螺旋CT三维重建咽旁隙的研究

Threedimensional reconstruction of parapharyngeal space by spiral CT

摘要:

目的探索螺旋CT扫描成人呈张口位时咽旁隙成像并行多平面重建和三维重建等后处理，为经口入路切除咽旁隙肿瘤提供解剖依据及术前指导。方法选择咽旁隙无占位性病变患者28例，放置张口器后行多层螺旋CT血管成像，应用多平面重建测量茎突长度并统计茎突末端与第一颈椎横突的关系，于颅底层面测量茎突至颈内动脉、下颌骨升支后缘的距离并进行统计学分析。利用容积重现和剪切技术对图像进行三维重建等后处理，观察颈内动静脉走行及是否存在变异移位等。结果茎突长度、茎突根部至颈内动脉、茎突根部至下颌骨升支后缘的平均距离分别为(2.50±0.80)、(1.09±0.26)、(2.27±0.29)cm，侧别、性别方面均无显著性差异（P＞0.05）。78.6%（44/56）茎突末端位于第一颈椎横突或以下，64.3%（36/56）颈内动脉起始部位低于舌骨，12.5%（7/56）咽旁隙段颈内静脉先走行于颈内动脉前方然后再转向后外。结论咽旁隙以茎突至毗邻解剖结构的距离为参考，有助于神经血管的定位。三维重建的图像能清晰地显示颅底、下颌骨升支、茎突、颈内动静脉等咽旁隙周边及内部结构。咽旁隙段颈内动静脉均存在一定的变异率，为模拟手术入路和术中颈内动脉定位提供重要信息。

关键词:咽旁隙|经口入路|三维重建|容积再现

Abstract:

ObjectiveTo provide anatomical basis and preoperative guidance for removal of parapharyngeal space tumors via a transoral approach by multiplanar and threedimensional (3D) reconstructions with spiral CT scanning in healthy subjects with "mouth open" position.MethodsMultislice spiral CT angiography was performed on 28 adults without parapharyngeal spaceoccupying lesions in "mouth open" position. By multiplanar reconstruction, the length of styloid process and the relationship between the end of styloid process and the transverse process of the first cervical vertebra were detected. At the skull base level, the distance between the styloid process and the posterior boarder of the mandibular ramus, and that from the styloid process to the internal carotid artery were measured and statistically analyzed. Volume reconstruction technique and shear technique were used to conduct 3D reconstruction of the images to observe the courses of internal carotid artery and internal jugular and their variation and displacement.ResultsThe average length of the styloid process, the distance from styloid process to the internal carotid artery, and that between styloid process root and mandibular ramus were (2.50±0.80) cm, (1.09±0.26) cm, and (2.27±0.29) cm respectively. The differences of above parameters between different genders and those between different sides were all statistically insignificant (all P>0.05). Of them, about 78.6%(44/56) of the ends of the styloid process were located at or below the transverse process of the first cervical vertebra. The internal carotid artery in 64.3%(36/56) of the subjects branched at the beginning of the lower part of the hyoid bone. The internal jugular vein preceded in front of the internal carotid artery and then turned to the posterior in 12.5%(7/56) of the subjects.ConclusionsThe distances between the styloid process and other anatomical structures of the parapharyngeal space can be used as references for the localization of nerves and blood vessels. 3D reconstruction of the image can clearly show the skull base, mandibular ramus, styloid process, carotid artery, internal jugular vein and other structures of the parapharyngeal space. There is a certain variation rate in internal carotid artery and jugular vein, which provides important information for choosing a surgical approach and positioning the internal carotid artery during surgery.

Key words:Parapharyngeal space|Oral approach|Threedimensional reconstruction|Volume rendering