Reporting Sacroiliac Joint Imaging Performed for Known or Suspected Axial Spondyloarthritis: Assessment of SpondyloArthritis International Society Recommendations.

Whereas previous projects attempted to standardize imaging in patients with axial spondyloarthritis (axSpA), few studies have been published about the need for specific details regarding the image acquisition and lesions that may be less familiar to general radiologists. This work reports consensus recommendations developed by the Assessment of SpondyloArthritis International Society (ASAS) that aim to standardize the imaging reports in patients suspected of having or with known axSpA. A task force consisting of radiologists and rheumatologists from ASAS and one patient representative formulated two surveys that were completed by ASAS members. The results of these surveys led to the development of 10 recommendations that were endorsed by 73% (43 of 59) of ASAS members. The recommendations are targeted to the radiologist and include best practices for the inclusion of clinical information, technical details, image quality, and imaging findings in radiology reports. These recommendations also emphasize that imaging findings that indicate differential diagnoses and referral suggestions should be included in the concluding section of the radiology report. With these recommendations, ASAS aims to improve the diagnostic process and care for patients suspected of having or with known axSpA.

Bimekizumab treatment in patients with active axial spondyloarthritis: 52-week efficacy and safety from the randomised parallel phase 3 BE MOBILE 1 and BE MOBILE 2 studies.

OBJECTIVES: Bimekizumab (BKZ), a monoclonal IgG1 antibody that selectively inhibits interleukin (IL)-17F in addition to IL-17A, has demonstrated superior efficacy versus placebo in patients with non-radiographic (nr-) and radiographic (r-) axial spondyloarthritis (axSpA) at Week 16. Here, the objective is to report the efficacy and safety of BKZ at Week 52. METHODS: BE MOBILE 1 (nr-axSpA; NCT03928704) and BE MOBILE 2 (r-axSpA; NCT03928743) comprised a 16-week, double-blind, placebo-controlled period, then a 36-week maintenance period. From Week 16, all patients received subcutaneous BKZ 160 mg every 4 weeks. RESULTS: Improvements versus placebo in Assessment of SpondyloArthritis International Society ≥40% response (primary endpoint), Ankylosing Spondylitis Disease Activity Score, high-sensitivity C-reactive protein levels and MRI inflammation of the sacroiliac joints/spine at Week 16 were sustained to Week 52 in BKZ-randomised patients. At Week 52, responses of patients switching from placebo to BKZ at Week 16 were comparable to BKZ-randomised patients. At Week 52, ≥1 treatment-emergent adverse events (TEAEs) were reported in 183 (75.0%) and 249 (75.5%) patients with nr-axSpA and r-axSpA, respectively. Serious TEAEs occurred in 9 (3.7%) patients with nr-axSpA and 20 (6.1%) patients with r-axSpA. Oral candidiasis was the most frequent fungal infection (nr-axSpA: 18 (7.4%); r-axSpA: 20 (6.1%)). Uveitis occurred in three (1.2%) and seven (2.1%) patients with nr-axSpA and r-axSpA, and inflammatory bowel disease in two (0.8%) and three (0.9%). CONCLUSIONS: At Week 52, dual inhibition of IL-17A and IL-17F with BKZ resulted in sustained efficacy across the axSpA spectrum; the safety profile was consistent with the known safety of BKZ. TRIAL REGISTRATION NUMBER: NCT03928704; NCT03928743.

Development of international consensus on a standardised image acquisition protocol for diagnostic evaluation of the sacroiliac joints by MRI: an ASAS-SPARTAN collaboration.

BACKGROUND: A range of sacroiliac joint (SIJ) MRI protocols are used in clinical practice but not all were specifically designed for diagnostic ascertainment. This can be confusing and no standard diagnostic SIJ MRI protocol is currently accepted worldwide. OBJECTIVE: To develop a standardised MRI image acquisition protocol (IAP) for diagnostic ascertainment of sacroiliitis. METHODS: 13 radiologist members of Assessment of SpondyloArthritis International Society (ASAS) and the SpondyloArthritis Research and Treatment Network (SPARTAN) plus two rheumatologists participated in a consensus exercise. A draft IAP was circulated with background information and online examples. Feedback on all issues was tabulated and recirculated. The remaining points of contention were resolved and the revised IAP was presented to the entire ASAS membership. RESULTS: A minimum four-sequence IAP is recommended for diagnostic ascertainment of sacroiliitis and its differential diagnoses meeting the following requirements. Three semicoronal sequences, parallel to the dorsal cortex of the S2 vertebral body, should include sequences sensitive for detection of (1) changes in fat signal and structural damage with T1-weighting; (2) active inflammation, being T2-weighted with fat suppression; (3) bone erosion optimally depicting the bone-cartilage interface of the articular surface and (4) a semiaxial sequence sensitive for detection of inflammation. The IAP was approved at the 2022 ASAS annual meeting with 91% of the membership in favour. CONCLUSION: A standardised IAP for SIJ MRI for diagnostic ascertainment of sacroiliitis is recommended and should be composed of at least four sequences that include imaging in two planes and optimally visualise inflammation, structural damage and the bone-cartilage interface.

Thresholds for unacceptable work state in radiographic axial Spondyloarthritis of four presenteeism and two clinical outcome measurement instruments.

OBJECTIVES: To a) identify threshold values of presenteeism measurement instruments that reflect unacceptable work state in employed r-axSpA patients; b) determine whether those thresholds accurately predict future adverse work outcomes (AWO) (sick leave or short/long-term disability); c) evaluate the performance of traditional health-outcomes for r-axSpA; d) explore whether thresholds are stable across contextual factors. METHODS: Data from the multinational AS-PROSE study was used. Thresholds to determine whether patients consider themselves in an 'unacceptable work state' were calculated at baseline for four instruments assessing presenteeism and two health-outcomes specific for r-axSpA. Different approaches derived from the receiver operating characteristic methodology were used. Validity of the optimal thresholds was tested across contextual factors and for predicting future AWO over 12 months. RESULTS: Of 366 working patients, 15% reported an unacceptable work state; 6% experienced at least one AWO in 12 months. Optimal thresholds were: WPAI-presenteeism ≥40 (AUC 0.85), QQ-method <97 (0.76), WALS ≥0.75 (AUC 0.87), WLQ-25 ≥ 29 (AUC 0.85). BASDAI and BASFI performed similarly to the presenteeism instruments: ≥4.7 (AUC 0.82) and ≥3.5 (AUC 0.79), respectively. Thresholds for WALS and WLQ-25 were stable across contextual factors, while for all other instruments they overestimated unacceptable work state in lower educated persons. Proposed thresholds could also predict future AWO, although with lower performance, especially for QQ-method, BASDAI and BASFI. CONCLUSIONS: Thresholds of measurement instruments for presenteeism and health status to identify unacceptable work state have been established. These thresholds can help in daily clinical practice to provide work related support to r-axSpA patients at risk for AWO.

Spinal Lesions in Axial Psoriatic Disease: How Should They Be Identified and Quantified by Magnetic Resonance Imaging?

Proper assessment of patients with psoriatic arthritis (PsA) requires assessment of all disease domains, including axial disease. Magnetic resonance imaging (MRI) is the method of choice for evaluating axial involvement in PsA. When assessing patients with PsA for spinal involvement, it is important to assess both vertebral body lesions and posterolateral lesions, such as inflammation in facet joints and costovertebral joints, and enthesitis at spinous and transverse processes. The Canada-Denmark (CanDen) assessment system for spine MRIs is the preferred method for detailed evaluation of inflammation and structural damage at various anatomical locations in the spine, and it is reproducible and sensitive to change. The Assessment of Spondyloarthritis international Society (ASAS) has recently published MRI definitions of inflammatory and structural lesions in the spine, incorporating the CanDen definitions of spinal lesions on MRI. Applying the ASAS definitions and the CanDen assessment system in clinical practice and trials is recommended. Ongoing research/studies, not least the Axial Involvement in Psoriatic Arthritis (AXIS) study, may provide a data-driven definition of axial involvement in PsA. Ongoing research is expected to further improve and validate assessment tools for axial PsA and to provide a much-needed data-driven consensus-based definition of axial involvement in PsA.

Erosions on T1-Weighted Magnetic Resonance Imaging Versus Radiography of Sacroiliac Joints in Recent-Onset Axial Spondyloarthritis: 2-Year Data (EMBARK Trial and DESIR Cohort).

OBJECTIVE: (1) To compare the capacity to detect sacroiliac joint (SIJ) erosions and baseline-to-week 104 change in erosions between magnetic resonance imaging (MRI) and radiographs in recent-onset axial spondyloarthritis (axSpA); and (2) to compare treatment-discriminatory capacities of MRI and radiographic scores for erosion detection in patients receiving etanercept in the Effect of Etanercept on Symptoms and Objective Inflammation in Nonradiographic axSpA (EMBARK) trial vs controls in the DESIR (Devenir des Spondylarthropathies Indifférenciées Récentes) cohort. METHODS: Anonymized SIJ MRI and radiographs were assessed at patient and joint surface levels. Three readers evaluated MRI; 3 different readers evaluated radiographs. Final scores for comparison of radiographs and MRI for detection of erosions were assigned based on agreement of ≥ 2 of 3 readers' assessments. RESULTS: At baseline, discordance in erosion detection between imaging methods was more frequent for MRI erosions in the absence of radiographic erosions (48/224 [21.4%] patients) than for radiographic erosions in the absence of MRI erosions (14/224 [6.3%] patients; P < 0.001). After 104 weeks, a decrease in erosions was observed on MRI but not radiographs in 49/221 (22.2%) patients, and on radiographs but not MRI in 6/221 (2.7%) patients (P < 0.001). In the treatment-discriminant capacity analysis, the largest standardized differences between etanercept and control cohorts at week 104 were changes in Spondyloarthritis Research Consortium of Canada MRI erosion discrete score, changes in erosion average score, and meeting the modified New York criteria on radiographs, with unadjusted/adjusted Hedges G effect sizes of 0.40/0.50, 0.40/0.56, and 0.40/0.43, respectively. CONCLUSION: In recent-onset axSpA, SIJ erosions and erosion change were observed more frequently on MRI than radiography. The significance of interval improvement of MRI erosions warrants further research. [ClinicalTrials.gov: NCT01258738, NCT01648907].

Effect of online training on the reliability of assessing sacroiliac joint radiographs in axial spondyloarthritis - a randomized, controlled study.

OBJECTIVE: Radiographic assessment of sacroiliac joints (SIJs) according to the modified New York (mNY) criteria is key in classification of axSpA but has moderate inter-reader agreement. We aimed to investigate the reliability improvements scoring SIJ radiographs after applying an online real-time iterative calibration (RETIC) module, in addition to a slideshow and video alone. METHODS: Nineteen readers, randomized to 2 groups (A/B), completed 3 calibration steps: I) review of manuscripts, II) review of slideshow and video and group A completed RETIC, III) re-review of slideshow+video and group B completed RETIC . The RETIC module gave instant feedback on reader's gradings and continued until predefined reliability (kappa) targets for mNY positivity/negativity were met. Each step was followed by scoring different batches of 25 radiographs (Exercises I-III). Agreement (kappa) with an expert radiologist was assessed for mNY+/mNY- and individual lesions. Improvements by training strategies were tested by linear mixed models. RESULTS: In exercises I/II/III, mNY kappas were 0.61/0.76/0.84 in group A, and 0.70/0.68/0.86 in group B, respectively, i.e. increasing, mainly after RETIC completion. Improvements were observed for both grading mNY+/mNY- and for individual pathologies, both in experienced and, particularly, inexperienced readers. Completion of the RETIC module in addition to slideshow and video caused a significant kappa increase of 0.17 (CI: 0.07-0.27, P=0.002) for mNY+/mNY- grading, while completion of slideshow and video alone did not (0.0; CI -0.10-+0.10, P=0.99). CONCLUSION: Agreement on scoring radiographs according to the mNY criteria significantly improved when adding an online RETIC module, but not by slideshow and video alone.

Evidence in support of the bone marrow as the primary lesion in axial spondyloarthritis.

PURPOSE OF REVIEW: Over the past several decades, the concept that the primary lesion accounting for the development of axSpA is an enthesopathy has been widely accepted. However, the hallmark abnormality of axSpA occurs in the sacroiliac joint at the interface of cartilage and bone at a location remote from any anatomical enthesis. Both imaging and histopathological data from the sacroiliac joint point to immunopathogenetic events in the bone marrow as being of primary importance. Here, we discuss new developments in our understanding of immune events in the bone marrow relevant to axSpA that reinforce the need for a change in our conceptual paradigm for the pathogenesis of axSpA. RECENT FINDINGS: Human spinal enthesis samples contain myeloperoxidase-expressing cells, a marker of neutrophils, and mucosal-associated invariant T cells in the perientheseal bone marrow, which may be activated by stromal cells and circulating microbial products to express IL-17A and IL-17F and tumor necrosis factor (TNF). Evaluation of transcriptomes of monocytes from patients with axSpA demonstrates a lipopolysaccharide/TNF signature characterized by the expression of genes associated with granulocytopoietic bone marrow cells. This neutrophil-like phenotype is more evident in established and more severe axSpA and may be activated by microbial products from the gut. A similar expansion of granulocyte-monocyte progenitor-driven hematopoiesis occurs in the SKG mouse driven by granulocyte-macrophage colony-stimulating factor. Mesenchymal stem cells (MSCs) from ankylosing spondylitis patients are more likely to exhibit osteogenic differentiation than MSCs from healthy donors, which may be mediated by the formation of specific clusters of transcriptional factors, super enhancers, regulated by axSpA-associated single nucleotide polymorphisms located mostly in noncoding regions. TNF-α may enhance directional migration of AS-MSC compared with MSC from healthy controls from the bone marrow to entheseal soft tissue, which is mediated by increased expression of engulfment and cell motility protein 1 (ELMO1). TNF and IL-17A display differential effects on adipogenesis and osteogenesis of MSC in perientheseal bone marrow and soft tissue. SUMMARY: Bone marrow has the capacity to undergo rapid adaptation in terms of cell composition, differentiation, and immune function, resulting in inflammation and osteogenesis in axSpA.

Upadacitinib for the treatment of active non-radiographic axial spondyloarthritis (SELECT-AXIS 2): a randomised, double-blind, placebo-controlled, phase 3 trial.

BACKGROUND: Upadacitinib, a Janus kinase inhibitor, has been shown to be effective in patients with ankylosing spondylitis. We aimed to assess the efficacy and safety of upadacitinib in non-radiographic axial spondyloarthritis. METHODS: The SELECT-AXIS 2 non-radiographic axial spondyloarthritis study was a multicentre, randomised, double-blind, placebo-controlled, phase 3 trial at 113 sites across 23 countries (Argentina, Australia, Belgium, Brazil, Bulgaria, Canada, China, Czech Republic, France, Germany, Hungary, Israel, Japan, Mexico, Poland, Russia, Slovakia, South Korea, Spain, Taiwan, Turkey, Ukraine, and the USA). Eligible adults had active non-radiographic axial spondyloarthritis, with objective signs of inflammation based on MRI or elevated C-reactive protein and an inadequate response to non-steroidal anti-inflammatory drugs. Patients were randomly assigned (1:1) to receive oral upadacitinib 15 mg once daily or placebo using interactive response technology. Random treatment assignment was stratified by MRI inflammation in the sacroiliac joints and screening high-sensitivity C-reactive protein status (MRI-positive and C-reactive protein-positive, MRI-positive and C-reactive protein-negative, and MRI-negative and C-reactive protein-positive) and previous exposure to biologic disease-modifying antirheumatic drugs (yes vs no). Treatment assignment was masked from patients, investigators, study site personnel, and the study sponsor. The primary endpoint was the proportion of patients with an Assessment of SpondyloArthritis international Society 40 (ASAS40) response at week 14. Analyses were performed on the full analysis set of patients, who underwent random allocation and received at least one dose of study drug. This trial is registered with ClinicalTrials.gov, NCT04169373. FINDINGS: Between Nov 26, 2019, and May 20, 2021, 314 patients with active non-radiographic axial spondyloarthritis were enrolled into the study, and 313 received study drug (156 in the upadacitinib group and 157 in the placebo group); 295 (94%) patients (145 in the upadacitinib group and 150 in the placebo group) received treatment for the full 14 weeks. A significantly higher ASAS40 response rate was achieved with upadacitinib compared with placebo at week 14 (70 [45%] of 156 patients vs 35 [23%] of 157 patients; p<0·0001; treatment difference 22%, 95% CI 12-32). The rate of adverse events up to week 14 was similar in the upadacitinib group (75 [48%] of 156 patients) and placebo group (72 [46%] of 157 patients). Serious adverse events and adverse events leading to discontinuation of study drug occurred in four (3%) of 156 patients in the upadacitinib group and two (1%) of 157 patients in the placebo group. Few patients had serious infections or herpes zoster in either treatment group (each event occurred in two [1%] of 156 patients in the upadacitinib group and one [1%] of 157 patients in the placebo group). Five (3%) of 156 patients in the upadacitinib group had neutropenia; no events of neutropenia occurred in the placebo group. No opportunistic infections, malignancies, major adverse cardiovascular events, venous thromboembolic events, or deaths were reported with upadacitinib treatment. INTERPRETATION: Upadacitinib significantly improved the signs and symptoms of non-radiographic axial spondyloarthritis compared with placebo at week 14. These findings support the potential of upadacitinib as a new therapeutic option in patients with active non-radiographic axial spondyloarthritis. FUNDING: AbbVie.

Instrument selection for the ASAS core outcome set for axial spondyloarthritis.

OBJECTIVES: To define the instruments for the Assessment of SpondyloArthritis international Society-Outcomes Measures in Rheumatology (ASAS-OMERACT) core domain set for axial spondyloarthritis (axSpA). METHODS: An international working group representing key stakeholders selected the core outcome instruments following a predefined process: (1) identifying candidate instruments using a systematic literature review; (2) reducing the list of candidate instruments by the working group, (3) assessing the instruments' psychometric properties following OMERACT filter 2.2, (4) selection of the core instruments by the working group and (5) voting and endorsement by ASAS. RESULTS: The updated core set for axSpA includes seven instruments for the domains that are mandatory for all trials: Ankylosing Spondylitis Disease Activity Score and Numerical Rate Scale (NRS) patient global assessment of disease activity, NRS total back pain, average NRS of duration and severity of morning stiffness, NRS fatigue, Bath Ankylosing Spondylitis Function Index and ASAS Health Index. There are 9 additional instruments considered mandatory for disease-modifying antirheumatic drugs (DMARDs) trials: MRI activity Spondyloarthritis Research Consortium of Canada (SPARCC) sacroiliac joints and SPARCC spine, uveitis, inflammatory bowel disease and psoriasis assessed as recommended by ASAS, 44 swollen joint count, Maastricht Ankylosing Spondylitis Enthesitis Score, dactylitis count and modified Stoke Ankylosing Spondylitis Spinal Score. The imaging outcomes are considered mandatory to be included in at least one trial for a drug tested for properties of DMARD. Furthermore, 11 additional instruments were also endorsed by ASAS, which can be used in axSpA trials on top of the core instruments. CONCLUSIONS: The selection of the instruments for the ASAS-OMERACT core domain set completes the update of the core outcome set for axSpA, which should be used in all trials.

Efficacy and safety of bimekizumab in axial spondyloarthritis: results of two parallel phase 3 randomised controlled trials.

OBJECTIVES: Axial spondyloarthritis (axSpA) is a complex disease with diverse manifestations, for which new treatment options are warranted. BE MOBILE 1 (non-radiographic (nr)-axSpA) and BE MOBILE 2 (radiographic axSpA (r-axSpA)) are double-blind, phase 3 trials designed to evaluate efficacy and safety of bimekizumab, a novel dual interleukin (IL)-17A and IL-17F inhibitor, across the axSpA spectrum. METHODS: In parallel 52-week trials, patients with active disease were randomised 1:1 (nr-axSpA) or 2:1 (r-axSpA) to bimekizumab 160 mg every 4 weeks:placebo. From week 16, all patients received bimekizumab 160 mg every 4 weeks. Primary (Assessment of SpondyloArthritis international Society ≥40% improvement (ASAS40)) and secondary endpoints were assessed at week 16. Here, efficacy and treatment-emergent adverse events (TEAEs) are reported up to week 24. RESULTS: 254 patients with nr-axSpA and 332 with r-axSpA were randomised. At week 16, primary (ASAS40, nr-axSpA: 47.7% bimekizumab vs 21.4% placebo; r-axSpA: 44.8% vs 22.5%; p<0.001) and all ranked secondary endpoints were met in both trials. ASAS40 responses were similar across TNFi-naïve and TNFi-inadequate responder patients. Improvements were observed in Ankylosing Spondylitis Disease Activity Score (ASDAS) states and objective measures of inflammation, including high-sensitivity C-reactive protein (hs-CRP) and MRI of the sacroiliac joints and spine. Most frequent TEAEs with bimekizumab (>3%) included nasopharyngitis, upper respiratory tract infection, pharyngitis, diarrhoea, headache and oral candidiasis. More fungal infections (all localised) were observed with bimekizumab vs placebo; no major adverse cardiovascular events (MACE) or active tuberculosis were reported. Incidence of uveitis and adjudicated inflammatory bowel disease was low. CONCLUSIONS: Dual inhibition of IL-17A and IL-17F with bimekizumab resulted in significant and rapid improvements in efficacy outcomes vs placebo and was well tolerated in patients with nr-axSpA and r-axSpA.

Comparing MRI and conventional radiography for the detection of structural changes indicative of axial spondyloarthritis in the ASAS cohort.

OBJECTIVES: To compare MRI and conventional radiography of SI joints for detection of structural lesions typical for axial spondyloarthritis (axSpA). METHODS: Adult patients from the Assessment of SpondyloArthritis international Society (ASAS) cohort with symptoms suggestive of axSpA and both SI joint MRI and radiographs available for central reading were included. Radiographs were evaluated by three readers according to the modified New York (mNY) criteria grading system. The presence of structural damage on radiographs was defined as fulfilment of the radiographic mNY criterion and, additionally, a lower threshold for sacroiliitis of at least grade 2 unilaterally. MRI scans were assessed for the presence of structural changes indicative of axSpA by seven readers. Diagnostic performance [sensitivity, specificity, positive and negative predictive values (PPV and NPV) and positive and negative likelihood ratios (LR+ and LR-)] of MRI and radiographs (vs rheumatologist's diagnosis of axSpA) were calculated. RESULTS: Overall, 183 patients were included and 135 (73.7%) were diagnosed with axSpA. Structural lesions indicative of axSpA on MRI had sensitivity 38.5%, specificity 91.7%, PPV 92.9%, NPV 34.6%, LR+ 4.62 and LR- 0.67. Sacroiliitis according to the mNY criteria had sensitivity 54.8%, specificity 70.8%, PPV 84.1%, NPV 35.8%, LR+ 1.88 and LR- 0.64. Radiographic sacroiliitis of at least grade 2 unilaterally had sensitivity 65.2%, specificity 50.0%, PPV 78.6%, NPV 33.8%, LR+ 1.30 and LR- 0.69. CONCLUSION: Structural lesions of the SI joint detected by MRI demonstrated better diagnostic performance and better interreader reliability compared with conventional radiography.

Stricter treat-to-target in RA does not result in less radiographic progression: a longitudinal analysis in RA BIODAM.

OBJECTIVES: To investigate whether meticulously following a treat-to-target (T2T)-strategy in daily clinical practice will lead to less radiographic progression in patients with active RA who start (new) DMARD-therapy. METHODS: Patients with RA from 10 countries starting/changing conventional synthetic or biologic DMARDs because of active RA, and in whom treatment intensification according to the T2T principle was pursued, were assessed for disease activity every 3 months for 2 years (RA-BIODAM cohort). The primary outcome was the change in Sharp-van der Heijde (SvdH) score, assessed every 6 months. Per 3-month interval DAS44-T2T could be followed zero, one or two times (in a total of two visits). The relation between T2T intensity and change in SvdH-score was modelled by generalized estimating equations. RESULTS: In total, 511 patients were included [mean (s.d.) age: 56 (13) years; 76% female]. Mean 2-year SvdH progression was 2.2 (4.1) units (median: 1 unit). A stricter application of T2T in a 3-month interval did not reduce progression in the same 6-month interval [parameter estimates (for yes vs no): +0.15 units (95% CI: -0.04, 0.33) for 2 vs 0 visits; and +0.08 units (-0.06; 0.22) for 1 vs 0 visits] nor did it reduce progression in the subsequent 6-month interval. CONCLUSIONS: In this daily practice cohort, following T2T principles more meticulously did not result in less radiographic progression than a somewhat more lenient attitude towards T2T. One possible interpretation of these results is that the intention to apply T2T already suffices and that a more stringent approach does not further improve outcome.

Neural network algorithm for detection of erosions and ankylosis on CT of the sacroiliac joints: multicentre development and validation of diagnostic accuracy.

OBJECTIVES: To evaluate the feasibility and diagnostic accuracy of a deep learning network for detection of structural lesions of sacroiliitis on multicentre pelvic CT scans. METHODS: Pelvic CT scans of 145 patients (81 female, 121 Ghent University/24 Alberta University, 18-87 years old, mean 40 ± 13 years, 2005-2021) with a clinical suspicion of sacroiliitis were retrospectively included. After manual sacroiliac joint (SIJ) segmentation and structural lesion annotation, a U-Net for SIJ segmentation and two separate convolutional neural networks (CNN) for erosion and ankylosis detection were trained. In-training validation and tenfold validation testing (U-Net-n = 10 × 58; CNN-n = 10 × 29) on a test dataset were performed to assess performance on a slice-by-slice and patient level (dice coefficient/accuracy/sensitivity/specificity/positive and negative predictive value/ROC AUC). Patient-level optimisation was applied to increase the performance regarding predefined statistical metrics. Gradient-weighted class activation mapping (Grad-CAM++) heatmap explainability analysis highlighted image parts with statistically important regions for algorithmic decisions. RESULTS: Regarding SIJ segmentation, a dice coefficient of 0.75 was obtained in the test dataset. For slice-by-slice structural lesion detection, a sensitivity/specificity/ROC AUC of 95%/89%/0.92 and 93%/91%/0.91 were obtained in the test dataset for erosion and ankylosis detection, respectively. For patient-level lesion detection after pipeline optimisation for predefined statistical metrics, a sensitivity/specificity of 95%/85% and 82%/97% were obtained for erosion and ankylosis detection, respectively. Grad-CAM++ explainability analysis highlighted cortical edges as focus for pipeline decisions. CONCLUSIONS: An optimised deep learning pipeline, including an explainability analysis, detects structural lesions of sacroiliitis on pelvic CT scans with excellent statistical performance on a slice-by-slice and patient level. CLINICAL RELEVANCE STATEMENT: An optimised deep learning pipeline, including a robust explainability analysis, detects structural lesions of sacroiliitis on pelvic CT scans with excellent statistical metrics on a slice-by-slice and patient level. KEY POINTS: • Structural lesions of sacroiliitis can be detected automatically in pelvic CT scans. • Both automatic segmentation and disease detection yield excellent statistical outcome metrics. • The algorithm takes decisions based on cortical edges, rendering an explainable solution.

Deep Learning Detects Changes Indicative of Axial Spondyloarthritis at MRI of Sacroiliac Joints.

Background MRI is frequently used for early diagnosis of axial spondyloarthritis (axSpA). However, evaluation is time-consuming and requires profound expertise because noninflammatory degenerative changes can mimic axSpA, and early signs may therefore be missed. Deep neural networks could function as assistance for axSpA detection. Purpose To create a deep neural network to detect MRI changes in sacroiliac joints indicative of axSpA. Materials and Methods This retrospective multicenter study included MRI examinations of five cohorts of patients with clinical suspicion of axSpA collected at university and community hospitals between January 2006 and September 2020. Data from four cohorts were used as the training set, and data from one cohort as the external test set. Each MRI examination in the training and test sets was scored by six and seven raters, respectively, for inflammatory changes (bone marrow edema, enthesitis) and structural changes (erosions, sclerosis). A deep learning tool to detect changes indicative of axSpA was developed. First, a neural network to homogenize the images, then a classification network were trained. Performance was evaluated with use of area under the receiver operating characteristic curve (AUC), sensitivity, and specificity. P < .05 was considered indicative of statistically significant difference. Results Overall, 593 patients (mean age, 37 years ± 11 [SD]; 302 women) were studied. Inflammatory and structural changes were found in 197 of 477 patients (41%) and 244 of 477 (51%), respectively, in the training set and 25 of 116 patients (22%) and 26 of 116 (22%) in the test set. The AUCs were 0.94 (95% CI: 0.84, 0.97) for all inflammatory changes, 0.88 (95% CI: 0.80, 0.95) for inflammatory changes fulfilling the Assessment of SpondyloArthritis international Society definition, and 0.89 (95% CI: 0.81, 0.96) for structural changes indicative of axSpA. Sensitivity and specificity on the external test set were 22 of 25 patients (88%) and 65 of 91 patients (71%), respectively, for inflammatory changes and 22 of 26 patients (85%) and 70 of 90 patients (78%) for structural changes. Conclusion Deep neural networks can detect inflammatory or structural changes to the sacroiliac joint indicative of axial spondyloarthritis at MRI. © RSNA, 2022 Online supplemental material is available for this article.

MRI lesions of the spine in patients with axial spondyloarthritis: an update of lesion definitions and validation by the ASAS MRI working group.

OBJECTIVES: Spinal MRI is used to visualise lesions associated with axial spondyloarthritis (axSpA). The ASAS MRI working group (WG) updated and validated the definitions for inflammatory and structural spinal lesions in the context of axSpA. METHODS: After review of the existing literature on all possible types of spinal MRI pathologies in axSpA, the group (12 rheumatologists and two radiologists) consented on the required revisions of lesion definitions compared with the existing nomenclature of 2012. In a second step, using 62 MRI scans from the ASAS classification cohort, the proposed definitions were validated in a multireader campaign by global (absent/present) and detailed (inflammation and structural) lesion assessment at the vertebral corner (VC), vertebral endplate, facet joints, transverse processes, lateral and posterior elements. Intraclass correlation coefficient (ICC) was used for analysis. RESULTS: Revisions were made for both inflammatory (bone marrow oedema, BMO) and structural (fat, erosion, bone spur and ankylosis) lesions, including localisation (central vs lateral), extension (VC vs vertebral endplate) and extent (minimum number of slices needed), while new definitions were suggested for the type of lesion based on lesion maturity (VC monomorphic vs dimorphic). The most reliably assessed lesions were VC fat lesion and VC monomorphic BMO (ICC (mean of all 36 reader pairs/overall 9 readers): 0.91/0.92; 0.70/0.67, respectively. CONCLUSIONS: The lesion definitions for spinal MRI lesions compatible with SpA were updated by consensus and validated by a group of experienced readers. The lesions with the highest frequency and best reliability were fat and monomorphic inflammatory lesions at the VC.

Filgotinib decreases both vertebral body and posterolateral spine inflammation in ankylosing spondylitis: results from the TORTUGA trial.

OBJECTIVES: To assess the effects of filgotinib on inflammatory and structural changes at various spinal locations, based on MRI measures in patients with active AS in the TORTUGA trial. METHODS: In the TORTUGA trial, patients with AS received filgotinib 200 mg (n = 58) or placebo (n = 58) once daily for 12 weeks. In this post hoc analysis, spine MRIs were evaluated using the Canada-Denmark (CANDEN) MRI scoring system to assess changes from baseline to week 12 in total spine and subscores for inflammation, fat, erosion and new bone formation (NBF) at various anatomical locations. Correlations were assessed between CANDEN inflammation and clinical outcomes and Spondyloarthritis Research Consortium of Canada (SPARCC) MRI scores and between baseline CANDEN NBF and baseline BASFI and BASMI scores. RESULTS: MRIs from 47 filgotinib- and 41 placebo-treated patients were evaluated. There were significantly larger reductions with filgotinib vs placebo in total spine inflammation score and most inflammation subscores, including posterolateral elements (costovertebral joints, transverse/spinous processes, soft tissues), facet joints and vertebral bodies. No significant differences were observed for corner or non-corner vertebral body inflammation subscores, spine fat lesion, bone erosion or NBF scores. In the filgotinib group, the change from baseline in the total inflammation score correlated positively with the SPARCC spine score. Baseline NBF scores correlated with baseline BASMI but not BASFI scores. CONCLUSIONS: Compared with placebo, filgotinib treatment was associated with significant reductions in MRI measures of spinal inflammation, including in vertebral bodies, facet joints and posterolateral elements. TRIAL REGISTRATION: ClinicalTrials.gov (https://clinicaltrials.gov), NCT03117270.

Long-term tolerability and efficacy of golimumab in active non-radiographic axial spondyloarthritis: results from open-label extension.

OBJECTIVES: We report the open-label extension (OLE) of the GO-AHEAD study evaluating the long-term efficacy and safety of golimumab (GLM) in patients with non-radiographic axial spondyloarthritis (nr-axSpA). METHODS: Patients [both GLM- and placebo (PBO)-treated in the double-blind phase] received GLM 50 mg every 4 weeks during the OLE (36-week treatment; additional 8-week safety follow-up; GLM/GLM and PBO/GLM groups). All patients who entered and received ≥1 dose of study treatment in the OLE were included in the efficacy and safety analyses. The primary efficacy evaluations were the proportions of patients achieving 20% and 40% improvement in the ASAS criteria (ASAS20 and ASAS40, respectively). Responders' analyses were calculated using a non-responder imputation approach. RESULTS: Of 198 patients randomised, 189/198 (95.5%) entered the OLE; 174/198 patients (87.9%) completed all visits. Although the proportion of responders increased from week 16 to week 52 in the OLE in both GLM/GLM and PBO/GLM groups, the GLM/GLM group had a higher proportion of responders than the PBO/GLM group throughout the OLE from week 16 to week 52 (ASAS20: 71.1% to 83.9% vs 40.0% to 75.0%, respectively; ASAS40: 56.7% to 76.3% vs 23.0% to 59.4%, respectively; ASAS partial remission: 33.0% to 53.8% and 18.0% to 45.8%). In the OLE, the overall incidence of AEs was lower in the GLM/GLM vs PBO/GLM groups (41.9% and 54.2%). CONCLUSIONS: Sustained improvement in clinical efficacy was observed at 52 weeks in patients with nr-axSpA following GLM treatment. GLM was well tolerated and provided substantial long-term benefits to patients with nr-axSpA. TRIAL REGISTRATION: NCT01453725; United States National Library of Medicine clinical trials database; www.clinicaltrials.gov.

Impact of filgotinib on sacroiliac joint magnetic resonance imaging structural lesions at 12 weeks in patients with active ankylosing spondylitis (TORTUGA trial).

OBJECTIVE: To assess the effect of filgotinib, which preferentially inhibits Janus kinase 1 (JAK1), on MRI measures of structural change in the SI joint in patients with active AS in the TORTUGA trial. METHODS: Adults with active AS and inadequate response/intolerance to two or more NSAIDs were randomized 1:1 to filgotinib 200 mg (n = 58) or placebo (n = 58) once daily for 12 weeks. In this post hoc analysis, T1-weighted MRI scans of the SI joint were evaluated by two independent readers using Spondyloarthritis Research Consortium of Canada (SPARCC) Sacroiliac Joint Structural Score (SSS) definitions for erosion, backfill, fat metaplasia and ankylosis. Correlations between SPARCC SSS and improvement in clinical outcomes were also assessed. RESULTS: MRI scans from 87 patients (48 filgotinib, 39 placebo) were evaluated. At baseline there were no notable differences between filgotinib and placebo for any MRI structural lesion types. From baseline to week 12, filgotinib was associated with a significant reduction in SI joint erosion score (P = 0.02) and an increase in backfill score (P = 0.005) vs placebo, with no significant between-group differences for ankylosis (P = 0.46) or fat metaplasia (P = 0.17). At week 12, the change in SPARCC MRI SI joint inflammation scores correlated positively with erosion scores but negatively with backfill scores. CONCLUSION: The significant changes in MRI structural lesions induced by filgotinib in the SI joint by week 12 demonstrate that tissue repair can be observed very soon after starting treatment with a JAK1 preferential inhibitor. This could have prognostic implications for development of ankylosis. TRIAL REGISTRATION: ClinicalTrials.gov, http://clinicaltrials.gov, NCT03117270.

A review of JAK-STAT signalling in the pathogenesis of spondyloarthritis and the role of JAK inhibition.

Spondyloarthritis (SpA) comprises a group of chronic inflammatory diseases with overlapping clinical, genetic and pathophysiological features including back pain, peripheral arthritis, psoriasis, enthesitis and dactylitis. Several cytokines are involved in the pathogenesis of SpA, variously contributing to each clinical manifestation. Many SpA-associated cytokines, including IL-23, IL-17, IL-6, type I/II interferon and tumour necrosis factor signal directly or indirectly via the Janus kinase (JAK)-signal transducer and activator of transcription pathway. JAK signalling also regulates development and maturation of cells of the innate and adaptive immune systems. Accordingly, disruption of this signalling pathway by small molecule oral JAK inhibitors can inhibit signalling implicated in SpA pathogenesis. Herein we discuss the role of JAK signalling in the pathogenesis of SpA and summarize the safety and efficacy of JAK inhibition by reference to relevant SpA clinical trials.