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Objectives: This study aims to establish expert consensus recommendations for clinical information on imaging requests in suspected/known axial spondyloarthritis (axSpA), focusing on enhancing diagnostic clarity and patient care through guidelines., Materials and Methods: A specialised task force was formed, comprising 7 radiologists, 11 rheumatologists from the Assessment of Spondyloarthritis International Society (ASAS) and a patient representative. Using the Delphi method, two rounds of surveys were conducted among ASAS members. These surveys aimed to identify critical elements for imaging referrals and to refine these elements for practical application. The task force deliberated on the survey outcomes and proposed a set of recommendations, which were then presented to the ASAS community for a decisive vote., Results: The collaborative effort resulted in a set of six detailed recommendations for clinicians involved in requesting imaging for patients with suspected or known axSpA. These recommendations cover crucial areas, including clinical features indicative of axSpA, clinical features, mechanical factors, past imaging data, potential contraindications for specific imaging modalities or contrast media and detailed reasons for the examination, including differential diagnoses. Garnering support from 73% of voting ASAS members, these recommendations represent a consensus on optimising imaging request protocols in axSpA., Conclusion: The ASAS recommendations offer comprehensive guidance for rheumatologists in requesting imaging for axSpA, aiming to standardise requesting practices. By improving the precision and relevance of imaging requests, these guidelines should enhance the clinical impact of radiology reports, facilitate accurate diagnosis and consequently improve the management of patients with axSpA., Competing Interests: Competing interests: TD: speakers bureau: Canon MS, Lilly, MSD, Novartis, Pfizer and UCB; consultant: Lilly; grant/research support: Canon MS. CG: speakers bureau: Boehringer Ingelheim. VN-C: has received speakers fees from AbbVie, Eli Lilly, Fresenius Kabi, Janssen, MSD, Novartis, Pfizer, UCB Pharma; consultant of AbbVie, Eli Lilly, MSD, Novartis, Pfizer, UCB Pharma; grant/research support from AbbVie and Novartis. IE: speakers bureau: AbbVie, Novartis. HH: speakers bureau: AbbVie, MSD, Janssen, Roche, Sobi and Pfizer, consultant of Roche, Boehringer Ingelheim, Janssen, MSD, AbbVie, Novartis and Sobi. PMM: honoraria from AbbVie, BMS, Celgene, Eli Lilly, Galapagos, Janssen, MSD, Novartis, Orphazyme, Pfizer, Roche and UCB, all unrelated to this manuscript, and is supported by the National Institute for Health Research (NIHR), University College London Hospitals (UCLH), Biomedical Research Centre (BRC). WM: speaking: AbbVie, Eli Lilly, Janssen, Novartis, Pfizer, UCB consultant: AbbVie, BMS, Celgene, Eli Lilly, Galapagos, Novartis, Pfizer, UCB grants: AbbVie, Eli Lilly, Novartis, Pfizer, UCB. HM-O: research grants from Janssen, Novartis, Pfizer and UCB, honoraria/speaker fees from AbbVie, Amgen, Celgene, Eli Lilly, Janssen, Moonlake, Novartis, Pfizer, Takeda and UCB. MØ: speaker fees: AbbVie, BMS, Celgene, Eli Lilly, Galapagos, Janssen, MEDAC, Merck, Novartis, Pfizer, Regeneron, Roche, Sanofi and UCB. XB: consultant: AbbVie, BMS, Boehringer Ingelheim, Celgene, Eli Lilly, Galapagos, Gilead, Hospira, Janssen, Merck, Novartis, Novo, Orion, Pfizer, Regeneron, Roche, Sandoz, Sanofi and UCB; grant/research support: AbbVie, Amgen, BMS, Celgene, Eli Lilly, Merck, Novartis and UCB. MRu: speaker fees from and/or advisor for AbbVie, Boehringer Ingelheim, Eli Lilly, Janssen, Novartis, UCB. KGH: speaker fees from Novartis, MSD and Pfizer. Consulting for AbbVie and Calyx. Co-founder of BerlinFlame. SJP: speaking fees from MSD, Pfizer, AbbVie, UCB, Novartis; consulting fees and/or honoraria from AbbVie, UCB, Novartis and research support from AbbVie, MSD and Novartis. MRe: ISS grant; ASAS consultant. RGWL: consultant: Calyx, CARE Arthritis, Image Analysis Group. UW: speaker fees: Novartis, Eli Lilly. AGJ: none for this article. MdH: speaker fees from UBC. FAS: speaker fees: Novartis, Pfizer, AbbVie, Janssen., (© Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ on behalf of EULAR.)

Sacroiliitis is commonly seen in patients with axial spondyloarthritis, in whom timely diagnosis and treatment are crucial to prevent irreversible structural damage. Imaging has a prominent place in the diagnostic process and several new imaging techniques have been examined for this purpose. We present a summary of updated evidence-based practice recommendations for imaging of sacroiliitis. MRI remains the imaging modality of choice for patients with suspected sacroiliitis, using at least four sequences: coronal oblique T1-weighted and fluid-sensitive sequences, a perpendicular axial oblique sequence, and a sequence for optimal evaluation of the bone-cartilage interface. Both active inflammatory and structural lesions should be described in the report, indicating location and extent. Radiography and CT, especially low-dose CT, are reasonable alternatives when MRI is unavailable, as patients are often young. This is particularly true to evaluate structural lesions, at which CT excels. Dual-energy CT with virtual non-calcium images can be used to depict bone marrow edema. Knowledge of normal imaging features in children (e.g., flaring, blurring, or irregular appearance of the articular surface) is essential for interpreting sacroiliac joint MRI in children because these normal processes can simulate disease. CLINICAL RELEVANCE STATEMENT: Sacroiliitis is a potentially debilitating disease if not diagnosed and treated promptly, before structural damage to the sacroiliac joints occurs. Imaging has a prominent place in the diagnostic process. We present a summary of practice recommendations for imaging of sacroiliitis, including several new imaging techniques. KEY POINTS: • MRI is the modality of choice for suspected inflammatory sacroiliitis, including a joint-line-specific sequence for optimal evaluation of the bone-cartilage interface to improve detection of erosions. • Radiography and CT (especially low-dose CT) are reasonable alternatives when MRI is unavailable. • Knowledge of normal imaging features in children is mandatory for interpretation of MRI of pediatric sacroiliac joints., (© 2024. The Author(s), under exclusive licence to European Society of Radiology.)

Purpose: Assess whether a Retroaortic left renal vein (RLRV) affects vertebral osteophyte formation in the lumbar spine, compared to normal anatomy left renal vein., Methods: We conducted a retrospective case-control study. Computed tomography (CT) scans of individuals with a RLRV (study group) were compared to age- and gender-matched normal anatomy CT scans (control group). L1 to L4 vertebral levels were appreciated for: left renal vein level, osteophyte presence and the aorta-vertebral distance (AVD) at the left renal vein level. Univariate analyses were conducted using Chi-square test and Fisher's test for categorical variables, and Student's t-test for continuous variables. Logistic regression was used for multivariate analyses., Results: A total of 240 patients were included in the study - equally distributed between the study and control groups. Normal anatomy left renal veins traversed the spine only at the L1 and L2 levels. RLRVs traversed the spine in all L1-L4 levels, mostly at the L3 and L2. Osteophyte prevalence at the level of left renal vein was significantly higher in the study group, compared with the control group [OR 2.54, P = 0.01]. Mean AVD was greater in the study group [9.2 mm ±3.6 mm Vs. 3.5 mm ± 2.6 mm, P < 0.001]. Increased AVD was found to be associated with a higher chance of osteophyte presence at the level of the left renal vein [OR 1.282, P = 0.025]., Conclusions: Osteophytes are more prevalent at the level of the RLRV variant compared to the normal anatomy. Furthermore, the RLRV is characterized by a lower lumbar level compared to the normal anatomy., Clinical Relevance Statement: This anatomic variation could assist in further understanding of osteophyte formation., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

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., Competing Interests: Competing interests: RGWL: consulting fees from CARE Arthritis and Image Analysis Group. XB: contract with Novartis; Consulting fees from Amgen, Bristol-Myers Squibb, Chugai, Eli Lilly, Galapagos, Janssen, Merck Sharp & Dohme, Novartis, Pfizer, Roche, Sandoz, Sanofi, and UCB; Payment or honoraria from Amgen, Bristol-Myers Squibb, Chugai, Eli Lilly, Galapagos, Janssen, Merck Sharp & Dohme, Novartis, Pfizer, Roche, Sandoz, Sanofi, and UCB; Meeting support from Eli Lilly, Janssen, Novartis, Pfizer and UCB; Participation on a Data Safety Monitoring Board or Advisory Board: Amgen, Bristol-Myers Squibb, Eli Lilly, Galapagos, Janssen, Merck Sharp & Dohme, Novartis, Pfizer, Roche, Sandoz, Sanofi and UCB; Leadership role: Editorial Board Member of Annals of Rheumatic Diseases, ASAS President, EULAR President Elect. SAB: Royalties from Elsevier. JAC: Consulting fees from AstraZeneca and Covera Health; Participation on a Data Safety Monitoring Board or Advisory Board: Carestream, Image Analysis Group, Image Biopsy Lab; Leadership role: RSNA, ACR, IAOAI. TD: Grants or contracts from Berlin Institute of Health (BIH); Payment or honoraria from Berlinflame, Canon Medical Systems, Janssen, MSD, Novartis, UCB. IE: Payment or honoraria from Lilly, Novartis. KGH: Payment or honoraria from MSD, AbbVie Novartis; Cofounder of BerlinFlame. NH: None declared. JJ: Stock in Exo. LJ: None declared. AGJ: None declared. JMDO'N:– None declared. MR: ISS Seed Grant; Consultant for ASAS. MJT: Consulting fees from GE HealthCare; Meeting support from International Skeletal Society; Leadership role—President-elect International Skeletal Society. WPM: Grants or contracts from Abbvie, BMS, Eli-Lilly, Pfizer, UCB; Consulting fees from Abbvie, Celgene, BMS, Eli-Lilly, Galapagos, Pfizer, UCB; Payment or honoraria from Abbvie, Janssen, Pfizer, Novartis; Leadership role—SPARTAN Board of Directors; Chief Medical Officer, CARE Arthritis., (© Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ on behalf of EULAR.)

Objectives: Reporting diagnostic confidence (DC) in axial spondyloarthritis (axSpA) imaging is recommended by the ASAS guidelines. Our aim was to investigate whether self-reported DC predicts diagnostic accuracy in axSpA imaging using X-ray (XR), computed tomography (CT) and magnetic resonance imaging (MRI)., Methods: We performed a post hoc analysis including 163 patients with low back pain (89 axSpA and 56 non-axSpA). Nine blinded readers with different experience levels [inexperienced (<1 year), semi-experienced (3-8 years) and experienced (>12 years)] scored the sacroiliac joint images for compatibility with axSpA. DC was reported on a scale from 1 (not sure) to 10 (very sure). Mean DC scores and standard deviations were calculated for correct and incorrect responses using XR, CT, MRI, XR+MRI and CT+MRI. Differences in DC were assessed using the Mann-Whitney U test., Results: DC scores were higher for correct axSpA diagnoses and differed significantly between correct and incorrect responses for all modalities (P < 0.001), with a mean DC of 7.1 ± 2.1 and 6.3 ± 2.1 for XR, 8.3 ± 1.8 and 6.7 ± 2.0 for CT, 8.1 ± 1.9 and 6.2 ± 1.9 for MRI, 8.2 ± 1.8 and 6.7 ± 1.8 for XR+MRI and 8.4 ± 1.8 and 6.8 ± 1.8 for CT+MRI, respectively. This was also the case when looking at the results by experience group, except for XR in the inexperienced group., Conclusion: Providing self-reported DC in radiological reports is useful information to predict diagnostic reliability in axSpA imaging., (© The Author(s) 2023. Published by Oxford University Press on behalf of the British Society for Rheumatology.)

Objectives: Scaphoid fractures are usually diagnosed using X-rays, a low-sensitivity modality. Artificial intelligence (AI) using Convolutional Neural Networks (CNNs) has been explored for diagnosing scaphoid fractures in X-rays. The aim of this systematic review and meta-analysis is to evaluate the use of AI for detecting scaphoid fractures on X-rays and analyze its accuracy and usefulness., Materials and Methods: This study followed the guidelines of Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) and PRISMA-Diagnostic Test Accuracy. A literature search was conducted in the PubMed database for original articles published until July 2023. The risk of bias and applicability were evaluated using the QUADAS-2 tool. A bivariate diagnostic random-effects meta-analysis was conducted, and the results were analyzed using the Summary Receiver Operating Characteristic (SROC) curve., Results: Ten studies met the inclusion criteria and were all retrospective. The AI's diagnostic performance for detecting scaphoid fractures ranged from AUC 0.77 to 0.96. Seven studies were included in the meta-analysis, with a total of 3373 images. The meta-analysis pooled sensitivity and specificity were 0.80 and 0.89, respectively. The meta-analysis overall AUC was 0.88. The QUADAS-2 tool found high risk of bias and concerns about applicability in 9 out of 10 studies., Conclusions: The current results of AI's diagnostic performance for detecting scaphoid fractures in X-rays show promise. The results show high overall sensitivity and specificity and a high SROC result. Further research is needed to compare AI's diagnostic performance to human diagnostic performance in a clinical setting., Clinical Relevance Statement: Scaphoid fractures are prone to be missed secondary to assessment with a low sensitivity modality and a high occult fracture rate. AI systems can be beneficial for clinicians and radiologists to facilitate early diagnosis, and avoid missed injuries., Key Points: • Scaphoid fractures are common and some can be easily missed in X-rays. • Artificial intelligence (AI) systems demonstrate high diagnostic performance for the diagnosis of scaphoid fractures in X-rays. • AI systems can be beneficial in diagnosing both obvious and occult scaphoid fractures., (© 2023. The Author(s).)

Objective: Assess the diagnostic utility of repeat sacroiliac joint (SIJ) magnetic resonance imaging (MRI) examinations following an inconclusive initial examination performed for suspected sacroiliitis., Method: Subjects with > 1 SIJ MRI examinations, an inconclusive first scan and at least 6 months interval between scans, were included. All scans were evaluated for the presence of structural/active SIJ lesions as well as any other pathology. Clinical data was extracted from the patients' clinical files, and any missing data was obtained by a telephone interview. Diagnosis and active/structural scores were compared between first and follow-up examinations (t test)., Results: Seventy-one subjects were included in the study, 77.4% females, mean age 41.0 ± 15 years, mean time interval between exams 30.4 ± 25.24 months. Twelve subjects performed > 2 scans. In only two subjects (2.81%), both females, MRI diagnosis changed from inconclusive to definite sacroiliitis. None of the subjects with > 2 scans had evidence of sacroiliitis in any of the following MRI examinations. Significant differences were observed between the scores of active SIJ lesion of the first and follow-up MRI (1.51/1.62, p = 0.02) but not for scores of structural lesions (1.22/1.68, p = 0.2)., Conclusions: Repeat SIJ MRI when the first MRI is inconclusive for sacroiliitis is more valuable in ruling out than in securing diagnosis of sacroiliitis. We suggest that when MRI findings are inconclusive, decision-making should be based on clinical data., (© 2024. The Author(s), under exclusive licence to International Skeletal Society (ISS).)

Background: Traumatic knee injuries are challenging to diagnose accurately through radiography and to a lesser extent, through CT, with fractures sometimes overlooked. Ancillary signs like joint effusion or lipo-hemarthrosis are indicative of fractures, suggesting the need for further imaging. Artificial Intelligence (AI) can automate image analysis, improving diagnostic accuracy and help prioritizing clinically important X-ray or CT studies., Objective: To develop and evaluate an AI algorithm for detecting effusion of any kind in knee X-rays and selected CT images and distinguishing between simple effusion and lipo-hemarthrosis indicative of intra-articular fractures., Methods: This retrospective study analyzed post traumatic knee imaging from January 2016 to February 2023, categorizing images into lipo-hemarthrosis, simple effusion, or normal. It utilized the FishNet-150 algorithm for image classification, with class activation maps highlighting decision-influential regions. The AI's diagnostic accuracy was validated against a gold standard, based on the evaluations made by a radiologist with at least four years of experience., Results: Analysis included CT images from 515 patients and X-rays from 637 post traumatic patients, identifying lipo-hemarthrosis, simple effusion, and normal findings. The AI showed an AUC of 0.81 for detecting any effusion, 0.78 for simple effusion, and 0.83 for lipo-hemarthrosis in X-rays; and 0.89, 0.89, and 0.91, respectively, in CTs., Conclusion: The AI algorithm effectively detects knee effusion and differentiates between simple effusion and lipo-hemarthrosis in post-traumatic patients for both X-rays and selected CT images further studies are needed to validate these results., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

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., (© RSNA, 2024 See also the editorial by Gandikota in this issue.)

Objective: To develop a reference image atlas for the Outcome Measures in Rheumatology whole-body MRI scoring system for inflammation in peripheral joints and entheses (OMERACT MRI-WIPE) of the knee region., Methods: Image examples of each pathology, location and grade, were collected and discussed at web-based, interactive meetings within the OMERACT MRI in Arthritis Working Group. Subsequently, reference images were selected by consensus., Results: Reference images for each grade, pathology and location are depicted, along with definitions, reader rules and recommended MRI-sequences., Conclusion: The atlas guides scoring whole-body MRIs for inflammation in joints and entheses of the knee region according to MRI-WIPE methodology in clinical trials and cohorts., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Mikkel Østergaard has received research grants from Abbvie, BMS, Merck, Novartis and UCB, consultancy fees from Abbvie, BMS, Celgene, Eli-Lilly, Galapagos, Gilead, Janssen, MEDAC, Merck, Novartis, Pfizer, Sandoz, and UCB Abbvie, BMS, Celgene, Eli-Lilly, Galapagos, Gilead, Janssen, MEDAC, Merck, Novartis, Pfizer, Sandoz, and UCB and speaker fees from Abbvie, BMS, Celgene, Eli-Lilly, Galapagos, Gilead, Janssen, MEDAC, Merck, Novartis, Pfizer, Sandoz, and UCB. Walter P Maksymowych is Chief Medical Officer at CARE Arthritis Limited. Helena Marzo-Ortega has received research grants from Janssen, Novartis, Pfizer and UCB, and speaker fees from AbbVie, Amgen, Biogen, Eli Lilly, Janssen, Novartis, Pfizer, Takeda, UCB. Philip G Conaghan has received consultancy fees from AbbVie, BMS, Eli Lilly, Galapagos, GSK, Janssen, Novartis and Takeda and speaker fees from AbbVie, Eli Lilly and Novartis. Robert GW Lambert has received research grants from Calyx and Care Arthritis, and consultancy fees from Image Analysis Group, Calyx and Care Arthritis. The remaining authors declare no financial interests/personal relationships., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

Objective: To develop a reference image atlas for scoring the hip/pelvis region according to the OMERACT whole-body MRI scoring system for inflammation in peripheral joints and entheses (MRI-WIPE)., Methods: We collected image examples of each pathology, location and grade, discussed them at web-based, interactive meetings and, finally, selected reference images by consensus., Results: Reference images for each grade and location of osteitis, synovitis and soft tissue inflammation are provided, as are definitions, reader rules and recommended MRI-sequences., Conclusion: A reference image atlas was created to guide scoring whole-body MRIs for arthritis and enthesitis in the hip/pelvis region in spondyloarthritis/psoriatic arthritis clinical trials and cohorts., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests Mikkel Østergaard has received research grants from Abbvie, BMS, Merck, Novartis and UCB, consultancy fees from Abbvie, BMS, Celgene, Eli-Lilly, Galapagos, Gilead, Janssen, MEDAC, Merck, Novartis, Pfizer, Sandoz, and UCB Abbvie, BMS, Celgene, Eli-Lilly, Galapagos, Gilead, Janssen, MEDAC, Merck, Novartis, Pfizer, Sandoz, and UCB and speaker fees from Abbvie, BMS, Celgene, Eli-Lilly, Galapagos, Gilead, Janssen, MEDAC, Merck, Novartis, Pfizer, Sandoz, and UCB. Robert GW Lambert has received research grants from Calyx and Care Arthritis, and consultancy fees from Image Analysis Group, Calyx and Care Arthritis. Walter P Maksymowych is Chief Medical Officer at CARE Arthritis Limited. Helena Marzo-Ortega has received research grants from Janssen, Novartis, Pfizer and UCB, and speaker fees from AbbVie, Amgen, Biogen, Eli Lilly, Janssen, Novartis, Pfizer, Takeda, UCB. Philip G Conaghan has received consultancy fees from AbbVie, BMS, Eli Lilly, Galapagos, GSK, Janssen, Novartis and Takeda and speaker fees from AbbVie, Eli Lilly and Novartis. The remaining authors declare no financial interests/personal relationships., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Objective: Reliable interpretation of imaging findings is essential for the diagnosis of axial spondyloarthritis (axSpA) and requires a high level of experience. We investigated experience-dependent differences in diagnostic accuracies using X-ray (XR), MRI and CT., Methods: This post hoc analysis included 163 subjects with low back pain. Eighty-nine patients had axSpA, and 74 patients had other conditions (mechanical, degenerative or non-specific low back pain). Final diagnoses were established by an experienced rheumatologist before the reading sessions. Nine blinded readers (divided into three groups with different levels of experience) scored the XR, CT and MRI of the sacroiliac joints for the presence versus absence of axSpA. Parameters for diagnostic performance were calculated using contingency tables. Differences in diagnostic performance between the reader groups were assessed using the McNemar test. Inter-rater reliability was assessed using Fleiss kappa., Results: Diagnostic performance was highest for the most experienced reader group, except for XR. In the inexperienced and semi-experienced group, diagnostic performance was highest for CT&MRI (78.5% and 85.3%, respectively). In the experienced group, MRI showed the highest performance (85.9%). The greatest difference in diagnostic performance was found for MRI between the inexperienced and experienced group (76.1% vs 85.9%, p=0.001). Inter-rater agreement was best for CT in the experienced group with κ=0.87., Conclusion: Differences exist in the learnability of the imaging modalities for axSpA diagnosis. MRI requires more experience, while CT is more suitable for inexperienced radiologists. However, diagnosis relies on both clinical and imaging information., Competing Interests: Competing interests: KZ reports funding (research grant) from the Assessment of Spondyloarthritis international Society (ASAS) during the conduct of this study. IE reports personal fees from AbbVie, Elli Lili and Novartis. RB reports personal fees from AstraZeneca, Galapagos, GlaxoSmithKline, Medac and Novartis. HH reports grants from Sobi and personal fees from AbbVie, Novartis, Pfizer, Roche and UCB outside the submitted work. JR is participant in the BIH-Charité Clinician Scientist Programme funded by the Charité—Universitätsmedizin Berlin and the Berlin Institute of Health. FP reports grants and personal fees from Novartis, Lilly and UCB, as well as personal fees from AbbVie, Amgen, BMS, Hexal, Janssen, MSD, Pfizer and Roche. K-GAH reports personal fees from AbbVie, MSD, Pfizer and Novartis, he is also the co-founder of BerlinFlame. DP reports grants and personal fees from AbbVie, Eli Lilly, MSD, Novartis and Pfizer and personal fees from Bristol-Myers Squibb, Roche, UCB, Biocad, GlaxoSmithKline and Gilead outside the submitted work. TD reports personal fees from MSD, Novartis and Eli Lilly and reports funding from the Berlin Institute of Health (BIH) during the conduct of this study. STU reports funding from BIH during the conduct of this study (Junior Digital Clinician Scientist Program). All other authors report no funding., (© Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: The Spondyloarthritis Research Consortium of Canada (SPARCC) developers have created web-based calibration modules for the SPARCC MRI sacroiliac joint (SIJ) scoring methods. We aimed to test the impact of applying these e-modules on the feasibility and reliability of these methods., Methods: The SPARCC-SIJ RETIC e-modules contain cases with baseline and follow-up scans and an online scoring interface. Visual real-time feedback regarding concordance/discordance of scoring with expert readers is provided by a colour-coding scheme. Reliability is assessed in real time by intraclass correlation coefficient (ICC), cases being scored until ICC targets are attained. Participating readers (n=17) from the EuroSpA Imaging project were randomised to one of two reader calibration strategies that each comprised three stages. Baseline and follow-up scans from 25 cases were scored after each stage was completed. Reliability was compared with a SPARCC developer, and the System Usability Scale (SUS) assessed feasibility., Results: The reliability of readers for scoring bone marrow oedema was high after the first stage of calibration, and only minor improvement was noted following the use of the inflammation module. Greater enhancement of reader reliability was evident after the use of the structural module and was most consistently evident for the scoring of erosion (ICC status/change: stage 1 (0.42/0.20) to stage 3 (0.50/0.38)) and backfill (ICC status/change: stage 1 (0.51/0.19) to stage 3 (0.69/0.41)). The feasibility of both e-modules was evident by high SUS scores., Conclusion: The SPARCC-SIJ RETIC e-modules are feasible, effective knowledge transfer tools, and their use is recommended before using the SPARCC methods for clinical research and tria., Competing Interests: Competing interests: WM has received honoraria/consulting fees from AbbVie, BMS, Boehringer Ingelheim, Celgene, Eli Lilly, Galapagos, Janssen, Novartis, Pfizer and UCB Pharma; research grants from AbbVie, Pfizer and UCB Pharma; and educational grants from AbbVie, Janssen, Novartis and Pfizer. WM is the Chief Medical Officer for CARE ARTHRITIS. MØ has received research grants from AbbVie, BMS, Merck, Novartis and UCB and speaker and/or consultancy fees from AbbVie, BMS, Boehringer Ingelheim, Celgene, Eli Lilly, Galapagos, Gilead, Hospira, Janssen, MEDAC, Merck, Novartis, Novo, Orion, Pfizer, Regeneron, Roche, Sandoz, Sanofi and UCB. RM received honoraria for lectures or presentations from AbbVie, Eli Lilly, Janssen, Gilead and Pfizer. BM received travel expenditures, honoraria for lectures or presentations from AbbVie, Janssen, Novartis and Pfizer. MJN has received honoraria for travel expenditures, lectures or presentations from AbbVie, Eli Lilly, Janssen, Novartis, Pfizer and UCB. MdH received honoraria for presentations from UCB. RM received honoraria for presentations from UCB., (© Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Introduction: MRI is commonly used to evaluate medial tibial stress syndrome (MTSS), based on grading assessments developed in civilian populations. When MTSS represents stress fracture, rest is required to allow for bone remodelling to occur. False positive evaluations can lead to unnecessary recruit attrition., Methods: Thirty randomly selected new recruits to a special forces training unit underwent MRI of their tibias using the T2-Dixon sequence at the onset of training. Evaluation was according to the Fredericson MTSS grading system. Prior to undergoing MRI, anthropomorphic measurements, a survey of sports history and an orthopaedic examination of subject tibias were performed. Orthopaedic follow-up was through 11 weeks of training., Results: Medial periosteal oedema without the presence of bone marrow oedema, corresponding to a grade 1 stress reaction, was present on MRI in 10 recruits (17 tibias). In only one case did the periosteal oedema include the posterior aspect of the medial cortex where medial tibial stress fractures usually occur. Tibial tenderness was present in seven tibias on examination done just prior to the MRI studies, but none were symptomatic and only one had periosteal oedema present on MRI, but without anatomical correlation between the site of the tenderness and the periosteal oedema. During subsequent training, five tibias in four recruits developed pain and tenderness. Two had periosteal oedema in their prior MRIs, but the location did not coincide anatomically with that of the tibial tenderness. The time from stopping sports before induction and the presence of periosteal oedema was not significant., Conclusion: Periosteal oedema, one of the hallmarks used in MRI grading systems to evaluate MTSS, was found to have a 37.7% false positive rate for anatomically corresponding tibial tenderness at the time of the examination and during subsequent training, indicating the grading systems' low utility for the military., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2024. No commercial re-use. See rights and permissions. Published by BMJ.)