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Glioblastoma is one of the most aggressive cancers, but the molecular evolution is not fully understood. We used PET imaging combined with deep sequencing of glioblastoma biopsies at both the RNA and DNA levels to get a deeper insight into molecular evolution. In the clinical setting, PET imaging provides information about metabolically active tumor areas, but the molecular interpretation is unclear. Our primary objective was to perform an intratumoral spatial comparison of biopsies from potentially aggressive and less aggressive areas in glioblastomas according to PET scans. We used MRI co-registered with 11C-MET-PET (amino acid) and 18F-FDG PET (glucose) in order to obtain representative neurosurgical stereotactic biopsies from tumor areas with high accumulation of these two metabolites (hotspot), low accumulation (coldspot), and no accumulation as the periphery of six glioblastoma patients that were processed for whole genome, exome, and transcriptome sequencing. Differential gene expression and gene ontology analysis showed that hotspots were enriched in gene sets associated with DNA replication, cell cycle, and ligand-receptor interaction. Genome and exome analysis suggested hotspots and coldspots have similar mutational profiles. However, a limited number of hotspot-specific mutations and novel fusion transcripts indicated that hotspot-associated tumor cells developed from coldspot-associated tumor cells and point at the potential role of hotspot driver genes in glioblastoma evolution. Our findings reveal that hotspots in glioblastomas represent a more advanced stage of molecular evolution than coldspots. Citation Format: Atul Anand, Jeanette Krogh Petersen, Mark Burton, Martin Jakob Larsen, Lars van Andersen, Dylan Scott Harwood, Christian Bonde Pedersen, Frantz Rom Poulsen, Peter Grupe, Torben A. Kruse, Mads Thomassen, Bjarne Winther Kristensen. Deeper insight into intratumoral heterogeneity by MRI and PET-guided stereotactic biopsies from glioblastoma patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3796.