鼻道、鼻咽恶性黑色素瘤的MRI诊断

目的 分析鼻道、鼻咽恶性黑色素瘤的MRI表现,探讨其诊断要点.方法 回顾性分析经病理证实的8例鼻道、鼻咽恶性黑色素瘤的MRI特征及临床资料,所有患者均行MR平扫、增强及动态增强检查.结果 肿瘤位于中鼻道1例,鼻咽部2例,鼻腔、上颌窦及同侧筛窦5例.5例可见明显骨质破坏并侵犯邻近结构,累及翼腭窝3例、颞下窝2例、眼眶4例、前颅底2例、咽旁间隙1例.MRI表现:3例直径＜2 cm,呈类圆形肿块,T1WI为高信号,T2 WI为低信号,呈明显均匀强化.5例直径＞3 cm,不规则肿块,MRI表现为混杂信号,T1WI以等、低信号为主,其内有斑片状高信号；在T2WI,1例以等低、信号为主,4例以稍高信号为主,增强扫描呈轻度不均匀强化.动态增强扫描时间-信号强度曲线平台型、流出型各4例.结论 鼻道、鼻咽恶性黑色素瘤MRI信号特征与肿瘤大小相关.肿瘤较小时T1WI呈高信号,T2WI呈低信号；肿瘤较大时MRI信号混杂,轻度不均匀强化为其特征.

MRI appearance of malignant melanoma in the sinonasal tract and nasopharynx

Objective To investigate the MRI appearance of malignant melanoma in the sinonasal tract and nasopharynx.Methods MRI Findings and clinical data from 8 patients with biopsy or operation proved malignant melanoma were retrospectively reviewed.Gadolinium-enhanced imaging and dynamic contrast enhancement scanning were performed in all cases.Results The majority of lesions were located in the nasopharynx (n =2),middle turbinate (n =1 ),or a combination of the nasal cavity,ethmoidal sinus,and maxillary sinus ( n =5 ).The aggressive nature of the tumors was demonstrated by bone destruction ( n =5 ) and invasion of adjacent structures,involving anterior fossa (n =2 ),orbits (n =4 ),infratemporal fossa ( n =2 ),pterygopalatine fossa ( n =3 ),and parapharyngeal space ( n =1 ).The MRI appearance included two patterns.In the first pattern,the tumors were round and small (smaller than 2 cm in maximum dimension in three patients).MR signal intensity of the lesions was hyperintense to gray matter on T1 WI and hypointense on T2.In the second pattern,the lesions were irregular and large ( larger than 3 cm in maximum dimension in five patients).They showed heterogeneous low-signal on T1 WI.On T2WI,one lesion showed isointensity or little hypo-intensity,and four lesions showed hyperintense.They demonstrated mild heterogeneous enhancement on gadolinium-enhanced images.Four patients demonstrated as plateau type time-signal intensity curve (TIC) pattern,and another four patients demonstrated as wash-out type TIC pattern.Conclusions The MR signal characteristic of the malignant melanoma in the sinonasal tract and nasopharynx were related with the tumor size.When the lesion was small,the MR signal intensity was more typical.When the lesion was large,they had mixed signal intensity as other malignant tumors,and specific mild heterogeneous enhancement.