99mTc-labeled field bean protease inhibitor can function as an efficient tumor detecting agent.

Purified field bean protease inhibitor (FBPI) was labeled with 99mTcO4- to ascertain its ability to locate tumors in tumor-bearing rat models. The labeling was done with Sn2+ as a reducing agent and the yield was 95%. It was stable for 2 hr at ambient temperature. The biodistribution study of the intravenously injected radiolabeled FBPI in normal Wistar rats at various time intervals showed a rapid blood clearance from the systemic circulation (approximately 5hr). The complex was predominantly excreted through the renal and the hepatobiliary systems. In vivo distribution and scintiimaging of 99mTc-FBPI were carried out in rats bearing carcinogen-induced mammary tumor or transplanted C6-gliomas. The results obtained were compared with conventional tumor-seeking radiopharmaceuticals such as 99mTc-(V)dimercaptosuccinic acid (DMSA), 201Thallous chloride (TICI) and 99mTc-Citrate. The tumor to muscle (T/M) ratios obtained with 99mTc-FBPI in rat C6 glioma was nearly 2 to 5-fold higher than obtained with all the three conventional tumor-seeking agents. The T/M ratio obtained with 99mTc-FBPI in rat mammary tumor on the other hand appeared to be 2-3-fold higher than noted with 99mTc(V)-DMSA and 201TlCl. The ratio was however comparable with that obtained with 99mTc-Citrate. The study indicated that 99mTc-FBPI has the specific potentials for imaging gliomas and possibly other tumors as well.

131I-MIBG scintigraphy in neural crest tumours.

Radioiodinated meta-iodobenzylguanidine (131I-MIBG) has been widely used for the diagnosis of neuroblastomas, pheochromocytomas, paragangliomas and medullary carcinomas of thyroid. We have developed a procedure for preparation of 131I-MIBG and studied its utility in diagnosis of primary and metastatic neural crest tumours. Studies were carried out in 54 patients. Of them 39 cases were of neuroblastomas, 1 pheochromocytoma; 6 operated medullary carcinomas; 5 paragangliomas; 2 Ewing's sarcoma and 1 Rhabdomyosarcoma; The sensitivity for the detection of primary tumours of neuroblastomas was 94% and for the detection of metastasis was 83%; while in the case of paragangliomas and medullary carcinoma, the sensitivity was 75% and 70% respectively. Our experience in the present study shows that 131I-MIBG scintigraphy is a sensitive and specific diagnostic tool to localise primary and metastatic disease of neural crest tumours.

Biokinetics of 99mTc-labelled liver-imaging agents in an animal model of liver cirrhosis.

Comparable degree of liver cirrhosis, as judged by liver function tests and histopathology, was induced in rats by carbon tetrachloride. Comparative organ distribution of 99mTc-sulphur colloid and 99mTc-phytate was studied in the liver, spleen and lungs of these cirrhotic rats. Compared to controls, the biodistribution of 99mTc-sulphur colloid was found to be affected more than that of 99mTc-phytate in cirrhotic rats, especially at early time intervals.