Clinical Bone Marrow Scanning with Radioisotopes.

investigators have studied this problem. The autopsy studies of Custer2’3 and Hashimoto4 are directed largely toward efforts to establish the size of the “normal” marrow organ. Shillingford,5 in autopsy studies of patients in heart failure, demonstrated grossly visible expansion of red marrow in long bones. Kramer and Wynne6 made external counts of radioactivity along the extremities after tracer doses of F&” and prepared diagrams illustrating the apparent distribution of erythropoietic marrow. Our initial work on this problem has used colloidal radioisotopes. When administered intravenously, these are rapidly removed from the blood stream by the reticuloendothelial cells. In the marrow, reticuloendothelial activity correlates closely with hematopoietic activity. Engstedt et al.7 used this property to show gross changes of the distribution of the marrow; for example, in polycythemia vera and aplastic anemia. With the Oak Ridge National Laboratory (ORNL) Research Scanner,8’#{176} we have made further studies of the distribution of the hematopoietic marrow. It is hoped now by the use of this and future developments marrow distribution can be measured with considerable detail.