Color functional images of the cerebral blood flow

Functional gamma imaging, in color, was established for regional cerebral blood flow (rCBF) using 133Xe. During 10 min after intracarotid injection of 133Xe in saline, 60 picture frames of the 133Xe clearance curve for the entire hemisphere were obtained. After nine-point smoothing, the rCBF for each of the 4,096 picture elements was calculated by two methods: the half-time method and the height-over-area method. Both the 133Xe clearance half-times and the calculated CBF values were displayed, using 13 steps of color, as functional CBF images of the brain. Images of peak count and total count were also displayed on the same frame of the color television. Forty-six studies, performed on 37 patients with various cerebral disorders, were divided into two types: diffuse and focal. In the diffuse type, a decrease in CBF was noted in cases of normal-pressure hydrocephalus; successful ventriculoperitoneal shunt operations were followed by recovery of CBF. Occlusion of the middle cerebral artery showed up as a wedge-shaped area of decreased CBF, even when the conventional brain scan looked normal. Increased perfusion to a tumor was frequently associated with decreased CBF in the rest of the lateral hemisphere; such a decrease could be improved by surgical removal of the tumor.

A far infrared interferometric spectrometer with a special electronic computer

A far ir interferometric spectrometer with a special electronic computer has been constructed. The interferometer is of the conventional Michelson type. The electronic computer, which consists of an analog computer to introduce apodization and a digital computer to calculate the Fourier cosine transform, is fed with the detector output of the interferometer and is operated by electric pulses from a moiré fringe counter that is part of the mechanism that measures the path difference in the interferometer. The digital computer makes the calculation in parallel for each of one thousand spectral positions during the scanning of the interferogram. It takes 0.45 sec for the calculation at each path difference. A spectrogram can be obtained in 10 min; this includes calculations at one thousand path differences and 2 min for recording. During the scanning, values stored in the memory corresponding to the one thousand spectral positions can be displayed on a synchroscope in order to provide a spectrogram that is low in resolving power at the beginning and high at the end of the scan. Some results obtained with water vapor absorption are shown.