Quantitative evaluation of mean transit times obtained with dynamic susceptibility contrast-enhanced MR imaging and with 133Xe SPECT in occlusive cerebrovascular disease

OBJECTIVE. We report on quantitative mean transit time images obtained using dynamic susceptibility contrast-enhanced MR imaging after an IV bolus injection of a contrast agent. Our study compared cerebral hemodynamics measured using dynamic susceptibility contrast-enhanced MR imaging with the cerebral perfusion reserve obtained using dynamic Xe-133 single-photon emission computed tomography (SPECT). SUBJECTS AND METHODS. Seventeen patients with chronic cerebral artery occlusion or stenosis diagnosed by digital subtraction angiography were examined. Dynamic susceptibility contrast-enhanced MR imaging data were acquired using a mulitshot echoplanar aequence sequence. Our procedure for quantification of mean transit time was based on the lution theory and deconvolution analysis. RESULTS. The increased mean transit time values obtained with dynamic susceptibility contrast-enhanced MR imaging correlated well (r = -0.789, p < 0.0001) with decreased cerebral perfusion reserve determined by performing dynamic 133Xe SPECT before and after administration of acetazolamide. The mean transit time values in the regions with severely decreased perfusion reserve were significantly higher than those in the regions with normal or moderately decreased perfusion reserve (p < 0.0001 and p = 0.0004, respectively). CONCLUSION. Mean transit time images generated from dynamic susceptibility contrast-enhanced MR imaging data could be used to evaluate the extent of cerebral perfusion reserve impairment in patients with occlusive cerebrovascular disease.