Digital computer analysis and display of the radionuclide scan.

Radioisotope scanning of the thyroid was introduced in 1951 by Cassen, et al ( 1 ). By 1956 this technique had been successfully applied to the liver, brain and several other sites ( 2-5 ) . Today a large number of scanning procedures are in use. Despite wide acceptance of the method there is still much to be desired in our ability to interpret scans. Coffin, et at ( 6 ) , for example, encountered an mci dence of 27 per cent false negative studies in scans for hepatic masses using Au198 colloid. At our own institution, in 30 proved space-occupying lesions of the brain, a correct diagnosis was made in only 21 patients by the use of scanning techniques ( 7) . Much of the difficulty at present results from subjective methods of interpretation. There is great variation in the way any two experts would interpret a particular scan and even considerable variation in the way one mdi vidual would read a given scan from day to day. There is always random varia tion in neighboring densities in scans and some means of applying statistical test ing to this variation is needed. The following is the preliminary report on a method which promises to fill this need.