Multiparametric MRI as an early biomarker of individual therapy effects during concomitant treatment of brain tumours

The aim of this study was to determine the ability of multiparametric MRI to identify the early effects of individual treatment, during combined chemo‐radiotherapy on brain tumours. Eighty male rats bearing 9L gliosarcomas were randomized into four groups: untreated, anti‐angiogenic therapy (SORA group), microbeam radiation therapy (MRT group) and both treatments (MRT+SORA group). Multiparametric MRI (tumour volume, diffusion‐weighted MR imaging (ADC), blood volume fraction (BVf), microvessel index (VSI), vessel wall integrity (AUCP846) and tissue oxygen saturation (StO2)) was performed 1 day before and 2, 5 and 8 days after treatment initiation. Unpaired t‐tests and one‐way ANOVA were used for statistical analyses. Each MR parameter measured in our protocol was revealed to be sensitive to tumour changes induced by any of the therapies used (individually or combined). When compared with untreated tumours, SORA induced a decrease in BVf, VSI, StO2 and AUCP846, MRT generated an increase in ADC and AUCP846 and combined therapies yielded mixed effects: an increase in ADC and AUCP846 and a decrease in BVf, StO2 and AUCP846. MRT and MRT+SORA significantly slowed tumour growth. Despite these two groups presenting with similar tumour sizes, the information yielded from MR multiparameter assessment indicated that, when used concomitantly, each therapy induced distinguishable and appreciable physiological changes in the tumour. Our results suggest that multiparametric MRI can monitor the effects of individual treatments, used concomitantly, on brain tumours. Such monitoring would be useful for the detection of tumour resistance to drug/radiotherapy in patients undergoing concomitant therapies. Copyright © 2015 John Wiley & Sons, Ltd. The goal of this study was to evaluate if a multiparametric MRI (diffusion, vessel size, blood volume, oxygenation and permeability) was able to identify early effects of individual treatment during a combined chemo‐radiotherapy on a 9L gliosarcoma. Although radio and chemo‐radio groups presented similar tumour sizes, the information provided by multiparametric MRI allowed us to distinguish the effect of each therapy when used concomitantly. Such monitoring could be useful to detect tumour escape from drug/radiotherapy in patients under concomitant therapies.