Anger camera imaging of perfused and nonperfused brain tissue with intra-arterial 133Xenon technique

The regional cerebral blood flow, the regional blood flow distribution, and the regional distribution of perfused (= vital) brain tissue been imaged with a digitalized conventional Anger camer. An analog scaler was placed behind the PM-tubes to reduce dead-time loss. The input pulse rate was doubled to counteract the effect of scaling on counting statistics, and the gamma emission was filtered through 1 mm of brass to increase the fraction of the integral count rate within the 40% window. In this way the 31 keV peak disappears, and Compton scatter and disturbing coincidences are markedly reduced. This improves spatial resolution. The flow parameters are imaged regionally in 3 X 3 mm2 matrix elements after flat field correction and smoothing. The matrix is 64 X 64 interpolated to 128 X 128. Patient studies emphasized the importance of imaging the distribution of perfused and nonperfused tissue in cases of infarctions, dilacerations, etc., where angiography and conventional brain scanning may often be negative.