BACKGROUND AND PURPOSE:There is increasing evidence implicating microvascular impairment in MS pathogenesis. Perfusion imaging offers a unique opportunity to investigate the functional impact of GM pathology. We sought to quantify differences in MR imaging-based bookend-derived cerebral perfusion between cognitively impaired and nonimpaired patients with SPMS.

BACKGROUND AND PURPOSE:Cognitive impairment is a common, disabling symptom of MS. We investigated the impact of cerebral perfusion and brain and lesion volumetry on cognitive performance in 45 patients with SPMS by using MR imaging.

The singular value decomposition deconvolution of cerebral tissue concentration-time (C-T) curves with the arterial input function (AIF) is commonly used in dynamic susceptibility contrast (DSC) cerebral perfusion MR imaging. However, it is sensitive to the time discrepancy between the arrival of the bolus in the tissue C-T curve and the AIF signal. This normally causes inaccuracy in the quantitative perfusion maps due to delay and dispersion effects. A comprehensive correction algorithm has been achieved through slice-dependent time-shifting of the AIF, and a delay-dependent dispersion correction model. The correction algorithm was tested in 11 healthy subjects and 3 ischemic stroke patients scanned with a quantitative perfusion pulse sequence at 1.5T. A validation study was performed on 5 patients with confirmed cerebrovascular occlusive disease scanned with MRI and positron emission tomography (PET) at 3.0T. A significant effect (p<0.05) was reported on the quantitative cerebral blood flow and mean transit time measurements (up to 50%). There was no statistically significant effect on the quantitative cerebral blood volume values. The in vivo results were in agreement with the simulation results, as well as previous literature. This minimizes the bias in patient diagnosis due to the existing errors and artifacts in DSC imaging.

Purpose:To compare quantitative values of cerebral blood flow (CBF) derived from dynamic susceptibility contrast (DSC) magnetic resonance (MR) imaging with reference standard positron emission tomography (PET) in patients with confirmed cerebrovascular occlusive disease. Materials and Methods:Local institutional review board approval and informed consent were obtained for a prospective study of 18 patients (six men, 12 women; age range, 28-71 years; mean age, 45 years 6 10.4 [standard deviation]) with angiographically confirmed Moyamoya (n = 8) or internal carotid artery occlusions (n = 10). DSC MR images and oxygen 15-labeled water (H 2 [15 O]) PET images were acquired on the same day. DSC images were postprocessed to yield parametric images of CBF (in mL/100 g/min), coregistered, and analyzed using grid-based regions of interest. Mean values of CBF in each region of interest from MR imaging and PET data sets were compared. Correlations for each patient were determined and overall agreement between pooled MR imaging and PET CBF was reported using linear regression analysis and Bland-Altman plots. Results:Strong correlations (r 2  0.55) were found between MR imaging and PET CBF values in all patients. Use of the bookend approach was found to underestimate CBF predictably across the patient cohort (mean slope, 0.82; standard deviation, 0.18; slope of aggregated data, 0.75). This allowed for a simple rescaling of MR imaging values producing strong agreement with PET values in the aggregated data (r 2 = 0.66; slope = 1.00; intercept = 0.00). Conclusion:The