Abstract
ObjectivesTo retrospectively determine the diagnostic ability of MRI in differentiating between intradural extramedullary spinal schwannomas and meningiomas.MethodsA total of 199 patients with spinal intradural extramedullary tumors who underwent preoperative contrast-enhanced MRI between January 2012 and December 2018 were included in this study. Two radiologists independently analyzed the presence of cystic change, dural tail sign, and neural foraminal extension. Clinical and MRI features between the two groups were compared by univariable and multivariable analyses using logistic regression. Interobserver agreements were calculated using kappa statistics.ResultsPatients with schwannoma showed significantly higher frequency of cystic change (96% vs 24%, P < 0.001), neural foraminal extension (29% vs 3%, P = 0.001), and lumbar location (41% vs 5%, P = 0.008). Patients with meningioma showed significantly higher frequency of dural tail sign (64% vs 1%, P < 0.001), thoracic location (75% vs 31%, P = 0.007), older age (59.7 years vs 47.6 years, P < 0.001), higher female predominance (83% vs 50%, P < 0.001), and smaller size (19.8 cm vs 28.8 cm, P < 0.001). Multivariable analysis showed that cystic change (P < 0.001; odds ratio [OR], 0.02), dural tail sign (P < 0.001; OR, 36.23), age (P = 0.032; OR, 1.06), and lumbar location (P = 0.006; OR, 0.02) were independent factors. Interobserver agreements were almost perfect for all analyses.ConclusionsMRI features were useful in differentiating between intradural extramedullary schwannomas from meningiomas. The presence of cystic change and dural tail sign were independently significant discriminators.
Highlights
Multivariable analysis showed that cystic change (P < 0.001; odds ratio [OR], 0.02), dural tail sign (P < 0.001; OR, 36.23), age (P = 0.032; OR, 1.06), and lumbar location (P = 0.006; OR, 0.02) were independent factors
Magnetic resonance imaging (MRI) features were useful in differentiating between intradural extramedullary schwannomas from meningiomas
Intradural extramedullary spinal tumors are the most common type of spinal tumors that may result in serious morbidity related to progressive neurologic deficits. [1,2,3] Among them, meningiomas and schwannomas are the two most common histologic subtypes, which comprise 55–90% of all intradural extramedullary spinal tumors. [4,5] both tumors are mostly benign, there is a substantial difference between the surgical techniques for removing each. [6,7] Since spinal meningiomas have a tendency to recur, complete tumor resection with dural excision is recommended whenever practicable to lower the recurrence rate. [6,8,9] radiologic differentiation between these two spinal tumors is a crucial step in surgical planning
Summary
Intradural extramedullary spinal tumors are the most common type of spinal tumors that may result in serious morbidity related to progressive neurologic deficits. [1,2,3] Among them, meningiomas and schwannomas are the two most common histologic subtypes, which comprise 55–90% of all intradural extramedullary spinal tumors. [4,5] both tumors are mostly benign, there is a substantial difference between the surgical techniques for removing each. [6,7] Since spinal meningiomas have a tendency to recur, complete tumor resection with dural excision is recommended whenever practicable to lower the recurrence rate. [6,8,9] radiologic differentiation between these two spinal tumors is a crucial step in surgical planning.Magnetic resonance imaging (MRI) serves a critical role in evaluating patients suspected to have spinal tumors by detecting and characterizing the lesions. [10,11,12] Many studies have reported MRI to be useful in differentiating between intradural extramedullary schwannomas and meningiomas. [1,7,13,14] Besides locating the tumor, dural tail sign or neural foraminal extension was suggested as a useful imaging feature in differentiating between the two histologic subtypes. [4,7,13,14] Signal intensity of the tumor on T2-weighted image was shown to be helpful for the differentiation; schwannomas have a tendency to show a hyperintense signal while a substantial portion of meningiomas shows an isointense signal compared to that of the spinal cord. [7,13,14] most of the reported studies involve few cases, and the discriminating ability of each sign varies among studies. [1,4,7,13,14] there is room for further investigation to identify other and better imaging features that could help in differentiating between subtypes of intradural extramedullary spinal tumors.Schwannomas are histologically characterized by the presence of alternating areas with two distinct spindle cell arrangements; Antoni A region, a highly cellular area, and Antoni B region, which is a loosely organized myxoid tissue. [15,16] Cells within the Antoni B regions are often separated from one another by microcysts filled with mucin. [17] It was suggested that these microcysts could coalesce to form macrocyst, which can be detected on MRI. [15,18] In addition, vascularization of Antoni B region is reported to contain degenerative features, and further degeneration in this region can form larger cyst. [15] A heterogeneous high signal with immeasurably small foci of fluid signal within the tumor demonstrated on a T2-weighted image was reported to represent histopathological cyst formation. [14,19] We assumed that the heterogeneous high T2 signal and large cyst formation within the tumor are part of a continuum with different levels of degeneration, which may represent histological microcyst and macrocyst formation, respectively. [1,2,3] Among them, meningiomas and schwannomas are the two most common histologic subtypes, which comprise 55–90% of all intradural extramedullary spinal tumors. [10,11,12] Many studies have reported MRI to be useful in differentiating between intradural extramedullary schwannomas and meningiomas. [1,4,7,13,14] there is room for further investigation to identify other and better imaging features that could help in differentiating between subtypes of intradural extramedullary spinal tumors. We hypothesized that the presence of cystic change on T2-weighted image can help in differentiating between intradural extramedullary schwannomas and meningiomas. We performed a retrospective study on MRI features for differentiating between intradural
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