MRI Three-Dimensional Intracranial Vascular Anatomical Scanning For Displaying The Outer Contour Of Intracranial Artery

Basi-parallel anatomical scanning(BPAS)is a MR technique that can rapidly display the outer contour of vertebrobasilar arteries.Currently,BPAS combined with 3D time of flight magnetic resonance angiography(3D-TOF MRA)has been widely used in the diagnosis of a variety of vertebrobasilar artery diseases.In practice,there are still some limitations in the imaging of small and tortuous vessels by using BPAS.Due to the limitation of the imaging parameters of BPAS,this technique is mainly applied in the outer contour imaging of vertebrobasilar artery.MRI 3D intracranial vascular anatomical scanning(3D-IVAS)is a T2-weighted three-dimensional fast spin echo imaging with modulated refocusing flip angles technique,which can acquire thinner layer and can be reconstructed in any direction.It can be applied to the outer contour imaging of intracranial artery which walking in the cerebrospinal fluid(vertebrobasilar artery and middle cerebral artery).ObjectiveTo analyze the capacity of 3D-IVAS on displaying the outer contour of vertebrobasilar artery and middle cerebral artery,evaluate the clinical feasibility of 3DIVAS combined with 3D-TOF MRA.MethodsStudy 1:Retrospective analysis was performed on 70 patients who underwent BPAS,3D-IVAS,3D-TOF MRA and high resolution vessel wall imaging(HR-VWI)scanning.A total of 210 vertebral and basilar arteries were enrolled,including 40 normal arteries,135 with atherosclerosis,1 with aneurysm or dissecting aneurysm,14 with vertebral artery hypoplasia,5 with vertebrobasilar dolichoectasia,7 cases of atherosclerosis combined with aneurysm or dissection aneurysm,6 cases of atherosclerosis combined with vertebrobasilar dolichoectasia and 2 cases of atherosclerosis combined with fenestration deformity.The visibility of vertebrobasilar artery on BPAS and 3D-IVAS were scored and compared.The diagnostic efficacy of BPAS combined with 3D-TOF MRA and 3D-IVAS combined with 3D-TOF MRA for each group was compared,and the consistency between 3D-IVAS combined with 3DTOF MRA and HR-VWI was evaluated.Study 2:Retrospective analysis was performed on 224 patients who underwent 3DTOF MRA and 3D-IVAS scanning.A total of 448 middle cerebral arteries were enrolled,including 66 normal arteries,331 with atherosclerosis,10 with moyamoya disease,35 with atherosclerotic moyamoya syndrome,5 with vasculitis associated moyamoya syndrome and 1 case of atherosclerosis combined with aneurysm.The visibility of middle cerebral artery on 3D-TOF MRA and 3D-IVAS were scored and compared.The scores of each group on 3D-IVAS image were compared.ResultStudy 1:The scores of vertebrobasilar artery on 3D-IVAS were higher than BPAS(Z=-6.24,P<0.01).There was no significant difference in the sensitivity of the two techniques among all groups(P>0.05).The diagnostic specificity of 3D-IVAS combined with 3D-TOF MRA was higher than that of BPAS combined with 3D-TOF MRA in the diagnosis of aneurysm or dissecting aneurysm(P<0.01).The diagnostic accuracy of 3D-IVAS combined with 3D-TOF MRA was higher than that of BPAS combined with 3D-TOF MRA in the diagnosis of atherosclerosis,aneurysm or dissecting aneurysm and vertebral artery hypoplasia(P<0.05).The consistency between 3D-IVAS combined with 3D-TOF MRA and HR-VWI was high(k>0.8,P<0.01).Study 2:The scores of middle cerebral artery on 3D-IVAS were higher than 3DTOF MRA(2=-15.10,P<0.01).The scores of normal group and atherosclerosis group were higher than those of moyamoya disease group,atherosclerotic moyamoya syndrome group and vasculitis associated moyamoya syndrome group(P<0.01).ConclusionCompared with BPAS,3D-IVAS showed the outer contour of vertebrobasilar artery more completely and clearly.The diagnostic efficacy of 3D-IVAS combined with 3D-TOF MRA in vertebrobasilar artery diseases was good and had high consistency with HR-VWI.3D-IVAS provided a better view of severely stenotic or occlusive middle cerebral artery than 3D-TOF MRA.3D-IVAS can display the changes like dilation or shrink of the outer contour of intracranial artery,which may help in differential diagnosis of related diseases.