Nuklearmedizin 2021; 60(02): 131-132
DOI: 10.1055/s-0041-1726701
Leuchtturm
Bildgebung und Therapie

Disentangling inflammatory from fibrotic disease activity by fibroblast activation protein imaging

Authors

  • C Schmidkonz

    1   Universitätsklinikum Erlangen, Nuklearmedizin, Erlangen

  • S Rauber

    2   Universitätsklinikum Erlangen, Rheumatologie, Erlangen

  • A Atzinger

    1   Universitätsklinikum Erlangen, Nuklearmedizin, Erlangen

  • TI Götz

    1   Universitätsklinikum Erlangen, Nuklearmedizin, Erlangen

  • A Soare

    2   Universitätsklinikum Erlangen, Rheumatologie, Erlangen

  • M Cordes

    1   Universitätsklinikum Erlangen, Nuklearmedizin, Erlangen

  • O Prante

    1   Universitätsklinikum Erlangen, Nuklearmedizin, Erlangen

  • P Ritt

    1   Universitätsklinikum Erlangen, Nuklearmedizin, Erlangen

  • T Bäuerle

    3   Universitätsklinikum Erlangen, Radiologie, Erlangen

  • M Köhner

    1   Universitätsklinikum Erlangen, Nuklearmedizin, Erlangen

  • U Haberkorn

    4   Universitätsklinikum Heidelberg, Nuklearmedizin, Heidelberg

  • T Kuwert

    1   Universitätsklinikum Erlangen, Nuklearmedizin, Erlangen

  • G Schett

    2   Universitätsklinikum Erlangen, Rheumatologie, Erlangen

  • A Ramming

    2   Universitätsklinikum Erlangen, Rheumatologie, Erlangen
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Ziel/Aim To date, there is no valuable tool to assess fibrotic disease activity in humans in vivo in a non-invasive way. This study aims to uncouple inflammatory from fibrotic disease activity in fibroinflammatory diseases such as IgG4-related disease.

Methodik/Methods In this cross-sectional clinical study, 27 patients with inflammatory, fibrotic and overlapping manifestations of IgG4-related disease underwent positron emission tomography (PET) scanning with tracers specific for fibroblast activation protein (FAP; 68Ga-FAP inhibitor (FAPI)-04), 18F-fluorodeoxyglucose (FDG), magnetic resonance imaging (MRI) and histopathological assessment. In a longitudinal approach, 18F-FDG and 68Ga-FAPI-04 PET/CT data were evaluated before and after immunosuppressive treatment and correlated to clinical and MRI data.

Ergebnisse/Results Using combination of 68Ga-FAPI-04 and 18F-FDG-PET, we demonstrate that non-invasive functional tracking of IgG4-related disease evolution from inflammatory towards a fibrotic outcome becomes feasible. 18F-FDG-PET positive lesions showed dense lymphoplasmacytic infiltration of IgG4 + cells in histology, while 68Ga-FAPI-04 PET positive lesions showed abundant activated fibroblasts expressing FAP according to results from RNA-sequencing of activated fibroblasts. The responsiveness of fibrotic lesions to anti-inflammatory treatment was far less pronounced than that of inflammatory lesions.

Schlussfolgerungen/Conclusions FAP-specific PET/CT permits the discrimination between inflammatory and fibrotic activity in IgG4-related disease. This finding may profoundly change the management of certain forms of immune-mediated disease, such as IgG4-related disease, as subtypes dominated by fibrosis may require different approaches to control disease progression, for example, specific antifibrotic agents rather than broad spectrum anti-inflammatory treatments such as glucocorticoids.


Publication History

Article published online:
08 April 2021

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