A meta-analysis of arterial spin labelling perfusion values for the prediction of glioma grade.

Aim: To investigate the ability of arterial spin labelling (ASL) perfusion parameters to distinguish high-grade from low-grade gliomas.
Materials and Methods: The PubMed and EMBASE databases were systematically searched for relevant articles published up to September 2015. Studies that evaluated both high- and low-grade gliomas using ASL were included. The random effect model was used to calculate the standardised mean difference (SMD) of maximum mean absolute tumour blood flow values (aTBF _max , aTBF _mean ) and maximum mean relative tumour blood flow (rTBF _max , rTBF _mean ) between high- and low-grade gliomas.
Results: Nine studies encompassing 305 patients with high- and low-grade gliomas, met all inclusion and exclusion criteria and were included in the study. Compared with low-grade gliomas, high-grade gliomas had a significant increase in all ASL perfusion values: aTBF _max (SMD=0.70, 95% confidence interval [CI]: 0.22-1.19, p=0.0046); aTBF _mean (SMD=0.86, 95% CI: 0.2-1.52, p=0.01); rTBF _max (SMD=1.08, 95% CI: 0.54-1.63, p=0.0001) and rTBF _mean (SMD=0.88, 95% CI: 0.35-1.4, p=0.0011).
Conclusions: The current study results indicate that tumour blood flow from ASL differs significantly with respect to the glioma grade. Despite some limitations, there is evidence that ASL may be useful to distinguish high- and low-grade gliomas. Further larger-scale studies are necessary to examine the utility of ASL to distinguish tumour grade.
(Copyright © 2016 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.)