Neuromas and meningiomas: evaluation of early enhancement with dynamic MR imaging.

PURPOSE To investigate the role of dynamic MR imaging in the differentiation of neuromas and meningiomas. METHODS Eleven patients with neuromas and 15 patients with meningiomas underwent dynamic contrast-enhanced MR imaging using a short TE FLASH sequence and a bolus injection of Gd-DTPA. RESULTS There was no significant difference between these tumors in the signal-enhancement increment at the late phase, which corresponds to the signal-enhancement increment between pre- and postcontrast images in conventional spin-echo imaging. However, the signal enhancement at the vascular phase, ie, the phase where the first passage of Gd-DTPA was recognized both in the arteries and veins, was approximately four times as high in meningiomas as in neuromas. The difference was statistically significant. Furthermore, meningiomas had a wider range of early signal enhancement than did neuromas, reflecting the histologic varieties: two angioblastic meningiomas had the highest values, and three fibroblastic the lowest values comparable with those of neuromas, while meningiomas with other subtypes had intermediate values. CONCLUSIONS The results of this study indicate that the evaluation of early enhancement with dynamic MR imaging is helpful in the differentiation of neuromas and meningiomas, and possibly in the crude prediction of pathologic subtypes of meningiomas.