QUANTITATION OF BRAIN PERFUSION WITH TC-99M-BICISATE AND SINGLE SPECTSCAN - COMPARISON WITH MICROSPHERE MEASUREMENTS

This study describes and validates in a preliminary manner a method to measure the steady-state influx constant (K-i) of Tc-99m-bicisate wit h one single photon emission computed tomography (SPECT) scan. The met hod is based on the analysis of the arterial concentration of the radi oactivity. The results of this quantitation procedure were compared wi th regional CBF (rCBF) measurements made using Tc-99m-microspheres (MI ). Two quantitative indexes of perfusion, fractional brain uptake (FBU ) and normalized (with cerebellum) brain uptake (NBU), were also evalu ated. Two SPECT studies were performed on seven cardiovascular patient s who had no signs of neurological disease. In the first of these, Tc- 99m-bicisate was used, while in the other, which was performed 2 days later, MI were injected into the left heart ventricle. The values of t he FBU, NBU, and K-i of Tc-99m-bicisate were calculated in several gra y and white matter brain regions of interest (ROIs) and compared with the rCBF values measured with MI in coupled ROIs. Mean FBU values were 0.00008 +/- 0.00002 and 0.00004 +/- 0.00001 in the gray and the white matter, respectively. Mean NBU values were 0.99 +/- 0.04 and 0.54 +/- 0.05, mean K-i values were 0.36 +/- 0.06 and 0.19 +/- 0.03 ml g(-1) m in(-1) and mean rCBF values were 0.51 +/- 0.04 and 0.27 +/- 0.04 ml g( -1) min(-1) in gray and white matter, respectively. Analysis of varian ce of the regression gave different F values for the regressions with rCBF of FBU (F = 19, n = 126), NBU (F = 289, n = 112), and K-i (F = 11 7, n = 126). The regression of K-i versus rCBF was K-i = 0.08 +/- 0.55 rCBF.