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

STG Bruijnen, NJF Verweij… - …, 2018 - academic.oup.com
STG Bruijnen, NJF Verweij, LM van Duivenvoorde, N Bravenboer, DLP Baeten…
Rheumatology, 2018academic.oup.com
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 …
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.
Oxford University Press