Multimodal Imaging-defined Subregions in Newly-diagnosed Glioblastoma: Impact on Overall Survival.
Authors of this article are:
John F, Bosnyák E, Robinette NL,, Amit-Yousif AJ,, Barger GR, Shah KD, Michelhaugh SK, Klinger NV, Mittal S,, Juhász C,.
A summary of the article is shown below:
BACKGROUND: Although glioblastomas are heterogeneous brain-infiltrating tumors, their treatment is mostly focused on the contrast-enhancing tumor mass. In this study, we combined conventional MRI, diffusion-weighted imaging (DWI), and amino acid PET to explore imaging-defined glioblastoma subregions and evaluate their potential prognostic value.METHODS: Contrast-enhanced T1, T2/FLAIR MR images, apparent diffusion coefficient (ADC) maps from DWI, and alpha-[ 11C]-methyl-L-tryptophan (AMT)-PET images were analyzed in 30 patients with newly-diagnosed glioblastoma. Five tumor subregions were identified based on a combination of MRI contrast enhancement, T2/FLAIR signal abnormalities, and AMT uptake on PET. ADC and AMT uptake tumor/contralateral normal cortex (T/N) ratios in these tumor subregions were correlated, and their prognostic value was determined.RESULTS: A total of 115 MRI/PET-defined subregions were analyzed. Most tumors showed not only a high-AMT uptake (T/N ratio >1.65, N=27) but also a low-uptake subregion (N=21) within the contrast-enhancing tumor mass. High AMT uptake extending beyond contrast enhancement was also common (N=25) and was associated with low ADC (r=-0.40, p=0.05). Higher AMT uptake in the contrast-enhancing tumor subregions was strongly prognostic for overall survival (HR: 7.83, [95%]CI: 1.98-31.02, p=0.003), independent of clinical and molecular genetic prognostic variables. Non-resected high-AMT uptake subregions predicted the sites of tumor progression on post-treatment PET performed in 10 patients.CONCLUSIONS: Glioblastomas show heterogeneous amino acid uptake with high-uptake regions often extending into non-enhancing brain with high cellularity; non-resection of these predict the site of post-treatment progression. High tryptophan uptake values in MRI contrast-enhancing tumor subregions is a strong, independent imaging marker for longer overall survival.
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