微小表面线圈高分辨MR扫描在原发性面神经肿瘤诊断中的应用价值

Value of high-resolution MR scan using micro-surface coil in the diagnosis of primary facial nerve tumors

目的探讨微小表面线圈高分辨MR扫描在原发性面神经肿瘤诊断中的临床应用价值。方法回顾性研究。纳入中山大学附属第一医院耳鼻咽喉科2015年5月—2019年10月经手术或活检病理证实的原发性面神经肿瘤患者16例,其中男11例、女5例,年龄15~56(34.9±11.7)岁。术前均行面部微小表面线圈局部高分辨3 T MR扫描及面神经曲面重建(方法A),同时行常规头线圈MR平扫及增强扫描(方法B)。(1)对比分析两种方法成像所显示的肿瘤的位置、累及范围、形态、生长方式以及信号特点的差异,采用配对t检验比较两种方法最大径测量值。(2)以反映肿瘤与面神经关系的特征性的面神经出入征阳性为面神经肿瘤的MRI诊断标准,以病理诊断为金标准,采用配对χ2检验比较两种MR扫描方法诊断面神经肿瘤的准确率。结果 (1)两种成像方法显示肿瘤位置、范围、形态一致,但与方法B相比,方法A肿瘤范围的显示更为直观。肿瘤位于左侧9例、右侧7例;所有肿瘤均累及面神经2节段及以上;肿瘤中心位于内听道处1例、迷路段1例、膝状神经节区6例、鼓室内5例、乳突区1例、腮腺区2例;形态表现为7例不规则形、表面分叶状或菜花状,5例呈类圆形,4例呈蘑菇形。(2)方法A测得肿瘤最大径为8 ~33.5 (18.9±7.9) mm,方法B为8.5 ~32.5(18.8±7.85) mm,两种方法差异无统计学意义(t=0.951,P>0.05)。(3)方法A肿瘤信号与面神经信号接近,有囊变者信号不均匀;方法B肿瘤T1WI以等信号、稍低信号为主,T2WI呈高信号、稍高信号,有囊变者信号不均匀。(4)本组16例患者采用方法A所得MRI显示面神经出入征均为阳性,方法B仅有4例面神经出入征呈现阳性,诊断准确率分别为16/16和4/16,差异有统计学意义(P=0.000)。结论使用微小表面线圈面神经高分辨MRI结合曲面重建技术可以更加清晰地显示肿瘤与面神经关系,提高原发性面神经肿瘤的诊断准确率;面神经出入征对原发性面神经肿瘤的MRI诊断具有重要价值。

Objective To investigate the clinical value of high-resolution MR scan using micro-surface coil in the diagnosis of primary facial nerve tumors.Methods Retrospective study.Sixteen cases of primary facial nerve tumors[11 males and 5 females,aged 15-56(34.9±11.7)years]confirmed by surgery or biopsy in the Department of Otorhinolaryngology,the First Affiliated Hospital of Sun Yat-sen University from May 2015 to October 2019 were collected.Before operation,all patients underwent facial high-resolution scan using micro-surface coil and curved planar reformation of facial nerves(Method A).Conventional MR plain and enhanced scans using head coil(Method B)were also performed.(1)The location,involved range,shape,growth pattern,and signal characteristics of tumors on images of these two methods were analyzed,and the maximum diameter was compared by paired t-test.(2)The characteristic"entering and exiting facial nerve sign",which reflected the relationship between tumors and facial nerves,was taken as the MRI diagnostic standard of facial nerve tumors,and pathological diagnosis was taken as the gold standard.The diagnostic accuracy of the two methods was compared by paired Chi-square test.Results(1)Methods A and B showed consistency in displaying the location,involved range,and shape of the tumors.However,compared with Method B,Method A displayed the range more intuitively.Nine tumors were located on the left side and seven on the right side.All tumors involved two or more segments of the facial nerve.The tumor center of 1 case was located in the internal auditory canal,1 in the labyrinthine segment,6 in the geniculate ganglion,5 in the tympanic cavity,1 in the mastoid region,and 2 in the parotid gland area.Seven cases showed irregular,lobulated,or cauliflower shape,5 showed round shape,and 4 showed mushroom shape.(2)The maximum diameter of tumors in Method A was 8-33.5(18.9±7.9)mm,and that in Method B was 8.5-32.5(18.8±7.85)mm.No significant difference was observed between the two methods(t=0.951,P>0.05).(3)In Method A,the signal of tumors was similar to that of normal nerves.In Method B,the tumors showed mainly or slight hypointensity on T1WI and hyperintensity or slight hyperintensity on T2WI.Tumors with cystic changes showed heterogeneous signal in both methods.(4)All 16 cases in Method A showed"entering and exiting facial nerve sign,"whereas only four cases showed this sign in Method B.The diagnostic accuracy was 16/16 and 4/16,respectively,and the difference between the two methods was statistically significant(P=0.000).Conclusions High-resolution MR imaging using micro-surface coil combined with curved planar reformation can improve the ability of showing the relationship between tumors and facial nerves,thereby improving the diagnostic accuracy of primary facial nerve tumors.The"entering and exiting facial nerve sign"is of great value to the MRI diagnosis.