The role of diffusion-weighted imaging in patients with brain tumors.

TLDR

Diffusion‑weighted imaging, accelerated by echo‑planar techniques, has become a common tool for studying various diseases. The study aimed to determine whether DWIs and apparent diffusion coefficients could improve the diagnostic assessment of brain tumors. Using a 1.5‑T MR scanner, 56 patients with gliomas, metastases, or meningiomas were scanned; ADC values and DWI signal intensities were measured in solid tumor cores and peritumoral hyperintense zones, and correlated with tumor cellularity. ADC values were higher in low‑grade astrocytomas than in other tumors and correlated inversely with cellularity in astrocytic tumors and meningiomas, but DWIs did not detect peritumoral infiltration; thus ADC may predict astrocytic tumor malignancy, though overlap exists.

Abstract

BACKGROUND AND PURPOSE: Diffusion-weighted images (DWIs) have been used to study various diseases, particularly since echo-planar techniques shorten examination time. Our hypothesis was that DWIs and tumor apparent diffusion coefficients (ADCs) could provide additional useful information in the diagnosis 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 tumors, and 18 meningiomas). We determined ADC values and signal intensities on DWIs both in the solid portion of the tumor and in the peritumoral, hyperintense areas on T2-weighted images. We also evaluated the correlation between ADC values and tumor cellularity in both gliomas and meningiomas. RESULTS: The ADCs of low-grade (grade II) astrocytomas were significantly higher (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 with tumor cellularity for both astrocytic tumors (r = −.77) and meningiomas (r = −.67). CONCLUSION: The ADC may predict the degree of malignancy of astrocytic tumors, although there is some overlap between ADCs of grade II astrocytomas and glioblastomas.