The value of sequential scanning in the detection of metastatic tumors

The usefulness of sequential scanning, three and 24 hours after injection of 197Hg chlormerodrin in the detection of metastatic tumors of the brain has been demonstrated. The 24-hour scan was positive in 29% of the cases in which a metastatic lesion was suspected although the three-hour scan was negative, and the 24-hour scan also revealed additional masses in another 20%. The delayed scan helped to demarcate the actual location of the lesion in 24% of the cases in which the three-hour scan was graded merely suspicious. It is concluded that the addition of a 24-hour scan strongly reinforces the statistical accuracy of the 197Hg brain scan, and thus is of practical clinical importance.