Estimation of Bone Marrow Blood Flow with ^113mIn-EDTA Chelate and ¹³³Xe

Abstract

An estimation of the bone marrow blood flow was undertaken by introducing various radioisotope preparations into the iliac marrow of the rabbit and measuring T_1/2 obtained from their wash-out curves. In the normal animals, the right and left symmetry was obvious; with ^113mIn-EDTA, T_1/2 was 4.46±1.00min in the left iliac marrow and 4.42±1.06min in the right. Studies with ¹³³Xe showed the same results. Vasodilation and vasoconstriction affected the disappearance rate of ^113mIn-EDTA. With a vasodilator drug, a pronounced reduction in T_1/2 was observed, and with a vasopressor, an extreme elongation. An extreme elongation to 21.28±7.24min was seen in experiments with ^113mInCl₃. A rough estimate with ^113mIn-colloids revealed an identical result. These suggest a mechanism of clearance of ^113mIn-EDTA and ¹³³Xe from the marrow other than phagocytosis by the marrow reticuloendothelial system. Thus, measurement of the disappearance rate, T_1/2, of ^113mIn-EDTA and ¹³³Xe from the marrow cavity appears to be an appropriate estimation of the bone marrow blood flow.