鼻咽后部筋膜间隙MRI表现

MRI features of retronasopharyngeal space

目的探讨MR显示鼻咽后部筋膜间隙组织结构的价值。方法对20名健康志愿者行鼻咽部MRT1W及轴位高分辨T2W平扫,观察鼻咽后部筋膜间隙的MRI表现。选取以甲醛溶液固定的成年人标本5具,采集头颈部MRI,再冷冻后制成横切面标本,将咽后软组织部分进行组织切片、HE染色,对照观察鼻咽后部筋膜间隙的MRI及镜下表现。结果鼻咽上份层面鼻咽后部组织从前向后均可见黏膜、咽颅底筋膜、椎前肌及枕骨斜坡,椎前肌内信号不均匀,后缘与枕骨后基底部及斜坡上份分界无法清晰分辨,前缘光滑并可见连续清晰低信号筋膜;标本对应层面镜下表现为咽颅底筋膜、颊咽筋膜、翼状筋膜及椎前筋膜所构成的筋膜层。鼻咽下份层面椎前肌信号均匀,后缘与骨质间隙内见连续的高信号脂肪层,前缘光滑但筋膜不能完整清晰显示;标本对应层面镜下为咽缩肌前缘纤维膜明显变薄,系咽缩肌将其与后方筋膜(颊咽筋膜、翼状筋膜及椎前筋膜)分开所致。结论MRI可清晰显示鼻咽后部筋膜层、椎前肌及脂肪间隙结构。

Objective To investigate the value of MRI in displaying posterior wall of nasopharynx.Methods Plain MR scanning were performed in volunteers without head and neck lesions,including axial T1W and high-resolution T2W,and MRI manifestations of the posterior wall of nasopharynx were observed.Five formalin-fixed head and neck of adult cadavers were first evaluated with MRI,and then were frozen,cut into cross-section and stained with HE.The manifestations of the posterior wall of nasopharynx were observed contrastively with MRI and microscopic examination.Results At the upper level of nasopharynx,the posterior wall of nasopharynx consisted of nasopharyngeal mucosa,fascia,prevertebral muscle and clivus from the outside.The heterogeneous signal was detected in bilateral prevertebral muscle,which was unable to clearly distinguish the posterior boundary of bilateral prevertebral muscles from the basilar clivus.Bilateral anterior edge of the prevertebral muscle was smooth and continuous low signal fascia shadow by gross observation,which was the fascia layer that consisted of the pharyngobasilar fascia,buccopharyngeal fascia,alar fascia and prevertebral fascia at the microscopic level.At the lower 1/2 level of nasopharynx,homogeneous signal was detected in bilateral prevertebral muscles,and the anterior edge was smooth while the shadow of the fascia was ambiguous,where the fibrous membranes of the pharyngeal constrictor turned thin distinctly and the pharyngeal constrictor separated it from the posterior fascia(consisted of buccopharyngeal fascia,alar fascia and prevertebral fascia)at the microscopic level.Furthermore,there was a high signal of the fat strip between posterior edge of bilateral prevertebral muscles and the lower clivus.Conclusion MRI can clearly show the structures of fascia,prevertebral muscles and fat space in the posterior wall of nasopharynx.