鼻腔鼻窦原发恶性黑色素瘤MRI表现及信号分型

MRI features and signal pattern of primary sinonasal malignant melanomas

目的探讨鼻腔鼻窦原发恶性黑色素瘤(SMM)的MRI表现,并提出T1WI和T2WI信号分型方法,以期提高诊断准确率。方法回顾性分析2007年4月至2018年11月首都医科大学附属北京同仁医院经手术或活检病理证实的63例SMM的MRI表现,并根据肿瘤最大层面内T1WI和T2WI不同信号面积所占比例分为Ⅰ~Ⅳ型。T1WI信号分型标准:Ⅰ型,肿瘤内高信号面积≥50%;Ⅱ型,肿瘤内高信号面积<50%;Ⅲ型,肿瘤不含高信号,等信号区域面积≥50%;Ⅳ型,肿瘤不含高信号,低信号面积≥50%。T2WI信号分型:Ⅰ型,肿瘤内低信号面积≥50%;Ⅱ型,肿瘤内低信号面积<50%;Ⅲ型,肿瘤不含低信号,等信号面积≥50%;Ⅳ型,肿瘤不含低信号,高信号面积≥50%。统计各型所占比例。结果SMM T1WI信号分型:Ⅰ型27例(42.9%,27/63)、Ⅱ型25例(39.7%,25/63)、Ⅲ型4例(6.3%,4/63)、Ⅳ型7例(11.1%,7/63);T2WI信号表现:Ⅰ型29例(46.0%,29/63)、Ⅱ型28例(44.4%,28/63)、Ⅲ型2例(3.3%,2/63)、Ⅳ型4例(6.3%,4/63)。其中T1WI和T2WI均为Ⅰ型的16例。结论MRI信号分型能区分典型和不典型SMM,典型SMM T1WI和T2WI均表现为Ⅰ型信号,容易诊断,但所占比例不到1/2;对不典型SMM,肿瘤T1WI上如有高信号或T2WI上有低信号,都应考虑有黑色素瘤的可能。

Objective To investigate the MRI features of the primary sinonasal malignant melanoma(SMM)and evaluate the signal pattern based on T1WI and T2WI,in order to improve the diagnostic accuracy of SMM.Methods The MRI findings of 63 SMM cases confirmed by pathology from April 2007 to November 2018 at Beijing Tongren Hospital,Capital Medical University were analyzed retrospectively.The signal intensity of malignant melanoma was classified into four types(Ⅰ—Ⅳ)according to the proportion of signal areas of the largest slice of the tumor on T1WI and T2WI.The classification criteria according to T1WI:typeⅠ,the area of hyperintensity was≥50%;typeⅡ,the area of hyperintensity was<50%;typeⅢ,the tumor did not show hyperintensity,and the area of isointensity was≥50%;typeⅣ,the tumor did not have high signal area,and the area of low signal was≥50%.The classification criteria according to T2WI:typeⅠ,the area of low signal in the tumor was≥50%;typeⅡ,the area of low signal was<50%;typeⅢ,the tumor did not contain low signal area,and the area of isointensity was≥50%;typeⅣ,the tumor did not have low signal area,and the area of high signal intensity was≥50%.The proportion of each type was calculated.Results According to T1WI,typeⅠwas identified in 27 cases(42.9%,27/63),typeⅡin 25 cases(39.7%,25/63),typeⅢin 4 cases(6.3%,4/63),and typeⅣin 7 cases(11.1%,7/63).According to T2WI,typeⅠwas demonstrated in 29 cases(46.0%,29/63),typeⅡin 28 cases(44.4%,28/63),typeⅢin 2 cases(3.3%,2/63),and typeⅣin 4 cases(6.3%,4/63).There were 16 cases classified as type I based on T1WI and T2WI.Conclusions Typical and atypical SMM can be identified according to signal patterns.The typeⅠsignal pattern of SMM cases on T1WI and T2WI is typical and can be easily diagnosed,but the proportion was less than 50%.For atypical SMM,malignant melanoma should be strongly suspected if hyperintense on T1WI or hypointense on T2WI is found.