INVIVO REGIONAL QUANTITATION OF INTRA-THORACIC TC-99M USING SPECT - CONCISE COMMUNICATION

Abstract

A whole-body single-photon emission computed tomographic system (SPECT) was used to quantitate the activities of a series of 99mTc point sources in the dog thorax and to evaluate attenuation of a uniform esophageal line source containing a known concentration of 99mTc. A 1st-order attentuation correction and an empirically derived attenuation coefficient of 0.09 cm-1 were used in the SPECT analyses of the intrathoracic point sources. The relationship between SPECT measurements of multiple point-source activities and the same sources measured in air was linear over a range of 100-1000 .mu.Ci (slope 1.08; R2 coefficient of determination 0.97). These data are sufficiently accurate to allow an estimate of the regional activity of radiopharmaceutical in the dog thorax and justify their use in experimental quantitation of regional pulmonary perfusion.