Localization of Intracranial Neoplasms with Radioactive Isotopes

Abstract

The method of detecting and localizing brain tumors by external measurement of radiations emitted by radioactive di-iodo-fluorescein concentrated within the tumor was originated by G. E. Moore and his group at the University of Minnesota in 1947 (3). They first reported on a group of 77 cases, including 49 verified tumors, of which 25 (51 per cent) were correctly localized. A more recent report from this group concerned 26 proved brain tumors from a group of 71 patients studied, of which 17 (65 per cent) were correctly localized (4). The interest in this diagnostic method was heightened by a paper of Ashkenazy, Davis, and Martin (1), who attained an accuracy of 91 per cent in 95 patients with verified brain tumors. Woolsey, Thoma, and Mack (12), using the same method, reported a series of 114 patients with 30 verified brain tumors, of which 24 were correctly localized. Svien and Johnson (8) in a preliminary study found the method appproximately 40 per cent accurate. Schlesinger (5), in discussing his experience with 100 cases at the Memorial Hospital in New York, presented no statistical analyses, but emphasized the limitations of the procedure. DeWinter (10), after detecting only 1 out of 20 verified cases, concluded that the method was of little value in tumor localization. Although he used di-iodo-fluorescein, his detecting equipment and method of counting differed markedly from those used by others, which was probably partly responsible for his lack of success. Radioactive substances other than di-iodo131-fluorescein have been tested. Selverstone and Sweet (6) used K42 for both internal and external localization. With external counting they were able to localize correctly 8 of 10 confirmed supratentorial tumors and none of 5 subtentorial neoplasms. Susen, Small, and Moore (7), also using K42, correctly detected 8 of 12 supratentorial tumors, but only 1 of 9 located subtentorially. Apparently heavy concentrations of K42 in the suboccipital musculature set up a high background which may obscure any differential in radioactivity arising from a posterior fossa neoplasm. Radioactive iodinated human serum albumin and radioactive sodium iodide (2, 4) have been used more recently by the Minnesota group. Radioactive iodinated human serum albumin is retained in the blood stream longer and permits repeated counts to be made. It has the possible disadvantage of requiring a twenty-four-hour delay after administration before counting can be done, and requires previous treatment with Lugol's solution to block thyroid uptake. We began using radioactive isotopes to study patients suspected of having organic neurologic disease in January 1951 and have studied 250 patients as of Nov. 1, 1952. Our technic has closely approximated that used by both the Northwestern and Minnesota groups. We are presenting an analysis of our findings in 200 patients studied for a long enough period to permit adequate follow-up and evaluation.