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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.
RESUMO
Objective:To compare MRI findings of uveal melanomas and other intraocular masses in adults and to evaluate the optimal MRI features for the differential diagnosis.Methods:The MRI data of 254 patients with intraocular masses confirmed by histopathologic or clinical follow-up results from March 2005 to December 2015 in Beijing Tongren Hospital, Capital Medical University was analyzed retrospectively. A total of 128 patients with uveal melanoma and 126 patients with other intraocular masses were enrolled. MRI findings of the masses including the location, shape, margin, signal intensity on T 1WI and T 2WI compared to the gray matter and vitreous body, homogeneity and degree of enhancement of the mass, secondary retinal detachment, height, and ratio of basal diameter to height were compared between uveal melanoma and other intraocular masses by χ 2 test or independent t test. The logistic regression analysis was performed to identify the most discriminating MRI features. The diagnostic performance of different predictive models was analyzed by receiver operating characteristic (ROC) curve. The model of multiple parameters was established by logistic analysis, and the diagnostic efficacy was evaluated. Results:The location, shape, margin, signal intensity on T 1WI and T 2WI compared to the gray matter and vitreous body, homogeneity and degree of enhancement of the mass, secondary retinal detachment, height and ratio of basal diameter to height were significantly different between the uveal melanoma and other intraocular masses (all P<0.05). The results of logistic regression analysis showed that the signal intensity on T 1WI and T 2WI compared to the gray matter, height, shape, location, degree of enhancement of the mass, and secondary retinal detachment were associated with higher likelihood of uveal melanoma. The mass with hypointense on T 2WI (compared with gray matter) was the best MRI feature in the differential diagnosis of uveal melanoma and other intraocular masses (odds ratio 12.237), with the accuracy of 86.2%. The diagnostic accuracy of low signal on T 2WI and high signal on T 1WI (compared with gray matter) was significantly higher than those of vitreous (Delong test, P<0.001). The sensitivity, specificity and accuracy of the combination of height, degree of enhancement, T 1WI and T 2WI signal compared to the gray matter were 90.6%, 92.1% and 96.1%, respectively. The diagnostic performance of combination features was higher than that of each single sign ( P<0.001). Conclusion:MRI features including the signal intensity on T 1WI and T 2WI compared to the gray matter, height, shape, degree of enhancement of the mass, and secondary retinal detachment are helpful in the differential diagnosis between uveal melanoma and other intraocular masses. In addition, the gray matter as the reference is superior to the vitreous body in the evaluation of the signal intensity of intraocular masses.