Pelvic kidney displacing a sigmoid diverticular bleed. Scintigraphic and angiographic correlation.
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Biomedical subjects
Publications and source records attributed to L S Zuckier.
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Lymphocytic interstitial pneumonitis (LIP) is currently recognized as a frequent pediatric manifestation of the acquired immunodeficiency syndrome (AIDS). We report the gallium scan findings in a 3-yr-old girl with this disorder and review its clinical, radiologic, and pathologic features. LIP must be a prime consideration in the differential diagnosis of diffuse pulmonary gallium uptake in pediatric AIDS patients. Further experience will afford greater perspective on the diagnostic role that nuclear medicine will ultimately play in this disease.
Since the introduction of Tc-99m labeled radiopharmaceuticals, flow studies have become a useful and readily performed component of renal nuclear medicine examinations. In addition to detecting aberrations of renal perfusion, a number of extrarenal abnormalities may also be surreptitiously detected. Three cases of hyperperfused skeleton, an extremely unusual finding which complements two previous reports in the literature, have recently been observed. All three of the patients, as well as the two previously described, had underlying neoplastic abnormalities. The appearance of perfused skeleton should therefore be recognized as suggesting the presence of underlying neoplastic disease. Considerable interest as to the etiology and magnitude of the increased skeletal perfusion exists. Measurements of normal marrow and osseous perfusion have been reviewed in order to better appreciate the magnitude of increase required for skeletal visualization on renal flow studies. Some considerations as to the etiology of this increase are offered.
Several patients with renal failure in whom the kidneys were more clearly imaged with 99Tcm-DTPA than 131I-Hippuran were recently observed. We have postulated that our newer generation gamma-cameras have a reduced capacity to image 131I in comparison to older generation cameras. This hypothesis was tested by comparing representative older and newer imaging systems. Full-width tenth-maximum 99Tcm linespread functions were 1.20 and 1.55 cm for the older and newer cameras, respectively. The 99Tcm count rate on the newer camera was 111% that of the older camera, and the observed kidney to background count ratios in a phantom model were virtually identical for the two cameras imaging a number of simulated 99Tcm count distributions. Full-width tenth-maximum 131I linespreads were 1.55 and 4.78 cm, respectively, on the older and newer cameras and the 131I count rate on the newer camera was 27% of the count rate on the older system. The phantom model demonstrated a consistently lower 131I perceived kidney to background count ratio on the newer gamma-camera compared to the older system. These findings should be considered in the interpretation of 131I-Hippuran studies on newer-generation equipment until revised criteria of interpretation have been established. Non-visualization of the kidney may not have the same prognostic implication using modern cameras as has been reported from studies with older generation detector systems.
A 46-year-old man who had undergone apical cardiac aneurysmectomy with a ventriculotomy graft and implanted automatic cardioverter-defibrillator electrodes, presented with fever, left-sided pleuritic chest pain, and a draining sinus. A Ga-67 scan was performed to aid in determining whether the infection was limited to the chest wall or if it had penetrated deeper to the cardiac structures. Uptake of gallium within the cardiac region, in association with minimal rib uptake of Tc-99m MDP, strongly supported the existence of infection within the pericardium. CT scan demonstrated a pericardial collection which under CT-guided aspiration proved to be purulent. Definitive surgical drainage was performed, and the patient was discharged 4 weeks postoperatively. Ga-67 imaging can provide an accurate and relatively rapid means of localizing infection in the postcardiotomy patient. A thorough bibliography of pericardial gallium uptake is provided.
The Schilling examination remains a popular means of evaluating in vivo absorption of vitamin B12. When absorption is abnormally low, the test may be repeated with addition of exogenous intrinsic factor (IF) in order to correct the IF deficiency that characterizes pernicious anemia. A dual-isotope variation provides a means of performing both stages of the test simultaneously, thereby speeding up the test and reducing dependence on complete urine collection. The dual-tracer test depends on no exchange of B12 moieties on the IF molecule. In vitro studies suggest that this exchange does take place, in a manner dependent on time, temperature, and pH. Furthermore, in vivo studies indicate that, when administered simultaneously, the absorption of unbound B12 is elevated, and IF-bound B12 is reduced, in pernicious-anemia patients, relative to the classic two-stage examination. A number of clinical studies indicate significant difficulty in resolving clinical diagnoses with the dual-tracer test. The potential weaknesses of the test discussed herein can be overcome by temporally separating the administration of the two B12 doses and by treating secondary malabsorption where it exists. An algorithm is offered for selecting the most suitable variation of the Schilling test to improve the accuracy of test results and the ease of performance.
Several investigators have developed monoclonal antibodies against the capsular polysaccharide of Cryptococcus neoformans which have potential therapeutic applications. Using a rat model of C. neoformans meningitis, we studied the biodistribution and pharmacokinetics of a murine anticryptococcal capsular monoclonal antibody (mAb 2H1) after intravenous and intracisternal administration. After intravenous administration of 125I-labelled 2H1 to infected rats, there was no detectable localization of 125I in the brain or cerebrospinal fluid by either gamma-camera imaging of the whole animal or organ scintillation counting. In contrast, direct intracisternal instillation of 2H1 to infected rats resulted in persistent intracranial activity. In addition, the whole body half-life of intravenously administered radio labelled mAb 2H1 was significantly reduced in infected rats compared with uninfected rats. Our observations suggest that if high central nervous system (CNS) levels of mAb are needed to achieve a therapeutic effect in human C. neoformans meningoencephalitis, direct administration of mAb into the cerebrospinal fluid or modification of the mAb to increase penetration into the CNS may be required. Furthermore, higher or more frequent dosing of mAb may be required to maintain therapeutic levels in the presence of infection. This study demonstrates the usefulness of the rat as an experimental system for studying issues related to cryptococcosis.
Knowledge of the kinetics of cell distribution in vascular beds will help optimize engraftment of transplanted hepatocytes. To noninvasively localize transplanted cells in vivo, we developed conditions for labeling rat hepatocytes with 99mTc-pertechnetate. The incorporated o9mTc was bound to intracellular proteins and did not impair cell viability. When 99mTc hepatocytes were intrasplenically injected into normal rats, cells entered liver sinusoids with time-activity curves demonstrating instantaneous cell translocations. 99mTc activity in removed organs was in liver or spleen, and lungs showed little activity. However, when cells were intrasplenically transplanted into rats with portasystemic collaterals, 99mTc appeared in both liver sinusoids and pulmonary alveolar capillaries. To further localize cells, we transplanted DPPIV+ F344 rat hepatocytes into syngeneic DPPIV-recipients. Histochemical staining for DPPIV activity demonstrated engraftment of intrasplenically transplanted cells in liver parenchyma. In contrast, when 99mTc hepatocytes were injected into a peripheral vein, cells were entrapped in pulmonary capillaries but were subsequently broken down with redistribution of 99mTc activity elsewhere. Intact DPPIV+ hepatocytes were identified in lungs, whereas only cell fragments were present in liver, spleen, or kidneys. These findings indicate that although the pulmonary vascular bed offers advantages of easy accessibility and a relatively large capacity, significant early cell destruction is an important limitation.