RT Journal Article SR Electronic T1 Hybrid 18F-labeled Fluoride Positron Emission Tomography/Magnetic Resonance (MR) Imaging of the Sacroiliac Joints and the Spine in Patients with Axial Spondyloarthritis: A Pilot Study Exploring the Link of MR Bone Pathologies and Increased Osteoblastic Activity JF The Journal of Rheumatology JO J Rheumatol FD The Journal of Rheumatology SP 1631 OP 1637 DO 10.3899/jrheum.150250 VO 42 IS 9 A1 Christian Buchbender A1 Benedikt Ostendorf A1 Verena Ruhlmann A1 Philipp Heusch A1 Falk Miese A1 Karsten Beiderwellen A1 Matthias Schneider A1 Juergen Braun A1 Gerald Antoch A1 Xenofon Baraliakos YR 2015 UL http://www.jrheum.org/content/42/9/1631.abstract AB Objective. The biologically active molecule used in positron emission tomography (PET) for depiction of osteoblastic activity is 18F-labeled fluoride (18F-F). We examined whether inflammatory or chronic changes on magnetic resonance imaging (MRI) in the sacroiliac joints (SIJ) and the spines of patients with active ankylosing spondylitis (AS) are linked to osteoblastic activity, assessed by PET/MRI.Methods. Thirteen patients with AS (mean age 37.8 ± 11.4 yrs, Bath AS Disease Activity Index > 4, no anti-TNF treatment) underwent 3-Tesla whole-spine and SIJ PET/MRI. Two independent readers recorded pathologic changes related to vertebral (VQ) or SIJ quadrants (SQ). Final scores were based on reader agreement.Results. A total of 104 SQ and 1196 VQ were examined. In SIJ, bone marrow edema (BME) was seen in 44.2%, fat deposition (FD) in 42.3%, and 18F-F in 46.2% SQ. BME alone was associated with 18F-F in 78.6% and FD alone in only 7.7% SQ, while the combination BME/FD was associated with 18F-F in 72.2% SQ. Erosions, sclerosis, and ankylosis alone were rarely associated with 18F-F. In the spine, BME alone was seen in 9.9%, FD in 18.2%, and 18F-F in 5.4% VQ. BME alone was associated with 18F-F in 14.3% and FD alone in 8.7% VQ, while the combination BME/FD was associated with 18F-F in 40.6% VQ.Conclusion. In this study of hybrid 18F-F PET/MRI of patients with active AS, we show that BME rather than chronic changes is associated with osteoblastic activity, while the combination of BME and FD showed the highest 18F-F uptake. The use of PET/MRI in prediction of future syndesmophyte formation in AS needs further exploration in prospective studies.