MRI features and signal pattern of primary sinonasal malignant melanomas / 中华放射学杂志

ABSTRACT

Objective:To investigate the MRI features of the primary sinonasal malignant melanoma (SMM) and evaluate the signal pattern based on T 1WI and T 2WI, 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 T 1WI and T 2WI. The classification criteria according to T 1WI: type Ⅰ, the area of hyperintensity was ≥50%; type Ⅱ, the area of hyperintensity was <50%; type Ⅲ, the tumor did not show hyperintensity, and the area of isointensity was ≥50%; type Ⅳ, the tumor did not have high signal area, and the area of low signal was ≥50%. The classification criteria according to T 2WI: type Ⅰ, the area of low signal in the tumor was ≥50%; type Ⅱ, the area of low signal was <50%; type Ⅲ, the tumor did not contain low signal area, and the area of isointensity was ≥50%; type Ⅳ, 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 T 1WI, typeⅠwas identified in 27 cases (42.9%, 27/63), typeⅡ in 25 cases (39.7%, 25/63), type Ⅲ in 4 cases (6.3%, 4/63), and type Ⅳ in 7 cases (11.1%, 7/63). According to T 2WI, type Ⅰwas demonstrated in 29 cases (46.0%, 29/63), type Ⅱ in 28 cases (44.4%, 28/63), type Ⅲ in 2 cases (3.3%, 2/63), and type Ⅳ in 4 cases (6.3%, 4/63). There were 16 cases classified as type I based on T 1WI and T 2WI. Conclusions:Typical and atypical SMM can be identified according to signal patterns. The typeⅠsignal pattern of SMM cases on T 1WI and T 2WI 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 T 1WI or hypointense on T 2WI is found.