鼻腔及鼻窦原发性恶性黑色素瘤CT和MRI的诊断价值

The diagnostic value of MRI and CT in primary malignant melanoma of the nasal cavity and nasal sinuses

目的探讨CT和MR诊断鼻腔及鼻窦原发性恶性黑色素瘤的影像特点。方法回顾性分析经病理证实的11例鼻腔及鼻窦原发恶性黑色素瘤的CT和MRI影像表现。本组11例病变短径均>1.5cm,CT检查11例,11例均行CT平扫;MRI扫描9例,均行平扫+DWI+增强扫描。重点观察病灶的数目、位置、形态、对周围结构侵犯及影像学特征。结果11例中,CT、MRI能准确反映病灶的位置、形态及邻近结构的累及情况。CT表现为单侧5例,双侧6例;肿瘤形态不规则,呈软组织密度,其内未见钙化及囊变,11例均侵犯周围组织;11例均有周围骨质破坏;9例患者主要MRI表现为9例形态均不规则;单侧5例,双侧4例;表现为混杂信号,T_1WI以等、低信号为主,其内可见斑片状高信号;T_2WI 5例以等低信号为主,4例以稍高信号为主,DWI均呈高信号,增强扫描呈轻中度不均匀强化,邻近周围组织均有侵犯。结论鼻腔及鼻窦原发性恶性黑色素瘤CT表现无特异性;MRI表现具有一定特异性。CT和MRI能很好地显示肿瘤的部位、与周围组织关系及邻近骨质破坏情况,为临床分期及手术方案制定提供帮助。

Objective To investigate the imaging fandings of computed tomography （CT） and magnetic resonance imaging （MRI） for primary malignant melanomas arising from nasal cavity and paranasal sinuses. Methods CT and MRI findins of eleven cases of pathologically confimed primary malignant melanoma located in nasal cavity and paranasal sinuses were retrospectively analyzed. The short diameter of all the lesions was larger than 1.5 cm, eleven patients underwent CT plain scan, nine patients were performed MRI scan including routine MR scan, diffusion-weighted imaging and contrast-enhanced MRI. Results CT, MRI can accurately reflect the location, morphology and the involvement of the adjacent structures. Among eleven patients under going CT examination, five were unilateral and six bilateral. All CT findings showed that eight cases were irregular shape, soft tissue density, but no calcification and cystic degeneration. And all the eleven lesions demonstrated invasiveness to the surrounding tis- sue and destruction of the adjacent bone structure. Among the eleven patients with MRI examination, five were unilateral and four bilateral; All MRI findings showed that the eleven cases were also irregularly shaped; five were unilateral and four bilateral. They showed heterogeneous low-signal on Tj WI. On T2WI, five lesion showed isointensity or little hypo-intensity, and four lesions showed hyperintense. All the eleven cases showed high signal on DWI. They demonstrated mild heterogeneous enhancement on gadolinium-enhanced images. The eleven lesions also showed invasiveness to the smTaunding tissues. Conclusion Primary malignant melanoma of nasal cavity and paranasal sinuses is not specific on CT imaging, but sometimes can display typical signs on MR imaging. CT, especially MRI appearances can localize the tumars, and delineate the relationship of the lesions with the surrounding tissue, provide help for clinical staging and surgical planning.