[Evaluation of 99mTc-PMT delayed imaging in diagnosis of hepatocellular carcinoma]

99mTc-PMT delayed imaging was performed on 199 patients with hepatocellular carcinoma (HCC), and 72 patients with various hepatic diseases, from which HCC should be differentiated. Of the 199 patients with HCC, 128 (64.3%) showed positive results on 99mTc-PMT images. Of these 128, 102 (51.3%) showed increased uptake of radioactivity by the hepatic tumor as compared with the surrounding non-tumorous area of the liver, and 26 (13.1%) showed equal uptake. On the contrary, only 2 (9.1%) of the 22 patients with other malignant hepatic tumors (7 with cholangiocellular carcinoma and 15 with metastatic liver tumors) showed equal uptake of 99mTc-PMT. These findings indicated that 99mTc-PMT delayed imaging was useful for increasing the specificity in diagnosis of HCC. Of the patients with HCC showing increased uptake on 99mTc-PMT images taken 5-hour after the injection of the radioisotope, 26.3%, 69.6%, and 96.0% showed intense 99mTc-PMT uptake by hepatic tumor on 1-hour, 2-hour, and 3-hour images, respectively. These findings indicated that in diagnosing HCC, 5-hour image should be taken only in the patients with a hepatic tumor showing no increased uptake of radioactivity even on 3-hour image. Moreover, the rate of HCC to take up 99mTc-PMT intensely was higher in patients with hepatic tumor showing filling defect on colloid liver image than in those showing no filling defect (p less than 0.001). The points in the assessment of radioactivity uptake by hepatic tumor on 99mTc-PMT delayed image were as follows: Overlapping of radioactivity excreted into the gall bladder or intestine with the radioactivity of the liver tumors, radioactivity retention in the non-neoplastic portion of the liver, and the radioactivity of the dilated intrahepatic bile duct were noted in 6 (2.6%), 15 (6.5%) and 9 (3.9%), respectively, among the 230 patients with focal space occupying lesions. Further, a patient of giant nodular regenerative hyperplasia showed increased uptake of 99mTc-PMT consistent with the hepatic lesion.