The use of a thrombus-specific ultrasound contrast agent to detect thrombus in arteriovenous fistulae.

RATIONALE AND OBJECTIVES: To evaluate the use of a new thrombus-specific ultrasound contrast agent, MRX-408, in the ultrasonic detection of thrombus in arteriovenous (AV) fistulae. METHODS: Six purpose-bred mongrels with two AV fistulae each were imaged with gray-scale ultrasound 7 weeks after graft implantation before and after the intravenous bolus injection of MRX-408 (a GPIIb receptor-targeted ultrasound contrast agent). Pre- and postcontrast videotaped segments were randomized and reviewed by four radiologists blinded to the presence of thrombus in the grafts. RESULTS: After the use of MRX-408, there was improved visualization of thrombus within the grafts (P < 0.0001). This was due to the enhancement of the thrombus (P < 0.0001). The improved visualization and contrast enhancement were more marked in the grafts that contained thrombus nonhyperechoic to surrounding soft tissues. CONCLUSIONS: MRX-408 demonstrated better visualization of thrombus within AV fistulae. This was shown in both patent and occluded grafts. These results are encouraging and suggest that this contrast agent merits further development.

Gastrointestinal complications of chronic granulomatous disease: case report and literature review.

Chronic granulomatous disease (CGD), an inherited disorder of phagocytic leukocyte function, is characterized by recurrent infections with catalase-positive organisms. Gastrointestinal (GI) tract involvement, present in the majority of affected individuals, may be present initially and recurrently, mimics other entities such as inflammatory bowel disease, and causes substantive morbidity and mortality. Disorders of motility, ulceration, obstruction, and infection (e.g., abscesses) occur from the mouth to the anus and stereotypically manifest with vomiting, diarrhea, abdominal pain, weight loss, and fever. Careful physical examination, in concert with appropriate diagnostic studies, is necessary to delineate intraabdominal pathologic processes. Abdominal radiographs, ultrasonography, computerized tomography, and endoscopy are useful ancillary diagnostic procedures. Drainage of accessible abscesses, antimicrobial therapy based on organisms cultured from blood and tissue, and interferon gamma may lead to suppression or eradication of infections and resolution of symptoms. Corticosteroids are useful for gastric outlet obstruction and sulfasalazine and cyclosporine for large bowel disease. Gallbladder dysfunction may be ameliorated, as in our patient, with administration of cholestyramine.

Reduction of patient exposure in pediatric radiology.

RATIONALE AND OBJECTIVES: The authors determined whether presently used exposure levels in pediatric imaging can be reduced without loss of information or a decrease in diagnostic accuracy. MATERIALS AND METHODS: Multiple (stacked) image detectors and filters were used to obtain identical compute radiographic images at different exposure levels of neonates with either no active lung disease or hyaline membrane disease. Physical characteristics of the images were measured. A contrast-detail study and a receiver operating characteristic study were conducted to measure observer performance. RESULTS: Physical measurements and results of the contrast-detail study revealed that the dose-reduction images were essentially limited by x-ray quantum noise. Results of the receiver operating characteristic study indicated that diagnostic accuracy did not decrease significantly up to about 75% exposure reduction levels, although image quality rating data decreased with each exposure reduction. CONCLUSION: Decreasing exposure levels to about 75% of current levels may be acceptable in some clinical situations where dose is a concern, such as in pediatric imaging.

Evaluation of electrofulguration in control of bleeding of experimental gastric ulcers.

The safety and efficacy of electrofulguration for control of bleeding from standard canine experimental gastric ulcers was studied. At settings of 2, 5, and 8 on a Valleylab SSE-3 generator, 0.5-sec applications provided effective hemostasis. However, a setting of 2 required an excessive number of applications. Settings of 5 and 8 showed deep injury to the muscularis externa when examined histologically. In an attempt to reduce the depth of injury, a more easily ionizable gas mixture of 50% argon gas and 50% CO2 was compared to CO2 alone. At a generator setting of 5 with 0.5-sec applications the argon-CO2 mixture produced slightly less deep injury than CO2 alone, but the difference was not significant. Although electrofulguration was effective in stopping bleeding in these experiments, the tissue injury was unpredictable and deep.