Comparison of CVA imaging with 99mTc phosphates, 99mTc pertechnetate, and computed tomography

A retrospective study was made of 111 patients who underwent computed tomography (CT) and nuclear brain scans, with both pertechnetate and phosphate bone agents (PHOS), within 7 days of each other. Specifically, 78 patients who had a recent cerebral vascular accident (CVA) were compared. There were no significant sensitivity differences between the methods. While these studies appear complementary, the most important criterion is the time after onset when the studies were performed. The axiom "if the intensity of the phosphate scan exceeds that of the pertechnetate, the lesion must be a CVA" is true, only if the study is performed within 4 weeks of onset. The most economical method for optimum detection of CVA, with avoidance of frequent errors, is an early CT followed by a PHOS brain scan about 14 days after ictus in those that have initial negative CT.