THE DEMONSTRATION OF REGIONAL BRAIN PERFUSION BY DYNAMIC MAGNETIC-RESONANCE TOMOGRAPHY

Bolus injections of gadolinium-DTPA result in high contrast concentrat ion in the distal vessels within the brain and cause a local disturban ce of the magnetic field with a shortening of T2 relaxation time. Puls e frequencies were designed to demonstrate inhomogeneities in the magn etic field. The resultant reduction in T2-weighted gradient echo signa ls was used in order to examine changes in regional perfusion caused b y pathological conditions. Cerebral tumours showed variable perfusion patterns but were always better perfused than surrounding brain tissue ; oedema surrounding the tumour resulted in reduced perfusion. Ischaem ic infarcts showed significant underperfusion compared with control ar eas. In both groups the areas involved were larger on the perfusion sc ans than on T2-weighted images.