{
  "abstract": "Background: Translocator protein (TSPO)-PET imaging facilitates monitoring of glioblastoma in preclinical models and patients. However, specificity of TSPO-PET signals remains to be investigated. In this study, we aimed to decipher exact contributions of cellular and extracellular compartments including the impact of blood-brain barrier (BBB) disruption to TSPO-PET signals in an experimental glioblastoma mouse model.\n\nMethods: Mice with implanted glioblastoma (SB28; n = 36 early-stage, n = 39 late-stage; GFP(+)) were injected with the TSPO tracer [18F]GE-180 (21 MBq ± 1.5 MBq). Dynamic 60 min microPET scans were performed with and without prior blocking by excessive cold radiotracer. Tumors were dissociated, followed by cell sorting of tumor cells, tumor-associated microglia/macrophages (TAMs, CD11b(+)) and non-tumor/non-TAM (i.e. remaining) cells with subsequent gamma emission measures and flow cytometry (scRadiotracing) to calculate radioactivity per single cell. PET signals and single-cell tracer uptake in tumors and non-lesional hemispheres were compared between blocked and unblocked conditions. N = 10 mice were intravenously injected with fluorescent Dextran to investigate BBB disruption by confocal microscopy in correlation with TSPO-PET signals of the same animals.\n\nResults: TSPO-PET indicated strong but incomplete signal reduction after blocking in tumors (early-stage: -72%; late-stage: -59%, p < 0.001) and contralateral hemispheres (early stage: -65%, late-stage: -63%, p < 0.001) compared to unblocked animals. We found nearly complete blocking of radiotracer uptake across all analyzed cell fractions (tumor cells: -95%, p = 0.0039; TAMs: -98%, p < 0.0001; remaining cells: -99%, p = 0.0033) compared to unblocked mice, regardless of tumor stages. There was a significant correlation of PET signal reduction (R=-0.824, p = 0.0034) as well as residual PET signal upon blocking (R = 0.809, p = 0.0046) with Dextran intensity.\n\nConclusion: Specificity of TSPO-PET signals in experimental glioblastoma reaches 72% in early-stage tumors, but decreases to 59% in late-stage SB28 tumors, due to progressive contributions of BBB disruption. Non-specific TSPO tracer uptake is driven by BBB disruption and fully allocated to the extracellular compartment, whereas cellular TSPO tracer uptake shows strong specificity.\n\nSupplementary Information: The online version contains supplementary material available at https://doi.org/10.1007/s00259-026-08187-5.",
  "abstract_shown": true,
  "affiliations": [
    "Department of Nuclear Medicine, LMU University Hospital, LMU Medizin, Ludwig-Maximilians-Universität München, Munich, Germany",
    "Institute for Stroke and Dementia Research, LMU University Hospital, LMU Medizin, Ludwig-Maximilians-Universität München, Munich, Germany",
    "Department of Neurosurgery, LMU University Hospital, LMU Medizin, Ludwig-Maximilians-Universität München, Munich, Germany",
    "Munich Cluster for Systems Neurology (SyNergy), Munich, Germany",
    "German Center for Neurodegenerative Diseases (DZNE) Munich, Munich, Germany",
    "Russell H. Morgan Department of Radiology and Radiological Sciences, Johns Hopkins School of Medicine, Baltimore, MD USA",
    "Department of Neurology, LMU University Hospital, LMU Medizin, Ludwig-Maximilians-Universität München, Munich, Germany",
    "German Cancer Consortium (DKTK), Partner Site Munich, A Partnership Between the DKFZ Heidelberg and the University Hospital of the LMU, Munich, Germany",
    "Bavarian Cancer Research Center (BZKF), Partner Site Munich, Munich, Germany",
    "Institute of Clinical Neuroimmunology, LMU University Hospital, LMU Medizin, Ludwig-Maximilians-Universität München, Munich, Germany",
    "Biomedical Center (BMC), LMU Medizin, Ludwig-Maximilians-Universität München, Martinsried, Germany"
  ],
  "article_type": "research article",
  "arxiv": null,
  "author_total": 18,
  "authors": [
    {
      "affs": [
        0
      ],
      "name": "Leonie Hoermann"
    },
    {
      "affs": [
        1
      ],
      "name": "Fatma Burcu Seker"
    },
    {
      "affs": [
        2
      ],
      "name": "Emanuel Joseph"
    },
    {
      "affs": [
        3
      ],
      "name": "Sabrina V Kirchleitner"
    },
    {
      "affs": [
        4
      ],
      "name": "Jens Blobner"
    },
    {
      "affs": [
        0,
        4
      ],
      "name": "Lea H Kunze"
    },
    {
      "affs": [
        0
      ],
      "name": "Justus F Thevis"
    },
    {
      "affs": [
        0
      ],
      "name": "Selina Hummel"
    },
    {
      "affs": [
        0
      ],
      "name": "Amelie L Englert"
    },
    {
      "affs": [
        0
      ],
      "name": "Karin Wind-Mark"
    },
    {
      "affs": [
        0
      ],
      "name": "Adrien Holzgreve"
    },
    {
      "affs": [
        0,
        3
      ],
      "name": "Simon Lindner"
    },
    {
      "affs": [
        0,
        5
      ],
      "name": "Rudolf A Werner"
    },
    {
      "affs": [
        2,
        6,
        7,
        8
      ],
      "name": "Louisa von Baumgarten"
    },
    {
      "affs": [
        0,
        7,
        8
      ],
      "name": "Nathalie L Albert"
    },
    {
      "affs": [
        1,
        3
      ],
      "name": "Nikolaus Plesnila"
    },
    {
      "affs": [
        0,
        3,
        4,
        7,
        8
      ],
      "name": "Matthias Brendel"
    },
    {
      "affs": [
        0,
        9,
        10
      ],
      "name": "Laura M Bartos",
      "orcid": "0009-0007-6158-319X"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/b71w84z4qkq01.bib",
  "cited_by": 0,
  "doi": "10.1007/s00259-026-08187-5",
  "fulltext_url": "https://pmc.ncbi.nlm.nih.gov/articles/PMC13727962/",
  "id": "b71w84z4qkq01",
  "issns": [
    "1619-7070",
    "1619-7089"
  ],
  "landing_url": "https://doi.org/10.1007/s00259-026-08187-5",
  "language": "en",
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "heading",
      "Original Article"
    ],
    [
      "openalex",
      "2741|Medical Imaging Techniques and Applications"
    ]
  ],
  "openalex": "W7214087780",
  "pdf_url": "https://link.springer.com/content/pdf/10.1007/s00259-026-08187-5.pdf",
  "pmcid": "PMC13727962",
  "pmid": "42778718",
  "published": "2026-09-24",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/b71w84z4qkq01.ris",
  "sources": [
    {
      "first_seen": "2026-11-06T12:23:44Z",
      "native_id": "PMC13727962",
      "source": "pmc",
      "url": "https://doi.org/10.1007/s00259-026-08187-5"
    }
  ],
  "subjects": [
    {
      "field": "medicine",
      "origin": "openalex:2741|Medical Imaging Techniques and Applications",
      "subfield": "imaging"
    }
  ],
  "title": "Allocation of TSPO-PET signals to cellular and extracellular compartments in dependence of blood-brain barrier disruption in experimental glioblastoma",
  "title_text": "Allocation of TSPO-PET signals to cellular and extracellular compartments in dependence of blood-brain barrier disruption in experimental glioblastoma",
  "type": "peer-reviewed",
  "updated_at": "2026-11-07T12:21:03Z",
  "url": "https://research.draconitic.com/paper/b71w84z4qkq01",
  "venue": "European Journal of Nuclear Medicine and Molecular Imaging",
  "versions": []
}