High-Resolution Magnetic Resonance Vessel Wall Imaging Study Of Intracranial Aneurysms

Part I Aneurysm Wall Enhancement Associated with Intracranial Aneurysm Rupture:A Systematic Review and Meta-analysisObject: Aneurysm wall enhancement(AWE)on magnetic resonance vessel wall imaging(MR-VWI)has been proposed as an imaging marker of active aneurysm inflammation and instability.We performed a systematic review and meta-analysis to summarize the association between AWE and aneurysm rupture events.Methods: We performed a comprehensive literature search of MEDLINE,Embase,Cochrane Library,as well as CNKI,Wanfang,and VIP databases for studies evaluating the association between AWE and aneurysm rupture events.Two readers independently screened eligible articles,assessed for risks of bias and extracted study data.Meta-analysis was performed using the Revman 5.3 software package.We performed meta-analysis using a fixed-effects model or a random-effects model when there was high between-study heterogeneity.Study heterogeneity was calculated using Cochrane Q test and I2 statistic.Publication bias was examined by Begg–Mazumdar test using the STATA 13 statistical package.Results: Eight studies(5 English and 3 Chinese)with 700 subjects,including 160(22.9%)ruptured aneuryms,met eligibility for systematic review.We found a significant positive overall association between AWE and aneurysm rupture,with an odds ratio(OR)of 35.09(95% CI,15.32~80.38,p<0.01).No significant heterogeneity or publication bias was present in the meta-analysis.In the analysis of circumferential AWE,the strength of association between circumferential AWE and aneurysm rupture was significant in small aneurysms(OR 25.99,95% CI 6.54~111.79,p<0.01),but limited in large aneurysms(p=0.78).Conclusions: AWE on MR-VWI is significantly associated with aneurysm rupture.Circumferential AWE helps to identify high-risk small aneurysms.AWE on MR-VWI may become a promising imaging marker to predict aneurysm behavior.Part II Wall Enhancement Features of Symptomatic Intracranial Aneurysms: A Magnetic Resonance Vessel Wall Imaging StudyObjective : The aim of this study was to explore the high-risk vessel wall enhancement features of symptomatic unruptured intracranial aneurysms(UIAs)by using magnetic resonance vessel wall imaging(MR-VWI).Methods:Consecutive patients with DSA and clinical confirmed symptomatic UIAs were included in the case group between July 2014 and December 2017.During the same period,patients with asymptomatic UIAs were matched 1:1 on the basis of age,sex,aneurysm size and location into the control group.All patients underwent 3T MR-VWI.Patient demographics,aneurysm morphological parameters and wall enhancement types were compared between symptomatic and control groups.Results:78 patients(mean age 57.4±10.1 years,26 male and 52 female)with symptomatic and matched asymptomatic UIAs were included.There was no significant difference in patient demographics and aneurysm morphological characters between the symptomatic and control groups(p>0.05).Aneurysm wall enhancement was more prevelance in symptomatic(74.3%)than in asymptomatic UIAs(46.1%)(p<0.05).There was no significant difference in wall enhancement degree between symptomatic and asymptomatic aneurysms(p>0.05).However,UIAs with heterogeneous and diffuse,other than focal,wall enhancement were more likely to be symptomatic(p<0.01).Conclusions:UIAs with wall enhancement,especially heterogeneous and diffuse wall enhancement,are more likely to be symptomatic.Aneurysm wall enhancement on MR-VWI may be a useful tool to identify high-risk symptomatic UIAs.Part III Intracranial Unruptured Aneurysm: Relationship between Aneurysm Wall Enhancement and Rupture Risk FactorsObjectives: The aim of this study was to ascertain whether intracranial unruptured aneurysm wall enhancement(AWE)identified on magnetic resonance vessel wall imaging(MR-VWI)correlated with aneurysm rupture risk factors and the estimated rupture risk.Methods: Consecutive patients with DSA confirmed unruptured intracranial aneurysms(UIAs)were enrolled between July 2014 and December 2017.All patients underwent 3T MR-VWI.Patient demographics were extracted from our institutional database,morphologic parameters were measured on DSA,and AWE types were graded on MR-VWI.One-and five-year rupture risk of UIAs were estimated using the UCAS and PHASES calculator,respectively.Parameters associated with AWE were analyzed using univariate and multivariate logistic regression.Association between AWE type and morphological parameters as well as estimated rupture risk was analyzed using the Spearman's rank correlation.Results: 77 patients(mean age 58.4±10.8 years;39 male and 38 female)with 88 UIAs were included.Multivariate logistic regression analysis showed that non-internal carotid artery location(OR 3.4,95% CI 1.6~7.1)and aneurysm size(OR 1.9,95% CI 1.3~2.7)were independently associated with AWE(p<0.05).UIAs with AWE had significantly higher estimated rupture risk than UIAs without AWE(p<0.001).Stronger and larger area of AWE were positively correlated with aneurysm size,size ratio and estimated rupture risk(Spearman R2?0.30,p<0.05).Conclusions: AWE appears to reflect higher risk aneurysm properties,and this study specifically observed a strong correlation of AWE with estimated short and medium-time rupture risk.These findings suggest that AWE may be useful in imaging-based prospective assessment of aneurysm rupture risk.Part IV Intracranial Dissecting Aneurysm: A High-resolution Magnetic Resonance Vessel Wall Imaging StudyObjective: Intracranial dissecting aneurysm(IDA)is the main cause of stroke in younger adults.We aimed to evaluate the luminal and vessel wall features between different IAD types by using high-resolution magnetic resonance vessel wall imaging(MR-VWI).Methods: Consecutive patients with clinically suspected IDA were enrolled between January 2016 and September 2017.All patients underwent 3T MR-VWI.IDA luminal and vessel wall features were qualitatively and quantitatively assessed.IDAs were assigned into classical,segmental dilatation,dolichoectasia and giant aneurysm types according to morphological features.Differences of patient demographics,luminal and vessel wall features were compared among the four IDA types.Results: 49 patients(mean age 52.7±11.8 years;35 male and 14 female)were enrolled in this study.IDAs were classified into classical(n=27),segmental dilatation(n=7),dolichoectasia(n=12)and giant aneurysm(n=3)types.Classical type IDA occurred more often with non-dilatation luminal pattern as well as intimal flap and double-lumen(p<0.05).Luminal dilatation with intramural thrombus formation was more frequently observed in the segmental dilatation type(p<0.05).Obvious local mass effect was more prevalance in the dolichoectasia and giant aneurysm types with higher aneurysm maximum outer diameter,length,wall thickness index and remodeling index(p<0.001).Most(98.0%)IDAs showed inner and outer wall enhancement and the degree of wall enhancement decreased over time(p<0.01).Focal wall enhancement was more often observed in segmental dilatation type IDA,and diffuse wall enhancement was more frequently seen in classical,dolichoectasia and giant aneurysm type(p=0.047).Conclusion: High-resolution MR-VWI offered clear visualization of various luminal and vessel wall features in different IDA types and pathological status.MR-VWI may become a useful tool for non-invasive surveillance of IDA.