Progress in magnetic resonance imaging of brain tumours.

PURPOSE OF REVIEW: Advances in magnetic resonance based techniques have yielded improvements in both high-resolution anatomical imaging and methods to evaluate physiology and function. This review focuses on recent developments in these techniques as applied to pretreatment staging and post-treatment evaluation of brain tumours.

RECENT FINDINGS: High-resolution spectroscopic imaging may contribute to pre-therapeutic grading and characterization of gliomas, as can diffusion techniques. The latter also hold promise in predicting survival in malignant supratentorial astrocytoma and could help to define areas for biopsy. Both methods can differentiate recurrent tumour from radiation injury. Perfusion-weighted magnetic resonance techniques offer potential markers of tumour angiogenesis and capillary permeability, and correlate well with vascular endothelial growth factor expression in grade II and grade III tumours. Functional magnetic resonance imaging can assess whether surgical treatment is feasible and select patients for intraoperative cortical stimulation. Combining multiple parameters in a magnetic resonance based diagnostic strategy could improve overall performance.

SUMMARY: Magnetic resonance imaging provides insights into the physiology of human tumours in a way that is both noninvasive and radiation free. We may expect from these new imaging methods greater specificity in diagnosis and useful tools with which to predict and assess response to therapy.