Evaluation Of Cerebral Blood Flow In Enhanced Arterial Spin Labeling Magnetic Resonance Imaging

Part 1:Enhanced arterial spin labeling magnetic resonance imaging in healthy middle-aged and elderly:cerebral blood flow perfusion analysisObjectives:To evaluate the mean cerebral blood flow(mCBF),arterial transit time(ATT)and arterial cerebral blood volume(aCBV)in different brain regions of healthy middleaged and elderly using enhanced arterial spin labeling(eASL),and evaluated whether the ATT and age can influence mCBF.Methods:A total of 50 healthy adults range from 45-80 years old were enrolled at the China-Japan Friendship Hospital between January 2021 and December 2021.There were 26 males and 24 femals,mean age 62.8±9.4 years.eASL imaging was performed using a 3.0-T GE magnetic resonance imaging scanner,and the raw data were post-processed using CereFlow software to obtain cerebral perfusion parameters such as mCBF,ATT and aCBV.Paired sample t-tests were used to analyze and compare mCBF,ATT and aCBV of the bilateral frontal lobe,parietal lobe,temporal lobe,occipital lobe and cerebellum for each subject.Age,lateral,anatomical location and ATT regard as independent factors,then the Multiple linear regression was used to determine the factors associated with mCBF in the healthy subjects.Results:Among the 50 healthy subjects,there was significant difference in mCBF between the left and right frontal and parietal(P<0.05).There was no significant difference in ATT between left and right brain regions(P>0.05).Except for cerebellum,the aCBV values of the left frontal lobe,parietal lobe,temporal lobe and occipital lobe were higher than those of the right(P<0.05).Multiple linear regression analysis revealed that local ATT correlated w ith mCBF of left frontal lobe,parietal lobe and left temporal lobe(P<0.05);age was correlated with mCBF in left parietal lobe and left temporal lobe,respectively,(P<0.05).Conclusion:The left and right cerebral blood flow perfusion of healthy middle-aged and elderly are inconsistent.In the right-handed population,the left hemisphere is more sensitive to the regulation of cerebral blood flow.Part 2:Comparative study of pseudo-continuous arterial spin labeling and enhanced arterial spin labeling magnetic resonance imaging in patients with intracranial atherosclerosisObjectives:To compare the differences of cerebral blood flow(CBF)between threedimensional pseudo-continuous arterial spin labeling(3D-pCASL)and enhanced arterial spin labeling(eASL)magnetic resonance imaging in patients with moderate and severe stenosis or occlusion of intracranial artery caused by intracranial atherosclerosis.Methods:A total of 26 patients with moderate and severe stenosis or occlusion of intracranial artery were prospectively enrolled at the Radiology Department of the ChinaJapan Friendship Hospital between January 2021 and December 2021.There were 18 males and 8 femals,mean age 67.3±10.3 years.3D-pCASL and eASL imaging was performed using a 3.0-T GE magnetic resonance imaging scanner,and the raw data were post-processed.By manually drawing the region of interest(ROI)at the measurement sites(bilateral frontal lobe,parietal lobe,temporal lobe,occipital lobe,cerebellum and basal ganglia),the perfusion parameters such as CBF1525ms value,CBF2025ms value,CBF2525ms value,ATT value and CBFTransit-corrected value were obtained.Variance were used to analyze and compare CBF values among CBF1525ms,CBF2025ms,CBF2525ms and CBFTransit-corrected,then the consistence between them were analyze by Bland-Altman diagram.Pearson’s correlation analysis was performed on the relationship between ATT and CBF value from several PLDs.The relationships between the ATT and difference value from CBFTransitcorrected and several PLDs(1525ms,2025ms,2525ms)were evaluated with Pearson’s correlation.After the imaging evaluation of the artery with pathological changes,the blood supply artery with the maximum stenosis rate≧50%was recorded as the diseased vessel.Independent samples t-tests were used to analyze and compare the difference of CBF values between normal brain area and diseased vascular area in CBFTransit-corrected group.Binary logistic regression model was then applied to determine the relationship between diseased vessels and CBF in their blood supply areas.Results:Among the 26 patients,A total of 68 ROIs were in the diseased vascular area with the maximum stenosis rate ≧50%.The highest mean CBF was in CBF2525ms group,the lowest CBF was in CBFTransit-corrected group.The CBF value from several PLDs was statistically significant(F=134.788,P<0.05).Bland Altman analysis shows that CBF1525ms,CBF2025ms,and CBF2525ms are in good consistent with CBFTransit-corrected.Significant correlations were found between ATT and CBF value from several PLDs.Moreover,there was a significant correlation between ATT and difference value from CBFTransit-corrected and several PLDs(1525ms,2025ms,2525ms)(P<0.05).The CBF values in vascular lesion were lower than those of the non-vascular lesion area in the CBFTransit-corrected group(t=7.215,P<0.001).Binary logistic regression analysis revealed that CBFTransit-corrected and ATT were risk factors for predicting moderate or above vascular stenosis(P<0.05).Conclusion:There was a significant consistence between CBF measurements of 3DpCASL and eASL in patients with moderate and severe stenosis or occlusion of intracranial artery.A significant correlation was found between ATT and CBF from several PLDs.ATT and CBFTransit-corrected from eASL are accurate and reliable in evaluating the changes of CBF in intracranial artery stenosis or occlusion.Part 3:Enhanced arterial spin labeling magnetic resonance imaging of cerebral blood flow of the anterior and posterior circulations in patients with intracranial atherosclerotic stenosisObjectives:This study analyzed the hemodynamic differences of the anterior and posterior circulations between patients with intracranial atherosclerotic stenosis(ICAS)and control subjects.We also investigated whether the blood flow velocity of the extracranial carotid/vertebral arteries can influence intracranial cerebral blood flow.Methods:A total of 32 patients with ICAS were prospectively enrolled at the Radiology Department of the China-Japan Friendship Hospital between November 2020 and September 2021.All patients had extensive arterial stenosis,with 17 having cerebral arterial stenosis in the anterior circulation and 15 in the posterior circulation.Thirty-two healthy subjects were enrolled as a control group.Enhanced arterial spin labeling(eASL)imaging was performed using a 3.0-T GE magnetic resonance imaging scanner,and all patients underwent carotid and vertebral doppler ultrasound examinations.CereFlow software was used for post-processing of the eASL data,to obtain cerebral perfusion parameters such as mCBF and ATT.Independent samples t-tests were used to analyze and compare mCBF and ATT of the anterior circulation(frontal lobe,parietal lobe,and insula)and posterior circulation(occipital lobe,cerebellum)between the patient and control groups.The relationships of ATT and mCBF in the two groups were evaluated with Pearson’s correlation.The blood flow velocity of the extracranial internal carotid/vertebral arteries,including the peak systolic velocity(PSV),end diastolic velocity(EDV),mean PSV(mPSV),and mean EDV(mEDV)were compared between the control and study groups using t-tests.Multiple linear regression analysis was then applied to determine the factors associated with mCBF in the two groups.Results:The mCBF of the anterior and posterior circulations in the patient group were lower than those of the control group.The ATT in the patient group were all significantly longer than those of the control group(P<0.05).Except for the insula in the control group,significant correlations were found between ATT and mCBF in all other investigated locations in the two groups(P<0.05).The blood flow velocity of the extracranial internal carotid/vertebral arteries differed significantly between the control and patient groups(P<0.05).The multiple linear regression analysis revealed that in patients with ICAS,mPSV of the vertebral arteries and local ATT correlated with mCBF of the occipital lobes and the cerebellum,respectively,(P<0.05).In contrast,there was no significant correlation within the anterior circulation(frontal lobes,parietal lobes,and insula).Conclusion:There was a significant relationship between ATT and mCBF in patients with ICAS.Extracranial blood flow may influence intracranial hemodynamics in the posterior circulation in patients with ICAS.The maintenance of extracranial blood flow is of great significance in the preservation of intracranial hemodynamics.