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Biomedical subjects

E K Fishman

Publications and source records attributed to E K Fishman.

At least 91 records · Page 5Linked to original sources
PubMed1999

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↗
PubMed1999

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↗
PubMed1999

Postpartum complications in the abdomen and pelvis: CT evaluation.

Postpartum patients rarely develop complications that require radiologic evaluation. When indicated, CT can provide a rapid and reliable examination of the major pelvic organs and enable diagnosis of a multitude of postpartum complications, including abscesses, endometritis, thrombophlebitis, as well as more serious and potentially life-threatening sequelae of toxemia, DIC, and HELLP syndrome. This pictorial essay illustrates the utility of CT in the postpartum patient and demonstrates the spectrum of complications evaluated with CT.

Abdomen↗
PubMed1998

DNA content and other factors associated with ten-year survival after resection of pancreatic carcinoma.

BACKGROUND AND OBJECTIVES: The 5-year survival rates after resection of pancreatic carcinoma have recently increased and are predicted by tumor size, DNA content, and lymph node metastases at the time of resection. However, whether the 10-year survival rates have also increased and are similarly predicted by these factors is not known. METHODS: The influence of preoperative imaging tests, alcohol consumption, cigarette smoking, K-ras mutations, anatomic location, details of surgical resection, pathologic findings, and tumor DNA content on survival was tested for 96 patients after a successful resection of a pancreatic carcinoma with 17 patients being followed for more than 5 years. RESULTS: The 5- and 10-year patient survival rates were 18% and 3%, respectively. Univariate and multivariable analyses showed that tumor DNA content, pathologic tumor size, and lymph node metastases were the strongest prognostic indicators for long-term patient survival, although the importance of tumor size may diminish 2 or more years after resection. Surprisingly, the 11 patients with diploid carcinomas > or = 4 cm had an estimated 10-year survival rate of 36%. CONCLUSION: These results show that the 10-year survival rate for pancreatic carcinoma remains very low, although the subset of patients with biologically favorable tumors has a prolonged survival and possible cure after resection.

Adenocarcinoma↗
PubMed1998

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↗
PubMed1998

Granulocytic sarcoma (chloroma) of the sacrum: initial manifestation of leukemia.

We present an unusual case of a granulocytic sarcoma (chloroma) of the sacrum which predated the initial clinical manifestation of acute myelogenous leukemia. Although granulocytic sarcomas occur in up to 9.1% of cases of acute myelogenous leukemia they usually present concurrently with the leukemic presentation. Although granulocytic sarcomas can involve several different organ systems, bone is the most common site.

Female↗
PubMed1998

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↗
PubMed1998

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↗
PubMed1998

Three-dimensional CT angiography: renal applications.

CT angiography has become an effective noninvasive imaging modality for evaluating the renal vasculature. The current clinical applications for CT angiography and three-dimensional (3D) imaging related to the kidneys and renal vasculature include evaluation of renal artery stenosis, renal diseases related to aortic diseases, living-related renal donor candidates, and preoperative evaluation of renal masses for possible nephron sparing surgeries. Imaging parameters need to be individually prescribed for renal CT angiography depending on the diagnostic goal of the examination. Methods for optimizing spiral CT protocols including patient preparation, contrast administration, image acquisition parameters, and image reconstruction will be covered.

Angiography↗
PubMed1998

Three-dimensional CT angiography of the thorax: clinical applications.

Spiral CT with three-dimensional (3D) display can provide a rapid noninvasive examination of the vascular system and has been shown to have a wide range of clinical applications in the thorax, including imaging of the aorta, pulmonary vasculature, and venous abnormalities. Three-dimensional images can provide views of the imaging volume from innumerable viewing angles for both the radiologist and referring clinician, and potentially obviate invasive procedures such as angiography. In this article, we will review many of these applications of spiral CT angiography with 3D displays. Emphasis is placed on study design, protocol selection, and display of pathology.

Angiography↗
PubMed1998

Radiologic evaluation of the acute abdomen in the patient with acquired immunodeficiency syndrome (AIDS): the role of CT scanning.

Abdominal complaints are common in the HIV-infected patient, and the signs and symptoms of disease may be masked by concurrent illness and a weak immune response, making accurate diagnosis difficult. Patients with acquired immunodeficiency syndrome (AIDS) are susceptible to diseases common to the general population; however, their generalized state of immunodeficiency places them at increased risk for many unusual disorders, predominately infectious and neoplastic. Radiologic evaluation, in particular, computed tomography (CT) with its ability to image the entire abdomen and pelvis, plays a crucial role in the prompt and accurate diagnosis and treatment of these patients.

AIDS-Related Opportunistic Infections↗
PubMed1998

Musculoskeletal complications of the patient with acquired immunodeficiency syndrome (AIDS): CT evaluation.

Musculoskeletal disorders are infrequent complications of HIV infection in this country. However, AIDS patients are susceptible to a wide range of musculoskeletal complications, from the common to the otherwise uncommon. The following is a summary of some of the more frequently encountered musculoskeletal manifestations of these disorders within the HIV-positive community and their associated imaging characteristics.

Acquired Immunodeficiency Syndrome↗
PubMed1998

Abdominal image segmentation using three-dimensional deformable models.

RATIONALE AND OBJECTIVES: The authors develop a three-dimensional (3-D) deformable surface model-based segmentation scheme for abdominal computed tomography (CT) image segmentation. METHODS: A parameterized 3-D surface model was developed to represent the human abdominal organs. An energy function defined on the direction of the image gradient and the surface normal of the deformable model was introduced to measure the match between the model and image data. A conjugate gradient algorithm was adapted to the minimization of the energy function. RESULTS: Test results for synthetic images showed that the incorporation of surface directional information improved the results over those using only the magnitude of the image gradient. The algorithm was tested on 21 CT datasets. Of the 21 cases tested, 11 were evaluated visually by a radiologist and the results were judged to be without noticeable error. The other 10 were evaluated over a distance function. The average distance was less than 1 voxel. CONCLUSIONS: The deformable model-based segmentation scheme produces robust and acceptable outputs on abdominal CT images.

Algorithms↗
PubMed1998

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↗