Abstract
Our system for measurement of regional cerebral blood flow (rCBF) by Cerebrograph Model 165 and a small digital computer, and some observation about problems on the analysis of the 133Xe clearance curve were reported.
The regional wash out of 133Xe in the brain was measured every second by 16 scintillation detectors of the Cerebrograph. The data collected by the Cerebrograph were fed into the computer which was required with a core memory of 8K 20-bit words, a 32 KW magnetic drum and a magnetic tape.
Flow value of each region and a hemisphere were evaluated by the height over area method and the initial slope method. The data analyzed by computer were printed out corresponding with the position of each detector. In addition to numerical data, the initial parts of logarithmic clearance curves of individual regions were displayed on a CRT for visual information.
In the analysis of the 133Xe brain clearance curve, one of the difficulties was how to determine the starting point (H0) of appeared at initial part of the curve over the brain with major cerebral vessels and to reduce statistical errors, three kinds of our analytical techniques, such as initial exclusion method, extrapolation method and integration method, were considered. The performances of those techniques were studied using digital model method which was reported previously by us. In the conclusion, the extrapolation method thought to give the best results for the data analysis of a multidetector system as the Cerebrograph Model 165.
