Evaluation of residual acoustic schwannoma using gadolinium-DTPA enhanced magnetic resonance imaging with the fat suppression technique.

After subtotal resection of acoustic schwannomas, radiographic evaluation is necessary to evaluate tumor growth. With conventional gadolinium-DTPA T1-weighted magnetic resonance imaging, tumor delineation is often obscured by surgically placed fat. This occurs because fat has the same intensity as enhanced acoustic tumor. T1-weighted magnetic resonance fat suppression techniques can be used to eliminate the strong signal of fat tissue. When this technique is used in combination with gadolinium-DTPA, the definition of pathologic structures is improved in those areas containing large amounts of fat. Twelve patients who had subtotal resection of an acoustic schwannoma underwent gadolinium-DTPA enhanced magnetic resonance imaging using the fat suppression technique. Residual tumors were more conspicuous and had improved margin definition using the fat suppression technique compared to conventional gadolinium-DTPA T1-weighted images. These refinements in magnetic resonance imaging represent a significant advance in the assessment of residual acoustic tumors.