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A technique for analysis of dynamic radionuclide studies of the cerebral circulation is described. This technique permits objective classification of observed radionuclide distribution patterns. Variation in the time-to-peak activity, and in the maximum attained activity as determined by region-of-interest analysis of cerebral hemispheric activity, was defined for a normal population. Application of these normal values permits classification of observed hemispheric radionuclide distribution patterns in anaplastic gliomas and in occlusive cerebrovascular disease. Radionuclide activity in gliomas may be normal, decreased, or increased in the region of the tumor. In cerebrovascular occlusion, decreased activity, associated with a delay in time-to-peak activity, is frequently demonstrated in the affected hemisphere.

The results of seven laboratory tests of liver function, including spleen/liver activity ratios obtained by densitometric analysis of scans, are analyzed in 50 patients with proven Laennec's cirrhosis. In this series, the liver scan not only disclosed the liver gross anatomy and structural abnormality and established the best possible site for biopsy examination, but also, the increased splenic activity served as a useful diagnostic indication of Laennec's cirrhosis. Of 50 proven cases of Laennec's cirrhosis, 41 (82%) had abnormal spleen/liver ratios. An abnormal spleen/liver ratio in combination with abnormal results from any one or two other tests was relatively effective in the detection of cirrhosis. The accuracy is improved if the other laboratory tests are chosen from among tests for serum albumin, serum bilirubin, and SGOT. (Liver abnormalities other than cirrhosis can also present an abnormal spleen/liver ratio.) This simple determination extends the value of the liver scan commonly requested in search of metastases, primary lesions, or inflammatory processes, or in preparation for needle biopsy examination.

Serial 99mTc pyrophosphate scintigrams were obtained 7 hr to 15 days after experimental acute myocardial infarction produced by permanent or transient coronary occlusion. Scintigrams were interpreted visually and the increased radioactivity in the precordial image was quantitated and compared to extent of infarction found histologically. Results of these studies indicate: 1) 99mTc pyrophosphate imaging is an extremely sensitive for detection of acute myocardial infarction, i.e., infarction in excess of 1% of the left ventricular mass was detected. 2) Early detection of acute infarction is a function of blood flow since 7 hr after infarction scans were negative after permanent occlusion but were strongly positive after transient occlusion. 3) Radioactivity in the precordial image was inversely related to extent of infarction after permanent occlusion and directly related to extent of infarction after transient occlusion. 4) 99mTc pyrophosphate localized in areas with significant histologic infarction but the distribution of radioactivity was not proportional to extent of infarction.

Relative spleen/liver activity ratio was determined from posterior projection images using a photodensitometric method. Ratios from scans of 22 patients with proven pancreatic carcinoma (12 from rectilinear scans and 10 from scintillation camera images) were determined and compared to studies from patients documented as normal and to randomly selected liver/spleen imaging studies which had been previously interpreted as normal. The mean ratio from the pancreatic carcinoma group was significantly lower than the means of the respective normal groups (p[t] less than .0001 for rectilinear scans and p[t] less than .001 for scintigrams). There was no significant difference between the means of the proven normal and randomly selected normal groups or between the two pancreatic carcinoma groups. Splenic vascular alteration is discussed as a possible reason for decreased splenic distribution of Tc-99m-sulfur colloid in this patient group.