A Comparative Study Of Intracranial Atherosclerotic Stenosis In Multi-modal Magnetic Resonance Perfusion-weighted Imaging

Part I A comparative study of lesion detection for transient cerebral ischemic attack in multi-parameter arterial spin labeling and dynamic susceptibility contrast enhanced cerebral perfusion-weighted imagingObjective:To evaluate the potential clinical usefulness of three-dimensional pseudo-continuous arterial spin labeling (3D pCASL) perfusion-weighted imaging in transient ischemic attack (TIA) by comparing with dynamic susceptibility contrast (DSC) enhanced perfusion-weighted imaging.Methods:We enrolled 39 consecutive patients with suspected TIA. All patients underwent multi-modal MRI including magnetic resonance angiography (MRA), diffusion-weighted imaging (DWI), DSC, and 3D pCASL with two post-labeling delay times (PLD=1.5s and 2.5s) within 24 hours. Cerebral blood flow (CBF) values from ASL and time to the maximum of the tissue residual function (Tmax) from DSC were calculated using AW workstation (GE Healthcare). DWI and MRA were applied to detect acute cerebral infarction and intracranial artery stenosis. Two neuroradiologists who were blinded to clinic information of patients assessed the presence of perfusion deficit, ischemic lesion and the lesion sites both from 1.5s,2.5s PLD 3D pCASL-CBF and DSC-Tmax independently, and then graded them respectively. Wilcoxon signed rank test were performed to test the differences of ranking grades between 1.5s,2.5s PLD 3D pCASL and DSC. Wilcoxon signed rank test analyzed to test the frequency of lesion detection differences between 3D pCASL-CBF, DSC-Tmax and MRA combining DWI methods.Results:There were no significant differences of lesion detection rate between 3D pCASL-CBF (including PLD 1.5s and 2.5s) with DSC-Tmax, DSC-Tmax,3D pCASL -CBF (PLD2.5s), and MRA combining DWI methods. However,3D pCASL-CBF (PLD1.5s) was more sensitive than MRA combining DWI methods in detecting ischemic lesions.3D pCASL-CBF (PLD 1.5s) is the most sensitive sequence in detecting the hypoperfusion areas, followed by DSC-Tmax, and 3D pCASL-CBF (PLD2.5s).Conclusions:Compared with traditional DSC PWI, three dimensional pCASL is more convenient and without radiational effect. Our study revealed that 3D pCASL with PLD 1.5s was more sensitive than it with longer PLD in detecting ischemic lesions in patients with TIA.Part II Quantitative study using multi-parameter arterial spin labeling magnetic resonance perfusion imaging in patients with intracranial atherosclerotic stenosisObjective:Cerebral blood flow (CBF) values were measured in patients with severe intracranial atherosclerotic stenosis using enhanced three-dimensional pseudo-continuous arterial spin labeling (e-pCASL) with continuous multi-post labeling delay time (PLD), dynamic susceptibility contrast enhanced perfusion-weight imaging (DSC PWI) and three-dimensional pseudo-continuous arterial spin labeling (pCASL) sequences. The difference and correlation among these quantitative methods was evaluated.Methods:Consecutive 39 patients with severe middle cerebral artery stenosis (70%-99%) were enrolled in this study. All patients performed routine MRI, MRA, e-pcASL,3DpcASL and DSC PWI sequences. Blood supply territory of the stenosed artery was outlined as ROI in the ipsilateral side and mirror ROI were applied in the contralateral side. Ratios of CBF were calculated as value of ROI/value of mirror ROI. SNK variance analysis was conducted to test. Furthermore, ATT and TTP were calculated by e-pCASL and DSC PWI, respectively. Stratified analysis of variance and Pearson were employed to analysis the difference and the correlation of e-pCASL CBF ratio. pCASL CBF ratio and DSC PWI rCBF ratio based on ATT and TTP.Results:Correlation of e-pCASL CBF ratio and DSC PWI rCBF ratio (r=0.871) were stronger than pCASL CBF ratio and DSC PWI rCBF ratio (r=0.642). Moreover, methods of perfusion and TTP had no different CBF ratio. The correlation of pCASL CBF ratio and DSC PWI rCBF ration was affected grouped by ATT.Conclusions:Compared with pCASL, e-pCASL with multiple post labeling delay time has better consistency and correlation with DSC PWI in the quantitative measurement of hypoperfusion pattern. Furthermore, e-pCASL is a accurate> simplified, noninvasive and repeatable perfusion sequence and is not affected by ATT.