Differential Diagnosis of AH109A Tumor and Inflammation by Radioscintigrap 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.