Ken Hamamoto

Sequential brain imaging as an aid in understanding disease etiology

Sequential cerebral scintiphotography was performed with a gamma scintillation camera and intravenously administered 99m Tc pertechnetate. The results of the serial scans were correlated with the disease etiology as determined by angiography and surgery. Abnormal foci noted in sequential scinti-photographs revealed either a regressive or progressive course of radionuclide uptake. When the differential uptake was determined digitally, it was possible to classify chronologic patterns of nuclide accumulation into four groups. In Group 1, the uptake ratio reached the maximum value immediately or soon after administration of the tracer and then decreased rapidly. Vascular anomalies, angiomas and meningiomas belonged to this group; angiography and 133 Xe or 131 I-MAA scanning data all demonstrated high blood content and blood flow in the lesions. In Group 2, the uptake ratio showed a progressive increase with time. Gliomas of low grade malignancy, cerebral infarctions and abcesses showed this pattern. In Group 4, the uptake ratio did not exceed unity. This type of lesion was rare and was observed in large intracerebral hematomas and cysts. In Groups 2 and 4, the foci proved to be avascular at surgery or by other diagnostic methods. Group 3 included more or less vascular malignant tumors; namely glioblastomas, carcinomas or sarcomas. The uptake ratio showed an initial increase which was followed by a secondary decrease. In addition to the morphological characteristics of the brain scan such as the size, shape, margin, location, density, homogeneity and multiplicity of the radioactive foci, the dynamic analysis of time course of nuclide uptake appears to improve the diagnostic accuracy and provides useful information concerning the nature of the lesion.