Suitable image parameters and analytical method for quantitatively measuring cerebral blood flow volume with phase-contrast magnetic resonance imaging

The aim of this study was to determine suitable image parameters and an ana lytical method for phase-contrast magnetic resonance imaging (PC-MRI) as a means of measuring cerebral blood flow volume. This was done by constructin g an experimental model and applying the results to a clinical application. The experimental model was constructed from the aorta of a bull and circul ating isotonic saline. The image parameters of PC-MRI (repetition time, fli p angle, matrix, velocity rate encoding, and the use of square pixels) were studied with percent flow volume (the ratio of actual flow volume to measu red flow volume). The most suitable image parameters for accurate blood flo w measurement were as follows: repetition time, 50 msec; flip angle, 20 deg rees; and a 512x256 matrix without square pixels. Furthermore, velocity rat e encoding should be set ranging from the maximum flow velocity in the vess el to five times this value. The correction in measuring blood flow was don e with the intensity of the region of interest established in the backgroun d. With these parameters for PC-MRI, percent flow volume was greater than 9 0%. Using the image parameters for PC-MRI and the analytical method describ ed above, we evaluated cerebral blood flow volume in 12 patients with occlu sive disease of the major cervical arteries. The results were compared with conventional xenon computed tomography. The values found with both methods showed good correlation. Thus, we concluded that PC-MRI was a noninvasive method for evaluating cerebral blood flow in patients with occlusive diseas e of the major cervical arteries.