title: Diffusion MR Characteristics Following Concurrent Radiochemotherapy Predicts Progression-Free and Overall Survival in Newly Diagnosed Glioblastoma.
abstract: The standard of care for newly diagnosed glioblastoma (GBM) is surgery, then radiotherapy (RT) with concurrent temozolomide (TMZ), followed by adjuvant TMZ. We hypothesized patients with low diffusivity measured using apparent diffusion coefficient (ADC) histogram analysis evaluated after RT+TMZ, prior to adjuvant TMZ, would have a significantly shorter progression-free (PFS) and overall survival (OS). To test this hypothesis we evaluated 120 patients with newly diagnosed GBM receiving RT+TMZ followed by adjuvant TMZ. MRI was performed after completion of RT+TMZ, prior to initiation of adjuvant TMZ. A double Gaussian mixed model was used to describe the ADC histograms within the enhancing tumor, where ADCLand ADCHwere defined as the mean ADC value of the lower and higher Gaussian distribution, respectively. An ADCLvalue of 1.0 um2/ms and ADCHvalue of 1.6 um2/ms were used to stratify patients into high and low risk categories. Results suggest patients with low ADCLhad significantly shorter PFS (Cox Hazard Ratio = 0.12, P = 0.0006). OS was significantly shorter with low ADCLtumors, showing a median OS of 407 vs. 644 days (Cox Hazard Ratio = 0.31, P = 0.047). ADCHwas not predictive of PFS or OS when accounting for age and ADCL. In summary, newly diagnosed glioblastoma patients with low ADCLafter completion of RT+TMZ are likely to progress and die earlier than patients with higher ADCL. Results suggest ADC histogram analysis may be useful for patient risk stratification following completion of RT+TMZ.
authors.affiliation: Dept. of Radiological Sciences, David Geffen School of Medicine at UCLA.
authors.forename: Warren
authors.initials: W
authors.lastname: Chang
authors.affiliation: Dept. of Radiological Sciences, David Geffen School of Medicine at UCLA.
authors.forename: Whitney B
authors.initials: WB
authors.lastname: Pope
authors.affiliation: Dept. of Radiological Sciences, David Geffen School of Medicine at UCLA; Dept. of Biomedical Physics, David Geffen School of Medicine at UCLA.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Harris
authors.affiliation: Dept. of Radiological Sciences, David Geffen School of Medicine at UCLA; Dept. of Biomedical Physics, David Geffen School of Medicine at UCLA.
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Hardy
authors.affiliation: Dept. of Radiological Sciences, David Geffen School of Medicine at UCLA; Dept. of Bioengineering, Henry Samueli School of Engineering and Applied Science at UCLA.
authors.forename: Kevin
authors.initials: K
authors.lastname: Leu
authors.affiliation: Dept. of Neurology, David Geffen School of Medicine at UCLA; UCLA Neuro-Oncology Program.
authors.forename: Reema R
authors.initials: RR
authors.lastname: Mody
authors.affiliation: Dept. of Neurology, David Geffen School of Medicine at UCLA; UCLA Neuro-Oncology Program.
authors.forename: Phioanh L
authors.initials: PL
authors.lastname: Nghiemphu
authors.affiliation: Dept. of Neurology, David Geffen School of Medicine at UCLA; UCLA Neuro-Oncology Program.
authors.forename: Albert
authors.initials: A
authors.lastname: Lai
authors.affiliation: Dept. of Neurology, David Geffen School of Medicine at UCLA; UCLA Neuro-Oncology Program.
authors.forename: Timothy F
authors.initials: TF
authors.lastname: Cloughesy
authors.affiliation: Dept. of Radiological Sciences, David Geffen School of Medicine at UCLA; Dept. of Biomedical Physics, David Geffen School of Medicine at UCLA; Dept. of Bioengineering, Henry Samueli School of Engineering and Applied Science at UCLA; UCLA Neuro-Oncology Program; Dept. of Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine at UCLA.
authors.forename: Benjamin M
authors.initials: BM
authors.lastname: Ellingson
keywords: ADC Histogram Analysis; Diffusion MRI; Glioblastoma