Intratumoral Microhemorrhages on T2*-Weighted Gradient-Echo Imaging Helps Differentiate Vestibular Schwannoma From Meningioma

K Thamburaj,G Menon,B Thomas,S Nair,V.V Radhakrishnan

doi:10.3174/ajnr.a0887

Abstract

Vestibular schwannomas (VS) may be difficult to differentiate from cerebellopontine angle (CPA) meningiomas. Demonstration of microhemorrhages in VS on T2*-weighted gradient-echo (GRE) sequences may have potential value to differentiate VS from CPA meningiomas. In this prospective study of 20 patients, MR imaging was performed with T2*-weighted GRE in addition to all basic sequences. Histopathologic examination was performed after surgery. Intratumoral hemosiderin was confirmed by pigment staining. There were 15 patients in the VS group with 16 VS and 5 in the meningioma group with 5 posterior fossa meningiomas. Fourteen of the 16 VS and all 5 meningiomas were treated surgically and were confirmed on histopathologic examination. T2*-weighted GRE identified microhemorrhages on T2*-weighted sequence in 15 (93.75%) of the 16 VS. CT excluded calcification in all VS. T2-weighted turbo spin-echo (TSE) and fluid-attenuated inversion recovery (FLAIR) images recognized microhemorrhages in 2 cases. Pigment staining confirmed hemosiderin in all 14 surgically treated VS, and none of the meningiomas showed microhemorrhages on MR imaging. For the detection of microhemorrhages, T2*-weighted GRE showed a sensitivity of 93.8%, specificity of 100%, positive predictive value of 100%, and negative predictive value of 83.3%. The sensitivity of T2 TSE and FLAIR for microhemorrhage was 12.5%. The Fisher exact test showed a statistically significant difference in the differentiation of VS from meningioma on the basis of detection of microhemorrhages (P < .01). Most VS demonstrate microhemorrhages on T2*-weighted GRE. This finding is useful to differentiate VS from CPA meningiomas. T2*-weighted GRE should be used as a basic sequence to evaluate CPA tumors. Identification of microhemorrhages may have the potential to assess the aggressive biologic behavior of VS.

Highlights

AND PURPOSE: Vestibular schwannomas (VS) may be difficult to differentiate from cerebellopontine angle (CPA) meningiomas
A tumor in the internal auditory canal (IAC) with dilation of the canal is highly suggestive of VS
Signs such as the presence of hyperostosis, calcification, broad base of the tumor against the tentorium, and a dural tail may favor the diagnosis of a meningioma.[2]

Summary

Methods

In this prospective study of 20 patients, MR imaging was performed with T2*-weighted GRE in addition to all basic sequences. MR imaging of the brain was performed with a 1.5T system (Avanto; Siemens, Erlangen, Germany) with a phased array head matrix coil. We performed this imaging with a T2weighted turbo spin-echo (TSE) sequence in the sagittal (TR, 4000 ms; TE, 112 ms; echo-train length (ETL), 13; number of acquisitions, 1) and axial planes (TR, 3010 ms; TE, 82 ms; ETL, 5; acquisition, 1), T1-weighted spin-echo (SE) in the axial plane (TR, 476 ms; TE, 11 ms; acquisitions 1), fast fluid-attenuated inversion recovery (FLAIR) in the axial plane (TI, 2500 ms; TR, 9000 ms; TE, 109 ms; acquisition, 1), T2*-weighted GRE in the axial plane (TR, 800 ms; TE, 26 ms; flip angle, 12°; acquisition, 1), and postgadolinium T1-weighted SE in all 3 orthogonal planes (TR, 550 or 805 ms; /TE, 11 ms; acquisition, 1). We counted the number of hypointense dots in each tumor on MR imaging visually and measured the size of each hypointense dot with an electronic caliper

Results

Discussion

Conclusion