DYNAMIC CONTRAST-ENHANCED T2-ASTERISK-WEIGHTED MRI IN PATIENTS WITH CEREBROVASCULAR-DISEASE

Our purpose was to investigate the potential of dynamic susceptibility contrast-enhanced MRI in assessing regional haemodynamics in patients with cerebrovascular disease. T2-weighted FLASH sequences were perfo rmed on a control group of 10 healthy subjects, 13 patients with unila teral stenosis or occlusion of the internal carotid artery and 6 patie nts with acute onset of neurological symptoms, the observed signal int ensities being converted into concentration-time curves. A gamma-varia te function was fitted to the measured concentration-time curves to el iminate effects of tracer recirculation. In each patient the two cereb ral hemispheres were compared and the difference between the mean tran sit times and the percental change of the regional cerebral blood volu me, calculated for each side. Patients with haemodynamically significa nt unilateral carotid obstruction can be divided into two subgroups: t hose with good and those with poor collateral supply. Patients with go od collateral supply had a slight but not statistically significant in crease in mean transit time and cerebral blood volume on the diseased side, whereas those with poor collaterals had a significant increase c ompared with the control group. In patients with acute onset of neurol ogical symptoms perfusion maps clearly demonstrated the disturbed perf usion at a time when T2-weighted images were still normal. Perfusion i maging is a reliable and noninvasive method of assessing changes in ce rebral perfusion in patients with unilateral carotid stenosis. This MR technique permits monitoring of haemodynamic changes during therapy a nd thus may become an alternative to SPECT and PET scanning. In patien ts with acute occlusion of a cerebral artery, perfusion imaging reveal s the entire perfusion deficit before conventional MRI and thus allows early intervention.