Impact of Relative T2-FLAIR Signal Intensity of Non-Enhancing Lesions Outside Residual Cavity in Early Follow-up MRI on Outcome of Lower Grade Gliomas

Abstract

Purpose T2-Fluid attenuated inversion recovery (FLAIR)hyperintensityoutside the residual cavity is one of the important MRI features in lowergrade gliomas (LGG), but its prognostic value needs to be further explored. The purpose of thisstudy was to investigate whether the relative signal intensity of T2-FLAIR outside the residual cavity (rFLAIR) can improve survival predictionofpost-treatment LGG patients or not. Methods Clinical and pathological data, and early follow-up MR imaging of 152 patients with LGG were reviewed.We calculatedrFLAIRwith Image J software.Logistic analysiswas used to explore the significant clinicaland conventional MRI factors, and rFLAIR on progressionfree survival (PFS) and overall survival (OS).Different models were setup to predict survival prognosis of LGG. Results Higher rFLAIR (1.80±0.84) of non-contrast-enhancing lesionsoutside residual cavity was detected in progression group (n=80) than that (1.55±0.33) of non-progression group (n = 72) (P<0.001)after radiotherapy.Multivariate analysis showed that higher rFLAIR(>1.595), as well as thick-linear and nodular enhancement of the residual cavity wall, were independent factors for the poor PFS and OS (both P<0.05). The cut-offrFLAIRof 1.595 could be used to predict poor PFS(HR 0.27, 95%CI 0.17-0.42) and OS (HR 0.22，95%CI 0.12-0.40)(P<0.001).Areas under the ROC curve (AUCs) for predicting poor PFS: clinical model 0.726, conventional MRI model 0.672, clinical + conventional MRI model 0.760, clinical + conventional MRI + rFLAIR combined model 0.827; AUCs for predicting poorer OS: clinical model 0.799, conventional MRI model 0.735, clinical + conventional MRI model 0.843, clinical + conventional MRI + rFLAIR combined model 0.880.Conclusions Our preliminary results indicated that higherrFALIR (>1.595) of non-contrast-enhancing lesionsoutside the residual cavity can be used as a biomarker of poor survival of LGG. Moreover,rFLAIR is helpful to improve the survival prediction of post-treatment LGG patients.