The analysis of radioisotope brain scans by comparison with normal patterns of uptake.

A previously described method for the computer analysis of radioisotope brain scans has been further developed. A patient scan is matched with a series of "normal" scans to find the closest fit and the "normal" scan is then subtracted from the patient scan. The results are displayed in terms of the standard deviation from the normal. In a clinical trial the computer assessments were found to be less accurate than those of two groups of observers. One reason for these disappointing results is related to the simple criteria used to choose and fit the best "normal" to a particular patient scan. A second reason is the optimization of the scanner/photoscan combination to 99Tcm pertechnetate as a brain scanning agent which results in patient-to-patient variation becoming more important. This reduces the potential of a simple numerical analysis to improve results.