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Biomedical subjects

G D Schweiger

Publications and source records attributed to G D Schweiger.

14 recordsLinked to original sources
PubMed2001

Management of suppurative pylephlebitis by percutaneous drainage: placing a drainage catheter into the portal vein.

Persistent infection of the portal vein is a rare entity with significant mortality. We present two cases of infected thombis of the portal vein, one infected with fungus and the other with bacteria, both requiring percutaneous drainage to allow a response to antibiotics. The distinction between bland thrombis, infected thrombis, portal venous air, and pneumobilia will be discussed so that suppurative pylephlebitis can be recognized more easily as drain placement appears to affect a more prompt degree of improvement than antibiotics alone.

Candidiasis↗
PubMed1998

Teaching physical examination of the adult liver with use of real-time sonography.

RATIONALE AND OBJECTIVES: The authors developed and evaluated an approach to teaching examination of the liver that incorporates real-time ultrasound (US) imaging as immediate feedback to improve diagnostic accuracy. MATERIALS AND METHODS: Second-year medical students participating in a course in physical examination were assigned to receive instruction in measuring liver span without (group 1) or with (group 2) real-time sonography. Students from each group attended a practice session given by one of two physicians who were board certified in radiology and internal medicine with special expertise in US. During the practice session for group 2, students were shown the boundaries of the liver of the practice patient with real-time US. Both groups of students then made three measurements each of the liver span of a healthy practice patient and a single healthy test patient without US. The vertical liver span reference standard was determined by one of the authors. RESULTS: Students in group 2 showed greater accuracy in measuring liver span during both the practice and the test sessions than did students in group 1. The differences were significant for the third practice measurement and all three test measurements (P < .05). CONCLUSION: The use of real-time US as an aid in teaching physical examination improves students' accuracy in measuring liver size.

Adult↗
PubMed1998

Optimizing contrast enhancement during helical CT of the liver: a comparison of two bolus tracking techniques.

OBJECTIVE: The purpose of this study was to evaluate a recently developed hardware and software system for CT scanning that generates images in real time and switches to helical CT scanning by either a visual cue or a region of interest (ROI) amplitude threshold. SUBJECTS AND METHODS: We randomly and prospectively divided 120 abdominal CT examinations into three groups. Two groups received 75 ml of contrast agent at 1.5 ml/sec. Helical CT scanning began after visualization of the contrast bolus arrival in the hepatic veins (visual cue triggering) (39 patients) or after reaching an ROI threshold (automated ROI threshold triggering) (39 patients). A third group served as a control group (42 patients) and received 150 ml of contrast agent at 1 ml/sec. Quality of hepatic enhancement was assessed objectively and subjectively. Comparisons were made after stratifying each group into three weight classes. RESULTS: Errors occurred in 12 (31%) of 39 examinations in the group with automated ROI threshold triggering. In that group, we found a significantly (p < .04) lower mean hepatic enhancement in two of three weight categories, and a significantly (p < .04) lower mean subjective scan quality in one of three weight categories, than we found in the group with visual cue triggering. CONCLUSION: Optimizing portal venous phase helical CT of the liver after a low-volume bolus of contrast agent and an injection rate of 1.5 ml/sec is best achieved by initiating helical CT scanning after visualizing the contrast bolus arrival within the liver rather than after reaching a preset attenuation threshold.

Adult↗
PubMed1997

Accuracy of color Doppler sonography in assessing venous thrombus extension in renal cell carcinoma.

OBJECTIVE: Our objective was to evaluate the accuracy of color Doppler sonography for assessing tumor thrombus extension into the renal veins, the inferior vena cava, and the right side of the heart in patients with renal cell carcinoma. MATERIALS AND METHODS: Over the past 4.5 years, 44 patients with 46 renal cell carcinomas were examined with color Doppler sonography for the presence and extent of tumor thrombus in the renal veins, the inferior vena cava, and the right side of the heart. Examinations were performed after an equivocal CT scan in 34 patients and as a primary imaging technique in 10. Color Doppler sonographic findings were correlated with surgical-pathologic findings or findings from autopsies performed within 3 months of the Doppler study. Seven patients were excluded: two because of poor technical quality caused by body habitus and five because pathologic correlation was performed more than 3 months after the color Doppler sonographic examination. The remaining 39 renal vein and 37 caval Doppler examinations constituted the study material. Criteria used for the diagnosis of tumor thrombus included distention of the renal vein or the inferior vena cava by echogenic material and partial or complete absence of flow detected with color Doppler sonographic examination. RESULTS: Sixteen of 39 renal veins evaluated had pathology-proven tumor thrombus. Color Doppler sonography was 87% accurate with a sensitivity of 75%, a specificity of 96%, a positive predictive value of 92%, and a negative predictive value of 85%. In two false-positive cases, involvement was limited to intrarenal veins, causing no change in the surgical approach. Five of 37 inferior venae cavae evaluated had proven involvement by tumor thrombus. Color Doppler sonography was 100% accurate in assessing the presence and extent of inferior vena caval involvement by tumor thrombus. Extension into the right atrium and ventricle that was shown by this technique was proven by surgery in one case. The overall accuracy for detecting venous involvement for both the renal veins and the inferior vena cava was 93%, the sensitivity was 81%, and the specificity was 98%. CONCLUSION: In patients with renal cell carcinoma, color Doppler sonography appears to be fairly accurate in assessing tumor extension into the renal veins, the inferior vena cava, and the right side of the heart. Although CT is the primary imaging technique for staging renal cell carcinoma, color Doppler sonography may be used as a complementary technique for assessing venous extension in patients with an equivocal CT examination.

Carcinoma, Renal Cell↗
PubMed1997

Pediatric radiology at a rural hospital: value of teleradiology and subspecialty consultation.

OBJECTIVE: We performed a field study and subsequent laboratory investigation of pediatric radiology at a small rural hospital. Our investigation had three components: to describe the characteristics of pediatric radiology in a rural primary care facility, to test the diagnostic accuracy of interpretation of pediatric images transmitted by teleradiology, and to compare relative diagnostic accuracy of general and pediatric radiologists who interpreted pediatric images at a rural institution. MATERIALS AND METHODS: All 196 pediatric radiographs obtained during a 4-month period comprised the database from which we determined practice characteristics. Reports of 153 unselected cases interpreted by general radiologists using teleradiology were compared with interpretation of the same cases by a pediatric radiologist who interpreted the original radiographs. Discrepant cases were further investigated by a receiver-operating-characteristic curve experiment in which general and pediatric radiologists interpreted each case twice: once viewing teleradiologic images and once viewing the original radiographs at another setting. We then compared interpretive accuracy of observers and techniques. RESULTS: The pediatric radiographs were predominantly simple examinations for common acute disease, particularly pneumonia and fractures. Discrepancies of interpretation between teleradiology and original radiographs, which occurred in 13% of images, showed no significant difference in accuracy of interpretation for either teleradiologic images or original radiographs. Likewise, we found no significant advantage for accuracy of interpretation by general or pediatric radiologists. Receiver-operating-characteristic analysis of 18 discrepant cases showed slightly increased accuracy for interpretation of original radiographs by pediatric subspecialists. CONCLUSION: Simple pediatric radiographs obtained at a rural primary care institution and transmitted by teleradiology can be adequately interpreted by general radiologists.

Adolescent↗
PubMed1994

Quantitative assay for the radiosensitivity of malignant melanomas.

There exists a controversy regarding the radiosensitivity of malignant melanomas. Several in vitro and in vivo studies have suggested that the 'radioresistance' of melanomas may be due to a 'large shoulder' on the cell survival curve. As yet, however, there is no consensus relating to the effects of total dose, the fraction size and the time between fractions. In this study, we have used a B16 mouse melanoma model to evoke a response with single doses of irradiation, and have attempted to evaluate the growth kinetics of in vivo irradiated and unirradiated tumour cells implanted in an unirradiated limb. The radiosensitivity of B16 melanoma cells was quantified by comparing the growth of tumour from an inoculum of 10(6) melanoma cells irradiated in vivo with various doses of radiation to the growth of tumour following inoculae of 10(3) to 10(7) cells derived from unirradiated melanoma. Using this bioassay we found that a single dose of 18 Gy leads to close to 99% of the surviving cells becoming nonclonogeneic. It is hoped that this assay will further the development of the most efficacious fractionation scheme in the treatment of malignant melanomas.

Animals↗
PubMedDate not supplied

CT fluoroscopic guidance for percutaneous needle placement into abdominopelvic lesions with difficult access routes.

BACKGROUND: We wished to evaluate the utility of computed tomography fluoroscopy (CTF) for guiding percutaneous abdominopelvic biopsies or fluid aspirations that are considered difficult with conventional computed tomographic (CT) guidance. METHODS: CTF-guided percutaneous biopsy (n = 11) or fluid aspiration (n = 2) was attempted in 13 patients with lesions that were otherwise difficult or potentially unsafe by conventional CT guidance because they were deep to colon, small intestine, or major blood vessels. RESULTS: Using CTF assistance to guide external compression or needle positioning, appropriate needle placement was performed in 11 patients. Biopsy or aspiration was diagnostic in 10 patients. Needle advancement was not attempted in two patients. CONCLUSION: CTF appears to be a valuable tool to dynamically assist percutaneous needle placement into lesions that may be considered difficult with standard CT assistance.

Abdomen↗
PubMedDate not supplied

Postbulbar duodenal ulceration and stenosis associated with celiac disease.

The case histories of five patients with celiac disease and postbulbar duodenal ulceration and stenosis are presented. Celiac disease was unexpected in three of the five patients until endoscopic biopsy revealed villous atrophy. Our findings suggest that duodenal ulceration and stenosis may be a more common complication of celiac disease than previously thought and may precede the clinical diagnosis of celiac disease or occur when there are minimal symptoms and nonspecific radiographic findings for the disease.

Adult↗
PubMedDate not supplied

Computed tomography fluoroscopy: techniques and applications.

Computed tomography fluoroscopy (CTF) was first introduced into clinical practice in Japan in 1993 and in the United States in 1995, yet it has been used predominantly at large academic hospitals. Early literature on CTF is composed primarily of abstracts that detail anecdotal experiences and that have been presented at major meetings. Scientific papers evaluating CTF in clinical practice have been introduced in scientific journals only recently. This article reviews the literature for CTF with specific emphasis on clinical techniques, applications, and results. It is the goal of the author to provide the reader with a basic working knowledge of how to perform CTF-guided procedures and how to integrate CTF into clinical practice.

Dose-Response Relationship, Radiation↗
PubMedDate not supplied

MR imaging of transarticular skip metastases from distal femoral osteosarcoma.

We describe a case in which magnetic resonance (MR) imaging of a distal femoral osteosarcoma showed transarticular skip metastases in the proximal tibia. These lesions were not found by conventional radiography, bone scintigraphy, or CT. Since detection of transarticular skip metastases has an important influence on surgical management, MR imaging of metaphyseal osteosarcomas should always include the bone on the opposite side of the joint.

Adult↗