Fig. 3

CONSORT flow diagram of the FOR2858 TSPO study (tissue-based aspects). The FOR2858 TSPO study cohort included in total 27 patients with GBM. All patients had received contrast-enhanced MRI, TSPO-PET and amino acid PET. Areas of interest were defined in an interdisciplinary exchange between the attending neurosurgeon and nuclear medicine specialist. Imaging-coordinated biopsy/resection along trajectory resulted in 14 patients with biopsy material and 13 with resection material for further analyses. Formalin-fixed and paraffin-embedded (FFPE) material from 26 patients with IDH-wildtype GBM (18 primary and 8 recurrent tumors) was used for further histological/molecular analyses. Tumor cell content was assessed by using H&E stains of each specimen with subdivision into the following categories: “no tumor”, “some tumor”, “infiltration zone”, “solid tumor” (see text for further explanations). In our stereotactical approach we collected multiple tissue samples from each individual patient that could match to different tumor cell content categories (for more detailed information compare Suppl. Table 2). After some dropouts, where no reliable immunohistochemical staining or no TSPO-PET value extraction was possible, 17–18 patients with solid tumor samples, 15–16 patients with infiltration zone samples, 12 patients with “some tumor” samples and 8–10 patients with no tumor were available for data evaluation (depending on the respective comparisons). For molecular analyses, fresh-frozen cryo material from 24 patients with IDH-wildtype GBM was collected in addition to the FFPE material. After exclusion of specimens with no solid tumor (5 patients) and specimens without sufficient RNA yield (1 patient) a subset of 18 patients with IDH-wildtype GBM (13 primary and 5 recurrent tumors) was available for molecular data evaluation.