Differentiation between intraspinal schwannoma and meningioma by MR characteristics and clinic features.

OBJECTIVES: To retrospectively review the MRI characteristics and clinic features and evaluate the effectiveness of MR imaging in differentiating intraspinal schwannomas and meningiomas, with the excised histopathologic findings as the reference standard. MATERIALS AND METHODS: One hundred and four schwannomas (M/F, 57:47) and 53 meningiomas (M/F, 13:40) underwent MR examinations before surgical treatment. Simple clinic data and imaging findings were considered:(a) location (craniocaudal and axial), (b) size, (c) morphology, (d) dural contact, (e) signal characteristics, (f) enhancement degree and patterns. The usefulness of the algorithm for differential diagnosis was examined between the two tumors. RESULTS: Interobserver agreement was good (κ = 0.7-0.9). Ten cases meningiomas demonstrated multiple lesions. There was a female predominance in the meningiomas (P < 0.001). Meningiomas predominantly were located in the ventral or anterolateral areas of thoracic regions, while schwannomas in the posterolateral areas of the thoracic and the lumbar regions (P < 0.001). Mean size of the lesions was 1.47 ± 0.36 cm for meningioma, and 2.02 ± 1.13 cm for schwannoma (P < 0.001). A dumbbell shape with intervertebral foramen widening could detect schwannomas, while the "dural tail sign" did meningiomas (P < 0.001). Hypointense and miscellaneous signal implied meningioma on T1WIs (P < 0.001). Isointense was more frequently observed in the meningiomas, while the fluid signal intensity and miscellaneous signal in the schwannomas on T2WIs (P < 0.001). Schwannomas usually manifested rim enhancement, while meningiomas diffuse enhancement (P = 0.005). There were six variables including the logistic equation (age, size, dural tail sign, morphology, T2WI, and axial location). The accuracy of the algorithm in diagnosis of schwannomas was 87.1%. CONCLUSIONS: Combination of clinic data and MRI performs significantly for differentiating between intraspinal meningiomas and schwannomas.