A subtraction scintigraphy using 197HgCl2 and 131I-RISA for the diagnosis of lung cancer

Subtraction scintigraphy using 197HgCl2 and 131I-RISA was performed for the diagnosis of lung cancer. By use of data processing, a tumor image was extracted from the original image of 197HgCl2. Signals from a scinticamera were fed into 64 x 64 memory through a matrix input controller, and transferred from the computer to a magnetic tape recorder. First, data of 197HgCl2 was obtained, and secondly, data of 131I-RISA was obtained. Both data on magnetic tape were fed into the computer. Then these were displayed as images on a graphic display device. The location for subtraction was displayed by the cursor on the image of 197HgCl2. This positioned information was transferred to the computer in order to calcurate the count ratio (subtraction ratio) between the two images. Counts on the image of 131I-RISA were multiplied by the subtraction ratio. This normalized image (131I-RISA image) was subtracted from the image of 197HgCl2. In this subtraction, the portion of non-specific concentration on the 197HgCl2 image was erased, and hyperfixation of the 197Hg in the primary and metastatic foci of lung cancer was clearer than the original unprocessed image of 197HgCl2. Uptake ratio of 197Hg and 131I in regions of interest was also discussed. (auth.)