Tumor transport physiology: implications for imaging and imaging-guided therapy.
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Contrast Media↗
Biomedical subjects
B S Kuszyk
Publications and source records attributed to B S Kuszyk.
Osseous anatomy of the lumbosacral spine in Marfan syndrome.
STUDY DESIGN: This study examines pedicle widths, laminar thicknesses, and scalloping values for lumbosacral spine elements in Marfan volunteers. Comparisons were made between these measurements and norms as well as measurements between Marfan patients with and without dural ectasia. OBJECTIVES: To determine if the lumbosacral vertebral elements are altered in the patient with Marfan syndrome. SUMMARY OF BACKGROUND DATA: Several abnormalities have been noted in Marfan lumbar spine, including pedicular attenuation and widened interpediculate distances. This may be due to abnormalities of growth or presence of dural ectasia. Given the large numbers of Marfan patients requiring spinal surgery and the high postoperative failure rate, better understanding of the bony anatomy of Marfan lumbar spine is necessary, especially if use of instrumentation is anticipated. METHODS: Thirty-two volunteers with Marfan syndrome based on the Ghent criteria underwent spiral computed tomography of the lumbosacral spine. Images were evaluated for dural ectasia, and measurements of pedicle width, laminar thickness, and vertebral scalloping were made. RESULTS: Pedicle widths and laminar thicknesses were significantly smaller in Marfan patients at all levels (P<0.001). Mean pedicle widths at L1-L3 were smaller than the smallest available pedicle screw (5 mm). In Marfan patients with dural ectasia, laminar thickness from L5-S2 and pedicle widths at all lumbar levels were significantly reduced (P<0.01). Vertebral scalloping at S1 was significantly greater in Marfan patients with dural ectasia (P = 0.02). CONCLUSION: Lumbar pedicle width and laminar thickness are significantly reduced in Marfan individuals. Those with dural ectasia demonstrate increased bony erosion of anterior and posterior elements of lumbosacral spine. Preoperative planning and routine computed tomography scans are recommended when operating on Marfan lumbosacral spine.
Adult↗
Dural ectasia is associated with back pain in Marfan syndrome.
STUDY DESIGN: A cross-sectional age- and sex-matched study comparing the prevalence and size of dural ectasia in two groups of patients with Marfan syndrome. Group I comprised patients with moderate to severe back pain and Group II comprised patients without back pain. OBJECTIVES: To determine whether the presence and size of dural ectasia is associated with back pain in patients with Marfan syndrome. SUMMARY OF BACKGROUND DATA: Dural ectasia is present in more than 60% of patients with Marfan syndrome. Moderate to severe back pain is present in more than 50% of patients with Marfan syndrome. Most cases of significant low back pain in patients with Marfan syndrome do not have a clear cause. It would be useful for the clinician to know whether dural ectasia may be a cause of back pain in patients with Marfan syndrome with no other source. METHODS: Thirty two volunteers aged 30-50 with Marfan syndrome were enrolled as age- and sex-matched pairs with significant back pain (Group I) and without back pain (Group II). A completed questionnaire, physical examination, and magnetic resonance image of the lumbosacral spine were obtained. Dural volume caudal to L5 was calculated from the magnetic resonance data by specially designed software. RESULTS: Dural ectasia was present in 76% of the patients in Group I, and 41% of the patients in Group II. The proportion of patients with dural ectasia was significantly higher in Group I. Furthermore, the mean dural volume was significantly higher in Group I, and a significant correlation between dural volume and Oswestry pain score was noted. CONCLUSIONS: The presence and size of dural ectasia are associated with back pain in the Marfan syndrome. However, a high prevalence of dural ectasia (41%) exists even in patients with Marfan syndrome without back pain. The mere presence of dural ectasia therefore does not necessarily mean the patient will be symptomatic even though the two are associated.
Adult↗
Local tumor recurrence following hepatic cryoablation: radiologic-histopathologic correlation in a rabbit model.
PURPOSE: To use radiologic-histopathologic correlation in an animal model to distinguish normal postoperative findings from evidence of residual tumor after cryoablation of malignant hepatic tumors. MATERIALS AND METHODS: Hepatic cryoablation was performed in 12 rabbits with VX2 tumors and in two healthy rabbits. Nonenhanced and dynamic contrast material-enhanced computed tomography (CT) and magnetic resonance (MR) imaging and power and color Doppler flow ultrasonography (US) were performed 7-8 days after cryoablation. Histopathologic findings were correlated with imaging findings. RESULTS: Twenty tumors of 5-20 mm (mean, 10 mm) and seven areas of normal liver were treated with cryolesions of 11-21 mm (mean, 15 mm). All cryolesions exhibited arterial phase rim enhancement at CT and MR imaging, and 13 (57%) of 23 lesions demonstrated peripheral flow at US because of granulation tissue. There was macroscopic recurrence in 15 (75%) of 20 treated tumors; 14 (93%) appeared as peripheral nodularity with low-grade enhancement. Necrotic tissue did not enhance. Intact vessels extended up to 6 mm inside cryolesion margins and caused focal internal enhancement and Doppler flow. Areas of high signal intensity on T2-weighted MR images correlated with liquefaction necrosis, granulation tissue, and tumor. CONCLUSION: In this animal model, recurrent tumor typically appeared as focal nodules at the cryolesion periphery. Rim and central foci of enhancement, Doppler flow, and increased signal intensity on T2-weighted MR images can be normal findings after hepatic cryoablation.
Animals↗
1999 ARRS Executive Council Award. Contrast-enhanced CT of small hypovascular hepatic tumors: effect of lesion enhancement on conspicuity in rabbits. American Roentgen Ray Society.
OBJECTIVE: The purpose of this study was to evaluate the effect of lesion enhancement on the conspicuity of small hypovascular hepatic tumors in an animal model. MATERIALS AND METHODS: Seven VX2 hepatic tumors in five rabbits were imaged. Dynamic contrast-enhanced CT was performed at a single level centered over the lesions at 5-sec intervals for 119 sec after injection of 2 ml/kg i.v. contrast material at 2 ml/sec. Attenuation was measured over time within regions of interest in the tumor and normal liver, aorta, inferior vena cava, and portal vein. Lesion conspicuity, defined as the difference between the attenuation of the uninvolved liver and neoplasm, was calculated. RESULTS: The mean diameter of the tumors on CT was 10 mm (range, 6-15 mm). The tumors appeared as low-attenuation lesions with progressive enhancement during the arterial phase and early portal phase. Peak mean lesion attenuation was 60 +/- 27 H (enhancement, 23 H) at 64 sec. Peak mean lesion conspicuity was 80 +/- 18 H at 39 sec, occurring 10 sec before the peak mean hepatic attenuation of 135 +/- 15 H (enhancement, 67 H) at 49 sec. Relative lesion conspicuity paralleled relative enhancement of the liver throughout the imaging period. CONCLUSION: Although low-level tumor enhancement during the arterial phase and early portal phase reduced the conspicuity of small hypovascular tumors in this animal model, our results support the use of maximum liver enhancement as a marker for peak lesion conspicuity.
Animals↗
CT of primary cystic pancreatic neoplasms: can CT be used for patient triage and treatment?
OBJECTIVE: The purpose of this study was to determine whether CT can be used to distinguish serous cystadenomas from mucinous cystadenomas or cystadenocarcinomas of the pancreas and play an enhanced role in patient triage and treatment. MATERIALS AND METHODS: A blinded retrospective analysis of CT scans from 50 patients with pathologically proven primary cystic pancreatic neoplasms was performed independently by three radiologists. Using classic CT criteria as reported in the literature, each tumor was categorized as definitely serous, mucinous, or indeterminate. Tumor location, size, presence of calcification, and size of largest cyst were recorded. Data for each reviewer were analyzed independently. Consensus data were then subjected to multivariate logistic regression analysis. RESULTS: The ability of our reviewers to diagnose serous neoplasms ranged from 23% to 41%. Eight mucinous neoplasms were mistaken for serous tumors by two of the three reviewers. When consensus between at least two of the three reviewers was used for diagnosis, 27% of serous neoplasms were correctly diagnosed and all of the mucinous tumors were correctly identified as uncertain or mucinous, yielding the same clinical end point. For multivariate logistic regression analysis, a cyst smaller than 2 cm had a statistically significant association (p = 0.005) with serous tumors, and the presence of peripheral tumoral calcification had a statistically significant association (p = 0.01) with mucinous tumors. CONCLUSION: There is significant variability in the CT appearance of serous and mucinous neoplasms of the pancreas, making CT an insensitive tool for differentiating these tumors. All tumors with peripheral calcifications were identified as mucinous neoplasms.
Adult↗
Cryptococcoma of the sacrum.
Cryptococcoma of the sacrum was the initial presentation of systemic cryptococcosis in a patient on chronic steroid therapy for autoimmune hepatitis. The bone lesion was the only overt manifestation of systemic cryptococcal disease, which preceded other clinical manifestations and led to the subsequent diagnosis of systemic infection.
Adult↗
Renal artery stenosis: CT angiography--comparison of real-time volume-rendering and maximum intensity projection algorithms.
PURPOSE: To compare results of helical computed tomographic (CT) angiography with real-time interactive volume rendering (VR) to CT angiography with maximum intensity projection (MIP) for the detection of renal artery stenosis. MATERIALS AND METHODS: Twenty-five patients underwent both conventional and CT angiography of the renal arteries. Images were blindly reviewed after rendering with MIP and VR algorithms. MIP images were viewed in conjunction with axial CT images; VR models were evaluated in real time at the workstation without CT images. Findings in 50 main and 11 accessory renal arteries were categorized as normal or by degree of stenosis. RESULTS: All arteries depicted on conventional angiograms were visualized on MIP and VR images. Receiver operating characteristic (ROC) analysis for MIP and VIR images demonstrated excellent discrimination for the diagnosis of stenosis of at least 50% (area under the ROC curve, 0.96-0.99). Although sensitivity was not significantly different for VR and MIP (89% vs 94%, P > .1), specificity was greater with VR (99% vs 87%, P = .008 to .08). Stenosis of at least 50% was overestimated with CT angiography in four accessory renal arteries, but three accessory renal arteries not depicted at conventional angiography were depicted at CT angiography. CONCLUSION: In the evaluation of renal artery stenosis, CT angiography with VR is faster and more accurate than CT angiography with MIP. Accessory arteries not depicted with conventional angiography were depicted with both CT angiographic algorithms.
Adult↗
CT angiography with volume rendering for quantifying vascular stenoses: in vitro validation of accuracy.
OBJECTIVE: The purpose of this study was to evaluate the accuracy of CT angiography with volume rendering for quantifying vascular stenoses in vitro. MATERIALS AND METHODS: Vascular models with three degrees of stenosis (33%, 67%, and 83%) were imaged at three orientations to the axial plane (parallel, perpendicular, or 45 degrees ) using helical CT with 2-mm collimation and two pitches (1 or 2), two reconstruction intervals (1 or 2 mm), and two scan times (.75 or 1 sec). Diameter and percentage of stenosis were measured from volume renderings using full width at half maximum. Images were measured in two planes whenever resolution varied with direction. Statistical analysis was performed using analysis of variance. RESULTS: Mean absolute error of the measured percentage of stenosis was 7% (range, 0-27%). The actual percentage of stenosis and vessel orientation had the most significant effects on accuracy (p < .001). The measured percentage of stenosis was significantly less accurate with phantoms parallel to the axial plane than with other orientations (p < .001). Mean absolute error in the measured percentage of stenosis was 4% when the parallel-to-the-axial-plane orientation was excluded. Overlapping (1-mm) reconstructions were significantly more accurate than 2-mm reconstructions (p < .05) and direction of measurement significantly affected accuracy (p < .05), but these effects were secondary. CONCLUSION: CT angiography with volume rendering can accurately quantify vascular stenoses, but it is less accurate for vessels in the axial plane. With 2-mm collimation, vessel characteristics have greater effects on accuracy than do acquisition parameters.
Analysis of Variance↗
Epidermoid inclusion cysts seen on CT of a patient with Gardner's syndrome.
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Adult↗
Three-dimensional helical CT angiography in renal transplant recipients: a new problem-solving tool.
OBJECTIVE: Our objective was to describe the use of three-dimensional helical CT angiography for the evaluation of renal transplant recipients presenting with hypertension, graft dysfunction, or both after transplantation by evaluating the native and transplanted renal arteries in a single examination. CONCLUSION: Early results indicate that three-dimensional helical CT angiography of renal transplant recipients presenting with hypertension, graft dysfunction, or both after transplantation yields valuable information that can be used to guide further therapy.
Adult↗
Incidentally diagnosed Marchiafava-Bignami disease.
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Aged↗
3-D volume rendering as an anatomical reference for medical illustration.
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Anatomy, Artistic↗
Evaluating the potential and problems of three-dimensional computed tomography measurements of arterial stenosis.
Volume visualization is gaining widespread acceptance in medical applications. As its use increases, the issue of accuracy becomes critical. There have been very few studies examining the accuracy of volume rendering techniques. We studied the accuracy of hardware-assisted volume rendering for measurement of arterial stenosis in computed tomography (CT) data. The results of our study reveal that accurate measurements can be made from volume rendered CT data. However, error is present (absolute average error from 5.1% to 13.6%) and there is some variability, even for experts (standard deviation ranged from 4.8% to 15%). The evidence suggests that the choice of volume rendering (transfer function) parameters greatly affects the accuracy of the results. Accurate transfer function parameter selection is a difficult problem. Parameters that produce realistic images often provide inaccurate measurements. As the use of volume visualization grows and more inexperienced users begin using these tools for medical diagnosis and staging, new guidelines, aids, and techniques must be developed to ensure reliable, accurate visualization results.
Angiography↗
Technical aspects of CT angiography.
The basic tasks of spiral CT acquisition, image processing, and image display are the foundations underlying CT angiography regardless of the anatomic region of interest. Volume rendering is a rapidly emerging image processing technique for creating three-dimensional (3D) images from CT datasets, which has important advantages over other 3D rendering techniques including maximum intensity projection and surface rendering. This articles reviews the techniques that are commonly used in CT angiography and key considerations for optimization.
Angiography↗
Neurovascular applications of CT angiography.
CT angiography, which has important advantages over both MR and ultrasound, is rapidly becoming an important modality for noninvasive evaluation of the neurovasculature. This article discusses CT angiography techniques for imaging the neurovasculature, including spiral acquisition protocols and image processing techniques, with a focus on the use of volume rendering for three-dimensional visualization. The clinical results for CT angiography of the cervical carotid arteries, intracranial aneurysms, arteriovenous malformations, and emerging work in the evaluation of acute stroke are reviewed. Important areas of ongoing research also are described.
Aneurysm↗
Portal venous system thrombosis: helical CT angiography before transjugular intrahepatic portosystemic shunt creation.
PURPOSE: To evaluate the utility of helical computed tomographic (CT) angiography for depiction of thrombi in the portal venous system in patients under consideration for transjugular intrahepatic portosystemic shunt (TIPS) creation. MATERIALS AND METHODS: Contrast material-enhanced helical CT was performed before TIPS creation in 25 patients. Axial, multiplanar, and three-dimensional images were evaluated to determine whether thrombus was present in the portal system and whether TIPS creation was contraindicated. CT findings were confirmed at visceral angiography (n = 3), direct portography (n = 20), or duplex ultrasonography (n = 2). RESULTS: Ten (40%) of 25 patients, including 10 (56%) of 18 patients with refractory variceal hemorrhage, had thrombus in the portal venous system. Helical CT scans depicted thrombus in nine (90%) of 10 patients (95% confidence interval = 0.71, 1.00) and in 16 (94%) of 17 vessels (95% confidence interval = 0.83, 1.00), including the portal vein (eight of eight patients), splenic vein (three of four patients), and superior mesenteric vein (five of five patients). TIPS creation was canceled in four (16%) patients on the basis of CT findings. CONCLUSION: Thrombi in the portal venous system are common in patients with refractory variceal hemorrhage. Helical CT angiography is sensitive and specific for portal venous system thrombosis and can provide information that alters treatment in these patients.
Contraindications↗
An interactive computer-based tool for teaching the segmental anatomy of the liver: usefulness in the education of residents and fellows.
OBJECTIVE: The purpose of this study was to develop an interactive computer-based tool for teaching hepatic segment anatomy and to evaluate its usefulness for radiology education. CONCLUSION: An interactive computer-based teaching tool has been developed that effectively teaches the segmental anatomy of the liver to radiology residents and fellows who have a wide range of baseline knowledge of hepatic anatomy.
Computer-Assisted Instruction↗