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OBJECTIVE:To assess the value of spectroscopic and perfusion MRI for glioma grading and for distinguishing glioblastomas from metastases and from CNS lymphomas.METHODS:The authors examined 79 consecutive patients with first detection of a brain neoplasm on nonenhanced CT scans and no therapy prior to evaluation.Spectroscopic MRI;arterial spin-labeling MRI for measuring cerebral blood flow(CBF);first-pass dynamic,susceptibility-weighted,contrast-enhanced MRI for measuring cerebral blood volume;and T1-weighted dynamic contrast-enhanced MRI were performed.Receiver operating characteristic analysis was performed,and optimum thresholds for tumor classification and glioma grading were determined.RESULTS:Perfusion MRI had a higher diagnostic performance than spectroscopic MRI.Because of a significantly higher tumor blood flow in glioblastomas compared with CNS lymphomas,a threshold value of 1.2 for CBF provided sensitivity of 97%,specificity of 80%,positive predictive value(PPV)of 94%,and negative predictive value(NPV)of 89%.Because CBF was significantly higher in peritumoral nonenhancing T2-hyperintense regions of glioblastomas compared with metastases,a threshold value of 0.5 for CBF provided sensitivity,specificity,PPV,and NPV of 100%,71%,94%,and 100%.Glioblastomas had the highest tumor blood flow values among all other glioma grades.For discrimination of glioblastomas from grade 3 gliomas,sensitivity was 97%,specificity was 50%,PPV was 84%,and NPV was 86%(CBF threshold value of 1.4),and for discrimination of glioblastomas from grade 2 gliomas,sensitivity was 94%,specificity was 78%,PPV was 94%,and NPV was 78%(CBF threshold value of 1.6).CONCLUSION:Perfusion MRI is predictive in distinguishing glioblastomas from metastases,CNS lymphomas and other gliomas vs MRI and magnetic resonance spectroscopy.