翼腭窝原发肿瘤的CT和MRI诊断

目的 探讨翼腭窝原发肿瘤的CT和MRI表现，提高其诊断准确性。方法 回顾性分析11例经手术病理证实的翼腭窝原发肿瘤的影像资料。结果 11例肿瘤均起源翼腭窝，通过其自然通道向邻近结构不同程度生长，其中神经鞘瘤3例、神经纤维瘤2例、血管纤维瘤3例、腺样囊性癌2例、黑色素瘤1例。神经源性肿瘤边界清楚，高分辨率CT(HRCT)可见翼腭窝扩大，周边骨质受压移位、变薄；在MR T1WI呈等信号(与脑实质比较)，T2WI呈高信号，2例神经纤维瘤信号均匀，呈均匀强化。3例神经鞘瘤可见囊性区，呈不均匀强化。血管纤维瘤边界较清楚，HRCT可见翼腭窝扩大，周边骨质受压移位，变薄及破坏。在MR T1WI呈等信号(与肌肉比较)2例，低信号1例；T2WI呈高信号，明显强化，1例瘤体可见散在点或条状流空信号，呈不均匀强化。腺样囊性癌边界不清楚，形态不规整，HRCT示翼腭窝扩大，骨质呈虫蚀样破坏；在MR T1WI呈低信号(与肌肉比较)，T2WI呈高信号，信号不均，瘤体内可见点、囊状更高信号，呈不均匀强化。黑色素瘤边界清楚，形态不规整，HRCT示翼腭窝扩大，前侧骨质受压移位、变薄，其余骨壁破坏，肿瘤突人邻近结构；MR T1WI呈稍高信号(与肌肉比较)，T2WI呈高信号，见多发点或条状流空信号，呈不均匀强化。结论 CT能清楚显示翼腭窝周边骨质改变，MRI能准确显示病变范围。两者结合能较准确地对神经源性肿瘤及血管纤维瘤作出定性诊断；为临床制定治疗方案、确定手术入路及评价治疗效果提供依据。

CT and MRI diagnosis of tumor originating in the pterygopalatine fossa

Objective To investigate the CT and MRI findings of tumors originating in the pterygopalatine fossa so as to promote the diagnostic accuracy. Methods All 11 patients with tumors arising from the pterygopalatine fossa were confirmed by pathology and surgery. CT and MRI appearances were analyzed retrospectively. Results The tumors included 3 neurilemmomas, 2 neurofibromas, 3 angiofibromas, 2 adenoid cystic carcinomas, and 1 melanoma, and they all extended through communicating pathways of the pterygopalatine fossa. On HRCT, neurogenic tumors caused enlargement of the pterygopalatine fossa with thinning of their bony walls, while MRI demonstrated isointense signal to brain on T 1WI and hyperintense signal on T 2WI. Two neurofibromas showed homogeneous enhancement after administration of contrast medium while 3 neurilemmomas showed heterogeneous enhancement. On HRCT scans, angiofibroma caused enlargement of the pterygopalatine fossa, eroding their bony walls. On MR imaging, the lesions were isointense compared to muscle on T 1WI, hyperintense on T 2WI with marked postcontrast enhancement. One case of angiofibroma showed scattered stippling or stria-shaped signal voids and inhomogeneous postcontrast enhancement. On CT scans, adenoid cystic carcinoma revealed moth-eaten bony wall of the pterygopalatine fossa with poorly defined margins and irregular shapes. Adenoid cystic carcinoma showed hypointense signal compared to muscle on T 1WI, inhomogeneous hyperintense signal on T 2WI and heterogeneous postcontrast enhancement. One case of melanoma showed enlargement of pterygopalatine fossa and destruction of the bony walls except for the anterior wall by invading adjacent structures with well-defined border and irregular shape. On MR imaging, the lesion showed isointense signal compared to muscle on T 1WI and hyperintense signal on T 2WI with discrete mottled or linear signal voids and inhomogeneous postcontrast enhancement. Conclusion HRCT can depict bony changes clearly and MRI can demonstrate optimally the extent of the lesion in pterygopalatine fossa. Both imaging modalities can contribute to the diagnosis of neurogenic tumor and angiofibroma and can provide information for therapeutic procedure and surgical planning.