Advanced magnetic resonance (MR) imaging techniques provide physiologic information that complements the anatomic information available from conventional MR imaging. We evaluated the roles of diffusion and perfusion imaging for the assessment of grade and type of histologically proven intraaxial
brain tumors. A total of 28 patients with intraaxial
brain tumors underwent conventional MR imaging (T2- and T1-weighted sequences after
gadobenate dimeglumine injection), diffusion imaging and T2*-weighted echo-planar perfusion imaging. Examinations were performed on 19 patients during initial diagnosis and on nine patients during follow-up
therapy. Determinations of relative cerebral blood volume (rCBV) and apparent diffusion coefficient (ADC) were performed in the solid parts of each
tumor, peritumoral region and contralateral white matter. For
gliomas, rCBV values were greater in high-grade than in low-grade
tumors (3.87+/-1.94 versus 1.30+/-0.42) at the time of initial diagnosis. rCBV values were increased in all recurrent
tumors, except in one patient who presented with a combination of recurrent
glioblastoma and massive radionecrosis on histology. Low-grade
gliomas had low rCBV even in the presence of contrast medium enhancement. Differentiation between high- and low-grade
gliomas was not possible using diffusion-weighted images and ADC values alone. In the peritumoral areas of untreated high-grade
gliomas and
metastases, the mean rCBV values were higher for high-grade
gliomas (1.7+/-0.37) than for
metastases (0.54+/-0.18) while the mean ADC values were higher for
metastases. The rCBV values of four
lymphomas were low and the signal intensity-time curves revealed a significant increase in signal intensity after the first pass of
gadobenate dimeglumine. Diffusion and perfusion imaging, even with relatively short imaging and data processing times, provide important information for lesion characterization.