Glioma Infiltration Sign on High b-Value Diffusion-Weighted Imaging in Gliomas and Its Prognostic Value

Background: Glioma cells may infiltrate beyond the tumor margins revealed on conventional structural images. Purpose: To investigate whether the presence of a glioma infiltration sign on high b-value diffusion-weighted imaging (DWI) can predict the prognosis of gliomas. Study Type: Retrospective cohort. Subjects: Fifty-two patients with gliomas (14 WHO grade II; 13 WHO grade III; 25 WHO grade IV). Field Strength/Sequence: 3.0T, including a T1-weighted contrast-enhanced (T1w-CE) sequence, contrast-enhanced T2flair sequence, and a DWI sequence. Assessment: T1w-CE images and contrast-enhanced T2-flair images were used for identifying the tumor region for enhancing and nonenhancing gliomas, respectively. The glioma infiltration sign was defined as the presence of a peritumoral abnormal high signal region on DWI map, which was adjacent to the tumor region and had higher signal than surrounding areas. This sign was assessed on a high b-value DWI map with b53000 s/mm 2. For patients with glioma infiltration sign, DWI3000max, DWI1000max, ADC3000min, and ADC1000min were measured by drawing a region of interest over the peritumoral abnormal high signal region. Statistical Tests: Survival analysis was conducted by using Cox regression. Results: Glioma infiltration sign was observed in 28 (53.8%) patients. The occurrence rate of this sign was 92.0% in grade IV gliomas, 30.8% in grade III gliomas, and 7.1% in grade II gliomas. The glioma infiltration sign could independently predict both the progression-free survival (hazard ratio [HR], 95% confidence interval [CI] 58.58 [3.19-23.03], P< 0.001) and overall survival (HR, 95% CI511.90 [3.41-41.55], P< 0.001) after adjustment. For patients with glioma infiltration sign, DWI3000max (P50.005) and ADC3000min (P50.008) were both independent predictors of overall survival after adjustment, while DWI1000max and ADC1000min were not. Data Conclusion: The glioma infiltration sign on high b-value DWI is an independent predictor of poor prognosis in glioma patients. High b-value DWI might be a convenient method to detect glioma infiltration. Level of Evidence: 3 Technical Efficacy: Stage 2