Comparative study of radioactive chlormerodrin (Neohydrin) tagged with mercury 197 and mercury 203 for brain scanning

Abstract

In patients with verified intracranial lesions, double isotopic scans were carried out using chlormerodrin tagged with Hg203 and Hg197. The percentage differential uptakes of the lesions were about the same magnitudefor various types of intracranial neoplasms. The optimal dosage of chlormerodrin with Hg197 was found to be 5 [mu]c. per kilogram of body weight or half of the dosage for chlormerodrin tagged with Hg203. The radiation dose to the kidneys with chlormerodrin plus Hg197 is less than 3% (1 rad) of that from chlormerodrin plus Hg197 (40 rads). A correlation of positive scans with the presence of verified intracranial lesions was 84 to 90% with the use of either scanning agent. In this series, we found that reverse or negative scans usually can be attributed to limitation of the instrumentation in regard to midline or small lesions (less than 1 cm. in diameter) and to the poor concentration of chlormerodrin by low-grade gliomas. These comparative studies show that chlormerodrin plus Hg197 gives scans as satisfactory as those from chlormerodrin plus Hg203. At the same time, the radiation dosage to the kidney is reduced to a negligible level.