Date: Monday, November 9, 2020
Session Type: Abstract Session
Session Time: 5:00PM-5:50PM
Background/Purpose: The clinical efficacy of TNFi in patients with axSpA is well established but its effect on new bone formation is still unclear. Positron emission tomography (PET) using bone-seeking 18F-Fluoride [18F]F in combination with magnetic resonance imaging ([18F]F/MRI) can depict bone marrow edema (BME) but also shows the quantity of tracer uptake in the late phase of perfusion suggestive of remodeling and osteoblastic activity. We assessed the effect of TNFi on bone remodeling processes in the axial skeleton of r-axSpA patients using [18F]F/MRI prior (baseline, BL) and 4 months after (follow-up, FU) treatment.
Methods: Patients (11 male, 5 female, mean age 38.6±12.0 years) with clinically active AS (BASDAI >4, failure of NSAIDs, no previous biologics) prospectively underwent 3-Tesla and [18F]F PET/MRI (40 minutes after injection of a mean activity of 157 MBq [18F]F). Images of the SIJ (n=16 patients) and the whole spine (n=10 patients) were performed at BL and FU. Three readers (1 for [18F]F/MRI and 2 for conventional MRI) evaluated all images independently and blinded to timepoint allocation. Only lesions on which all readers agreed on were used for further analyses. Inflammation (bone marrow edema, BME), structural lesions (fat deposition (FD), sclerosis, erosions and ankylosis) and focal [18F]F uptake were recorded on the level of SIJ (SIJ-Q) and vertebral quadrants (V-Q), with each SIJ or vertebral body consisting of 4 VQs (superior and inferior sacral and iliac for the SIJ, and superior and inferior, anterior and posterior for the vertebral bodies).
Results: A total of 128 SIJ-Q and 920 VQs were analyzed at both BL and FU. In the SIJs, 75 (58.6%), 120 (93.8%), 69 (53.9%), 99 (77.3%) and 16 (12.5%) SIJ-Q showed BME, FD, sclerosis, erosions and ankylosis, while 111 (86.7%) SIJ-Q showed focal [18F]F-uptake at BL. Association with increased [18F]F-uptake was found most frequently in SIJ-Q with BME (70/75 SIJ-Q, 93.3%), sclerosis (65/69 SIJ-Q, 94.2%) and FD (105/120 SIJ-Q, 87.5%). At FU, 37 SIJ-Q still showed BME (improvement by 50.7%), while almost no changes were observed in chronic lesions. In comparison, improvement of focal [18F]F-uptake was found in all lesion combinations, with improvement of focal [18F]F-lesions associated with BME by 62.9%, with sclerosis by 33.8% and with FD by 22.9% of SIJ-Q.
In the spine, only 41 (4.5%), 61 (6.6%), 14 (1.5%) V-Q showed BME, FD and sclerosis, respectively, while 77 V-Q (8.4%) showed focal [18F]F-uptake. An association to increased [18F]F-uptake was found most frequently with sclerosis (7/14 V-Q, 50%) and FD (25/61 V-Q, 41%). At FU, 12 V-Q still showed BME (improvement by 70.7%), almost no changes were observed for chronic lesions. The largest improvement was found in focal [18F]F-lesions associated with BME 81.8% and with FD by 22.9% of V-Q.
Conclusion: In this first prospective study on whole spine and SIJ [18F]F/MRI in patients with AS, a significant decrease of osteoblastic activity was observed over 4 months of continuous anti-TNF treatment. These data support a short-term effect of anti-TNF treatment on osteoblastic activity, while the long-term effects need to be further studied
To cite this abstract in AMA style:Baraliakos X, Tsiami S, Rischpler C, Bruckmann N, Fendler W, Kirchner J, Herrmann K, Sawicki L, Braun J. Effects of Anti-TNF-therapy on Osteoblastic Activity in Ankylosing Spondylitis – Results from a Prospective Study Using PET-MRI of SIJ and Spine [abstract]. Arthritis Rheumatol. 2020; 72 (suppl 10). https://acrabstracts.org/abstract/effects-of-anti-tnf-therapy-on-osteoblastic-activity-in-ankylosing-spondylitis-results-from-a-prospective-study-using-pet-mri-of-sij-and-spine/. Accessed December 7, 2021.
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