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Biomedical subjects

B S Kuszyk

Publications and source records attributed to B S Kuszyk.

At least 37 records · Page 2Linked to original sources
PubMed1997

Intrahepatic cholangiocarcinoma: the role of imaging in detection and staging.

Intrahepatic cholangiocarcinoma can be divided into two basic categories: hilar and peripheral forms. This distinction has important implications in imaging evaluation, treatment, and prognosis. Cholangiocarcinoma often requires multiple imaging modalities for proper evaluation of potential resectability. In this review, we outline the role of CT, MR, ultrasound, cholangiography, and angiography in the evaluation of cholangiocarcinoma. We also describe newer techniques such as CT angiography, CT cholangiography, MR angiography, and MR cholangiography, and look at the possible future roles of these techniques.

Angiography↗
PubMed1996

Skeletal 3-D CT: advantages of volume rendering over surface rendering.

Both surface rendering and volume rendering have been extensively applied to CT data for 3-D visualization of skeletal pathology. The review illustrates potential limitations of each technique by directly comparing 3-D images of bone pathology created using volume rendering and surface rendering. Surface rendering show gross 3-D relationships most effectively, but suffer from more stairstep artifacts and fail to effectively display lesions hidden behind overlying bone or located beneath the bone cortex. Volume-rendering algorithms effectively show subcortical lesions, minimally displaced fractures, and hidden areas of interest with few artifacts. Volume algorithms show 3-D relationships with varying degrees of success depending on the degree of surface shading and opacity. While surface rendering creates more three-dimensionally realistic images of the bone surface, it may be of limited clinical utility due to numerous artifacts and the inability to show subcortical pathology. Volume rendering is a flexible 3-D technique that effectively displays a variety of skeletal pathology with few artifacts.

Algorithms↗
PubMed1996

CT angiography with volume rendering: advantages and applications in splanchnic vascular imaging.

The authors compared volume rendering with maximum intensity projection (MIP) and shaded surface display as a technique for generating three-dimensional (3D) images of the vasculature from spiral computed tomography (CT) data sets. In four patients with pathologic splanchnic vasculature, the advantages of volume-rendered display are illustrated for depiction of 3D vascular anatomy, vascular and visceral interrelationships, variant vasculature, tumor encasement, and hepatic tumor localization for presurgical planning.

Abdomen↗
PubMed1996

Automatic liver segmentation technique for three-dimensional visualization of CT data.

PURPOSE: To develop a system for automatic segmentation of the liver from computed tomographic (CT) scans of the abdomen for three-dimensional volume-rendering displays. MATERIALS AND METHODS: An automated liver segmentation system was developed, which combined domain knowledge with analysis of a global histogram, morphologic operators, and the parametrically deformable contour model. Boundaries of the thresholded liver volume were modified section-by-section by exploiting information from adjacent sections. These boundaries were refined by optimization of the parametrically deformable contour model. Volume-rendered images were created by using the boundaries to exclude tissues outside the liver. The system was tested on CT data sets from 10 cases of potentially resectable hepatic neoplasm. RESULTS: Of the 401 sections in the 10 cases, 53 sections (13.2%) required user modifications during segmentation. The utility of the three-dimensional-rendered images with use of these liver boundaries was judged by a radiologist as being comparable to that of three-dimensional images created with manual editing. Twenty-eight of the sections were deemed imperfect by the radiologist and might need further modifications. CONCLUSION: An effective technique for automatic segmentation of the liver from CT images has been developed. This technique promises to save time and simplify the creation of three-dimensional liver images by minimizing operator intervention.

Humans↗
PubMed1996

Portal-phase contrast-enhanced helical CT for the detection of malignant hepatic tumors: sensitivity based on comparison with intraoperative and pathologic findings.

OBJECTIVE: The purpose of this study was to determine the sensitivity of portal-phase IV contrast-enhanced helical CT in detecting malignant hepatic tumors using a lesion-by-lesion comparison with surgical and pathologic findings. MATERIALS AND METHODS: Preoperative portal-phase contrast-enhanced helical CT studies in 21 patients (13 men, eight women) with malignant neoplasms of the liver (12 patients with primary hepatic tumors, nine patients with metastases) were reviewed retrospectively by three radiologists with the knowledge that hepatic malignancies were present in each case. Helical CT findings were compared with intraoperative findings by palpation (21 patients), sonography (15 patients), and the results of pathologic examination of resected specimens (10 patients) in a lesion-by-lesion manner. Sixty-four malignant nodules were identified in resected specimens or at surgery by palpation or intraoperative sonography. For each nodule identified by surgical or pathologic means, CT findings were reviewed for the presence of a lesion of similar size and location. RESULTS: The readers identified 52 of 64 nodules on helical CT scans for an overall sensitivity of 81%. Sixteen of 21 primary tumors (76%) and 36 of 43 metastatic tumors (84%) were identified on CT scans. The sensitivity was 91% for nodules greater than 1 cm (42 of 46) and 56% for nodules 1 cm or less (10 of 18). False-positive findings occurred in 4% of lesions seen on helical CT scans. CONCLUSION: Our results show that portal-phase contrast-enhanced helical CT is extremely sensitive (91%) for detecting malignant hepatic tumors greater than 1 cm, is relatively insensitive (56%) for tumors less than 1 cm, and has a low false-positive rate. These results compare favorably with published results for CT during arterial portography, the current gold standard for liver tumor detection, suggesting that portal-phase IV contrast-enhanced helical CT is an excellent noninvasive preoperative study prior to hepatic resection or cryosurgery.

Adult↗
PubMed1996

Hepatic tumors treated by cryosurgery: normal CT appearance.

OBJECTIVE: An understanding of the normal appearance of hepatic tumors treated with cryosurgery is essential for accurately distinguishing normal postoperative changes from potential complications such as hepatic abscess or infarct, which may necessitate further interventions. The purpose of this study was to characterize the normal spectrum of CT findings after cryoablation of hepatic tumors. SUBJECTS AND METHODS: The CT scans of 14 patients who had undergone hepatic cryoablation 4-16 days (mean, 7 days) before scanning were reviewed by three radiologists. None of these patients had postprocedural complications that necessitated intervention (e.g. abscess, infarct, or hemorrhage). Indications for cryoablation included primary hepatic tumors in four patients and hepatic metastases in 10 patients. CT findings were correlated with surgical findings in a lesion-by-lesion manner to ensure that only cryolesions were included in the analysis. RESULTS: Twenty-eight cryolesions from 3 to 11 cm maximum diameter (mean, 7 cm) were detected on CT scans. All cryolesions were primarily hypodense and extended to the liver capsule. Ten (36%) of 28 lesions contained air, and 26 (93%) of 28 lesions contained hemorrhage. Thirteen (54%) of 24 lesions evaluated with i.v. contrast material showed peripheral enhancement. Cryolesions were primarily wedge shaped (54%), round (29%), or teardrop shaped (21%). One iatrogenic portosystemic shunt was detected. Other associated findings included subcapsular hemorrhage (29%), perihepatic fluid collections (43%), right-sided pleural effusion (93%), left-sided pleural effusion (64%), atelectasis of one or both lungs (93%), and ascites (7%). CONCLUSION: The postoperative CT appearance of the liver in patients who underwent hepatic cryoablation without complications mimics that seen in the liver of patients with hepatic abscesses or infarcts. The CT appearance of the liver in patients undergoing cryosurgery needs to be carefully analyzed to avoid confusing normal findings related to the procedure with those related to procedural complications, it may be impossible to differentiate hepatic complications from normal postoperative changes on the basis of CT findings in many of these patients.

Cryosurgery↗
PubMed1995

The current state of the art in three dimensional oncologic imaging: an overview.

PURPOSE: To provide an overview of the methods and clinical applications of three dimensional (3D) medical imaging in the oncologic patient. METHODS AND MATERIALS: We briefly outline the techniques currently used to create 3D medical images with an emphasis on their strengths and shortcomings as they relate to oncologic imaging and radiation therapy planning. We then discuss some of the most important and promising oncologic applications of 3D imaging and suggest likely future directions in this rapidly developing field. RESULTS: Since the first application of 3D techniques to medical data over a decade ago, 3D medical images have evolved from relatively crude representations of musculoskeletal abnormalities to detailed and accurate representations of a variety of soft tissue, vascular, and oncologic pathology. The rapid development of both computer hardware and software coupled with the application of 3D techniques to a variety of imaging modalities have expanded the clinical applications of this technology dramatically. CONCLUSIONS: 3D medical images are clinically practical tools for oncologic evaluation and effective radiation therapy planning.

Humans↗
PubMed1995

Three-dimensional spiral CT during arterial portography: comparison of three rendering techniques.

The three most common techniques for three-dimensional reconstruction are surface rendering, maximum-intensity projection (MIP), and volume rendering. Surface-rendering algorithms model objects as collections of geometric primitives that are displayed with surface shading. The MIP algorithm renders an image by selecting the voxel with the maximum intensity signal along a line extended from the viewer's eye through the data volume. Volume-rendering algorithms sum the weighted contributions of all voxels along the line. Each technique has advantages and shortcomings that must be considered during selection of one for a specific clinical problem and during interpretation of the resulting images. With surface rendering, sharp-edged, clear three-dimensional reconstruction can be completed on modest computer systems; however, overlapping structures cannot be visualized and artifacts are a problem. MIP is computationally a fast technique, but it does not allow depiction of overlapping structures, and its images are three-dimensionally ambiguous unless depth cues are provided. Both surface rendering and MIP use less than 10% of the image data. In contrast, volume rendering uses nearly all of the data, allows demonstration of overlapping structures, and engenders few artifacts, but it requires substantially more computer power than the other techniques.

Algorithms↗
PubMedDate not supplied

Subcutaneously tethered temporary filter: pathologic effects in swine.

PURPOSE: To evaluate the histopathologic effects of the Tempo-filter, a temporary caval filter, on the caval wall and determine the feasibility of deployment and removal of the device in swine. MATERIALS AND METHODS: Filters were placed in the infrarenal inferior vena cava of 11 swine. The tethering catheter was sutured in a subcutaneous pocket near the puncture site. The original tethering catheter used in humans and a stiffer catheter designed to prevent migration in swine were evaluated. Postplacement, mid-study, and preexplant vena cavography procedures were performed. Four swine underwent in situ dissection at 3-10 weeks. Filters were removed from seven animals just before they were killed at 1-6 weeks. RESULTS: All filters were successfully placed. All seven filters were successfully removed at up to 6 weeks after placement. Cephalic migration of more than 1 cm was observed in 10 of 11 swine (100% of original catheters, 83% of stiff catheters). Other complications were more common with stiffer tethering catheters, including caval stenosis in 40% of original catheters and 100% of stiff catheters, filter cone thrombus in 0% and 67%, tethering catheter thrombus in 20% and 83%, pulmonary embolism in 0% and 50%, and death in 0% and 17%, respectively. There was mild vessel wall damage in the vena cava. CONCLUSION: Placement of the Tempofilter and removal at up to 6 weeks after placement is feasible.

Animals↗
PubMedDate not supplied

Dural ectasia in the Marfan syndrome: MR and CT findings and criteria.

PURPOSE: To create criteria for detecting dural ectasia on MR or CT images in adult Marfan patients. METHODS: Images were analyzed using a workstation. Parameters that predicted dural ectasia were included in our criteria. RESULTS: Major criteria include: (1) width of dural sac below L5 > width above L4; (2) anterior sacral meningocele. Minor criteria include: (1) L5 nerve root sleeve diameter > 6.5 mm and (2) S1 scalloping > 3.5. Dural ectasia exists if 1 major or 2 minor criteria are present. CONCLUSION: MR and CT diagnose dural ectasia with high specificity and sensitivity. Our criteria accurately diagnose dural ectasia in adult Marfan patients.

Adult↗
PubMedDate not supplied

Three-dimensional volume rendering of spiral CT data: theory and method.

Three-dimensional (3D) medical images of computed tomographic (CT) data sets can be generated with a variety of computer algorithms. The three most commonly used techniques are shaded surface display, maximum intensity projection, and, more recently, 3D volume rendering. Implementation of 3D volume rendering involves volume data management, which relates to operations including acquisition, resampling, and editing of the data set; rendering parameters including window width and level, opacity, brightness, and percentage classification; and image display, which comprises techniques such as "fly-through" and "fly-around," multiple-view display, obscured structure and shading depth cues, and kinetic and stereo depth cues. An understanding of both the theory and method of 3D volume rendering is essential for accurate evaluation of the resulting images. Three-dimensional volume rendering is useful in a wide variety of applications but is just now being incorporated into commercially available software packages for medical imaging. Although further research is needed to determine the efficacy of 3D volume rendering in clinical applications, with wider availability and improved cost-to-performance ratios in computing, 3D volume rendering is likely to enjoy widespread acceptance in the medical community.

Algorithms↗
PubMedDate not supplied

Neurofibromatosis type 1: a diagnostic mimicker at CT.

Neurofibromatosis type 1 (NF1) is the most common of the phakomatoses and has a variety of localized or, more frequently, systemic manifestations throughout the thorax, abdomen, pelvis, and extremities. Classic computed tomographic (CT) findings in NF1 with thoracic involvement include small, well-defined subcutaneous neurofibromas, focal thoracic scoliosis, posterior vertebral scalloping, enlarged neural foramina, and characteristic rib abnormalities due to bone dysplasia or erosion from adjacent neurofibromas. However, more atypical manifestations are occasionally seen, and magnetic resonance (MR) imaging can be useful in equivocal cases. NF1 with abdominopelvic involvement tends to arise in the retroperitoneal, mesenteric, and paraspinal regions; it may be quite extensive and therefore difficult to distinguish from adenopathy at CT. The multiplanar capabilities of MR imaging, particularly with T2 weighting, make this modality helpful in evaluating affected patients and making the diagnosis. The classic peripheral manifestations of NF1 include limb hemihypertrophy, pseudarthrosis, peripheral nerve neurofibromas, and subcutaneous common and plexiform neurofibromas. In some cases of NF1, imaging findings are inconclusive, and biopsy and subsequent pathologic analysis are required. Familiarity with the various manifestations of NF1 in different anatomic locations is important in making the diagnosis and optimizing postdiagnostic treatment.

Diagnosis, Differential↗