182例鼻咽癌鼻窦侵犯的磁共振征象分析

MRI analysis of paranasal sinus invasion in 182 patients with nasopharyngeal carcinoma

目的分析182例鼻咽癌鼻窦侵犯的磁共振征象，提高对鼻咽癌鼻窦侵犯的MRI诊断认识。方法回顾性分析中山大学肿瘤防治中心2003年1月至2004年12月182例鼻咽癌鼻窦侵犯患者的磁共振资料。结果182例患者发生鼻窦侵犯，其中蝶窦侵犯的发生率最高。鼻咽癌鼻窦侵犯的主要磁共振征象包括：鼻窦窦壁破坏182例（100％）、鼻窦黏膜不均匀增厚174例（95．6％）、鼻窦腔内肿块与鼻咽原发肿瘤相连103例（56．6％），上述病灶T1WI平扫呈等或稍低信号，T2WI平扫呈等或稍高信号，增强扫描较明显不均匀强化，与鼻咽原发肿瘤的平扫信号和强化方式一致。141例（77．5％）合并鼻窦腔大量积液。T：加权序列鼻窦炎症增厚的黏膜和积液呈明显高信号，增强扫描炎症增厚的黏膜呈薄线样／环形强化；而窦腔肿瘤组织T2WI呈等或稍高信号，增强扫描明显不均匀强化。横断位T1平扫、T2平扫、T1增强扫描序列对于上颌窦、筛窦侵犯的检出率分别为88．4％、77．9％、96．5％和65．8％、73．7％、94．7％，T1增强扫描对于上颌窦、筛窦侵犯的检出率明显高于横断位T1、T2平扫（P〈0．05）；矢状位T1增强扫描可检出100％的蝶窦侵犯。结论MR多方位平扫及增强扫描能够提高鼻咽癌侵犯鼻窦的诊断率。鼻咽癌侵犯鼻窦的磁共振征象为：（1）鼻窦的窦壁破坏；（2）鼻窦的窦壁黏膜不均匀增厚；（3）鼻窦腔内肿块与鼻咽原发肿瘤相连，或伴有窦腔内大量积液。T2加权序列和增强扫描序列有助于鉴别鼻窦炎症和肿瘤侵犯。横断位T，增强扫描为显示上颌窦和筛窦侵犯的最佳序列，矢状位T1增强扫描为显示蝶窦侵犯的最佳序列。

Objective The aim of the study was to analyze the nuclear magnetic resonance image （MRI） findings for invasion of paranasal sinuses in patients with nasopharyngeal carcinoma （NPC） and to improve the understanding of its MRI diagnosis. Methods The MRI data of 182 patients with nasopharyngeal carcinoma and paranasal sinus invasion were retrospectively analyzed. Results One hundred and eigty-two patients developed paranasal sinus invasion, of which, the incidence of sphenoid sinus invasion was highest. The MRI findings of paranasal sinus invasion of patients with NPC were as follows： 100%, 95.6% and 56. 6% patients revealed damage of sinus wall, uneven thickening of mucosa, masses of the sinus cavity connected with the primary tumor of nasopharynx, and all the lesions presented iso- or slightly hypo-intense signal on T1 WI and iso- or slightly hyper-intense signal on T2WI and significantly heterogeneous enhancement after contrast administration, which were consistent with the primary tumor of the nasopharynx regarding to the signal intensity and reinforcement schedule. 77.5% patients presented massive sinus cavity effusion. T2-weighted images are excellent in differentiating high signal intensity thickened mucosa or retained secretions from relatively lower signal intensity tumor. In contrast-enhanced MRI, tumor with solid enhancement can be differentiated from thickened mucosa related to inflammation with a thin superficial enhancement. 96. 5% and 94. 7% patients with maxillary sinus invasion and ethmoid sinus invasion were detected with the contrast enhanced axial T1-weighted MR imaging respectively, which were higher than those with the non-enhanced axial T1 and T2 imaging （88.4% and 77. 9% for maxillary sinus invasion;65.8% and 73.7% for ethmoid sinus invasion）, the differences were statistically significant （P 〈 0.05 for all comparison）. All patients with sphenoid sinus invasion were detected with the contrast enhanced sagittal T^-weighted MR imaging. Conehlsion Muhiplanner MR scan and enhanced scan can improve the diagnosis of nvasion of paranasal sinuses in patients with NPC. The MRI findings of patients with NPC with paranasal sinus invasion include sinus wall damage ; unevenly thickening mucous membrane of sinuses ; tumors in sinus cavity connective with the primary tumor of nasopharynx , or with massive sinus cavity effusion. The T2- weighted sequence and contrast enhanced sequence are conducive to differential diagnosis of inflammatory changes from neoplastic tissues. The enhanced axial Tl-weighted section and the enhanced sagittal T1- weighted section are most helpful to detection of maxillary sinus, ethmoid sinus invasion and sphenoid sinus invasion, respectively.