咽旁间隙多形性腺瘤与神经源性肿瘤的MRI鉴别诊断

目的探讨咽旁间隙多形性腺瘤与神经源性肿瘤的MRI表现,提高对两者的鉴别诊断水平。材料与方法回顾性分析经手术病理证实的10例咽旁间隙多形性腺瘤及18例神经源性肿瘤的MRI表现。结果除1例有双侧迷走神经副神经节瘤外,其余均为单发。10例多形性腺瘤均位于茎突前间隙,使同侧茎突及其肌群、腭帆张肌、二腹肌及颈内动、静脉受压向后移位。17例神经源性肿瘤(1例颈静脉球瘤除外)均位于茎突后间隙,肿块与腮腺深叶分界清楚,同侧咽旁脂肪组织、茎突及其肌群、腭帆张肌、二腹肌及颈内动脉受压向前移位。其中4例神经鞘瘤、3例迷走神经副神经节瘤和1例神经纤维瘤使同侧颈内动、静脉明显分离;3例颈动脉体瘤使颈内、外动脉明显分离。另外,4例多形性腺瘤(40%)在MRI上可见局灶性低信号,即"靶征"。7例副神经节瘤(88%)可呈典型的"盐和胡椒征"。结论通过MRI仔细观察咽旁间隙邻近结构的移位情况,判断肿瘤发生的精确位置并结合肿瘤的特征性信号,从而有助于提高对两者的鉴别诊断水平。

MRI Differential Diagnosis of Pleomorphic Adenomas and Neurogenic Tumors in the Parapharyngeal Space

Objective To analyze the MRI appearance of pleomorphic adenomas and neurogenlc rumors in the parapharyngeal space （PPS）, and to improve the differential diagnosis between them.Materials and Methods Ten cases of pleomorphic adenomas and 18 cases ofneurogenic tumors in the PPS were collected in the study. The lesion,s position, the displacement with the surrounding structures, number, shape, border, uniformity, characteristic signal, enhancement degree and capsule were analyzed retrospectively. All of them were scanned with MRI and then confirmed pathologically. Results The rest were single lesions except 1 vagal glomus tumor had two lesions on both tides of the neck. 10 pleomorphic adenomas were located in the prestyloid compartment and the prestyloid PPS fat： the styloid process and its muscles; tensor veli palatine, digastric muscle and the carotid sheath were compressed and displaced posteriorly. On the contrary, 18 neurogenic tumors which were located in the retrostyloid compartment made these structures anterior displacement. Moreover, 4 schwannomas, 3 vagal glomus tumors and 1 neurofibroma made the ICA （internal carotid artery） and the IJV （internal jugular vein） separation. 3 carotid body tumors Made the ICA and the ECA （external carotid artery） separation. There were clear boundaries and visible fat space between neurogenic tumors and deep-lobe of parotid gland. Diagnostic features, such as ＂patchy or actiniform＂ low signal intensity areas in some （4/10） pleomorphic adenomas, and ＂salt-and-pepper＂ appearance in most （7/8） paragangliomas, were found on MRI. Condlusion Through the MRI careful observation the displacement with the surrounding structures in the PPS, judge the precise location of the tumor and combined with characteristic signal of the tumor, which helps to improve the differential diagnosis level.