo@fe.infn.it; Di Domenico, Giovanni; Cardarelli, Paolo; Gambaccini, Mauro; Taibi, Angelo [Dipartimento di Fisica e Scienze della Terra, Università degli Studi di Ferrara, Via Saragat 1, Ferrara I-44122 (Italy)

    2015-11-15

    Purpose: Contrast-enhanced digital mammography is an image subtraction technique that is able to improve the detectability of lesions in dense breasts. One of the main sources of error, when the technique is performed by means of commercial mammography devices, is represented by the intrinsic polychromaticity of the x-ray beams. The aim of the work is to propose an iterative procedure, which only assumes the knowledge of a small set of universal quantities, to take into account the polychromaticity and correct the subtraction results accordingly. Methods: In order to verify the procedure, it has been applied to an analytical simulation of a target containing a contrast medium and to actual radiographs of a breast phantom containing cavities filled with a solution of the same medium. Results: The reconstructed densities of contrast medium were compared, showing very good agreement between the theoretical predictions and the experimental results already after the first iteration. Furthermore, the convergence of the iterative procedure was studied, showing that only a small number of iterations is necessary to reach limiting values. Conclusions: The proposed procedure represents an efficient solution to the polychromaticity issue, qualifying therefore as a viable alternative to inverse-map functions.

  19. Carbon dioxide (CO{sub 2}) digital subtraction angiography. Evaluation of a new delivery system; Angiografia con anidride carbonica. Nuovo sistema di iniezione

    Energy Technology Data Exchange (ETDEWEB)

    Nicolini, A.; Lovaria, A.; Meregaglia, D. [Ospedale Maggiore IRCCS Policlinico, Milan (Italy). Dipt. di Scienze Radiologiche; Palatresi, S. [Ospedale Maggiore IRCCS Policlinico, Milan (Italy). Ist. di Clinica Medica Generale e Terapia Medica

    2000-02-01

    Purpose of this work is to evaluate the usefulness of a new carbon dioxide (CO{sub 2}) intravascular injection system in digital subtraction angiography. March 1998 to May 1999, 39 patients were submitted to digital subtraction angiography with CO{sub 2} injection by a new delivery system, CO{sub 2}-Angio set, OptiMed, Ettingen, Germany. The patients were 29 men and 10 women, whose age ranged 32 to 76 (mean: 47), 18 of them with absolute or relative contraindications to iodinated contrast media and 6 with poor diagnostic findings at previous conventional angiography. CO{sub 2} was used for comparison with iodinated contrast agents in 4 patients. It was studied the following vascular districts: renal arteries in 9 patients, portal vein in 18, lower limb arteries in 7, upper limb veins in 4. In 1 patient CO{sub 2} angiography was carried out for the diagnosis and interventional treatment, by transcatheter embolization, of a postbioptic arteriovenous renal fistula. During the procedure, arterial blood pressure, EKG status and oxygen saturation were monitored, and subjective sensations recorded in all patients. CO{sub 2} angiography provided adequate visualization of vascular districts and of abnormal findings in 32 cased (82%), while its results were considered insufficient for correct and complete assessment in 7 cases (18%). CO{sub 2}-Angio set delivery system has proved to be a simple and safe tool, particularly suitable for use in patients at risk for allergic reactions to iodinated contrast agents and in those with renal function impairment. Also, the system can help carry out some interventional procedures such as arteriovenous fistula embolization and trans jugular portosystemic shunting. [Italian] Scopo di questo articolo e' verificare la validita' e l'efficacia di un nuovo sistema di iniezione angiografico per anidride carbonica. Da marzo 1998 a maggio 1999 sono stati sottoposti ad angiografia con anidride carbonica mediante sistema non

  20. Behavior Subtraction

    CERN Document Server

    Jodoin, P M; Konrad, J

    2009-01-01

    Background subtraction has been a driving engine for many computer vision and video analytics tasks. Although its many variants exist, they all share the underlying assumption that photometric scene properties are either static or exhibit temporal stationarity. While this works in some applications, the model fails when one is interested in discovering {\\it changes in scene dynamics} rather than those in a static background; detection of unusual pedestrian and motor traffic patterns is but one example. We propose a new model and computational framework that address this failure by considering stationary scene dynamics as a ``background'' with which observed scene dynamics are compared. Central to our approach is the concept of an {\\it event}, that we define as short-term scene dynamics captured over a time window at a specific spatial location in the camera field of view. We compute events by time-aggregating motion labels, obtained by background subtraction, as well as object descriptors (e.g., object size)....

  1. Digital Tracking Observations Can Discover Asteroids Ten Times Fainter than Conventional Searches

    CERN Document Server

    Heinze, Aren; Trollo, Joseph

    2015-01-01

    We describe digital tracking, a method for asteroid searches that greatly increases the sensitivity of a telescope to faint unknown asteroids. It has been previously used to detect faint Kuiper Belt objects using the Hubble Space Telescope and large ground-based instruments, and to find a small, fast-moving asteroid during a close approach to Earth. We complement this earlier work by developing digital tracking methodology for detecting asteroids using large-format CCD imagers. We demonstrate that the technique enables the ground-based detection of large numbers of new faint asteroids. Our methodology resolves or circumvents all major obstacles to the large-scale application of digital tracking for finding main belt and near-Earth asteroids. We find that for both asteroid populations, digital tracking can deliver a factor of ten improvement over conventional searches. Digital tracking has long been standard practice for deep Kuiper Belt surveys, but even there our methodology enables deeper integrations than ...

  2. Nonenhanced peripheral MR-angiography (MRA) at 3 Tesla: evaluation of quiescent-interval single-shot MRA in patients undergoing digital subtraction angiography.

    Science.gov (United States)

    Wagner, Moritz; Knobloch, Gesine; Gielen, Martin; Lauff, Marie-Teres; Romano, Valentina; Hamm, Bernd; Kröncke, Thomas

    2015-04-01

    Quiescent-interval single-shot MRA (QISS-MRA) is a promising nonenhanced imaging technique for assessment of peripheral arterial disease (PAD). Previous studies at 3 Tesla included only very limited numbers of patients for correlation of QISS-MRA with digital subtraction angiography (DSA) as standard of reference (SOR). The aim of this prospective institutional review board-approved study was to compare QISS-MRA at 3 Tesla with DSA in a larger patient group. Our study included 32 consecutive patients who underwent QISS-MRA, contrast-enhanced MRA (CE-MRA), and DSA. Two readers independently performed a per-segment evaluation of QISS-MRA and CE-MRA for image quality and identification of non-significant stenosis (Tesla showed similar diagnostic accuracy in the assessment of PAD. A limitation of QISS-MRA was the lower rate of assessable vessel segments compared to CE-MRA.

  3. Spectrum of results of arterial digital subtraction angiography in patients after renal transplantation. Befundspektrum der arteriellen digitalen Subtraktionsangiographie bei Patienten nach Nierentransplantation

    Energy Technology Data Exchange (ETDEWEB)

    Gruetzner, G. (Heinrich-Heine-Univ., Duesseldorf (Germany). Inst. fuer Diagnostische Radiologie); Bach, D. (Medizinische Klinik und Poliklinik, Duesseldorf (Germany). Abteilung fuer Nephrologie); Fluer, P. (Heinrich-Heine-Univ., Duesseldorf (Germany). Inst. fuer Diagnostische Radiologie); Kniemeyer, H.W. (Chirurgische Klinik und Poliklinik, Duesseldorf (Germany). Abteilung fuer Gefaesschirurgie und Nierentransplantation); Moedder, U. (Heinrich-Heine-Univ., Duesseldorf (Germany). Inst. fuer Diagnostische Radiologie)

    1994-06-01

    Digital subtraction angiography (DSA) was performed in 53 of 417 patients with renal transplants. The incidence of clinical apparent vascular complications was 9.1% of all patients with renal transplants (38/417). The most frequent vascular disorders were formed by arterial stenoses at 5.0% of the cases followed by arterial obstructions in 1.7% of the patients. Rare vascular complications were arteriovenous fistulas (0.7%), aneurysms (0.5%) and venous thrombose (0.2%). Because of the high diagnostic value of intraarterial DSA, all patients with renal transplants with a complicated postoperative course should be eligible for angiographic control. In case of a suspected vascular disorder intraarterial DSA should be performed at an early stage. (orig.)

  4. Comparison of the Absorbed Dose of Target Organs between Conventional and Digital Panoramic Radiography

    Directory of Open Access Journals (Sweden)

    Zohre Reyhani

    2016-09-01

    Full Text Available The purpose of this study was to measure and compare target organ’s exposure by direct digital and conventional panoramic radiography. Dose measurements were carried out on a RANDO phantom, which TLDs were placed into 5 target area: thyroid gland, left and right submandibular and parotid salivary glands. Panoramic radiographs were taken with two conventional (CRANEX Tome, Soredex, Tusula Finland and direct digital devices (CRANEX D, Soredex, Tusula Finland.In total, the phantom was irradiated 30 times in the two systems. The TLDs were then coded and analyzed. T-test of statistical analysis was used to find the correlation. We found statistically significant reduction in absorbed dose of target organs in digital panoramic radiography(P<0.01. The highest absorbed dose was for submandibular gland and the lowest was for thyroid gland. We concluded that can reduce absorbed dose in vital organs.

  5. Behavior subtraction.

    Science.gov (United States)

    Jodoin, Pierre-Marc; Saligrama, Venkatesh; Konrad, Janusz

    2012-09-01

    Background subtraction has been a driving engine for many computer vision and video analytics tasks. Although its many variants exist, they all share the underlying assumption that photometric scene properties are either static or exhibit temporal stationarity. While this works in many applications, the model fails when one is interested in discovering changes in scene dynamics instead of changes in scene's photometric properties; the detection of unusual pedestrian or motor traffic patterns are but two examples. We propose a new model and computational framework that assume the dynamics of a scene, not its photometry, to be stationary, i.e., a dynamic background serves as the reference for the dynamics of an observed scene. Central to our approach is the concept of an event, which we define as short-term scene dynamics captured over a time window at a specific spatial location in the camera field of view. Unlike in our earlier work, we compute events by time-aggregating vector object descriptors that can combine multiple features, such as object size, direction of movement, speed, etc. We characterize events probabilistically, but use low-memory, low-complexity surrogates in a practical implementation. Using these surrogates amounts to behavior subtraction, a new algorithm for effective and efficient temporal anomaly detection and localization. Behavior subtraction is resilient to spurious background motion, such as due to camera jitter, and is content-blind, i.e., it works equally well on humans, cars, animals, and other objects in both uncluttered and highly cluttered scenes. Clearly, treating video as a collection of events rather than colored pixels opens new possibilities for video analytics.

  6. Inter-reader variability in follicular lymphoma grading: Conventional and digital reading.

    Science.gov (United States)

    Lozanski, Gerard; Pennell, Michael; Shana'ah, Arwa; Zhao, Weiqiang; Gewirtz, Amy; Racke, Frederick; Hsi, Eric; Simpson, Sabrina; Mosse, Claudio; Alam, Shadia; Swierczynski, Sharon; Hasserjian, Robert P; Gurcan, Metin N

    2013-01-01

    Pathologists grade follicular lymphoma (FL) cases by selecting 10, random high power fields (HPFs), counting the number of centroblasts (CBs) in these HPFs under the microscope and then calculating the average CB count for the whole slide. Previous studies have demonstrated that there is high inter-reader variability among pathologists using this methodology in grading. The objective of this study was to explore if newly available digital reading technologies can reduce inter-reader variability. IN THIS STUDY, WE CONSIDERED THREE DIFFERENT READING CONDITIONS (RCS) IN GRADING FL: (1) Conventional (glass-slide based) to establish the baseline, (2) digital whole slide viewing, (3) digital whole slide viewing with selected HPFs. Six board-certified pathologists from five different institutions read 17 FL slides in these three different RCs. Although there was relative poor consensus in conventional reading, with lack of consensus in 41.2% of cases, which was similar to previously reported studies; we found that digital reading with pre-selected fields improved the inter-reader agreement, with only 5.9% lacking consensus among pathologists. Digital whole slide RC resulted in the worst concordance among pathologists while digital whole slide reading selected HPFs improved the concordance. Further studies are underway to determine if this performance can be sustained with a larger dataset and our automated HPF and CB detection algorithms can be employed to further improve the concordance.

  7. Inter-reader variability in follicular lymphoma grading: Conventional and digital reading

    Directory of Open Access Journals (Sweden)

    Gerard Lozanski

    2013-01-01

    Full Text Available Context: Pathologists grade follicular lymphoma (FL cases by selecting 10, random high power fields (HPFs, counting the number of centroblasts (CBs in these HPFs under the microscope and then calculating the average CB count for the whole slide. Previous studies have demonstrated that there is high inter-reader variability among pathologists using this methodology in grading. Aims: The objective of this study was to explore if newly available digital reading technologies can reduce inter-reader variability. Settings and Design: In this study, we considered three different reading conditions (RCs in grading FL: (1 Conventional (glass-slide based to establish the baseline, (2 digital whole slide viewing, (3 digital whole slide viewing with selected HPFs. Six board-certified pathologists from five different institutions read 17 FL slides in these three different RCs. Results: Although there was relative poor consensus in conventional reading, with lack of consensus in 41.2% of cases, which was similar to previously reported studies; we found that digital reading with pre-selected fields improved the inter-reader agreement, with only 5.9% lacking consensus among pathologists. Conclusions: Digital whole slide RC resulted in the worst concordance among pathologists while digital whole slide reading selected HPFs improved the concordance. Further studies are underway to determine if this performance can be sustained with a larger dataset and our automated HPF and CB detection algorithms can be employed to further improve the concordance.

  8. Digital versus conventional panoramic radiography in predicting inferior alveolar nerve injury after mandibular third molar removal.

    Science.gov (United States)

    Szalma, József; Lempel, Edina; Jeges, Sára; Olasz, Lajos

    2012-03-01

    The aim of the study was to compare the accuracy of conventional and digital panoramic radiography (OPG) in relation to 4 specific high-risk signs (interruption of the superior cortical line, diversion, narrowing of the canal, and dark band of the root), which would indicate a close anatomic relationship between third molar roots and the inferior alveolar canal.Four hundred mandibular third molar surgical removals after conventional and 272 after digital radiographs were evaluated in the study. The association between postoperative inferior alveolar nerve (IAN) paresthesia and the presence of any preoperative high-risk signs in the OPG was investigated. Bivariate and multivariate logistic regression analyses were completed to compare the accuracy of conventional and digital radiographic techniques detecting high-risk signs predicting possible IAN paresthesia.Digital OPG results showed significantly higher sensitivity in diversion (P = 0.014) and narrowing (P paresthesia, whereas low positive predictive values indicate both imaging techniques as inadequate screening methods for predicting IAN paresthesia after mandibular third molar removal.

  9. Comparative Study of Communication Error between Conventional and Digital MCR Operators in NPPs

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Seung Geun; Seong, Poong Hyun [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of)

    2015-05-15

    In this regard, the appropriate communication is directly related to the efficient and safe system operation, and inappropriate communication is one of the main causes of the accidents in various industries since inappropriate communications can cause a lack of necessary information exchange between operators and lead to serious consequences in large process systems such as nuclear power plants. According to the study conducted by Y. Hirotsu in 2001, about 25 percents of human error caused incidents in NPPs were related to communication issues. Also, other studies were reported that 85 percents of human error caused incidents in aviation industry and 92 percents in railway industry were related to communication problems. Accordingly, the importance of the efforts for reducing inappropriate communications has been emphasized in order to enhance the safety of pre-described systems. As a result, the average ratio of inappropriate communication in digital MCRs was slightly higher than that in conventional MCRs when the average ratio of no communication in digital MCRs was much smaller than that in conventional MCRs. Regarding the average ratio of inappropriate communication, it can be inferred that operators are still more familiar to the conventional MCRs than digital MCRs. More case studies are required for more delicate comparison since there were only three examined cases for digital MCRs. However, similar result is expected because there are no differences in communication method, although there are many differences in the way of procedure proceeding.

  10. Radiopacity of restorative composites by conventional radiography and digital images with different resolutions

    Energy Technology Data Exchange (ETDEWEB)

    Dantas, Raquel Venancio; Samento, Hugo Ramalho [Graduate Program in Dentistry, Federal University of Pelotas, Pelotas (Brazil); Duarte, Rosangela Marques; Raso, Sonia Saeger Meireles Monte; De Andrade Ana Karina Maciel; Anjos-Pontual Maria Luiza Dos [Dept. of Operative Dentistry, Federal University of Paraiba, Pelotas (Brazil)

    2013-09-15

    This study was performed to evaluate and compare the radiopacity of dentin, enamel, and 8 restorative composites on conventional radiograph and digital images with different resolutions. Specimens were fabricated from 8 materials and human molars were longitudinally sectioned 1.0 mm thick to include both enamel and dentin. The specimens and tooth sections were imaged by conventional radiograph using 4 sized intraoral film and digital images were taken in high speed and high resolution modes using a phosphor storage plate. Densitometric evaluation of the enamel, dentin, restorative materials, a lead sheet, and an aluminum step wedge was performed on the radiographic images. For the evaluation, the Al equivalent (mm) for each material was calculated. The data were analyzed using one-way ANOVA and Tukey's test (p<0.05), considering the material factor and then the radiographic method factor, individually. The high speed mode allowed the highest radiopacity, while the high resolution mode generated the lowest values. Furthermore, the high resolution mode was the most efficient method for radiographic differentiation between restorative composites and dentin. The conventional radiograph was the most effective in enabling differentiation between enamel and composites. The high speed mode was the least effective in enabling radiographic differentiation between the dental tissues and restorative composites. The high speed mode of digital imaging was not effective for differentiation between enamel and composites. This made it less effective than the high resolution mode and conventional radiographs. All of the composites evaluated showed radiopacity values that fit the ISO 4049 recommendations.

  11. The reliability and reproducibility of cephalometric measurements: a comparison of conventional and digital methods

    Science.gov (United States)

    AlBarakati, SF; Kula, KS; Ghoneima, AA

    2012-01-01

    Objective The aim of this study was to assess the reliability and reproducibility of angular and linear measurements of conventional and digital cephalometric methods. Methods A total of 13 landmarks and 16 skeletal and dental parameters were defined and measured on pre-treatment cephalometric radiographs of 30 patients. The conventional and digital tracings and measurements were performed twice by the same examiner with a 6 week interval between measurements. The reliability within the method was determined using Pearson's correlation coefficient (r2). The reproducibility between methods was calculated by paired t-test. The level of statistical significance was set at p < 0.05. Results All measurements for each method were above 0.90 r2 (strong correlation) except maxillary length, which had a correlation of 0.82 for conventional tracing. Significant differences between the two methods were observed in most angular and linear measurements except for ANB angle (p = 0.5), angle of convexity (p = 0.09), anterior cranial base (p = 0.3) and the lower anterior facial height (p = 0.6). Conclusion In general, both methods of conventional and digital cephalometric analysis are highly reliable. Although the reproducibility of the two methods showed some statistically significant differences, most differences were not clinically significant. PMID:22184624

  12. Determination of fat and total protein content in milk using conventional digital imaging

    DEFF Research Database (Denmark)

    Kucheryavskiy, Sergey; Melenteva, Anastasiia; Bogomolov, Andrey

    2014-01-01

    The applicability of conventional digital imaging to quantitative determination of fat and total protein in cow’s milk, based on the phenomenon of light scatter, has been proved. A new algorithm for extracting features from digital images of milk samples has been developed. The algorithm takes...... with cross-validated R2=0.890 for fat content and R2=0.720 for protein content). The results have been compared with previously published Vis/SW-NIR spectroscopic study of similar samples....

  13. A comparison of digitally scanned radiographs with conventional film for the detection of small endodontic instruments.

    Science.gov (United States)

    Fuge, K N; Stuck, A M; Love, R M

    1998-03-01

    The use of computers in dentistry is becoming common as a practice tool for a diverse number of tasks, including the storage and enhancement of intra-oral radiographs. Several systems of digital radiography are available to produce a digital image including irradiation of a charged-couple device and scanning conventional radiographs. This study compared various digital images of scanned periapical radiographs with the original radiographs to determine whether the digitized images offered any advantage when viewing small files at the radiographic apex. Twenty extracted permanent molar teeth were prepared by gaining straight line access to the root canals and a ISO size 06 K-file was introduced into one of the canals until the tip was flush with the apical foramen. Using a standardized technique, radiographs were taken of the teeth using E-speed film. The radiographs were scanned and five digital images: original, enhanced, negative to positive conversion, zoom and zoom of negative to positive were produced. Three evaluators compared each of the images with the radiograph for clarity of the endodontic file in relation to the radiographic apex. Results were analysed using the Wilcoxon signed rank test and the Kappa (kappa) test was used to measure the level of agreement between the three evaluators. The results revealed that all the digital images produced by this scanner were inferior to the radiograph (P < 0.001) and that there was high agreement between evaluators.

  14. Dental anatomy grading: comparison between conventional visual and a novel digital assessment technique.

    Science.gov (United States)

    Kwon, So Ran; Restrepo-Kennedy, Natalia; Dawson, Deborah V; Hernandez, Marcela; Denehy, Gerald; Blanchette, Derek; Gratton, David G; Aquilino, Steven A; Armstrong, Steven R

    2014-12-01

    Conventional grading of dental students' projects in preclinical courses has mainly relied on visual evaluation by experienced instructors. The purpose of this study was to compare conventional visual grading in a dental anatomy course at one U.S. dental school to a novel digital assessment technique. A total of sixty samples comprised of two sets of faculty wax-ups (n=30), student wax-ups (n=15), and dentoform teeth of tooth #14 (n=15) were used for this study. Two additional faculty members visually graded the samples according to a checklist and then repeated the grading after one week. The sample wax-up with the highest score based on the visual grading was selected as the master model for the digital grading, which was also performed twice with an interim period of one week. Descriptive statistics and signed rank tests for systematic bias were used for intra- and interrater comparisons. The intraclass correlation (ICC) was used as a measure of intra- and interrater reliability. None of the faculty members achieved the minimum acceptable intrarater agreement of 0.8. Interrater agreement was substantially less than intrarater agreement for the visual grading, whereas all measures of intrarater agreement were greater than 0.9 and considered excellent for the digital assessment technique. These results suggest that visual grading is limited by modest intrarater reliability and low interrater agreement. Digital grading is a promising evaluation method showing excellent intrarater reliability and correlation. Correlation for visual and digital grading was consistently modest, partly supporting the potential use of digital technology in dental anatomy grading.

  15. Reproducibility between conventional and digital periapical radiography for bone height measurement

    Directory of Open Access Journals (Sweden)

    Miguel Simancas-Pallares

    2015-10-01

    Full Text Available Background. Several diagnostic aids are available for bone height measurement. Digital and conventional radiographs are the two ones most used in Dentistry. Few studies accounting for accuracy and precision have been conducted to compare these methods. Objective. The aim of this study was to estimate reproducibility between conventional and digital periapical radiography in bone height measurement in patients with chronic periodontitis. Methods. a consistency diagnostic test study was performed. 136 patients with chronic periodontitis were included, selecting the worst prognosis teeth and two radiographs -conventional and digital- were taken for each one. Two experienced and blinded examiners performed radiographic measurements. Reproducibility was obtained through Lin's concordance correlation coefficient by using the statistical package STATA™ for Windows. Results. Average age was 38.8 (SD: 9.9 and 61.6 % were female patients. 125 pairs of matched radiographs for 1000 measurements were evaluated. Overall reproducibility between the methods for mesial and distal measurements were 0.62 (95% CI: 0.55-0.70 and 0.64 (95% CI: 0.57-0.71 respectively. Conclusions. Reproducibility between methods was considered poor, including subgroup analysis, therefore, reproducibility between methods is minimal. Usage of these methods in periodontics should be made implementing the whole knowledge of the technical features and the advantages of these systems.

  16. Solum depth spatial prediction comparing conventional with knowledge-based digital soil mapping approaches

    Directory of Open Access Journals (Sweden)

    Michele Duarte de Menezes

    2014-08-01

    Full Text Available Solum depth and its spatial distribution play an important role in different types of environmental studies. Several approaches have been used for fitting quantitative relationships between soil properties and their environment in order to predict them spatially. This work aimed to present the steps required for solum depth spatial prediction from knowledge-based digital soil mapping, comparing the prediction to the conventional soil mapping approach through field validation, in a watershed located at Mantiqueira Range region, in the state of Minas Gerais, Brazil. Conventional soil mapping had aerial photo-interpretation as a basis. The knowledge-based digital soil mapping applied fuzzy logic and similarity vectors in an expert system. The knowledge-based digital soil mapping approach showed the advantages over the conventional soil mapping approach by applying the field expert-knowledge in order to enhance the quality of final results, predicting solum depth with suited accuracy in a continuous way, making the soil-landscape relationship explicit.

  17. Contexts for Column Addition and Subtraction

    Science.gov (United States)

    Lopez Fernandez, Jorge M.; Velazquez Estrella, Aileen

    2011-01-01

    In this article, the authors discuss their approach to column addition and subtraction algorithms. Adapting an original idea of Paul Cobb and Erna Yackel's from "A Contextual Investigation of Three-Digit Addition and Subtraction" related to packing and unpacking candy in a candy factory, the authors provided an analogous context by…

  18. Contexts for Column Addition and Subtraction

    Science.gov (United States)

    Lopez Fernandez, Jorge M.; Velazquez Estrella, Aileen

    2011-01-01

    In this article, the authors discuss their approach to column addition and subtraction algorithms. Adapting an original idea of Paul Cobb and Erna Yackel's from "A Contextual Investigation of Three-Digit Addition and Subtraction" related to packing and unpacking candy in a candy factory, the authors provided an analogous context by…

  19. NOTE: Suppression of high-density artefacts in x-ray CT images using temporal digital subtraction with application to cryotherapy

    Science.gov (United States)

    Baissalov, R.; Sandison, G. A.; Donnelly, B. J.; Saliken, J. C.; McKinnon, J. G.; Muldrew, K.; Rewcastle, J. C.

    2000-05-01

    Image guidance in cryotherapy is usually performed using ultrasound. Although not currently in routine clinical use, x-ray CT imaging is an alternative means of guidance that can display the full 3D structure of the iceball, including frozen and unfrozen regions. However, the quality of x-ray CT images is compromised by the presence of high-density streak artefacts. To suppress these artefacts we applied temporal digital subtraction (TDS). This TDS method has the added advantage of improving the grey-scale contrast between frozen and unfrozen tissue in the CT images. Two sets of CT images were taken of a phantom material, cryoprobes and a urethral warmer (UW) before and during the cryoprobe freeze cycle. The high-density artefacts persisted in both image sets. TDS was performed on these two image sets using the corresponding mask image of unfrozen material and the same geometrical configuration of the cryoprobes and the UW. The resultant difference image had a significantly reduced artefact content. Thus TDS can be used to significantly suppress or eliminate high-density CT streak artefacts without reducing the metallic content of the cryoprobes. In vivo study needs to be conducted to establish the utility of this TDS procedure for CT assisted prostate or liver cryotherapy. Applying TDS in x-ray CT guided cryotherapy will facilitate estimation of the number and location of all frozen and unfrozen regions, potentially making cryotherapy safer and less operator dependent.

  20. Non-contrast-enhanced MR angiography in the diagnosis of Budd-Chiari syndrome (BCS) compared with digital subtraction angiography (DSA): Preliminary results.

    Science.gov (United States)

    Yang, Chun; Li, Ceng; Zeng, Mengsu; Lu, Xin; Li, Jingjing; Wang, Jiali; Sami, Muhammad Umair; Xu, Kai

    2017-02-01

    Non-CE MRA techniques (true steady-state free-precession, SSFP) have been used effectively for the selective visualization of the portal venous system and inferior vena cava. Budd-Chiari Syndrome (BCS) encompasses a number of conditions that cause the obstruction of the hepatic outflow tract from the small hepatic veins to the junction of the inferior vena cava (IVC) and right atrium. The purpose of this study was to diagnose BCS with IVC obstruction using respiratory triggered three-dimensional (3D) true SSFP with T-SLIP and compare to digital subtraction angiography (DSA). The image acquisition of 3D true SSFP scans was successfully performed in 108 patients (≧2 score). The mean and SDs of the relative SNR and CNR were 55.96±2.32 and 30.72±1.56, respectively. Intergroup agreement for the detection of the 4 types (membranous obstruction, segmental occlusion, and membranous obstruction with a hole and segmental stenosis) of BCS with IVC obstruction was excellent between the Time-SLIP and the DSA. In conclusion, Time-SLIP for the detection of IVC obstruction BCS does not require the use of contrast. This procedure can achieve a high success rate, high accuracy rate and fine image quality for the diagnosis of IVC obstruction BCS. Copyright © 2016 Elsevier Inc. All rights reserved.

  1. Usefulness of magnetic resonance imaging (MRI) in the detection of the lesions of gestational trophoblastic disease; Comparison with computed tomography and digital subtraction angiography

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    Takeuchi, Satoshi; Akahori, Taiichiro; Mochizuki, Matsuto; Kono, Michio (Kobe Univ. (Japan). School of Medicine)

    1992-02-01

    Twenty patients with gestational trophoblastic disease (GTN) were examined by magnetic resonance imaging (MRI), computed tomography (CT) and digital subtraction angiography (DSA), to evaluate their usefulness in the diagnosis of the disease. The lesions of hydatidiform mole were mainly composed of molar vesicles, dilated vessels and hemorrhage which were depicted as small round high intensity lesions on the T2-weighted images and as tree-like low intensity lesions and high or low intensity lesions of various shapes in the T1-, T2-weighted images. These MRI findings closely corresponded to the histopathological findings. On the other hand, CT findings obtained with hydatidiform mole were characterized by filling defects or a small round low density area on contrast enhanced images. The detection ratio for intramural lesions of invasive mole and choriocarcinoma by MRI was 83% (5/6), while that by CT was 50% (3/6). The obliteration of the junctional zone and interruption of the myometrium observed in MRI were significant signs suggesting intramural invasion of the disease. In fact, these signs in MRI were observed in all of the six cases of invasive mole or choriocarcinoma examined. In conclusion, MRI is a powerful means for the determining the intramural invasive mole and choriocarcinoma. Thus more accurate diagnosis of GTN will be obtained with the combined use of MRI and DSA. (author).

  2. Flow modification in canine intracranial aneurysm model by an asymmetric stent: studies using digital subtraction angiography (DSA) and image-based computational fluid dynamics (CFD) analyses

    Science.gov (United States)

    Hoi, Yiemeng; Ionita, Ciprian N.; Tranquebar, Rekha V.; Hoffmann, Kenneth R.; Woodward, Scott H.; Taulbee, Dale B.; Meng, Hui; Rudin, Stephen

    2006-03-01

    An asymmetric stent with low porosity patch across the intracranial aneurysm neck and high porosity elsewhere is designed to modify the flow to result in thrombogenesis and occlusion of the aneurysm and yet to reduce the possibility of also occluding adjacent perforator vessels. The purposes of this study are to evaluate the flow field induced by an asymmetric stent using both numerical and digital subtraction angiography (DSA) methods and to quantify the flow dynamics of an asymmetric stent in an in vivo aneurysm model. We created a vein-pouch aneurysm model on the canine carotid artery. An asymmetric stent was implanted at the aneurysm, with 25% porosity across the aneurysm neck and 80% porosity elsewhere. The aneurysm geometry, before and after stent implantation, was acquired using cone beam CT and reconstructed for computational fluid dynamics (CFD) analysis. Both steady-state and pulsatile flow conditions using the measured waveforms from the aneurysm model were studied. To reduce computational costs, we modeled the asymmetric stent effect by specifying a pressure drop over the layer across the aneurysm orifice where the low porosity patch was located. From the CFD results, we found the asymmetric stent reduced the inflow into the aneurysm by 51%, and appeared to create a stasis-like environment which favors thrombus formation. The DSA sequences also showed substantial flow reduction into the aneurysm. Asymmetric stents may be a viable image guided intervention for treating intracranial aneurysms with desired flow modification features.

  3. Comparison between detailed digital and conventional soil maps of an area with complex geology

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    Osmar Bazaglia Filho

    2013-10-01

    Full Text Available Since different pedologists will draw different soil maps of a same area, it is important to compare the differences between mapping by specialists and mapping techniques, as for example currently intensively discussed Digital Soil Mapping. Four detailed soil maps (scale 1:10.000 of a 182-ha sugarcane farm in the county of Rafard, São Paulo State, Brazil, were compared. The area has a large variation of soil formation factors. The maps were drawn independently by four soil scientists and compared with a fifth map obtained by a digital soil mapping technique. All pedologists were given the same set of information. As many field expeditions and soil pits as required by each surveyor were provided to define the mapping units (MUs. For the Digital Soil Map (DSM, spectral data were extracted from Landsat 5 Thematic Mapper (TM imagery as well as six terrain attributes from the topographic map of the area. These data were summarized by principal component analysis to generate the map designs of groups through Fuzzy K-means clustering. Field observations were made to identify the soils in the MUs and classify them according to the Brazilian Soil Classification System (BSCS. To compare the conventional and digital (DSM soil maps, they were crossed pairwise to generate confusion matrices that were mapped. The categorical analysis at each classification level of the BSCS showed that the agreement between the maps decreased towards the lower levels of classification and the great influence of the surveyor on both the mapping and definition of MUs in the soil map. The average correspondence between the conventional and DSM maps was similar. Therefore, the method used to obtain the DSM yielded similar results to those obtained by the conventional technique, while providing additional information about the landscape of each soil, useful for applications in future surveys of similar areas.

  4. Effect of prosthodontic planning on lateral occlusion scheme: a comparison between conventional and digital planning

    Directory of Open Access Journals (Sweden)

    Jaafar ABDUO

    2015-04-01

    Full Text Available Recently, digital wax-up is proposed as a tool to aid prosthodontic planning. However, there are no data about the effect of prosthodontic planning on lateral occlusion scheme. Objective : This study aims to evaluate the impact of conventional and digital prosthodontic planning on lateral occlusion scheme. Material and Methods : Dental models of 10 patients were collected. All models had Angle Class I occlusion and were undergoing prosthodontic treatment that would influence the lateral occlusion scheme. Each set of models had received both conventional wax-up and digital wax-up. In relation to the lateral occlusion scheme, the following variables were evaluated: the prevalence of the different lateral occlusion scheme, number of contacting teeth and percentage of each contacting tooth. Four excursive positions on the working side were included: 0.5, 1.0, 2.0 and 3.0 mm from the maximal intercuspation position. Results : The lateral occlusion scheme of the two wax-up models was subjected to alterations following excursion. There was a tendency for the prevalence of canine-guided occlusion to increase and for the prevalence of group function occlusion to decrease with increasing excursion. The number of contacting teeth was decreasing with the increasing magnitude of excursion. For the 0.5 mm and 1.0 mm positions, the two wax-ups had significantly greater contacts than the pre-treatment models, while at the 2.0 mm and 3.0 mm positions, all the models were similar. For all models, canines were the most commonly contacting teeth, followed by the teeth adjacent to them. No difference was observed between the two wax-ups in relation to the number of contacting teeth. Conclusion : Although the prosthodontic planning had influenced the pattern of the lateral occlusion scheme and contacts, there was no difference between the conventional and digital prosthodontic planning.

  5. Computed tomography angiography in the evaluation of carotid artery bifurcation stenosis: comparison with intraarterial digital subtraction angiography; Angio-TC en la evaluacion de estenosis de la bifurcacion arterial carotidea: comparacion con arteriografia por sustraccion digital intraarterial

    Energy Technology Data Exchange (ETDEWEB)

    Santos, A. L.; Ramos, M.; Delgado, F.; Cano, A.; Bravo, F. [Hospital Universitario Reina Sofia. Cordoba (Spain)

    2001-07-01

    To determine the value of computed tomography (CT) angiography in grading cervical carotid artery stenosis, comparing it with that of intraarterial digital subtraction angiography (IADSA), and to demonstrate the utility of CT angiography, under certain circumstances, as an alternative to carotid angiography in the diagnosis of arterial disease. Of the 428 patients who underwent CT andiography of the supraaortic trunk in our hospital between lily 1998 and September 2000, the results in the first 55 in whom Id's was performed concomitantly were reviewed, and the findings with two techniques compared. In the discrimination of stenosis >70%, CT angiography showed a sensitivity of 92%, a specificity of 98% and an overall precision of 95% with respect to IADSA. The good correlation of the grading of carotid artery stenosis by CT angiography with that of IADSA suggests its high diagnostic reliability. (Author) 38 refs.

  6. TU-CD-207-03: Time Evolution of Texture Parameters of Subtracted Images Obtained by Contrast-Enhanced Digital Mammography (CEDM)

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    Mateos, M-J; Brandan, M-E [Instituto de Fisica, Universidad Nacional Autonom de Mexico, Mexico, Distrito Federal (Mexico); Gastelum, A; Marquez, J [Centro de Ciencias Aplicadas y Desarrollo Tecnologico Universidad Nacional Autonoma de Mexico, Mexico, Distrito Federal (Mexico)

    2015-06-15

    Purpose: To evaluate the time evolution of texture parameters, based on the gray level co-occurrence matrix (GLCM), in subtracted images of 17 patients (10 malignant and 7 benign) subjected to contrast-enhanced digital mammography (CEDM). The goal is to determine the sensitivity of texture to iodine uptake at the lesion, and its correlation (or lack of) with mean-pixel-value (MPV). Methods: Acquisition of clinical images followed a single-energy CEDM protocol using Rh/Rh/48 kV plus external 0.5 cm Al from a Senographe DS unit. Prior to the iodine-based contrast medium (CM) administration a mask image was acquired; four CM images were obtained 1, 2, 3, and 5 minutes after CM injection. Temporal series were obtained by logarithmic subtraction of registered CM minus mask images.Regions of interest (ROI) for the lesion were drawn by a radiologist and the texture was analyzed. GLCM was evaluated at a 3 pixel distance, 0° angle, and 64 gray-levels. Pixels identified as registration errors were excluded from the computation. 17 texture parameters were chosen, classified according to similarity into 7 groups, and analyzed. Results: In all cases the texture parameters within a group have similar dynamic behavior. Two texture groups (associated to cluster and sum mean) show a strong correlation with MPV; their average correlation coefficient (ACC) is r{sup 2}=0.90. Other two groups (contrast, homogeneity) remain constant with time, that is, a low-sensitivity to CM uptake. Three groups (regularity, lacunarity and diagonal moment) are sensitive to CM uptake but less correlated with MPV; their ACC is r{sup 2}=0.78. Conclusion: This analysis has shown that, at least groups associated to regularity, lacunarity and diagonal moment offer dynamical information additional to the mean pixel value due to the presence of CM at the lesion. The next step will be the analysis in terms of the lesion pathology. Authors thank PAPIIT-IN105813 for support. Consejo Nacional de Ciencia Y

  7. Comparison of conventional study model measurements and 3D digital study model measurements from laser scanned dental impressions

    Science.gov (United States)

    Nugrahani, F.; Jazaldi, F.; Noerhadi, N. A. I.

    2017-08-01

    The field of orthodontics is always evolving,and this includes the use of innovative technology. One type of orthodontic technology is the development of three-dimensional (3D) digital study models that replace conventional study models made by stone. This study aims to compare the mesio-distal teeth width, intercanine width, and intermolar width measurements between a 3D digital study model and a conventional study model. Twelve sets of upper arch dental impressions were taken from subjects with non-crowding teeth. The impressions were taken twice, once with alginate and once with polivinylsiloxane. The alginate impressions used in the conventional study model and the polivinylsiloxane impressions were scanned to obtain the 3D digital study model. Scanning was performed using a laser triangulation scanner device assembled by the School of Electrical Engineering and Informatics at the Institut Teknologi Bandung and David Laser Scan software. For the conventional model, themesio-distal width, intercanine width, and intermolar width were measured using digital calipers; in the 3D digital study model they were measured using software. There were no significant differences between the mesio-distal width, intercanine width, and intermolar width measurments between the conventional and 3D digital study models (p>0.05). Thus, measurements using 3D digital study models are as accurate as those obtained from conventional study models

  8. Effect of changing the kilovoltage peak on radiographic caries assessment in digital and conventional radiography

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    Zayet, Mohamed Khalifa; Helaly, Yara Rabee; Eiid, Salma Belal [Dept. of Oral Radiology, Faculty of Oral and Dental Medicine, Cairo University, Cairo (Egypt)

    2014-09-15

    This study aimed to investigate the effect of changing the kilovoltage peak (kVp) on the radiographic assessment of dental caries. Seventy-five extracted posterior teeth with proximal caries or apparently sound proximal surfaces were radiographed with conventional E-speed films and a photostimulable phosphor system using 60 kVp and 70 kVp for the caries assessment. The images were evaluated by three oral radiologists and compared with the results of the stereomicroscope analysis. No statistically significant difference was found between 60 kVp and 70 kVp for the caries detection, determination of caries extension into dentin, and caries severity in either the conventional or the digital images. Good to very good inter-observer and intra-observer agreements were found for both kilovoltage values on the conventional and digital images. Changing the kilovoltage between 60 kVp and 70 kVp had no obvious effect on the detection of proximal caries or determination of its extension or severity.

  9. Some aspects on radiation protection in conventional and digital radiology in Romania.

    Science.gov (United States)

    Milu, Constantin; Dumitrescu, Alina

    2008-01-01

    Since 1965, medical radiation exposure in the population of Romania has been evaluated by the Network of Radiation Hygiene Laboratories of the Ministry of Public Health, including 23 laboratories throughout the whole country; the network is co-ordinated by the Institute of Public Health Bucharest. In Romania, for a population of 22.5 million inhabitants, 465 X-ray examinations were reported during the last survey, the most frequent being chest examination. There was no specific reference to digital radiology. Digital radiology has been introduced only recently in Romania, and only some rough data on the situation can be presented. Siemens AG is now present in Romania with 23 installations, type SIEREGRAPH CF and AXIOM ICONOS. A digital image intensifier technique is used only for fluoroscopy, and radiography is performed using a conventional film/screen combination. The company Philips has nine installations for angiography, model INTEGRIS, and uses a computed radiography technique. Several direct digital radiography MULTISYSTEM SWISSRAY installations (about 40 units) are also available for adult and paediatric examinations. The Council Directive 97/43/EURATOM on health protection of individuals against dangers of ionising radiation in relation to medical exposure was fully transformed into Romanian legislation in 2002.

  10. Comparing the Ability of Conventional and Digital Soil Maps to Explain Soil Variability using Diversity Indices

    Directory of Open Access Journals (Sweden)

    zohreh mosleh

    2017-06-01

    Full Text Available Introduction: Effective and sustainable soil management requires knowledge about the spatial patterns of soil variation and soil surveys are important and useful sources of data that can be used. Prior knowledge about the spatial distribution of the soils is the first essential step for this aim but this requires the collection of large amounts of soil information. However, the conventional soil surveys are usually not useful for providing quantitative information about the spatial distribution of soil properties that are used in many environmental studies. Recently, by the rapid development of the computers and technology together with the availability of new types of remote sensing data and digital elevation models (DEMs, digital and quantitative approaches have been developed. These new techniques relies on finding the relationships between soil properties or classes and the auxiliary information that explain the soil forming factors or processes and finally predict soil patterns on the landscape. Different types of the machine learning approaches have been applied for digital soil mapping of soil classes, such as the logistic and multinomial logistic regressions, neural networks and classification trees. In reality, soils are physical outcomes of the interactions happening among the geology, climate, hydrology and geomorphic processes. Diversity is a way of measuring soil variation. Ibanez (9 first introduced ecological diversity indices as measures of diversity. Application of the diversity indices in soil science have considerably increased in recent years. Taxonomic diversity has been evaluated in the most previous researches whereas comparing the ability of different soil mapping approaches based on these indices was rarely considered. Therefore, the main objective of this study was to compare the ability of the conventional and digital soil maps to explain the soil variability using diversity indices in the Shahrekord plain of

  11. Color-coded digital subtraction angiography in the management of a rare case of middle cerebral artery pure arterial malformation. A technical and case report.

    Science.gov (United States)

    Feliciano, Caleb E; Pamias-Portalatin, Eva; Mendoza-Torres, Jorge; Effio, Euclides; Moran, Yadira; Rodriguez-Mercado, Rafael

    2014-12-01

    The advent of flow dynamics and the recent availability of perfusion analysis software have provided new diagnostic tools and management possibilities for cerebrovascular patients. To this end, we provide an example of the use of color-coded angiography and its application in a rare case of a patient with a pure middle cerebral artery (MCA) malformation. A 42-year-old male chronic smoker was evaluated in the emergency room due to sudden onset of severe headache, nausea, vomiting and left-sided weakness. Head computed tomography revealed a right basal ganglia hemorrhage. Cerebral digital subtraction angiography (DSA) showed a right middle cerebral artery malformation consisting of convoluted and ectatic collateral vessels supplying the distal middle cerebral artery territory-M1 proximally occluded. An associated medial lenticulostriate artery aneurysm was found. Brain single-photon emission computed tomography with and without acetazolamide failed to show problems in vascular reserve that would indicate the need for flow augmentation. Twelve months after discharge, the patient recovered from the left-sided weakness and did not present any similar events. A follow-up DSA and perfusion study using color-coded perfusion analysis showed perforator aneurysm resolution and adequate, albeit delayed perfusion in the involved vascular territory. We propose a combined congenital and acquired mechanism involving M1 occlusion with secondary dysplastic changes in collateral supply to the distal MCA territory. Angiographic and cerebral perfusion work-up was used to exclude the need for flow augmentation. Nevertheless, the natural course of this lesion remains unclear and long-term follow-up is warranted.

  12. Gadofosveset-enhanced MR angiography of carotid arteries: does steady-state imaging improve accuracy of first-pass imaging? Comparison with selective digital subtraction angiography.

    Science.gov (United States)

    Anzidei, Michele; Napoli, Alessandro; Marincola, Beatrice Cavallo; Nofroni, Italo; Geiger, Daniel; Zaccagna, Fulvio; Catalano, Carlo; Passariello, Roberto

    2009-05-01

    To evaluate the diagnostic accuracy of gadofosveset-enhanced magnetic resonance (MR) angiography in the assessment of carotid artery stenosis, with digital subtraction angiography (DSA) as the reference standard, and to determine the value of reading first-pass, steady-state, and "combined" (first-pass plus steady-state) MR angiograms. This study was approved by the local ethics committee, and all subjects gave written informed consent. MR angiography and DSA were performed in 84 patients (56 men, 28 women; age range, 61-76 years) with carotid artery stenosis at Doppler ultrasonography. Three readers reviewed the first-pass, steady-state, and combined MR data sets, and one independent observer evaluated the DSA images to assess stenosis degree, plaque morphology and ulceration, stenosis length, and tandem lesions. Interobserver agreement regarding MR angiographic findings was analyzed by using intraclass correlation and Cohen kappa coefficients. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated by using the McNemar test to determine possible significant differences (P < .05). Interobserver agreement regarding all MR angiogram readings was substantial. For grading stenosis, sensitivity, specificity, PPV, and NPV were, respectively, 90%, 92%, 91%, and 91% for first-pass imaging; 95% each for steady-state imaging; and 96%, 99%, 99%, and 97% for combined imaging. For evaluation of plaque morphology, respective values were 84%, 86%, 88%, and 82% for first-pass imaging; 98%, 97%, 98%, and 97% for steady-state imaging; and 98%, 100%, 100%, and 97% for combined imaging. Differences between the first-pass, steady-state, and combined image readings for assessment of stenosis degree and plaque morphology were significant (P < .001). Gadofosveset-enhanced MR angiography is a promising technique for imaging carotid artery stenosis. Steady-state image reading is superior to first-pass image reading, but the combined

  13. Three-dimensional time-of-flight MR angiography for evaluation of intracranial aneurysms after endosaccular packing with Guglielmi detachable coils: comparison with 3D digital subtraction angiography

    Energy Technology Data Exchange (ETDEWEB)

    Okahara, Mika [Department of Radiology, Nagatomi Neurosurgical Hospital, Oita (Japan); Department of Radiology, Oita University Faculty of Medicine, 1-1 Hasama-machi, 879-5503, Oita (Japan); Kiyosue, Hiro; Mori, Hiromu [Department of Radiology, Oita University Faculty of Medicine, 1-1 Hasama-machi, 879-5503, Oita (Japan); Hori, Yuzo [Department of Radiology, Nagatomi Neurosurgical Hospital, Oita (Japan); Yamashita, Masanori; Nagatomi, Hirofumi [Department of Neurosurgery, Nagatomi Neurosurgical Hospital, Oita (Japan)

    2004-07-01

    The sensitivities and specificities of three-dimensional time-of-flight MR angiography (3D-TOF MRA) and 3D digital subtraction angiography (3D-DSA) were compared for evaluation of cerebral aneurysms after endosaccular packing with Guglielmi detachable coils (GDCs). Thirty-three patients with 33 aneurysms were included in this prospective study. 3D-TOF MRA and 3D-DSA were performed in the same week on all patients. Maximal intensity projection (MIP) and 3D reconstructed MRA images were compared with 3D-DSA images. The diameters of residual/recurrent aneurysms detected on 3D-DSA were calculated on a workstation. In 3 (9%) of 33 aneurysms, 3D-TOF MRA did not provide reliable information due to significant susceptibility artifacts on MRA. The sensitivity and specificity rates of MRA were 72.7 and 90.9%, respectively, for the diagnosis of residual/recurrent aneurysm. The diameters of residual/recurrent aneurysms that could not be detected by MRA were significantly smaller than those of detected aneurysms (mean 1.1 vs mean 2.3 mm). In one aneurysm of the anterior communicating artery (ACoA), the relationship between the residual aneurysm and the ACoA was more evident on MRA than DSA images. MRA can detect the recurrent/residual lumen of aneurysms treated with GDCs of up to at least 1.8 mm in diameter. 3D-TOF MRA is useful for follow-up of intracranial aneurysms treated with GDCs, and could partly replace DSA. (orig.)

  14. Time-of-flight MR angiography at 3 T versus digital subtraction angiography in the imaging follow-up of 51 intracranial aneurysms treated with coils

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    Ferre, Jean-Christophe [Department of Neuroradiology, Hopital Pontchaillou, University Hospital Rennes, 2 rue Henri Le Guilloux, 35000 Rennes (France)], E-mail: jean-christophe.ferre@chu-rennes.fr; Carsin-Nicol, Beatrice [Department of Neuroradiology, Hopital Pontchaillou, University Hospital Rennes, 2 rue Henri Le Guilloux, 35000 Rennes (France); Morandi, Xavier [Department of Neurosurgery, Hopital Pontchaillou, University Hospital Rennes, 2 rue Henri Le Guilloux, 35000 Rennes (France); Carsin, Michel [Department of Neuroradiology, Hopital Pontchaillou, University Hospital Rennes, 2 rue Henri Le Guilloux, 35000 Rennes (France); Kersaint-Gilly, Axel de [Department of Neuroradiology, Hopital Laennec, University Hospital Nantes, Boulevard Jacques Monod, 44800 Saint-Herblain (France); Gauvrit, Jean-Yves [Department of Neuroradiology, Hopital Pontchaillou, University Hospital Rennes, 2 rue Henri Le Guilloux, 35000 Rennes (France); Desal, Hubert-Armand [Department of Neuroradiology, Hopital Laennec, University Hospital Nantes, Boulevard Jacques Monod, 44800 Saint-Herblain (France)

    2009-12-15

    Objective: To compare 3D time-of-flight MR angiography (TOF-MRA) at 3 Tesla (3 T) with digital subtraction angiography (DSA) for the evaluation of intracranial aneurysm occlusion after endovascular coiling. Methods: In a prospective study, 51 consecutive patients (25 females, 26 males; median age, 51 years) with 51 saccular aneurysms treated with endovascular coiling underwent simultaneous DSA and 3 T TOF-MRA at follow-up. DSA and TOF-MRA images were analyzed independently by two senior neuroradiologists. Findings were assigned to 1 of 3 categories in the Raymond classification: complete obliteration, residual neck or residual aneurysm. Agreement between observers and techniques was evaluated using {kappa} statistics. Results: DSA images were not interpretable for one patient. Interobserver agreement was determined as excellent for DSA ({kappa} = 0.86) and TOF-MRA ({kappa} = 0.80). After reaching a consensus, DSA follow-up showed 26 (51%) complete obliterations, 20 (39%) residual necks and 4 (8%) residual aneurysms. TOF-MRA showed 23 (45%) complete obliterations, 22 (43%) residual necks and 6 (12%) residual aneurysms. Comparison between TOF-MRA and DSA showed excellent agreement between the techniques ({kappa} = 0.86). In the four cases that were misclassified, TOF-MRA findings were assigned to a higher class than for DSA. Conclusion: TOF-MRA at 3 T is at least as efficient as DSA for the evaluation of intracranial aneurysm occlusion after endovascular treatment with detachable coils. We suggest that TOF-MRA at 3 T might be used as the primary method for imaging follow-up of coiled intracranial aneurysms.

  15. Contrast-enhanced angiographic computed tomography for detection of aneurysm remnants after clipping: a comparison with digital subtraction angiography in 112 clipped aneurysms.

    Science.gov (United States)

    Gölitz, Philipp; Struffert, Tobias; Ganslandt, Oliver; Lang, Stefan; Knossalla, Frauke; Doerfler, Arnd

    2014-06-01

    For preclusion of remnants after aneurysm clipping, a reliable, noninvasive imaging technique is desirable. To evaluate the reliability of optimized angiographic computed tomography with intravenous contrast agent injection (ivACT) in detecting remnants after aneurysmal clipping compared with digital subtraction angiography (DSA), the gold standard. We included 84 patients with 112 clipped cerebral aneurysms of the anterior circulation. For treatment, 116 clips of cobalt and 57 clips of titanium alloy were used. In each patient, we performed an ivACT with dual rotational acquisition and a DSA. Data from ivACT were postprocessed with a dual-volume technique with newly implemented reconstructions modes. Aneurysm remnants were measured, classified, and correlated with DSA by 2 raters. In total, 12 remnants were revealed by DSA, meaning a prevalence of 11%. IvACT demonstrated a sensitivity of 75% to 92% and a specificity of 99% in detecting remnants up to a minimal size of 0.7 × 0.3 mm. Classification of remnants by ivACT was identical to that by DSA, and assessment of size showed a significant correlation with DSA (P < .001). No significant differences between cobalt and titanium alloy were revealed concerning artifacts. Optimized ivACT with enhanced postprocessing demonstrated high sensitivity and specificity in detecting remnants after aneurysm clipping in the anterior circulation. Classification and assessment of remnant size and detection of relevant parent artery stenosis showed high accuracy of ivACT compared with DSA. Our results indicate that ivACT might become a noninvasive alternative to DSA for postsurgical control.

  16. Non-enhanced, ECG-gated MR angiography of the pedal vasculature: comparison with contrast-enhanced MR angiography and digital subtraction angiography in peripheral arterial occlusive disease.

    Science.gov (United States)

    Schubert, Tilman; Takes, Martin; Aschwanden, Markus; Klarhoefer, Markus; Haas, Tanja; Jacob, Augustinus L; Liu, David; Gutzeit, Andreas; Kos, Sebastian

    2016-08-01

    This study was conducted in order to compare a high resolution, non-contrast-enhanced MRA (NATIVE SPACE, NE-MRA) of the pedal vasculature with contrast-enhanced MRA (CE-MRA) and digital subtraction angiography (DSA) in patients with peripheral arterial occlusive disease (PAOD). The prospective study consists of 20 PAOD patients. All patients underwent percutaneous transluminal angioplasty or stenting and received MR angiographies the following day. With CE-MRA, 75.7 % of vessel segments showed good, 16.4 % suboptimal and 7.9 % not usable image quality. With NE-MRA, 64.6 % showed good, 18.6 % suboptimal and 16.8 % not usable image quality. CE-MRA showed a sensitivity and negative predictive value of 90 %/95 % regarding significant stenosis (greater than 50 %), and specificity and positive predictive value were 88 %/77 %. Accordingly, sensitivity and negative predictive value for the NE-MRA were 96 %/97 % and specificity and positive predictive value were 80 %/69 % for stenoses greater than 50 %. The applied NE-MRA technique achieves high diagnostic accuracy even in very small distal arteries of the foot. However, the rate of non-diagnostic vessel segments is considerably higher for NE-MRA than for CE-MRA. NE-MRA is a valuable alternative to CE-MRA in selected patients. • Comparison of non-enhanced MRA with contrast-enhanced MRA and DSA as gold standard. • High resolution MRA at 3 T for the depiction of small pedal vessels. • Evaluation of high resolution non-enhanced MRA in PAOD patients.

  17. A prospective feasibility study of duplex ultrasound arterial mapping, digital-subtraction angiography, and magnetic resonance angiography in management of critical lower limb ischemia by endovascular revascularization.

    Science.gov (United States)

    Lowery, A J; Hynes, N; Manning, B J; Mahendran, M; Tawfik, S; Sultan, S

    2007-07-01

    Duplex ultrasound arterial mapping (DUAM) allows precise evaluation of peripheral vascular disease (PVD). However, magnetic resonance angiography (MRA) and digital-subtraction angiography (DSA) are the diagnostic tools used most frequently prior to intervention. Our aim was to compare clinical pragmatism, hemodynamic outcomes, and cost-effectiveness when using DUAM alone compared to DSA or MRA as preoperative assessment tools for endovascular revascularization (EvR) in critical lower limb ischemia (CLI). From 2002 through 2005, 465 patients were referred with PVD. Of these, 199 had CLI and 137 required EvR. Preoperative diagnostic evaluation included DUAM (n = 41), DSA (n = 50), or MRA (n = 46). EvR was aortoiliac in 27% of cases and infrainguinal in 73%. Patients were assessed at day 1, 6 weeks, 3 months, and 6 months. Composite end points were relief of rest pain, ulcer/gangrene healing, and increase in perfusion pressure, as measured by ankle-brachial index (ABI) and digital pressures. Patency by DUAM, limb salvage, morbidity, mortality, length of stay, and cost-effectiveness were compared between groups using nonparametric t-test, analysis of variance, and Kaplan-Meier analysis. The three groups were comparable in terms of age, sex, comorbidity, and Society for Vascular Surgery/International Society of Cardiovascular Surgery clinical classification. Six-month mean improvement in ABI in the DUAM group was comparable to that in the DSA group (P = 0.25) and significantly better than that in the MRA group (P < 0.05). Six-month patency rates for the DUAM group were comparable to those in the DSA group (P = 0.68, relative risk [RR] = 0.74, 95% confidence interval [CI] 0.18-2.99) and superior to that in the MRA group (P = 0.022, RR = 0.255, 95% CI 0.09-0.71). Length of hospital stay was lower in the DUAM group compared with the DSA group (P < 0.0001) and the MRA group (P = 0.0003). The cost of DUAM is lower than that of both DSA and MRA. DUAM accurately identified the

  18. Evaluation of Anterior Ethmoidal Artery by 320-Slice CT Angiography with Comparison to Three-Dimensional Spin Digital Subtraction Angiography: Initial Experiences

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Juan; Sun, Gang; Yu, Bling Bing; Li, Min; Li, Guo Ying; Peng, Zhao Hui; Zhang, Xu Ping [Dept. of Medical Imaging, Jinan Military General Hospital, Jinan (China); Lu, Yang [Dept. of Radiology, University of Illinois College of Medicine, Illinois (United States)

    2012-11-15

    To explore the usefulness of 320-slice CT angiography (CTA) for evaluating the course of the anterior ethmoidal artery (AEA) and its relationship with adjacent structures by using three-dimensional (3D) spin digital subtraction angiography (DSA) as standard reference. From December 2008 to December 2010, 32 patients with cerebrovascular disease, who underwent both cranial 3D spin DSA and 320-slice CTA within a 30 day period from each other, were retrospectively reviewed. AEA course in ethmoid was analyzed in DSA and CTA. In addition, adjacent bony landmarks (bony notch in medial orbital wall, anterior ethmoidal canal, and anterior ethmoidal sulcus) were evaluated with CTA using the MPR technique oriented along the axial, coronal and oblique coronal planes in all patients. The dose length product (DLP) for CTA and the dose-area product (DAP) for 3D spin DSA were recorded. Effective dose (ED) was calculated. The entire course of the AEA was seen in all 32 cases (100%) with 3D spine DSA and in 29 of 32 cases (90.1%) with 320-slice CTA, with no significant difference (p = 0.24). In three cases where AEA was not visualized on 320-slice CTA, two were due to the dominant posterior ethmoidal artery, while the remaining case was due to diminutive AEA. On MPR images of 320-slice CT, a bony notch in the orbital medial walls was detected in all cases (100%, 64 of 64); anterior ethmoidal canal was seen in 28 of 64 cases (43.8%), and the anterior ethmoidal sulcus was seen in 63 of 64 cases (98.4%). The mean effective dose in CTA was 0.6 {+-} 0.25 mSv, which was significantly lower than for 3D spin DSA (1.3 {+-} 0.01 mSv) (p < 0.001). 320-slice CTA has a similar detection rate for AEA to that of 3D spin DSA; however, it is noninvasive, and may be preferentially used for the evaluation of AEA and its adjacent bony variations and pathologic changes in preoperative patients with paranasal sinus diseases.

  19. Internal carotid artery stenosis: accuracy of subjective visual impression for evaluation with digital subtraction angiography and contrast-enhanced MR angiography.

    Science.gov (United States)

    U-King-Im, Jean Marie; Graves, Martin J; Cross, Justin J; Higgins, Nicholas J; Wat, Josephine; Trivedi, Rikin A; Tang, Tjun; Howarth, Simon P S; Kirkpatrick, Peter J; Antoun, Nagui M; Gillard, Jonathan H

    2007-07-01

    To prospectively determine, for both digital subtraction angiography (DSA) and contrast material-enhanced magnetic resonance (MR) angiography, the accuracy of subjective visual impression (SVI) in the evaluation of internal carotid artery (ICA) stenosis, with objective caliper measurements serving as the reference standard. Local ethics committee approval and written informed patient consent were obtained. A total of 142 symptomatic patients (41 women, 101 men; mean age, 70 years; age range, 44-89 years) suspected of having ICA stenosis on the basis of Doppler ultrasonographic findings underwent both DSA and contrast-enhanced MR angiography. With each modality, three independent neuroradiologists who were blinded to other test results first visually estimated and subsequently objectively measured stenoses. Diagnostic accuracy and percentage misclassification for correct categorization of 70%-99% stenosis were calculated for SVI, with objective measurements serving as the reference standard. Interobserver variability was determined with kappa statistics. After exclusion of arteries that were unsuitable for measurement, 180 vessels remained for analysis with DSA and 159 vessels remained for analysis with contrast-enhanced MR angiography. With respect to 70%-99% stenosis, SVI was associated with average misclassification of 8.9% for DSA (8.9%, 7.8%, and 10.0% for readers A, B, and C, respectively) and of 11.7% for contrast-enhanced MR angiography (11.3%, 8.8%, and 15.1% for readers A, B, and C, respectively). Negative predictive values were excellent (92.3%-100%). Interobserver variability was higher for SVI (DSA, kappa = 0.62-0.71; contrast-enhanced MR angiography, kappa = 0.57-0.69) than for objective measurements (DSA, kappa = 0.75-0.80; contrast-enhanced MR angiography, kappa = 0.66-0.72). SVI alone is not recommended for evaluation of ICA stenosis with both DSA and contrast-enhanced MR angiography. SVI may be acceptable as an initial screening tool to exclude the

  20. Clinical and radiological of acute ischemic stroke patients without angiographic occlusion on digital subtraction angiogram. A pooled analysis of case series

    Energy Technology Data Exchange (ETDEWEB)

    Shah, Qaisar A.; Memon Zeeshan, Muhammad; Vazquez, Gabriela; Suri, M. Fareed K.; Hussein, Haitham M.; Qureshi, Adnan I. [Zeenat Qureshi Stroke Research Center, Department of Neurology, University of Minnesota, Minneapolis, MN (United States); Mohammad, Yousef M. [Department of Neurology, Ohio State University, Columbus, OH (United States)

    2008-11-15

    Approximately 20-30% of the patients with acute ischemic stroke do not have any occlusion demonstrated on initial digital subtraction angiography (DSA). We sought to determine the risk and rates of cerebral infarction and favorable neurological outcome in this group of acute ischemic stroke patients. Patients were identified from a prospectively maintained stroke database and from literature search of MEDLINE, PubMed, and Cochrane databases. All patients had initial neurological assessment on National Institutes of Health Stroke Scale (NIHSS). Patients then underwent DSA after initial head computed tomography (CT) scans. Follow-up radiological assessment at 24-72 h was performed with CT and magnetic resonance imaging scans. Association of stroke risk factors with clinical and radiological outcomes was estimated. A total of 81 patients was analyzed (mean age 63 years; 28 were women). The median NIHSS score was 8 (range 2-25). None of the patients received either intravenous or intra-arterial thrombolytic. Cerebral infarction was detected in 62 (76%) of the 81 patients. Twenty-four to 48-h NIHSS was available for 51 patients only. Neurological improvement was observed in 22 (43%) of the 51 patients. Favorable outcome ascertained at 3-month follow-up was seen in 48 (59%) of the 81 patients. After adjusting for age, sex, and baseline NIHSS, male patients [odds ratio (OR) 4.5 (1.4-14.3), p value=0.01] and patients with age{>=} =65 [OR 4.3 (1.2-16.2), p value=0.03] have a higher risk of cerebral infarcts on the follow-up imaging. Similarly, patients who presented with <10 NIHSS had a better 3-month outcome than those with >10 NIHSS [OR 0.21 (0.08-0.61), p value=0.004]. Ischemic stroke patients without arterial occlusion on DSA have a higher risk of cerebral infarction and disability particularly in men, patients over 65 years of age and with NIHSS{>=}=10. The cause of infarction may have been arterial obstruction with spontaneous recanalization or small vessel occlusion

  1. Optimising Optimal Image Subtraction

    CERN Document Server

    Israel, H; Schuh, S; Israel, Holger; Hessman, Frederic V.; Schuh, Sonja

    2006-01-01

    Difference imaging is a technique for obtaining precise relative photometry of variable sources in crowded stellar fields and, as such, constitutes a crucial part of the data reduction pipeline in surveys for microlensing events or transiting extrasolar planets. The Optimal Image Subtraction (OIS) algorithm permits the accurate differencing of images by determining convolution kernels which, when applied to reference images of particularly good quality, provide excellent matches to the point-spread functions (PSF) in other images of the time series to be analysed. The convolution kernels are built as linear combinations of a set of basis functions, conventionally bivariate Gaussians modulated by polynomials. The kernel parameters must be supplied by the user and should ideally be matched to the PSF, pixel-sampling, and S/N of the data to be analysed. We have studied the outcome of the reduction as a function of the kernel parameters using our implementation of OIS within the TRIPP package. From the analysis o...

  2. Conventional versus storage phosphor-plate digital images to visualize the root canal system contrasted with a radiopaque medium.

    Science.gov (United States)

    Naoum, Hani J; Chandler, Nicholas P; Love, Robert M

    2003-05-01

    The pulp tissue was removed from 20 mandibular first molar teeth using 2.5% NaOCl irrigation and hand files. The dried canals were infused with radiopaque contrast medium. Standardized conventional and Digora digital images were obtained of each tooth positioned in a dried mandible at 0- and 30-degree horizontal angulations. Three evaluators rated the image clarity of the 0- and 30-degree original, enhanced, three-dimensional, zoom, and reverse digital image modes as superior, equal, or inferior to corresponding 0- and 30-degree conventional radiographs. The ratings were compared using the Wilcoxon signed rank test. The original, three-dimensional, zoom, or reverse digital images were inferior to the conventional radiographs for clarity of canal anatomy. The enhanced digital images were not always inferior to the conventional radiographs and were the only images superior to the original digital images. Overall, evaluators rated the image clarity of root canal anatomy on conventional radiographs better than on Digora images. However, factors in the experimental design may have contributed to this result.

  3. Comparison of digital radiography and apex locator with the conventional method in root length determination of primary teeth

    Directory of Open Access Journals (Sweden)

    I E Neena

    2011-01-01

    Full Text Available Aim: The purpose of this study was to compare the Working length in primary teeth endodontics using intra oral digital radiovisiography and apex locator with conventional method for accuracy. Materials and Methods: This in vivo study was conducted on 30 primary teeth which were indicated for pulpectomy in the patients of the age group of 5-11 years All experimental teeth had adequate remaining tooth structure for rubber dam isolation and radiographicaly visible canals. Endodontic treatment was required due to irreversible pulpitis or pulp necrosis. A standardized intraoral periapical radiograph of the tooth was taken using conventional method by paralleling technique. The distance between the source and the tooth, tooth and the films were standardized using X-ray positioning device. During the pulpectomy procedure, the working length was determined by digital radiograph and apex locator. The measurements were then compared with the conventional method of root canal measurement technique for accuracy Result: From the results obtained we can conclude that Working length determined in primary molars using digital radiography and Apex locator did not show any significant difference in the mean working length measurements when compared with the conventional radiographic method. Conclusions: Apex locator is comparable to conventional radiograph in determining the working length without radiation in the primary teeth. Intraoral digital radiography is the safest method in determining the working length with significant reduction in radiation exposure.Hence, both the techniques can be safely used as alternatives to conventional radiographic methods in determining working length in primary teeth.

  4. Detection of soft tissue densities from digital breast tomosynthesis: comparison of conventional and deep learning approaches

    Science.gov (United States)

    Fotin, Sergei V.; Yin, Yin; Haldankar, Hrishikesh; Hoffmeister, Jeffrey W.; Periaswamy, Senthil

    2016-03-01

    Computer-aided detection (CAD) has been used in screening mammography for many years and is likely to be utilized for digital breast tomosynthesis (DBT). Higher detection performance is desirable as it may have an impact on radiologist's decisions and clinical outcomes. Recently the algorithms based on deep convolutional architectures have been shown to achieve state of the art performance in object classification and detection. Similarly, we trained a deep convolutional neural network directly on patches sampled from two-dimensional mammography and reconstructed DBT volumes and compared its performance to a conventional CAD algorithm that is based on computation and classification of hand-engineered features. The detection performance was evaluated on the independent test set of 344 DBT reconstructions (GE SenoClaire 3D, iterative reconstruction algorithm) containing 328 suspicious and 115 malignant soft tissue densities including masses and architectural distortions. Detection sensitivity was measured on a region of interest (ROI) basis at the rate of five detection marks per volume. Moving from conventional to deep learning approach resulted in increase of ROI sensitivity from 0:832 +/- 0:040 to 0:893 +/- 0:033 for suspicious ROIs; and from 0:852 +/- 0:065 to 0:930 +/- 0:046 for malignant ROIs. These results indicate the high utility of deep feature learning in the analysis of DBT data and high potential of the method for broader medical image analysis tasks.

  5. Comparative diagnosis in the detection of decays involving conventional methods, laser, and digital x ray

    Science.gov (United States)

    Lizarelli, Rosane F. Z.; Bregagnolo, Janete C.; Lizarelli, Renata Z.; Palhares, Juliana M. C.; Villa, Girlene E. P.; Bagnato, Vanderlei S.

    2000-03-01

    Occlusal surface caries are very difficult to diagnose at early stages, special difficulties are observed when the lesion is formed bilaterally in the pits and fissures walls. Preventive measures have been a constant concerning in the attempt to reduce the installation and progression of incipient occlusal decays. The early carious lesions detection through conventional diagnosis methods are questionable because they can end up with a risk of a false-positive or false-negative diagnosis. Using 22 teeth in vitro, premolars and molars, which suggested carious lesions, the exams were made by 3 examiners calibrated through pre-determined scores. The utilized methods were: GI -- visual inspection, GII -- tactile inspection (explorer probe), GIII -- conventional radiographic exam, GIV -- digital radiographic exam (Digora for Windows 1.51 and 1.51N, Soredex-orion Co.), GV -- low intensity laser for diagnosis (DIAGNOdent, KaVo, Germany; GVI -- histologic section. The examiners did not communicate among themselves during the exams. There were significant statistical difference among the evaluated methods. Under Friedman statistical test, GI, GIII and GIV were different from GV at the 0.1% level; when we have compared GII with GV, we observed statistical difference at the 1% level. In conclusion, GV was highly statistically different from the others groups, it means that the low intensity laser for diagnosis was the most sensible method to detect decayed tissue.

  6. Alias subtraction more efficient than conventional zero-padding in the Fourier-based calculation of the susceptibility induced perturbation of the magnetic field in MR.

    Science.gov (United States)

    Bouwman, Job G; Bakker, Chris J G

    2012-08-01

    Forward calculation of the susceptibility induced field shift by Fourier-based procedures requires spatial zero-padding to prevent aliasing artifacts (periodic wrap-around). Padding with a factor of two gives accurate results, however, halves the maximal attainable resolution, and slows down the calculation, which may hamper the feasibility of real-time calculations. Herein is proposed to first perform the calculation at the original resolution--allowing aliasing-and to remove aliasing with an additional convolution in a lower resolution, to alleviate these restrictions regarding memory size and calculation speed, a procedure we termed "virtual" zero-padding. Virtual zero-padding was numerically and experimentally tested and validated with conventional zero-padding and the analytical solution (in the case of spheres) on several phantoms. A demonstration of the increased efficiency is given by implementing virtual zero-padding in a dynamic calculation procedure. The improved efficiency is expected to be relevant regarding the ongoing increase in spatial and temporal resolution in ultra-high-field MRI. Procedures are presented for circular convolution using the discrete Green's function and k-space filtering using the continuous Green's function.

  7. Comparison of the fit of cast gold crowns fabricated from the digital and the conventional impression techniques

    Science.gov (United States)

    Jeon, Young-Chan; Jeong, Chang-Mo

    2017-01-01

    PURPOSE The purpose of this study was to compare the fit of cast gold crowns fabricated from the conventional and the digital impression technique. MATERIALS AND METHODS Artificial tooth in a master model and abutment teeth in ten patients were restored with cast gold crowns fabricated from the digital and the conventional impression technique. The forty silicone replicas were cut in three sections; each section was evaluated in nine points. The measurement was carried out by using a measuring microscope and I-Soultion. Data from the silicone replica were analyzed and all tests were performed with α-level of 0.05. RESULTS 1. The average gaps of cast gold crowns fabricated from the digital impression technique were larger than those of the conventional impression technique significantly. 2. In marginal and internal axial gap of cast gold crowns, no statistical differences were found between the two impression techniques. 3. The internal occlusal gaps of cast gold crowns fabricated from the digital impression technique were larger than those of the conventional impression technique significantly. CONCLUSION Both prostheses presented clinically acceptable results with comparing the fit. The prostheses fabricated from the digital impression technique showed more gaps, in respect of occlusal surface. PMID:28243386

  8. Evaluation of the maxillary premolar roots dissociation using radiographic holders with conventional and digital radiography

    Directory of Open Access Journals (Sweden)

    Marcia Regina Ramalho da Silva Bardauil

    2010-09-01

    Full Text Available This in vivo study evaluated the dissociation quality of maxillary premolar roots combining variations of vertical and horizontal angulations by using X-ray holders (Rinn -XCP, and made a comparison between two types of intraoral radiography systems - conventional film (Kodak Insight, Rochester, USA and digital radiography (Kodak RVG 6100, Kodak, Rochester, USA. The study sample was comprised of 20 patients with a total of 20 maxillary premolars that were radiographed, using the paralleling angle technique (GP, with a 20º variation of the horizontal angle (GM and 25º variation of the horizontal angle combined with 15º vertical angle (GMV. Each image was independently analyzed by two experienced examiners. These examiners assigned a score to the diagnostic capability of root dissociation and the measurement of the distance between the apexes. Statistical data was derived using the Wilcoxon Signed Rank test, Friedman and T test. The means of the measured distances between buccal and lingual root apexes were greater for the GMV, which ranged from 2.3 mm to 3.3 mm. A statistically significant difference was found between GM and GMV when compared to GP with p < 0.01. An established best diagnostic dissociation roots image was found in the GMV. These results support the use of the anterior X-ray holders which offer a better combined deviation (GMV to dissociate maxillary premolar roots in both radiography systems.

  9. Restoration of digital images with known space-variant blurs from conventional optical systems

    Science.gov (United States)

    Costello, Thomas P.; Mikhael, Wasfy B.

    1999-07-01

    Space-variant (SV) digital image restoration methods attempt to restore images degraded by blurs that vary over the image field. One specific source of SV blurs is that of geometrical optical aberrations, which divert light rays as they pass through the optical system away from an ideal focal point. For simple optical system, aberrations can become significant even at moderate field angles. Restoration methods have been developed for some space- variant aberrations when they are individually dominant, but such dominance is not typically characteristic of conventional optical systems. In this paper, an iterative method of restoration that is applicable to generalized, known space-variant blurs is applied to simulations of images generated with a spherical lines. The method is based on the Gauss-Seidel method of solution to systems of linear equations. The method is applied to sub-images having off- axis displacements of up to 453 pixels, and found to be superior in restoration effectiveness to Fourier methods in that range of field angles.

  10. Marginal and Internal Fit of Cobalt-Chromium Fixed Dental Prostheses Generated from Digital and Conventional Impressions

    Directory of Open Access Journals (Sweden)

    Per Svanborg

    2014-01-01

    Full Text Available Objectives. Digital impressions are increasingly used and have the potential to avoid the problem of inaccurate impressions. Only a few studies to verify the accuracy of digital impressions have been performed. The purpose of this study was to compare the marginal and internal fit of 3-unit tooth supported fixed dental prostheses (FDPs fabricated from digital and conventional impressions. Methods. Ten FDPs were produced from digital impressions using the iTero system and 10 FDPs were produced using vinyl polysiloxane (VPS impression material. A triple-scan protocol and CAD software were used for measuring and calculating discrepancies of the FDPs at 3 standard areas: mean internal discrepancy, absolute marginal gap, and cervical area discrepancy. The Mann-Whitney U test was used for analyzing the results. Results. For conventional and digital impressions, respectively, FDPs had an absolute marginal gap of 147 μm and 142 μm, cervical area discrepancy of 69 μm and 44 μm, and mean internal discrepancy of 117 μm and 93 μm. The differences were statistically significant in the cervical and internal areas (P<0.001. Significance. The results indicated that the digital impression technique is more exact and can generate 3-unit FDPs with a significantly closer fit compared to the VPS technique.

  11. Gray value differences to dentin of root posts radiographed with digital intraoral systems and conventional X-ray films.

    Science.gov (United States)

    Wicht, S; Pfeiffer, P; Rother, U; Nergiz, I; Schmage, P

    2011-01-01

    This study compared the gray value differences to dentin of titanium and FRC root posts in anterior and posterior teeth radiographed with digital intraoral systems and conventional x-ray film. Radiographic images (n=5) of titanium or fiber-reinforced composite (FRC) root posts placed in extracted teeth were taken with six digital intraoral radiographic devices and conventional x-ray film (control group). Gray value differences were evaluated between the root posts and root dentin. Statistical analyses of the results were performed with three-way and one-way ANOVA with Bonferroni-Dunn's multiple comparisons post-hoc analyses (α=0.05). Significantly higher gray value differences of titanium and FRC posts were found in anterior teeth but not in molars for XIOS, Sidexis and Visualix digital intraoral systems, but not for RVG, DenOptix and VistaScan (FRC posts). Except for DenOptix with incisors and molars and VistaScan with molars, conventional x-ray films showed significantly lower gray value differences of titanium posts in incisors and molars compared to the corresponding digital radiographs.

  12. Comparison of computerized mass detection in digital breast tomosynthesis (DBT) mammograms and conventional mammograms

    Science.gov (United States)

    Chan, Heang-Ping; Wei, Jun; Sahiner, Berkman; Hadjiiski, Lubomir; Helvie, Mark A.

    2009-02-01

    We are developing a CAD system for mass detection on digital breast tomosynthesis (DBT) mammograms. In this study, we compared the detection accuracy on DBT and conventional screen-film mammograms (SFMs). DBT mammograms were acquired with a GE prototype system at the University of Michigan. 47 cases containing the CC- and MLO-view DBT mammograms of the breast with a biopsy-proven mass and the corresponding two-view SFMs of the same breast were collected. Subjective judgment showed that the masses were much more conspicuous on DBT slices than on SFMs. The CAD system for DBT includes two parallel processes, one performs mass detection in the reconstructed DBT volume, and the other in the projection view (PV) images. The mass likelihood scores estimated for each mass candidate in the two processes are merged to differentiate masses and false positives (FPs). For detection on SFMs, we previously developed a dual system approach by fusing two single CAD systems optimized for detection of average and subtle masses, respectively. A trained neural network is used to merge the mass likelihood scores of the two single systems to reduce FPs. At the case-based sensitivities of 80% and 85%, mass detection in the DBT volume resulted in an average of 0.72 and 1.06 FPs/view, and detection in the SFMs yielded 0.94 and 1.67 FPs/view, respectively. The difference fell short of statistical significance (p=0.07) by JAFROC analysis. Study is underway to collect a larger data set and to further improve the DBT CAD system.

  13. Teaching Dental Students to Understand the Temporomandibular Joint Using MRI: Comparison of Conventional and Digital Learning Methods.

    Science.gov (United States)

    Arús, Nádia A; da Silva, Átila M; Duarte, Rogério; da Silveira, Priscila F; Vizzotto, Mariana B; da Silveira, Heraldo L D; da Silveira, Heloisa E D

    2017-06-01

    The aims of this study were to evaluate and compare the performance of dental students in interpreting the temporomandibular joint (TMJ) with magnetic resonance imaging (MRI) scans using two learning methods (conventional and digital interactive learning) and to examine the usability of the digital learning object (DLO). The DLO consisted of tutorials about MRI and anatomic and functional aspects of the TMJ. In 2014, dental students in their final year of study who were enrolled in the elective "MRI Interpretation of the TMJ" course comprised the study sample. After exclusions for nonattendance and other reasons, 29 of the initial 37 students participated in the study, for a participation rate of 78%. The participants were divided into two groups: a digital interactive learning group (n=14) and a conventional learning group (n=15). Both methods were assessed by an objective test applied before and after training and classes. Aspects such as support and training requirements, complexity, and consistency of the DLO were also evaluated using the System Usability Scale (SUS). A significant between-group difference in the posttest results was found, with the conventional learning group scoring better than the DLO group, indicated by mean scores of 9.20 and 8.11, respectively, out of 10. However, when the pretest and posttest results were compared, both groups showed significantly improved performance. The SUS score was 89, which represented a high acceptance of the DLO by the users. The students who used the conventional method of learning showed superior performance in interpreting the TMJ using MRI compared to the group that used digital interactive learning.

  14. Feed particle size evaluation: conventional approach versus digital holography based image analysis

    Directory of Open Access Journals (Sweden)

    Vittorio Dell’Orto

    2010-01-01

    Full Text Available The aim of this study was to evaluate the application of image analysis approach based on digital holography in defining particle size in comparison with the sieve shaker method (sieving method as reference method. For this purpose ground corn meal was analyzed by a sieve shaker Retsch VS 1000 and by image analysis approach based on digital holography. Particle size from digital holography were compared with results obtained by screen (sieving analysis for each of size classes by a cumulative distribution plot. Comparison between particle size values obtained by sieving method and image analysis indicated that values were comparable in term of particle size information, introducing a potential application for digital holography and image analysis in feed industry.

  15. Diagnostic accuracy of direct digital radiography and conventional radiography for proximal caries detection in primary teeth: A systematic review

    Directory of Open Access Journals (Sweden)

    Sivakumar Nuvvula

    2016-01-01

    Full Text Available Objective: The present study was conducted to uncover the diagnostic accuracy of digital versus conventional radiographic methods for the detection of proximal caries in primary teeth. Methods: Two researchers independently involved in the search process to explore Medical Subject Heading terms "dental digital radiography," "dental radiography," "bitewing," "dental caries," and "primary teeth" using PubMed, Cochrane Library, Ovid SP, and SIGLE databases. Search was confined to the articles published in English language only, with time period limit January 1996 to April 2014 and a hand search was performed to retrieve additional citations. Explicit inclusion and exclusion criteria were applied to eliminate undesired studies. Critical appraisal of the retrieved articles was done using the quality rating based on Bader and co-workers criteria. Results: A total of 129 articles were retrieved, among which 4 articles were included. All the four studies included were in vitro, of which two studies attained a high-quality score, whereas the other two attained average, and low scores based on Bader et al.′s criteria. Conclusions: A big lacuna exists in the literature, regarding the evaluation of radiographic systems in primary teeth, suggesting an immediate need for well conducted in vivo studies. The quality of available evidence can be regarded as fair but cannot be suggested to set a baseline, indicating a need to perform high-quality studies in a randomized sample to find out the accuracy of digital and conventional radiographs.

  16. Orchestrating the XO Computer with Digital and Conventional Resources to Teach Mathematics

    Science.gov (United States)

    Díaz, A.; Nussbaum, M.; Varela, I.

    2015-01-01

    Recent research has suggested that simply providing each child with a computer does not lead to an improvement in learning. Given that dozens of countries across the world are purchasing computers for their students, we ask which elements are necessary to improve learning when introducing digital resources into the classroom. Understood the…

  17. Evaluation of conventional and digital radiography capacities for distinguishing dental materials on radiograms depending on the present radiopacifying agent

    Directory of Open Access Journals (Sweden)

    Antonijević Đorđe

    2014-01-01

    Full Text Available Bacgroun/Aim. The radiopacity of an endodontic material can considerably vary as measured on film and a digital sensor. Digital radiography offers numerous advantages over convential film-based radiography in dental clinical practice regarding both diagnostic capabilities and postintervention procedures. The aim of this study was to investigate the capacity of conventional and charge-conpled device (CCD based digital radiography to detect material on radiograph depending on the radio-pacifying agent present in the material. Methods. Experimental cements were formulated by mixing Portland cement with the following radiopacifying agents: zinc oxide (ZnO, zirconium oxide (ZrO2, titanium dioxide (TiO2, barium sulphate (BaSO4, iodoform (CHI3, bismuth oxide (Bi2O3 and ytterbium trifluoride (YbF3. In addition, 5 endodontic materials comprising Endomethasone®, Diaket®, N2®, Roth 801® and Acroseal® were investigated to serve as control. Per three specimens of each material were radiographed alongside an aluminum step wedge on film (Eastman Kodak Company®, Rochester, NY and a CCD-based digital sensor (Trophy Radiologie®, Cedex, France. Radiopacity values were calculated by converting the radiographic densities of the specimens expressed as a mean optical densities or mean grey scale values into equivalent thickness of aluminum. Results. Twoway ANOVA detected no significant differences with respect to the imaging system (p > 0.05, but the differences were significant with respect to radiopacifier (p < 0.001 and the interaction of the two factors (p < 0.05. Paired ttest revealed significant differences between the methods used for pure Portland cement, all concentrations of BaSO4 and CHI3, 10% and 20% additions of ZrO2 and Bi2O3 and 10% and 30% addition of YbF3 (p < 0.05. Conclusion. The materials which incorporate CHI3 or BaSO4 as radiopacifying agents are expected to be significantly more radiopaque on a digital sensor than on film. During clinical

  18. The value of three-dimension digital subtraction angiography in cerebro-vascular diseases%3D-DSA在脑血管疾病诊断中的应用价值

    Institute of Scientific and Technical Information of China (English)

    刘康; 缪南东; 任勇军; 徐浩; 闵旭立; 杨林; 张小明

    2015-01-01

    Objective:To study the value of three-dimension digital subtraction angiography (3D-DSA) in cerebrovascular dis-eases. Methods:A retrospective analysis of 208 patients who underwent both 2D-DSA and 3D-DSA for evaluation of previously untreat-ed cerebrovascular diseases was conducted. The data of 2D-DSA and 3D-DSA images were analyzed. Results:Among the 208 patients, there are 128 patients with artery aneurysm,and 29 with artery stenosis or obstruction,22 with AVM,10 with moyamoya disease and 4 intracranial tumors. The detection rate of 2D-DSA is 80. 3%,while the rate of 3D-DSA is 92. 8%. This difference was significant in sta-tistics ( P< 0. 05 ) . Conclusion:Three-dimension DSA plays an important role in diagnosis and treatment of cerebrovascular diseases, and is an optimized and complemental imaging technique of 2D-DSA.%目的::探讨三维数字减影血管造影(three-dimension digital subtraction angiography,3D-DSA)在脑血管疾病诊断中的应用价值。方法:对临床怀疑脑血管疾病患者208例,同时进行常规DSA(2D-DSA)和3D-DSA检查,并对结果进行对比分析。结果:208例中,检出动脉瘤128例,脑动脉狭窄或闭塞29例,动静脉畸22例,烟雾病10例,脑肿瘤4例。2D-DSA病变检出率80.3%(167/208);3D-DSA病变检出率92.8%(193/208);两组检出率差异具有统计学意义(P<0.05)。结论:3D-DSA在脑血管疾病诊断中具有重要的应用价值,是2D-DSA的优化和补充。

  19. Role of biplane digital subtraction angiography, and 3D rotational angiography in craniopagus twins: A case report, detailed pictorial evaluation, and review of literature.

    Science.gov (United States)

    Sudha, Lakshmi; Dev, Bhawna; Kamble, Ravindra; Joseph, Santhosh

    2009-07-01

    Cranially conjoined twins (craniopagus) are regarded as one of the rarest human malformations. Craniopagus represents 2 to 6% of conjoined twins and is the rarest type of disorder. A conventional angiogram with three dimensions is needed to confirm the exact extent of sharing of the arterial / venous tree. 3D angiography was first proposed by CORNELIUS and advanced into clinical practice by VOIGT in 1975. We present a case of craniopagus vertical type II twins, evaluated for cerebral circulation.

  20. Role of biplane digital subtraction angiography, and 3D rotational angiography in craniopagus twins: A case report, detailed pictorial evaluation, and review of literature

    OpenAIRE

    Lakshmi Sudha; Bhawna Dev; Ravindra Kamble; Santhosh Joseph

    2009-01-01

    Cranially conjoined twins (craniopagus) are regarded as one of the rarest human malformations. Craniopagus represents 2 to 6% of conjoined twins and is the rarest type of disorder. A conventional angiogram with three dimensions is needed to confirm the exact extent of sharing of the arterial / venous tree. 3D angiography was first proposed by CORNELIUS and advanced into clinical practice by VOIGT in 1975. We present a case of craniopagus vertical type II twins, evaluated for cerebral circulat...

  1. Role of biplane digital subtraction angiography, and 3D rotational angiography in craniopagus twins: A case report, detailed pictorial evaluation, and review of literature

    Directory of Open Access Journals (Sweden)

    Lakshmi Sudha

    2009-01-01

    Full Text Available Cranially conjoined twins (craniopagus are regarded as one of the rarest human malformations. Craniopagus represents 2 to 6% of conjoined twins and is the rarest type of disorder. A conventional angiogram with three dimensions is needed to confirm the exact extent of sharing of the arterial / venous tree. 3D angiography was first proposed by CORNELIUS and advanced into clinical practice by VOIGT in 1975. We present a case of craniopagus vertical type II twins, evaluated for cerebral circulation.

  2. Suppression subtractive hybridization.

    Science.gov (United States)

    Ghorbel, Mohamed T; Murphy, David

    2011-01-01

    Comparing two RNA populations that differ from the effects of a single independent variable, such as a drug treatment or a specific genetic defect, can establish differences in the abundance of specific transcripts that vary in a population dependent manner. There are different methods for identifying differentially expressed genes. These methods include microarray, Serial Analysis of Gene Expression (SAGE), and quantitative Reverse-Transcriptase Polymerase Chain Reaction (qRT-PCR). Herein, the protocol describes an easy and cost-effective alternative that does not require prior knowledge of the transcriptomes under examination. It is specifically relevant when low levels of RNA starting material are available. This protocol describes the use of Switching Mechanism At RNA Termini Polymerase Chain Reaction (SMART-PCR) to amplify cDNA from small amounts of RNA. The amplified cDNA populations under comparison are then subjected to Suppression Subtractive Hybridization (SSH-PCR). SSH-PCR is a technique that couples subtractive hybridization with suppression PCR to selectively amplify fragments of differentially expressed genes. The resulting products are cDNA populations enriched for significantly overrepresented transcripts in either of the two input RNAs. These cDNA populations can then be cloned to generate subtracted cDNA library. Microarrays made with clones from the subtracted forward and reverse cDNA libraries are then screened for differentially expressed genes using targets generated from tester and driver total RNAs.

  3. Comparative study of dose estimation in the change a conventional mammography to digital mammography; Estudio comparativo de estimacion de dosis en el cambio de un mamografo convencional a un mamografo digital

    Energy Technology Data Exchange (ETDEWEB)

    Vazquez Vazquez, R.; Otero Martinez, C.; Soto Bua, M.; Santamarina Vazquez, F.; Carril Iglesias, S.; Lobato Busto, R.; Luna Vega, V.; Mosquera Sueiro, J.; Sqanchez Garcia, M.; Pombar Camean, M.

    2011-07-01

    Mammographic studies are now one of the most demanding radiological because of its effectiveness in detecting breast cancer early. The introduction of digital mammography has been a major advance because it has overcome some of the limitations of conventional systems. Due to the nature of the radiosensitive glandular tissue becomes very important control of the dose given to patients. In the present study is to analyze the variations in dosimetry that can exist between a conventional mammography and digital mammography.

  4. Evaluation of average glandular dose in digital and conventional systems of the mammography; Avaliacao da dose glandular media em sistemas digitais e convencionais de mamografia

    Energy Technology Data Exchange (ETDEWEB)

    Xavier, Aline C.S.; Barros, Vinicius S.M.; Khoury, Hellen J., E-mail: alinecx90@gmail.com, E-mail: vsmdbarros@gmail.com, E-mail: hjkhoury@gmail.com [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Dept. de Energia Nuclear; Mello, Francisca A. de, E-mail: francissamello@yahoo.com.br [Hospital das Clinicas do Recife (HCR/UFPE), PE (Brazil)

    2014-07-01

    Mammography is currently the most effective method of diagnosis and detection of breast pathologies. The main interest in this kid of exam comes from the high incidence rate of breast cancer and necessity of high quality images for accurate diagnosis. Digital mammography systems have several advantages compared to conventional systems, however the use of digital imaging systems is not always integrated to an image acquisition protocol. Therefore, it is questionable if digital systems truly reduce the dose received by the patient, because many times is introduced in the clinics without optimization of the image acquisition protocols. The aim of this study is to estimate the value of incident air Kerma and average glandular dose (AGD) in patients undergoing conventional and digital mammography systems in Recife. This study was conducted with 650 patients in three hospitals. The value of incident air Kerma was estimated from the measurement of the yield of equipment and irradiation parameters used for each patient. From these results and using the methodology proposed by Dance et al. the value of the average glandular dose was calculated. The results obtained show that the lowest value of AGD was found with conventional screen-film system, indicating that the parameters for image acquisition with digital systems are not optimized. It was also observed that the institutions with digital systems use lower breast compression values than the conventional. (author)

  5. [The latex agglutination with video digital registration: the enhancement of diagnostic significance of conventional technique].

    Science.gov (United States)

    Starovoĭtova, T A; Steriopolo, N A; Zaĭko, V V; Vengerov, Iu Iu

    2012-02-01

    The rapid semiquantitative latex-tests, because of their analytic characteristics and convenient application, became widespread in the practice of laboratory diagnostics. Though, in spite of high sensitivity and specificity, their diagnostic effectiveness is lower that it could be mainly because of the impossibility to document the results of latex agglutinative re4actions and to manage the objective quality control. The application of systems of video digital registration permits to enhance the clinical significance of these analyses. By means of scanner systems (control and program complex "Expert Lab") the image of analytic objects is received with the results of latex agglutination reaction. The application of program techniques (the programs "Expert Lab - Agglutination" and "Expert Lab - Agglutination - Micros") in data processing permits to get the precise qualitative characteristics of active reactions, to ensure the automatic interpretation of results and gives an opportunity to proceed with the internal laboratory quality control. The saving of analytic object image in computer memory after termination of reaction favors the formation of data base, the implementation of retrospective evaluation of obtained results, additional consultations in dubious cases, including on-line. The application of complex "Expert Lab" permitted to develop the miniaturizes matrix systems permitting to decrease the withdrawal of latex reagents, to increase the productivity of analytical stage of operation preserving all analytical characteristics of method.

  6. Conventional digital cameras as a tool for assessing leaf area index and biomass for cereal breeding

    Institute of Scientific and Technical Information of China (English)

    Jaume Casadesús; Dolors Villegas

    2014-01-01

    Affordable and easy-to-use methods for assessing biomass and leaf area index (LAI) would be of interest in most breeding programs. Here, we describe the evaluation of a protocol for photographic sampling and image analysis aimed at providing low-labor yet robust indicators of biomass and LAI. In this trial, two genotypes of triticale, two of bread wheat, and four of tritordeum were studied. At six dates during the growing cycle, biomass and LAI were measured destructively, and digital photography was taken on the same dates. Several vegetation indices were calculated from each image. The results showed that repeatable and consistent values of the indices were obtained in consecutive photographic samplings on the same plots. The photographic indices were highly correlated with the destructive measure-ments, though the magnitude of the correlation was lower after anthesis. This work shows that photographic assess-ment of biomass and LAI can be fast, affordable, have good repeatability, and can be used under bright and overcast skies. A practical vegetation index derived from pictures is the fraction of green pixels over the total pixels of the image, and as it shows good correlations with all biomass variables, is the most robust to lighting conditions and has easy interpretation.

  7. Technical innovation: Multidimensional computerized software enabled subtraction computed tomographic angiography.

    Science.gov (United States)

    Bhatia, Mona; Rosset, Antoine; Platon, Alexandra; Didier, Dominique; Becker, Christoph D; Poletti, Pierre-Alexandre

    2010-01-01

    Computed tomographic angiography (CTA) is a frequent noninvasive alternative to digital subtraction angiography. We previously reported the development of a new subtraction software to overcome limitations of adjacent bone and calcification in CT angiographic subtraction. Our aim was to further develop and improve this fast and automated computerized software, universally available for free use and compatible with most CT scanners, thus enabling better delineation of vascular structures, artifact reduction, and shorter reading times with potential clinical benefits. This computer-based free software will be available as an open source in the next release of OsiriX at the Web site http://www.osirix-viewer.com.

  8. [Comparative radiography of the respiratory tract of snakes using conventional high-resolution film-screen-system and a digital detector system].

    Science.gov (United States)

    Pees, Michael; Bochmann, Monika; Krautwald-Junghanns, Maria-Elisabeth; Schmidt, Volker; Ludewig, Eberhard

    2010-01-01

    A conventional high-resolution screen-film-system (film Kodak MIN-R S, screen Kodak MIN-R 2000) was compared to a digital detector system (Varian PaxScan 4030E) for the evaluation of the respiratory tract in snakes. Digital radiographs were taken with the same dose as well as with half the dose used for the conventional radiographs. A total of 20 Burmese pythons (Python molurus) were examined in dorsoventral and lateral projection. Four criteria (three features, one overall assessment) were defined for each of the anatomical structures lung, trachea and spinal column and assessed by five veterinarians in a semi-blinded study using a score system. Comparison of the ratings between the techniques used was done using a visual grading analysis. For the lung, two of the three features as well as the overall assessment were rated significantly superior using the digital system. The trachea was rated significantly superior using the conventional system for the overall assessment as well as for one feature. For the spinal column, the overall assessment was significantly superior using the digital system with the full dose. Conventional radiography as well as digital radiography using half the dose was rated significantly inferior for one feature each. The of the relatively low-contrast respiratory tract. A limiting factor is the demonstration of particularly small structures. Generally, a dose reduction (compared to a conventional high-resolution film-screen-system) is possible for the evaluation of the respiratory system.

  9. Clinical values of hemodynamics assessment by parametric color coding of digital subtraction angiography before and after endovascular therapy for critical limb ischaemia%彩色编码血流成像在严重下肢动脉缺血腔内治疗前后循环变化的评估价值

    Institute of Scientific and Technical Information of China (English)

    苏浩波; 楼文胜; 顾建平

    2015-01-01

    Objective To investigate the feasibility of parametric color coding of digital subtraction angiography(Syngo iFlow)for hemodynamics assessment in patients with critical limb ischemia in pre-and post-endovascular therapy.To explore the correlation between Syngo iFlow and the conventional techniques.Methods from January 2013 to December 2014,Clinical data of 21 patients with TASC Ⅱ type B and type C femoropopliteal arteriosclerotic occlusive disease who were treated by percutaneous transluminal angioplasty and/or primary stent implantation in Nanjing first hospital were analyzed retrospectively.Of these patients there were 10 males and 11 females with an average age of (72 ±6) years (range from 58-85 years).The treatment efficacy was assessed by the variation of a series of clinical symptoms indexes (such as pain score,cold sensation score and intermittent claudication score),ankle braehial index (ABI) and transcutaneous oxygen pressure (TcPO2).Angiography was performed with the same protocol before and after treatment and parametric color coding of digital subtraction angiography was created by Syngo iFlow software on a dedicated workstation.The time to peak (TTP) of artery and tissue perfusion selected at the same regions of foot and ankle were measured and analyzed to evaluate the improvement of microcirculation and hemodynamics of the ischemic limb.The correlations between Syngo iFlow and the traditional clinical evaluation methods were explored using the Spearman rank correlation test.Results All patients (21 limbs) underwent successful endovaseular therapy.The mean pain score,cold sensation score,intermittent claudication score,ABI and TcPO2 before treatment were(0.48 ± 0.68),(2.71 ± 0.72),(2.86 ± 0.85),ABI (0.33 ± 0.07),TcPO2 (26.83 ± 3.41) mmHg.While 1 week after treatment all above indicators were (2.57 ± 0.93),(0.33 ± 0.48),(0.90 ± 0.54),(0.69 ± 0.11),TcPO2 (53.75 ± 3.60) mmHg respectively.There were significant statistical differences between

  10. Digital multi-focusing from a single photograph taken with an uncalibrated conventional camera.

    Science.gov (United States)

    Cao, Yang; Fang, Shuai; Wang, Zengfu

    2013-09-01

    The demand to restore all-in-focus images from defocused images and produce photographs focused at different depths is emerging in more and more cases, such as low-end hand-held cameras and surveillance cameras. In this paper, we manage to solve this challenging multi-focusing problem with a single image taken with an uncalibrated conventional camera. Different from all existing multi-focusing approaches, our method does not need to include a deconvolution process, which is quite time-consuming and will cause ringing artifacts in the focused region and low depth-of-field. This paper proposes a novel systematic approach to realize multi-focusing from a single photograph. First of all, with the optical explanation for the local smooth assumption, we present a new point-to-point defocus model. Next, the blur map of the input image, which reflects the amount of defocus blur at each pixel in the image, is estimated by two steps. 1) With the sharp edge prior, a rough blur map is obtained by estimating the blur amount at the edge regions. 2) The guided image filter is applied to propagate the blur value from the edge regions to the whole image by which a refined blur map is obtained. Thus far, we can restore the all-in-focus photograph from a defocused input. To further produce photographs focused at different depths, the depth map from the blur map must be derived. To eliminate the ambiguity over the focal plane, user interaction is introduced and a binary graph cut algorithm is used. So we introduce user interaction and use a binary graph cut algorithm to eliminate the ambiguity over the focal plane. Coupled with the camera parameters, this approach produces images focused at different depths. The performance of this new multi-focusing algorithm is evaluated both objectively and subjectively by various test images. Both results demonstrate that this algorithm produces high quality depth maps and multi-focusing results, outperforming the previous approaches.

  11. Colourful FKS subtraction

    CERN Document Server

    Frixione, Stefano

    2011-01-01

    I formulate in a colour-friendly way the FKS method for the computation of QCD cross sections at the next-to-leading order accuracy. This is achieved through the definition of subtraction terms for squared matrix elements, constructed with single colour-dressed or pairs of colour-ordered amplitudes. The latter approach relies on the use of colour flows, is exact to all orders in $N$, and is thus particularly suited to being organized as a systematic expansion in 1/N.

  12. Computed tomography hepatic arteriography has a hepatic falciform artery detection rate that is much higher than that of digital subtraction angiography and 99mTc-MAA SPECT/CT: Implications for planning 90Y radioembolization?

    Energy Technology Data Exchange (ETDEWEB)

    Burgmans, M.C., E-mail: mburgmans@hotmail.com [Department of Diagnostic Radiology, Singapore General Hospital, Outram Road, Singapore 169608 (Singapore); Too, C.W., E-mail: too.chow.wei@singhealth.com.sg [Department of Diagnostic Radiology, Singapore General Hospital, Outram Road, Singapore 169608 (Singapore); Kao, Y.H., E-mail: yung.h.kao@gmail.com [Department of Nuclear Medicine and PET, Singapore General Hospital, Outram Road, Singapore 169608 (Singapore); Goh, A.S.W., E-mail: anthony.goh.s.w@sgh.com.sg [Department of Nuclear Medicine and PET, Singapore General Hospital, Outram Road, Singapore 169608 (Singapore); Chow, P.K.H., E-mail: gsupc@singnet.com.sg [Department of General Surgery, Singapore General Hospital, Outram Road, Singapore 169608 (Singapore); Office of Clinical Sciences, Duke-NUS Graduate Medical School Singapore, 8 College Road, Singapore 169857 (Singapore); Department of Surgical Oncology, National Cancer Center Singapore, 11 Hospital Drive, Singapore 169610 (Singapore); Tan, B.S., E-mail: tan.bien.soo@sgh.com.sg [Department of Diagnostic Radiology, Singapore General Hospital, Outram Road, Singapore 169608 (Singapore); Tay, K.H., E-mail: tay.kiang.hiong@sgh.com.sg [Department of Diagnostic Radiology, Singapore General Hospital, Outram Road, Singapore 169608 (Singapore); Lo, R.H.G., E-mail: richard.lo.h.g@sgh.com.sg [Department of Diagnostic Radiology, Singapore General Hospital, Outram Road, Singapore 169608 (Singapore)

    2012-12-15

    Purpose: To compare the hepatic falciform artery (HFA) detection rates of digital subtraction angiography (DSA), computed tomography hepatic arteriography (CTHA) and 99mTc-macroaggregated albumin (99mTc-MAA) single photon emission computed tomography with integrated CT (SPECT/CT) and to correlate HFA patency with complication rates of yttrium-90 (90Y) radioembolization. Material and methods: From August 2008 to November 2010, 79 patients (range 23–83 years, mean 62.3 years; 67 male) underwent pre-treatment DSA, CTHA and 99mTc-MAA scintigraphy (planar/SPECT/CT) to assess suitability for radioembolization with 90Y resin microspheres. Thirty-seven patients were excluded from the study, because CTHA was performed with a catheter position that did not result in opacification of the liver parenchyma adjacent to the falciform ligament. DSA, CTHA and 99mTc-MAA SPECT/CT images and medical records were retrospectively reviewed. Results: A patent HFA was detected in 22 of 42 patients (52.3%). The HFA detection rates of DSA, CTHA and 99mTc-MAA SPECT/CT were 11.9%, 52.3% and 13.3%, respectively (p < 0.0001). An origin from the segment 4 artery was seen in 51.7% of HFAs. Prophylactic HFA coil-embolization prior to 90Y microspheres infusion was performed in 2 patients. Of the patients who underwent radioembolization with a patent HFA, none developed supra-umbilical radiation dermatitis. One patient experienced epigastric pain attributed to post-embolization syndrome and was managed conservatively. Conclusion: The HFA detection rate of CTHA is superior to that of DSA and 99mTc-MAA SPECT/CT. Complications related to non-target radiation of the HFA vascular territory rarely occur, even in patients undergoing radioembolization with a patent HFA.

  13. Image Quality and Stenosis Assessment of Non-Contrast-Enhanced 3-T Magnetic Resonance Angiography in Patients with Peripheral Artery Disease Compared with Contrast-Enhanced Magnetic Resonance Angiography and Digital Subtraction Angiography.

    Science.gov (United States)

    Liu, Jiayi; Zhang, Nan; Fan, Zhaoyang; Luo, Nan; Zhao, Yike; Bi, Xiaoming; An, Jing; Chen, Zhong; Liu, Dongting; Wen, Zhaoying; Fan, Zhanming; Li, Debiao

    2016-01-01

    To evaluate the diagnostic performance of flow-sensitive dephasing (FSD)-prepared steady-state free precession (SSFP) magnetic resonance angiography (MRA) at 3 T for imaging infragenual arteries relative to contrast-enhanced MRA (CE-MRA) and digital subtraction angiography (DSA). A series of 16 consecutive patients with peripheral arterial disease (PAD) underwent a combined peripheral MRA protocol consisting of FSD-MRA for the calves and large field-of-view CE-MRA. DSA was performed on all patients within 1 week of the MR angiographies. Image quality and degree of stenosis was assessed by two readers with rich experience. Inter-observer agreement was determined using kappa statistics. Receiver operating characteristic (ROC) curve analysis determined the diagnostic value of FSD-MRA, CE-MRA, and CE-MRA combined with FSD-MRA (CE+FSD MRA) in predicting vascular stenosis. At the calf station, no significantly difference of subjective image quality scores was found between FSD-MRA and CE-MRA. Inter-reader agreement was excellent for both FSD-MRA and CE-MRA. Both of FSD-MRA and CE-MRA carry a stenosis overestimation risk relative to DSA standard. With DSA as the reference standard, ROC curve analysis showed that the area under the curve was largest for CE+FSD MRA. The greatest sensitivity and specificity were obtained when a cut-off stenosis score of 2 was used. In patients with severe PAD,3 T FSD-MRA provides good-quality diagnostic images without a contrast agent and is a good supplement for CE-MRA. CE+FSD MRA can improve the accuracy of vascular stenosis diagnosis.

  14. Intra-arterial MR-angiography on an open-bore MR-scanner compared to digital-subtraction angiography of the infra-popliteal runoff in patients with peripheral arterial occlusive disease

    Energy Technology Data Exchange (ETDEWEB)

    Huegli, Rolf W. [Department of Radiology University Hospital of Basel, Petersgraben 4, 4031 Basel (Switzerland)], E-mail: rhuegli@uhbs.ch; Thalhammer, Christoph [Department of Angiology, University Hospital of Basel, Petersgraben 4, 4031 Basel (Switzerland)], E-mail: cthalhammer@uhbs.ch; Jacob, Augustinus L. [Department of Radiology University Hospital of Basel, Petersgraben 4, 4031 Basel (Switzerland)], E-mail: ajacob@uhbs.ch; Jaeger, Kurt [Department of Angiology, University Hospital of Basel, Petersgraben 4, 4031 Basel (Switzerland)], E-mail: kjaeger@uhbs.ch; Bilecen, Deniz [Department of Radiology University Hospital of Basel, Petersgraben 4, 4031 Basel (Switzerland)], E-mail: dbilecen@uhbs.ch

    2008-06-15

    Purpose: To evaluate the diagnostic value of contrast-enhanced intra-arterial 3D-MR-angiography (IA-MRA) of the infra-popliteal arteries in an open-bore magnet. Number, severity of arterial lesions, and artefacts were compared to routinely performed intra-arterial digital-subtraction angiography (IA-DSA) in patients suffering from symptomatic peripheral arterial occlusive disease (PAOD). Material and methods: Fifteen patients admitted for PAOD underwent percutaneous transluminal angioplasty (PTA) by IA-DSA. After PTA, IA-MRA of the infra-popliteal station was performed on an open-bore 1.5 T MR-scanner applying a low dose intra-arterial contrast-enhanced 3D-gradient-echo-MRA with gadopentate dimeglumine. The reading was performed by three blinded readers distinguishing moderate ({<=}50%), significant stenoses (51-99%) and vessel occlusions. Imaging artefacts were recorded and binary classified as not disturbing or compromising the observation of the arterial tree. Results: Overall IA-DSA revealed 36 moderate stenoses ({<=}50%), 38 significant stenoses (51-99%), and 10 vessel occlusions. For the detection of significant stenoses and occlusions, the overall sensitivity, specificity, positive predictive value, negative predictive value and accuracy of IA-MRA were 96%, 83%, 88%, 94% and 90%. The only observed artefact was venous overlay in four stations. The readout was not hampered in any case. Conclusion: Intra-arterial contrast-enhanced 3D-gradient-echo-MRA on an open-bore MR-scanner offers an acceptable diagnostic accuracy in diagnosing peripheral arterial occlusive disease in the infra-popliteal region and correlates well with DSA.

  15. Pulse subtraction Doppler

    Science.gov (United States)

    Mahue, Veronique; Mari, Jean Martial; Eckersley, Robert J.; Caro, Colin G.; Tang, Meng-Xing

    2010-01-01

    Recent advances have demonstrated the feasibility of molecular imaging using targeted microbubbles and ultrasound. One technical challenge is to selectively detect attached bubbles from those freely flowing bubbles and surrounding tissue. Pulse Inversion Doppler is an imaging technique enabling the selective detection of both static and moving ultrasound contrast agents: linear scatterers generate a single band Doppler spectrum, while non-linear scatterers generate a double band spectrum, one being uniquely correlated with the presence of contrast agents and non-linear tissue signals. We demonstrate that similar spectrums, and thus the same discrimination, can be obtained through a Doppler implementation of Pulse Subtraction. This is achieved by reconstructing a virtual echo using the echo generated from a short pulse transmission. Moreover by subtracting from this virtual echo the one generated from a longer pulse transmission, it is possible to fully suppress the echo from linear scatterers, while for non-linear scatterers, a signal will remain, allowing classical agent detection. Simulations of a single moving microbubble and a moving linear scatterer subject to these pulses show that when the virtual echo and the long pulse echo are used to perform pulsed Doppler, the power Doppler spectrum allows separation of linear and non-linear moving scattering. Similar results are obtained on experimental data acquired on a flow containing either microbubble contrast agents or linear blood mimicking fluid. This new Doppler method constitutes an alternative to Pulse Inversion Doppler and preliminary results suggest that similar dual band spectrums could be obtained by the combination of any non-linear detection technique with Doppler demodulation.

  16. Effectiveness of ProTaper Universal® and D-RaCe® retreatment files in the removal of root canal filling material: an in vitro study using digital subtraction radiography

    Directory of Open Access Journals (Sweden)

    Caroline Zanesco

    2014-01-01

    Full Text Available Aim: To compare the effectiveness of the ProTaper Universal ® Retreatment system, the D-Race ® NiTi system and Hedströem fi les for removal of fi lling material from curved root canals. Methodology: A total of 39 fi rst mandibular molars were selected and their mesiobuccal (MB canals were used for the study. Teeth were assigned to one of three identical groups (n = 13 per group according to removal technique: G1 – ProTaper Universal ® Retreatment (D1, D2, D3; G2 – D-RaCe ® (DR1, DR2; or G3 – Hedströem fi les (35, 30, 25, 20. In all groups, supplementary fi les were used for re-preparation. Digital subtraction radiography images were produced by superimposing the fi rst radiograph, taken after fi lling the canal, over the second, taking after removal of the fi lling, in buccolingual (BL and mesiodistal (MD projections. Quantitative data were analyzed using intraclass correlation coef fi cients and the Kruskal-Wallis and Friedman non-parametric tests (p ≤ 0.05. Results: Comparison of groups detected no differences in fi lling removal between teeth in the ProTaper Universal ® Retreatment, D-RaCe ® or Hedströem fi le groups for the cervical or mid thirds (for either MD or BL projections. In the apical third (MD projection, ProTaper Universal ® Retreatment produced the best results; and Hedströem fi les exhibited the worst results (MD projection. Intra-group comparisons showed that the cervical third was the cleanest and the apical third was the least well-cleaned, for the ProTaper Universal ® Retreatment and D-RaCe ® groups (MD projection, while less fi lling material was removed using Hedströem when the canals approached the apical third (MD and BL projections. Conclusions: Our fi ndings indicate that the ProTaper Universal ® Retreatment system is the best choice for endodontic fi lling material removal, combined with supplementary instrumentation to achieve better results in the apical third.

  17. Advanced Background Subtraction Applied to Aeroacoustic Wind Tunnel Testing

    Science.gov (United States)

    Bahr, Christopher J.; Horne, William C.

    2015-01-01

    An advanced form of background subtraction is presented and applied to aeroacoustic wind tunnel data. A variant of this method has seen use in other fields such as climatology and medical imaging. The technique, based on an eigenvalue decomposition of the background noise cross-spectral matrix, is robust against situations where isolated background auto-spectral levels are measured to be higher than levels of combined source and background signals. It also provides an alternate estimate of the cross-spectrum, which previously might have poor definition for low signal-to-noise ratio measurements. Simulated results indicate similar performance to conventional background subtraction when the subtracted spectra are weaker than the true contaminating background levels. Superior performance is observed when the subtracted spectra are stronger than the true contaminating background levels. Experimental results show limited success in recovering signal behavior for data where conventional background subtraction fails. They also demonstrate the new subtraction technique's ability to maintain a proper coherence relationship in the modified cross-spectral matrix. Beam-forming and de-convolution results indicate the method can successfully separate sources. Results also show a reduced need for the use of diagonal removal in phased array processing, at least for the limited data sets considered.

  18. Evaluation of diagnostic ability of CCD digital radiography in the detection of incipient dental caries

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Wan; Lee, Byung Do [Wonkwang University College of Medicine, Iksan (Korea, Republic of)

    2003-03-15

    The purpose of this experiment was to evaluate the diagnostic ability of a CCD-based digital system (CDX-2000HQ) in the detection of incipient dental caries. 93 extracted human teeth with sound proximal surfaces and interproximal artificial cavities were radiographed using 4 imaging methods. Automatically processed No.2 Insight film (Eastman Kodak Co., U.S.A.) was used for conventional radiography, scanned images of conventional radiograms for indirect digital radiography were used. For the direct digital radiography, the CDX-2000HQ CCD system (Biomedisys Co. Korea) was used. The subtraction images were made from two direct digital images by Sunny program in the CDX-2000HQ system. Two radiologists and three endodontists examined the presence of lesions using a five-point confidence scale and compared the diagnostic ability by ROC (Receiver Operating Characteristic) analysis and one way ANOVA test. The mean ROC areas of conventional radiography, indirect digital radiography, direct digital radiography, and digital subtraction radiography were 0.9093, 0.9102, 0.9184, and 0.9056, respectively. The diagnostic ability of direct digital radiography was better than the other imaging modalities, but there were no statistical differences among these imaging modalities (p>0.05). These results indicate that new CCD-based digital systems (CDX-2000HQ) have the potential to serve as an alternative to conventional radiography in the detection of incipient dental caries.

  19. Diagnostic Accuracy of Digital and Conventional Radiography in the Detection of Non-Cavitated Approximal Dental Caries

    Directory of Open Access Journals (Sweden)

    Farida Abesi

    2012-03-01

    Full Text Available Background: Radiography plays an important role in the detection of interproximal caries.Objectives: The aim of the present study was to determine diagnostic accuracy of chargecoupled devices (CCD, Photo Stimulable Phosphor (PSP and film radiography in detecting non-cavitated caries.Patients and Methods: Seventy-two non-cavitated approximal surfaces of extracted human posterior teeth were radiographed under standardized conditions using three intraoral modalities: CCD Dixi3 (Planmeca, Finland, PSP Digora PCT (Soredex, Finland, and E-speed film (Kodak, USA. Radiographs were interpreted by four observers and caries lesions were classified as sound (R0, restricted to enamel (R1, reaching the dentinoenamel junction (DEJ and the outer half of the dentin (R2 and the inner half of the dentin (R3. The teeth were subsequently sectioned for histological analysis which served as the gold standard for radiographic examination.Results: Microscopic examinations showed that the distribution of caries were 63.9% sound, 18.1% enamel, 9.7% DEJ and outer half of the dentin and 8.3% into the inner half of the dentin.The sensitivity and specificity of film, CCD and PSP for the detection of enamel caries were 38% and 98%; 15% and 96 %; and 23% and 98%, respectively. The sensitivity and specificity of film, CCD and PSP for the detection of both dentin and enamel caries were 55% and 100%; 45% and 100% ; and 55% and 100%, respectively.Conclusions: The results demonstrated that the diagnostic accuracy of digital images is similar to that of conventional film radiography in the detection of non-cavitated approximal caries.

  20. Background subtraction theory and practice

    CERN Document Server

    Elgammal, Ahmed

    2014-01-01

    Background subtraction is a widely used concept for detection of moving objects in videos. In the last two decades there has been a lot of development in designing algorithms for background subtraction, as well as wide use of these algorithms in various important applications, such as visual surveillance, sports video analysis, motion capture, etc. Various statistical approaches have been proposed to model scene backgrounds. The concept of background subtraction also has been extended to detect objects from videos captured from moving cameras. This book reviews the concept and practice of back

  1. Developing a Model to Support Students in Solving Subtraction

    Directory of Open Access Journals (Sweden)

    Nila Mareta Murdiyani

    2013-01-01

    Full Text Available Subtraction has two meanings and each meaning leads to the differentstrategies. The meaning of “taking away something” suggests a directsubtraction, while the meaning of “determining the difference betweentwo numbers” is more likely to be modeled as indirect addition. Manyprior researches found that the second meaning and second strategy rarely appeared in the mathematical textbooks and teacher explanations, including in Indonesia. Therefore, this study was conducted to contribute to the development of a local instruction theory for subtraction by designing instructional activities that can facilitate first grade of primary school students to develop a model in solving two digit numbers subtraction. Consequently, design research was chosen as an appropriate approach for achieving the research aim and Realistic Mathematics Education (RME was used as a guide to design the lesson. This study involved 6 students in the pilot experiment, 31 students in the teaching experiment, and a first grade teacher of SDN 179 Palembang. The result of this study shows that the beads string could bridge students from the contextual problems (taking ginger candies and making grains bracelets to the use of the empty number line. It also shows that the empty number line could promote students to use different strategies (direct subtraction, indirect addition, and indirect subtraction in solving subtraction problems. Based on these findings, it is recommended to apply RME in the teaching learning process to make it more meaningful for students.

  2. Randomized controlled within-subject evaluation of digital and conventional workflows for the fabrication of lithium disilicate single crowns. Part II: CAD-CAM versus conventional laboratory procedures.

    Science.gov (United States)

    Sailer, Irena; Benic, Goran I; Fehmer, Vincent; Hämmerle, Christoph H F; Mühlemann, Sven

    2017-07-01

    Clinical studies are needed to evaluate the entire digital and conventional workflows in prosthetic dentistry. The purpose of the second part of this clinical study was to compare the laboratory production time for tooth-supported single crowns made with 4 different digital workflows and 1 conventional workflow and to compare these crowns clinically. For each of 10 participants, a monolithic crown was fabricated in lithium disilicate-reinforced glass ceramic (IPS e.max CAD). The computer-aided design and computer-aided manufacturing (CAD-CAM) systems were Lava C.O.S. CAD software and centralized CAM (group L), Cares CAD software and centralized CAM (group iT), Cerec Connect CAD software and lab side CAM (group CiL), and Cerec Connect CAD software with centralized CAM (group CiD). The conventional fabrication (group K) included a wax pattern of the crown and heat pressing according to the lost-wax technique (IPS e.max Press). The time for the fabrication of the casts and the crowns was recorded. Subsequently, the crowns were clinically evaluated and the corresponding treatment times were recorded. The Paired Wilcoxon test with the Bonferroni correction was applied to detect differences among treatment groups (α=.05). The total mean (±standard deviation) active working time for the dental technician was 88 ±6 minutes in group L, 74 ±12 minutes in group iT, 74 ±5 minutes in group CiL, 92 ±8 minutes in group CiD, and 148 ±11 minutes in group K. The dental technician spent significantly more working time for the conventional workflow than for the digital workflows (P.05). Irrespective of the CAD-CAM system, the overall laboratory working time for a digital workflow was significantly shorter than for the conventional workflow, since the dental technician needed less active working time. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  3. Developing a Model to Support Students in Solving Subtraction

    Directory of Open Access Journals (Sweden)

    Nila Mareta Murdiyani

    2013-01-01

    Full Text Available Subtraction has two meanings and each meaning leads to the different strategies. The meaning of “taking away something” suggests a direct subtraction, while the meaning of “determining the difference between two numbers” is more likely to be modeled as indirect addition. Many prior researches found that the second meaning and second strategy rarely appeared in the mathematical textbooks and teacher explanations, including in Indonesia. Therefore, this study was conducted to contribute to the development of a local instruction theory for subtraction by designing instructional activities that can facilitate first grade of primary school students to develop a model in solving two digit numbers subtraction. Consequently, design research was chosen as an appropriate approach for achieving the research aim and Realistic Mathematics Education (RME was used as a guide to design the lesson. This study involved 6 students in the pilot experiment, 31 students in the teaching experiment, and a first grade teacher of SDN 179 Palembang. The  result of this study shows that the beads string could bridge students from the contextual problems (taking ginger candies and making grains bracelets to the use of the empty number line. It also shows that the empty number line could promote students to  use different strategies (direct subtraction, indirect addition, and indirect subtraction in solving subtraction problems. Based on these findings, it is recommended to apply RME in the teaching learning process to make it more meaningful for students. Keywords: Subtraction, Design Research, Realistic Mathematics Education, The Beads String, The Empty Number Line DOI: http://dx.doi.org/10.22342/jme.4.1.567.95-112

  4. Digital film viewer conventional view boxes in the identification of bone and joint disorders; Diafanoscopio digitale vs tradizionale nell'identificazione delle malattie osteo-articolari

    Energy Technology Data Exchange (ETDEWEB)

    Magarelli, N. [Chieti Univ. G. D' Annunzio, Chieti (Italy). Ist. di Scienze Radiologiche e Formazione dell' Immagine; Guglielmi, G. [IRRCCS Ospedale Casa Sollievo della Sofferenza, S. Giovanni Rotondo, FG (Italy); Mattei, P.A. [Chieti Univ. G. D' Annunzio, Chieti (Italy). Facolta' di Medicina e Chirurgia; Mattioli, M.G.; Riario Sforza, A.

    1999-10-01

    The aim of this report is to compare the diagnostic accuracy of a digital film viewer (Smartlight 2000 Plus) versus a conventional view box for the identification of bone and joint disorders. [Italian] Scopo di questo studio e' confrontare l'accuratezza del diafanoscopio digitale (Smartlight 2000 Plus) con quella del diafanoscopio tradizionale nell'identificazione delle lesioni osteo-articolari.

  5. ROC comparison of visualisation of fractures of the hand via digital and conventional techniques; ROC-Vergleich der Erkennbarkeit von Frakturen der Hand mittels digitaler und konventioneller Technik

    Energy Technology Data Exchange (ETDEWEB)

    Hofstetter, H. [Stadtspital Triemli, Zurich (Switzerland). Inst. fuer Roentgendiagnostik; Voegeli, E. [Kantonspital, Luzern (Switzerland). Roentgeninstitut

    1997-09-01

    Purpose: To compare the accuracy of digital luminescence radiography (DLR) and conventional film-screen radiography (FSR) in diagnosing fractures. Material and method: Both conventional and digital radiographs were acquired from a consecutive series of 57 patients with suspected wrist or hand fractures. The digital images were obtained with a 30% dose reduction. A ROC-analysis (receiver-operating characteristics) was performed. Results: The area under the curve was 0.89 for conventional FSR, 0.93 for DLR, `gray scale` and 0.94 for DLR, `edge enhanced`. (orig./AF) [Deutsch] Ziel: Vergleich der diagnostischen Sicherheit der digitalen Lumineszenzradiographie (DLR) mit der konventionellen Film-Folien-Technik (FFT) in der Beurteilung frischer ossaerer Laesionen nach Trauma im Handbereich. Material und Methodik: Bei 57 Patienten wurden sowohl konventionelle als auch digitale Aufnahmen des Unterarmes respektive der Hand durchgefuehrt. Die digitalen Aufnahmen wurden mit einer gegenueber der FFT um 30% geringeren Expositionsdosis angefertigt. Eine ROC-Studie. Ergebnisse: Die Flaeche unter der ROC-Kurve betrug fuer die FFT 0,89, fuer die DLR, konventionell angeglichen 0,94 und fuer die DLR, kantenbetont 0,95. (orig./AJ)

  6. Digital subtraktion

    DEFF Research Database (Denmark)

    Mussmann, Bo Redder

    2004-01-01

    Digital subtraktion er en metode til at fjerne uønskede oplysninger i et røntgenbillede. Subtraktionsteknikken bruges primært i forbindelse med angiografi hvor man kun er interesseret i at se selve karret. Derfor er digital subtraktion i daglig tale synonymt med DSA eller DVI – hhv. Digital...... Subtraction Angiography eller Digital Vascular Imaging. Benævnelserne er to røntgenfirmaers navn for den samme teknik. Digital subtraktion kræver speciel software, samt at apparaturet kan eksponere i serier....

  7. Application of preoperative systematic health education in digital subtraction angiography%术前系统性健康教育在数字减影全脑血管造影中的应用

    Institute of Scientific and Technical Information of China (English)

    马学英; 陈建伟; 宋淑霞; 袁桂敏; 宋立霞; 王青青

    2012-01-01

    目的:探讨术前系统性健康教育在数字减影全脑血管造影(DSA)中的应用效果.方法:将124例住院行DSA的患者随机分为观察组与对照组各62例.对照组按常规进行宣教,2 d内共进行3次.观察组成立由2名主管护师和2名护师组成的健康教育小组,制订系统性健康教育计划表和时间表,根据DSA术前、术中及术后的基础护理知识确定DSA前的教育内容,并制成小册子和图片,根据患者的身心状况,面对面地对患者和家属实施个体化的心理护理和疾病健康指导,2 d内共3次,并对主要内容和注意事项进行提问,直到患者和家属掌握为止.结果:与对照组同期比较,观察组术前教育后和术后SAS评分明显降低(P<0.01),且观察组术后并发症明显少于对照组(P<0.01,P<0.05).结论:对DSA患者术前进行系统性健康教育可明显改善其心理状态,提高其治疗依从性,减少术后并发症.%Objective: To investigate the application effect of preoperative systematic health education in digital subtraction angiography ( DSA ). Methods: 124 hospitalized patients who would undergo DSA were randomly divided into an observation group and a control group ( 62 cases in each group ). The routine health education was conducted for 3 times within 2 days in the control group; the preoperative systematic health education program and schedule were formulated by the group composed of 2 nurses in - charge and 2 nurses, and the contents of preoperative health education were compiled according to the basic nursing knowledge of DSA in preoperative, intraoperative and postoperative period. The individualized psychological care and health guidance were given to the patients and their families 3 times in 2 days according to the patients physical and mental conditions by using booklet and pictures. Results: SAS score significantly decreased after health education and after surgery in the observation group compared with control

  8. Comparing the efficiency of digital and conventional soil mapping to predict soil types in a semi-arid region in Iran

    Science.gov (United States)

    Zeraatpisheh, Mojtaba; Ayoubi, Shamsollah; Jafari, Azam; Finke, Peter

    2017-05-01

    The efficiency of different digital and conventional soil mapping approaches to produce categorical maps of soil types is determined by cost, sample size, accuracy and the selected taxonomic level. The efficiency of digital and conventional soil mapping approaches was examined in the semi-arid region of Borujen, central Iran. This research aimed to (i) compare two digital soil mapping approaches including Multinomial logistic regression and random forest, with the conventional soil mapping approach at four soil taxonomic levels (order, suborder, great group and subgroup levels), (ii) validate the predicted soil maps by the same validation data set to determine the best method for producing the soil maps, and (iii) select the best soil taxonomic level by different approaches at three sample sizes (100, 80, and 60 point observations), in two scenarios with and without a geomorphology map as a spatial covariate. In most predicted maps, using both digital soil mapping approaches, the best results were obtained using the combination of terrain attributes and the geomorphology map, although differences between the scenarios with and without the geomorphology map were not significant. Employing the geomorphology map increased map purity and the Kappa index, and led to a decrease in the 'noisiness' of soil maps. Multinomial logistic regression had better performance at higher taxonomic levels (order and suborder levels); however, random forest showed better performance at lower taxonomic levels (great group and subgroup levels). Multinomial logistic regression was less sensitive than random forest to a decrease in the number of training observations. The conventional soil mapping method produced a map with larger minimum polygon size because of traditional cartographic criteria used to make the geological map 1:100,000 (on which the conventional soil mapping map was largely based). Likewise, conventional soil mapping map had also a larger average polygon size that resulted

  9. Voxel significance mapping in epilepsy studies using subtraction ictal SPECT

    Science.gov (United States)

    Brinkmann, Benjamin H.; O'Brien, Terence J.; Webster, Desmond B.; Robins, Peter D.; Mullan, Brian P.; Robb, Richard A.

    1999-05-01

    Subtraction ictal SPECT coregistered to MRI (SISCOM) has been shown to aid epileptogenic localization and improve surgical outcomes in partial epilepsy patients. This paper reports a new method of identifying significant areas of epileptogenic activation in the SISCOM subtraction image taking into account normal variation between sequential Tc-99m Ethyl Cysteinate Diethylester SPECT scans of single individuals. The method uses the AIR 3.0 nonlinear registration software to combine a group of subtraction images into a common anatomical framework. A map of the pixel intensity standard deviation values in the subtraction images is created, and this map is nonlinearly registered to a patient's SISCOM subtraction image. Pixels in the patient subtraction image may then be evaluated based upon the statistical characteristics of corresponding pixels in the atlas. Validation experiments were performed to verify that local image variances are not constant across the image and that nonlinear registration preserves local image variances. SISCOM images created with the voxel variance method were rated higher in quality than the conventional image variance method in images from fifteen patients. No difference in localization rate was observed between the voxel variance mapping and image variance methods. The voxel significance mapping method was shown to improve the quality of clinical SISCOM images without removing localizing information.

  10. Radiation dose to patients and radiologists during transcatheter arterial embolization: comparison of a digital flat-panel system and conventional unit.

    Science.gov (United States)

    Suzuki, Shigeru; Furui, Shigeru; Kobayashi, Ikuo; Yamauchi, Teiyu; Kohtake, Hiroshi; Takeshita, Koji; Takada, Koichi; Yamagishi, Masafumi

    2005-10-01

    The objective of our study was to evaluate the exposure doses to patients and radiologists during transcatheter arterial embolization (TAE) for hepatocellular carcinoma (HCC) using a new angiographic unit with a digital flat-panel system. Doses were assessed for 24 procedures: 12 using a new unit with a digital flat-panel system and 12 using a conventional unit. Doses to patients' skin were evaluated with thermoluminescent dosimeters behind the left, middle, and right portions of the liver. The doses to the radiologists were measured by an electronic personal dosimeter placed on the chest outside a lead protector. The maximal skin doses to the patients and the dose equivalents, Hp(0.07), to the radiologists were compared between the two procedure groups with each angiographic unit. For procedures with the new unit, the mean maximal skin dose to the patients was 284 +/- 127 (SD) mGy (range, 130-467 mGy), and Hp(0.07) to the radiologists was 62.8 +/- 17.4 muSv. For procedures with the conventional unit, the maximal skin dose to the patients was 1,068 +/- 439 mGy (range, 510-1,882 mGy), and Hp(0.07) to the radiologists was 68.4 +/- 25.7 muSv. The maximal skin dose to the patients was significantly lower with the new unit than with the conventional unit (p < 0.0005). There was no significant difference in the Hp(0.07) to the radiologists between the two procedure groups. The new digital flat-panel system for angiographic imaging can reduce the radiation dose to patients' skin during TAE for HCC as compared with the conventional system.

  11. Digitization

    DEFF Research Database (Denmark)

    Finnemann, Niels Ole

    2014-01-01

    Processes of digitization have for years represented a major trend in the developments of modern society but have only recently been related to processes of mediatization. The purpose of this article is to look into the relation between the concepts of mediatization and digitization and to clarify...... what a concept of digital media might add to the understanding of processes of mediatization and what the concept of mediatization might add to the understanding of digital media. It is argued that digital media open an array of new trajectories in human communication, trajectories which were...... not anticipated in previous conceptualizations of media and mediatization. If digital media are to be included, the concept of mediatization has to be revised and new parameters are to be built into the concept of media. At the same time it is argued that the concept of mediatization still provides a variety...

  12. Color Addition and Subtraction Apps

    Science.gov (United States)

    Ruiz, Frances; Ruiz, Michael J.

    2015-10-01

    Color addition and subtraction apps in HTML5 have been developed for students as an online hands-on experience so that they can more easily master principles introduced through traditional classroom demonstrations. The evolution of the additive RGB color model is traced through the early IBM color adapters so that students can proceed step by step in understanding mathematical representations of RGB color. Finally, color addition and subtraction are presented for the X11 colors from web design to illustrate yet another real-life application of color mixing.

  13. Digital subtraction angiography of predominant artery feeding pancreatic body and tail%胰体尾优势供血动脉的数字减影血管造影

    Institute of Scientific and Technical Information of China (English)

    吴志贤; 蔡锦全; 杨熙章; 廖联明; 罗芳; 杨利; 林宇宁; 谭建明

    2013-01-01

    Objective To investigate the anatomical characteristics of predominant artery feeding pancreatic body and tail (PBT). Methods One hundred and eight patients with diabetes (61 males and 47 females) underwent digital subtraction angiography ( DSA). Selective DSA of the celiac trunk, gastroduodenal artery, and superior mesenteric artery were performed to localize the potential predominant feeding artery of the PBT. The feeding artery was catheterized and DSA was performed. All images were documented for later analysis. Results The feeding arteries for the PBT included the sole dorsal pancreatic artery ( DPA, 58. 3% ) , sole great pancreatic artery (GPA, 13. 9% ) , both DPA and GPA (11. 1% ) , and transverse pancreatic artery (TPA, 14.8%). The DPA originated from the first segment of the splenic artery (52.0%), common hepatic artery (21.3%), or superior mesenteric artery (24.0%). The GPA was mostly from the middle segment of the splenic artery (96. 3% ) The TPA was from either the gastroduodenal artery (68. 8% ) or the pancreaticoduodenal artery (31.2% ). Conclusion The origins and identities of the predominant artery in the PBT are variable, which require comprehensive study before interventional therapy for diabetic patients.%目的 采用数字减影血管造影(DSA)方法,研究糖尿病患者胰体尾优势供血动脉的解剖特点,为临床胰腺介入治疗提供血管解剖依据.方法 糖尿病患者108例,男61例,女47例,于介入治疗手术室行胰体尾动脉造影.第一阶段进行腹腔干、胃十二指肠动脉、肠系膜上动脉造影,初步定位胰尾体部优势供血动脉,之后将导管直接置入目标动脉,行DSA,观察胰体尾显影情况.如置入失败,则采用脾动脉远端球囊堵塞近端造影的方法,对胰体尾进行显影.保存介入影像进行分析.结果 造影显示,胰体尾优势供血动脉分别为胰背动脉(58.3%,63/108)、胰大动脉(13.9%,15/108)、胰背动脉联合胰大动脉(11.1%,12/108)

  14. Behavior Subtraction applied to radar

    NARCIS (Netherlands)

    Rossum, W.L. van; Caro Cuenca, M.

    2014-01-01

    An algorithm developed for optical images has been applied to radar data. The algorithm, Behavior Subtraction, is based on capturing the dynamics of a scene and detecting anomalous behavior. The radar application is the detection of small surface targets at sea. The sea surface yields the expected s

  15. Color Addition and Subtraction Apps

    Science.gov (United States)

    Ruiz, Frances; Ruiz, Michael J.

    2015-01-01

    Color addition and subtraction apps in HTML5 have been developed for students as an online hands-on experience so that they can more easily master principles introduced through traditional classroom demonstrations. The evolution of the additive RGB color model is traced through the early IBM color adapters so that students can proceed step by step…

  16. Color Addition and Subtraction Apps

    Science.gov (United States)

    Ruiz, Frances; Ruiz, Michael J.

    2015-01-01

    Color addition and subtraction apps in HTML5 have been developed for students as an online hands-on experience so that they can more easily master principles introduced through traditional classroom demonstrations. The evolution of the additive RGB color model is traced through the early IBM color adapters so that students can proceed step by step…

  17. Subtraction and dynamic MR images of breast cancer

    Energy Technology Data Exchange (ETDEWEB)

    Murakami, Yoshitaka; Aoki, Manabu; Harada, Junta (Jikei Univ., Tokyo (Japan). School of Medicine)

    1993-04-01

    The purpose of this study was to evaluate the diagnostic effectiveness of subtraction and dynamic MR imaging in patients with breast masses. In 23 breast cancers and six fibroadenomas, spin echo T1 images were obtained at 0.2 Tesla before and every minute after intravenous injection of Gd-DTPA (0.1 or 0.2 mmol/kg). Subtraction images were obtained sequentially on the CRT monitor. All breast masses were enhanced after gadolinium and stood out as bright lesions on subtraction images. The tumor margin and its extension were more precisely evaluated on subtraction MR images than on conventional postcontrast MR images. Breast cancer showed a characteristic time-intensity curve with an early peak, in contrast to fibroadenoma, which showed a gradual increase in signal intensity. Subtraction MR imaging is a simple method for the evaluation of breast masses, and further, the time-intensity curve obtained by dynamic study is helpful in the differential diagnosis of lesions. (author).

  18. The AAPM/RSNA physics tutorial for residents: digital fluoroscopy.

    Science.gov (United States)

    Pooley, R A; McKinney, J M; Miller, D A

    2001-01-01

    A digital fluoroscopy system is most commonly configured as a conventional fluoroscopy system (tube, table, image intensifier, video system) in which the analog video signal is converted to and stored as digital data. Other methods of acquiring the digital data (eg, digital or charge-coupled device video and flat-panel detectors) will become more prevalent in the future. Fundamental concepts related to digital imaging in general include binary numbers, pixels, and gray levels. Digital image data allow the convenient use of several image processing techniques including last image hold, gray-scale processing, temporal frame averaging, and edge enhancement. Real-time subtraction of digital fluoroscopic images after injection of contrast material has led to widespread use of digital subtraction angiography (DSA). Additional image processing techniques used with DSA include road mapping, image fade, mask pixel shift, frame summation, and vessel size measurement. Peripheral angiography performed with an automatic moving table allows imaging of the peripheral vasculature with a single contrast material injection.

  19. Influence of abutment tooth geometry on the accuracy of conventional and digital methods of obtaining dental impressions.

    Science.gov (United States)

    Carbajal Mejía, Jeison B; Wakabayashi, Kazumichi; Nakamura, Takashi; Yatani, Hirofumi

    2017-09-01

    Direct (intraoral) and indirect (desktop) digital scanning can record abutment tooth preparations despite their geometry. However, little peer-reviewed information is available regarding the influence of abutment tooth geometry on the accuracy of digital methods of obtaining dental impressions. The purpose of this in vitro study was to evaluate the influence of abutment tooth geometry on the accuracy of conventional and digital methods of obtaining dental impressions in terms of trueness and precision. Crown preparations with known total occlusal convergence (TOC) angles (-8, -6, -4, 0, 4, 8, 12, 16, and 22 degrees) were digitally created from a maxillary left central incisor and printed in acrylic resin. Each of these 9 reference models was scanned with a highly accurate reference scanner and saved in standard tessellation language (STL) format. Then, 5 conventional polyvinyl siloxane (PVS) impressions were made from each reference model, which was poured with Type IV dental stone scanned using both the reference scanner (group PVS) and the desktop scanner and exported as STL files. Additionally, direct digital impressions (intraoral group) of the reference models were made, and the STL files were exported. The STL files from the impressions obtained were compared with the original geometry of the reference model (trueness) and within each test group (precision). Data were analyzed using 2-way ANOVA with the post hoc least significant difference test (α=.05). Overall trueness values were 19.1 μm (intraoral scanner group), 23.5 μm (desktop group), and 26.2 μm (PVS group), whereas overall precision values were 11.9 μm (intraoral), 18.0 μm (PVS), and 20.7 μm (desktop). Simple main effects analysis showed that impressions made with the intraoral scanner were significantly more accurate than those of the PVS and desktop groups when the TOC angle was less than 8 degrees (Pgeometry. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry

  20. A randomised trial of screening with digital breast tomosynthesis plus conventional digital 2D mammography versus 2D mammography alone in younger higher risk women.

    Science.gov (United States)

    Maxwell, Anthony J; Michell, Michael; Lim, Yit Y; Astley, Susan M; Wilson, Mary; Hurley, Emma; Evans, D Gareth; Howell, Anthony; Iqbal, Asif; Kotre, John; Duffy, Stephen; Morris, Julie

    2017-06-30

    Digital breast tomosynthesis (DBT) has been shown to increase invasive cancer detection rates at screening compared to full field digital (2D) mammography alone, and some studies have reported a reduction in the screening recall rate. No prospective randomised studies of DBT have previously been published. This study compares recall rates with 2D mammography with and without concurrent DBT in women in their forties with a family history of breast cancer undergoing incident screening. Asymptomatic women aged 40-49 who had previously undergone mammography for an increased risk of breast cancer were recruited in two screening centres. Participants were randomised to screening with 2D mammography only at the first study screen followed a year later by screening with 2D plus DBT, or vice versa. Recall rates were compared using an intention to treat analysis. Reading performance was analysed for the larger centre. 1227 women were recruited. 1221 first screens (604 2D, 617 2D+DBT) and 1124second screens (558 2D+DBT, 566 2D) were analysed. Eleven women had screen-detected cancers: 5 after 2D, 6 after 2D+DBT. The false positive recall rates were 2.4% for 2D and 2.2% for 2D+DBT (p=0.89). There was a significantly greater reduction between rounds in the number of women with abnormal reads who were not recalled after consensus/arbitration with 2D+DBT than 2D (p=0.023). The addition of DBT to 2D mammography in incident screening did not lead to a significant reduction in recall rate. DBT may increase reader uncertainty until DBT screening experience is acquired. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. 胸部双能量减影摄影对气胸的诊断价值%The value of dual-energy subtraction with direct digital radiography in diagnosis of pneumothorax

    Institute of Scientific and Technical Information of China (English)

    赵钊; 陈立鹏; 王秀河; 黄力; 刘文华

    2012-01-01

    目的 探讨双能量减影摄片技术对气胸的诊断价值.方法 收集在本院行双能量胸部摄影,经CT检查证实为气胸的42例患者,由1位高年资放射科医师及1位高年资胸外科医生共同阅片,对其标准数字化摄影(DR)图像与双能量数字减影(DES)软组织图像进行分析,评价两者对气胸的显示情况.结果 对于大、中量气胸(13例,肺压缩≥20%),标准DR图像及DES软组织图像均能清楚显示(100%),但对于少量气胸(肺压缩<20%),尤其肺压缩边缘与肋骨、锁骨、肩胛骨重叠者,DES软组织图像比标准DR图像检出率更高,对肺压缩边缘的显示更清晰,差异有统计学意义.结论 双能量减影摄片技术能提高气胸的诊断率,降低漏诊率,是对DR图像诊断气胸的有效补充.%Objective To evaluate the ability of DR dual-energy subtraction(DES) in diagnosing pneumothorax.Methods 42 patients with pneumothorax confirmed by CT underwent dual-energy subtraction radiography of the chest in our hospital.The chest films were analysed by one senior radiologist and one surgeon.The detection of pneumothorax was evaluated with both DR and DES.Results The magnanimous or moderately pneumothorax (13 cases,pulmonary compression≥20% (could be detected by DR images and DES soft tissue images (100%) ,but for slight pneumothorax (pulmonary compression<20% ) , especially when pneumothorax line overlap with costa,clavicle and scapula,DES soft tissue images could detect it more sensitively than regular DR images,and the pneumothorax lines were showed more clearly, there was statistical difference between these two images.Conclusion Dual-energy subtraction technique is superior to regular DR images in showing the pneumothorax line,so it can improve the diagnosis of pneumothorax and reduce the rate of misdiagnosis.Dual energy subtraction images can act as an effective complement for the original DR images in diagnosing pneumothorax.

  2. Review and comparison of non-conventional imaging systems for three-dimensional digitization of transparent objects

    Science.gov (United States)

    Mériaudeau, Fabrice; Rantoson, Rindra; Fofi, David; Stolz, Christophe

    2012-04-01

    Fashion and design greatly influence the conception of manufactured products which now exhibit complex forms and shapes. Two-dimensional quality control procedures (e.g., shape, textures, colors, and 2D geometry) are progressively being replaced by 3D inspection methods (e.g., 3D geometry, colors, and texture on the 3D shape) therefore requiring a digitization of the object surface. Three dimensional surface acquisition is a topic which has been studied to a large extent, and a significant number of techniques for acquiring 3D shapes has been proposed, leading to a wide range of commercial solutions available on the market. These systems cover a wide range from micro-scale objects such as shape from focus and shape from defocus techniques, to several meter sized objects (time of flight technique). Nevertheless, the use of such systems still encounters difficulties when dealing with non-diffuse (non Lambertian) surfaces as is the case for transparent, semi-transparent, or highly reflective materials (e.g., glass, crystals, plastics, and shiny metals). We review and compare various systems and approaches which were recently developed for 3D digitization of transparent objects.

  3. Dual-energy subtraction radiography of the breast

    Energy Technology Data Exchange (ETDEWEB)

    Asaga, Taro; Masuzawa, Chihiro; Kawahara, Satoru; Motohashi, Hisahiko; Okamoto, Takashi; Tamura, Nobuo

    1988-06-01

    Dual-energy projection radiography was applied to breast examination. To perform the dual-energy subtraction radiography using a digital radiography unit, high and low-energy exposures were made at an appropriate time interval under differing X-ray exposure conditions. Dual-energy subtraction radiography was performed in 41 cancer patients in whom the tumor shadow was equivocal or the border of cancer infiltration was not clearly demonstrated by compression mammography, and 15 patients with benign diseases such as fibrocystic disease, cyst and fibroadenoma. In 21 cases out of the 41 cancer patients, the dual-energy subtraction radiography clearly visualized the malignant tumor shadows and the border of cancer infiltration and the daughter nodules by removing the shadows of normal mammary gland. On the other hand, beign diseases such as fibrocystic disease and cyst could be diagnosed as such, because the tumor shadow and the irregularly concentrated image of mammary gland disappeared by the dual-energy subtraction. These results suggest that this new technique will be useful in examination of breast masses.

  4. Subtraction Radiography for the Diagnosis of Bone Lesions in Dogs.

    Science.gov (United States)

    1984-05-31

    Avail ander Journal of Periodontology Dist Special Ř 211 East Chicago Avenue Room 924 Chicago, IL 60611 Dear Sirs: I m submitting an original...research article titled "Subtraction Radiography for the Diagnosis of Bone Lesions in Dogs" solely to the Journal of Periodontology for review and... clinical practice in our area. 60-70 Kvp would have produced more contrast in the radiographic films used for the conventional technique, but likely

  5. Gd-enhanced subtraction MR venography

    Energy Technology Data Exchange (ETDEWEB)

    Hoshi, Toshiko; Hachiya, Takashi; Kanauchi, Tetsu; Hando, Yumiko; Homma, Tsuguo [Saitama Cardiovascular and Respiratory Center, Konan (Japan)

    1999-10-01

    We succeeded in distinctly imaging the calf veins using Gd-enhanced subtraction MR venography (Gd SMRV). Gd SMRV was performed in 15 normal legs, 33 varicose legs and 22 legs with suspected deep venous thrombosis. Conventional venography was performed in 46 legs in all. The deep veins of the calf, greater saphenous vein, and intramuscular veins had high rates of demonstration in normal legs and varicose legs (84, 100%, 87, 97%, 67, 73%). The varices were also well demonstrated (100%). When Gd SMRV was compared with conventional venography in terms of diagnosis of calf venous thrombosis, the sensitivity of this method was 100%, specificity was 92% and accuracy was 93%. We found high intensity thrombi on precontrast images in most cases, a finding that was important for the diagnosis of local thrombi. This method was non-invasive and was able to clearly visualize veins in the calf. We concluded that Gd SMRV was useful for calf venous disease, especially calf venous thrombosis. (author)

  6. Radiography of scoliosis: comparative dosimetry between conventional technique and digital fluorography; Radiographie des scolioses: dosimetrie comparee entre la technique conventionnelle et la fluorographie numerique

    Energy Technology Data Exchange (ETDEWEB)

    Gorincour, G.; Paris, M.; Aschero, A.; Bourliere, B.; Devred, P.; Petit, P. [Hopital Timone-Enfants, Service de Radiologie Pediatrique, 13 - Marseille (France); Barrau, K.; Auquier, P. [Faculte de Medecine de Marseille, Service de Sante Publique, 13 - Marseille (France); Waultier, S.; Bourrelly, M.; Mundler, O. [Hopital Timone-Enfants, Service de Medecine Nucleaire, 13 - Marseille (France); Viehweger, E.; Jouve, J.L.; Bollini, G. [Hopital Timone-Enfants, Service de Chirurgie Orthopedique, 13 - Marseille (France)

    2007-03-15

    Objective. Compare the irradiation delivered in conventional radiography and digital radiography by image intensifier during a scoliosis workup. Patients and Methods. Our prospective randomized study included 105 patients, all of whom were identified according to socio-demographic parameters as well as criteria evaluating the quality of the full front spinal x-ray at PA incidence. The entry dose at the scapula and the exit dose in inter-orbital, thyroid, mammary, and hypo-gastric projection was measured by thermoluminescent dosimeters. Results. The results of 71 girls and 28 boys, aged a mean 13.8 years with a mean weight of 47 kg were analyzed. At equal image quality, the entry dose was not significantly different between the two techniques; the mean exit dose reduction was 64% during digital acquisition. This reduction involved the inter-orbital (162%), mammary (43%), and thyroid (309%) regions. However, this system is more irradiating in the hypo-gastric region (34%). Conclusion. The dosimetric evaluation of the different imaging techniques used to explore the entirety of the spine should be part of radiologists' quality standard used to document their work and their choices. (authors)

  7. Cutaneous Force Feedback as a Sensory Subtraction Technique in Haptics.

    Science.gov (United States)

    Prattichizzo, D; Pacchierotti, C; Rosati, G

    2012-01-01

    A novel sensory substitution technique is presented. Kinesthetic and cutaneous force feedback are substituted by cutaneous feedback (CF) only, provided by two wearable devices able to apply forces to the index finger and the thumb, while holding a handle during a teleoperation task. The force pattern, fed back to the user while using the cutaneous devices, is similar, in terms of intensity and area of application, to the cutaneous force pattern applied to the finger pad while interacting with a haptic device providing both cutaneous and kinesthetic force feedback. The pattern generated using the cutaneous devices can be thought as a subtraction between the complete haptic feedback (HF) and the kinesthetic part of it. For this reason, we refer to this approach as sensory subtraction instead of sensory substitution. A needle insertion scenario is considered to validate the approach. The haptic device is connected to a virtual environment simulating a needle insertion task. Experiments show that the perception of inserting a needle using the cutaneous-only force feedback is nearly indistinguishable from the one felt by the user while using both cutaneous and kinesthetic feedback. As most of the sensory substitution approaches, the proposed sensory subtraction technique also has the advantage of not suffering from stability issues of teleoperation systems due, for instance, to communication delays. Moreover, experiments show that the sensory subtraction technique outperforms sensory substitution with more conventional visual feedback (VF).

  8. Value of Subtraction in Fat-Saturated Three-Dimensional Contrast-Enhanced Magnetic Resonance Angiography of the Hemodialysis Fistula

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, N.; Sato, M.; Niitsu, M.; Saida, Y. [Univ. of Tsukuba Hospital, Ibaraki (Japan). Dept. of Radiology

    2004-10-01

    Purpose: To evaluate image subtraction in a three-dimensional contrast-enhanced magnetic resonance angiography (3D CE-MRA) using fat suppression for the hemodialysis fistula. Material and Methods: Fifteen patients suffering from hemodialysis fistula dysfunction were imaged with 3D CE-MRA using fat suppression and digital subtraction angiography (DSA). Non-subtracted and subtracted MRA images using maximum intensity projection (MIP) were constructed and the validity of the MRA interpretations of the degree of vascular stenoses was evaluated using DSA as the standard of reference. Image quality was assessed using qualitative analysis (vessel contrast) and quantitative analysis (contrast-to-noise ratio (CNR) of the vessel versus the background). Results: In the vessels with stenosis of 50% or greater, the sensitivity and specificity of the non-subtracted MRA were 89.5% and 81.8%, respectively, and of the subtracted MRA 89.5% and 86.4%, respectively. There was no significant difference in the detectability of stenoses between either MRA. The vessel contrast of the anterior interosseous artery and the CNR of the anterior interosseous artery versus the background on the subtracted MRA were significantly superior to those on the non-subtracted MRA. With regard to the radial artery and cephalic vein, there was no significant difference in the vessel contrast and CNR between either MRA. Conclusion: Both subtracted and non-subtracted MRA techniques are useful in detecting hemodialysis fistula dysfunction.

  9. Reference Linking with DOIs: A Case Study [and] The Santa Fe Convention of the Open Archives Initiative [and] The UPS Prototype: An Experiment End-User Service across E-Print Archives [and] The Costs of Print, Fiche, and Digital Access: The Early Canadiana Online Project [and] Ad*Access: Seeking Copyright Permissions for a Digital Age.

    Science.gov (United States)

    Atkins, Helen; Lyons, Catherine; Ratner, Howard; Risher, Carol; Shillum, Chris; Sidman, David; Stevens, Andrew; Van de Sompel, Herbert; Lagoze, Carl; Van de Sompel, Herbert; Krichel, Thomas; Nelson, Michael L.; Hochstenbach, Patrick; Lyapunov, Victor M.; Maly, Kurt; Zubair, Mohammad; Kholief, Mohamed; Liu, Xiaoming; O'Connell, Heath; Kingma, Bruce R.; Pritcher, Lynn

    2000-01-01

    Includes five articles that discuss publishers' metadata hyperlinks with Digital Object Identifiers (DOIs) on the Internet; the Santa Fe Convention of the Open Archives initiative (Oai) that promotes author self-archiving; the Universal Preprint Service; costs of digital, microfiche, and print access; and an online database of old print…

  10. Design of a Floating-Point Fused Add-Subtract Unit Using Verilog

    Directory of Open Access Journals (Sweden)

    Mayank Sharma,

    2013-06-01

    Full Text Available A floating-point (FP fused add-subtract unit is presented that performs simultaneous floating-point operation of add-subtract on a common pair of single-precision data at the same time that it takes to perform in a single addition with a conventional floating-point adder. The system was placed and routed in 45nm process so that there will be less consumption of memory as well as power.

  11. Eigenspectrum Noise Subtraction Methods in Lattice QCD

    CERN Document Server

    Guerrero, Victor; Wilcox, Walter

    2010-01-01

    We propose a new noise subtraction method, which we call "eigenspectrum subtraction", which uses low eigenmode information to suppress statistical noise at low quark mass. This is useful for lattice calculations involving disconnected loops or all-to-all propagators. It has significant advantages over perturbative subtraction methods. We compare unsubtracted, eigenspectrum and perturbative error bar results for the scalar operator on a small Wilson QCD matrix.

  12. New Noise Subtraction Methods in Lattice QCD

    CERN Document Server

    Baral, Suman; Morgan, Ronald B

    2016-01-01

    Noise subtraction techniques can help reduce the statistical uncertainty in the extraction of hard to detect signals. We describe new noise subtraction methods in Lattice QCD which apply to disconnected diagram evaluations. Some of the noise suppression techniques include polynomial quark matrix methods, eigenspectrum deflation methods, and combination methods. Our most promising technique combines polynomial and Hermitian deflation subtraction methods. The overall goal is to improve the efficiency of Lattice QCD noise method algorithms.

  13. Helping Students to Connect Subtraction Strategies Improves Mathematical Reasoning for Students and Teachers

    Science.gov (United States)

    Sci, Eve

    2011-01-01

    After administering an end of unit assessment written by the school's math program, teachers of three second grade classes in a New York City school noticed a majority of the students had not demonstrated mastery of subtracting two, two-digit numbers. The teachers worked with the school's math coach to implement an instructional unit that required…

  14. Temporal subtraction contrast-enhanced dedicated breast CT

    Science.gov (United States)

    Gazi, Peymon M.; Aminololama-Shakeri, Shadi; Yang, Kai; Boone, John M.

    2016-09-01

    The development of a framework of deformable image registration and segmentation for the purpose of temporal subtraction contrast-enhanced breast CT is described. An iterative histogram-based two-means clustering method was used for the segmentation. Dedicated breast CT images were segmented into background (air), adipose, fibroglandular and skin components. Fibroglandular tissue was classified as either normal or contrast-enhanced then divided into tiers for the purpose of categorizing degrees of contrast enhancement. A variant of the Demons deformable registration algorithm, intensity difference adaptive Demons (IDAD), was developed to correct for the large deformation forces that stemmed from contrast enhancement. In this application, the accuracy of the proposed method was evaluated in both mathematically-simulated and physically-acquired phantom images. Clinical usage and accuracy of the temporal subtraction framework was demonstrated using contrast-enhanced breast CT datasets from five patients. Registration performance was quantified using normalized cross correlation (NCC), symmetric uncertainty coefficient, normalized mutual information (NMI), mean square error (MSE) and target registration error (TRE). The proposed method outperformed conventional affine and other Demons variations in contrast enhanced breast CT image registration. In simulation studies, IDAD exhibited improvement in MSE (0-16%), NCC (0-6%), NMI (0-13%) and TRE (0-34%) compared to the conventional Demons approaches, depending on the size and intensity of the enhancing lesion. As lesion size and contrast enhancement levels increased, so did the improvement. The drop in the correlation between the pre- and post-contrast images for the largest enhancement levels in phantom studies is less than 1.2% (150 Hounsfield units). Registration error, measured by TRE, shows only submillimeter mismatches between the concordant anatomical target points in all patient studies. The algorithm was

  15. Accuracy of Cone Beam Computed Tomography, Photostimulable Phosphor Plate Digital Radiography and Conventional Radiography for Detection of Artificial Cancellous Bone Defects

    Directory of Open Access Journals (Sweden)

    Roghieh Bardal Bardal

    2016-08-01

    Full Text Available Objectives: The optimal goal of radiography is to provide high-quality diagnostic images with the least patient radiation dose. The aim of this study was to evaluate the accuracy of cone-beam computed tomography (CBCT and intraoral photostimulable phosphor plate (PSP digital and film-based conventional radiography for detection of artificial cancellous bone defects.Materials and Methods: Five dry human mandibles were used in this study. The mandibles were placed inside a water bath made of plexiglass plates; then PSP and CBCT scans were obtained. The mandibles were cut by a coping saw in buccolingual dimension and oval defects measuring 6.1×6.1 mm, 3×6.1 mm and 4×4 mm were created by a milling machine in the spongy bone. After fixing the two parts together (buccal and lingual, radiographs were repeated. Presence or absence of defects on images was evaluated and recorded by the two observers. Using SPSS 16, compatibility level, sensitivity, specificity and receiver operating curve (ROC analysis were determined for each observer.Results: The intraobserver agreement in all three imaging modalities was low to moderate (kappa≤0.613. The inter-observer agreement in all the three imaging modalities was moderate (kappa=0.406. The area under the curve (AUC of the imaging modalities in each observation was not significantly different. The area under the curve based on defect size for the two observers was not significantly different either.Conclusion: Defects confined to spongy bone can be identified on film and PSP radiographs and CBCT scans. However, interpretation of PSP images and CBCT scans needs greater expertise and skills.

  16. Polynomial Subtraction Method for Disconnected Quark Loops

    CERN Document Server

    Liu, Quan; Morgan, Ron

    2014-01-01

    The polynomial subtraction method, a new numerical approach for reducing the noise variance of Lattice QCD disconnected matrix elements calculation, is introduced in this paper. We use the MinRes polynomial expansion of the QCD matrix as the approximation to the matrix inverse and get a significant reduction in the variance calculation. We compare our results with that of the perturbative subtraction and find that the new strategy yields a faster decrease in variance which increases with quark mass.

  17. A Mathematical Model for Suppression Subtractive Hybridization

    OpenAIRE

    2002-01-01

    Suppression subtractive hybridization (SSH) is frequently used to unearth differentially expressed genes on a whole-genome scale. Its versatility is based on combining cDNA library subtraction and normalization, which allows the isolation of sequences of varying degrees of abundance and differential expression. SSH is a complex process with many adjustable parameters that affect the outcome of gene isolation.We present a mathematical model of SSH based on DNA hybridization kinetics for assess...

  18. Advanced nanopattern formation by a subtractive self-organization process with focused ion beams

    Energy Technology Data Exchange (ETDEWEB)

    Lugstein, A. [Technical University Vienna, Floragasse 7, 1040 Vienna (Austria)]. E-mail: alois.lugstein@tuwien.ac.at; Basner, B. [Technical University Vienna, Floragasse 7, 1040 Vienna (Austria); Brezna, W. [Technical University Vienna, Floragasse 7, 1040 Vienna (Austria); Weil, M. [Technical University Vienna, Floragasse 7, 1040 Vienna (Austria); Golka, S. [Technical University Vienna, Floragasse 7, 1040 Vienna (Austria); Bertagnolli, E. [Technical University Vienna, Floragasse 7, 1040 Vienna (Austria)

    2006-01-15

    We have studied the evolution of the GaAs, InAs and GaSb surfaces due to FIB exposure. In contrast to conventional bottom up or top down processes the observed nanopattern formation is discussed, based on a subtractive self-organization process relying on material decomposition induced by FIB exposure.

  19. Subtraction-multiphase-CT unbeneficial for early detection of colorectal liver metastases

    Energy Technology Data Exchange (ETDEWEB)

    Meijerink, Martijn R., E-mail: mr.meijerink@vumc.n [Department of Radiology, Vrije Universiteit Medisch Centrum, Amsterdam (Netherlands); Waesberghe, Jan Hein T.M. van; Golding, Richard P. [Department of Radiology, Vrije Universiteit Medisch Centrum, Amsterdam (Netherlands); Weide, Lineke van der [Master of Oncology Program, Vrije Universiteit Medisch Centrum, Amsterdam (Netherlands); Tol, Petrousjka van den [Department of Surgical Oncology, Vrije Universiteit Medisch Centrum, Amsterdam (Netherlands); Meijer, Sybren [Master of Oncology Program, Vrije Universiteit Medisch Centrum, Amsterdam (Netherlands); Kuijk, Cornelis van [Department of Radiology, Vrije Universiteit Medisch Centrum, Amsterdam (Netherlands)

    2010-06-15

    Purpose: To assess the value of multiphase-subtraction-CT for early detection of colorectal-liver-metastases (CRLM). Methods and materials: In 50 patients suspected of CRLM a routine pre-operative 4-phase-CT-scan of the upper abdomen was obtained. All 12 possible image subtractions between two different phases were constructed applying 3D-image-registration to decrease distortion artefacts induced by differences in inspiration volume. Two experienced radiologists initially reviewed the conventional 4-phase-CT for malignant and/or benign appearing lesions and at least 1-month hereafter the same 4-phase-CT now including the subtracted images. The results were compared to histology reports or to a combination of surgical exploration and intraoperative ultrasound together with results from pre-operative PET and follow-up examinations. Results: Although an additional number of 31 malignant appearing lesions were detected on the subtraction images, none proved to represent a true CRLM. Interobserver agreement ({kappa}) decreased from 0.627 (good) to 0.418 (fair). Conclusion: Adding linearly co-registered subtraction-CT images to a conventional 4-phase-CT protocol does not improve detection of CRLM.

  20. Enhanced image reconstruction of three-dimensional fluorescent assays by subtractive structured-light illumination microscopy.

    Science.gov (United States)

    Choi, Jong-ryul; Kim, Donghyun

    2012-10-01

    We investigate improved image reconstruction of structured light illumination for high-resolution imaging of three-dimensional (3D) cell-based assays. For proof of concept, an in situ fluorescence optical detection system was built with a digital micromirror device as a spatial light modulator, for which phase and tilting angle in a grid pattern were varied to implement specific image reconstruction schemes. Subtractive reconstruction algorithms based on structured light illumination were used to acquire images of fluorescent microbeads deposited as a two-dimensional monolayer or in 3D alginate matrix. We have confirmed that an optical subtraction algorithm improves axial and lateral resolution by effectively removing out-of-focus fluorescence. The results suggest that subtractive image reconstruction can be useful for structured illumination microscopy of broad types of cell-based assays with high image resolution.

  1. Dental arch relationships on three-dimensional digital study models and conventional plaster study models for patients with unilateral cleft lip and palate.

    Science.gov (United States)

    Asquith, J A; McIntyre, G T

    2012-09-01

    To determine if three-dimensional (3D) digital study models could replace plaster study models for the evaluation of dental arch relationships for patients with unilateral cleft lip and palate. Observational study involving plaster study models from a records archive. U.K. National Health Service. Thirty sets of study models of 5-year-old patients with unilateral cleft lip and palate were identified and scanned to produce 3D digital study models by ESM Digital Solutions Ltd. (Swords, Co. Dublin, Ireland) using an R250 Orthodontic Study Model Scanner (3Shape A/S, Copenhagen, Denmark). None. The plaster and 3D digital study models were scored using the 5-year-olds' and modified Huddart Bodenham indices and analyzed using the Friedman test (p plaster and 3D digital models. Intra-observer and interobserver reproducibility were good (0.62 to 0.83 and 0.64 to 0.78, respectively). There were no statistically significant differences between the scores for the 3D digital study models when compared to the plaster study models for either the 5-year-olds' index (p  =  .12) or for the modified Huddart Bodenham index (p  =  .506). Three-dimensional digital models are a valid alternative to traditional plaster study models for the evaluation of dental arch relationships in patients with unilateral cleft lip and palate.

  2. The Spectrum of Static Subtracted Geometries

    CERN Document Server

    Andrade, Tomas; Cohen-Maldonado, Diego

    2016-01-01

    Subtracted geometries are black hole solutions of the four dimensional STU model with rather interesting ties to asymptotically flat black holes. In addition, a peculiar feature is that the solutions to the Klein-Gordon equation on this subtracted background can be organized according to representations of the conformal group $SO(2,2)$. We test if this behavior persists for the linearized fluctuations of gravitational and matter fields on static, electrically charged backgrounds of this kind. We find that there is a subsector of the modes that do display conformal symmetry, while some modes do not. We also discuss two different effective actions that describe these subtracted geometries and how the spectrum of quasinormal modes is dramatically different depending upon the action used.

  3. Subtraction Radiographic Assessment of Underlying Dentin After Partial Carious Dentin Removal in Primary Teeth.

    Science.gov (United States)

    Phonghanyudh, Araya; Ruangdit, Chayathorn; Pornprasertsuk-D Amrongsri, Suchaya; Phanthumvanit, Prathip

    2017-09-21

    To assess the one-year outcome of glass-ionomer cement (GIC) restorations with partial carious dentin removal in primary molars using digital subtraction radiographs. Children ages 6-8 years were recruited. Forty-nine primary molars with deep carious lesions were studied. The carious dentin was removed at the dentoenamel junction (DEJ) and restored with GIC. Digital radiographs were taken immediately after restoration, and at 6 and 12 months after restoration. The sets of digital radiographs were subtracted and analysed using Image-Pro Plus software. At the 12-month follow-up, 38 of the original 49 primary molars were analysed. No postoperative pain or signs of pulp pathology were reported. 76% and 87% of molars showed an increase in density of the studied areas compared to control areas at 6- and 12- month follow-ups, respectively. The density of digital subtraction radiographs increased to 5.3 and 8.2 at 6 and 12 months from baseline, respectively. The mean density of the areas under restoration at 6 months and 12 months was statistically significantly higher than at baseline (paired t-test; p carious dentin removal in primary molars showed a high potential for dentin remineralisation after 1 year.

  4. Probabilistic Model-Based Background Subtraction

    DEFF Research Database (Denmark)

    Krüger, Volker; Andersen, Jakob; Prehn, Thomas

    2005-01-01

    manner. Bayesian propagation over time is used for proper model selection and tracking during model-based background subtraction. Bayes propagation is attractive in our application as it allows to deal with uncertainties during tracking. We have tested our approach on suitable outdoor video data....... is the correlation between pixels. In this paper we introduce a model-based background subtraction approach which facilitates prior knowledge of pixel correlations for clearer and better results. Model knowledge is being learned from good training video data, the data is stored for fast access in a hierarchical...

  5. Construction of Differential-Methylation Subtractive Library

    Directory of Open Access Journals (Sweden)

    Wei Hu

    2014-01-01

    Full Text Available Stress-induced ROS changes DNA methylation patterns. A protocol combining methylation-sensitive restriction endonuclease (MS-RE digestion with suppression subtractive hybridization (SSH to construct the differential-methylation subtractive library was developed for finding genes regulated by methylation mechanism under cold stress. The total efficiency of target fragment detection was 74.64%. DNA methylation analysis demonstrated the methylation status of target fragments changed after low temperature or DNA methyltransferase inhibitor treatment. Transcription level analysis indicated that demethylation of DNA promotes gene expression level. The results proved that our protocol was reliable and efficient to obtain gene fragments in differential-methylation status.

  6. Renormalizing the NN interaction with multiple subtractions

    Energy Technology Data Exchange (ETDEWEB)

    Timoteo, V.S. [Faculdade de Tecnologia, Universidade Estadual de Campinas, 13484-332 Limeira, SP (Brazil); Frederico, T. [Instituto Tecnologico de Aeronautica, Comando de Tecnologia Aeroespacial, 12228-900 Sao Jose dos Campos, SP (Brazil); Delfino, A. [Departamento de Fisica, Universidade Federal Fluminense, 24210-150 Niteroi, RJ (Brazil); Tomio, L. [Instituto de Fisica Teorica, Universidade Estadual Paulista, 01140-070 Sao Paulo, SP (Brazil); Szpigel, S.; Duraes, F.O. [Centro de Ciencias e Humanidades, Universidade Presbiteriana Mackenzie, 01302-907 Sao Paulo, SP (Brazil)

    2010-02-15

    The aim of this work is to show how to renormalize the nucleon-nucleon interaction at next-to-next-to-leading order using a systematic subtractive renormalization approach with multiple subtractions. As an example, we calculate the phase shifts for the partial waves with total angular momentum J=2. The intermediate driving terms at each recursive step as well as the renormalized T-matrix are also shown. We conclude that our method is reliable for singular potentials such as the two-pion exchange and derivative contact interactions.

  7. Removal of power-line interference from the ECG: a review of the subtraction procedure

    Directory of Open Access Journals (Sweden)

    Christov Ivaylo

    2005-08-01

    Full Text Available Abstract Background Modern biomedical amplifiers have a very high common mode rejection ratio. Nevertheless, recordings are often contaminated by residual power-line interference. Traditional analogue and digital filters are known to suppress ECG components near to the power-line frequency. Different types of digital notch filters are widely used despite their inherent contradiction: tolerable signal distortion needs a narrow frequency band, which leads to ineffective filtering in cases of larger frequency deviation of the interference. Adaptive filtering introduces unacceptable transient response time, especially after steep and large QRS complexes. Other available techniques such as Fourier transform do not work in real time. The subtraction procedure is found to cope better with this problem. Method The subtraction procedure was developed some two decades ago, and almost totally eliminates power-line interference from the ECG signal. This procedure does not affect the signal frequency components around the interfering frequency. Digital filtering is applied on linear segments of the signal to remove the interference components. These interference components are stored and further subtracted from the signal wherever non-linear segments are encountered. Results Modifications of the subtraction procedure have been used in thousands of ECG instruments and computer-aided systems. Other work has extended this procedure to almost all possible cases of sampling rate and interference frequency variation. Improved structure of the on-line procedure has worked successfully regardless of the multiplicity between the sampling rate and the interference frequency. Such flexibility is due to the use of specific filter modules. Conclusion The subtraction procedure has largely proved advantageous over other methods for power-line interference cancellation in ECG signals.

  8. Spectral Subtraction Approach for Interference Reduction of MIMO Channel Wireless Systems

    Directory of Open Access Journals (Sweden)

    Tomohiro Ono

    2005-08-01

    Full Text Available In this paper, a generalized spectral subtraction approach for reducing additive impulsive noise, narrowband signals, white Gaussian noise and DS-CDMA interferences in MIMO channel DS-CDMA wireless communication systems is investigated. The interference noise reduction or suppression is essential problem in wireless mobile communication systems to improve the quality of communication. The spectrum subtraction scheme is applied to the interference noise reduction problems for noisy MIMO channel systems. The interferences in space and time domain signals can effectively be suppressed by selecting threshold values, and the computational load with the FFT is not large. Further, the fading effects of channel are compensated by spectral modification with the spectral subtraction process. In the simulations, the effectiveness of the proposed methods for the MIMO channel DS-CDMA is shown to compare with the conventional MIMO channel DS-CDMA.

  9. Detecting cerebral vascular diseases by transcranial Doppler ultrasound and dolor Doppler flow imaging in comparison with digital subtracted angiography%经颅多普勒及彩色多普勒超声与数字减影脑血管造影对脑血管病检测的比较研究

    Institute of Scientific and Technical Information of China (English)

    张小征; 吕健; 李俊; 胡军民; 龚杰; 徐国政; 马廉亭; 陈欣林

    2000-01-01

    目的 评价经颅多普勒(TCD)在脑血管病诊断、疗效评估中的应用价值.方法 应用TCD检测脑血管疾病患者306例,其中脑动静脉畸形170例,颈动脉海绵窦瘘(CCF)69例,颅内动脉瘤67例,并与数字减影脑血管造影(DSA)、彩色多普勒血流显像(CDFI)进行对比研究.结果 以DSA脑血管造影为金指标,TCD检出脑动静脉畸形93%,检出CCF 100%,判断CCF静脉回流方式96%,检出颅内动脉瘤67%.对颅内较大动脉瘤(>1.5 cm)的检测有特征性表现,提出"动脉瘤样频谱"的新概念.结论 TCD能实时、准确反映颅内血流动力学改变及侧支循环代偿情况,对脑血管病诊断、疗效评估有重要价值.%Objective To evaluate the effect of transcranial Doppler(TCD)on detecting cerebral vascular diseases.Methods One hundred and seventy patients with cerebral arterovenous malformation(AVM),69 carotid cavernous fistula (CCF)and 67 intracranial aneurysms were examined early or late by TCD, digital subtracted angiography(DSA)and color Dopplor flow imaging.The results of their examination were compared and analyzed.Results If the results of DSA examination was regarded as a golden criterion of diagnosing the cerebral vascular dNease,93%of the 170 patients with AVMs,100% of the 69 patients with CCFS and 67%of the 67 patients with the aneurysms were detected by TCD respectively.It was found that the relative larger aneurysm(diameter>1.5 crn)had a special TCD manifestation, the SO-called ”aneurysm-like spectrum”. Conclusion TCD is necessary for detecting the cerebral vascular lesions because it can reveal accurately a change in the intracranial hemodynamics and a condition of the collateral circulation.

  10. Follow-up of intracranial aneurysms treated by flow diverter: comparison of three-dimensional time-of-flight MR angiography (3D-TOF-MRA) and contrast-enhanced MR angiography (CE-MRA) sequences with digital subtraction angiography as the gold standard.

    Science.gov (United States)

    Attali, Jonathan; Benaissa, Azzedine; Soize, Sébastien; Kadziolka, Krzysztof; Portefaix, Christophe; Pierot, Laurent

    2016-01-01

    Follow-up of intracranial aneurysms treated by flow diverter with MRI is complicated by imaging artifacts produced by these devices. This study compares the diagnostic accuracy of three-dimensional time-of-flight MR angiography (3D-TOF-MRA) and contrast-enhanced MRA (CE-MRA) at 3 T for the evaluation of aneurysm occlusion and parent artery patency after flow diversion treatment, with digital subtraction angiography (DSA) as the gold standard. Patients treated with flow diverters between January 2009 and January 2013 followed by MRA at 3 T (3D-TOF-MRA and CE-MRA) and DSA within a 48 h period were included in a prospective single-center study. Aneurysm occlusion was assessed with full and simplified Montreal scales and parent artery patency with three-grade and two-grade scales. Twenty-two patients harboring 23 treated aneurysms were included. Interobserver agreement using simplified scales for occlusion (Montreal) and parent artery patency were higher for DSA (0.88 and 0.61) and CE-MRA (0.74 and 0.55) than for 3D-TOF-MRA (0.51 and 0.02). Intermodality agreement was higher for CE-MRA (0.88 and 0.32) than for 3D-TOF-MRA (0.59 and 0.11). CE-MRA yielded better accuracy than 3D-TOF-MRA for aneurysm remnant detection (sensitivity 83% vs 50%; specificity 100% vs 100%) and for the status of the parent artery (specificity 63% vs 32%; sensitivity 100% vs 100%). At 3 T, CE-MRA is superior to 3D-TOF-MRA for the evaluation of aneurysm occlusion and parent artery patency after flow diversion treatment. However, intraluminal evaluation remains difficult with MRA regardless of the sequence used. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

  11. 多层螺旋CT对孤立性肠系膜上动脉夹层的诊断价值及与数字减影血管造影的对比分析%Comparison of diagnostic value between multislice CT and digital subtraction angiography in isolated supe-rior mesenteric artery dissection

    Institute of Scientific and Technical Information of China (English)

    张杨贵; 何旭升; 温志玲; 陈珊红; 高振华; 许俊丽

    2016-01-01

    目的:探讨64层螺旋CT血管成像及后处理技术对孤立性肠系膜上动脉夹层(SISMAD)的诊断价值,及与数字减影血管造影对比分析。方法回顾分析17例使用64层螺旋CT及数字减影血管造影(DSA)所发现的孤立性肠系膜上动脉夹层,结合横断位原始图像及各后处理方法重建图像,分析其影像征像。结果64层螺旋CT血管成像动脉期能清晰显示肠系膜上动脉及其低密度的内膜片,真假腔及破裂口显示良好,夹层累及范围,是否存在血栓及累及分支血管,术后追踪观察方便、准确。结论多层螺旋CT能清晰显示孤立性肠系膜上动脉夹层的病变特征,其检出率、并发症显示优于DSA,并能较好地指导DSA介入治疗及预后观察,是孤立性肠系膜上动脉夹层首选的无创检查方法。%Objective To compare the diagnostic value between 64-slice CT and digital subtraction angiogra-phy (DSA) in isolated superior mesenteric artery (SISMAD) dissection. Methods Retrospective study was taken in 17 patients with SMA Dissection, evidenced by both 64-slice CT and DSA,analyze the eikonic signs according to trans-verse view and reconstruction images. Results In artetial phase, multislice CT could clearly showed superior mesen-teric artery, its hypodense intimal orifice, true and false double lumen and oral cleft, intercalated bed range involved, with or without thrombus and lateral branch blood vessels could be indicated well, which had great convenience to follow-up postoperative. Conclusion Multislice CT, an atraumatic mothod for SMA dissection, could clearly present its pathological changes. It also has better detection rate and less complication compared with DAS. Moreover, multi-slice CT could help to direct treatment by DSA.

  12. Diagnosis of Subtraction Bugs Using Bayesian Networks

    Science.gov (United States)

    Lee, Jihyun; Corter, James E.

    2011-01-01

    Diagnosis of misconceptions or "bugs" in procedural skills is difficult because of their unstable nature. This study addresses this problem by proposing and evaluating a probability-based approach to the diagnosis of bugs in children's multicolumn subtraction performance using Bayesian networks. This approach assumes a causal network relating…

  13. Polygon Subtraction in 2 or 3 Dimensions

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, John E.

    2013-10-01

    When searching for computer code to perform the ubiquitous task of subtracting one polygon from another, it is difficult to find real examples and detailed explanations. This paper outlines the step-by-step process necessary to accomplish this basic task.

  14. Robust Background Subtraction with Incremental Eigen Models

    NARCIS (Netherlands)

    Gritti, T.

    2008-01-01

    In this report we first describe a background subtraction algorithm based on the use of eigen space decomposition. We then present a method to achive incremental modelling, which allows for faster computation and saving in memory requirements. We discuss the performanceof the algorithm and the issu

  15. Children's Understanding of Addition and Subtraction Concepts

    Science.gov (United States)

    Robinson, Katherine M.; Dube, Adam K.

    2009-01-01

    After the onset of formal schooling, little is known about the development of children's understanding of the arithmetic concepts of inversion and associativity. On problems of the form a+b-b (e.g., 3+26-26), if children understand the inversion concept (i.e., that addition and subtraction are inverse operations), then no calculations are needed…

  16. Video Background Subtraction in Complex Environments

    Directory of Open Access Journals (Sweden)

    Juana E. Santoyo-Morales

    2014-06-01

    Full Text Available Background subtraction models based on mixture of Gaussians have been extensively used for detecting objects in motion in a wide variety of computer vision applications. However, background subtraction modeling is still an open problem particularly in video scenes with drastic illumination changes and dynamic backgrounds (complex backgrounds. The purpose of the present work is focused on increasing the robustness of background subtraction models to complex environments. For this, we proposed the following enhancements: a redefine the model distribution parameters involved in the detection of moving objects (distribution weight, mean and variance, b improve pixel classification (background/foreground and variable update mechanism by a new time-space dependent learning-rate parameter, and c replace the pixel-based modeling currently used in the literature by a new space-time region-based model that eliminates the noise effect caused by drastic changes in illumination. Our proposed scheme can be implemented on any state of the art background subtraction scheme based on mixture of Gaussians to improve its resilient to complex backgrounds. Experimental results show excellent noise removal and object motion detection properties under complex environments.

  17. Rod strain after pedicle subtraction osteotomy

    DEFF Research Database (Denmark)

    Gehrchen, Poul Martin; Hallager, Dennis Winge; Dahl, Benny

    2016-01-01

    Pedicle subtraction osteotomy (PSO) can provide major sagittal correction for adult spinal deformity, sometimes achieving correction greater than 308. Surgeons have reported failure rates up to 30% within 2 years, increasing to 46% after 4 to 5 years (SDC Figure 1, http://links.lww.com/BRS/B87). ...

  18. Motion Tracking with Fast Adaptive Background Subtraction

    Institute of Scientific and Technical Information of China (English)

    Xiao; De-Gui; Yu; Sheng-sheng; 等

    2003-01-01

    To extract and track moving objects is usually one of the most important tasks of intelligent video surveillance systems. This paper presents a fast and adaptive background subtraction algorithm and the motion tracking process using this algorithm. The algorithm uses only luminance components of sampled image sequence pixels and models every pixel in a statistical model.The algorithm is characterized by its ability of real time detecting sudden lighting changes, and extracting and tracking motion objects faster. It is shown that our algorithm can be realized with lower time and space complexity and adjustable object detection error rate with comparison to other background subtraction algorithms. Making use of the algorithm, an indoor monitoring system is also worked out and the motion tracking process is presented in this paper.Experimental results testify the algorithms' good performances when used in an indoor monitoring system.

  19. Interferometry with Photon-Subtracted Thermal Light

    CERN Document Server

    Rafsanjani, Seyed Mohammad Hashemi; Magana-Loaiza, Omar S; Gard, Bryan T; Birrittella, Richard; Koltenbah, B E; Parazzoli, C G; Capron, Barbara A; Gerry, Christopher C; Dowling, Jonathan P; Boyd, Robert W

    2016-01-01

    We propose and implement a quantum procedure for enhancing the sensitivity with which one can determine the phase shift experienced by a weak light beam possessing thermal statistics in passing through an interferometer. Our procedure entails subtracting exactly one (which can be generalized to m) photons from the light field exiting an interferometer containing a phase-shifting element in one of its arms. As a consequence of the process of photon subtraction, and somewhat surprisingly, the mean photon number and signal-to-noise ratio of the resulting light field are thereby increased, leading to enhanced interferometry. This method can be used to increase measurement sensitivity in a variety of practical applications, including that of forming the image of an object illuminated only by weak thermal light.

  20. Moving object detection using background subtraction

    CERN Document Server

    Shaikh, Soharab Hossain; Chaki, Nabendu

    2014-01-01

    This Springer Brief presents a comprehensive survey of the existing methodologies of background subtraction methods. It presents a framework for quantitative performance evaluation of different approaches and summarizes the public databases available for research purposes. This well-known methodology has applications in moving object detection from video captured with a stationery camera, separating foreground and background objects and object classification and recognition. The authors identify common challenges faced by researchers including gradual or sudden illumination change, dynamic bac

  1. Blind foreground subtraction for intensity mapping experiments

    Science.gov (United States)

    Alonso, David; Bull, Philip; Ferreira, Pedro G.; Santos, Mário G.

    2015-02-01

    We make use of a large set of fast simulations of an intensity mapping experiment with characteristics similar to those expected of the Square Kilometre Array in order to study the viability and limits of blind foreground subtraction techniques. In particular, we consider three different approaches: polynomial fitting, principal component analysis (PCA) and independent component analysis (ICA). We review the motivations and algorithms for the three methods, and show that they can all be described, using the same mathematical framework, as different approaches to the blind source separation problem. We study the efficiency of foreground subtraction both in the angular and radial (frequency) directions, as well as the dependence of this efficiency on different instrumental and modelling parameters. For well-behaved foregrounds and instrumental effects, we find that foreground subtraction can be successful to a reasonable level on most scales of interest. We also quantify the effect that the cleaning has on the recovered signal and power spectra. Interestingly, we find that the three methods yield quantitatively similar results, with PCA and ICA being almost equivalent.

  2. Subtractive Structural Modification of Morpho Butterfly Wings.

    Science.gov (United States)

    Shen, Qingchen; He, Jiaqing; Ni, Mengtian; Song, Chengyi; Zhou, Lingye; Hu, Hang; Zhang, Ruoxi; Luo, Zhen; Wang, Ge; Tao, Peng; Deng, Tao; Shang, Wen

    2015-11-11

    Different from studies of butterfly wings through additive modification, this work for the first time studies the property change of butterfly wings through subtractive modification using oxygen plasma etching. The controlled modification of butterfly wings through such subtractive process results in gradual change of the optical properties, and helps the further understanding of structural optimization through natural evolution. The brilliant color of Morpho butterfly wings is originated from the hierarchical nanostructure on the wing scales. Such nanoarchitecture has attracted a lot of research effort, including the study of its optical properties, its potential use in sensing and infrared imaging, and also the use of such structure as template for the fabrication of high-performance photocatalytic materials. The controlled subtractive processes provide a new path to modify such nanoarchitecture and its optical property. Distinct from previous studies on the optical property of the Morpho wing structure, this study provides additional experimental evidence for the origination of the optical property of the natural butterfly wing scales. The study also offers a facile approach to generate new 3D nanostructures using butterfly wings as the templates and may lead to simpler structure models for large-scale man-made structures than those offered by original butterfly wings.

  3. Effect of color coding and subtraction on the accuracy of contrast echocardiography

    Science.gov (United States)

    Pasquet, A.; Greenberg, N.; Brunken, R.; Thomas, J. D.; Marwick, T. H.

    1999-01-01

    BACKGROUND: Contrast echocardiography may be used to assess myocardial perfusion. However, gray scale assessment of myocardial contrast echocardiography (MCE) is difficult because of variations in regional backscatter intensity, difficulties in distinguishing varying shades of gray, and artifacts or attenuation. We sought to determine whether the assessment of rest myocardial perfusion by MCE could be improved with subtraction and color coding. METHODS AND RESULTS: MCE was performed in 31 patients with previous myocardial infarction with a 2nd generation agent (NC100100, Nycomed AS), using harmonic triggered or continuous imaging and gain settings were kept constant throughout the study. Digitized images were post processed by subtraction of baseline from contrast data and colorized to reflect the intensity of myocardial contrast. Gray scale MCE alone, MCE images combined with baseline and subtracted colorized images were scored independently using a 16 segment model. The presence and severity of myocardial contrast abnormalities were compared with perfusion defined by rest MIBI-SPECT. Segments that were not visualized by continuous (17%) or triggered imaging (14%) after color processing were excluded from further analysis. The specificity of gray scale MCE alone (56%) or MCE combined with baseline 2D (47%) was significantly enhanced by subtraction and color coding (76%, pcolorized images (59%) was also significantly greater than gray scale MCE (43% and 29%, pcolor coding significantly improves the accuracy and specificity of MCE for detection of perfusion defects.

  4. Application of flat-panel digital subtraction angiography in interventional therapy for carotid cavernous fistutas:initial clinical experience%平板DSA新技术在介入治疗颈内动脉海绵窦瘘中应用初探

    Institute of Scientific and Technical Information of China (English)

    石强; 梁传声; 臧培卓; 徐克

    2009-01-01

    Objective To assess the clinical value offlat-panel digital subtraction angiography (DSA)in interventional therapy for carotid-cavemous fistula (CCF). Methods Three-dimensional (3D)DSA Was performed in 12 patients with CCF before the interventional therapy.The fistular orifice was located and measured with multiplanar reconstruction technique,and the Landscap roadmap of the fistula was obtained.Fistula embolization was performed according to the location of the fistular orifice and the surrounding bony marker indicated by 3D and Landscap roadmap. Results The fistular orifices were clearly displayed in the 12 patients with an average orifice diameter of 3.7 mm.The intemal carotid artery(ICA)and the bony marker of the cavernous sinus were shown simultaneously.Ten patients received endovascular embolization wiith detachable balloon, and 1 patient was treated wiith coil and 1 with stent placement.The ICA remained patent in 11 cases and carotid artery occlusion was performed in 1 case. Conclusion The 3D flat-panel DSA provides rich infolrmati,Ion on the fistular orifice,,and the bony markers can be identified by landscape roadmap technique..The combination of these two techniques guarantees effective and safe treatment of CCE.%目的 探讨平板DSA新技术在介入治疗颈内动脉海绵窦瘘(CCF)中的应用价值.方法 12例CCF患者术前行3DDSA检查,应用多平面重建技术定位瘘口并对瘘口进行测量.治疗中利用可调控实时透视路途技术(Landscap技术)制作路径图,以3D图像所示瘘口及周围骨性标志作为对照进行封堵治疗.结果 12例CCF均可清晰定位瘘口,瘘口直径平均3.7 mm.利用Landscap技术使颈内动脉路径及海绵窦骨性标志同时可见.球囊栓塞10例,弹簧圈栓塞1例,支架封堵瘘口1例.颈内动脉通畅11例,1例行颈内动脉闭塞.结论 平板DSA 3D技术提供了瘘口的丰富信息,Landscap技术为治疗增加了骨性标志,其联合应用为治疗CCF提供了安全保障.

  5. Comparison of contrast-enhanced MR angiography of the aortoiliac vessels using a 1.0 molar contrast agent at 1.0T with intra-arterial digital subtraction angiography; Ergebnisse der kontrastverstaerkten MR-Angiographie der aortoiliakalen Gefaesse mit einem 1-molaren Kontrastmittel bei 1,0 T; Vergleich zur i.a. DSA

    Energy Technology Data Exchange (ETDEWEB)

    Mohrs, O.K. [Klinik und Poliklinik fuer Radiologie, Johannes Gutenberg-Univ. Mainz (Germany); Cardioangiologisches Centrum Bethanien, Frankfurt/Main (Germany); Oberholzer, K.; Bernhard, S.; Kalden, P.; Thelen, M.; Kreitner, K.F. [Klinik und Poliklinik fuer Radiologie, Johannes Gutenberg-Univ. Mainz (Germany); Krummenauer, F. [Inst. fuer Med. Biometrie, Epidemiologie und Informatik, Johannes Gutenberg-Univ. Mainz (Germany); Neufang, A. [Klinik fuer Herz- und Thoraxchirurgie, Johannes Gutenberg-Univ. Mainz (Germany)

    2004-07-01

    Purpose: To evaluate the diagnostic accuracy of contrast-enhanced MR angiography (CE-MRA) using a 1.0 molar contrast agent at 1.0 T for the diagnosis of abdominal aortic aneurysms and stenoses of renal or iliac arteries in comparison to intraarterial digital subtraction angiography (DSA). Materials and Methods: A total of 19 patients with the suspicion of abdominal aortic aneurysm or stenosis of renal or iliac arteries were examined with CE-MRA at 1.0 T. Intra-arterial DAS served as reference in all cases. After test bolus tracking, 10 or 8 ml of the 1.0 molar contrast agent Gadobutrol corresponding to a dose of 0.1-0.15 mmol/kg bw were injected and imaging performed using a FLASH-3D sequence. To evaluate the interobserver-variability, the blinded images were analyzed by two radiologists. Besides the rating of overall image quality on a 4-point-scale, the images were evaluated for aneurysms and arteriosclerotic lesions with a stenosis of < 50% or > 50% or occlusion. Results: A total of 144 segments were analyzed. The mean value of the CE-MRA image quality was 3.4 on a 4-point scale. The sensitivity of CE-MRA in depicting relevant pathological findings was 96% and the specifity 99%. The positive predictive value was 96% and the negative predictive value 99%. Inter-observer variability was low with a kappa value of 0.82. Conclusion: CE-MRA using a 1.0 molar contrast agent at 1.0 Tenables an excellent diagnosis or exclusion of pathologies of the aortoiliac vessels. (orig.) [German] Ziel: Vergleich der MR-Angiographie (ce-MRA) der aortoiliakalen Gefaesse unter Verwendung eines 1-molaren, paramagnetischen Kontrastmittels bei 1,0 T zur intraarteriellen digitalen Subtraktionsangiographie (i.a. DSA). Material und Methoden: Es wurden 19 Patienten mit Verdacht auf ein infrarenales Aortenaneurysma bzw. eine Stenose der Nieren- oder Iliakalarterien untersucht. Die Messungen erfolgten bei 1,0 T unter Verwendung des 1-molaren, paramagnetischen Kontrastmittels Gadobutrol

  6. Rebranding Before the Digital Age: 4 Strategies Used by the Sheraton New York Hotel and Towers During the 1992 Democratic National Convention

    Directory of Open Access Journals (Sweden)

    Leora Halpern Lanz

    2016-05-01

    Full Text Available In 1992, New York City was undergoing a major revitalization in an effort to combat poverty and crime. The hospitality industry had much to contribute to these efforts like the Sheraton Centre Hotel. This hotel in particular was not only part of the city's drastic efforts to turn out its safety and public image, but it simultaneously leveraged its connection to the 1992 Democratic National Convention to lift its own rebrand.

  7. Evaluation of marginal and internal gaps of metal ceramic crowns obtained from conventional impressions and casting techniques with those obtained from digital techniques.

    Science.gov (United States)

    Rai, Rathika; Kumar, S Arun; Prabhu, R; Govindan, Ranjani Thillai; Tanveer, Faiz Mohamed

    2017-01-01

    Accuracy in fit of cast metal restoration has always remained as one of the primary factors in determining the success of the restoration. A well-fitting restoration needs to be accurate both along its margin and with regard to its internal surface. The aim of the study is to evaluate the marginal fit of metal ceramic crowns obtained by conventional inlay casting wax pattern using conventional impression with the metal ceramic crowns obtained by computer-aided design and computer-aided manufacturing (CAD/CAM) technique using direct and indirect optical scanning. This in vitro study on preformed custom-made stainless steel models with former assembly that resembles prepared tooth surfaces of standardized dimensions comprised three groups: the first group included ten samples of metal ceramic crowns fabricated with conventional technique, the second group included CAD/CAM-milled direct metal laser sintering (DMLS) crowns using indirect scanning, and the third group included DMLS crowns fabricated by direct scanning of the stainless steel model. The vertical marginal gap and the internal gap were evaluated with the stereomicroscope (Zoomstar 4); post hoc Turkey's test was used for statistical analysis. One-way analysis of variance method was used to compare the mean values. Metal ceramic crowns obtained from direct optical scanning showed the least marginal and internal gap when compared to the castings obtained from inlay casting wax and indirect optical scanning. Indirect and direct optical scanning had yielded results within clinically acceptable range.

  8. Digital printing

    Science.gov (United States)

    Sobotka, Werner K.

    1997-02-01

    Digital printing is described as a tool to replace conventional printing machines completely. Still this goal was not reached until now with any of the digital printing technologies to be described in the paper. Productivity and costs are still the main parameters and are not really solved until now. Quality in digital printing is no problem anymore. Definition of digital printing is to transfer digital datas directly on the paper surface. This step can be carried out directly or with the use of an intermediate image carrier. Keywords in digital printing are: computer- to-press; erasable image carrier; image carrier with memory. Digital printing is also the logical development of the new digital area as it is pointed out in Nicholas Negropotes book 'Being Digital' and also the answer to networking and Internet technologies. Creating images text and color in one country and publishing the datas in another country or continent is the main advantage. Printing on demand another big advantage and last but not least personalization the last big advantage. Costs and being able to coop with this new world of prepress technology is the biggest disadvantage. Therefore the very optimistic growth rates for the next few years are really nonexistent. The development of complete new markets is too slow and the replacing of old markets is too small.

  9. Evaluation of marginal and internal gaps of metal ceramic crowns obtained from conventional impressions and casting techniques with those obtained from digital techniques

    Directory of Open Access Journals (Sweden)

    Rathika Rai

    2017-01-01

    Full Text Available Background: Accuracy in fit of cast metal restoration has always remained as one of the primary factors in determining the success of the restoration. A well-fitting restoration needs to be accurate both along its margin and with regard to its internal surface. Aim: The aim of the study is to evaluate the marginal fit of metal ceramic crowns obtained by conventional inlay casting wax pattern using conventional impression with the metal ceramic crowns obtained by computer-aided design and computer-aided manufacturing (CAD/CAM technique using direct and indirect optical scanning. Materials and Methods: This in vitro study on preformed custom-made stainless steel models with former assembly that resembles prepared tooth surfaces of standardized dimensions comprised three groups: the first group included ten samples of metal ceramic crowns fabricated with conventional technique, the second group included CAD/CAM-milled direct metal laser sintering (DMLS crowns using indirect scanning, and the third group included DMLS crowns fabricated by direct scanning of the stainless steel model. The vertical marginal gap and the internal gap were evaluated with the stereomicroscope (Zoomstar 4; post hoc Turkey's test was used for statistical analysis. One-way analysis of variance method was used to compare the mean values. Results and Conclusion: Metal ceramic crowns obtained from direct optical scanning showed the least marginal and internal gap when compared to the castings obtained from inlay casting wax and indirect optical scanning. Indirect and direct optical scanning had yielded results within clinically acceptable range.

  10. Dual-Energy Subtraction Imaging for Diagnosing Vocal Cord Paralysis with Flat Panel Detector Radiography

    Energy Technology Data Exchange (ETDEWEB)

    Machida, Haruhiko; Yoda, Keiko; Arai, Yasuko [Tokyo Women' s Medical University Medical Center East, Tokyo (Japan)] (and others)

    2010-06-15

    To investigate the clinical feasibility of dual energy subtraction (DES) imaging to improve the delineation of the vocal cord and diagnostic accuracy of vocal cord paralysis as compared with the anterior-posterior view of flat panel detector (FPD) neck radiography. For 122 consecutive patients who underwent both a flexible laryngoscopy and conventional/DES FPD radiography, three blinded readers retrospectively graded the radiographs during phonation and inspiration on a scale of 1 (poor) to 5 (excellent) for the delineation of the vocal cord, and in consensus, reviewed the diagnostic accuracy of vocal cord paralysis employing the laryngoscopy as the reference. We compared vocal cord delineation scores and accuracy of vocal cord paralysis diagnosis by both conventional and DES techniques using ({kappa}statistics and assessing the area under the receiver operating characteristic curve (AUC). Vocal cord delineation scores by DES (mean, 4.2 {+-} 0.4) were significantly higher than those by conventional imaging (mean, 3.3 {+-} 0.5) (p < 0.0001). Sensitivity for diagnosing vocal cord paralysis by the conventional technique was 25%, whereas the specificity was 94%. Sensitivity by DES was 75%, whereas the specificity was 96%. The diagnostic accuracy by DES was significantly superior (({kappa}= 0.60, AUC = 0.909) to that by conventional technique ({kappa}= 0.18, AUC = 0.852) (p = 0.038). Dual energy subtraction is a superior method compared to the conventional FPD radiography for delineating the vocal cord and accurately diagnosing vocal cord paralysis.

  11. 传统X线机的医学影像数字化实现%Implement of Digitizing for Medical Image in Conventional X-ray Machine

    Institute of Scientific and Technical Information of China (English)

    丁兆国; 许陇云

    2004-01-01

    基于DICOM3.0标准,系统地分析了标准中关于X线医学图像的文件格式及网络通信过程,根据传统影像增强-电视系统X线机的数字化特点,设计了一种符合DICOM标准的医学X线图像采集、增强、传输与存储系统,着重介绍了DCM文件的存储、网络传输并给出了软件实现,为传统X线机融入PACS提供了一种方法.%DICOM file format for X-ray medical image and communication process are first analyzed . An X-ray medical image acquisition, transmission and storage system, which is compatible with DICOM standard, is then designed according to the characteristic of conventional X-ray machine using image intensifier-TV system. The file storage for DCM-format and network communication are introduced in detail and software model is given. A feasible technique for conventional X-ray machine integrating into PACS is proposed.

  12. Theoretical Analysis of Amounts of Musical Noise and Speech Distortion in Structure-Generalized Parametric Blind Spatial Subtraction Array

    Science.gov (United States)

    Miyazaki, Ryoichi; Saruwatari, Hiroshi; Shikano, Kiyohiro

    We propose a structure-generalized blind spatial subtraction array (BSSA), and the theoretical analysis of the amounts of musical noise and speech distortion. The structure of BSSA should be selected according to the application, i.e., a channelwise BSSA is recommended for listening but a conventional BSSA is suitable for speech recognition.

  13. Bone images from dual-energy subtraction chest radiography in the detection of rib fractures

    Energy Technology Data Exchange (ETDEWEB)

    Szucs-Farkas, Zsolt, E-mail: zsolt.szuecs@insel.ch [Department of Diagnostic, Interventional and Pediatric Radiology, University Hospital Bern, Freiburgstrasse 4, Bern CH-3010 (Switzerland); Lautenschlager, Katrin, E-mail: katrin@students.unibe.ch [Department of Diagnostic, Interventional and Pediatric Radiology, University Hospital Bern, Freiburgstrasse 4, Bern CH-3010 (Switzerland); Flach, Patricia M., E-mail: patricia.flach@irm.unibe.ch [Institute of Forensic Medicine, University of Bern, Freiburgstrasse 4, Bern CH-3010 (Switzerland); Ott, Daniel, E-mail: daniel.ott@insel.ch [Department of Diagnostic, Interventional and Pediatric Radiology, University Hospital Bern, Freiburgstrasse 4, Bern CH-3010 (Switzerland); Strautz, Tamara, E-mail: tamara.strautz@insel.ch [Department of Diagnostic, Interventional and Pediatric Radiology, University Hospital Bern, Freiburgstrasse 4, Bern CH-3010 (Switzerland); Vock, Peter, E-mail: peter.vock@insel.ch [Department of Diagnostic, Interventional and Pediatric Radiology, University Hospital Bern, Freiburgstrasse 4, Bern CH-3010 (Switzerland); Ruder, Thomas D., E-mail: thomas.ruder@irm.unibe.ch [Institute of Forensic Medicine, University of Bern, Freiburgstrasse 4, Bern CH-3010 (Switzerland)

    2011-08-15

    Objective: To assess the sensitivity and image quality of chest radiography (CXR) with or without dual-energy subtracted (ES) bone images in the detection of rib fractures. Materials and methods: In this retrospective study, 39 patients with 204 rib fractures and 24 subjects with no fractures were examined with a single exposure dual-energy subtraction digital radiography system. Three blinded readers first evaluated the non-subtracted posteroanterior and lateral chest radiographs alone, and 3 months later they evaluated the non-subtracted images together with the subtracted posteroanterior bone images. The locations of rib fractures were registered with confidence levels on a 3-grade scale. Image quality was rated on a 5-point scale. Marks by readers were compared with fracture localizations in CT as a standard of reference. Results: The sensivity for fracture detection using both methods was very similar (34.3% with standard CXR and 33.5% with ES-CXR, p = 0.92). At the patient level, both sensitivity (71.8%) and specificity (92.9%) with or without ES were identical. Diagnostic confidence was not significantly different (2.61 with CXR and 2.75 with ES-CXR, p = 0.063). Image quality with ES was rated higher than that on standard CXR (4.08 vs. 3.74, p < 0.001). Conclusions: Despite a better image quality, adding ES bone images to standard radiographs of the chest does not provide better sensitivity or improved diagnostic confidence in the detection of rib fractures.

  14. Confirmation of T1-Bright Vein of Galen Aneurysm Spontaneous Thrombosis by Subtraction Magnetic Resonance Venography: A Case Report

    Energy Technology Data Exchange (ETDEWEB)

    Irfan, M.; Lohman, B.; McKinney, A.M. (Dept. of Radiology/Neuroradiology, Univ. of Minnesota, Minneapolis, Minnesota (United States))

    2009-08-15

    Spontaneous thrombosis of a vein of Galen aneurysmal malformation (VOGM) is rare. We describe a 2-month-old patient with a patent VOGM and hydrocephalus, also confirmed patent at 6 months, but with subsequent lack of filling on pre-embolization catheter digital subtraction angiography (DSA) at 9 months' age. Due to the presence of T1- and T2-bright signal, noncontrast T1-weighted images (T1WI), T2-weighted images (T2WI), two-dimensional (2D) time-of-flight (TOF) magnetic resonance venography (MRV), and postcontrast T1WI were ambiguous for patency. However, subtracting the pre- from the postcontrast MRV images confirmed closure compared to subtracted images at 6 months' age. The factors contributing to thrombosis were likely a combination of a disproportionately small straight sinus, ventriculostomy, and contrast medium from DSA.

  15. Evaluation of the linear measurements by conventional radiographs and indirect digital images in the endodontic treatment Avaliação de medidas lineares por meio de radiografia convencional e digitalizada no tratamento endodôntico

    Directory of Open Access Journals (Sweden)

    Nicole Kawauchi

    2004-12-01

    Full Text Available INTRODUCTION: A successful endodontic therapy depends on the linear measurements obtained by means of radiographs taken during odontometry and also on the application of the established working length up to the final obturation. OBJECTIVE: The aim of this study was to compare the precision of the linear measurement obtained by means of conventional radiographs and indirect digital images evaluated by the Digora 1.5 software during the different stages of endodontic treatment, as well as to evaluate the tools available on this software. METHODS: A total of 160 radiographs of single-rooted teeth were obtained from files, which were analysed and divided in 4 groups comprising odontometry, cone fit, condensation and the final obturation. Analyses of the conventional radiographs and digitized images were performed by five previuosly calibrated examiners. RESULTS: A high level of inter and intra-examiner agreement was observed through application of the Kendall coefficient and the correlation index, respectively. In relation to the results of linear measurement, the two-way variance analyses and the Tukey test revealed that, concerning the method, a statistically significant decrease was observed on the measurement obtained through the digital method when compared to the conventional radiograph (pA radiologia digital tem sido amplamente difundida na odontologia, especialmente na endodontia. O sucesso do tratamento endodôntico depende das medidas lineares obtidas a partir de radiografias tomadas durante a odontometria, e do seguimento do comprimento de trabalho determinado até a obturação final. Este trabalho objetivou comparar a precisão das medidas lineares obtidas em radiografias convencionais com as imagens digitais indiretas avaliadas pelo programa Digora 1.5, durante as diferentes fases do tratamento endodôntico, bem como avaliar as ferramentas disponíveis neste programa. Foram analisadas 160 radiografias de dentes unirradiculares, dos

  16. Visualization of mocrocalcifications on mammographies obtained by digital fullfield mammography in comparison to conventional film-screen mammography; Visualisierung von Mikrokalzifikationen in digitaler Vollfeldmammographie im Vergleich zu konventioeller Film-Folien-Mammographie

    Energy Technology Data Exchange (ETDEWEB)

    Diekmann, S.; Heyden, H. von; Diekmann, F. [Humboldt-Universitaet, Berlin (Germany). Universitaetsklinikum Charite, Inst. fuer Radiologie; Bick, U. [Chicago Univ., IL (United States). Dept. of Radiology

    2003-06-01

    Purpose: To evaluate the visualization of microcalcifications on mammographies obtained by full-field digital mammography (FFDM) in comparison to conventional film-screen mammography (FSM). Material and Methods: Forty-seven digital and film-screen mammographies depicting histologically proven lesions (27 benign, 20 malignant) were assessed by 4 readers. The images obtained with the different systems were comparable in terms of positioning. Maximum time interval between film-screen mammography and digital mammography was three months. Using a questionnaire, the readers evaluated the number of microcalcifications and their subjective conspicuity for FFDM (Senographe 2000D, GE Medical Systems, Milwaukee, USA) and FSM. A 7-point scale based on the BIRADS classification was used to characterize the calcifications by means of ROC analysis. Results: No statistically significant differences were seen between the two types of mammography among the readers in assessing the number of microcalcifications. The subjective conspicuity of microcalcifications was found to be significantly better for digital mammographies. The diagnosis assigned by the readers did not show significant differences between the two systems. Conclusion: Although the subjective conspicuity of microcalcifications was found to be significantly better on digital mammography compared to film-screen mammography, there was no significant advantage of digital mammography resulting from the higher contrast resolution nor a disadvantage in terms of characterization of microcalcifications resulting from the lower spacial resolution. The advantages of digital mammography (e.g. CAD-systems, archiving, dose reduction) can be used without a loss of diagnostic quality. (orig.) [German] Zielsetzung: Mit der vorliegenden Studie soll die Erkennbarkeit von Mikroverkalkungen in der digitalen Vollfeldmammographie im Vergleich zur konventionellen Film-Folien-Mammographie evaluiert werden. Darueber hinaus soll die klinische

  17. Parallel decompositions of Mueller matrices and polarimetric subtraction

    Directory of Open Access Journals (Sweden)

    Gil J.J.

    2010-06-01

    Full Text Available From a general formulation of the physically realizable parallel decompositions of the Mueller matrix M of a given depolarizing system, a procedure for determining the set of pure Mueller matrices susceptible to be subtracted from M is presented. This procedure provides a way to check if a given pure Mueller matrix N can be subtracted from M or not. If this check is positive, the value of the relative cross section of the subtracted component is also determined.

  18. Parallel decompositions of Mueller matrices and polarimetric subtraction

    OpenAIRE

    Gil J.J.

    2010-01-01

    From a general formulation of the physically realizable parallel decompositions of the Mueller matrix M of a given depolarizing system, a procedure for determining the set of pure Mueller matrices susceptible to be subtracted from M is presented. This procedure provides a way to check if a given pure Mueller matrix N can be subtracted from M or not. If this check is positive, the value of the relative cross section of the subtracted component is also determined.

  19. 数字化导管加工与常规导管加工对比浅析%Analysis on Comparison of Digital Tube Manufacturing With Conventional Tube Manufacturing

    Institute of Scientific and Technical Information of China (English)

    王玲; 付冬雪

    2012-01-01

    By comparison and analysis of the digital tube manufacturing and conventional tube manufacturing in terms of coordination approaches, technological process and inspection methods and so on, a conclusion that the digital tube manufacturing may shorten the manufacturing cycle time and reduce the production cost is drawn, which can adapt to demands for rapid development and modification of the aircraft so as to form the core competence on the tube manufacturing for the modem aircraft.%通过数字化导管加工与常规导管加工在协调方法、工艺过程、检测方法等方面对比分析,得出数字化导管制造可以缩短制造周期、降低生产成本的结论,能够适应现代飞机快速研制及改型需求,形成现代飞机导管制造核心竞争力.

  20. Digital Full-Scope Simulation of a Conventional Nuclear Power Plant Control Room, Phase 2: Installation of a Reconfigurable Simulator to Support Nuclear Plant Sustainability

    Energy Technology Data Exchange (ETDEWEB)

    Ronald L. Boring; Vivek Agarwal; Kirk Fitzgerald; Jacques Hugo; Bruce Hallbert

    2013-03-01

    The U.S. Department of Energy’s Light Water Reactor Sustainability program has developed a control room simulator in support of control room modernization at nuclear power plants in the U.S. This report highlights the recent completion of this reconfigurable, full-scale, full-scope control room simulator buildout at the Idaho National Laboratory. The simulator is fully reconfigurable, meaning it supports multiple plant models developed by different simulator vendors. The simulator is full-scale, using glasstop virtual panels to display the analog control boards found at current plants. The present installation features 15 glasstop panels, uniquely achieving a complete control room representation. The simulator is also full-scope, meaning it uses the same plant models used for training simulators at actual plants. Unlike in the plant training simulators, the deployment on glasstop panels allows a high degree of customization of the panels, allowing the simulator to be used for research on the design of new digital control systems for control room modernization. This report includes separate sections discussing the glasstop panels, their layout to mimic control rooms at actual plants, technical details on creating a multi-plant and multi-vendor reconfigurable simulator, and current efforts to support control room modernization at U.S. utilities. The glasstop simulator provides an ideal testbed for prototyping and validating new control room concepts. Equally importantly, it is helping create a standardized and vetted human factors engineering process that can be used across the nuclear industry to ensure control room upgrades maintain and even improve current reliability and safety.

  1. Experiment on digital CDS with 33-M pixel 120-fps super hi-vision image sensor

    Science.gov (United States)

    Yonai, J.; Yasue, T.; Kitamura, K.; Hayashida, T.; Watabe, T.; Shimamoto, H.; Kawahito, S.

    2014-03-01

    We have developed a CMOS image sensor with 33 million pixels and 120 frames per second (fps) for Super Hi-Vision (SHV:8K version of UHDTV). There is a way to reduce the fixed pattern noise (FPN) caused in CMOS image sensors by using digital correlated double sampling (digital CDS), but digital CDS methods need high-speed analog-to-digital conversion and are not applicable to conventional UHDTV image sensors due to their speed limit. Our image sensor, on the other hand, has a very fast analog-to-digital converter (ADC) using "two-stage cyclic ADC" architecture that is capable of being driven at 120-fps, which is double the normal frame rate for TV. In this experiment, we performed experimental digital CDS using the high-frame rate UHDTV image sensor. By reading the same row twice at 120-fps and subtracting dark pixel signals from accumulated pixel signals, we obtained a 60-fps equivalent video signal with digital noise reduction. The results showed that the VFPN was effectively reduced from 24.25 e-rms to 0.43 e-rms.

  2. Analysis of Hysterosalpingography in 1369 Infertility Patients with Water Soluble Contrast Medium under Digital Subtraction Angiography%1369例不孕患者水溶性造影剂DSA下动态子宫输卵管造影分析

    Institute of Scientific and Technical Information of China (English)

    田芳玲; 陈硕飞; 王海峰; 曲尔青; 郭晓丽; 田锦林

    2014-01-01

    目的:探讨原发性不孕(PI)与继发性不孕(SI)患者子宫输卵管造影(HSG)的特点及导致输卵管不通畅的危险因素。方法回顾性分析1369例不孕患者的水溶性造影剂DSA下HSG造影资料,根据不孕的原因为PI及SI两组,对两组一般情况及造影结果进行比较;再以双侧输卵管通畅与否为因变量,以年龄、生育史、是否有宫外孕史、盆腔手术史、输卵管结核病史、流产史、原发或继发性不孕、合并其它疾病与否、子宫形态异常与否为自变量,进行多因素二分类logistic回归分析,探讨输卵管不通畅的危险因素。结果 PI组年龄比SI组小[(27.27±3.82)岁vs(29.97±4.80)岁],双侧输卵管通畅率较SI组高(45.50%vs 34.74%),两组比较有统计学差异(P<0.05);Logistic回归分析显示年龄、宫外孕史、流产史及子宫形态异常是输卵不通畅的危险因素(OR值=0.903、0.198、1.542、0.120;95%的可信区间:0.903~0.958、0.120~0.352、1.002~2.375、0.036~0.399)。结论 PI和SI在年龄及输卵管通畅率方面存在差异,大龄、宫外孕史、流产史及子宫形态异常是输卵不通畅的危险因素。%Objective To analysis the hysterosalpingography(HSG) features of primary infertile(PI) and secondary infertile(SI) patients and related risk factors of Fallopian tubal blockage and incomplete patency. Methods Digital subtraction angiography(DSA) imaging data of HSG with water soluble contrast medium in 1369 infertile patients were retrospectively analyzed. Patients were divided into two groups according to etiopathogenisis of infertility, including PI group and SI group. The general states and appearance of HSG were compared between the two groups. And then, with bilateral tubal patency or not as a dependent, and with age,childbearing history or not, ectopic pregnancy(EP) history or not, pelvic surgery history or not, tubal tuberculosis history or not

  3. Analysis of the anatomical relationship between the uterine artery and the bony landmarks in cesarean scar pregnancy by CT angiography and digital subtraction angiography%剖宫产瘢痕妊娠子宫动脉开口位置与骨性标志关系的 CT 血管成像与DSA 研究

    Institute of Scientific and Technical Information of China (English)

    熊浪; 王进华; 孙进; 邓美香; 郑伟增; 肖新兰

    2015-01-01

    目的:利用 CTA 与 DSA 技术,采用骶髂垂直分段定位法探讨剖宫产术后子宫瘢痕妊娠(CSP)患者子宫动脉开口位置与骨性解剖标志的关系。方法回顾性分析2013年10月—2014年6月浙江大学医学院附属妇产科医院收治的91例 CSP 患者的临床资料和 CTA、DSA 影像学资料。患者年龄23~44岁,平均(32.7±4.2)岁。在骶髂关节骶骨面中,以骶骨的最高点(如左侧 A 点)与髂骨左右两侧的最低点(a、b)为骨盆骨性解剖标志。采用骶髂垂直分段定位法连接 a、b 两点做一水平线 ab,从 A 点向 ab 水平线做一垂线,交点为 D 点,B、C 等分 AD,将骶髂垂直等分为 AB、BC、CD 和 D点远端4段,在患者 CTA 与 DSA 图片上,观察统计患者双侧子宫动脉开口位置在各段的分布情况。结果91例182支子宫动脉中,3支子宫动脉已结扎,CTA 与 DSA 均未见其显示;179支子宫动脉显影,子宫动脉开口位置左侧低于右侧,左侧在 AB、BC、CD 及 D 点远端的比例为0%(0)、3.3%(3/90)、70.0%(63/90)及26.7%(24/90),右侧的比例为0%(0)、11.2%(10/89)、85.4%(76/89)及3.4%(3/89),左右两侧均以 CD 段所占比例最多,两侧在各段分布构成情况差异有统计学意义(χ2=22.618,P <0.01)。结论 CSP 患者子宫动脉开口位置在骶髂各段中分布具有一定的特征,当 CSP患者子宫动脉栓塞治疗无法准确判断子宫动脉开口位置时,利用骶髂垂直分段定位法可为介入治疗提供新的影像学指导和参考。%Objective To investigate the anatomical relationship between the uterine artery and the adjacent bony landmarks in cesarean scar pregnancy ( CSP ) with the method of sacroiliac vertical segmentation localization using CT angiography ( CTA ) and digital subtraction angiography ( DSA ). Methods From October 2013 to June 2014, 91 patients of CSP were examined by CTA and DSA in Department of Radiology of the Women′s Hospital of Medicine Zhejiang University. The

  4. 多层螺旋CT与数字减影血管造影诊断下消化道出血的比较%Comparison Between Multislice Spiral CT and Digital Subtraction Angiography in the Diagnosis of Lower Digestive Tract Hemorrhage

    Institute of Scientific and Technical Information of China (English)

    石磊; 邹文远; 陈光斌; 胡久民

    2012-01-01

    目的:通过与数字减影血管造影(DSA)的对照分析,评价多层螺旋CT(MSCT)对下消化道出血的诊断价值.方法:临床怀疑下消化道出血的29例患者进行MSCT增强扫描,并结合MSCT多平面重组(MPR)、最大密度投影(MIP)等后处理模式对图像进行分析判断,找出出血部位及供血动脉,与DSA对照来评估MSCT血管成像技术对于显示下消化道出血的敏感性、准确率.结果:①MSCT显示出血部位25例,出血显示率86.2%(25/29).DSA检查发现出血灶22例,出血显示率75.9% (22/29).MSCT对于发现出血部位的敏感性和DSA无显著差异(P>0.05).②MSCT显示以下出血部位:空回肠出血9例,结肠出血16例,诊断肿瘤15例,炎症4例,憩室2例,溃疡2例,血管畸形1例,未明确病因1例.MSCT未见异常的4例DSA均表现阴性.DSA显示的出血部位:小肠8例,结肠14例,术中诊断肿瘤10例,血管畸形1例,其余11例未明确病因.统计结果表明:MSCT对于下消化道出血的病因诊断准确率明显高于DSA(P<0.05).结论:MSCT对于判断下消化道出血部位的敏感性可与DSA相媲美,并且能较准确地进行病因诊断,具有较高的临床应用价值,可作为下消化道出血性疾病的常规首选检查方法.%Objective: To evaluate multislice spiral CT (MSCT) in the diagnosis of lower digestive tract hemorrhage as compared with digital subtraction angiography (DSA). Methods: Twenty-nine cases of suspected lower digestive tract bleeding received MSCT enhanced scan, combined with multiplanar reformation (MPR) , maximum intensity projection (MIP) image analysis, to identify the bleeding site and the supplying artery. The results were compared with those of DSA to evaluate the sensitivity and accuracy of MSCT. Results: MSCT showed the bleeding sites of the 25 cases (86.2%) while DSA found 22 sites of bleeding (75. 9%). MSCT showed 9 cases of jejunum and ileum bleeding, 16 cases of colonic bleeding, 15 cases of tumor, 4 cases of

  5. Astronomical Image Subtraction by Cross-Convolution

    Science.gov (United States)

    Yuan, Fang; Akerlof, Carl W.

    2008-04-01

    In recent years, there has been a proliferation of wide-field sky surveys to search for a variety of transient objects. Using relatively short focal lengths, the optics of these systems produce undersampled stellar images often marred by a variety of aberrations. As participants in such activities, we have developed a new algorithm for image subtraction that no longer requires high-quality reference images for comparison. The computational efficiency is comparable with similar procedures currently in use. The general technique is cross-convolution: two convolution kernels are generated to make a test image and a reference image separately transform to match as closely as possible. In analogy to the optimization technique for generating smoothing splines, the inclusion of an rms width penalty term constrains the diffusion of stellar images. In addition, by evaluating the convolution kernels on uniformly spaced subimages across the total area, these routines can accommodate point-spread functions that vary considerably across the focal plane.

  6. Reduction of radiation dose by using digital luminescence radiography compared to conventional screen film system with grid cassette; Reduktion der Strahlendosis mittels Speicherfolienradiographie im Vergleich zum konventionellen Film-Folien-System mit Rasterkassette am Schaedelphantom

    Energy Technology Data Exchange (ETDEWEB)

    Heyne, J.P.; Merbold, H.; Neumann, R.; Freesmeyer, M.; Jonetz-Mentzel, L.; Kaiser, W.A. [Friedrich-Schiller-Univ. Jena, Inst. fuer Diagnostische und Interventionelle Radiologie (Germany); Sehner, J. [AGFA-Deutschland, Vertriebsgesellschaft (Germany)

    1999-07-01

    Purpose: How much can the radiation dose be reduced for skull radiography by using digital luminescence radiography (DLR) compared to a conventional screen film system with a grid cassette? Methods and Materials: A skull phantom (3M) was X-rayed in anterior-posterior orientation using both a conventional screen film system with grid cassette and DLR (ADC-70, Agfa). The tube current time product (mAs) was diminished gradually while keeping the voltage constant. The surface entrance dose was measured by a sensor of Dosimax (Wellhoefer). Five investigators evaluated the images by characteristic and critical features, spatial resolution and contrast. Results: The surface entrance dose at 73 kV/22 mAs was 0,432 mGy in conventional screen film system and 0,435 mGy in DLR. The images could be evaluated very well down to an average dose of 71% (0,308 mGy; SD 0,050); sufficient images were obtained down to an average dose of 31% (0,136 mGy; SD 0,065). The resolution of the line pairs were reduced down to a 2 levels depending on the investigator. Contrast was assessed as being very good to sufficient. The acceptance of the postprocessed images (MUSICA-software) was individually different and resultde in an improvement of the assessment of bone structures an contrast in higher dose ranges only. Conclusion: For the sufficient assessment of a possible fracture/of paranasal sinuses/of measurement the skull the dose can be reduced to at least 56% (31%; SD 14,9%)/40% (27%; SD 9,3%)/18% (14%; SD 4,4%). Digital radiography allows question-referred exposure parameters with clearly reduced dose, so e.g. for fracture exclusion 73 kV/12,5 mAs and to skull measurement 73 kV/4 mAs. (orig.) [Deutsch] Ziel: Wie weit kann unter Einsatz der rasterlosen Speicherfolienradiographie bei einer Schaedelaufnahme die Strahlendosis im Vergleich zum Film-Folien-System (FFS) mit Rasterkassette (RK) fragestellungsbezogen gesenkt werden? Material und Methode: Ein Schaedelphantom (3M) wurde konventionell

  7. Digital imaging primer

    CERN Document Server

    Parkin, Alan

    2016-01-01

    Digital Imaging targets everyyone with an interest in digital imaging, be they professional or private, who uses even quite modest equipment such as a PC, digital camera and scanner, a graphics editor such as Paint, and an inkjet printer. Uniquely, it is intended to fill the gap between highly technical texts for academics (with access to expensive equipment) and superficial introductions for amateurs. The four-part treatment spans theory, technology, programs and practice. Theory covers integer arithmetic, additive and subtractive color, greyscales, computational geometry, and a new presentation of discrete Fourier analysis; Technology considers bitmap file structures, scanners, digital cameras, graphic editors, and inkjet printers; Programs develops several processing tools for use in conjunction with a standard Paint graphics editor and supplementary processing tools; Practice discusses 1-bit, greyscale, 4-bit, 8-bit, and 24-bit images for the practice section. Relevant QBASIC code is supplied an accompa...

  8. Tomography of photon-added and photon-subtracted states

    NARCIS (Netherlands)

    Bazrafkan, MR; Man'ko, [No Value

    2003-01-01

    The purpose of this paper is to introduce symplectic and optical tomograms of photon-added and photon-subtracted quantum states. Explicit relations for the tomograms of photon-added and photon-subtracted squeezed coherent states and squeezed number states are obtained. Generating functions for the m

  9. Developing a Model to Support Students in Solving Subtraction

    NARCIS (Netherlands)

    Murdiyani, N.M.; Zulkardi, Z.; Putri, R.I.; van Eerde, H.A.A.; van Galen, F.H.J.

    2013-01-01

    Subtraction has two meanings and each meaning leads to the different strategies. The meaning of “taking away something” suggests a direct subtraction, while the meaning of “determining the difference between two numbers” is more likely to be modeled as indirect addition. Many prior researches found

  10. Developing a Model to Support Students in Solving Subtraction

    NARCIS (Netherlands)

    Murdiyani, N.M.; Zulkardi, Z.; Putri, R.I.; van Eerde, H.A.A.|info:eu-repo/dai/nl/071855343; van Galen, F.H.J.|info:eu-repo/dai/nl/069437025

    2013-01-01

    Subtraction has two meanings and each meaning leads to the different strategies. The meaning of “taking away something” suggests a direct subtraction, while the meaning of “determining the difference between two numbers” is more likely to be modeled as indirect addition. Many prior researches found

  11. Developing a Model to Support Students in Solving Subtraction

    Science.gov (United States)

    Murdiyani, Nila Mareta; Zulkardi; Putri, Ratu Ilma Indra; van Eerde, Dolly; van Galen, Frans

    2013-01-01

    Subtraction has two meanings and each meaning leads to the different strategies. The meaning of "taking away something" suggests a direct subtraction, while the meaning of "determining the difference between two numbers" is more likely to be modeled as indirect addition. Many prior researches found that the second meaning and…

  12. Tomography of photon-added and photon-subtracted states

    NARCIS (Netherlands)

    Bazrafkan, MR; Man'ko, [No Value

    The purpose of this paper is to introduce symplectic and optical tomograms of photon-added and photon-subtracted quantum states. Explicit relations for the tomograms of photon-added and photon-subtracted squeezed coherent states and squeezed number states are obtained. Generating functions for the

  13. NULL Convention Floating Point Multiplier

    OpenAIRE

    Anitha Juliette Albert; Seshasayanan Ramachandran

    2015-01-01

    Floating point multiplication is a critical part in high dynamic range and computational intensive digital signal processing applications which require high precision and low power. This paper presents the design of an IEEE 754 single precision floating point multiplier using asynchronous NULL convention logic paradigm. Rounding has not been implemented to suit high precision applications. The novelty of the research is that it is the first ever NULL convention logic multiplier, designed to p...

  14. Efficacy of conventional and digital radiographic imaging methods for diagnosis of simulated external root resorption Eficácia dos métodos radiográficos convencional e digital no diagnóstico de reabsorções radiculares simuladas

    Directory of Open Access Journals (Sweden)

    Vânia Portela Ditzel Westphalen

    2004-06-01

    Full Text Available This in vitro study evaluated and compared the efficacy of conventional (Kodak F-speed (Insight, Kodak and a digital (DRS Gnatus System, Gnatus radiographic imaging for diagnosis of simulated external root resorption cavities. Human mandibles containing teeth were covered with bovine muscle slices in order to simulate the soft tissues. Nine teeth out of each group of teeth were investigated. Initially, three periapical radiographs of each tooth were taken using a tube shift technique with mesial and distal angulations in both methods. All teeth were subsequently extracted and had 0.7 and 1.0-mm deep cavities prepared on their buccal, mesial and distal surfaces at the cervical, middle and apical thirds. Steel cylinder burs (DORMER® - HSS with 0.7 and 1.0-mm diameter were used. Each tooth was replaced on its socket and new radiographs were taken. Three examiners, an endodontist (1, a radiologist (2 and a general dentist (3, evaluated the images. Results were compared by z-test and showed a higher number of cavities detected by the digital method compared to the conventional, regardless of the deepness of the cavity. In decreasing order, examiners 2, 3 and 1 exhibited different potentials of detection of cavities with the conventional method. Examiners 1 and 3 exhibited superior potential than examiner 2 for detection of cavities of different sizes with the digital method.O presente estudo visou avaliar e comparar, in vitro, a eficácia dos métodos radiográficos convencional (filmes de grupos de sensibilidade E/F Kodak Insight e digital (Sistema Gnatus DRS, no diagnóstico de cavidades simulando reabsorções radiculares externas, em dentes contidos em mandíbulas humanas secas com músculo bovino simulando o tecido mole. As variáveis consideradas foram: tamanhos das cavidades e examinadores envolvidos. Foram utilizadas nove unidades de cada grupo dentário, incisivos (central e lateral, caninos, pré-molares e molares, sem lesões periapicais

  15. [Construction of subtractive cDNA libraries of the sporogony stage of Eimeria tenella by suppression subtractive hybridization].

    Science.gov (United States)

    Han, Hong-Yu; Lin, Jiao-Jiao; Zhao, Qi-Ping; Dong, Hui; Jiang, Lian-Lian; Wang, Xin; Han, Jing-Fang; Huang, Bing

    2007-11-01

    In order to clone and identify differentially expressed genes in the sporogony stage of Eimeria tenella, the cDNAs from unsporulated oocysts and sporulated oocysts of E. tenella were used as driver, respectively, the cDNAs from sporozoites of E. tenella was used tester, Two subtractive cDNA libraries of sporozoites were constructed by using the technique of suppression subtractive hybridization (SSH). the cDNAs from unsporulated oocysts was used driver, the cDNAs from sporulated ooceysts was used tester, one subtractive cDNA library of sporulated oocysts was constructed. PCR amplification revealed that the two subtractive cDNA libraries of sporozoites and one subtractive cDNA library of sporulated oocysts contained approximated 96%, 96% and 98% recombinant clones, respectively. Fifty positive clones were sequenced and analyzed in GenBank with Blast search from three subtractive cDNA libraries, respectively, thirteen unique sequences were found from the subtractive cDNA library of sporulated oocysts, eight ESTs shared significant identity with previously described. A total of forty unique sequences were obtained from the two subtractive cDNA libraries, nine ESTs shared significant identity with previously described, the other sequences represent novel genes of E. tenella with no significant homology to the proteins in Genbank. These results have provided the foundation for cloning new genes of E. tenella and further studying new approaches to control coccidiosis.

  16. Accessing the diffracted wavefield by coherent subtraction

    Science.gov (United States)

    Schwarz, Benjamin; Gajewski, Dirk

    2017-10-01

    Diffractions have unique properties which are still rarely exploited in common practice. Aside from containing subwavelength information on the scattering geometry or indicating small-scale structural complexity, they provide superior illumination compared to reflections. While diffraction occurs arguably on all scales and in most realistic media, the respective signatures typically have low amplitudes and are likely to be masked by more prominent wavefield components. It has been widely observed that automated stacking acts as a directional filter favouring the most coherent arrivals. In contrast to other works, which commonly aim at steering the summation operator towards fainter contributions, we utilize this directional selection to coherently approximate the most dominant arrivals and subtract them from the data. Supported by additional filter functions which can be derived from wave front attributes gained during the stacking procedure, this strategy allows for a fully data-driven recovery of faint diffractions and makes them accessible for further processing. A complex single-channel field data example recorded in the Aegean sea near Santorini illustrates that the diffracted background wavefield is surprisingly rich and despite the absence of a high channel count can still be detected and characterized, suggesting a variety of applications in industry and academia.

  17. Evaluating Digital Strategies for Storing and Retrieving Scholarly Information.

    Science.gov (United States)

    Getz, Malcolm

    1997-01-01

    Outlines the advantages of digital documents for scholars and offers considerations for designing systems for storing and retrieving digital information products. Discusses conventional and electronic storage and retrieval; network costs; digital storage; search strategies; acquisition prices; and digital initiatives. (AEF)

  18. Manifestations of hepatic cavernous hemangioma in carbon dioxidedigital subtraction angiography

    Institute of Scientific and Technical Information of China (English)

    LU Wei; LI Yan-ha0; HE Xiao-feng; CHEN Yong; ZENG Qing-le

    2002-01-01

    Objective: To describe the characteristic appearance of cavernous hemangioma of the liver (CHL)presented in carbon dioxide digital subtraction angiography (CO2-DSA) and to evaluate the significance of CO2-DSA in the diagnosis of CHL. Methods: Both CO2-DSA and iodinated contrast DSA (IC-DSA) were performed in all 16 patients with CHL, and the angiographic manifestations in the same patients were compared. The image quality was rated by three experienced angiographers, and the complications were also assessed. Results; There was good correlation between angiographers on image quality (R=0. 73). Diagnostic images were obtained with both CO2-DSA and IC-DSA in all CHL patients. No difference was noted between IC-DSA and CO2-DSA in visualizing the proper hepatic arteries and its branches (P>0. 05). CO2-DSA produced better images that clearly described the tumor size, shape and margination than those by IC-DSA (P<0. 05), but both demonstrated characteristic appearances of early opacification and persistent contrast enhancement of the tumors. The portal vein branches near the tumors were constantly demonstrated by CO2-DSA in 15 cases (15/16) but only in 2 cases (2/16) by IC-DSA. Conclusion: CO2-DSA is sensitive in CHL diagnosis, and in patients with contraindications to IC or with unsatisfactory imaging results by IC-DSA,CO2-DSA is a good alternative. As show in most cases by CO2-DSA, the portal veins might act as the main drainage vein of CHLs.

  19. Bi-Event Subtraction Technique at Hadron Colliders

    CERN Document Server

    Dutta, Bhaskar; Kolev, Nikolay; Krislock, Abram

    2011-01-01

    We propose the Bi-Event Subtraction Technique (BEST) as a method of modeling and subtracting large portions of the combinatoric background which arises during reconstruction of particle decay chains at particle colliders. The combinatoric background arises because it is impossible to know experimentally which observed particles come from the decay chain of interest. BEST models this combinatoric background by combining observable particles from different collision events. The combinatoric background modeled by BEST can then be subtracted away, greatly reducing the overall background. This technique can be applied towards two goals of hadron colliders: To improve our understanding of the Standard Model and to search for new physics beyond the Standard Model.

  20. Analysis of enlarged images using time-of-flight magnetic resonance angiography, computed tomography, and conventional angiography.

    Science.gov (United States)

    Heo, Yeong-Cheol; Lee, Hae-Kag; Yang, Han-Jun; Cho, Jae-Hwan

    2014-12-01

    This study aimed to assess the accuracy of time-of-flight magnetic resonance angiography, computed tomography, and conventional angiography in depicting the actual length of the blood vessels. Three-dimensional time-of-flight magnetic resonance angiography and computed tomography angiography were performed using a flow phantom model that was 2.11 mm in diameter and had a total area of 0.26 cm(2). After this, volume rendering technique and the maximum intensity projection method as well as two-dimensional digital subtraction angiography and three-dimensional rotational angiography based on conventional angiography were conducted. For three-dimensional time-of-flight magnetic resonance angiography, 8 channel sensitivity encoding (SENSE) head coil for the 3.0 Tesla equipment was used. Fluid was added to the normal saline solution at various rates, such as 11.4, 20.0, 31.4, 40.0, 51.5, 60.0, 71.5, 80.1, 91.5, and 100.1 cm/s using an automatic contrast media injector. Each image was thoroughly examined. After reconstructing the image using the maximum intensity projection method, the length of the conduit in the center of the coronal plane was measured 30 times. After performing computed tomography angiography with the 64-channel CT scanner and 16-channel CT scanner, the images were sent to TeraRecon. Then, the length of the conduit in the center of the coronal plane of each image was measured 30 times after reconstructing the images using volume rendering and maximum intensity projection techniques. For conventional angiography, three-dimensional rotational angiography and two-dimensional digital subtraction angiography were used. Images obtained by three-dimensional rotational angiography were reconstructed and enhanced by 33, 50, and 100 % in the 128 Matrix and the 256 Matrix, respectively on the Xtra Vision workstation. The maximum intensity projection was used for the reconstruction, and the length of the conduit was measured 30 times in the center of the coronal

  1. Comparison between a digital scanning system and a conventional screen film system in the full spine radiological procedure in pediatrics; Valoracion de un sistema de Scan digital frente a un sistema convencional cartulina pelicula en exploraciones de columna total en pediatria

    Energy Technology Data Exchange (ETDEWEB)

    Espana, M. L.; Gomez, G.; Romero, A.; Minambres, A.; Albi, G.; Floriano, A.; Rodirguez, A.; Lopez Franco, P.

    2004-07-01

    To compare from both dosimetry and image quality standpoints, a digital scanning system with a conventional screen film system, in the full spine radiological procedure. The standard patient is considered to be 12 years old, and a sample of forty patients referred for full spine radiological procedure has been studied. Gonad shielding has been used in all the patients, and its efficiency has been evaluated. Dosimetric study includes Kerma-area product, and thorax and gonad entrance surface dose. Kerma area product has been measured using a transmission camera, and for entrance surface dose estimation both thermoluminescent dosemeter LiF: Mg, Cu, P and LiF: Mg, Ti have been utilized. Three radiologists have evaluated the image quality according to the degree of fulfilment of the image quality criteria. (Author) 22 refs.

  2. Análise de Custo-efetividade do rastreamento do câncer de mama com mamografia convencional, digital e ressonância Analysis of Cost-effectiveness of screening for breast cancer with conventional mammography, digital and magnetic resonance imaging

    Directory of Open Access Journals (Sweden)

    Antonio Augusto de Freitas Peregrino

    2012-01-01

    Full Text Available O objetivo deste trabalho foi realizar análise de custo efetividade da intervenção das mamografias convencional e digital e da ressonância magnética no rastreamento de câncer de mama, comparando com o não rastreamento. Foi construído um modelo markoviano, numa uma coorte hipotética de 100 mil mulheres com rastreamento bianual, cuja linha de base é a história natural da doença. Modelaram-se quatro cenários distintos: (1 a história natural do câncer de mama como linha de base; (2 mamografia com filme convencional; (3 mamografia digital e (4 e ressonância magnética. Os custos dos cenários modelados variaram desde R$ 194.216,68 para a história natural, até R$ 48.614.338,31 para o rastreamento com ressonância magnética. As diferenças de efetividade entre as intervenções variaram de 300 até 78.000 anos de vida ganhos, na coorte de 100 mil mulheres. Em relação à Razão de Custo-Efetividade Incremental, em termos de custo por ano de vida ganhos, a estratégia do rastreamento mamográfico convencional produziu um ano extra por R$ 13.573,07. A Razão de Custo Efetividade Incremental (ICER da ressonância magnética foi de R$ 2.904.328,88 em relação ao não rastreamento. O estudo mostrou que é mais custo-efetivo realizar o rastreamento com a mamografia convencional do que as outras tecnologias de intervenção.A cost-effectiveness analysis was conducted in screening for breast cancer. The use of conventional mammography, digital and magnetic resonance imaging were compared with natural disease history as a baseline. A Markov model projected breast cancer in a group of 100,000 women for a 30 year period, with screening every two years. Four distinct scenarios were modeled: (1 the natural history of breast cancer, as a baseline, (2 conventional film mammography, (3 digital mammography and (4 magnetic resonance imaging. The costs of the scenarios modeled ranged from R$ 194.216,68 for natural history, to R$ 48.614.338,31, for

  3. Improvements in floating point addition/subtraction operations

    Energy Technology Data Exchange (ETDEWEB)

    Farmwald, P.M.

    1984-02-24

    Apparatus is described for decreasing the latency time associated with floating point addition and subtraction in a computer, using a novel bifurcated, pre-normalization/post-normalization approach that distinguishes between differences of floating point exponents.

  4. An auto-adaptive background subtraction method for Raman spectra

    Science.gov (United States)

    Xie, Yi; Yang, Lidong; Sun, Xilong; Wu, Dewen; Chen, Qizhen; Zeng, Yongming; Liu, Guokun

    2016-05-01

    Background subtraction is a crucial step in the preprocessing of Raman spectrum. Usually, parameter manipulating of the background subtraction method is necessary for the efficient removal of the background, which makes the quality of the spectrum empirically dependent. In order to avoid artificial bias, we proposed an auto-adaptive background subtraction method without parameter adjustment. The main procedure is: (1) select the local minima of spectrum while preserving major peaks, (2) apply an interpolation scheme to estimate background, (3) and design an iteration scheme to improve the adaptability of background subtraction. Both simulated data and Raman spectra have been used to evaluate the proposed method. By comparing the backgrounds obtained from three widely applied methods: the polynomial, the Baek's and the airPLS, the auto-adaptive method meets the demand of practical applications in terms of efficiency and accuracy.

  5. Increasing Entanglement between Gaussian States by Coherent Photon Subtraction

    DEFF Research Database (Denmark)

    Ourjoumtsev, Alexei; Dantan, Aurelien Romain; Tualle Brouri, Rosa

    2007-01-01

    We experimentally demonstrate that the entanglement between Gaussian entangled states can be increased by non-Gaussian operations. Coherent subtraction of single photons from Gaussian quadrature-entangled light pulses, created by a nondegenerate parametric amplifier, produces delocalized states w...

  6. Subtraction gadolinium enhanced magnetic resonance for head and neck imaging

    Energy Technology Data Exchange (ETDEWEB)

    Lloyd, G.A.S.; Barker, P.G.; Phelps, P.D. (Royal National Throat, Nose and Ear Hospital, London (United Kingdom))

    1993-01-01

    The subtraction method of Des Plantes was applied to gadolinium enhanced magnetic resonance imaging (GdMR). Using short acquisition times, T[sub 1] weighted spin echo pulse sequences are made immediately before and after intravenous administration of gadolinium DTPA. The needle is placed in the vein prior to putting the patient into the scanner and is irrigated with saline while the control series is obtained. 42 patients with naso-sinus or skull base tumours have been successfully investigated by this technique and satisfactory subtraction studies are now obtained on all patients other than the claustrophobic. Subtraction GdMR provides the best demonstration of the effects of gadolinium DTPA on the magnetic resonance signal for both normal and abnormal tissues. Tbe signal recorded on the subtraction image is dependent on tissue blood supply and provides a more accurate record of tumour extent than that shown by unsubtracted GdMR scans. (author).

  7. Background Subtraction for Automated Multisensor Surveillance: A Comprehensive Review

    Directory of Open Access Journals (Sweden)

    Cristani Marco

    2010-01-01

    Full Text Available Background subtraction is a widely used operation in the video surveillance, aimed at separating the expected scene (the background from the unexpected entities (the foreground. There are several problems related to this task, mainly due to the blurred boundaries between background and foreground definitions. Therefore, background subtraction is an open issue worth to be addressed under different points of view. In this paper, we propose a comprehensive review of the background subtraction methods, that considers also channels other than the sole visible optical one (such as the audio and the infrared channels. In addition to the definition of novel kinds of background, the perspectives that these approaches open up are very appealing: in particular, the multisensor direction seems to be well-suited to solve or simplify several hoary background subtraction problems. All the reviewed methods are organized in a novel taxonomy that encapsulates all the brand-new approaches in a seamless way.

  8. Background Subtraction for Automated Multisensor Surveillance: A Comprehensive Review

    Science.gov (United States)

    Cristani, Marco; Farenzena, Michela; Bloisi, Domenico; Murino, Vittorio

    2010-12-01

    Background subtraction is a widely used operation in the video surveillance, aimed at separating the expected scene (the background) from the unexpected entities (the foreground). There are several problems related to this task, mainly due to the blurred boundaries between background and foreground definitions. Therefore, background subtraction is an open issue worth to be addressed under different points of view. In this paper, we propose a comprehensive review of the background subtraction methods, that considers also channels other than the sole visible optical one (such as the audio and the infrared channels). In addition to the definition of novel kinds of background, the perspectives that these approaches open up are very appealing: in particular, the multisensor direction seems to be well-suited to solve or simplify several hoary background subtraction problems. All the reviewed methods are organized in a novel taxonomy that encapsulates all the brand-new approaches in a seamless way.

  9. Anatomical noise in contrast-enhanced digital mammography. Part II. Dual-energy imaging

    Energy Technology Data Exchange (ETDEWEB)

    Hill, Melissa L.; Yaffe, Martin J. [Sunnybrook Research Institute, 2075 Bayview Avenue, Toronto, Ontario M4N 3M5, Canada and Department of Medical Biophysics, University of Toronto, 2075 Bayview Avenue, Toronto, Ontario M4N 3M5 (Canada); Mainprize, James G. [Sunnybrook Research Institute, 2075 Bayview Avenue, Toronto, Ontario M4N 3M5 (Canada); Carton, Ann-Katherine; Saab-Puong, Sylvie; Iordache, Răzvan; Muller, Serge [GE Healthcare, 283 rue de la Minière, Buc 78530 (France); Jong, Roberta A. [Breast Imaging, Sunnybrook Health Sciences Centre, 2075 Bayview Avenue, Toronto, Ontario M4N 3M5 (Canada); Dromain, Clarisse [Department of Radiology, Institut Gustave Roussy, 39 rue Camille Desmoulin, Villejuif 94805 (France)

    2013-08-15

    Purpose: Dual-energy (DE) contrast-enhanced digital mammography (CEDM) uses an iodinated contrast agent in combination with digital mammography (DM) to evaluate lesions on the basis of tumor angiogenesis. In DE imaging, low-energy (LE) and high-energy (HE) images are acquired after contrast administration and their logarithms are subtracted to cancel the appearance of normal breast tissue. Often there is incomplete signal cancellation in the subtracted images, creating a background “clutter” that can impair lesion detection. This is the second component of a two-part report on anatomical noise in CEDM. In Part I the authors characterized the anatomical noise for single-energy (SE) temporal subtraction CEDM by a power law, with model parameters α and β. In this work the authors quantify the anatomical noise in DE CEDM clinical images and compare this with the noise in SE CEDM. The influence on the anatomical noise of the presence of iodine in the breast, the timing of imaging postcontrast administration, and the x-ray energy used for acquisition are each evaluated.Methods: The power law parameters, α and β, were measured from unprocessed LE and HE images and from DE subtracted images to quantify the anatomical noise. A total of 98 DE CEDM cases acquired in a previous clinical pilot study were assessed. Conventional DM images from 75 of the women were evaluated for comparison with DE CEDM. The influence of the imaging technique on anatomical noise was determined from an analysis of differences between the power law parameters as measured in DM, LE, HE, and DE subtracted images for each subject.Results: In DE CEDM, weighted image subtraction lowers β to about 1.1 from 3.2 and 3.1 in LE and HE unprocessed images, respectively. The presence of iodine has a small but significant effect in LE images, reducing β by about 0.07 compared to DM, with α unchanged. Increasing the x-ray energy, from that typical in DM to a HE beam, significantly decreases α by about 2

  10. Differential cDNA cloning by enzymatic degrading subtraction (EDS).

    OpenAIRE

    1994-01-01

    We describe a new method, called enzymatic degrading subtraction (EDS), for the construction of subtractive libraries from PCR amplified cDNA. The novel features of this method are that i) the tester DNA is blocked by thionucleotide incorporation; ii) the rate of hybridization is accelerated by phenol-emulsion reassociation; and iii) the driver cDNA and hybrid molecules are enzymatically removed by digestion with exonucleases III and VII rather than by physical partitioning. We demonstrate th...

  11. IR subtraction schemes. Integrating the counterterms at NNLO in QCD

    Energy Technology Data Exchange (ETDEWEB)

    Bolzoni, Paolo; Somogyi, Gabor

    2010-06-15

    We briefly review a subtraction scheme for computing radiative corrections to QCD jet cross sections that can be defined at any order in perturbation theory. Hereafter we discuss the computational methods used to evaluate analytically and numerically the integrated counterterms arising from such a subtraction scheme. Basically these methods the Mellin-Barnes (MB) representations technique together with the harmonic summation and the sector decomposition. (orig.)

  12. Statistically tuned Gaussian background subtraction technique for UAV videos

    Indian Academy of Sciences (India)

    R Athi Lingam; K Senthil Kumar

    2014-08-01

    Background subtraction is one of the efficient techniques to segment the targets from non-informative background of a video. The traditional background subtraction technique suits for videos with static background whereas the video obtained from unmanned aerial vehicle has dynamic background. Here, we propose an algorithm with tuning factor and Gaussian update for surveillance videos that suits effectively for aerial videos. The tuning factor is optimized by extracting the statistical features of the input frames.With the optimized tuning factor and Gaussian update an adaptive Gaussian-based background subtraction technique is proposed. The algorithm involves modelling, update and subtraction phases. This running Gaussian average based background subtraction technique uses updation at both model generation phase and subtraction phase. The resultant video extracts the moving objects from the dynamic background. Sample videos of various properties such as cluttered background, small objects, moving background and multiple objects are considered for evaluation. The technique is statistically compared with frame differencing technique, temporal median method and mixture of Gaussian model and performance evaluation is done to check the effectiveness of the proposed technique after optimization for both static and dynamic videos.

  13. Evaluation of sacroiliitis: contrast-enhanced MRI with subtraction technique

    Energy Technology Data Exchange (ETDEWEB)

    Algin, Oktay; Gokalp, Gokhan; Baran, Bulent; Ocakoglu, Gokhan; Yazici, Zeynep [Uludag University, Medical Faculty, Department of Radiology, Gorukle, Bursa (Turkey)

    2009-10-15

    The purpose of the study was to investigate the diagnostic value of contrast-enhanced MRI using the subtraction technique in the detection of active sacroiliitis. Magnetic resonance imaging was performed in 8 asymptomatic volunteers and 50 patients with clinically suspected active sacroiliitis. On precontrast MR images, T1-weighted spin-echo images with and without fat saturation (T1WFS and T1W), STIR and 3D-FLASH images with fat saturation were obtained in the semicoronal plane using a 1.5 Tesla imager. Postcontrast MRI was performed using the same T1WFS sequence as before contrast injection for all volunteers and patients. Postcontrast images were subtracted from fat-suppressed precontrast images. Enhancement within the joint space and bone marrow was considered to demonstrate active sacroiliitis. In 50 patients (100 sacroiliac joints [SIJs]), 40 (76 SIJs) were considered to have active sacroiliitis based on MR images. Bone marrow edema was present in 33 patients (62 SIJs) on STIR images. Routine MRI allowed identification of contrast enhancement in SIJs on postcontrast T1WFS images in 31 patients (49 SIJs). Contrast enhancement was observed in 40 patients (76 SIJs) who were examined by MRI using the subtraction technique. Contrast enhancement was significantly more conspicuous on subtraction images than on non-subtracted postcontrast T1WFS images (Mann-Whitney U test, p<0.001). Contrast-enhanced MRI with subtraction technique may be useful for early detection of active sacroiliitis. (orig.)

  14. Interexaminer agreement in caries radiographic diagnosis by conventional and digital radiographs Avaliação interexaminadores no diagnóstico de cáries por meio de radiografias convencionais e digitais

    Directory of Open Access Journals (Sweden)

    Anna Sílvia Penteado Setti da Rocha

    2005-12-01

    Full Text Available The purpose of this research was to compare two digital storage phosphor systems and conventional film, as well as verify the interexaminer agreement in radiographic diagnosis on occlusal and proximal cavities. Two digital systems and conventional radiographic film were used to evaluate 144 tooth surfaces with and without cavities; the radiographs were analyzed and scored in a scale of 4 points. Thirteen undergraduates and an oral radiologist participated as examiners. A light microscopy analysis was accomplished in order to validate the research. The results showed that there was no significant difference between the radiographic systems, however all of them had significant differences when compared to light microscopy, except for the Digora system on the proximal surface when the radiologist was the examiner. In the interexaminer evaluation, a moderate agreement level was obtained, and a fair to moderate level was obtained between the students and the oral radiologist. Regarding the validation (sensitivity, specificity, positive predict and negative predict the values were similar between students and the oral radiologist, except for the sensitivity value on the occlusal surface. The students had the highest number of false-positive results and the oral radiologist the highest number of false-negative results.O objetivo desta pesquisa foi comparar dois sistemas digitais de armazenamento de fósforo e filme convencional, assim como verificar a concordância interexaminadores em diagnóstico radiográfico de cáries oclusais e proximais. Dois sistemas radiográficos digitais e filme convencional foram usados para avaliar 144 superfícies dentais com e sem cavitação; as radiografias foram analisadas e classificadas em uma escala de 4 pontos. Participaram como examinadores 13 alunos de graduação e um radiologista odontológico. Para validar esta pesquisa foram realizadas análises em microscopia ótica. Os resultados mostraram não haver

  15. The reliability and validity of measurements of human dental casts made by an intra-oral 3D scanner, with conventional hand-held digital callipers as the comparison measure.

    Science.gov (United States)

    Rajshekar, Mithun; Julian, Roberta; Williams, Anne-Marie; Tennant, Marc; Forrest, Alex; Walsh, Laurence J; Wilson, Gary; Blizzard, Leigh

    2017-09-01

    Intra-oral 3D scanning of dentitions has the potential to provide a fast, accurate and non-invasive method of recording dental information. The aim of this study was to assess the reliability of measurements of human dental casts made using a portable intra-oral 3D scanner appropriate for field use. Two examiners each measured 84 tooth and 26 arch features of 50 sets of upper and lower human dental casts using digital hand-held callipers, and secondly using the measuring tool provided with the Zfx IntraScan intraoral 3D scanner applied to the virtual dental casts. The measurements were repeated at least one week later. Reliability and validity were quantified concurrently by calculation of intra-class correlation coefficients (ICC) and standard errors of measurement (SEM). The measurements of the 110 landmark features of human dental casts made using the intra-oral 3D scanner were virtually indistinguishable from measurements of the same features made using conventional hand-held callipers. The difference of means as a percentage of the average of the measurements by each method ranged between 0.030% and 1.134%. The intermethod SEMs ranged between 0.037% and 0.535%, and the inter-method ICCs ranged between 0.904 and 0.999, for both the upper and the lower arches. The inter-rater SEMs were one-half and the intra-method/rater SEMs were one-third of the inter-method values. This study demonstrates that the Zfx IntraScan intra-oral 3D scanner with its virtual on-screen measuring tool is a reliable and valid method for measuring the key features of dental casts. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Digital Knowledge Resources

    Science.gov (United States)

    Pandian, M. Paul

    2008-01-01

    Technology has revolutionized the concept of libraries. Networking and computing technologies have now become sufficiently advanced to support the design and deployment of large digital libraries which are capable of supporting the conventional end-user functions. Digital libraries are a natural extension of the evolution in which libraries have…

  17. Digital Knowledge Resources

    Science.gov (United States)

    Pandian, M. Paul

    2008-01-01

    Technology has revolutionized the concept of libraries. Networking and computing technologies have now become sufficiently advanced to support the design and deployment of large digital libraries which are capable of supporting the conventional end-user functions. Digital libraries are a natural extension of the evolution in which libraries have…

  18. Digital automatic gain control

    Science.gov (United States)

    Uzdy, Z.

    1980-01-01

    Performance analysis, used to evaluated fitness of several circuits to digital automatic gain control (AGC), indicates that digital integrator employing coherent amplitude detector (CAD) is best device suited for application. Circuit reduces gain error to half that of conventional analog AGC while making it possible to automatically modify response of receiver to match incoming signal conditions.

  19. Construction and interpretation of a digital inertia image. [of Pisgah Crater and Lavic Lake in Southern California

    Science.gov (United States)

    Gillespie, A. R.; Kahle, A. B.

    1977-01-01

    An image representing the thermal inertia in the vicinity of Pisgah Crater and Lavic Lake in Southern California has been generated from visible, near IR, and thermal images taken from aircraft. Construction of the thermal inertia image required radiometric calibration and geometric rectification of the acquired images as well as registration to a topographic map. The Kahle thermal model used in the construction of the thermal inertia image requires specification of albedo, topographic slope and slope azimuth, diurnal temperature range and local meteorological conditions. Albedo information was derived from the visible image; digital topographic information was computed from digitized stereo aerial photographs; and thermal ranges were calculated by subtracting the predawn from the afternoon thermal image data. Our computed values of thermal inertia were in close agreement with published values for similar surface materials. Thermal inertia provides complementary information to conventional images of reflected solar radiation for use in lithologic mapping.

  20. Perancangan Papan Informasi Digital Berbasis Web pada Raspberry pi

    OpenAIRE

    Rizal Panuntun; Adian Fatchur Rochim; Kurniawan Teguh Martono

    2015-01-01

    Digital signage is information boards migrate from conventional forms to digital form. Form of digital signage used in computer by connecting to monitor to display the information. Digital notice board (digital signage) puts a digital-based information services in one direction. Many digital signage applications appear with the development of information technology. Unfortunately, if used as a digital signage devices, the implementation of existing digital signage applications using a desktop...

  1. Blind Source Separation Algorithms for PSF Subtraction from Direct Imaging

    Science.gov (United States)

    Shapiro, Jacob; Ranganathan, Nikhil; Savransky, Dmitry; Ruffio, Jean-Baptise; Macintosh, Bruce; GPIES Team

    2017-01-01

    The principal difficulty with detecting planets via direct imaging is that the target signal is similar in magnitude, or fainter, than the noise sources in the image. To compensate for this, several methods exist to subtract the PSF of the host star and other confounding noise sources. One of the most effective methods is Karhunen-Loève Image Processing (KLIP). The core algorithm within KLIP is Principal Component Analysis, which is a member of a class of algorithms called Blind Source Separation (BSS).We examine three other BSS algorithms that may potentially also be used for PSF subtraction: Independent Component Analysis, Stationary Subspace Analysis, and Common Spatial Pattern Filtering. The underlying principles of each of the algorithms is discussed, as well as the processing steps needed to achieve PSF subtraction. The algorithms are examined both as primary PSF subtraction techniques, as well as additional postprocessing steps used with KLIP.These algorithms have been used on data from the Gemini Planet Imager, analyzing images of β Pic b. To build a reference library, both Angular Differential Imaging and Spectral Differential Imaging were used. To compare to KLIP, three major metrics are examined: computation time, signal-to-noise ratio, and astrometric and photometric biases in different image regimes (e.g., speckle-dominated compared to Poisson-noise dominated). Preliminary results indicate that these BSS algorithms improve performance when used as an enhancement for KLIP, and that they can achieve similar SNR when used as the primary method of PSF subtraction.

  2. Appearance of the canine meninges in subtraction magnetic resonance images.

    Science.gov (United States)

    Lamb, Christopher R; Lam, Richard; Keenihan, Erin K; Frean, Stephen

    2014-01-01

    The canine meninges are not visible as discrete structures in noncontrast magnetic resonance (MR) images, and are incompletely visualized in T1-weighted, postgadolinium images, reportedly appearing as short, thin curvilinear segments with minimal enhancement. Subtraction imaging facilitates detection of enhancement of tissues, hence may increase the conspicuity of meninges. The aim of the present study was to describe qualitatively the appearance of canine meninges in subtraction MR images obtained using a dynamic technique. Images were reviewed of 10 consecutive dogs that had dynamic pre- and postgadolinium T1W imaging of the brain that was interpreted as normal, and had normal cerebrospinal fluid. Image-anatomic correlation was facilitated by dissection and histologic examination of two canine cadavers. Meningeal enhancement was relatively inconspicuous in postgadolinium T1-weighted images, but was clearly visible in subtraction images of all dogs. Enhancement was visible as faint, small-rounded foci compatible with vessels seen end on within the sulci, a series of larger rounded foci compatible with vessels of variable caliber on the dorsal aspect of the cerebral cortex, and a continuous thin zone of moderate enhancement around the brain. Superimposition of color-encoded subtraction images on pregadolinium T1- and T2-weighted images facilitated localization of the origin of enhancement, which appeared to be predominantly dural, with relatively few leptomeningeal structures visible. Dynamic subtraction MR imaging should be considered for inclusion in clinical brain MR protocols because of the possibility that its use may increase sensitivity for lesions affecting the meninges.

  3. Digital Batteries

    Science.gov (United States)

    Hubler, Alfred

    2009-03-01

    The energy density in conventional capacitors is limited by sparking. We present nano-capacitor arrays, where - like in laser diodes and quantum wells [1] - quantization prevents dielectric breakthrough. We show that the energy density and the power/weight ratio are very high, possibly larger than in hydrogen [2]. Digital batteries are a potential clean energy source for cars, laptops, and mobile devices. The technology is related to flash drives. However, because of the high energy density, safety is a concern. Digital batteries can be easily and safely charged and discharged. In the discharged state they pose no danger. Even if a charged digital battery were to explode, it would produce no radioactive waste, no long-term radiation, and probably could be designed to produce no noxious chemicals. We discuss methodologies to prevent shorts and other measures to make digital batteries safe. [1] H. Higuraskh, A. Toriumi, F. Yamaguchi, K. Kawamura, A. Hubler, Correlation Tunnel Device, U. S. Patent No. 5,679,961 (1997) [2] Alfred Hubler, http://server10.how-why.com/blog/

  4. Digital Radiation image

    Directory of Open Access Journals (Sweden)

    Abou-Bakr Ramadan

    2012-03-01

    Full Text Available This work introduces a new way for data visualization. Its name is Digital Application name' Image. Normal digital image is created by digital camera or digital scanner but digital application name image is created by measurements of monitoring data. This work uses the data which is measured by radiation monitoring station and classifies it using fuzzy logic rules to create digital radiation image. The main unique advantage of digital radiation image is that it expresses thousands of measurements in a very clear form through only one picture while the maximum number of measurements does not exceed 100 with other conventional visualization methods. This feature gives a facility to view one year of all recorded measurements in only one photo. This picture helps the user to observe the behavior of thousands of measurements in few minutes instead of spending few hours for reviewing hundreds of charts for the same measurements.

  5. Non-contrast-enhanced MR angiography in critical limb ischemia: performance of quiescent-interval single-shot (QISS) and TSE-based subtraction techniques

    Energy Technology Data Exchange (ETDEWEB)

    Altaha, Mustafa A. [University Health Network, Department of Medical Imaging, Peter Munk Cardiac Centre, Toronto, Ontario (Canada); Jaskolka, Jeffrey D.; Tan, Kongteng; Menezes, Ravi J. [University Health Network, Department of Medical Imaging, Peter Munk Cardiac Centre, Toronto, Ontario (Canada); University of Toronto, Department of Medical Imaging, Toronto, Ontario (Canada); Rick, Manuela; Schmitt, Peter [Siemens Healthcare, Erlangen (Germany); Wintersperger, Bernd J. [University Health Network, Department of Medical Imaging, Peter Munk Cardiac Centre, Toronto, Ontario (Canada); University of Toronto, Department of Medical Imaging, Toronto, Ontario (Canada); Toronto General Hospital, Department of Medical Imaging, Toronto, Ontario (Canada)

    2017-03-15

    The aim of this study was to evaluate diagnostic performance of non-contrast-enhanced 2D quiescent-interval single-shot (QISS) and 3D turbo spin-echo (TSE)-based subtraction magnetic resonance angiography (MRA) in the assessment of peripheral arteries in patients with critical limb ischemia (CLI). Nineteen consecutive patients (74 % male, 72.8 ± 9.9 years) with CLI underwent 2D QISS and 3D TSE-based subtraction MRA at 1.5 T. Axial-overlapping QISS MRA (3 mm/2 mm; 1 x 1 mm{sup 2}) covered from the toes to the aortic bifurcation while coronal 3D TSE-based subtraction MRA (1.3 x 1.2 x 1.3 mm{sup 3}) was restricted to the calf only. MRA data sets (two readers) were evaluated for stenosis (≥50 %) and image quality. Results were compared with digital subtraction angiography (DSA). Two hundred and sixty-seven (267) segments were available for MRA-DSA comparison, with a prevalence of stenosis ≥50 % of 41.9 %. QISS MRA was rated as good to excellent in 79.5-96.0 % of segments without any nondiagnostic segments; 89.8-96.1 % of segments in 3D TSE-based subtraction MRA were rated as nondiagnostic or poor. QISS MRA sensitivities and specificities (segmental) were 92 % and 95 %, respectively, for reader one and 81-97 % for reader two. Due to poor image quality of 3D TSE-based subtraction MRA, diagnostic performance measures were not calculated. QISS MRA demonstrates excellent diagnostic performance and higher robustness than 3D TSE-based subtraction MRA in the challenging patient population with CLI. (orig.)

  6. Optimized angiographic computed tomography with intravenous contrast injection: an alternative to conventional angiography in the follow-up of clipped aneurysms?

    Science.gov (United States)

    Gölitz, Philipp; Struffert, Tobias; Ganslandt, Oliver; Saake, Marc; Lücking, Hannes; Rösch, Julie; Knossalla, Frauke; Doerfler, Arnd

    2012-07-01

    The purpose of this study was to evaluate the diagnostic accuracy of an optimized angiographic CT (ACT) program with intravenous contrast agent injection (ivACT) in the assessment of potential aneurysm remnants after neurosurgical clipping compared with conventional digital subtraction angiography (DSA). The authors report on 14 patients with 19 surgically clipped cerebral aneurysms who were scheduled to undergo angiographic follow-up. For each patient, the authors performed ivACT with dual rotational acquisition and conventional angiography including a 3D rotational run. The ivACT and 3D DSA data were reconstructed with different imaging modes, including a newly implemented subtraction mode with motion correction. Thereafter, the data sets were merged by the dual-volume technique, and freely rotatable 3D images were obtained for further analysis. Observed aneurysm remnants were electronically measured and classified for each modality by 2 experienced neuroradiologists. Digital subtraction angiography and ivACT both provided high-quality images without motion artifacts. Artifact disturbances from the aneurysm clips led to a compromised, but still sufficient, image quality in 1 case. The ivACT assessed all aneurysm remnants as true-positive up to a minimal size of 2.6×2.4 mm in accordance with the DSA findings. There was a tendency for ivACT to overestimate the size of the aneurysm remnants. All cases without aneurysm remnants on DSA were scored correctly as true-negative by ivACT. By using an optimized image acquisition protocol as well as enhanced postprocessing algorithms, the noninvasive ivACT seems to achieve results comparable to those of conventional angiography in the follow-up of clipped cerebral aneurysms. The authors have shown that ivACT can provide reliable diagnostic information about potential aneurysm remnants after neurosurgical clipping with high sensitivity and specificity, sufficient for clinical decision making, at least for aneurysms in the

  7. pyKLIP: PSF Subtraction for Exoplanets and Disks

    Science.gov (United States)

    Wang, Jason J.; Ruffio, Jean-Baptise; De Rosa, Robert J.; Aguilar, Jonathan; Wolff, Schuyler G.; Pueyo, Laurent

    2015-06-01

    pyKLIP subtracts out the stellar PSF to search for directly-imaged exoplanets and disks using a Python implementation of the Karhunen-Loève Image Projection (KLIP) algorithm. pyKLIP supports ADI, SDI, and ADI+SDI to model the stellar PSF and offers a large array of PSF subtraction parameters to optimize the reduction. pyKLIP relies on a minimal amount of dependencies (numpy, scipy, and astropy) and parallelizes the KLIP algorithm to speed up the reduction. pyKLIP supports GPI and P1640 data and can interface with other data sources with the addition of new modules. It also can inject simulated planets and disks as well as automatically search for point sources in PSF-subtracted data.

  8. Proper image subtraction - optimal transient detection, photometry and hypothesis testing

    CERN Document Server

    Zackay, Barak; Gal-Yam, Avishay

    2016-01-01

    Transient detection and flux measurement via image subtraction stand at the base of time domain astronomy. Due to the varying seeing conditions, the image subtraction process is non-trivial, and existing solutions suffer from a variety of problems. Starting from basic statistical principles, we develop the optimal statistic for transient detection, flux measurement and any image-difference hypothesis testing. We derive a closed-form statistic that: (i) Is mathematically proven to be the optimal transient detection statistic in the limit of background-dominated noise; (ii) Is numerically stable; (iii) For accurately registered, adequately sampled images, does not leave subtraction or deconvolution artifacts; (iv) Allows automatic transient detection to the theoretical sensitivity limit by providing credible detection significance; (v) Has uncorrelated white noise; (vi) Is a sufficient statistic for any further statistical test on the difference image, and in particular, allows to distinguish particle hits and ...

  9. Accurate Sky Continuum Subtraction with Fibre-fed Spectrographs

    CERN Document Server

    Yang, Yanbin; Puech, Mathieu; Flores, Hector; Royer, Frederic; Disseau, Karen; Gonçalves, Thiago; Hammer, François; Cirasuolo, Michele; Evans, Chris; Causi, Gianluca Li; Maiolino, Roberto; Melo, Claudio

    2013-01-01

    Fibre-fed spectrographs now have throughputs equivalent to slit spectrographs. However, the sky subtraction accuracy that can be reached has often been pinpointed as one of the major issues associated with the use of fibres. Using technical time observations with FLAMES-GIRAFFE, two observing techniques, namely dual staring and cross beam-switching, were tested and the resulting sky subtraction accuracy reached in both cases was quantified. Results indicate that an accuracy of 0.6% on sky subtraction can be reached, provided that the cross beam-switching mode is used. This is very encouraging with regard to the detection of very faint sources with future fibre-fed spectrographs, such as VLT/MOONS or E-ELT/MOSAIC.

  10. Proposed smart integrated-optical preprocessor using holographic subtraction

    Science.gov (United States)

    Verber, C. M.; Vahey, D. W.

    1979-01-01

    The paper presents a proposed integrated-optical preprocessor with a holographic subtraction. It is based on an optical analog of a set of N analog voltages formed by passing an optical plane wave, confined in an electrooptic waveguide, under a set of N electrodes to which the voltages are applied; in the limit in which diffraction is ignored, the wavefront of the emerging guided wave will have superimposed upon it N discrete phase shifts. Processors which operate upon voltages encoded in this manner are being fabricated; they include a comparator in which incoming data are compared to a holographic record of the optical analog of a reference set, and a 'smart' system based upon holographic self-subtraction, in which the processor can independently adapt to changes in background information. The preprocessor operation is described in the screening, identification, and the self-subtraction modes, and implementation of devices in an integrated optical configuration is discussed.

  11. Construction of a metastasis-associated gene subtracted cDNA library of human colorectal carcinoma by suppression subtraction hybridization

    Institute of Scientific and Technical Information of China (English)

    Li Liang; Yan-Qing Ding; Xin Li; Guang-Zhi Yang; Jun Xiao; Li-Chun Lu; Jin-Hua Zhang

    2004-01-01

    AIM: To construct a differentially-expressed gene subtracted cDNA library from two colorectal carcinoma (CRC) cell lines with different metastatic phenotypes by suppression subtractive hybridization.METHODS: Two cell lines of human CRC from the same patient were used. SW620 cell line showing highly metastatic potential was regarded as tester in the forward subtractive hybridization, while SW480 cell line with lowly metastatic potential was treated as tester in the reverse hybridization. Suppression subtractive hybridization (SSH)was employed to obtain cDNA fragments of differentially expressed genes for the metastasis of CRC. These fragments were ligated with T vectors, screened through the bluewhite screening system to establish cDNA library.RESULTS: After the blue-white screening, 235 white clones were picked out from the positive-going hybridization and 232 from the reverse. PCR results showed that 200-700 bp inserts were seen in 98% and 91% clones from the forward and reverse hybridizations, respectively.CONCLUSIONS: A subtractive cDNA library of differentially expressed genes specific for metastasis of CRC can be constructed with SSH and T/A cloning techniques.

  12. Uso do levantamento aéreo expedito convencional e digital para o monitoramento da cobertura florestal no Paraná: estado da arte e potencialidades Conventional aerial sketchmapping and digital aerial sketchmapping development for forest monitoring in Paraná: state of art and potentialities

    Directory of Open Access Journals (Sweden)

    Fernando Luís Dlugosz

    2010-12-01

    defined the new name for the technique as Digital Aerial Sketchmapping. In this case the annotations are performed digitally on the screen (touch screen of a notebook and not on paper map, as in the conventional technique. The development of methodologies that demonstrate technical efficiency and economic viability has received increased emphasis on research, according to the necessity of obtaining reliable information to support decision making at the government level, for an appropriate monitoring procedure and/or planning a  given region. Considering the dynamics of land use and the need to monitor land cover, it can be stated that the Aerial Sketchmapping has high potential for application to brazilian conditions and still excelent cost/benefit relation.


    doi: 10.4336/2010.pfb.30.63.245

  13. Predictors of Morbidity and Cleavage Plane in Surgical Resection of Pure Convexity Meningiomas Using Cerebrospinal Fluid Sensitive Image Subtraction Magnetic Resonance Imaging

    Science.gov (United States)

    THENIER-VILLA, José LUIS; CAMPOVERDE, Raúl ALEJANDRO GALÁRRAGA; DE LA LAMA ZARAGOZA, Adolfo RAMÓN; ALONSO, Cesáreo CONDE

    2017-01-01

    Meningiomas are the most common primary intracranial tumors. Since the adhesions in the plane of dissection are of interest in surgical planning, we suggest that digital image subtraction of FLAIR data from the T2 sequence of MRI may represent better the CSF spaces in the brain–tumor interface and may be a predictor of the intraoperative cleavage plane. From 2006 to 2016, 83 convexity meningiomas were resected in the Department of Neurosurgery of the University Hospital Complex of Vigo, an analysis of preoperative MRI was performed to assess peritumoral edema (PTE), tumor volume, among others; a digital subtraction of T2-FLAIR sequences was performed and analyzed in relationship to the cleavage plane described in the intraoperative report and postoperative neurological deficits. Simpson grade 1 resection was achieved in 85.54%, the overall 5-year PFS was 93.75%. Our rate of permanent new neurological deficit was 4.82% and the overall complication rate of 14.46%. The grade of PTE was proportional to tumor volume, 20 ± 2.8, 30 ± 5.3, and 34 ± 4.3 cm3 for grades 1, 2, and 3, respectively, positive cleft sign on image subtraction was predictive of good intraoperative cleavage plane and low grade cleavage plane (P = 0.04), and was a protective factor for postoperative neurological deficit (P = 0.02). Positive cleft sign in T2-FLAIR digital subtraction image is an independent predictor of good intraoperative cleavage plane, PTE is an independent predictor of the bad cleavage plane. Negative cleft sign in the image subtraction and a bad intraoperative cleavage plane are predictors of postoperative neurological deficit. PMID:27580930

  14. Comparisons of FIR and IIR implementations of a subtraction-based stimulus artifact rejection algorithm.

    Science.gov (United States)

    Azin, Meysam; Chiel, Hillel J; Mohseni, Pedram

    2007-01-01

    Finite impulse response (FIR) and infinite impulse response (IIR) temporal filtering techniques are investigated to assess the feasibility of very-large-scale-integrated (VLSI) implementation of a subtraction-based stimulus artifact rejection (SAR) algorithm in implantable, closed-loop neuroprostheses. The two approaches are compared in terms of their system architectures, overall performances, and the associated computational costs. Pre-recorded neural data from an Aplysia californica are used to demonstrate the functionality of the proposed implementations. Digital building blocks for an FIR-based system are also simulated in a 0.18-microm CMOS technology, showing a total power consumption of IIR-based system can further reduce the required power consumption and die area.

  15. Quantitative analysis of alveolar bone change following implant placement using intraoral radiographic subtraction

    Energy Technology Data Exchange (ETDEWEB)

    Kimura, Hiroyuki; Kanda, Shigenobu [Kyushu Univ., Fukuoka (Japan). Graduate School of Dental Science; Tanaka, Takemasa [Kyushu Univ., Fukuoka (Japan). Dental Hospital

    2002-12-01

    The purpose of this study was to develop a procedure for quantitative analysis using intraoral radiographs of alveolar bone after placement of dental implants and to consider the validity of the method. We evaluated the ten patients (2 males and 8 females, average age: 48.4 years-old), who were treated with dental implant operation in the site of mandibular molar region, since October of 1999 until September of 2000 in Kimura Dental Clinic (Kumamoto, Japan). We evaluated the intraoral radiographs taken pre- and post- operatively and at follow-up examination. To detect alveolar bone change on radiograph, we adopted the digital subtraction method. Although the radiographs were taken under an ordinary technique with cone indicator, we did not apply the standardized technique with fixing material customized for each patient. Therefore, we used geometric correction and density compensation before subtraction. We assessed the basic statistical values (mean, variance, kurtosis and skewness) of the region of interest (ROI) of the subtracted images. Also, we noted PPD (probing pocket depth) and BOP (bleeding on probing) at each site as indicators of clinical findings and all implanted sites were classified according to the PPD or BOP, i.e. PPD increased group ''PPD (+)'' and PPD stable group ''PPD (-)'', likewise BOP positive group ''BOP (+)'' and negative group ''BOP (-)''. We considered the statistical values of ROI in each group and compared these findings. Mean and variance values of PPD (+) were higher than those of PPD (-) and there was a significant difference in mean value (p=0.031). Similarly, mean and variance values of BOP (+) were statistically higher than those of BOP (-) (p=0.041 and p=0.0087, respectively). Concerning kurtosis and skewness, there was no difference between PPD (+) and PPD (-), or between BOP (+) and BOP (-). Using our method, the radiographs taken for follow

  16. NULL Convention Floating Point Multiplier

    Directory of Open Access Journals (Sweden)

    Anitha Juliette Albert

    2015-01-01

    Full Text Available Floating point multiplication is a critical part in high dynamic range and computational intensive digital signal processing applications which require high precision and low power. This paper presents the design of an IEEE 754 single precision floating point multiplier using asynchronous NULL convention logic paradigm. Rounding has not been implemented to suit high precision applications. The novelty of the research is that it is the first ever NULL convention logic multiplier, designed to perform floating point multiplication. The proposed multiplier offers substantial decrease in power consumption when compared with its synchronous version. Performance attributes of the NULL convention logic floating point multiplier, obtained from Xilinx simulation and Cadence, are compared with its equivalent synchronous implementation.

  17. NULL convention floating point multiplier.

    Science.gov (United States)

    Albert, Anitha Juliette; Ramachandran, Seshasayanan

    2015-01-01

    Floating point multiplication is a critical part in high dynamic range and computational intensive digital signal processing applications which require high precision and low power. This paper presents the design of an IEEE 754 single precision floating point multiplier using asynchronous NULL convention logic paradigm. Rounding has not been implemented to suit high precision applications. The novelty of the research is that it is the first ever NULL convention logic multiplier, designed to perform floating point multiplication. The proposed multiplier offers substantial decrease in power consumption when compared with its synchronous version. Performance attributes of the NULL convention logic floating point multiplier, obtained from Xilinx simulation and Cadence, are compared with its equivalent synchronous implementation.

  18. Subtraction of beam-associated background in R measurement

    CERN Document Server

    Yan Wen Biao; Chi Shao Peng; Huang Guang Shun; Zhang Lei; Zhang Li; Zhao Zheng Gu; Dai Yu Mei; Li Hui; Wang Zhi Yong

    2002-01-01

    Using R scan data collected at BES II detector, the authors study the character of beam-associated background. The authors use the method of f factor and the fitting of event vertices to subtract the residual beam-associated background. The difference between the R values obtained by using these two methods is between 0.3% and 2.3%

  19. Addition and Subtraction by Students with Down Syndrome

    Science.gov (United States)

    Herrera, Aurelia Noda; Bruno, Alicia; Gonzalez, Carina; Moreno, Lorenzo; Sanabria, Hilda

    2011-01-01

    We present a research report on addition and subtraction conducted with Down syndrome students between the ages of 12 and 31. We interviewed a group of students with Down syndrome who executed algorithms and solved problems using specific materials and paper and pencil. The results show that students with Down syndrome progress through the same…

  20. "Abuelita" Epistemologies: Counteracting Subtractive Schools in American Education

    Science.gov (United States)

    Gonzales, Sandra M.

    2015-01-01

    This autoethnographic inquiry examines the intersection of elder epistemology and subtractive education, exploring how one "abuelita" countered her granddaughter's divestment of Mexican-ness. I demonstrate how the grandmother used "abuelita" epistemologies to navigate this tension and resist the assimilative pressures felt…

  1. Teaching Children about the Inverse Relation between Addition and Subtraction

    Science.gov (United States)

    Nunes, Terezinha; Bryant, Peter; Hallett, Darcy; Bell, Daniel; Evans, Deborah

    2009-01-01

    Two intervention studies are described. Both were designed to study the effects of teaching children about the inverse relation between addition and subtraction. The interventions were successful with 8-year-old children in Study 1 and to a limited extent with 5-year-old children in Study 2. In Study 1 teaching children about inversion increased…

  2. Addition and Subtraction by Students with Down Syndrome

    Science.gov (United States)

    Herrera, Aurelia Noda; Bruno, Alicia; Gonzalez, Carina; Moreno, Lorenzo; Sanabria, Hilda

    2011-01-01

    We present a research report on addition and subtraction conducted with Down syndrome students between the ages of 12 and 31. We interviewed a group of students with Down syndrome who executed algorithms and solved problems using specific materials and paper and pencil. The results show that students with Down syndrome progress through the same…

  3. Adding and Subtracting Vectors: The Problem with the Arrow Representation

    Science.gov (United States)

    Heckler, Andrew F.; Scaife, Thomas M.

    2015-01-01

    A small number of studies have investigated student understanding of vector addition and subtraction in generic or introductory physics contexts, but in almost all cases the questions posed were in the vector arrow representation. In a series of experiments involving over 1000 students and several semesters, we investigated student understanding…

  4. Fusion and subtraction post-processing in body MRI

    Energy Technology Data Exchange (ETDEWEB)

    Watson, Tom A.; Olsen, Oeystein E. [Great Ormond Street Hospital for Children NHS Foundation Trust, Department of Radiology, London (United Kingdom)

    2014-09-02

    Interpreting complex paediatric body MRI studies requires the integration of information from multiple sequences. Image processing software, some freely available, allows the radiologist to use simple and rapid post-processing techniques that may aid diagnosis. We demonstrate the use of fusion and subtraction post-processing techniques with examples from four areas of application: enterography, oncological imaging, musculoskeletal imaging and MR fistulography. (orig.)

  5. Children's Understanding of the Addition/Subtraction Complement Principle

    Science.gov (United States)

    Torbeyns, Joke; Peters, Greet; De Smedt, Bert; Ghesquière, Pol; Verschaffel, Lieven

    2016-01-01

    Background: In the last decades, children's understanding of mathematical principles has become an important research topic. Different from the commutativity and inversion principles, only few studies have focused on children's understanding of the addition/subtraction complement principle (if a - b = c, then c + b = a), mainly relying on verbal…

  6. Image Segmentation in Video Sequences Using Modified Background Subtraction

    Directory of Open Access Journals (Sweden)

    D. W. Chinchkhede

    2012-03-01

    Full Text Available In computer vision, "Background subtraction" is a technique for finding moving objects in a video sequences for example vehicle driving on a freeway. For to detect non stationary (dynamic objects, it is necessary to subtracting current image from a time-averaged background image. There are various background subtraction algorithms for detecting moving vehicles or any moving object(s like pedestrians in urban traffic video sequences. A crude approximation to the task of classifying each pixel on the frame of current image, locate slow-moving objects or in poor image qualities of videos and distinguish shadows from moving objects by using modified background subtraction method. While classifying each pixel on the frame of the current image, it is to be detect the moving object at foreground and background conditional environment that we can classify each pixel using a model of how that pixellooks when it is part of video frame classes. A mixture of Gaussians classification model for each pixel using an unsupervised technique is an efficient, incremental version of Expectation Maximization (EM is used for the purpose. Unlike standard image-averaging approach, this method automatically updates the mixture component for each video frame class according to likelihood of membership; hence slowmoving objects and poor image quality of videos are also being handled perfectly. Our approach identifies and eliminates shadows much more effectively than other techniques like thresholding.

  7. Subtraction-noise projection in gravitational-wave detector networks

    CERN Document Server

    Harms, Jan; Otto, Markus; Priess, Malte

    2008-01-01

    In this paper, we present a successful implementation of a subtraction-noise projection method into a simple, simulated data analysis pipeline of a gravitational-wave search. We investigate the problem to reveal a weak stochastic background signal which is covered by a strong foreground of compact-binary coalescences. The foreground which is estimated by matched filters, has to be subtracted from the data. Even an optimal analysis of foreground signals will leave subtraction noise due to estimation errors of template parameters which may corrupt the measurement of the background signal. The subtraction noise can be removed by a noise projection. We apply our analysis pipeline to the proposed future-generation space-borne Big Bang Observer (BBO) mission which seeks for a stochastic background of primordial GWs in the frequency range $\\sim 0.1-1 $Hz covered by a foreground of black-hole and neutron-star binaries. Our analysis is based on a simulation code which provides a dynamical model of a time-delay interfe...

  8. A method for dynamic subtraction MR imaging of the liver

    Directory of Open Access Journals (Sweden)

    Setti Ernesto

    2006-06-01

    Full Text Available Abstract Background Subtraction of Dynamic Contrast-Enhanced 3D Magnetic Resonance (DCE-MR volumes can result in images that depict and accurately characterize a variety of liver lesions. However, the diagnostic utility of subtraction images depends on the extent of co-registration between non-enhanced and enhanced volumes. Movement of liver structures during acquisition must be corrected prior to subtraction. Currently available methods are computer intensive. We report a new method for the dynamic subtraction of MR liver images that does not require excessive computer time. Methods Nineteen consecutive patients (median age 45 years; range 37–67 were evaluated by VIBE T1-weighted sequences (TR 5.2 ms, TE 2.6 ms, flip angle 20°, slice thickness 1.5 mm acquired before and 45s after contrast injection. Acquisition parameters were optimized for best portal system enhancement. Pre and post-contrast liver volumes were realigned using our 3D registration method which combines: (a rigid 3D translation using maximization of normalized mutual information (NMI, and (b fast 2D non-rigid registration which employs a complex discrete wavelet transform algorithm to maximize pixel phase correlation and perform multiresolution analysis. Registration performance was assessed quantitatively by NMI. Results The new registration procedure was able to realign liver structures in all 19 patients. NMI increased by about 8% after rigid registration (native vs. rigid registration 0.073 ± 0.031 vs. 0.078 ± 0.031, n.s., paired t-test and by a further 23% (0.096 ± 0.035 vs. 0.078 ± 0.031, p t-test after non-rigid realignment. The overall average NMI increase was 31%. Conclusion This new method for realigning dynamic contrast-enhanced 3D MR volumes of liver leads to subtraction images that enhance diagnostic possibilities for liver lesions.

  9. Left ventricular volume determined from scintigraphy and digital angiography by a semi-automated geometric method

    Energy Technology Data Exchange (ETDEWEB)

    Seldin, D.W.; Esser, P.D.; Nichols, A.B.; Ratner, S.J.; Alderson, P.O.

    1983-12-01

    The utility of a semi-automatic method of measuring left ventricular (LV) volume geometrically from gated blood-pool studies and digital subtraction angiography (DSA) was investigated using computerized edge detection and spatial calibration algorithms. LAO LV volumes determined from gated blood-pool studies were compared to volumes obtained from contrast left ventriculograms in 21 patients and the applicability of this method to DSA was evaluated in 25 additional patients who also had conventional left ventriculography. There was excellent correlation between the two, both for radionuclide studies and for DSA. Computer-based geometric determinations of LV volume appear to be rapid, accurate, and less dependent on subjective operator decisions than previously reported geometric approaches.

  10. Remedial Process for Negative Numbers Subtraction Operation: A Computerized Diagnostic Assessment

    Directory of Open Access Journals (Sweden)

    Elango Periasamy

    2012-01-01

    Full Text Available This study is a part of our research on remedial process for Negative Numbers subtraction operation. It was based on our previous study which involved 124 students aged 14 years old and five Mathematics teachers from secondary schools from a district in Malaysia which identified a diagnostic assessment for subject domain. It was found that conventionally to implement such diagnostic assessment in school setting was possible but the time and work load to analyse and make visual the misconceptions information was impossible as the sample size increases for mathematics teachers. Thus, this study was about computerization of that diagnostic assessment which would enable students to analyse their own ability in subject domain at anytime and anyplace. This system provides immediate analysis result which would save time and work load of remediation process and repeated as many times as each students wants to and be more responsible in monitoring their own misconception based on the analysis result obtained.

  11. Subtraction of Positive and Negative Numbers: The Difference and Completion Approaches with Chips

    Science.gov (United States)

    Flores, Alfinio

    2008-01-01

    Diverse contexts such as "take away," comparison," and "completion" give rise to subtraction problems. The take-away interpretation of subtraction has been explored using two-colored chips to help students understand addition and subtraction of integers. This article illustrates how the difference and completion (or missing addend) interpretations…

  12. Robust Background Subtraction with Foreground Validation for Urban Traffic Video

    Energy Technology Data Exchange (ETDEWEB)

    Cheung, S S; Kamath, C

    2004-01-15

    Identifying moving objects in a video sequence is a fundamental and critical task in many computer-vision applications. Background subtraction techniques are commonly used to separate foreground moving objects from the background. Most background subtraction techniques assume a single rate of adaptation, which is inadequate for complex scenes such as a traffic intersection where objects are moving at different and varying speeds. In this paper, we propose a foreground validation algorithm that first builds a foreground mask using a slow-adapting Kalman filter, and then validates individual foreground pixels by a simple moving object model, built using both the foreground and background statistics as well as the frame difference. Ground-truth experiments with urban traffic sequences show that our proposed algorithm significantly improves upon results using only Kalman filter or frame-differencing, and outperforms other techniques based on mixture of Gaussians, median filter, and approximated media filter.

  13. BBO and the Neutron-Star-Binary Subtraction Problem

    CERN Document Server

    Cutler, C

    2006-01-01

    The Big Bang Observer (BBO) is a proposed space-based gravitational-wave (GW) mission designed primarily to search for an inflation-generated GW background in the frequency range 0.1-1 Hz. The major astrophysical foreground in this range is gravitational radiation from inspiraling compact binaries. This foreground is expected to be much larger than the inflation-generated background, so to accomplish its main goal, BBO must be sensitive enough to identify and subtract out practically all such binaries in the observable universe. It is somewhat subtle to decide whether BBO's current baseline design is sufficiently sensitive for this task, since, at least initially, the dominant noise source impeding identification of any one binary is confusion noise from all the others. Here we present a self-consistent scheme for deciding whether BBO's baseline design is indeed adequate for subtracting out the binary foreground. We conclude that the current baseline should be sufficient. However if BBO's instrumental sensiti...

  14. Spinal pedicle subtraction osteotomy for fixed sagittal imbalance patients.

    Science.gov (United States)

    Hyun, Seung-Jae; Kim, Yongjung J; Rhim, Seung-Chul

    2013-11-16

    In addressing spinal sagittal imbalance through a posterior approach, the surgeon now may choose from among a variety of osteotomy techniques. Posterior column osteotomies such as the facetectomy or Ponte or Smith-Petersen osteotomy provide the least correction, but can be used at multiple levels with minimal blood loss and a lower operative risk. Pedicle subtraction osteotomies provide nearly 3 times the per-level correction of Ponte/Smith-Petersen osteotomies; however, they carry increased technical demands, longer operative time, and greater blood loss and associated significant morbidity, including neurological injury. The literature focusing on pedicle subtraction osteotomy for fixed sagittal imbalance patients is reviewed. The long-term overall outcomes, surgical tips to reduce the complications and suggestions for their proper application are also provided.

  15. ZAP -- Enhanced PCA Sky Subtraction for Integral Field Spectroscopy

    CERN Document Server

    Soto, Kurt T; Bacon, Roland; Richard, Johan; Conseil, Simon

    2016-01-01

    We introduce Zurich Atmosphere Purge (ZAP), an approach to sky subtraction based on principal component analysis (PCA) that we have developed for the Multi Unit Spectrographic Explorer (MUSE) integral field spectrograph. ZAP employs filtering and data segmentation to enhance the inherent capabilities of PCA for sky subtraction. Extensive testing shows that ZAP reduces sky emission residuals while robustly preserving the flux and line shapes of astronomical sources. The method works in a variety of observational situations from sparse fields with a low density of sources to filled fields in which the target source fills the field of view. With the inclusion of both of these situations the method is generally applicable to many different science cases and should also be useful for other instrumentation. ZAP is available for download at http://muse-vlt.eu/science/tools.

  16. Direct Imaging of Exoplanets Without Background Subtraction: Implications for ELTs

    CERN Document Server

    Frazin, Richard A

    2015-01-01

    The ultra-high contrast capability required to form images of other solar systems is arguably the highest-profile challenge in astronomy today. The current high-contrast imaging efforts all require background subtraction to separate the planetary image from the image of the host star. Background estimation is difficult due to the presence of non-common path aberrations (NCPAs) that change with time. The only major source of information that is not being utilized by current efforts is the random encoding of the planetary image and the NCPAs by the atmosphere on millisecond time-scales. Here, a method that utilizes this information in order to avoid background subtraction altogether is proposed. This new paradigm will allow simultaneous estimation of the time-dependent NCPAs and the planetary image via rigorous statistical inference procedures. These procedures are fully compatible with other information sources, such as diurnal field rotation and spectral diversity. Given the open-ended nature of the backgroun...

  17. An Adaptive Background Subtraction Method Based on Kernel Density Estimation

    Directory of Open Access Journals (Sweden)

    Mignon Park

    2012-09-01

    Full Text Available In this paper, a pixel-based background modeling method, which uses nonparametric kernel density estimation, is proposed. To reduce the burden of image storage, we modify the original KDE method by using the first frame to initialize it and update it subsequently at every frame by controlling the learning rate according to the situations. We apply an adaptive threshold method based on image changes to effectively subtract the dynamic backgrounds. The devised scheme allows the proposed method to automatically adapt to various environments and effectively extract the foreground. The method presented here exhibits good performance and is suitable for dynamic background environments. The algorithm is tested on various video sequences and compared with other state-of-the-art background subtraction methods so as to verify its performance.

  18. Momentum-subtraction renormalization techniques in curved space-time

    Energy Technology Data Exchange (ETDEWEB)

    Foda, O.

    1987-10-01

    Momentum-subtraction techniques, specifically BPHZ and Zimmermann's Normal Product algorithm, are introduced as useful tools in the study of quantum field theories in the presence of background fields. In a model of a self-interacting massive scalar field, conformally coupled to a general asymptotically-flat curved space-time with a trivial topology, momentum-subtractions are shown to respect invariance under general coordinate transformations. As an illustration, general expressions for the trace anomalies are derived, and checked by explicit evaluation of the purely gravitational contributions in the free field theory limit. Furthermore, the trace of the renormalized energy-momentum tensor is shown to vanish at the Gell-Mann Low eigenvalue as it should.

  19. The change of radiation doses to the patient when switching from conventional technique to digital technique without films in barium enema and IVU examinations. Final report SSI research project P933

    CERN Document Server

    Sjöholm, B

    2003-01-01

    X-ray examinations of the colon (barium enema) and the kidneys (IVU) are combined with rather high radiation doses to the patients when using analogue technique with film-screen systems. It is therefore of great interest to see if the change from analogue to digital technique involves a reduction of doses. Barium enema and IVU examinations were monitored with DAP-meters before and after the X-ray department changed to digital techniques. For IVU also the change from storage phosphor plates to a Direct Digital detector is included. The study comprises between 53 and 87 patients for each modality of the two examinations. A considerable dose reduction was observed. In barium enema the overview images with large field sizes were omitted when using digital technique. On the other hand the number of spot images was increased from 6 to 22. The fluoroscopy time was increased from 4 minutes to 6 minutes. The DAP value was reduced from 54,3 Gy cm sup 2 to 21,9 Gy cm sup 2. For IVU a dose reduction from 44,5 Gy cm sup 2...

  20. Digital Information and Value

    Directory of Open Access Journals (Sweden)

    Paul Walton

    2015-11-01

    Full Text Available Digital information changes the ways in which people and organisations interact. This paper examines the nature of this change in the context of the author’s Model for Information (MfI. It investigates the relationship between outcomes and value, selection processes and some attributes of information and explores how this relationship changes in the move from analogue to digital information. Selection processes shape the evolution of information ecosystems in which conventions are established for the ways in which information is used. The conventions determine norms for information friction and information quality as well as the sources of information and channels used. Digital information reduces information friction, often dramatically, and changes information quality. The increasing use of analytics in business increasingly delivers predictive or prescriptive digital information. These changes are happening faster than information ecosystem conventions can change. The relationships established in the paper enable an analysis of, and guide changes to, these conventions enabling a more effective use of digital information.

  1. Increasing entanglement between Gaussian states by coherent photon subtraction.

    Science.gov (United States)

    Ourjoumtsev, Alexei; Dantan, Aurélien; Tualle-Brouri, Rosa; Grangier, Philippe

    2007-01-19

    We experimentally demonstrate that the entanglement between Gaussian entangled states can be increased by non-Gaussian operations. Coherent subtraction of single photons from Gaussian quadrature-entangled light pulses, created by a nondegenerate parametric amplifier, produces delocalized states with negative Wigner functions and complex structures more entangled than the initial states in terms of negativity. The experimental results are in very good agreement with the theoretical predictions.

  2. Increasing entanglement between Gaussian states by coherent photon subtraction

    CERN Document Server

    Ourjoumtsev, A; Tualle-Brouri, R; Grangier, P; Ourjoumtsev, Alexei; Dantan, Aurelien; Tualle-Brouri, Rosa; Grangier, Philippe

    2006-01-01

    We experimentally demonstrate that the entanglement between Gaussian entangled states can be increased by non-Gaussian operations. Coherent subtraction of single photons from Gaussian quadrature-entangled light pulses, created by a non-degenerate parametric amplifier, produces delocalized "Schroedinger kitten" states with complex negative Wigner functions, more entangled than the initial states in terms of negativity. The experimental results are in very good agreement with the theoretical predictions.

  3. Manufacturability analysis to combine additive and subtractive processes

    OpenAIRE

    Kerbrat, Olivier; MOGNOL, Pascal; Hascoët, Jean-Yves

    2010-01-01

    International audience; Purpose - The purpose of this paper is to propose a methodology to estimate manufacturing complexity for both machining and layered manufacturing. The goal is to take into account manufacturing constraints at design stage in order to realize tools (dies and molds) by a combination of a subtractive process (high-speed machining) and an additive process (selective laser sintering). Design/methodology/approach - Manufacturability indexes are defined and calculated from th...

  4. Manufacturability analysis to combine additive and subtractive processes

    OpenAIRE

    Kerbrat, Olivier; Mognol, Pascal; Hascoët, Jean-Yves

    2010-01-01

    International audience; Purpose - The purpose of this paper is to propose a methodology to estimate manufacturing complexity for both machining and layered manufacturing. The goal is to take into account manufacturing constraints at design stage in order to realize tools (dies and molds) by a combination of a subtractive process (high-speed machining) and an additive process (selective laser sintering). Design/methodology/approach - Manufacturability indexes are defined and calculated from th...

  5. Subtractive Renormalization Group Invariance: Pionless EFT at NLO

    Science.gov (United States)

    Timóteo, Varese S.; Szpigel, Sérgio; Durães, Francisco O.

    2010-11-01

    We show some results concerning the renormalization group (RG) invariance of the nucleon-nucleon (NN) interaction in pionless effective field theory at next-to-leading order (NLO), using a non-relativistic Callan-Symanzik equation (NRCS) for the driving term of the Lippmann-Schwinger (LS) equation with three recursive subtractions. The phase-shifts obtained for the RG evolved potential are same as those for the original potential, apart from relative differences of order 10-15.

  6. ROBUST TECHNIQUES FOR BACKGROUND SUBTRACTION IN URBAN TRAFFIC VIDEO

    Energy Technology Data Exchange (ETDEWEB)

    Kamath, C; Cheung, S S

    2003-10-28

    Identifying moving objects from a video sequence is a fundamental and critical task in many computer-vision applications. A common approach is to perform background subtraction, which identifies moving objects from the portion of a video frame that differs significantly from a background model. There are many challenges in developing a good background subtraction algorithm. First, it must be robust against changes in illumination. Second, it should avoid detecting non-stationary background objects such as swinging leaves, rain, snow, and shadow cast by moving objects. Finally, its internal background model should react quickly to changes in background such as starting and stopping of vehicles. In this paper, we compare various background subtraction algorithms for detecting moving vehicles and pedestrians in urban traffic video sequences. We consider approaches varying from simple techniques such as frame differencing and adaptive median filtering, to more sophisticated probabilistic modeling techniques. While complicated techniques often produce superior performance, our experiments show that simple techniques such as adaptive median filtering can produce good results with much lower computational complexity.

  7. N-jettiness Subtractions for NNLO QCD Calculations

    CERN Document Server

    Gaunt, Jonathan; Tackmann, Frank J; Walsh, Jonathan R

    2015-01-01

    We present a subtraction method utilizing the N-jettiness observable, Tau_N, to perform QCD calculations for arbitrary processes at next-to-next-to-leading order (NNLO). Our method employs soft-collinear effective theory (SCET) to determine the IR singular contributions of N-jet cross sections for Tau_N -> 0, and uses these to construct suitable Tau_N-subtractions. The construction is systematic and economic, due to being based on a physical observable. The resulting NNLO calculation is fully differential and in a form directly suitable for combining with resummation and parton showers. We explain in detail the application to processes with an arbitrary number of massless partons at lepton and hadron colliders together with the required external inputs in the form of QCD amplitudes and lower-order calculations. We provide explicit expressions for the Tau_N-subtractions at NLO and NNLO. The required ingredients are fully known at NLO, and at NNLO for processes with two external QCD partons. The remaining NNLO ...

  8. Addition and subtraction in wild New Zealand robins.

    Science.gov (United States)

    Garland, Alexis; Low, Jason

    2014-11-01

    This experiment aimed to investigate proto-arithmetic ability in a wild population of New Zealand robins. We investigated numerical competence from the context of computation: behavioural responses to arithmetic operations over small numbers of prey objects (mealworms). Robins' behavioural responses (such as search time) to the simple addition and subtraction problems presented in a Violation of Expectancy (VoE) paradigm were measured. Either a congruent (expected) or incongruent (unexpected) quantity of food items were hidden in a trap door out of view of the subject. Within view of the subject, a quantity of items were added into (and in some cases subtracted from) the apparatus which was either the same as that hidden, or different. Robins were then allowed them to find a quantity that either preserved or violated addition and subtraction outcomes. Robins searched around the apparatus longer when presented with an incongruent scenario violating arithmetic rules, demonstrating potential proto-arithmetic awareness of changes in prey quantity. This article is part of a Special Issue entitled: Cognition in the wild.

  9. Genome subtraction for novel target definition in Salmonella typhi.

    Science.gov (United States)

    Rathi, Bhawna; Sarangi, Aditya N; Trivedi, Nidhi

    2009-10-11

    Large genomic sequencing projects of pathogens as well as human genome leads to immense genomic and proteomic data which would be very beneficial for the novel target identification in pathogens. Subtractive genomic approach is one of the most useful strategies helpful in identification of potential targets. The approach works by subtracting the genes or proteins homologous to both host and the pathogen and identify those set of gene or proteins which are essential for the pathogen and are exclusively present in the pathogen. Subtractive genomic approach is employed to identify novel target in salmonella typhi. The pathogen has 4718 proteins out of which 300 are found to be essential (" indispensable to support cellular life") in the pathogen with no human homolog. Metabolic pathway analyses of these 300 essential proteins revealed that 149 proteins are exclusively involved in several metabolic pathway of S. typhi. 8 metabolic pathways are found to be present exclusively in the pathogen comprising of 27 enzymes unique to the pathogen. Thus, these 27 proteins may serve as prospective drug targets. Sub-cellular localization prediction of the 300 essential proteins was done which reveals that 11 proteins lie on the outer membrane of the pathogen which could be probable vaccine candidates.

  10. Análise comparativa da maturação óssea determinada pelo método de Grave-Brown entre imagens convencionais e digitalizadas Comparative analysis of bone maturation determined by Grave-Brown method in conventional and digitalized images

    Directory of Open Access Journals (Sweden)

    Marcia Spinelli Casanova

    2006-10-01

    Full Text Available OBJETIVO: o presente estudo teve como objetivo comparar os estágios de maturação óssea estimados pelo método de Grave-Brown em radiografias de mão e punho convencionais e digitalizadas. METODOLOGIA: a amostra foi composta por 129 radiografias de mão e punho de indivíduos brasileiros do gênero feminino, com idades cronológicas entre 84 e 199 meses. As radiografias foram digitalizadas e posteriormente analisadas por cinco observadores. RESULTADOS E CONCLUSÃO: os resultados mostraram que não houve diferença estatisticamente significante entre os estágios de maturação óssea estimados, tanto nas imagens radiográficas convencionais como nas digitalizadas. Verificou-se ainda a reprodutibilidade dos observadores, sendo o valor de Kappa de 0,86 para as imagens convencionais e de 0,87 para as imagens digitalizadas. Recomenda-se a utilização de imagens digitalizadas como uma alternativa à imagem convencional para estimar a maturação óssea em radiografias de mão e punho.AIM: the purpose of the present study was to compare the skeletal maturation stages estimated using the method of Grave-Brown in conventional and digitalized hand and wrist x-rays. METHODS: the sample was composed by 129 hand and wrist radiographs of Brazilian girls, with chronological ages between 84 and 199 months. The radiographs were digitalized and analyzed by five observers. RESULTS AND CONCLUSION: the results showed no statistically significant difference between the skeletal maturation stages estimated in the conventional or the digitalized images by Grave-Brown’s method. The reproducibility of the observers was also verified, the value of Kappa was 0.86 for the conventional images and 0.87 for the digitalized images. Therefore digitalized images are a reliable alternative for skeletal maturation estimation.

  11. An improved dark-object subtraction technique for atmospheric scattering correction of multispectral data

    Science.gov (United States)

    Chavez, P.S.

    1988-01-01

    Digital analysis of remotely sensed data has become an important component of many earth-science studies. These data are often processed through a set of preprocessing or "clean-up" routines that includes a correction for atmospheric scattering, often called haze. Various methods to correct or remove the additive haze component have been developed, including the widely used dark-object subtraction technique. A problem with most of these methods is that the haze values for each spectral band are selected independently. This can create problems because atmospheric scattering is highly wavelength-dependent in the visible part of the electromagnetic spectrum and the scattering values are correlated with each other. Therefore, multispectral data such as from the Landsat Thematic Mapper and Multispectral Scanner must be corrected with haze values that are spectral band dependent. An improved dark-object subtraction technique is demonstrated that allows the user to select a relative atmospheric scattering model to predict the haze values for all the spectral bands from a selected starting band haze value. The improved method normalizes the predicted haze values for the different gain and offset parameters used by the imaging system. Examples of haze value differences between the old and improved methods for Thematic Mapper Bands 1, 2, 3, 4, 5, and 7 are 40.0, 13.0, 12.0, 8.0, 5.0, and 2.0 vs. 40.0, 13.2, 8.9, 4.9, 16.7, and 3.3, respectively, using a relative scattering model of a clear atmosphere. In one Landsat multispectral scanner image the haze value differences for Bands 4, 5, 6, and 7 were 30.0, 50.0, 50.0, and 40.0 for the old method vs. 30.0, 34.4, 43.6, and 6.4 for the new method using a relative scattering model of a hazy atmosphere. ?? 1988.

  12. Non-contrast-enhanced MR angiography in critical limb ischemia: performance of quiescent-interval single-shot (QISS) and TSE-based subtraction techniques.

    Science.gov (United States)

    Altaha, Mustafa A; Jaskolka, Jeffrey D; Tan, Kongteng; Rick, Manuela; Schmitt, Peter; Menezes, Ravi J; Wintersperger, Bernd J

    2017-03-01

    The aim of this study was to evaluate diagnostic performance of non-contrast-enhanced 2D quiescent-interval single-shot (QISS) and 3D turbo spin-echo (TSE)-based subtraction magnetic resonance angiography (MRA) in the assessment of peripheral arteries in patients with critical limb ischemia (CLI). Nineteen consecutive patients (74 % male, 72.8 ± 9.9 years) with CLI underwent 2D QISS and 3D TSE-based subtraction MRA at 1.5 T. Axial-overlapping QISS MRA (3 mm/2 mm; 1 × 1 mm(2)) covered from the toes to the aortic bifurcation while coronal 3D TSE-based subtraction MRA (1.3 × 1.2 × 1.3 mm(3)) was restricted to the calf only. MRA data sets (two readers) were evaluated for stenosis (≥50 %) and image quality. Results were compared with digital subtraction angiography (DSA). Two hundred and sixty-seven (267) segments were available for MRA-DSA comparison, with a prevalence of stenosis ≥50 % of 41.9 %. QISS MRA was rated as good to excellent in 79.5-96.0 % of segments without any nondiagnostic segments; 89.8-96.1 % of segments in 3D TSE-based subtraction MRA were rated as nondiagnostic or poor. QISS MRA sensitivities and specificities (segmental) were 92 % and 95 %, respectively, for reader one and 81-97 % for reader two. Due to poor image quality of 3D TSE-based subtraction MRA, diagnostic performance measures were not calculated. QISS MRA demonstrates excellent diagnostic performance and higher robustness than 3D TSE-based subtraction MRA in the challenging patient population with CLI. • QISS MRA allows reliable diagnosis of peripheral artery stenosis in critical limb ischemia. • Robustness of TSE-based subtraction MRA is limited in critical limb ischemia. • QISS MRA allows robust therapy planning in PAD patients with resting leg pain.

  13. Digital X-ray Imaging in Dentistry

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Eun Kyung [Dept. of Oral and Maxillofacial Radiology, College of Dentistry, Dankook University, Yongin (Korea, Republic of)

    1999-08-15

    In dentistry, Radio Visio Graphy was introduced as a first electronic dental x-ray imaging modality in 1989. Thereafter, many types of direct digital radiographic systems have been produced in the last decade. They are based either on charge-coupled device (CCD) or on storage phosphor technology. In addition, new types of digital radiographic system using amorphous selenium, image intensifier etc. are under development. Advantages of digital radiographic system are elimination of chemical processing, reduction in radiation dose, image processing, computer storage, electronic transfer of images and so on. Image processing includes image enhancement, image reconstruction, digital subtraction, etc. Especially digital subtraction and reconstruction can be applied in many aspects of clinical practice and research. Electronic transfer of images enables filmless dental hospital and teleradiology/teledentistry system. Since the first image management and communications system (IMACS) for dentomaxillofacial radiology was reported in 1992, IMACS in dental hospital has been increasing. Meanwhile, researches about computer-assisted diagnosis, such as structural analysis of bone trabecular patterns of mandible, feature extraction, automated identification of normal landmarks on cephalometric radiograph and automated image analysis for caries or periodontitis, have been performed actively in the last decade. Further developments in digital radiographic imaging modalities, image transmission system, imaging processing and automated analysis software will change the traditional clinical dental practice in the 21st century.

  14. Digital Publishing: Imperfect, but Improving

    Science.gov (United States)

    Boettcher, Judith V.

    2007-01-01

    Digital publishing is a field lurching along many paths and alleyways of experimentation. For their potential influence, however, recent approaches bear watching. In this article, the author shares the story of Jason on his personal decision-making struggles on using digital versions against conventional textbooks. The author also discusses…

  15. Digital Textbooks. Research Brief

    Science.gov (United States)

    Johnston, Howard

    2011-01-01

    Despite their growing popularity, digital alternatives to conventional textbooks are stirring up controversy. With the introduction of tablet computers, and the growing trend toward "cloud computing" and "open source" software, the trend is accelerating because costs are coming down and free or inexpensive materials are becoming more available.…

  16. Adding and subtracting vectors: The problem with the arrow representation

    Directory of Open Access Journals (Sweden)

    Andrew F. Heckler

    2015-01-01

    Full Text Available A small number of studies have investigated student understanding of vector addition and subtraction in generic or introductory physics contexts, but in almost all cases the questions posed were in the vector arrow representation. In a series of experiments involving over 1000 students and several semesters, we investigated student understanding of vector addition and subtraction in both the arrow and algebraic notation (using i[over ^], j[over ^], k[over ^] in generic mathematical and physics contexts. First, we replicated a number of previous findings of student difficulties in the arrow format and discovered several additional difficulties, including the finding that different relative arrow orientations can prompt different solution paths and different kinds of mistakes, which suggests that students need to practice with a variety of relative orientations. Most importantly, we found that average performance in the ijk format was typically excellent and often much better than performance in the arrow format in either the generic or physics contexts. Further, while we find that the arrow format tends to prompt students to a more physically intuitive solution path, we also find that, when prompted, student solutions in the ijk format also display significant physical insights into the problem. We also find a hierarchy in correct answering between the two formats, with correct answering in the ijk format being more fundamental than for the arrow format. Overall, the results suggest that many student difficulties with these simple vector problems lie with the arrow representation itself. For instruction, these results imply that introducing the ijk notation (or some equivalent with the arrow notation concurrently may be a very useful way to improve student performance as well as help students to learn physics concepts involving vector addition and subtraction.

  17. Leading Guard Digits in Finite-Precision Redundant Representations

    OpenAIRE

    Muller, Jean-Michel; Kornerup, Peter

    2006-01-01

    Redundant number representations are generally used to allow constant time additions, based on the fact that only bounded carry-ripples take place. But, carries may ripple out into positions which may not be needed to represent the final value of the result and, thus, a certain amount of leading guard digits are needed to correctly determine the result. Also, when cancellation during subtractions occurs, there may be nonzero digits in positions not needed to represent the result of the calcul...

  18. Intermediate Palomar Transient Factory: Realtime Image Subtraction Pipeline

    CERN Document Server

    Cao, Yi; Kasliwal, Mansi M

    2016-01-01

    A fast-turnaround pipeline for realtime data reduction plays an essential role in discovering and permitting follow-up observations to young supernovae and fast-evolving transients in modern time-domain surveys. In this paper, we present the realtime image subtraction pipeline in the intermediate Palomar Transient Factory. By using high-performance computing, efficient database, and machine learning algorithms, this pipeline manages to reliably deliver transient candidates within ten minutes of images being taken. Our experience in using high performance computing resources to process big data in astronomy serves as a trailblazer to dealing with data from large-scale time-domain facilities in near future.

  19. Addition and subtraction by students with Down syndrome

    Science.gov (United States)

    Noda Herrera, Aurelia; Bruno, Alicia; González, Carina; Moreno, Lorenzo; Sanabria, Hilda

    2011-01-01

    We present a research report on addition and subtraction conducted with Down syndrome students between the ages of 12 and 31. We interviewed a group of students with Down syndrome who executed algorithms and solved problems using specific materials and paper and pencil. The results show that students with Down syndrome progress through the same procedural levels as those without disabilities though they have difficulties in reaching the most abstract level (numerical facts). The use of fingers or concrete representations (balls) appears as a fundamental process among these students. As for errors, these vary widely depending on the students, and can be attributed mostly to an incomplete knowledge of the decimal number system.

  20. Black hole entropy thermodynamics, statistical-mechanics and subtraction procedure

    CERN Document Server

    Frolov, V P; Zelnikov, A I

    1996-01-01

    The thermodynamical one-loop entropy S^{TD} of a two-dimensional black hole in thermal equilibrium with the massless quantum gas is calculated. It is shown that S^{TD} includes the Bekenstein-Hawking entropy, evaluated for the quantum corrected geometry, and the finite difference of statistical mechanical entropies -Tr\\hat{\\rho}\\ln\\hat{\\rho} for the gas on the black hole and Rindler spaces. This result demonstrates in an explicit form that the relation between thermodynamical and statistical-mechanical entropies of a black hole is non-trivial and requires special subtraction procedure.

  1. Subtracting Technique of Baselines for Capillary Electrophoresis Signals

    Institute of Scientific and Technical Information of China (English)

    WANG Ying; MO Jin-yuan; CHEN Zuan-guang; GAO Yan

    2004-01-01

    The drifting baselines of capillary electrophoresis affect the veracity of analysis greatly. This paper presents Threshold Fitting Technique(TFT) so as to subtract the baselines from the original signals and emendate the signals. In TFT, wav elet and curve fitting technique are applied synthetically, thresholds are decided by the computer automatically. Many experiments of signal processing indicate that TFT is simple for being used, there are few man-induced factors, and the results are satisfactory. TFT can be applied for noisy signals without any pre-processing.

  2. [Ziedses des Plantes: inventor of planigraphy and subtraction].

    Science.gov (United States)

    van Gijn, Jan; Gijselhart, Joost P

    2011-01-01

    Bernard George Ziedses des Plantes (1902-1993) trained in Utrecht, the Netherlands, as specialist in nervous diseases, but his lifelong passion was to improve X-ray imaging of living tissues. In the 1930s he not only built the first machine for planigraphy, in which the X-ray tube and the film moved together around the plane of interest, but he also designed the subtraction method to improve images after injection of contrast agents. Eventually a full-time radiologist, he also developed the 'somersault' technique of ventriculography and pioneered isotope scintigraphy.

  3. Comparing Background Subtraction Algorithms and Method of Car Counting

    CERN Document Server

    Thakur, Gautam S; Hui, Pan; Helmy, Ahmed

    2012-01-01

    In this paper, we compare various image background subtraction algorithms with the ground truth of cars counted. We have given a sample of thousand images, which are the snap shots of current traffic as records at various intersections and highways. We have also counted an approximate number of cars that are visible in these images. In order to ascertain the accuracy of algorithms to be used for the processing of million images, we compare them on many metrics that includes (i) Scalability (ii) Accuracy (iii) Processing time.

  4. Speech enhancement by array crosstalk resistant ANC and spectrum subtraction

    Institute of Scientific and Technical Information of China (English)

    ZENG Qingning; OUYANG Shan

    2008-01-01

    Microphone array-based speech enhancement has great importance for speech com-munications and speech recognition. To reduce the aperture of the microphone array and to increase the effect of the speech enhancement will greatly broaden the application areas of the microphone array. An array crosstalk resistant adaptive noise cancellation method is therefore presented. And then an improved spectral subtraction algorithm is further cascaded to obtain better enhancement results. Theoretic analysis and experiments indicate that the proposed scheme needs only a very small microphone array while it simultaneously achieves a higher SNR improvement. Besides, the proposed scheme can be used in many noisy environments and is easy for real-time implementation.

  5. Development of a voxel-matching technique for substantial reduction of subtraction artifacts in temporal subtraction images obtained from thoracic MDCT.

    Science.gov (United States)

    Itai, Yoshinori; Kim, Hyoungseop; Ishikawa, Seiji; Katsuragawa, Shigehiko; Doi, Kunio

    2010-02-01

    A temporal subtraction image, which is obtained by subtraction of a previous image from a current one, can be used for enhancing interval changes (such as formation of new lesions and changes in existing abnormalities) on medical images by removing most of the normal structures. However, subtraction artifacts are commonly included in temporal subtraction images obtained from thoracic computed tomography and thus tend to reduce its effectiveness in the detection of pulmonary nodules. In this study, we developed a new method for substantially removing the artifacts on temporal subtraction images of lungs obtained from multiple-detector computed tomography (MDCT) by using a voxel-matching technique. Our new method was examined on 20 clinical cases with MDCT images. With this technique, the voxel value in a warped (or nonwarped) previous image is replaced by a voxel value within a kernel, such as a small cube centered at a given location, which would be closest (identical or nearly equal) to the voxel value in the corresponding location in the current image. With the voxel-matching technique, the correspondence not only between the structures but also between the voxel values in the current and the previous images is determined. To evaluate the usefulness of the voxel-matching technique for removal of subtraction artifacts, the magnitude of artifacts remaining in the temporal subtraction images was examined by use of the full width at half maximum and the sum of a histogram of voxel values, which may indicate the average contrast and the total amount, respectively, of subtraction artifacts. With our new method, subtraction artifacts due to normal structures such as blood vessels were substantially removed on temporal subtraction images. This computerized method can enhance lung nodules on chest MDCT images without disturbing misregistration artifacts.

  6. The Hague Judgments Convention

    DEFF Research Database (Denmark)

    Nielsen, Peter Arnt

    2011-01-01

    The Hague Judgments Convention of 2005 is the first global convention on international jurisdiction and recognition and enforcement of judgments in civil and commercial matters. The author explains the political and legal background of the Convention, its content and certain crucial issues during...

  7. Bio-Nanofabrication: Structuring Polymer Thin Films via Bacterial S-layer Proteins for Subsequent Use with Subtractive Nanofabrication Techniques

    Science.gov (United States)

    Esch, Mandy B.; Amponsah, Ebenezer K.; Bergkvist, Magnus

    2007-03-01

    Bio-molecule assisted lithography is a novel approach to create ordered patterns on the micro and nanometer size scale on thin films. The technique bears the potential to utilize self assembling properties of bio-molecules and to be integrated with conventional nanofabrication techniques. In the past, bacterial cell wall proteins (S-layers proteins) have been utilized to create ordered nanoparticle arrays. The work presented here employs S-layer proteins to shape UV-curable resist via an S-layer imprinted parylene template. Using this technique we can replicate S-layer patterns in resist thereby rendering the shape more resistant to subtractive nanofabrication techniques. The technique also demonstrates the adequacy of Nano Imprint Lithography to produce complex patterns not achievable with conventional lithography.

  8. Indexing, Browsing, and Searching of Digital Video.

    Science.gov (United States)

    Smeaton, Alan F.

    2004-01-01

    Presents a literature review that covers the following topics related to indexing, browsing, and searching of digital video: video coding and standards; conventional approaches to accessing digital video; automatically structuring and indexing digital video; searching, browsing, and summarization; measurement and evaluation of the effectiveness of…

  9. Temporal Subtraction of Digital Breast Tomosynthesis Images for Improved Mass Detection

    Science.gov (United States)

    2007-10-01

    number of low-dose cone-beam projection images", Medical Physics 30 (3), 365 (2003). 9 E.A. Sickles, W.N. Weber, H.B. Galvin, S.H. Ominsky, and R.A...temporal pairs of mammograms for interval change analysis--local affine transformation for improved localization", Medical Physics 28 (6), 1070 (2001...aided classification of malignant and benign breast masses", Medical Physics 28 (11), 2309 (2001). 25 K. Marias, C. Behrenbruch, S. Parbhoo, A

  10. Value of digital subtraction angiography for the evaluation of peripheral arteriovenous shunts in patients with haemodialysis

    Energy Technology Data Exchange (ETDEWEB)

    Beil, D.; Bolsinger, G.; Deininger, H.K.

    1987-02-01

    Direct and indirect examination of arteriovenous shunts was performed in 50 patients undergoing haemodialysis. The various methods of puncture of the vessels, the indications and the limitations of DSA are considered. The advantages of direct puncture of the arteriovenous shunt are emphasised. Puncture of the venous branch is almost without risk and allows immediate diagnosis. Only in a very few cases it will be necessary to perform the risky puncture of the arterial branch or the time-consuming central venous injection of a bolus of the contrast medium.

  11. Transvenous digital subtraction angiography (DSA) of the thoracic aorta after surgical correction of aortic coarctation

    Energy Technology Data Exchange (ETDEWEB)

    Arlart, I.P.; Hamann, H.; Stenz, R.

    1985-01-01

    25 patients (normotensive n = 19, hypertensive n = 6) underwent DSA control following corrective surgery of a coarcatation of the thoracic aorta to exclude vascular complications. Simultaneously pressure gradients were determined between upper and lower extremities using the doppler-sonography. DSA was diagnostic in all patients. 2 cases showed a patch-dependent dilatation, in 1 case an anastomotic aneurysm could be demonstrated. In 6 patients with hypoplastic aortic arch and 2 patients with a slight reduction of the diameter in the anastomotic region a pathological pressure-gradient was measured. In these patients the ratio of aortic arch rsp. anastomosis/descending aorta was reduced in diameter (< 0,66) and area (< 44). Hypertension could not be related to pressure gradients or vascular disorders.

  12. The analysis of cerebro-vascular circulation time using digital subtraction angiography (DSA)

    Energy Technology Data Exchange (ETDEWEB)

    Han, D. G.; Kim, D. H.; Lee, H. K.; Kwon, K. H.; Kim, K. J. [Soonchunhyang University College of Medicine, Asan (Korea, Republic of)

    1986-10-15

    We analyzed the cerebral arterio-venous circulation time of 141 cases of cranial DSA in 136 patients, for the assessment of cerebral circulatory dynamics. IV-DSA was 111 cases, IA-DSA 30 cases. The results were as follows: 1. There was no significant difference in arterio-venous circulation time between IA-DSA and IV-DSA, if the disease pattern was not considered (P > 0.1). 2. Prolongation of arterio-venous circulation time was noted in the cases of cerebral (cerebellar) hemorrhage, subarachnoid hemorrhage, intracranial hematoma, brain abscess, acute stage of cerebra-vascular occlusive disease, acute stage of postoperative follow up, and acute stage of cerebral contusion (p > 0.05). 3. Compared the chronic stage of cerebra-vascular occlusive disease, postoperative follow up, and cerebral contusion with acute stage, significant decrement of arterio-venous circulation time was resulted (p > 0.05). 4. DSA was a useful modality for the assessment of circulatory dynamics, including measurement of arterio-venous circulation time.

  13. Quantitative digital subtraction radiography for assessment of bone density changes following periodontal guided tissue regeneration

    National Research Council Canada - National Science Library

    Christgau, M; Wenzel, A; Hiller, K A; Schmalz, G

    1996-01-01

    ...). Twelve patients with 30 intrabony lesions and 16 furcation defects took part. Standardized radiographic and clinical examinations were carried out immediately before and then 5 and 13 months after surgery...

  14. Evaluation of renal donors and recipients using intravenous digital subtraction angiography

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Deuk Lin; Kim, Ki Jeung [Soonchunhyang Medical College, Seoul (Korea, Republic of)

    1986-04-15

    Renal IV DSA was applied to evaluate 15 potential renal donors and 14 examinations of 12 renal allograft recipients. We evaluate the angiographic acute or chronic rejection, alteration of renal size after transplantation, excretion time of the contrast media and pre, post DSA serum creatinine level. DSA is a safe, easily performed, outpatient procedure and useful in evaluation and distinguishing status of surgical anastomosis, intrarenal vasculatures, arterial exception time and rejection phenomenon.

  15. Nested soft-collinear subtractions in NNLO QCD computations

    Energy Technology Data Exchange (ETDEWEB)

    Caola, Fabrizio [CERN, Theoretical Physics Department, Geneva (Switzerland); IPPP, Durham University, Durham (United Kingdom); Melnikov, Kirill; Roentsch, Raoul [Institute for Theoretical Particle Physics, KIT, Karlsruhe (Germany)

    2017-04-15

    We discuss a modification of the next-to-next-to-leading order (NNLO) subtraction scheme based on the residue-improved sector decomposition that reduces the number of double-real emission sectors from five to four. In particular, a sector where energies and angles of unresolved particles vanish in a correlated fashion is redundant and can be discarded. This simple observation allows us to formulate a transparent iterative subtraction procedure for double-real emission contributions, to demonstrate the cancellation of soft and collinear singularities in an explicit and (almost) process-independent way and to write the result of a NNLO calculation in terms of quantities that can be computed in four space-time dimensions. We illustrate this procedure explicitly in the simple case of O(α{sub s}{sup 2}) gluonic corrections to the Drell-Yan process of q anti q annihilation into a lepton pair. We show that this framework leads to fast and numerically stable computation of QCD corrections. (orig.)

  16. Background Subtraction Based on Three-Dimensional Discrete Wavelet Transform.

    Science.gov (United States)

    Han, Guang; Wang, Jinkuan; Cai, Xi

    2016-03-30

    Background subtraction without a separate training phase has become a critical task, because a sufficiently long and clean training sequence is usually unavailable, and people generally thirst for immediate detection results from the first frame of a video. Without a training phase, we propose a background subtraction method based on three-dimensional (3D) discrete wavelet transform (DWT). Static backgrounds with few variations along the time axis are characterized by intensity temporal consistency in the 3D space-time domain and, hence, correspond to low-frequency components in the 3D frequency domain. Enlightened by this, we eliminate low-frequency components that correspond to static backgrounds using the 3D DWT in order to extract moving objects. Owing to the multiscale analysis property of the 3D DWT, the elimination of low-frequency components in sub-bands of the 3D DWT is equivalent to performing a pyramidal 3D filter. This 3D filter brings advantages to our method in reserving the inner parts of detected objects and reducing the ringing around object boundaries. Moreover, we make use of wavelet shrinkage to remove disturbance of intensity temporal consistency and introduce an adaptive threshold based on the entropy of the histogram to obtain optimal detection results. Experimental results show that our method works effectively in situations lacking training opportunities and outperforms several popular techniques.

  17. Quasi-Normal Modes for Subtracted Rotating and Magnetised Geometries

    CERN Document Server

    Cvetic, M; Saleem, Z H

    2014-01-01

    We obtain explicit separable solutions of the wave equation of massless minimally coupled scalar fields in the subtracted geometry of four-dimensional rotating and Melvin (magnetised) four-charge black holes of the STU model, a consistent truncation of maximally supersymmetric supergravity with four types of electromagnetic fields. These backgrounds possess a hidden SL(2,R) x SL(2,R) x SO(3) symmetry and faithfully model the near horizon geometry of these black holes, but locate them in a confining asymptotically conical box. For each subtracted geometry we obtain two branches of quasi-normal modes, given in terms of hypergeometric functions and spherical harmonics. One branch is over-damped and the other under-damped and they exhibit rotational splitting. No black hole bomb is possible because the Killing field which co-rotates with the horizon is everywhere timelike outside the black hole. A five-dimensional lift of these geometries is given locally by the product of a BTZ black hole with a a two-sphere. Th...

  18. Infinite S-expansion with ideal subtraction and some applications

    Science.gov (United States)

    Peñafiel, D. M.; Ravera, L.

    2017-08-01

    According to the literature, the S-expansion procedure involving a finite semigroup is valid no matter what the structure of the original Lie (super)algebra is; however, when something about the structure of the starting (super)algebra is known and when certain particular conditions are met, the S-expansion method (with its features of resonance and reduction) is able not only to lead to several kinds of expanded (super)algebras but also to reproduce the effects of the standard as well as the generalized Inönü-Wigner contraction. In the present paper, we propose a new prescription for S-expansion, involving an infinite abelian semigroup S(∞ ) and the subtraction of an infinite ideal subalgebra. We show that the subtraction of the infinite ideal subalgebra corresponds to a reduction. Our approach is a generalization of the finite S-expansion procedure presented in the literature, and it offers an alternative view of the generalized Inönü-Wigner contraction. We then show how to write the invariant tensors of the target (super)algebras in terms of those of the starting ones in the infinite S-expansion context presented in this work. We also give some interesting examples of application on algebras and superalgebras.

  19. Digital Preservation.

    Science.gov (United States)

    Yakel, Elizabeth

    2001-01-01

    Reviews research on digital preservation issues, including born-digital and digitally recreated documents. Discusses electronic records research; metadata and other standards; electronic mail; Web-based documents; moving images media; selection of materials for digitization, including primary sources; administrative issues; media stability…

  20. Once and twice subtracted dispersion relations in the analysis of pi pi amplitudes

    CERN Document Server

    Kaminski, R; Peláez, J R; Ynduráin, F J

    2009-01-01

    Once and twice subtracted crossing symmetric dispersion relations applied to $\\pi\\pi \\to \\pi\\pi$ scattering data are analyzed and compared. Both sets of dispersion relations can be used to test the $\\pi\\pi$ amplitudes in low partial waves up to about 1 GeV. We show how once subtracted dispersion relations can provide stronger constraints for $\\pi\\pi$ amplitudes than twice subtracted ones in the 400 to 1100 MeV range, given the same experimental input.

  1. The association between symbolic and nonsymbolic numerical magnitude processing and mental versus algorithmic subtraction in adults.

    Science.gov (United States)

    Linsen, Sarah; Torbeyns, Joke; Verschaffel, Lieven; Reynvoet, Bert; De Smedt, Bert

    2016-03-01

    There are two well-known computation methods for solving multi-digit subtraction items, namely mental and algorithmic computation. It has been contended that mental and algorithmic computation differentially rely on numerical magnitude processing, an assumption that has already been examined in children, but not yet in adults. Therefore, in this study, we examined how numerical magnitude processing was associated with mental and algorithmic computation, and whether this association with numerical magnitude processing was different for mental versus algorithmic computation. We also investigated whether the association between numerical magnitude processing and mental and algorithmic computation differed for measures of symbolic versus nonsymbolic numerical magnitude processing. Results showed that symbolic, and not nonsymbolic, numerical magnitude processing was associated with mental computation, but not with algorithmic computation. Additional analyses showed, however, that the size of this association with symbolic numerical magnitude processing was not significantly different for mental and algorithmic computation. We also tried to further clarify the association between numerical magnitude processing and complex calculation by also including relevant arithmetical subskills, i.e. arithmetic facts, needed for complex calculation that are also known to be dependent on numerical magnitude processing. Results showed that the associations between symbolic numerical magnitude processing and mental and algorithmic computation were fully explained by individual differences in elementary arithmetic fact knowledge.

  2. It Works Both Ways: Transfer Difficulties between Manipulatives and Written Subtraction Solutions

    Directory of Open Access Journals (Sweden)

    David H. Uttal

    2013-01-01

    Full Text Available Three experiments compared performance and transfer among children aged 83–94 months after written or manipulatives instruction on two-digit subtraction. In Experiment 1a, children learned with manipulatives or with traditional written numerals. All children then completed a written posttest. Experiment 1b investigated whether salient or perceptually attractive manipulatives affected transfer. Experiment 2 investigated whether instruction with writing would transfer to a manipulatives-based posttest. Children demonstrated performance gains when the posttest format was identical to the instructed format but failed to demonstrate transfer from the instructed format to an incongruent posttest. The results indicate that the problem in transferring from manipulatives instruction to written assessments stems from a general difficulty in using knowledge gained in one format (e.g., manipulatives in another format (e.g., writing. Taken together, the results have important implications for research and teaching in early mathematics. Teachers should consider making specific links and alignments between written and manipulatives-based representations of the same problems.

  3. A posterior registration and subtraction of periapical radiographs for the evaluation of external apical root resorption after orthodontic treatment

    Energy Technology Data Exchange (ETDEWEB)

    Kreich, Eliane Maria; Chibinski, Ana Claudia; Coelho, Ulisses; Wambier, Leticia Stadler; Zedebski, Rosaio De Arruda Moura [School of Dentistry, Ponta Grossa State University, Ponta Grossa, Parana (Brazil); De Moraes, Mari Eli Leonelli; De Moraes, Luiz Cesar [Dept. of Dental Radiology, School of Dentistry, State University of Sao Paulo, Sao Jose dos Campos, Sao Paulo (Brazil)

    2016-03-15

    This study employed a posteriori registration and subtraction of radiographic images to quantify the apical root resorption in maxillary permanent central incisors after orthodontic treatment, and assessed whether the external apical root resorption (EARR) was related to a range of parameters involved in the treatment. A sample of 79 patients (mean age, 13.5±2.2 years) with no history of trauma or endodontic treatment of the maxillary permanent central incisors was selected. Periapical radiographs taken before and after orthodontic treatment were digitized and imported to the Regeemy software. Based on an analysis of the posttreatment radiographs, the length of the incisors was measured using Image J software. The mean EARR was described in pixels and relative root resorption (%). The patient's age and gender, tooth extraction, use of elastics, and treatment duration were evaluated to identify possible correlations with EARR. The mean EARR observed was 15.44±12.1 pixels (5.1% resorption). No differences in the mean EARR were observed according to patient characteristics (gender, age) or treatment parameters (use of elastics, treatment duration). The only parameter that influenced the mean EARR of a patient was the need for tooth extraction. A posteriori registration and subtraction of periapical radiographs was a suitable method to quantify EARR after orthodontic treatment, and the need for tooth extraction increased the extent of root resorption after orthodontic treatment.

  4. A posteriori registration and subtraction of periapical radiographs for the evaluation of external apical root resorption after orthodontic treatment

    Science.gov (United States)

    Chibinski, Ana Cláudia; Coelho, Ulisses; Wambier, Letícia Stadler; Zedebski, Rosário de Arruda Moura; de Moraes, Mari Eli Leonelli; de Moraes, Luiz Cesar

    2016-01-01

    Purpose This study employed a posteriori registration and subtraction of radiographic images to quantify the apical root resorption in maxillary permanent central incisors after orthodontic treatment, and assessed whether the external apical root resorption (EARR) was related to a range of parameters involved in the treatment. Materials and Methods A sample of 79 patients (mean age, 13.5±2.2 years) with no history of trauma or endodontic treatment of the maxillary permanent central incisors was selected. Periapical radiographs taken before and after orthodontic treatment were digitized and imported to the Regeemy software. Based on an analysis of the posttreatment radiographs, the length of the incisors was measured using Image J software. The mean EARR was described in pixels and relative root resorption (%). The patient's age and gender, tooth extraction, use of elastics, and treatment duration were evaluated to identify possible correlations with EARR. Results The mean EARR observed was 15.44±12.1 pixels (5.1% resorption). No differences in the mean EARR were observed according to patient characteristics (gender, age) or treatment parameters (use of elastics, treatment duration). The only parameter that influenced the mean EARR of a patient was the need for tooth extraction. Conclusion A posteriori registration and subtraction of periapical radiographs was a suitable method to quantify EARR after orthodontic treatment, and the need for tooth extraction increased the extent of root resorption after orthodontic treatment. PMID:27051635

  5. Cadmium Subtraction Method for the Active Albedo Neutron Interrogation of Uranium

    Energy Technology Data Exchange (ETDEWEB)

    Worrall, Louise G. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Croft, Stephen [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-02-01

    This report describes work performed under the Next Generation Safeguards Initiative (NGSI) Cadmium Subtraction Project. The project objective was to explore the difference between the traditional cadmium (Cd) ratio signature and a proposed alternative Cd subtraction (or Cd difference) approach. The thinking behind the project was that a Cd subtraction method would provide a more direct measure of multiplication than the existing Cd ratio method. At the same time, it would be relatively insensitive to changes in neutron detection efficiency when properly calibrated. This is the first published experimental comparison and evaluation of the Cd ratio and Cd subtraction methods.

  6. On-sky tests of sky-subtraction methods for fiber-fed spectrographs

    CERN Document Server

    Rodrigues, Myriam; Hammer, Francois; Royer, Frederic; Evans, C J; Puech, Mathieu; Flores, Hector; Guinouard, Isabelle; Causi, Gianluca Li; Disseau, Karen; Yang, Yanbin

    2016-01-01

    We present preliminary results on on-sky test of sky subtraction methods for fiber-fed spectrograph. Using dedicated observation with FLAMES/VLT in I-band, we have tested the accuracy of the sky subtraction for 4 sky subtraction methods: mean sky, closest sky, dual stare and cross-beam switching. The cross beam-switching and dual stare method reach accuracy and precision of the sky subtraction under 1%. In contrast to the commonly held view in the literature, this result points out that fiber-fed spectrographs are adapted for the observations of faint targets.

  7. Graphics processing unit aided highly stable real-time spectral-domain optical coherence tomography at 1375 nm based on dual-coupled-line subtraction

    Science.gov (United States)

    Kim, Ji-hyun; Han, Jae-Ho; Jeong, Jichai

    2013-04-01

    We have proposed and demonstrated a highly stable spectral-domain optical coherence tomography (SD-OCT) system based on dual-coupled-line subtraction. The proposed system achieved an ultrahigh axial resolution of 5 μm by combining four kinds of spectrally shifted superluminescent diodes at 1375 nm. Using the dual-coupled-line subtraction method, we made the system insensitive to fluctuations of the optical intensity that can possibly arise in various clinical and experimental conditions. The imaging stability was verified by perturbing the intensity by bending an optical fiber, our system being the only one to reduce the noise among the conventional systems. Also, the proposed method required less computational complexity than conventional mean- and median-line subtraction. The real-time SD-OCT scheme was implemented by graphics processing unit aided signal processing. This is the first reported reduction method for A-line-wise fixed-pattern noise in a single-shot image without estimating the DC component.

  8. Varieties of conventional implicature

    Directory of Open Access Journals (Sweden)

    Eric Scott McCready

    2010-07-01

    Full Text Available This paper provides a system capable of analyzing the combinatorics of a wide range of conventionally implicated and expressive constructions in natural language via an extension of Potts's (2005 L_CI logic for supplementary conventional implicatures. In particular, the system is capable of analyzing objects of mixed conventionally implicated/expressive and at-issue type, and objects with conventionally implicated or expressive meanings which provide the main content of their utterances. The logic is applied to a range of constructions and lexical items in several languages. doi:10.3765/sp.3.8 BibTeX info

  9. Suppression Subtractive Hybridization (SSH) and its modifications in microbiological research.

    Science.gov (United States)

    Huang, Xiaowei; Li, Yunxia; Niu, Qiuhong; Zhang, Keqin

    2007-09-01

    Suppression subtractive hybridization (SSH) is an effective approach to identify the genes that vary in expression levels during different biological processes. It is often used in higher eukaryotes to study the molecular regulation in complex pathogenic progress, such as tumorigenesis and other chronic multigene-associated diseases. Because microbes have relatively smaller genomes compared with eukaryotes, aside from the analysis at the mRNA level, SSH as well as its modifications have been further employed to isolate specific chromosomal locus, study genomic diversity related with exceptional bacterial secondary metabolisms or genes with special microbial function. This review introduces the SSH and its associated methods and focus on their applications to detect specific functional genes or DNA markers in microorganisms.

  10. Analysis of radiohippuran renogram by subtraction of extrarenal radioactivity

    Energy Technology Data Exchange (ETDEWEB)

    Razzak, M.A.; Botti, R.E.; Macintyre, W.J.

    1976-05-01

    A method is presented for the simple, non-computerized analysis of the radiohippuran renogram by subtraction of the extrarenal radioactivity as monitored simultaneously by a detector centered over the manubrium sterni. This method requires the application of a calibration factor, relating the level of radioactivity recorded by the sternal detector to that over each kidney area at the end point of the phase of initial rise on each side separately. The results in 15 normal individuals showed a narrow range of values, indicating a high degree of resolution. Verification of the basis of this method of analysis was obtained by accounting for all of the counting rate as extrarenal sources in the tracings of nephrectomized subjects. A further advantage is that the tracing recorded by the sternal detector may be used to calculate renal blood flow.

  11. Background Subtraction with DirichletProcess Mixture Models.

    Science.gov (United States)

    Haines, Tom S F; Tao Xiang

    2014-04-01

    Video analysis often begins with background subtraction. This problem is often approached in two steps-a background model followed by a regularisation scheme. A model of the background allows it to be distinguished on a per-pixel basis from the foreground, whilst the regularisation combines information from adjacent pixels. We present a new method based on Dirichlet process Gaussian mixture models, which are used to estimate per-pixel background distributions. It is followed by probabilistic regularisation. Using a non-parametric Bayesian method allows per-pixel mode counts to be automatically inferred, avoiding over-/under- fitting. We also develop novel model learning algorithms for continuous update of the model in a principled fashion as the scene changes. These key advantages enable us to outperform the state-of-the-art alternatives on four benchmarks.

  12. Hierarchical CodeBook for background subtraction in MRF

    Science.gov (United States)

    Shao, Quan; Tang, Zhixing; Han, Songchen

    2013-11-01

    Foreground detection is the key low-level fundamental work in intelligent video surveillance. This paper proposed a hierarchical background subtraction algorithm consisted of block-based stage and pixel-based stage for it. In block-based stage, obvious backgrounds got detected via block-based CodeBook, leaving spatial relations among suspicious foreground pixels undestroyed. Pixel-based stage further eliminated the left background pixels with the introduction of spatial and temporal relations in a MRF-MAP framework. Then comparative experiments were conducted to evaluate the performance of the scheme in three dimensions - detection accuracy, update speed and memory consumption. Proposed approach possesses the highest detection precision and consumes the second least memories. And the update speed is of real-time level.

  13. Subtraction of "accidentals" and the validity of Bell tests

    CERN Document Server

    Thompson, C H

    1999-01-01

    In some key Bell experiments, including two of the well-known ones by Alain Aspect, 1981-2, it is only after the subtraction of ``accidentals'' from the coincidence counts that we get violations of Bell tests. The data adjustment, producing increases of up to 60% in the test statistics, has never been adequately justified. Few published experiments give sufficient information for the reader to make a fair assessment. There is a straightforward and well known realist model that fits the unadjusted data very well. In this paper, the logic of this realist model and the reasoning used by experimenters in justification of the data adjustment are discussed. It is concluded that the evidence from all Bell experiments is in urgent need of re-assessment, in the light of all the known ``loopholes''. Invalid Bell tests have frequently been used, neglecting an improved one derived by Clauser and Horne in 1974. ``Local causal'' explanations for the observations have been wrongfully neglected.

  14. PSF subtraction to search for distant Jupiters with SPITZER

    Science.gov (United States)

    Rameau, Julien; Artigau, Etienne; Baron, Frédérique; Lafrenière, David; Doyon, Rene; Malo, Lison; Naud, Marie-Eve; Delorme, Philippe; Janson, Markus; Albert, Loic; Gagné, Jonathan; Beichman, Charles

    2015-12-01

    In the course of the search for extrasolar planets, a focus has been made towards rocky planets very close (within few AUs) to their parent stars. However, planetary systems might host gas giants as well, possibly at larger separation from the central star. Direct imaging is the only technique able to probe the outer part of planetary systems. With the advent of the new generation of planet finders like GPI and SPHERE, extrasolar systems are now studied at the solar system scale. Nevertheless, very extended planetary systems do exist and have been found (Gu Ps, AB Pic b, etc.). They are easier to detect and characterize. They are also excellent proxy for close-in gas giants that are detected from the ground. These planets have no equivalent in our solar system and their origin remain a matter of speculation. In this sense, studying planetary systems from its innermost to its outermost part is therefore mandatory to have a clear understanding of its architecture, hence hints of its formation and evolution. We are carrying out a space-based survey using SPITZER to search for distant companions around a well-characterized sample of 120 young and nearby stars. We designed an observing strategy that allows building a very homogeneous PSF library. With this library, we perform a PSF subtraction to search for planets from 10’’ down to 1’’. In this poster, I will present the library, the different algorithms used to subtract the PSF, and the promising detection sensitivity that we are able to reach with this survey. This project to search for the most extreme planetary systems is unique in the exoplanet community. It is also the only realistic mean of directly imaging and subsequently obtaining spectroscopy of young Saturn or Jupiter mass planets in the JWST-era.

  15. Digital Culture and Digital Library

    Directory of Open Access Journals (Sweden)

    Yalçın Yalçınkaya

    2016-12-01

    Full Text Available In this study; digital culture and digital library which have a vital connection with each other are examined together. The content of the research consists of the interaction of culture, information, digital culture, intellectual technologies, and digital library concepts. The study is an entry work to integrity of digital culture and digital library theories and aims to expand the symmetry. The purpose of the study is to emphasize the relation between the digital culture and digital library theories acting intersection of the subjects that are examined. Also the perspective of the study is based on examining the literature and analytical evaluation in both studies (digital culture and digital library. Within this context, the methodology of the study is essentially descriptive and has an attribute for the transmission and synthesis of distributed findings produced in the field of the research. According to the findings of the study results, digital culture is an inclusive term that describes the effects of intellectual technologies in the field of information and communication. Information becomes energy and the spectrum of the information is expanding in the vertical rise through the digital culture. In this context, the digital library appears as a new living space of a new environment. In essence, the digital library is information-oriented; has intellectual technology support and digital platform; is in a digital format; combines information resources and tools in relationship/communication/cooperation by connectedness, and also it is the dynamic face of the digital culture in time and space independence. Resolved with the study is that the digital libraries are active and effective in the formation of global knowing and/or mass wisdom in the process of digital culture.

  16. A subtraction scheme for computing QCD jet cross sections at NNLO. Integrating the iterated singly-unresolved subtraction terms

    Energy Technology Data Exchange (ETDEWEB)

    Bolzoni, Paolo [Hamburg Univ. (Germany). II. Inst. fuer Theoretische Physik; Somogyi, Gabor [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Trocsanyi, Zoltan [Debrecen Univ. (Hungary); Hungarian Academy of Sciences, Debrecen (Hungary). Inst. of Nuclear Research

    2010-11-15

    We perform the integration of all iterated singly-unresolved subtraction terms over the two-particle factorized phase space. We also sum over the unresolved parton flavours. The final result can be written as a convolution (in colour space) of the Born cross section and an insertion operator. We spell out the insertion operator in terms of 24 basic integrals that are defined explicitly. We compute the coefficients of the Laurent-expansion of these integrals in two different ways, with the method of Mellin-Barnes representations and sector decomposition. Finally, we present the Laurentexpansion of the full insertion operator for the specific examples of electron-positron annihilation into two and three jets. (orig.)

  17. Data acquisition and analysis for the energy-subtraction Compton scatter camera for medical imaging

    Science.gov (United States)

    Khamzin, Murat Kamilevich

    In response to the shortcomings of the Anger camera currently being used in conventional SPECT, particularly the trade-off between sensitivity and spatial resolution, a novel energy-subtraction Compton scatter camera, or the ESCSC, has been proposed. A successful clinical implementation of the ESCSC could revolutionize the field of SPECT. Features of this camera include utilization of silicon and CdZnTe detectors in primary and secondary detector systems, list-mode time stamping data acquisition, modular architecture, and post-acquisition data analysis. Previous ESCSC studies were based on Monte Carlo modeling. The objective of this work is to test the theoretical framework developed in previous studies by developing the data acquisition and analysis techniques necessary to implement the ESCSC. The camera model working in list-mode with time stamping was successfully built and tested thus confirming potential of the ESCSC that was predicted in previous simulation studies. The obtained data were processed during the post-acquisition data analysis based on preferred event selection criteria. Along with the construction of a camera model and proving the approach, the post-acquisition data analysis was further extended to include preferred event weighting based on the likelihood of a preferred event to be a true preferred event. While formulated to show ESCSC capabilities, the results of this study are important for any Compton scatter camera implementation as well as for coincidence data acquisition systems in general.

  18. Averaged subtracted polarization imaging for endoscopic diagnostics of surface microstructures on translucent mucosae

    Science.gov (United States)

    Kanamori, Katsuhiro

    2016-07-01

    An endoscopic image processing technique for enhancing the appearance of microstructures on translucent mucosae is described. This technique employs two pairs of co- and cross-polarization images under two different linearly polarized lights, from which the averaged subtracted polarization image (AVSPI) is calculated. Experiments were then conducted using an acrylic phantom and excised porcine stomach tissue using a manual experimental setup with ring-type lighting, two rotating polarizers, and a color camera; better results were achieved with the proposed method than with conventional color intensity image processing. An objective evaluation method that uses texture analysis was developed and used to evaluate the enhanced microstructure images. This paper introduces two types of online, rigid-type, polarimetric endoscopic implementations using a polarized ring-shaped LED and a polarimetric camera. The first type uses a beam-splitter-type color polarimetric camera, and the second uses a single-chip monochrome polarimetric camera. Microstructures on the mucosa surface were enhanced robustly with these online endoscopes regardless of the difference in the extinction ratio of each device. These results show that polarimetric endoscopy using AVSPI is both effective and practical for hardware implementation.

  19. Digital photography

    National Research Council Canada - National Science Library

    Windsor, J S; Rodway, G W; Middleton, P M; McCarthy, S

    2006-01-01

    The emergence of a new generation of "point-and-shoot" digital cameras offers doctors a compact, portable and user-friendly solution to the recording of highly detailed digital photographs and video images...

  20. Putting Essential Understanding of Addition and Subtraction into Practice: Pre-K-2

    Science.gov (United States)

    Caldwell, Janet H.; Kobett, Beth; Karp, Karen

    2014-01-01

    Do your students have the incorrect idea that addition "makes numbers bigger" and subtraction "makes numbers smaller"? Do they believe that subtraction is always "taking away"? What tasks can you offer--what questions can you ask--to determine what your students know or don't know--and move them forward in their…

  1. Putting Essential Understanding of Addition and Subtraction into Practice: Pre-K-2

    Science.gov (United States)

    Caldwell, Janet H.; Kobett, Beth; Karp, Karen

    2014-01-01

    Do your students have the incorrect idea that addition "makes numbers bigger" and subtraction "makes numbers smaller"? Do they believe that subtraction is always "taking away"? What tasks can you offer--what questions can you ask--to determine what your students know or don't know--and move them forward in their…

  2. Curricular Approaches to Connecting Subtraction to Addition and Fostering Fluency with Basic Differences in Grade 1

    Science.gov (United States)

    Baroody, Arthur J.

    2016-01-01

    Six widely used US Grade 1 curricula do not adequately address the following three developmental prerequisites identified by a proposed learning trajectory for the meaningful learning of the subtraction-as-addition strategy (e.g., for 13-8 think "what + 8 = 13?"): (a) reverse operations (adding 8 is undone by subtracting 8); (b) common…

  3. Digital Tectonics

    DEFF Research Database (Denmark)

    Christiansen, Karl; Borup, Ruben; Søndergaard, Asbjørn;

    2014-01-01

    Digital Tectonics treats the architectonical possibilities in digital generation of form and production. The publication is the first volume of a series, in which aspects of the strategic focus areas of the Aarhus School of Architecture will be disseminated.......Digital Tectonics treats the architectonical possibilities in digital generation of form and production. The publication is the first volume of a series, in which aspects of the strategic focus areas of the Aarhus School of Architecture will be disseminated....

  4. Digital squares

    DEFF Research Database (Denmark)

    Forchhammer, Søren; Kim, Chul E

    1988-01-01

    Digital squares are defined and their geometric properties characterized. A linear time algorithm is presented that considers a convex digital region and determines whether or not it is a digital square. The algorithm also determines the range of the values of the parameter set of its preimages....... The analysis involves transforming the boundary of a digital region into parameter space of slope and y-intercept...

  5. 99mTc-RBC连续减影显像诊断胃肠出血的临床价值%Clinical value of sequential subtraction scintigraphy with 99m  Tc-RBC for gastrointestinal bleeding

    Institute of Scientific and Technical Information of China (English)

    吴翼伟; 濑户光

    2001-01-01

    目的 99m Tc-RBC连续减影显像为早期诊断胃肠出血提供了新的手段。本文评价其临床应用价值。 方法用数字Υ相机对90例疑诊胃肠出血患者行99m Tc体内标记红细胞胃肠出血显像。每帧5分钟,连续采集60分钟,得到12帧常规非减影图像(CNS)。12帧动态图像用计算机以t+5分钟为时间轴作连续减影处理,得到11帧减影图像(SSS)。若早期显像结果为阴性或怀疑有再出血时行3、6或24小时延迟显像。 结果 90例疑诊胃肠出血患者中,62例确诊为活动性胃肠出血。图像以30分钟、60分钟以及24小时内三个时间段进行分析。SSS的灵敏度分别为87%(30分钟)和92.8%(60分钟),明显高于CNS的56.4%(30分钟)和63.9%(60分钟)。24小时延迟显像CNS的灵敏度增至85.4%。两种方法的特异性之间无明显差异。62例确诊病人中42例经手术明确出血部位。SSS的定位诊断符合率为92.8,明显高于CNS的73.8%。 结论 99mTc-RBC连续减影显像是一种早期诊断胃肠出血的有效方法,较之常规非减影显像能够更早期、更准确地对微量胃肠出血作出定性定位诊断。%Objective To evaluate the clinical value of sequential subtraction scintigraphy (SSS) with 99m Tc red blood cell (RBC) for the early detection of gastrointestinal (GI) bleeding. Methods Ninety patients referred with clinical evidence of GI bleeding underwent 99m Tc-RBC scintigraphy with digital gamma camera after labeling of 99m  Tc-RBC in vivo. Sequential 12 conventional non-subtraction (CNS) images of abdomen were taken at 5?min intervals for 60?min. Then 5-min images were subsequently subtracted from each other using a computer and 11 subtracted images were obtained. Delayed images up to 24 hr were obtained when early results were negative and/or recurrent bleeding was suspected. Results 62 of 90 patients with suspected GI bleeding were conformed to have active

  6. 基于听觉掩蔽效应的多频带谱减语音增强方法%Multi-band spectral subtraction method for speech enhancement based on masking property of human auditory system

    Institute of Scientific and Technical Information of China (English)

    曹亮; 张天骐; 高洪兴; 易琛

    2013-01-01

    In order to reduce the music noise introduced by conventional spectral subtraction method for speech enhancement, a speech enhancement algorithm is put forward based on the combination of multi-band spectral subtraction and the masking properties of human auditory system. Firstly, the weighted recursive averaging method is used to estimate the noise power spectrum, exert subtraction of multi-band on the noise-corrupted speech signal; then, auditory masking threshold is computed using the estimated speech signal, adjust the subtraction factor according to the threshold masking; finally, we obtain the spectrum of enhanced speech through computing the gain faction according to the subtraction factor. The simulation shows that, at low SNR, compared with conventional spectral subtraction, background noise and residual music noise are effectively suppressed, and the clarity and intelligibility of speech signal are dramatically improved.%为了减小传统谱减法引入的音乐噪声,提出了一种将多频带谱减和听觉掩蔽效应相结合的语音增强算法.用加权递归平滑的方法估计噪声的功率谱,对带噪的语音信号进行多频带谱减,计算听觉掩蔽阈值,再根据掩蔽阈值动态地调节谱减因子,通过增益函数得到增强后语音信号的频谱.仿真实验结果表明,与传统的谱减法相比,该算法在信噪比较低情况下,背景噪声和残余噪声得到了有效的抑制,语音信号的清晰度和可懂度也有了明显提升.

  7. Digital Citizenship

    Science.gov (United States)

    Isman, Aytekin; Canan Gungoren, Ozlem

    2014-01-01

    Era in which we live is known and referred as digital age.In this age technology is rapidly changed and developed. In light of these technological advances in 21st century, schools have the responsibility of training "digital citizen" as well as a good citizen. Digital citizens must have extensive skills, knowledge, Internet and …

  8. Speech Enhancement with Geometric Advent of Spectral Subtraction using Connected Time-Frequency Regions Noise Estimation

    Directory of Open Access Journals (Sweden)

    Nasir Saleem

    2013-06-01

    Full Text Available Speech enhancement with Geometric Advent of Spectral subtraction using connected time-frequency regions noise estimation aims to de-noise or reduce background noise from the noisy speech for better quality, pleasantness and improved intelligibility. Numerous enhancement methods are proposed including spectral subtraction, subspace, statistical with different noise estimations. The traditional spectral subtraction techniques are reasonably simple to implement and suffer from musical noise. This study addresses the new approach for speech enhancement which has minimized the insufficiencies in traditional spectral subtraction algorithms using MCRA. This approach with noise estimation has been evolved with PESQ, the ITU-T standard; Frequency weighted segmental SNR and weighted spectral slope. The analysis shows that Geometric approach with time-frequency connected regions has improved results than old-fashioned spectral subtraction algorithms. The normal hearing tests has suggested that new approach has lower audible musical noise.

  9. Improvement of two-way continuous-variable quantum key distribution with virtual photon subtraction

    Science.gov (United States)

    Zhao, Yijia; Zhang, Yichen; Li, Zhengyu; Yu, Song; Guo, Hong

    2017-08-01

    We propose a method to improve the performance of two-way continuous-variable quantum key distribution protocol by virtual photon subtraction. The virtual photon subtraction implemented via non-Gaussian post-selection not only enhances the entanglement of two-mode squeezed vacuum state but also has advantages in simplifying physical operation and promoting efficiency. In two-way protocol, virtual photon subtraction could be applied on two sources independently. Numerical simulations show that the optimal performance of renovated two-way protocol is obtained with photon subtraction only used by Alice. The transmission distance and tolerable excess noise are improved by using the virtual photon subtraction with appropriate parameters. Moreover, the tolerable excess noise maintains a high value with the increase in distance so that the robustness of two-way continuous-variable quantum key distribution system is significantly improved, especially at long transmission distance.

  10. "digital Heritage" Theory and Innovative Practice

    Science.gov (United States)

    He, Y.; Ma, Y. H.; Zhang, X. R.

    2017-08-01

    "Digital heritage", as defined in this paper, is the integration of cultural heritage with digitization technology ("cultural heritage + digitization"), and of digital knowledge with research. It includes not only the three conventional aspects of cultural heritage digitization—digital collection and documentation, digital research and information management, digital presentation and interpretation—but also the creation and innovative use/application of the digital content (cultural heritage intellectual property/IP, experiential education, cultural tourism, film and media). Through analysis of two case studies, the Palazzo Valentini in Rome, Italy, and the Old Summer Palace (Yuanmingyuan) in Beijing, China, the paper assesses the concept of "digital heritage" and proposes a conceptual framework to capture recent developments and future prospects with regard to the industry.

  11. The Geometry of Conventionality

    CERN Document Server

    Weatherall, James Owen

    2013-01-01

    Hans Reichenbach famously argued that the geometry of spacetime is conventional in relativity theory, in the sense that one can freely choose the spacetime metric so long as one is willing to postulate a "universal force field". Here we make precise a sense in which the field Reichenbach defines fails to be a "force". We then argue that there is an interesting and perhaps tenable sense in which geometry is conventional in classical spacetimes. We conclude with a no-go result showing that the variety of conventionalism available in classical spacetimes does not extend to relativistic spacetimes.

  12. Magnetic digital microfluidics - a review.

    Science.gov (United States)

    Zhang, Yi; Nguyen, Nam-Trung

    2017-03-14

    A digital microfluidic platform manipulates droplets on an open surface. Magnetic digital microfluidics utilizes magnetic forces for actuation and offers unique advantages compared to other digital microfluidic platforms. First, the magnetic particles used in magnetic digital microfluidics have multiple functions. In addition to serving as actuators, they also provide a functional solid substrate for molecule binding, which enables a wide range of applications in molecular diagnostics and immunodiagnostics. Second, magnetic digital microfluidics can be manually operated in a "power-free" manner, which allows for operation in low-resource environments for point-of-care diagnostics where even batteries are considered a luxury item. This review covers research areas related to magnetic digital microfluidics. This paper first summarizes the current development of magnetic digital microfluidics. Various methods of droplet manipulation using magnetic forces are discussed, ranging from conventional magnetic particle-based actuation to the recent development of ferrofluids and magnetic liquid marbles. This paper also discusses several new approaches that use magnetically controlled flexible substrates for droplet manipulation. In addition, we emphasize applications of magnetic digital microfluidics in biosensing and medical diagnostics, and identify the current limitations of magnetic digital microfluidics. We provide a perspective on possible solutions to close these gaps. Finally, the paper discusses the future improvement of magnetic digital microfluidics to explore potential new research directions.

  13. Conventional Spinal Anaesthesia

    African Journals Online (AJOL)

    patients scheduled for clcctive unilateral lower limb surgery. ... the conventional group were turned supine immediately after injection. Blood pressure, heart rate, respiratory rate and oxygen .... Characteristic Type of spinal anaesthcsia P-value.

  14. Digital preservation

    CERN Document Server

    Deegan, Marilyn

    2013-01-01

    Digital preservation is an issue of huge importance to the library and information profession right now. With the widescale adoption of the internet and the rise of the world wide web, the world has been overwhelmed by digital information. Digital data is being produced on a massive scale by individuals and institutions: some of it is born, lives and dies only in digital form, and it is the potential death of this data, with its impact on the preservation of culture, that is the concern of this book. So how can information professionals try to remedy this? Digital preservation is a complex iss

  15. Digital signal coding

    Energy Technology Data Exchange (ETDEWEB)

    Gaunt, R.

    1997-05-01

    It seems that digital video has gone by as many names as Jim Blinn has Siggraph ribbons. Some of its various formats and names are: DV, Dl, 4:2:2, CCIR 601-1, ITU-Rec. 601-4,, SMPTE RP125M, and SMPTE 259M. CCIR and CCITT were both absorbed into their parent organization, the International Telecommunications Union (ITU), so technically speaking, CCIR 601 has been renamed to ITU-Rec. 601-4 (``Rec.`` stands for recommendation). But convention is often hard to change, so for some time you will see and hear Dl and CCIR 601 used for serial digital component video. Below are brief descriptions of the various names and formats for digital video.

  16. Digital Natives or Digital Tribes?

    Science.gov (United States)

    Watson, Ian Robert

    2013-01-01

    This research builds upon the discourse surrounding digital natives. A literature review into the digital native phenomena was undertaken and found that researchers are beginning to identify the digital native as not one cohesive group but of individuals influenced by other factors. Primary research by means of questionnaire survey of technologies…

  17. Helmets: conventional to cueing

    Science.gov (United States)

    Sedillo, Michael R.; Dixon, Sharon A.

    2003-09-01

    Aviation helmets have always served as an interface between technology and flyers. The functional evolution of helmets continued with the advent of radio when helmets were modified to accept communication components and later, oxygen masks. As development matured, interest in safety increased as evident in more robust designs. Designing helmets became a balance between adding new capabilities and reducing the helmet's weight. As the research community better defined acceptable limits of weight-tolerances with tools such as the "Knox Box" criteria, system developers added and subtracted technologies while remaining within these limits. With most helmet-mounted technologies being independent of each other, the level of precision in mounting these technologies was not as significant a concern as it is today. The attachment of new components was acceptable as long as the components served their purpose. However this independent concept has become obsolete with the dawn of modern helmet mounted displays. These complex systems are interrelated and demand precision in their attachment to the helmet. The helmets' role now extends beyond serving as a means to mount the technologies to the head, but is now instrumental in critical visual alignment of complex night vision and missile cueing technologies. These new technologies demand a level of helmet fit and component alignment previously not seen in past helmet designs. This paper presents some of the design, integration and logistical issues gleaned during the development of the Joint Helmet Mounted Cueing System (JHMCS) to include the application of head-track technologies in forensic investigations.

  18. Dual energy subtraction method for breast calcification imaging

    Science.gov (United States)

    Koukou, Vaia; Martini, Niki; Fountos, George; Michail, Christos; Sotiropoulou, Panagiota; Bakas, Athanasios; Kalyvas, Nektarios; Kandarakis, Ioannis; Speller, Robert; Nikiforidis, George

    2017-03-01

    The aim of this work was to present an experimental dual energy (DE) method for the visualization of microcalcifications (μCs). A modified radiographic X-ray tube combined with a high resolution complementary metal-oxide-semiconductor (CMOS) active pixel sensor (APS) X-ray detector was used. A 40/70 kV spectral combination was filtered with 100 μm cadmium (Cd) and 1000 μm copper (Cu) for the low/high-energy combination. Homogenous and inhomogeneous breast phantoms and two calcification phantoms were constructed with various calcification thicknesses, ranging from 16 to 152 μm . Contrast-to-noise ratio (CNR) was calculated from the DE subtracted images for various entrance surface doses. A calcification thickness of 152 μm was visible, with mean glandular doses (MGD) in the acceptable levels (below 3 mGy). Additional post-processing on the DE images of the inhomogeneous breast phantom resulted in a minimum visible calcification thickness of 93 μm (MGD=1.62 mGy). The proposed DE method could potentially improve calcification visibility in DE breast calcification imaging.

  19. Skycorr: A general tool for spectroscopic sky subtraction

    CERN Document Server

    Noll, S; Kimeswenger, S; Barden, M; Jones, A M; Modigliani, A; Szyszka, C; Taylor, J

    2014-01-01

    Airglow emission lines, which dominate the optical-to-near-IR sky radiation, show strong, line-dependent variability on various time scales. Therefore, the subtraction of the sky background in the affected wavelength regime becomes a problem if plain sky spectra have to be taken at a different time as the astronomical data. A solution of this issue is the physically motivated scaling of the airglow lines in the plain sky data to fit the sky lines in the object spectrum. We have developed a corresponding instrument-independent approach based on one-dimensional spectra. Our code skycorr separates sky lines and sky/object continuum by an iterative approach involving a line finder and airglow line data. The sky lines are grouped according to their expected variability. The line groups in the sky data are then scaled to fit the sky in the science data. Required pixel-specific weights for overlapping groups are taken from a comprehensive airglow model. Deviations in the wavelength calibration are corrected by fitti...

  20. Microwave detection of breast tumors: comparison of skin subtraction algorithms

    Science.gov (United States)

    Fear, Elise C.; Stuchly, Maria A.

    2000-07-01

    Early detection of breast cancer is an important part of effective treatment. Microwave detection of breast cancer is of interest due to the contrast in dielectric properties of normal and malignant breast tissues. We are investigating a confocal microwave imaging system that adapts ideas from ground penetrating radar to breast cancer detection. In the proposed system, the patient lies prone with the breast extending through a hole in the examining table and encircled by an array of antennas. The breast is illuminated sequentially by each antenna with an ultrawideband signal, and the returns are recorded at the same antenna. Because the antennas are offset from the breast, the dominant component of the recorded returns is the reflection from the thin layer of breast skin. Two methods of reducing this reflection are compared, namely approximation of the signal with two time shifted, scaled and summed returns from a cylinder of skin, and subtraction of the mean of the set of aligned returns. Both approaches provide effective decrease of the skin signal, allowing for tumor detection.

  1. Subtractive fuzzy classifier based driver distraction levels classification using EEG.

    Science.gov (United States)

    Wali, Mousa Kadhim; Murugappan, Murugappan; Ahmad, Badlishah

    2013-09-01

    [Purpose] In earlier studies of driver distraction, researchers classified distraction into two levels (not distracted, and distracted). This study classified four levels of distraction (neutral, low, medium, high). [Subjects and Methods] Fifty Asian subjects (n=50, 43 males, 7 females), age range 20-35 years, who were free from any disease, participated in this study. Wireless EEG signals were recorded by 14 electrodes during four types of distraction stimuli (Global Position Systems (GPS), music player, short message service (SMS), and mental tasks). We derived the amplitude spectrum of three different frequency bands, theta, alpha, and beta of EEG. Then, based on fusion of discrete wavelet packet transforms and fast fourier transform yield, we extracted two features (power spectral density, spectral centroid frequency) of different wavelets (db4, db8, sym8, and coif5). Mean ± SD was calculated and analysis of variance (ANOVA) was performed. A fuzzy inference system classifier was applied to different wavelets using the two extracted features. [Results] The results indicate that the two features of sym8 posses highly significant discrimination across the four levels of distraction, and the best average accuracy achieved by the subtractive fuzzy classifier was 79.21% using the power spectral density feature extracted using the sym8 wavelet. [Conclusion] These findings suggest that EEG signals can be used to monitor distraction level intensity in order to alert drivers to high levels of distraction.

  2. Data series subtraction with unknown and unmodeled background noise

    CERN Document Server

    Vitale, Stefano; Dolesi, Rita; Ferroni, Valerio; Hueller, Mauro; Vetrugno, Daniele; Weber, William Joseph; Audley, Heather; Danzmann, Karsten; Diepholz, Ingo; Hewitson, Martin; Korsakova, Natalia; Ferraioli, Luigi; Gibert, Ferran; Karnesis, Nikolaos; Nofrarias, Miquel; Inchauspe, Henri; Plagnol, Eric; Jennrich, Oliver; McNamara, Paul W; Armano, Michele; Thorpe, James Ira; Wass, Peter

    2014-01-01

    LISA Pathfinder (LPF), ESA's precursor mission to a gravitational wave observatory, will measure the degree to which two test-masses can be put into free-fall, aiming to demonstrate a residual relative acceleration with a power spectral density (PSD) below 30 fm/s$^2$/Hz$^{1/2}$ around 1 mHz. In LPF data analysis, the measured relative acceleration data series must be fit to other various measured time series data. This fitting is required in different experiments, from system identification of the test mass and satellite dynamics to the subtraction of noise contributions from measured known disturbances. In all cases, the background noise, described by the PSD of the fit residuals, is expected to be coloured, requiring that we perform such fits in the frequency domain. This PSD is unknown {\\it a priori}, and a high accuracy estimate of this residual acceleration noise is an essential output of our analysis. In this paper we present a fitting method based on Bayesian parameter estimation with an unknown frequ...

  3. Generalized Subtraction Schemes for the Difference Formulation in Radiation Transport

    Energy Technology Data Exchange (ETDEWEB)

    Luu, T; Brooks, E; Szoke, A

    2008-07-25

    In the difference formulation for the transport of thermally emitted photons, the photon intensity is defined relative to a reference field, the black body at the local material temperature. This choice of reference field removes the cancellation between thermal emission and absorption that is responsible for noise in the Monte Carlo solution of thick systems, but introduces time and space derivative source terms that can not be determined until the end of the time step. It can also lead to noise induced crashes under certain conditions where the real physical photon intensity differs strongly from a black body at the local material temperature. In this report, we consider a difference formulation relative to the material temperature at the beginning of the time step, and in the situations where the radiation intensity more closely follows a temperature other than the local material temperature, that temperature. The result is a method where iterative solution of the material energy equation is efficient and noise induced crashes are avoided. To support our contention that the resulting generalized subtraction scheme is robust, and therefore suitable for practical use, we perform a stability analysis in the thick limit where instabilities usually occur.

  4. Suppression subtractive hybridization: a method for generating differentially regulated or tissue-specific cDNA probes and libraries.

    OpenAIRE

    1996-01-01

    A new and highly effective method, termed suppression subtractive hybridization (SSH), has been developed for the generation of subtracted cDNA libraries. It is based primarily on a recently described technique called suppression PCR and combines normalization and subtraction in a single procedure. The normalization step equalizes the abundance of cDNAs within the target population and the subtraction step excludes the common sequences between the target and driver populations. In a model sys...

  5. A Wireless FSCV Monitoring IC with Analog Background Subtraction and UWB Telemetry

    Science.gov (United States)

    Dorta-Quiñones, Carlos I.; Wang, Xiao Y.; Dokania, Rajeev K.; Gailey, Alycia; Lindau, Manfred; Apsel, Alyssa B.

    2015-01-01

    A 30-μW wireless fast-scan cyclic voltammetry monitoring integrated circuit for ultra-wideband (UWB) transmission of dopamine release events in freely-behaving small animals is presented. On-chip integration of analog background subtraction and UWB telemetry yields a 32-fold increase in resolution versus standard Nyquist-rate conversion alone, near a four-fold decrease in the volume of uplink data versus single-bit, third-order, delta-sigma modulation, and more than a 20-fold reduction in transmit power versus narrowband transmission for low data rates. The 1.5-mm2 chip, which was fabricated in 65-nm CMOS technology, consists of a low-noise potentiostat frontend, a two-step analog-to-digital converter (ADC), and an impulse-radio UWB transmitter (TX). The duty-cycled frontend and ADC/UWB-TX blocks draw 4 μA and 15 μA from 3-V and 1.2-V supplies, respectively. The chip achieves an input-referred current noise of 92 pArms and an input current range of ±430 nA at a conversion rate of 10 kHz. The packaged device operates from a 3-V coin-cell battery, measures 4.7 × 1.9 cm2, weighs 4.3 g (including the battery and antenna), and can be carried by small animals. The system was validated by wirelessly recording flow-injection of dopamine with concentrations in the range of 250 nM to 1 μM with a carbon-fiber microelectrode (CFM) using 300-V/s FSCV. PMID:26057983

  6. A Wireless FSCV Monitoring IC With Analog Background Subtraction and UWB Telemetry.

    Science.gov (United States)

    Dorta-Quiñones, Carlos I; Wang, Xiao Y; Dokania, Rajeev K; Gailey, Alycia; Lindau, Manfred; Apsel, Alyssa B

    2016-04-01

    A 30-μW wireless fast-scan cyclic voltammetry monitoring integrated circuit for ultra-wideband (UWB) transmission of dopamine release events in freely-behaving small animals is presented. On-chip integration of analog background subtraction and UWB telemetry yields a 32-fold increase in resolution versus standard Nyquist-rate conversion alone, near a four-fold decrease in the volume of uplink data versus single-bit, third-order, delta-sigma modulation, and more than a 20-fold reduction in transmit power versus narrowband transmission for low data rates. The 1.5- mm(2) chip, which was fabricated in 65-nm CMOS technology, consists of a low-noise potentiostat frontend, a two-step analog-to-digital converter (ADC), and an impulse-radio UWB transmitter (TX). The duty-cycled frontend and ADC/UWB-TX blocks draw 4 μA and 15 μA from 3-V and 1.2-V supplies, respectively. The chip achieves an input-referred current noise of 92 pA(rms) and an input current range of ±430 nA at a conversion rate of 10 kHz. The packaged device operates from a 3-V coin-cell battery, measures 4.7 × 1.9 cm(2), weighs 4.3 g (including the battery and antenna), and can be carried by small animals. The system was validated by wirelessly recording flow-injection of dopamine with concentrations in the range of 250 nM to 1 μM with a carbon-fiber microelectrode (CFM) using 300-V/s FSCV.

  7. Redefining the Whole: Common Errors in Elementary Preservice Teachers' Self-Authored Word Problems for Fraction Subtraction

    Science.gov (United States)

    Dixon, Juli K.; Andreasen, Janet B.; Avila, Cheryl L.; Bawatneh, Zyad; Deichert, Deana L.; Howse, Tashana D.; Turner, Mercedes Sotillo

    2014-01-01

    A goal of this study was to examine elementary preservice teachers' (PSTs) ability to contextualize and decontextualize fraction subtraction by asking them to write word problems to represent fraction subtraction expressions and to choose prewritten word problems to support given fraction subtraction expressions. Three themes emerged from the…

  8. A Digital Loudspeaker: Experimental Construction

    Directory of Open Access Journals (Sweden)

    P. Valoušek

    2006-01-01

    Full Text Available To verify the principal functionality of a digital loudspeaker the experimental construction of a digital loudspeaker was designed. This system consists of signal processing unit and transducer array. Both parts offer 8-bit precision and wide a spectrum of sampling frequencies. The signal processing unit is based on a programmable logic device which provides a flexible system for preparing a driving signal. The transducer array is formed by conventional dynamic transducers arranged in a circle. The initial measurements and listening tests provide acceptable results that are valuable for further digital loudspeaker developments. 

  9. All digital pulsewidth control loop

    Science.gov (United States)

    Huang, Hong-Yi; Jan, Shiun-Dian; Pu, Ruei-Iun

    2013-03-01

    This work presents an all-digital pulsewidth control loop (ADPWCL). The proposed system accepts a wide range of input duty cycles and performs a fast correction to the target output pulsewidth. An all-digital delay-locked loop (DLL) with fast locking time using a simplified time to digital converter and a new differential two-step delay element is proposed. The area of the delay element is much smaller than that in conventional designs, while having the same delay range. A test chip is verified in a 0.18-µm CMOS process. The measured duty cycle ranges from 4% to 98% with 7-bit resolution.

  10. Comparação entre os exames radiográficos convencional e digitalizado em relação ao plano de tratamento de superfícies oclusais Comparison between digitized and conventional radiography in the treatment plan for occlusal surfaces

    Directory of Open Access Journals (Sweden)

    Dione Dias TORRIANI

    2000-09-01

    Full Text Available O objetivo deste estudo foi comparar as decisões de tratamento restaurador de superfícies oclusais, sem cavitação, quando realizadas através dos aspectos clínicos e radiográficos, convencional e digitalizado. Foram examinados, 33 sítios das superfícies oclusais de 30 molares permanentes extraídos, com e sem pigmentação. O plano de tratamento para cada região foi realizado por 5 cirurgiões-dentistas, professores universitários, utilizando dois tipos de exames: exame visual de fotografias e radiografia interproximal convencional (IV + RXC; e exame visual de fotografias e radiografia digitalizada (IV + DIGORA. O padrão de validação para os planos de tratamento foi realizado através do aspecto histológico. A sensibilidade em determinar a não-necessidade de tratamento restaurador foi, em média, tanto para a IV + RXC quanto para a IV + DIGORA, de 0,23. A especificidade foi, em média, de 0,83 e 0,86, para a IV + RXC e IV + DIGORA, respectivamente. Quando comparou-se os planos de tratamento intra-examinadores, não foi encontrada diferença estatisticamente significante à nível de 5%. Baseado nestes dados, pode-se concluir que os métodos radiográficos, convencional e digitalizado, não demonstraram diferenças na efetividade da determinação do plano de tratamento de superfícies oclusais sem cavitação.The objective of this study was to compare the treatment plan decisions made for intact occlusal surfaces using different diagnostic tools. Clinical photographs and either conventional or digitized radiographs were used to evaluate 33 regions of the occlusal surfaces of 30 extracted permanent molars. The teeth had regions with and without pigmentation. The treatment plan decisions were made by 5 dental faculty members using the two examination methods: 1 visual exam of photographs and conventional radiographs (IV+RXC; and 2 visual exam of photographs and digitized radiographs (IV+DIGORA. The regions were assigned a value of 0

  11. Exponential Renormalization II: Bogoliubov's R-operation and momentum subtraction schemes

    CERN Document Server

    Ebrahimi-Fard, Kurusch

    2011-01-01

    We develop further the recently introduced exponential method for renormalisation in perturbative quantum field theory. It turns out that exponential renormalisation provides a meaningful recursive method in the context of renormalisation using momentum subtraction schemes. We explore in detail its link to Bogoliubov's R-operation. Our results shed new light on classical ideas, such as the role of oversubtractions in the BPHZ method. They also suggest that the ambiguities of the renormalisation process carry, besides a physical structure (encoded, e.g. in the RG equations and the choice of subtraction points in momentum subtraction schemes), an interesting, though purely algebraic structure.

  12. Exponential renormalisation. II. Bogoliubov's R-operation and momentum subtraction schemes

    Energy Technology Data Exchange (ETDEWEB)

    Ebrahimi-Fard, Kurusch [Instituto de Ciencias Matematicas, C/ Nicolas Cabrera, no. 13-15, 28049 Madrid (Spain); Patras, Frederic [Laboratoire J.-A. Dieudonne UMR 6621, CNRS, Parc Valrose, 06108 Nice Cedex 02 (France)

    2012-08-15

    This article aims at advancing the recently introduced exponential method for renormalisation in perturbative quantum field theory. It is shown that this new procedure provides a meaningful recursive scheme in the context of the algebraic and group theoretical approach to renormalisation. In particular, we describe in detail a Hopf algebraic formulation of Bogoliubov's classical R-operation and counterterm recursion in the context of momentum subtraction schemes. This approach allows us to propose an algebraic classification of different subtraction schemes. Our results shed light on the peculiar algebraic role played by the degrees of Taylor jet expansions, especially the notion of minimal subtraction and oversubtractions.

  13. Digital Insights

    DEFF Research Database (Denmark)

    Knudsen, Gry Høngsmark

    , by incorporating media as both channel, frame, and apparatus for advertising response, the dissertation brings into attention that more aspects than the text-reader relationship influence ad response. Finally, the dissertation proposes the assemblage approach for exploring big data in consumer culture research......This dissertation forwards the theory of digital consumer-response as a perspective to examine how digital media practices influence consumers’ response to advertising. Digital consumer-response is a development of advertising theory that encompasses how consumers employ their knowledge...... and practices with digital media, when they meet and interpret advertising. Through studies of advertising response on YouTube and experiments with consumers’ response to digitally manipulated images, the dissertation shows how digital media practices facilitate polysemic and socially embedded advertising...

  14. WAXS fat subtraction model to estimate differential linear scattering coefficients of fatless breast tissue: Phantom materials evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Robert Y., E-mail: rx-tang@laurentian.ca [Biomolecular Sciences Program, Laurentian University, 935 Ramsey Lake Road, Sudbury, Ontario P3E 2C6 (Canada); Laamanen, Curtis, E-mail: cx-laamanen@laurentian.ca; McDonald, Nancy, E-mail: mcdnancye@gmail.com [Department of Physics, Laurentian University, 935 Ramsey Lake Road, Sudbury, Ontario P3E 2C6 (Canada); LeClair, Robert J., E-mail: rleclair@laurentian.ca [Department of Physics, Laurentian University, 935 Ramsey Lake Road, Sudbury, Ontario P3E 2C6, Canada and Biomolecular Sciences Program, Laurentian University, 935 Ramsey Lake Road, Sudbury, Ontario P3E 2C6 (Canada)

    2014-05-15

    measure μ{sub s} of homogeneous samples was quantitatively accurate. Simple WAXS models predicted the probabilities for specific x-ray scattering to occur from heterogeneous biopsies. The fat subtraction model can allow μ{sub s} signals of breast cancer and fibroglandular tissue to be compared without the effects of fat provided there is an independent measurement of the fat volume fraction ν{sub f}. Future work will consist of devising a quantitative x-ray digital imaging method to estimate ν{sub f} in ex vivo breast samples.

  15. Digital Forensics

    OpenAIRE

    Ψευτέλης, Αθανάσιος Δημήτρης

    2013-01-01

    A reprint from American Scientist the magazine of Sigma Xi, The Scientific Research Society Since the 1980s, computers have had increasing roles in all aspects of human life—including an involvement in criminal acts. This development has led to the rise of digital forensics, the uncovering and examination of evidence located on all things electronic with digital storage, including computers, cell phones, and networks. Digital forensics researchers and practitione...

  16. A 5.8nW, 45ppm/°C On-Chip CMOS Wake-up Timer Using a Constant Charge Subtraction Scheme.

    Science.gov (United States)

    Jeong, Seokhyeon; Lee, Inhee; Blaauw, David; Sylvester, Dennis

    2014-09-01

    This work presents an ultra-low power oscillator designed for wake-up timers in compact wireless sensors. A constant charge subtraction scheme removes continuous comparator delay from the oscillation period, which is the source of temperature dependence in conventional RC relaxation oscillators. This relaxes comparator design constraints, enabling low power operation. In 0.18µm CMOS, the oscillator consumes 5.8nW at room temperature with temperature stability of 45ppm/°C (-10°C to 90°C) and 1%V line sensitivity.

  17. Digital audio and video broadcasting by satellite

    Science.gov (United States)

    Yoshino, Takehiko

    In parallel with the progress of the practical use of satellite broadcasting and Hi-Vision or high-definition television technologies, research activities are also in progress to replace the conventional analog broadcasting services with a digital version. What we call 'digitalization' is not a mere technical matter but an important subject which will help promote multichannel or multimedia applications and, accordingly, can change the old concept of mass media, such as television or radio. NHK Science and Technical Research Laboratories has promoted studies of digital bandwidth compression, transmission, and application techniques. The following topics are covered: the trend of digital broadcasting; features of Integrated Services Digital Broadcasting (ISDB); compression encoding and transmission; transmission bit rate in 12 GHz band; number of digital TV transmission channels; multichannel pulse code modulation (PCM) audio broadcasting system via communication satellite; digital Hi-Vision broadcasting; and development of digital audio broadcasting (DAB) for mobile reception in Japan.

  18. Digital displacements

    DEFF Research Database (Denmark)

    Pors, Anja Svejgaard

    2014-01-01

    In recent years digital reforms are being introduced in the municipal landscape of Denmark. The reforms address the interaction between citizen and local authority. The aim is, that by 2015 at least 80 per cent of all correspondence between citizens and public authority will be transmitted through...... digital interface. However, the transformation of citizen services from traditional face-to-face interaction to digital self-service gives rise to new practices; some citizens need support to be able to manage self-service through digital tools. A mixture of support and teaching, named co...

  19. Contrast-enhanced digital mammography

    Energy Technology Data Exchange (ETDEWEB)

    Dromain, Clarisse [Department of Radiology, Institut Gustave-Roussy, 39, rue Camille Desmoulins, 94805 Villejuif Cedex (France)], E-mail: dromain@igr.fr; Balleyguier, Corinne; Adler, Ghazal [Department of Radiology, Institut Gustave-Roussy, 39, rue Camille Desmoulins, 94805 Villejuif Cedex (France); Garbay, Jean Remi [Department of Surgery, Institut Gustave-Roussy, 39, rue Camille Desmoulins, 94805 Villejuif Cedex (France); Delaloge, Suzette [Department of Medicine, Institut Gustave-Roussy, 39, rue Camille Desmoulins, 94805 Villejuif Cedex (France)

    2009-01-15

    CEDM is a recent development of digital mammography using the intra-venous injection of an iodinated contrast agent in conjunction with a mammography examination. Two techniques have been developed to perform CEDM examinations: the temporal subtraction technique with acquisition of high-energy images before and after contrast medium injection and the dual energy technique with acquisition of a pair of low and high-energy images only after contrast medium injection. The temporal subtraction technique offered the possibility to analyze the kinetic curve of enhancement of breast lesions, similarly to breast MRI. The dual energy technique do not provide information about the kinetic of tumor enhancement but allows the acquisition of multiples views of the same breast or bilateral examination and is less sensitive to patient motion than temporal CEDM. Initial clinical experience has shown the ability of CEDM to map the distribution of neovasculature induced by cancer using mammography. Moreover, previous studies have shown a superiority of MX + CEDM, either for the assessment of the probability of malignancy than for BIRADS assessment comparing to MX alone. The potential clinical applications are the clarification of mammographically equivocal lesions, the detection of occult lesions on standard mammography, particularly in dense breast, the determination of the extent of disease, the assessment of recurrent disease and the monitoring of the response to chemotherapy. CEDM should result in a simple way to enhance the detection and the characterization of breast lesions.

  20. A task-based comparison of two reconstruction algorithms for digital breast tomosynthesis

    Science.gov (United States)

    Mahadevan, Ravi; Ikejimba, Lynda C.; Lin, Yuan; Samei, Ehsan; Lo, Joseph Y.

    2014-03-01

    Digital breast tomosynthesis (DBT) generates 3-D reconstructions of the breast by taking X-Ray projections at various angles around the breast. DBT improves cancer detection as it minimizes tissue overlap that is present in traditional 2-D mammography. In this work, two methods of reconstruction, filtered backprojection (FBP) and the Newton-Raphson iterative reconstruction were used to create 3-D reconstructions from phantom images acquired on a breast tomosynthesis system. The task based image analysis method was used to compare the performance of each reconstruction technique. The task simulated a 10mm lesion within the breast containing iodine concentrations between 0.0mg/ml and 8.6mg/ml. The TTF was calculated using the reconstruction of an edge phantom, and the NPS was measured with a structured breast phantom (CIRS 020) over different exposure levels. The detectability index d' was calculated to assess image quality of the reconstructed phantom images. Image quality was assessed for both conventional, single energy and dual energy subtracted reconstructions. Dose allocation between the high and low energy scans was also examined. Over the full range of dose allocations, the iterative reconstruction yielded a higher detectability index than the FBP for single energy reconstructions. For dual energy subtraction, detectability index was maximized when most of the dose was allocated to the high energy image. With that dose allocation, the performance trend for reconstruction algorithms reversed; FBP performed better than the corresponding iterative reconstruction. However, FBP performance varied very erratically with changing dose allocation. Therefore, iterative reconstruction is preferred for both imaging modalities despite underperforming dual energy FBP, as it provides stable results.

  1. Digital hum filtering

    Science.gov (United States)

    Knapp, R.W.; Anderson, N.L.

    1994-01-01

    Data may be overprinted by a steady-state cyclical noise (hum). Steady-state indicates that the noise is invariant with time; its attributes, frequency, amplitude, and phase, do not change with time. Hum recorded on seismic data usually is powerline noise and associated higher harmonics; leakage from full-waveform rectified cathodic protection devices that contain the odd higher harmonics of powerline frequencies; or vibrational noise from mechanical devices. The fundamental frequency of powerline hum may be removed during data acquisition with the use of notch filters. Unfortunately, notch filters do not discriminate signal and noise, attenuating both. They also distort adjacent frequencies by phase shifting. Finally, they attenuate only the fundamental mode of the powerline noise; higher harmonics and frequencies other than that of powerlines are not removed. Digital notch filters, applied during processing, have many of the same problems as analog filters applied in the field. The method described here removes hum of a particular frequency. Hum attributes are measured by discrete Fourier analysis, and the hum is canceled from the data by subtraction. Errors are slight and the result of the presence of (random) noise in the window or asynchrony of the hum and data sampling. Error is minimized by increasing window size or by resampling to a finer interval. Errors affect the degree of hum attenuation, not the signal. The residual is steady-state hum of the same frequency. ?? 1994.

  2. Dynamic graded subtraction: a simple method to background correct and display multicompartmental radiopharmaceutical scintigrams

    Energy Technology Data Exchange (ETDEWEB)

    Tuscan, M.J.; Wahl, R.L.; Botti, J.

    1985-09-01

    A common procedure to enhance the localization of a poorly localized radiopharmaceutical is to mimic and subtract its undesirable component with a second radionuclide of a different photopeak that is physiologic nonspecific. Determination of the exact amount of the nonspecific radionuclide to subtract in a single step, however, is difficult. The authors describe the use of a simple method to enhance an image of a poorly localized radiopharmaceutical by incrementally subtracting another image of a specific radiopharmaceutical that mimics the objectionable image data and displays the corrected image series in cinematic mode. This method of image correction and dynamic display may be useful for a variety of procedures in which there is a significant nonspecific component of the radiotracer such as in radiolabeled antibodies, or to perform selective compartmental or organ subtraction in the case of a mixed specificity radiopharmaceutical.

  3. Adaptive multiple subtraction with wavelet-based complex unary Wiener filters

    CERN Document Server

    Ventosa, Sergi; Huard, Irène; Pica, Antonio; Rabeson, Hérald; Ricarte, Patrice; Duval, Laurent

    2011-01-01

    Multiple attenuation is a crucial task in seismic data processing because multiples usually cover primaries from fundamental reflectors. Predictive multiple suppression methods remove these multiples by building an adapted model, aiming at being subtracted from the original signal. However, before the subtraction is applied, a matching filter is required to minimize amplitude differences and misalignments between actual multiples and their prediction, and thus to minimize multiples in the input dataset after the subtraction. In this work we focus on the subtraction element. We propose an adaptive multiple removal technique in a 1-D complex wavelet frame combined with a non-stationary adaptation performed via single-sample (unary) Wiener filters, consistently estimated on overlapping windows in the transformed domain. This approach greatly simplifies the matching filter estimation and, despite its simplicity, compares promisingly with standard adaptive 2-D methods, both in terms of results and retained speed a...

  4. Superconductor Digital-RF Transceiver Components

    Science.gov (United States)

    2006-01-01

    high-power amplifier (HPA). The diagram also shows a dynamic digital equalizer, a digital predistortion module that is combined with the DAC to...intermodulation distortion, especially near their maximum output powers. Unlike conventional baseband or intermediate frequency (IF) predistorters ...which are limited to narrowband correction of slowly varying non- linearities, our RF predistorter can correct instantaneous, signal-dependent

  5. Digital Libraries

    CERN Document Server

    Papy, Fabrice

    2008-01-01

    Of vital interest to all librarians and information specialists, this book presents all aspects of the effects of digitization of today's and tomorrow's libraries. From social to technical issues, Digital Libraries includes chapters on the growth of the role of librarian, the reader experience, cataloging, search engines, OPAC, law, ergonomic studies, and the future of libraries.

  6. Digital Audiobooks:

    DEFF Research Database (Denmark)

    Have, Iben; Pedersen, Birgitte Stougaard

    Audiobooks are rapidly gaining popularity with widely accessible digital downloading and streaming services. The paper is framing how the digital audiobook expands and changes the target groups for book publications and how it as an everyday activity is creating new reading experiences, places...

  7. Tailed pooled suppression subtractive hybridization (PSSH) adaptors do not alter efficiency.

    Science.gov (United States)

    Gerrish, Robert S; Gill, Steven R

    2010-11-01

    Suppression Subtractive Hybridization (SSH) and its derivative, Pooled Suppression Subtractive hybridization (PSSH), are powerful tools used to study variances larger than ~100 bp in prokaryotic genome structure. The initial steps involve ligating an oligonucleotide of known sequence (the "adaptor") to a fragmented genome to facilitate amplification, subtraction and downstream sequencing. SSH results in the creation of a library of unique DNA fragments which have been traditionally analyzed via Sanger sequencing. Numerous next generation sequencing technologies have entered the market yet SSH is incompatible with these platforms. This is due to the high level of sequence conservation of the oligonucleotide used for SSH. This rigid adherence is partly because it has yet to be determined if alteration of this oligonucleotide will have a deleterious impact on subtraction efficiency. The subtraction occurs when non-unique fragments are inhibited by a secondary self-pairing structure which requires exact nucleotide sequence. We determine if appending custom sequence to the 5' terminal ends of these oligonucleotides during the nested PCR stages of PSSH will reduce subtraction efficiency. We compare a pool of ten S. aureus clinical isolates with a standard PSSH and custom tailed-PSSH. We detected no statistically significant difference between their subtraction efficiencies. Our observations suggest that the adaptor's terminal ends may be labeled during the nested PCR step. This produces libraries labeled with custom sequence. This does not lead to loss of subtraction efficiency and would be invaluable for groups wishing to combine SSH or PSSH with their own downstream applications, such as a high throughput sequencing platform.

  8. Digital immediate dentures treatment: A clinical report of two patients.

    Science.gov (United States)

    Neumeier, Toni Tien; Neumeier, Harold

    2016-09-01

    The use of computer-aided engineering (CAE) and computer-aided design and computer-aided manufacturing (CAD-CAM) technology to fabricate complete dentures was introduced in 2011. Clinical procedures for digital immediate dentures can be identical to those for conventional immediate dentures and can be simplified by leaving all remaining dentition until the time of extraction and denture placement. Through the digital process, a single digital design and a definitive digital record are created which can be used to fabricate the immediate digital denture and surgical reduction guide for alveoloplasty. Digital immediate dentures can be relined using the same process as for conventional dentures. The definitive digital dentures can be fabricated with a reline impression and new centric relation record, using the existing digital immediate denture without additional clinical procedures. Providing patients with digital immediate dentures is a viable trend.

  9. Diversity Suppression-Subtractive Hybridization Array for Profiling Genomic DNA Polymorphisms

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Genomic DNA polymorphisms are very useful for tracing genetic traits and studying biological diversity among species. Here, we present a method we call the "diversity suppression-subtractive hybridization array" for effectively profiling genomic DNA polymorphisms. The method first obtains the subtracted gDNA fragments between any two species by suppression subtraction hybridization (SSH) to establish a subtracted gDNA library,from which diversity SSH arrays are created with the selected subtracted clones. The diversity SSH array hybridizes with the DIG-labeled genomic DNA of the organism to be assayed. Six closely related Dendrobium species were studied as model samples. Four Dendrobium species as testers were used to perform SSH. A total of 617 subtracted positive clones were obtained from four Dendrobium species, and the average ratio of positive clones was 80.3%. We demonstrated that the average percentage of polymorphic fragments of pairwise comparisons of four Dendrobium species was up to 42.4%. A dendrogram of the relatedness of six Dendrobium species was produced according to their polymorphic profiles. The results revealed that the diversity SSH array is a highly effective platform for profiling genomic DNA polymorphisms and dendrograms.

  10. Young children's use of derived fact strategies in addition and subtraction

    Directory of Open Access Journals (Sweden)

    Ann eDowker

    2014-01-01

    Full Text Available 44 children between 6;0 and 7;11 took part in a study of derived fact strategy use. They were assigned to addition and subtraction levels on the basis of calculation pretests. They were then given Dowker’s (1998 test of derived fact strategies in addition, involving strategies based on the Identity, Commutativity, Addend + 1,Addend −1, and addition/subtraction Inverse principles; and test of derived fact strategies in subtraction, involving strategies based on the Identity, Minuend +1, Minuend -1, Subtrahend +1, Subtrahend -1, Complement and addition/subtraction Inverse principles. The exact arithmetic problems given varied according to the child’s previously assessed calculation level and were selected to be just a little too difficult for the child to solve unaided. Children were given the answer to a problem and then asked to solve another problem that could be solved quickly by using this answer, together with the principle being assessed. The children also took the WISC Arithmetic subtest. Strategies differed greatly in difficulty, with Identity being the easiest, and the Inverse and Complement principles being most difficult. The Subtrahend + 1 and Subtrahend – 1 problems often elicited incorrect strategies based on an overextension of the principles of addition to subtraction. It was concluded that children may have difficulty with understanding and applying the relationships between addition and subtraction. Derived fact strategy use was significantly related to both calculation level and to WISC Arithmetic scaled score.

  11. Value of blood-pool subtraction in cardiac indium-111-labeled platelet imaging

    Energy Technology Data Exchange (ETDEWEB)

    Machac, J.; Vallabhajosula, S.; Goldman, M.E.; Goldsmith, S.J.; Palestro, C.; Strashun, A.; Vaquer, R.; Phillips, R.A.; Fuster, V. (Mt. Sinai Medical Center, New York, NY (USA))

    1989-09-01

    Blood-pool subtraction has been proposed to enhance {sup 111}In-labeled platelet imaging of intracardiac thrombi. We tested the accuracy of labeled platelet imaging, with and without blood-pool subtraction, in ten subjects with cardiac thrombi of varying age, eight with endocarditis being treated with antimicrobial therapy and ten normal controls. Imaging was performed early after labeled platelet injection (24 hr or less) and late (48 hr or more). Blood-pool subtraction was carried out. All images were graded subjectively by four experienced, blinded readers. Detection accuracy was measured by the sensitivity at three fixed levels of specificity estimated from receiver operator characteristic curve analysis and tested by three-way analysis of variance. Detection accuracy was generally improved on delayed images. Blood-pool subtraction did not improve accuracy. Although blood-pool subtraction increased detection sensitivity, this was offset by decreased specificity. For this population studied, blood-pool subtraction did not improve subjective detection of abnormal platelet deposition by 111In platelet imaging.

  12. The sixth data release of the Sloan Digital Sky Survey

    OpenAIRE

    Adelman-McCarthy, Jennifer K.; Agüeros, Marcel A.; Allam, Sahar S.; Prieto, Carlos Allende; Anderson, Kurt S. J.; Anderson, Scott F.; Annis, James; Bahcall, Neta A.; Bailer-Jones, C. A. L.; Baldry, Ivan K.; Barentine, J. C.; Bassett, Bruce A.; Becker, Andrew C.; Beers, Timothy C.; Bell, Eric F.

    2008-01-01

    This paper describes the Sixth Data Release of the Sloan Digital Sky Survey. With this data release, the imaging of the northern Galactic cap is now complete. The survey contains images and parameters of roughly 287 million objects over 9583 deg^2, including scans over a large range of Galactic latitudes and longitudes. The survey also includes 1.27 million spectra of stars, galaxies, quasars, and blank sky (for sky subtraction) selected over 7425 deg^2. This release includes much more stella...

  13. Conventional cerebrospinal fluid scanning

    Energy Technology Data Exchange (ETDEWEB)

    Schicha, H.

    1985-06-01

    Conventional cerebrospinal fluid scanning (CSF scanning) today is mainly carried out in addition to computerized tomography to obtain information about liquor flow kinetics. Especially in patients with communicating obstructive hydrocephalus, CSF scanning is clinically useful for the decision for shunt surgery. In patients with intracranial cysts, CSF scanning can provide information about liquor circulation. Further indications for CSF scanning include the assessment of shunt patency especially in children, as well as the detection and localization of cerebrospinal fluid leaks.