Prognostic value of perfusion-weighted imaging in brain glioma: a prospective study

Introduction: Magnetic resonance (MR) imaging biopsy targeting may fail to identify malignant areas in brain gliomas. Considering the reported differences in relative cerebral blood volume (rCBV) ratios among tumour grades, we evaluated whether routine perfusion-weighted imaging (PWI) could usefully implement preoperative imaging to guide the biopsy by detecting those areas bearing a higher yield for malignancy. Methods: We prospectively studied a series of 55 consecutive patients presenting with newly diagnosed brain glioma using preoperative MR imaging and PWI. The pathological diagnosis was established by stereotactic biopsy in 29 cases and by open craniotomy in 24 cases. The patients were followed for up to 5 years after the diagnosis to evaluate their survival. Results: The rCBV maps are particularly sensitive for the perfused part of the tumour as to small regional changes and make it possible to visualize malignant non-enhancing areas. In clinical practice, maximum rCBV ratios are the only useful PWI parameter. In our experience, PWI allowed better localization of the most malignant part of the tumour but with less precise demarcation of its borders. Added to diagnostic MR imaging, PWI improved the choice of targets for biopsy and, subsequently, the diagnosis accuracy. Further clinical follow-up confirmed the accuracy of the tumor grade established on the PWI-oriented biopsies. Conclusions: We found PWI to be quite valuable in the imaging assessment of brain gliomas, correlating significantly with the tumour grade and the final outcome (p less than 0.01). PWI was useful in discriminating high- from low-grade gliomas and detecting malignant areas even when not enhancing with great specificity and sensitivity.