Accuracy of MR perfusion weighted imaging for cerebral glioma grading: a meta-analysis

Objective: To evaluate values of MR perfusion weighted imaging (PWT) in the grading of intracranial gliomas by a meta-analysis. Methods: All English and Chinese literatures published before November 2009 in PUBMED and CNKT (China National Knowledge Infrastructure) were searched. Literature searching requirements; (1) MR PWI with region of interest (ROI) must have been applied in the grading of gliomas; (2) histopathological results must have been used as the reference standards. In addition, after data extraction, a bivariate random-effect model and hierarchical weighted symmetric summary receiver-operating curve must have been utilized to pool the data. Furthermore, a meta regression method must have been applied to detect and analyze the factors that affected the diagnostic accuracy. Results: Overall, fourteen studies were included with a total amount of 1021 patients. The pooled sensitivity, specificity and diagnostic odds ratio with 95% of CI were 93% (89%-96%), 81% (73%-87%) and 55 (28-107), respectively. The factors that affected the diagnostic accuracy were the sample size, the ratio of malignant glioma, the injection rate of contrast agents, the repetition time and the cutoff value. Heterogeneity did exist among the results obtained from different studies. Conclusion: the relative cerebral blood volume (rCBV) of MR PWI can be referred to differentiate malignant cerebral gliomas from benign ones with sound sensitivity and specificity. However, there is not a unified threshold applied in the researches that have been conducted so far, and techniques used differ among the studies. In summary, clinical application values of rCBV of MR PWI are to be corroborated by further studies with a larger sample size.