Bone formation in ankylosing spondylitis during anti-tumour necrosis factor therapy imaged by 18F-fluoride positron emission tomography

Stefan T.G. Bruijnen, Nicki J.F. Verweij, Leonie M. van Duivenvoorde, Nathalie Bravenboer, Dominique L.P. Baeten, Christiaan J. van Denderen, Irene E. van der Horst-Bruinsma, Alexandre E. Voskuyl, Martijn Custers, Peter M. van de Ven, Joost C.J. Bot, Bouke J.H. Boden, Adriaan A. Lammertsma, Otto S.H. Hoekstra, Pieter G.H.M. Raijmakers, Conny J. van der Laken*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review


Objectives. Excessive bone formation is an important hallmark of AS. Recently it has been demonstrated that axial bony lesions in AS patients can be visualized using 18F-fluoride PET-CT. The aim of this study was to assess whether 18F-fluoride uptake in clinically active AS patients is related to focal bone formation in spine biopsies and is sensitive to change during anti-TNF treatment. Methods. Twelve anti-TNF-naïve AS patients [female 7/12; age 39 years (SD 11); BASDAI 5.5 ± 1.1] were included. 18 F-fluoride PET-CT scans were performed at baseline and in two patients, biopsies were obtained from PET-positive and PET-negative spine lesions. The remaining 10 patients underwent a second 18F-fluoride PET-CT scan after 12 weeks of anti-TNF treatment. PET scans were scored visually by two blinded expert readers. In addition, 18F-fluoride uptake was quantified using the standardized uptake value corrected for individual integrated whole blood activity concentration (SUVAUC). Clinical response to anti- TNF was defined according to a≥20% improvement in Assessment of SpondyloArthritis international Society criteria at 24 weeks. Results. At baseline, all patients showed at least one axial PET-positive lesion. Histological analysis of PET-positive lesions in the spine confirmed local osteoid formation. PET-positive lesions were found in the costovertebral joints (43%), facet joints (23%), bridging syndesmophytes (20%) and non-bridging vertebral lesions (14%) and in SI joints (75%). After 12 weeks of anti-TNF treatment, 18F-fluoride uptake in clinical responders decreased significantly in the costovertebral (mean SUVAUC -1.0; P < 0.001) and SI joints (mean SUVAUC -1.2; P = 0.03) in contrast to non-responders. Conclusions. 18F-fluoride PET-CT identified bone formation, confirmed by histology, in the spine and SI joints of AS patients and demonstrated alterations in bone formation during anti-TNF treatment.

Original languageEnglish
Pages (from-to)631-638
Number of pages8
JournalRheumatology (United Kingdom)
Issue number4
Publication statusPublished - 1 Apr 2018

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