Imaging Study Of Carotid Stenosis And Its Hemodynamic Status

Objective: To evaluate the reliability of vascular wall MRI in the diagnosis of cranial and cervical artery stenosis and ulcerous plaques,and to investigate the hemodynamic changes of carotid stenosis.Methods: 85 patients,including 49 patients with carotid stenosis(65 vessels)and 36 patients with middle cerebral artery stenosis(36 vessels),were confirmed by DSA in our hospital.They were performed MRI of the vascular wall of the cranial and cervical vessels within 1 week after DSA examination to evaluate the reliability of the vessel wall MRI on the degree of stenosis of carotid artery and middle cerebral artery and the diagnosis of ulcerous plaques.Hemodynamic examination was performed in patients with carotid atherosclerotic plaque.Nine patient(11 vessels)underwent 4D Flow MRI,while six(10 vessels)underwent carotid CTA.Five of them(5 vessels)were performed MRI and CTA examinations at the same time.4D Flow MRI data was visualized by post-processing software CVI 42.0,while CTA data was visualized by CFD simulation modeling.Hemodynamic parameters were measured in the upstream,downstream and narrow center of carotid stenosis.Hemodynamic differences in various parts of carotid stenosis were analyzed,and the correlation of the results of the two methods was compared.Five volunteers(5 vessels)were selected for carotid vascular wall MRI and 4D Flow MRI,and the blood flow status was analyzed.The measurement plane was located at the distal end of the common carotid artery,the common carotid bifurcation and the proximal end of the internal carotid artery.The blood flow state in the adjacent of stenotic vessels of patient was compared with that of the volunteers.Results: There was a good consistency between vessel wall MRI and DSA in evaluating the degree of carotid stenosis.The sensitivity and the specificity of the diagnosis of ulcerous plaques was 50% was 94.11% respectively.The blood flow state of the place of carotid stenosis changed significantly,while the blood flow velocity in the stenosis increased.The wall shear stress(WSS)in the upstream and central of the stenosis increased,while the WSS on the downstream of the stenosis was low.Besides,the wall pressure in the stenosis decreased.Compared with normal people,the maximum flow rate and maximum flow velocity of normal blood vessels in stenosis patients were smaller.4D Flow MRI and CFD showed good correlation in blood flow changes.Conclusion: MRI of vessel wall can evaluate cranial and cervical artery stenosis and ulcerated plaque reliably.4D Flow MRI and CFD can measure the hemodynamic parameters of carotid stenosis and analysis to them quantitatively.