A New Agent for Splenic Scanning: BMHP

Abstract

All Scintillation scanning technics depend upon a physiological concentrating mechanism of the administered radioisotope within the organ to be surveyed. It is only relatively recently that visualization of the spleen has been reported (5). This has been accomplished by various methods modifying red blood cells labeled with radioactive chromium 51 to promote their rapid selective sequestration from the circulation, primarily within the functioning spleen (2). Although at times successful, these methods have generally yielded scans of poor diagnostic quality, related to the radioisotope employed and to the erratic nature of sequestration of the altered red cells. The search for better agents for splenic scanning has continued. In 1957, Kessler, Lozano, and Pitts (1) found 1-iodo-mercuri-2-hydroxypropane concentrated in the spleen of dogs following intravenous injection. This discovery was not utilized until 1963 when Wagner (3) postulated that the splenic concentration might result from sequestration of red blood cells chemically damaged by the mercurial compound. MHP (1-mercuri-2-hydroxypropane) using mercuric nitrate labeled with mercury 203 was synthesized. Subsequently, the bromide form, bromo-1-mercuri-2-hydroxypropane (BMHP), was found to be the most avidly bound to red blood cells of all the mercurial compounds. The cells were moderately damaged as evidenced by the rapid accumulation in the spleen. The binding occurred even when the compound was injected intravenously only, eliminating the necessity for time-consuming incubation technics for labeling. This material (Hg203-BMHP) was then prepared for us commercially,2 and initial clinical studies were undertaken. Subsequent studies were carried out with Hg197 MHP BMHP and Hg197 MHP. Technic Metabolism and excretion studies and splenic scanning were performed in 15 patients to verify and expand data received from Wagner (3). Following venipuncture, 100 microcuries of Hg203-BMHP was mixed in the syringe with the patient's blood in a concentration of 1 mg of mercury per 2 ml of whole blood. This was immediately re-injected and serial blood samples were taken at thirty-minute intervals for the first three hours and then hourly for six hours. Total urine and stool collections were obtained for four days. Integral counting over the spleen, liver, kidneys, and sacrum was performed at varying time intervals for three days. The abdomen was scanned two hours after the administration of the radioisotope. Chromatographic urine studies were performed, and the patient's blood count and blood volume were determined. The 15 studies indicated that the BMHP-labeled red blood cells cleared the circulation with a half-time of twenty to one hundred minutes, supporting the data of Wagner in 110 patients (4).