Usefulness of PRESTO magnetic resonance imaging for the differentiation of schwannoma and meningioma in the cerebellopontine angle.

The principles of echo-shifting with a train of observations (PRESTO) magnetic resonance (MR) imaging technique employs an MR sequence that sensitively detects susceptibility changes in the brain. The effectiveness of PRESTO MR imaging was examined for distinguishing between cerebellopontine angle (CPA) schwannomas and meningiomas in 24 patients with CPA tumors, 12 with vestibular schwannomas, and 12 with meningiomas. Histopathological study of surgical specimens showed that 11 of the 12 schwannomas contained hemosiderin deposits and all had microhemorrhages. One meningioma contained hemosiderin deposits and two involved microhemorrhages. Abnormal vessel proliferation, and dilated and thrombosed vessels were observed in all schwannomas and in 4 meningiomas. In addition to MR imaging with all basic sequences, PRESTO MR imaging and computed tomography were performed. PRESTO imaging showed significantly more schwannomas (n = 12) than meningiomas (n = 2) exhibited intratumoral spotty signal voids which were isointense to air in the mastoid air cells (p < 0.001). These spotty signal voids were significantly associated with histopathologically demonstrated hemosiderin deposits (p < 0.001), microhemorrhages (p < 0.01), and abnormal vessels (p < 0.04). The visualization of spotty signal voids on PRESTO images is useful to distinguish schwannomas from meningiomas.