The value of multi-delay arterial spin labeling in the evaluation of cerebral perfusion in patients with severe arterial stenosis or occlusion
Objective:To investigate the value of multi-delayed arterial spin labeling(mASL)technique in evaluating cerebral perfusion changes in patients with severe unilateral internal carotid artery or middle cerebral artery stenosis or occlusion.Materials and Methods:Perfusion images obtained from single-delayed pseudo continuous arterial spin labeling(pCASL)and mASL of 34 patients with clinical diagnosis of unilateral internal carotid artery or middle cerebral artery stenosis and occlusion in the Department of Neurology of our hospital were prospectively collected for evaluation of abnormal perfusion area on the side of arterial stenosis.The consistency of two observers in judging the abnormal perfusion area on the stenosis side was evaluated by Kappa consistency test.The region of interest was manually delineated in the abnormal perfusion region and perfusion parameter values were obtained,including cerebral blood flow(CBF2020ms)obtained from pCASL perfusion images and corrected cerebral blood flow(cCBF),arterial arrival time(ATT),arterial cerebral blood volume(aCBV)and relative arterial transit time(rATT)obtained from mASL.Paired sample t test was used to compare the differences of CBF2020ms and cCBF,and independent sample t test was used to compare the differences of ATT on the stenosis side and rATT.Results:According to the results of pCASL and mASL,in 34 patients,the perfusion images of 10 cases were consistent(8 cases were hypoperfusion,2 cases were hypoperfusion with local high signal),and the perfusion images of 24 cases were not completely consistent(3 cases of pCASL showed normal perfusion,mASL showed low perfusion;pCASL showed hypoperfusion with local hyperintensity in 21 cases,and mASL showed hypoperfusion).There was a high degree of agreement between the two observers(Kappa coefficient= 0.788,P<0.001).mASL showed that ATT on the stenotic side was higher than rATT(P<0.001).In patients with hypoperfusion on both pCASL and mASL,CBF2020ms was lower than cCBF(P=0.173).In patients with both pCASL and mASL showing hypoperfusion with local hyperintensity,ATT is prolonged and aCBV is increased.CBF2020ms was significantly higher than cCBF in patients with pCASL showing hypoperfusion with local high signal and mASL showing hypoperfusion(P<0.001).Patients with normal perfusion on pCASL and hypoperfusion on mASL were found to have prolonged ATT but preserved normal aCBV.Conclusions:Multi-parameter cCBF,ATT and aCBV obtained by multi-delay arterial spin labeling technique can evaluate the changes of brain perfusion in patients with severe unilateral internal carotid artery or middle cerebral artery stenosis or occlusion more sensibly and accurately,and provide guidance for clinical diagnosis and treatment.
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