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In 102 patients suspected of pulmonary embolism, we have assessed the ability of a radionuclide (emission) venogram to complement the pulmonary perfusion scintigram in establishing a diagnosis. The efficacy was compared using decision analysis and Bayes's theorem. Two criteria for a positive test were compared: Criterion 1--the test is positive if the lung scan a) indicates a high probability of pulmonary embolus, or b) is abnormal but indeterminate for pulmonary embolus; Criterion 2--the test is positive a) if the lung scan indicates a high probability of pulmonary embolus, or b) if the emission venogram is positive in a patient with a lung scan considered abnormal but indeterminate for pulmonary embolus. The use of Criterion 2 decreased the sensitivity from 100% to 95% and increased the specificity from 74% to 93%. We conclude that a simultaneous emission venogram assists in improving the specificity, accuracy, and the predictive value of a standard pulmonary perfusion study in the diagnosis of pulmonary embolus.

This study presents the results of comparison of hepatic fat content with hepatic xenon retention in 45 patients. The degree of hepatic Xe-133 retention was measured during pulmonary ventilation studies. The amount of hepatic steatosis was graded 0 to 4+ on histologic liver sections obtained by needle or surgical biopsy. There was agreement between the amount of hepatic xenon retention determined scintigraphically and the degree of steatosis determined histologically. These results suggest that Xe-133 retention in the liver provides a simple means of evaluating fatty infiltration of the liver. The potential of this technique as a noninvasive means of investigating hepatic fatty infiltration is discussed.

Hepatic focal defects identified with 99mTc-sulfur colloid imaging procedures are nonspecific. This report describes a case of an ectopic gallbladder localized by cholecystography and 131I-rose bengal studies in a patient with cirrhosis and suspected intrahepatic neoplasm.

The diagnostic accuracy, ease, and technical feasibility of imaging with 131I-or 125 I-fibrinogen, 99mTc-sulfur colloid, and 67 Ga-citrate in renal transplant rejection are compared. Radiofibrinogen data resulted from literature review, radiocolloid data from 125 studies in 52 transplant patients, and gallium citrate data from 24 examinations in seven renal transplant patients performed simultaneously with the radiocolloid studied. Specificity of graft labeling during rejection appears to be similar with radiofibrinogen, 99mTc-sulfur colloid, and 67Ga-citrate. For routine clinical use 99mTc-sulfur colloid surpasses radiofibrinogen and radiogallium because of its better imaging qualities with a permissible radiation dose, leading to better separation of positive and negative results. The 99mTc-sulfur colloid accumulates in areas of intravascular fibrin thrombosis in acute and chronic rejecting renal transplants. Hence, the mechanisms for accumulation of 99mTc-sulfur colloid and labeled fibrinogen in rejecting transplants would seem to be similar. Such physiologic properties as rapid blood clearance and such physical properties as short physical half-life combine to produce reliable graft visualization with adequate definition, thus favoring 99mTc-sulfur colloid as the single agent of choice for clinical evaluation of renal transplant rejection at this time.

Local radioactive areas in the liver were observed as a result of superficial cavoportal shunting of radiocolloids in two patients with the inferior vena cava syndrome. In one patient a paraumbilical and/or a recanalized umbilical vein was apparently involved in the hepatopetal shunting. In the other patient a superficial anastomosis other than the paraumbilical vein shunted colloid to the liver. Relatively discrete areas of increased radioactivity, single or multiple, were seen in the left lobe. Virtually all reported instances of hepatopetal shunting of radioparticles in a superior or an inferior vena cava syndrome have demonstrated similar findings. Various hepatopetal collateral pathways in infrarenal caval obstruction are considered, and factors that could affect liver scan findings in the infrarenal obstruction are discussed.