鼻咽缝间隙的解剖学基础及其影像学表现和意义

目的 在影像上提出鼻咽缝间隙的概念，介绍其CT和MRI表现及其意义。方法 正常CT组43例，正常MRI组36例，均进行鼻咽轴面平扫，其中加做鼻咽冠状面CT和MR扫描各5例，7例加做鼻咽后壁矢状面MR薄层扫描；2例鼻咽轴位断面标本作对照；鼻咽癌（NPC）组30例，同时进行CT与MR扫描，对鼻咽后软组织结构影像学表现进行详细观察分析。结果 鼻咽缝间隙位于椎前并列的头长肌或颈长肌之间，咽后壁后方，枕骨及颈椎前方，它包括上述肌肉之间的咽缝、咽后间隙、危险间隙、椎前间隙部分和组成这些间隙的筋膜，以及其中的纤维结缔组织、脂肪和淋巴结等结构，在CT上表现为三角形不均匀低密度影，在MRI上，呈三角形不均匀高信号影，其正中有粗细不一的低信号咽缝。正常CT组43例均在椎前肌之间出现1个层面以上的、呈低密度的两侧对称的三角形影，为鼻咽缝间隙；在斜坡和硬腭水平之间均见鼻咽缝间隙者22例，部分层面显示鼻咽缝间隙者14例，鼻咽缝间隙达口咽水平者7例。正常MRI组36例，在轴面像上35例在椎前肌之间可见两侧对称的呈不均匀高信号的三角形鼻咽缝间隙；从斜坡至硬腭水平均见鼻咽缝间隙者13例，部分可见11例，鼻咽缝间隙达口咽水平者11例；矢状面像上，鼻咽缝间隙止于C2椎体上部者4例、下部者3例；冠状面像上，鼻咽缝间隙呈纵行条带状影2例，倒置梯形3例。2具鼻咽断面尸体标本均见鼻咽后壁后方并列的头长肌或颈长肌之间三角形疏松纤维结缔组织。NPC组30例中鼻咽缝间隙对称存在者14例，不对称性变窄1例，消失者15例。结论 鼻咽部椎前并列的头长肌或颈长肌之间的结构在CT和MRI上统称为鼻咽缝间隙是合适的；NPC患者的鼻咽缝间隙消失和不对称性变窄多提示肿瘤侵犯椎前肌，而对称存在时，肿瘤多位于鼻咽顶后壁浅层。

Anatomic basis, imaging findings and significance of nasopharynx raphe space

Objective To advance the conception of nasopharynx raphe space (NRS) on imaging, and to introduce its CT and MR appearances as well as significance. Methods Nasopharyngeal axial plain scans were performed in 43 cases of normal CT group and 36 cases of normal MRI group, nasopharyngeal coronal CT and MR scans in 5 cases of the CT group and 5 cases of MR group, and nasopharyngeal posterior wall thin slice sagittal MR scans in 7 cases of the MRI group. Two cases of axial nasopharynx specimens were used for comparison. CT and MR scans were performed in 30 patients with proven nasopharyngeal carcinoma (NPC). Then, imaging findings of retro nasopharyngeal soft tissue were observed and analyzed in detail. Results NRS was between two longus capitis muscle or longus coli muscle, rear of pharyngeal posterior wall, and in front of occipital bone and cervical vertebrae.NRS included part of nasopharynx raphe, retro pharyngeal space, danger space, prevertebral space, and the fascia of these spaces, as well as with the fibrous connective tissue, fat, and lymph nodes and so on. On CT, NRS displayed as triangular inhomogeneous low density, in midline of which showed isopyknic thick or thin line named nasopharynx raphe and occasionally showed obscurity. Nasopharynx raphe divided NRS into symmetric two halves. On MRI, NRS displayed as triangular inhomogeneous high signal intensity and various thickness of low signal intensity in the midline called nasopharynx raphe. NRS could be displayed in the level between clivus and palatum durum in most cases and extended down to pharynx level in some individual. On coronal images, NRS could be displayed as longitudinal strip or inverse trapezoidal shape. In 30 cases with NPC, symmetry of NRS was displayed in 14 cases, in which 1 case showed involvement of prevertebral muscles. Asymmetrical narrowing or disappearing of NRS was detected in 16 cases, in which 14 cases showed involvement of prevertebral muscles. Conclusion It is suitable that the structures between two longus capitis muscle or longus coli muscle are called NRS on CT and MRI.