The role of diffusion-weighted imaging in patients with brain turners

BACKGROUND AND PURPOSE: Diffusion-weighted images (DWIs) have been used to study various diseases, particularly since echo-planar techniques shorten e xamination time. Our hypothesis was that DWIs and tumor apparent diffusion coefficients (ADCs) could provide additional useful information in the diag nosis of patients with brain tumors. METHODS: Using a 1,5-T MR unit, we examined 56 patients with histologically verified or clinically diagnosed brain tumors (17 gliomas, 21 metastatic t umors, and 18 meningiomas), We determined ADC values and signal intensities on DWIs both in the solid portion of the tumor and in the peritumoral, hyp erintense areas on T2-weighted images. We also evaluated the correlation be tween ADC values and tumor cellularity in both gliomas and meningiomas. RESULTS: The ADCs of low-grade (grade II) astrocytomas were significantly h igher (P = .0004) than those of other tumors. Among astrocytic tumors, ADCs were higher in grade II astrocytomas (1.14 +/- 0.18) than in glioblastomas (0.82 +/- 0.13). ADCs and DWIs were not useful in determining the presence of peritumoral neoplastic cell infiltration. The ADC values correlated wit h tumor cellularity for both astrocytic tumors (r = -.77) and meningiomas ( r = -.67). CONCLUSION: The ADC may predict the degree of malignancy of astrocytic tumo rs, although there is some overlap between ADCs of grade II astrocytomas an d glioblastomas.