The presentation and its clinical diagnostic value of 3D-FLAIR in large vestibular aqueduct

LI Honglei; LI Xiaoyu; LI Xiaoqin; LI Jinye; HU Na; SUN Lixin; WANG Linsheng

Abstract：Objective To explore the presentations of the 3-dimensional fluid attenuation reversal recovery sequence(3D-FLAIR)and its clinical application value in the large vestibular aqueduct(LVA).Methods A retrospective analysis was con-ducted on 328 cases(649 ears)of LVA with HRCT and MRI[3-dimensional sampling perfection with application-optimized con-trasts by different flip angle evolution(3D-SPACE)and 3D-FLAIR].Based on the range of the high signal in the ED and ES of LVA on 3D-FLAIR,they were classified into 3 types:Type I,showing no high signal on 3D-FLAIR;Type II,Partial high signal on 3D-FLAIR;and Type III,appearing complete high signal on 3D-FLAIR.Then,we calculated the incidence of high signal in the inner ear and ED and ES on 3D-FLAIR,as well as the complete displaying rate of ED and ES in the LVA ears on 3D-SPACE and 3D-FLAIR,analyzed their differences using chi square test,and discussed the reasons for false negatives in LVA ears diag-nosed by 3D-SPACE.Results The incidence of high signal in the inner ear,ED and ES of 328 LVA patients with 649 ears was 49.0%and 91.7%,respectively.The range and intensity of the high signal intensity on 3D-FLAIR in the ED and ES of the af-fected ears were variable.Among them,54 ears(8.3%),570 ears(87.8%),and 25 ears(3.9%)belonged to type I,II,and III,respectively.The complete displaying rates of ED and ES in the affected ear by 3D-SPACE and 3D-FLAIR were 93.7%and 4.2%,respectively,and the difference between them was statistically significant(χ2=1040.7,P＜0.05).The accuracy rates of 3D-SPACE and 3D-SPACE+3D-FLAIR were 95.7%(621/649)and 100%(649/649),respectively,and there was statistically significant difference between them(χ2=28.6,P<0.05).The analysis of 19 false negative LVA cases(28 ears)on 3D-SPACE was as follows:the vestibular aqueduct(VA)in two LVA ears presented markedly dilation on HRCT,and the signals in the af-fected ED and ES were deadly low similar to adjacent bone on 3D-SPACE,which made them difficult be displayed,while they could be clearly displayed as high signal on 3D-FLAIR.In the other 26 LVA ears,the degree of the dilation of the affected VAs was relatively mild or normal-like on HRCT.The degree of dilation of the inner and outer ossous parts of the ED and ES was also relatively mild,and the signal in the distal portions was complex,which made the ED and ES be difficult to display on 3D-SPACE,but shown high signal could be easily diagnosed on 3D-FLAIR.Conclusion Abnormal signals in the inner ear,ED and ES of LVA patients might be one of the MRI appearing features.3D-FLAIR is not suitable for standalone application in LVA diagnosis,and its combination with 3D-SPACE can help improve the diagnostic accuracy of some LVA.