Differential diagnosis of AH109A tumor and inflammation by radioscintigraphy with L-[methyl-11C]methionine.

Abstract

For the evaluation of tumor imaging with l‐[methyl‐11C]methionine (11C‐Met), a basic study on the differentiation of tumor from inflammation with 11C‐Met and a comparison of the diagnostic value of the image with that obtained using 67Ga citrate, a conventional scintigraphic agent, are important. 11C‐Met accumulations into inflammatory lesions, AH109A tumor and normal tissues of rats were examined by means of a tissue distribution study. Aseptic inflammatory lesions on the back of Donryu rats induced by croton oil and 1.5% carrageenan showed significantly lower accumulations of 11C‐Met than the AH109A tumor. Histologically, croton oil induced granulomatous inflammation and carrageenan, acute exudative inflammation. Whole‐body antoradiography with l4C‐Met, a substitute for 11C‐Met, was negative in the carrageenan lesion and showed a slightly increased activity at the periphery of the croton oil lesion, in contrast with the high tumor activity. Whole‐body autoradiogra‐phy with 67Ga citrate was performed to compare the imaging ability with that of 14C‐Met; it showed high activities in the tumor, bone, and intestine, and a broad increased activity at the periphery of the croton oil lesion, but was negative in the carrageenan lesion. 11C‐Met accumulations in the inflammations were very low and clinical application with positron emission tomography, should be useful for the differential diagnosis of tumor from inflammation.