% IMPORTANT: The following is UTF-8 encoded.  This means that in the presence
% of non-ASCII characters, it will not work with BibTeX 0.99 or older.
% Instead, you should use an up-to-date BibTeX implementation like “bibtex8” or
% “biber”.

@INPROCEEDINGS{Galldiks:1053908,
      author       = {Galldiks, Norbert and Hilgers, Julia and Ciantar, Keith and
                      Kraft, Manuel and Peplinski, Jana-Marie and Werner,
                      Jan-Michael and Wollring, Michael and Stetter, Isabelle and
                      Ceccon, Garry and Fink, Gereon and Goldbrunner, Roland and
                      Ruge, Maximilian and Shah, Nadim and Mottaghy, Felix and
                      Langen, Karl-Josef and Kocher, Martin and Lohmann, Philipp},
      title        = {{IMG}-76. {FET} {PET} reveals considerable volumetric and
                      spatial differences in tumor burden compared to conventional
                      {MRI} in recurrent glioblastoma},
      issn         = {1523-5866},
      reportid     = {FZJ-2026-01606},
      year         = {2025},
      abstract     = {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.},
      month         = {Nov},
      date          = {2025-11-20},
      organization  = {7th Quadrennial Meeting of the World
                       Federation of Neuro-Oncology Societies,
                       Honolulu (USA), 20 Nov 2025 - 23 Nov
                       2025},
      cin          = {INM-4},
      ddc          = {610},
      cid          = {I:(DE-Juel1)INM-4-20090406},
      pnm          = {5253 - Neuroimaging (POF4-525)},
      pid          = {G:(DE-HGF)POF4-5253},
      typ          = {PUB:(DE-HGF)1},
      doi          = {10.1093/neuonc/noaf201.1155},
      url          = {https://juser.fz-juelich.de/record/1053908},
}