title: Evaluation of absolute and normalized apparent diffusion coefficient (ADC) values within the post-operative T2/FLAIR volume as adverse prognostic indicators in glioblastoma.
abstract: To evaluate the association of normalized and absolute ADC metrics with progression free survival (PFS) and overall survival (OS) in patients treated for glioblastoma multiforme (GBM). Fifty-two patients with preradiotherapy diffusion weighted imaging treated with post-operative chemoradiation for GBM were evaluated. Region of interest analysis for ADC metrics including mean and minimum ADC value (ADCmean) and (ADCmin) was performed within the T2/FLAIR volume. Normalized (N)ADC values were generated relative to contralateral white matter. PFS and OS were analyzed relative to ADC parameters using a regression model. Kaplan-Meier and Cox proportional hazards analysis with respect to (N)ADCmean, and (N)ADCmin was performed. A (N)ADC threshold <1.3 within the T2/FLAIR volume was analyzed with respect to PFS and OS. Regression analysis indicated that normalized ADC values provide the strongest association with PFS and OS. Kaplan-Meier analysis revealed a non-significant trend toward inferior PFS and OS associated with (N)ADCmean <1.7, and a significant decrement to PFS and OS associated with (N)ADCmin <0.3. (N)ADCmin was a significant prognostic factor when taking into account age, performance status, and extent of resection. ADC thresholding analysis revealed that a retained volume of >0.45 cc per mL FLAIR volume was associated with a trend toward inferior PFS and OS. In the post-operative, pre-radiotherapy setting, the (N)ADCmin is the strongest predictor of outcomes in patients treated for GBM. ADC thresholding analysis indicates that a large volume of normalized ADC value <1.3 may be associated with adverse outcomes.
authors.affiliation: Department of Radiation Oncology, Medical College of Wisconsin, 9200 W. Wisconsin Avenue, Froedtert Hospital East Clinics 3rd Floor, Milwaukee, WI, 53226, USA, aelson1672@gmail.com.
authors.forename: Andrew
authors.initials: A
authors.lastname: Elson
authors.forename: Joseph
authors.initials: J
authors.lastname: Bovi
authors.forename: Malika
authors.initials: M
authors.lastname: Siker
authors.forename: Chris
authors.initials: C
authors.lastname: Schultz
authors.forename: Eric
authors.initials: E
authors.lastname: Paulson
mesh_terms: D000368:Aged; D001932:Brain Neoplasms / Q000175:diagnosis* / Q000601:surgery; D038524:Diffusion Magnetic Resonance Imaging; D018572:Disease-Free Survival; D005260:Female; D005500:Follow-Up Studies; D005909:Glioblastoma / Q000175:diagnosis* / Q000601:surgery; D006801:Humans; D007091:Image Processing, Computer-Assisted; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local; D012044:Regression Analysis; D016896:Treatment Outcome