TY  - CONF
AU  - Galldiks, Norbert
AU  - Hilgers, Julia
AU  - Ciantar, Keith
AU  - Kraft, Manuel
AU  - Peplinski, Jana-Marie
AU  - Werner, Jan-Michael
AU  - Wollring, Michael
AU  - Stetter, Isabelle
AU  - Ceccon, Garry
AU  - Fink, Gereon
AU  - Goldbrunner, Roland
AU  - Ruge, Maximilian
AU  - Shah, Nadim
AU  - Mottaghy, Felix
AU  - Langen, Karl-Josef
AU  - Kocher, Martin
AU  - Lohmann, Philipp
TI  - IMG-76. FET PET reveals considerable volumetric and spatial differences in tumor burden compared to conventional MRI in recurrent glioblastoma
SN  - 1523-5866
M1  - FZJ-2026-01606
PY  - 2025
AB  - AbstractBACKGROUNDIn recurrent glioblastomas, changes in areas of contrast enhancement and the T2/fluid-attenuated inversion recovery (FLAIR) signal on conventional MRI represent the mainstay for local therapy planning. Nevertheless, compared to conventional MRI, the information on the tumor burden obtained from amino acid PET may be considerably different in terms of volumetric assessment and spatial orientation.METHODSAt suspected recurrence, 56 patients with histomolecularly characterized glioblastoma underwent O-(2-[18F]-fluoroethyl)-L-tyrosine (FET) PET and MR imaging including contrast-enhanced and FLAIR sequences. Contrast-enhancing and FLAIR volumes were automatically segmented using HD-GLIO, and FET PET tumor volumes were assessed using the nnUNet-based JuST_BrainPET segmentation tool based on a tumor-to-brain ratio of ≥1.6. All segmentations were visually checked. Subsequently, an in-house developed workflow was used for a fully automated assessment of maximum and mean tumor-to-brain ratios. To evaluate spatial differences between the modalities, percentage overlap, the Dice similarity coefficient (DSC), and the 95th-percentile Hausdorff distance (HD95) were calculated. Recurrent disease was confirmed either by neuropathological evaluation of tissue obtained from surgery or stereotactic biopsy or prompted a change in treatment.RESULTSAll patients had measurable disease according to the PET RANO 1.0 criteria (mean tumor-to-brain ratio, 2.2±0.2). In 52 patients (93%), the FET PET tumor volume was significantly larger than the contrast-enhancing volume (36.5±31.6 mL vs. 18.5±19.7 mL; P<0.001). On average, FET PET tumor volumes extended by 30% beyond the combined contrast-enhancing and FLAIR volumes. The spatial similarity between FET uptake and contrast enhancement was limited (mean DSC, 0.40±0.23), with an HD95 of 17.8±12.2 mm. The comparison of FET uptake with the FLAIR hyperintensity revealed even lower spatial similarity (mean DSC, 0.35±0.16), and a higher boundary discrepancy (HD95, 30.0±14.2 mm).CONCLUSIONSOur results strongly support integrating both imaging modalities into treatment planning of patients with glioblastoma at recurrence.
T2  - 7th Quadrennial Meeting of the World Federation of Neuro-Oncology Societies
CY  - 20 Nov 2025 - 23 Nov 2025, Honolulu (USA)
Y2  - 20 Nov 2025 - 23 Nov 2025
M2  - Honolulu, USA
LB  - PUB:(DE-HGF)1
DO  - DOI:10.1093/neuonc/noaf201.1155
UR  - https://juser.fz-juelich.de/record/1053908
ER  -