Application Of 3D High-Resolution Vessel Wall Imaging With MRI In The Diagnosis And Evaluation Of Unruptured Intracranial Aneurysms

ObjectiveTo evaluate the value of three-dimensional high-resolution vessel wall imaging with MRI(3D HR-VWI)in evaluating the characteristics of unruptured intracranial aneurysms.Materials and MethodsThirty-one subjects,comprising 37 aneurysms,who had presented to our hospital from January 2017 to December 2018 were enrolled in this retrospective study.They all underwent 3D time-of-flight magnetic resonance angiography(3D-TOF MRA)to verify the location of unruptured intracranial aneurysms,then conventional magnetic resonance imaging(MRI)including T1WI,T2WI,T2-FLAIR,besides pre-and post-contrast 3D HR-VWI were performed.Furthermore,25 of these patients,with 27 aneurysms,had accepted DSA examination one week later.We measured the neck width,maximum width,maximum height,perpendicular height,size(maximum diameter),and parent vessel diameter of the aneurysms on the 3D-TOF MRA,3D HR-VWI,and DSA images.Paired-sample Student’s t-tests were performed to compare measurements obtained from the 3 imaging techniques.The wall enhancement index(WEI)and the contrast ratio of the aneurysm wall against the stalk(CRstalk)were calculated,and morphological metrics including size,location,shape,aneurysm angle,AR(aspect ratio),and SR(size ratio)were obtained.Pearson or Spearman correlation analyses,depending on variable type,and multiple linear regression analyses were used to identify the risk factors significantly correlated with WEI,CRstaik.We compared the ability of 3D HR-VWI and conventional T1WI,T2WI,T2-FLAIR sequences on the detection rate,signal characteristics of the intralunimal thrombus,as well as the contrast of mean signal intensity between thrombus and normal brain.ResultsMeasurements with 3D HR-VWI demonstrated no significant difference compared with the gold standard of DSA(p>0.05),but measurements of the neck width with 3D-TOF MRA were significantly smaller(p<0.05)than in DSA.Only irregular-shape was entered into the multiple linear regression analysis,and was found to be significantly associated with higher WEI and CRstalk values(standardized β=0.431,0.395,respectively,p<0.001;corrected coefficients of determination were 0.593 and 0.460,respectively).Seven cases of intraluminal thrombus were identified in the aneurysms using 3D HR-VWI sequences,and only four of them were observed in normal T1WI and T2WI.Heterogeneity within the clot with indistinct margin was more evident in the conventional T1WI,T2WI,T2-FLAIR sequences than in the 3D HR-VWI.Contrast of the mean signal intensity between thrombus and normal brain was greatest with 3D HR-VWI(1.6±0.7),followed by normal T2-FLAIR(1.5± 0.6),T1WI(1.4±0.3)and T2WI(1.3±0.7)imaging.Conclusion3D HR-VWI had higher accuracy in measuring the morphological parameters,especially the neck width than 3D-TOF MRA,and it was found to be superior to normal T1WI,T2WI,T2-FLAIR sequences in characterizing intraluminal thrombus within aneurysms.It also allowed quantitative assessment of circumferential aneurysmal wall enhancement.