Magnetic Resonance Imaging of the Sacroiliac Joints Indicating Sacroiliitis According to the Assessment of SpondyloArthritis international Society Definition in Healthy Individuals, Runners, and Women With Postpartum Back Pain

Axial Imaging in Spondyloarthritis

Imaging plays a crucial role in diagnosing and forecasting treatment outcomes in axial spondyloarthritis. Conventional radiography may overlook patients in the initial stages of the disease, while MRI is sensitive in identifying inflammation early on. Computed tomography reliably detects structural abnormalities. Practicing rheumatologists must possess a fundamental understanding of interpreting both active inflammatory and structural lesions in axial spondyloarthritis.

The role of sacro-iliac joint magnetic resonance imaging in the diagnosis of axial spondyloarthritis: focus on differential diagnosis in women

OBJECTIVE

To review the role of sacro-iliac magnetic resonance imaging (MRI) in the diagnosis of axial spondyloarthritis (AxSpA), with a focus on gender differences.

METHODS

The experience of the authors and the results of an informal literature review are reported.

RESULTS

Inflammatory changes of the sacro-iliac joint are the hallmark of AxSpA. Early, non-radiographic sacroiliitis may be diagnosed with MRI through the assessment of bone marrow edema (BMO) as well as concomitant structural damage. The MRI protocol should include three necessary sequences, i.e., fat-saturated T2-weighted sequences on two orthogonal planes, T1-weighted semi-coronal sequence, and fat-suppressed T1-weighted semi-coronal sequence. Inflammatory changes comprise required signs (BMO and/or osteitis) and additional signs, including synovitis (better defined as joint space enhancement), enthesitis, and capsulitis. Structural changes consist of erosions, sclerosis, fat metaplasia, and ankylosis. Due to mechanical axial strain, inflammatory changes in the sacro-iliac joint can be found in healthy individuals, runners, and patients with nonspecific low back pain. The prevalence of BMO is higher in women during pregnancy and postpartum, even 12 months after childbirth, but the extent and distribution of MRI findings may help in the differential diagnosis. Other challenges in the MRI diagnosis of sacroiliitis are subchondral T2 hyperintensity during developmental age, periarticular sclerosis in healthy subjects, or osteitis condensans ilii, and several pathological conditions that may mimic AxSpA, some of which are more frequently found in women.

CONCLUSIONS

The described diagnostic challenges impose a multidisciplinary approach combining imaging findings with clinical and laboratory data.

Comparison of established and preliminarily proposed ASAS MRI working group cut-offs for inflammatory MRI lesions in the sacroiliac joints in radiographic and non-radiographic axial spondyloarthritis

BACKGROUND

A consensus definition for active sacroiliitis by MRI, mentioned in the Assessment of SpondyloArthritis International Society (ASAS) classification criteria for axial spondyloarthritis (axSpA), was published in 2009 and included a qualitative and quantitative MRI cut-off component. In 2021, updates to the quantitative component were preliminarily proposed. This post hoc analysis of part A of the phase 3 open-label C-OPTIMISE study (NCT02505542) explores the differences by applying the 2009 and preliminary 2021 inflammatory cut-offs on clinical outcomes of axSpA patients treated with certolizumab pegol.

METHODS

Baseline MRI scans were used to classify 657 patients as MRI+ or MRI- according to the quantitative components of the 2009 and preliminary 2021 MRI cut-offs for inflammatory lesions. Clinical outcomes, including ASAS ≥40% improvement (ASAS40), Ankylosing Spondylitis Disease Activity Score and Bath Ankylosing Spondylitis Disease Activity Index, were reported to week 48.

RESULTS

Across all analysed outcomes, 2009 MRI+ and preliminary 2021 MRI+ subgroups showed similar results. Notably, clinical outcomes for the discordant group (2009 MRI+but preliminary 2021 MRI- group; 53/657 [8.1%]) were close to those seen in MRI- patients according to either 2009 or preliminary 2021 inflammatory cut-offs, and notably different from the totality of MRI+ subgroups.

CONCLUSION

This analysis suggests that the preliminary 2021 cut-offs for MRI inflammatory lesions may slightly increase the specificity of the quantitative part of the 2009 MRI inflammatory lesion definition. The effects of the updated MRI cut-offs need to be assessed on the basis of efficacy outcomes and with the inclusion of aspects of structural changes.

TRIAL REGISTRATION NUMBER

NCT02505542.

Magnetic Resonance Imaging Topography of Bone Marrow Edema in the Sacroiliac Joint of Postpartum Women

OBJECTIVE

A traditional monoplanar semicoronal and a biplanar magnetic resonance imaging (MRI) assessment method were used to compare the topographical distribution of postpartum strain-related bone marrow edema (BME) at the sacroiliac joint (SIJ).

METHODS

The presence and topographical location of SIJ BME were assessed independently by three readers in 71 women 12 months postpartum. A traditional monoplanar semicoronal and a biplanar BME evaluation by 8 (upper and lower) and 12 joint (upper, middle, and lower) regions, respectively, was performed with >4 weeks between the two assessments. Descriptive results were reported as mean ± SD and ranges, and interreader agreement by intraclass correlation coefficient (ICC).

RESULTS

By semicoronal assessment, 38 (53.5%) women had BME with a mean ± SD SPARCC score of 2.3 ± 4.0 (range 0-22; ICC 0.93, 95% confidence interval [CI] 0.92-0.94). Forty-one (57.8%) had BME by biplanar assessment with a mean ± SD sum score of 2.9 ± 5.8 (range 0-32.7; ICC 0.89, 95% CI 0.88-0.91). By semicoronal assessment, the highest frequency and mean SPARCC scores were in the anterior upper regions of ilium (24%, mean 0.6) and sacrum (21%, mean 0.3) followed by the posterior upper sacral (20%, mean 0.4) and posterior lower iliac (20%, mean 0.3) regions. By biplanar assessment, the anterior middle joint regions had highest BME frequency and sum scores, sacral side (32%, mean 1.9) and iliac side (27%, mean 2.0), respectively; frequencies and sum scores were generally higher in the anterior compared to the posterior joint regions.

CONCLUSION

The 12-region biplanar assessment revealed a predominantly anterior middle location of postpartum SIJ BME whereas the 8-region monoplanar approach did not demarcate distinct strain-prone SIJ regions. Complementing traditional monoplanar semicoronal SIJ MRI evaluation by a semiaxial assessment may facilitate discrimination of strain-related conditions from early axial spondyloarthritis.

Imaging of Sacroiliac Pain: The Current State-of-the-Art

Pain in the sacroiliac (SI) region is a common clinical manifestation, often caused by diseases involving the SI joints. This is typically due to inflammation or degenerative changes, while infections or cancer are less frequent causes. The SI joint is challenging to image accurately because of its distinct anatomical characteristics. For an accurate diagnosis, conventional radiography often needs to be supplemented with more precise methods such as magnetic resonance imaging (MRI) or computed tomography (CT). Sacroiliitis, a common presenting feature of axial spondyloarthritis (axial SpA), manifests as bone marrow edema, erosions, sclerosis, and joint space narrowing. Septic sacroiliitis and repetitive stress injuries in sports can also cause changes resembling inflammatory sacroiliitis. Other conditions, such as osteitis condensans ilii (OCI), can mimic the radiologic characteristics of sacroiliitis. Inflammatory lesions are diagnosed by concurrent erosions, hyperostosis, and ankylosis. Ligament ossifications or mechanical stress can also result in arthritic disorders. Determining the exact diagnosis can be aided by the distribution of the lesions. Inflammatory lesions can affect any part of the articulation, including the inferior and posterior portions. Mechanical lesions, such as those seen in OCI, often occur in the anterior middle region of the joint. In cases of idiopathic skeletal hyperostosis, ligament ossification is found at the joint borders. This pictorial essay describes common SI joint problems, illustrated with multimodal imaging data. We, also, discuss strategies for selecting the best imaging modalities, along with imaging pitfalls, key points, and approaches for treating patients with suspected inflammatory back pain.

Diagnosis, monitoring, and management of axial spondyloarthritis

Axial spondyloarthritis (axSpA) is a chronic condition predominantly affecting the spine and sacroiliac joints. This article provides an in-depth overview of the current approaches to diagnosing, monitoring, and managing axSpA, including insights into developing terminology and diagnostic difficulties. A substantial portion of the debate focuses on the challenging diagnostic procedure, noting the difficulty of detecting axSpA early, particularly before the appearance of radiologic structural changes. Despite normal laboratory parameters, more than half of axSpA patients experience symptoms. X-ray and magnetic resonance imaging (MRI) are essential for evaluating structural damage and inflammation. MRI can be beneficial when there is no visible structural damage on X-ray as it can help unravel bone marrow edema (BME) as a sign of ongoing inflammation. The management covers both non-pharmacological and pharmacological approaches. Lifestyle modifications, physical activity, and patient education are essential components of the management. Pharmacological therapy, including nonsteroidal anti-inflammatory drugs (NSAIDs) and biologic disease-modifying anti-rheumatic drugs (bDMARDs), are explored, emphasizing individualized treatment. To effectively manage axSpA, a comprehensive and well-coordinated approach is necessary, emphasizing the significance of a multidisciplinary team. Telehealth applications play a growing role in axSpA management, notably in reducing diagnostic delays and facilitating remote monitoring. In conclusion, this article underlines diagnostic complexities and emphasizes the changing strategy of axSpA treatment. The nuanced understanding offered here is designed to guide clinicians, researchers, and healthcare providers toward a more comprehensive approach to axSpA diagnosis and care.

Assessment of enthesopathy in conventional pelvis radiography: Another tool for spondyloarthritis diagnosis beyond sacroiliitis

INTRODUCTION/OBJECTIVES

Enthesitis is a cardinal feature of spondylarthritis (SpA), and the pelvis is a common site of enthesitis. This study aimed to establish the association between pelvic enthesis involvement on pelvic X-ray and SpA diagnosis through a radiographic enthesis index (REI) and to assess the reliability and accuracy of this REI.

MATERIALS AND METHODS

The participants were SpA patients and a control group composed of patients with chronic lumbar pain without SpA. Three blinded observers assessed each pelvic radiography three times. Three zones were used: Zone I (ZI), the iliopubic ramus; Zone II (ZII), the pubic symphysis, and Zone III (ZIII), the ischiopubic ramus. A grading system was created from 0 to 3 [Grade 0, normal; Grade 1, minimal changes (subcortical bone demineralization and/or periosteal wishkering, seen as radiolucency and trabeculation of the cortical bone upon tendon insertion); Grade 2, destructive changes (Grade 1 findings and erosions at the enthesis site); and Grade 3, findings of Grade 2 plus >2 mm whiskering out of the cortical bone) for the REI. The sum of the results of the three zones was called the total REI. For statistical analysis, we used the weighted kappa statistic adjusted for prevalence and bias using Gwet's agreement coefficient.

RESULTS

We enrolled 161 patients, 111 of them with SpA (39.6 % with axial SpA and 47.7 % with peripheral SpA) and 50 without SpA. In the SpA group, 36.7 % and 25.7 % had REI Grades 2 and 3 in ZIII, respectively, while only 6 % of the controls had these grades. For ZI, the frequency of Grades 1 to 3 was 42.3 % in the SpA group (8.1 %, 14.4 %, and 19.8 %, respectively), compared to only 2 % in the controls. ZII was unaffected in most of the patients with SpA (82.9 %) and in the controls (98 %). In the control group, Grade 0 was the most common REI grade in all three zones. The agreement was almost perfect for each zone and between the independent readers. The ROC-curve analysis showed that the highest performance areas were the total REI, ZIII, and ZI. Most (75 %) of the SpA patients without sacroiliitis on X-ray were REI-positive. The sensitivity of the REI for SpA diagnosis was 82 %, while the sensitivity of sacroiliitis on X-ray was 38.7 %.

CONCLUSIONS

The assessment of pelvic enthesis using the REI on pelvic radiography may be useful for SpA diagnosis. Total REI, ZIII, and ZI had the highest accuracy and almost perfect reliability. The REI is especially helpful in patients without sacroiliitis on imaging.

Artificial intelligence and machine learning in axial spondyloarthritis

PURPOSE OF REVIEW

To evaluate the current applications and prospects of artificial intelligence and machine learning in diagnosing and managing axial spondyloarthritis (axSpA), focusing on their role in medical imaging, predictive modelling, and patient monitoring.

RECENT FINDINGS

Artificial intelligence, particularly deep learning, is showing promise in diagnosing axSpA assisting with X-ray, computed tomography (CT) and MRI analyses, with some models matching or outperforming radiologists in detecting sacroiliitis and markers. Moreover, it is increasingly being used in predictive modelling of disease progression and personalized treatment, and could aid risk assessment, treatment response and clinical subtype identification. Variable study designs, sample sizes and the predominance of retrospective, single-centre studies still limit the generalizability of results.

SUMMARY

Artificial intelligence technologies have significant potential to advance the diagnosis and treatment of axSpA, providing more accurate, efficient and personalized healthcare solutions. However, their integration into clinical practice requires rigorous validation, ethical and legal considerations, and comprehensive training for healthcare professionals. Future advances in artificial intelligence could complement clinical expertise and improve patient care through improved diagnostic accuracy and tailored therapeutic strategies, but the challenge remains to ensure that these technologies are validated in prospective multicentre trials and ethically integrated into patient care.

Axial Spondyloarthritis: Does Magnetic Resonance Imaging Classification Improve Report Interpretation

OBJECTIVE

The interpretation of magnetic resonance imaging (MRI) reports is crucial for the diagnosis of axial spondyloarthritis, but the subjective nature of narrative reports can lead to varying interpretations. This study presents a validation of a novel MRI reporting system for the sacroiliac joint in clinical practice.

METHODS

A historical review was conducted on 130 consecutive patients referred by 2 rheumatologists for initial MRI assessment of possible axial spondyloarthritis. The original MRI reports were interpreted by the rheumatologists and the radiologist who originally read the images and then categorized according to the novel system. Two musculoskeletal radiologists then reinterpreted the original MRI scans using the new system, and the resulting reports were interpreted and categorized by the same rheumatologists. The quality of the new framework was assessed by comparing the interpretations of both reports.

RESULTS

Ninety-two patients met the study criteria. The rheumatologists disagreed on the categorization of the original MRI reports in 12% of cases. The rheumatologists and original radiologists disagreed on the categorization of the initial report in 23.4% of cases. In contrast, there was 100% agreement between the rheumatologists and radiologists on the categorization of the new MRI report.

CONCLUSION

The new MRI categorization system significantly improved the agreement between the clinician and radiologist in report interpretation. The system provided a standard vocabulary for reporting, reduced variability in report interpretation, and may therefore improve clinical decision-making.

The value of a repeat MRI examination of the sacroiliac joints following an inconclusive initial examination

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.

Exploring complement biomarkers in suspected axial spondyloarthritis

OBJECTIVES

To investigate lectin pathway proteins (LPPs) as biomarkers for axial spondyloarthritis (axSpA) in a cross-sectional cohort with a suspicion of axSpA, comprising newly diagnosed axSpA and chronic low back pain (cLBP) individuals.

METHODS

Serum samples from 515 participants within the OptiRef cohort, including 151 axSpA patients and 364 cLBP patients, were measured using immunoassays for LPPs (mannan-binding lectin (MBL), collectin liver-1 (CL-L1), M-ficolin, H-ficolin and L-ficolin, MBL-associated serine proteases (MASP)-1, -2 and -3, MBL-associated proteins (MAp19 and MAp44) and the complement activation product C3dg).

RESULTS

Serum levels of L-ficolin, MASP-2 and C3dg were elevated in axSpA patients, whereas levels of MASP-3 and CL-L1 were decreased, and this remained significant for C3dg and MASP-3 after adjustment for C reactive protein (CRP). A univariate regression analysis showed serum levels of CL-L1, MASP-2, MASP-3 and C3dg to predict the diagnosis of axSpA, and MASP-3 and C3dg remained significant in a multivariate logistic regression analysis. Assessment of the diagnostic potential showed that a combination of human leukocyte antigen B27 (HLA-B27) and measurements of L-ficolin, MASP-3 and C3dg increased the diagnostic specificity for axSpA, however, with a concomitant loss of sensitivity.

CONCLUSIONS

Serum levels of complement activation, that is, C3dg, and MASP-3 differed significantly between axSpA and cLBP patients after adjustment for CRP. Although combining HLA-B27 with measurements of L-ficolin, MASP-3 and C3dg increased the diagnostic specificity for axSpA, this seems unjustified due to the concomitant loss of sensitivity. However, both C3dg and MASP-3 were associated with axSpA diagnosis in multivariate logistic regression, suggesting an involvement of complement in the inflammatory processes and possibly pathogenesis in axSpA.

Whole-body MRI for the investigation of joint involvement in inflammatory arthritis

OBJECTIVES

This study aimed to develop a novel whole-body MRI protocol capable of assessing inflammatory arthritis at an early stage in multiple joints in one examination.

MATERIALS AND METHODS

Forty-six patients with inflammatory joint symptoms and 9 healthy volunteers underwent whole-body MR imaging on a 3.0 T MRI scanner in this prospective study. Image quality and pathology in each joint, bursae, entheses and tendons were scored by two of three radiologists and compared to clinical joint scores. Participants were divided into three groups based on diagnosis at 1-year follow-up (healthy volunteers, rheumatoid arthritis and all other types of arthritis). Radiology scores were compared between the three groups using a Kruskal-Wallis test. The clinical utility of radiology scoring was compared to clinical scoring using ROC analysis.

RESULTS

A protocol capable of whole-body MR imaging of the joints with an image acquisition time under 20 min was developed with excellent image quality. Synovitis scores were significantly higher in patients who were diagnosed with rheumatoid arthritis at 12 months (p < 0.05). Radiology scoring of bursitis showed statistically significant differences between each of the three groups-healthy control, rheumatoid arthritis and non-rheumatoid arthritis (p < 0.05). There was no statistically significant difference in ROC analysis between MRI and clinical scores.

CONCLUSION

This study has developed a whole-body MRI joint imaging protocol that is clinically feasible and shows good differentiation of joint pathology between healthy controls, patients with rheumatoid arthritis and patients with other forms of arthritis.

An Unusual Mimic of Axial Spondyloarthritis: A Case Report

Axial spondyloarthritis (SpA) is a chronic inflammatory condition predominantly affecting the sacroiliac joints and spine, typically presenting before the age of 45 years with inflammatory back pain. However, diagnostic challenges arise when atypical features and negative autoimmune markers obscure the clinical picture. We present a case of a male in his 40s with no significant medical history, presenting with a three-month history of inflammatory back pain. Despite negative human leukocyte antigen B27 (HLA-B27) status, clinical examination, including positive findings on the FABER (flexion, abduction, and external rotation) test and exaggerated muscle tenderness, raised suspicion of axial SpA. An MRI of the pelvis confirmed bilateral symmetrical sacroiliitis, supporting the diagnosis. Unexpectedly, further investigations revealed a very low vitamin D level, normal calcium levels, and elevated parathyroid hormone (PTH), suggesting secondary hyperparathyroidism. A subsequent PET scan disclosed increased uptake posterior to the right lobe of the thyroid, prompting consideration of secondary hyperparathyroidism due to severe vitamin D deficiency. Treatment with vitamin D supplementation and nonsteroidal anti-inflammatory drugs yielded remarkable improvement in symptoms, with normal repeat blood investigations post-treatment. This case underscores the importance of a comprehensive diagnostic approach in patients with inflammatory back pain, especially when classical markers such as HLA-B27 are negative. It highlights the potential interplay between axial SpA and secondary hyperparathyroidism, emphasizing the need for vigilance and interdisciplinary collaboration in clinical practice.

Can rheumatologists unequivocally diagnose axial spondyloarthritis in patients with chronic back pain of less than 2 years duration? Primary outcome of the 2-year SPondyloArthritis Caught Early (SPACE) cohort

OBJECTIVES

To investigate the prevalence of axial spondyloarthritis (axSpA) in patients with chronic back pain (CBP) of less than 2 years (2y) duration referred to the rheumatologist, the development of diagnosis over time, and patient characteristics of those developing definite (d-)axSpA over 2y.

METHODS

We analysed the 2y data from SPondyloArthritis Caught Early, a European cohort of patients (<45 years) with CBP (≥3 months, ≤2y) of unknown origin. The diagnostic workup comprised evaluation of clinical SpA features, acute phase reactants, HLA-B27, radiographs and MRI (sacroiliac joints and spine), with repeated assessments. At each visit (baseline, 3 months, 1y and 2y), rheumatologists reported a diagnosis of axSpA or non-axSpA with level of confidence (LoC; 0-not confident at all to 10-very confident).

MAIN OUTCOME

axSpA diagnosis with LoC≥7 (d-axSpA) at 2y.

RESULTS

In 552 patients with CBP, d-axSpA was diagnosed in 175 (32%) at baseline and 165 (30%) at 2y. Baseline diagnosis remained rather stable: at 2y, baseline d-axSpA was revised in 5% of patients, while 8% 'gained' d-axSpA. Diagnostic uncertainty persisted in 30%. HLA-B27+ and baseline sacroiliitis imaging discriminated best 2y-d-axSpA versus 2y-d-non-axSpA patients. Good response to non-steroidal anti-inflammatory drugs and MRI-sacroiliitis most frequently developed over follow-up in patients with a new d-axSpA diagnosis. Of the patients who developed MRI-sacroiliitis, 7/8 were HLA-B27+ and 5/8 male.

CONCLUSION

A diagnosis of d-axSpA can be reliably made in nearly one-third of patients with CBP referred to the rheumatologist, but diagnostic uncertainty may persist in 5%-30% after 2y. Repeated assessments yield is modest, but repeating MRI may be worthwhile in male HLA-B27+ patients.

Diagnostic accuracy in axial spondyloarthritis: a systematic evaluation of the role of clinical information in the interpretation of sacroiliac joint imaging

OBJECTIVES

Radiography and MRI of the sacroiliac joints (SIJ) are relevant for the diagnosis and classification of patients with axial spondyloarthritis (axSpA). This study aimed to evaluate the impact of clinical information (CI) on the accuracy of imaging interpretation.

METHODS

Out of 109 patients referred because of suspicion of axSpA with complete imaging sets (radiographs and MRI of SIJ), 61 were diagnosed with axSpA (56%). Images were independently evaluated by three radiologists in four consecutive reading campaigns: radiographs and radiographs+MRI without and with CI including demographic data, SpA features, physical activity and pregnancy. Radiographs were scored according to the modified New York criteria, and MRIs for inflammatory and structural changes compatible with axSpA (yes/no). The clinical diagnosis was taken as reference standard. The compatibility of imaging findings with a diagnosis of axSpA (precision) before and after the provision of CI and radiologists' confidence with their findings (0-10) were evaluated.

RESULTS

The precision of radiographs evaluation without versus with CI increased from 70% to 78% (p=0.008), and for radiographs+MRI from 81% to 82% (p=1.0), respectively. For CR alone, the sensitivity and specificity of radiologic findings were 51% and 94% without and 60% and 100% with CI, while, for radiographs+MRI, they were 74% and 90% vs 71% and 98%, respectively. The diagnostic confidence of radiologists increased from 5.2±1.9 to 6.0±1.7 with CI for radiographs, and from 6.7±1.6 to 7.2±1.6 for radiographs+MRI, respectively.

CONCLUSION

The precision, specificity and diagnostic confidence of radiologic evaluation increased when CI was provided.

[Diagnosis and classification of axial spondyloarthritis (axSpA) - the current status]

Axial spondyloarthritis (axSpA) is an inflammatory rheumatic disease typically characterized by inflammatory back pain (IBP). The term axSpA has largely replaced the long-used term ankylosing spondylitis (AS). IBP is caused by inflammation in the axial skeleton, with the sacroiliac joints (SIJ) being particularly frequently affected initially. The spine is usually added in later stages, which is then increasingly characterized structurally by the formation of new bone. The overall concept of spondyloarthritis includes other disease manifestations such as uveitis, psoriasis and colitis and comorbidities such as cardiovascular disease and osteoporosis.The ASAS classification criteria for axSpA, in place since 2009, have replaced the 1984 modified New York criteria. In the former, in addition to conventional X-rays, changes in the SIJ detected by magnetic resonance imaging (MRI) and also the detection of HLA B27 have, for the first time, played a role. It is important to note that these are not diagnostic criteria, as they do not exist. This paper outlines 10 points that should be considered when making a diagnosis.

The sacroiliac joint across ages - what is normal?

The anatomy of the sacroiliac joint (SIJ) is complex with wide variations inter-individually as well as intra-individually (right versus left) and a frequent occurrence of anatomical variants. Besides, the joints are subject to strain, which may elicit non-inflammatory subchondral changes such as bone marrow edema (BME), sclerosis, and fat deposition simulating inflammatory SIJ changes. Furthermore, normal physiological changes during skeletal maturation can make interpretation of SIJ magnetic resonance imaging in children challenging. Knowledge about the wide range of normal findings is therefore important to avoid misinterpretation of findings as pathological. This review describes the current knowledge about normal SIJ findings across all ages.

Use of MRI-based deep learning radiomics to diagnose sacroiliitis related to axial spondyloarthritis

OBJECTIVES

This study aimed to evaluate the performance of a deep learning radiomics (DLR) model, which integrates multimodal MRI features and clinical information, in diagnosing sacroiliitis related to axial spondyloarthritis (axSpA).

MATERIAL & METHODS

A total of 485 patients diagnosed with sacroiliitis related to axSpA (n = 288) or non-sacroiliitis (n = 197) by sacroiliac joint (SIJ) MRI between May 2018 and October 2022 were retrospectively included in this study. The patients were randomly divided into training (n = 388) and testing (n = 97) cohorts. Data were collected using three MRI scanners. We applied a convolutional neural network (CNN) called 3D U-Net for automated SIJ segmentation. Additionally, three CNNs (ResNet50, ResNet101, and DenseNet121) were used to diagnose axSpA-related sacroiliitis using a single modality. The prediction results of all the CNN models across different modalities were integrated using a stacking method based on different algorithms to construct ensemble models, and the optimal ensemble model was used as DLR signature. A combined model incorporating DLR signature with clinical factors was developed using multivariable logistic regression. The performance of the models was evaluated using receiver operating characteristic (ROC) curves, calibration curves, and decision curve analysis (DCA).

RESULTS

Automated deep learning-based segmentation and manual delineation showed good correlation. ResNet50, as the optimal basic model, achieved an area under the curve (AUC) and accuracy of 0.839 and 0.804, respectively. The combined model yielded the highest performance in diagnosing axSpA-related sacroiliitis (AUC: 0.910; accuracy: 0.856) and outperformed the best ensemble model (AUC: 0.868; accuracy: 0.825) (all P < 0.05). Moreover, the DCA showed good clinical utility in the combined model.

CONCLUSION

We developed a diagnostic model for axSpA-related sacroiliitis by combining the DLR signature with clinical factors, which resulted in excellent diagnostic performance.

Knowledge Mapping Analysis of Research on Pregnancy-Related Pelvic Girdle Pain (PPGP) from 2002 to 2022 Using Bibliometrics

Background

Pregnancy-related Pelvic Girdle Pain (PPGP) is a prevalent condition characterized by various physiological and pathological processes in the female body. The objective of this study is to offer a comprehensive understanding of the current research landscape, key areas of interest, and potential future directions in the field of PPGP.

Methods

Using Web of Science, we explored PPGP literature from 2002 to 2022. VOSviewer and CiteSpace facilitated a quantitative analysis, revealing co-authorship patterns, co-occurring themes, citations, and co-citations.

Results

We identified, peaking at 99 publications in 2021. The United States led with 138 publications and the highest citation count (3160). The Karolinska Institute boasted the highest tally of publications (n = 21). Regarding the volume of publications, the esteemed journal of BMC Pregnancy and Childbirth attained the foremost position. Notably, Gutke, Annelie emerged as the most prolific and highly cited author. The analysis of keyword co-occurrence and co-citation clustering unveiled an intricate tapestry of PPGP studies, spanning various domains including risk factors, mechanistic intricacies, diagnostic benchmark, treatment modalities, and far-reaching ramifications on one's quality of life.

Conclusion

Research endeavors exploring PPGP have unveiled an enduring trajectory of growth in contemporary times. The existing body of research primarily focuses on delving into the intricate interplay of epidemiological factors and the profound implications of interventions encompassing physical therapy, exercise protocols, and diverse modes of pain management within the domain of PPGP. Multidisciplinary integration encapsulates a prevailing trajectory of progress within this domain, while the focal point of future inquiries into PPGP may revolve around subjects pertaining to standardized outcome reporting.

A New Approach to the Treatment of Sacroiliac Joint Pain and First Patient-Reported Outcomes Using a Novel Arthrodesis Technique for Sacroiliac Joint Fusion

Purpose

To report the development of a new sacroiliac joint (SIJ) arthrodesis system that can be used for isolated fusion of the SIJ and, unlike known implant systems, in combination with lumbar instrumentation or as an alternative to existing sacropelvic fixation (SPF) methods, and the patient-reported outcomes in two cases.

Materials and Methods

After a comprehensive review of 207 pelvic computed tomography (CT) datasets, an implant body was designed. Its shape was modeled based on the SIJ recess. A screw anchored in the ilium secures the position of the implant and allows connection to lumbar instrumentation. Two patients with confirmed SIJ syndrome underwent surgery with the anatomically adapted implant. They were evaluated preoperatively, 6 months, and 12 months postoperatively. Visual Analogue Scale (VAS), Oswestry Disability Index (ODI), Million Visual Analogue Scale (MVAS), Roland Morris Score (RMS), reduction of SIJ/leg pain, and work status were assessed. Bony fusion of the SIJ was evaluated by radiographs and CT 12 months after the procedure.

Results

Analysis of pelvic CT data revealed a wedge-shaped implant body in four different sizes. In the two patients, VAS decreased from 88 to 33 points, ODI improved from 67 to 35%, MVAS decreased from 80 to 36%, and RMS decreased from 18 to 9 points 12 months after surgery. SIJ pain reduction was 80% and 90%, respectively. Follow-up CT and radiographs showed solid bony integration.

Conclusion

The implant used takes into account the unique anatomy of the SIJ and also meets the requirements of a true arthrodesis. Initial results in two patients are promising. Biomechanical and clinical studies will have to show whether the considerable theoretical advantages of the new implant system over existing SIJ implants - in particular the possibility of connection to a lumbar stabilization system - and SPFs can be put into practice.

Performance of clinical, laboratory and imaging features for diagnosing spondyloarthritis-a systematic literature review and meta-analysis

OBJECTIVE

The Berlin algorithm was developed to help diagnosing axial spondyloarthritis (axSpA), but new studies suggest some features typical of SpA are less specific than previously assumed. Furthermore, evidence is lacking for other SpA subtypes (e.g. peripheral SpA). We aimed to review the evidence on the performance of SpA features for diagnosing each SpA subtype.

METHODS

Systematic literature review of studies reporting the diagnostic performance of ≥ 1 SpA feature in patients with suspected SpA. The external reference was the rheumatologist's diagnosis of SpA. Meta-analysis was performed, separately for each SpA subtype, to estimate pooled sensitivity, specificity, positive (LR+) and negative (LR-) likelihood ratios. Meta-regression assessed the effect of covariates (e.g. feature's prevalence) on each feature's performance.

RESULTS

Of 13 844 articles screened, 46 were included. Sacroiliitis on magnetic resonance imaging, damage on pelvic radiographs and elevated C-reactive protein (CRP) had the best balance between LR+ and LR- (LR + 3.9-17.0, LR- 0.5-0.7) for diagnosing axSpA. HLA-B27 had an LR+ lower than anticipated (LR + =3.1). Inflammatory back pain (IBP) had low LR + (LR+∼1), but substantially decreased the likelihood of axSpA when absent (LR-=0.3). Conversely, peripheral features and extra-musculoskeletal manifestations showed high LR + (LR+ 1.6-5.0), but were as common in axSpA as no-axSpA (LR-∼1). The specificity of most features was reduced in settings when these were highly prevalent. Limited data precluded a detailed analysis on diagnosing other SpA subtypes.

CONCLUSION

Imaging features and CRP have good diagnostic value for axSpA. However, the specificity of other features, especially HLA-B27 and IBP, is lower than previously known.

The Role of Early Treatment in the Management of Axial Spondyloarthritis: Challenges and Opportunities

Axial spondyloarthritis (axSpA) is a chronic, inflammatory rheumatic disease that primarily affects the axial skeleton, often inflicting severe pain, diminished mobility, and a compromised quality of life. The advent of Assessment of SpondyloArthritis international Society (ASAS) classification criteria for spondyloarthritis (SpA) have enabled the classification of patients with axSpA in the non-radiographic stage but poorly perform if mistakenly used for diagnostic purposes. Despite notable progress in early diagnosis facilitated by referral strategies and extensive magnetic resonance imaging (MRI) utilization, diagnostic delays persist as a concerning issue. This underscores the urgency to narrow the diagnostic gap and highlights the critical role of early diagnosis in mitigating the long-term structural damage associated with this condition. Research into the impact of non-steroidal anti-inflammatory drugs (NSAIDs) and biologic disease-modifying antirheumatic drugs (bDMARDs) on inflammatory symptoms and radiographic progression has been extensive. A compelling body of evidence suggests that early intervention leads to superior disease outcomes. However, most of these studies have centered on patients with established diseases rather than those in the early stages. Consequently, findings from studies on early pharmacological intervention remain inconclusive, and the potential for modifying the disease trajectory is still debatable. Without precise data from clinical trials, insights from basic science regarding the pathogenic mechanisms might point toward potential targets that warrant early intervention in the disease process. This review underscores the urgency of early diagnosis and intervention in axSpA, highlighting ongoing research gaps and the need for further exploration to improve patient outcomes.

Research on automatic recognition radiomics algorithm for early sacroiliac arthritis based on sacroiliac MRI imaging

OBJECTIVE

To create an automated machine learning model using sacroiliac joint MRI imaging for early sacroiliac arthritis detection, aiming to enhance diagnostic accuracy.

METHODS

We conducted a retrospective analysis involving 71 patients with early sacroiliac arthritis and 85 patients with normal sacroiliac joint MRI scans. Transverse T1WI and T2WI sequences were collected and subjected to radiomics analysis by two physicians. Patients were randomly divided into training and test groups at a 7:3 ratio. Initially, we extracted the region of interest on the sacroiliac joint surface using ITK-SNAP 3.6.0 software and extracted radiomic features. We retained features with an Intraclass Correlation Coefficient > 0.80, followed by filtering using max-relevance and min-redundancy (mRMR) and LASSO algorithms to establish an automatic identification model for sacroiliac joint surface injury. Receiver operating characteristic (ROC) curves were plotted, and the area under the ROC curve (AUC) was calculated. Model performance was assessed by accuracy, sensitivity, and specificity.

RESULTS

We evaluated model performance, achieving an AUC of 0.943 for the SVM-T1WI training group, with accuracy, sensitivity, and specificity values of 0.878, 0.836, and 0.943, respectively. The SVM-T1WI test group exhibited an AUC of 0.875, with corresponding accuracy, sensitivity, and specificity values of 0.909, 0.929, and 0.875, respectively. For the SVM-T2WI training group, the AUC was 0.975, with accuracy, sensitivity, and specificity values of 0.933, 0.889, and 0.750. The SVM-T2WI test group produced an AUC of 0.902, with accuracy, sensitivity, and specificity values of 0.864, 0.889, and 0.800. In the SVM-bimodal training group, we achieved an AUC of 0.974, with accuracy, sensitivity, and specificity values of 0.921, 0.889, and 0.971, respectively. The SVM-bimodal test group exhibited an AUC of 0.964, with accuracy, sensitivity, and specificity values of 0.955, 1.000, and 0.875, respectively.

CONCLUSION

The radiomics-based detection model demonstrates excellent automatic identification performance for early sacroiliitis.

Sacroiliac joint MRI for diagnosis of ax-SpA: algorithm to improve the specificity of the current ASAS MRI criteria

OBJECTIVE

To compare sacroiliac joint (SIJ) lesions on MRI in women with versus without axial spondyloarthritis (ax-SpA) and establish an algorithm to determine whether such lesions are due to ax-SpA.

METHODS

This retrospective comparative study assessed bone marrow edema (BME), sclerosis, erosions, osteophytes, and ankylosis at the SIJ in two groups of women, one with and another without ax-SpA. Sensitivity and specificity were calculated for combinations/characteristics of lesions, using rheumatologists' assessment with assessment of spondyloarthritis international society (ASAS) criteria as the gold standard for diagnosis of ax-SpA.

RESULTS

Compared to women without ax-SpA, women with ax-SpA had more BME (61% vs 17%, p < 0.001), sclerosis (40% vs 22%, p < 0.001), erosions (35% vs 5%, p < 0.001), and ankylosis (2% vs 0%, p = 0.007), but less osteophytes (5% vs 33%, p < 0.001). The ASAS MRI criteria yielded 59% sensitivity and 88% specificity, while a new algorithm achieved 56% sensitivity and 95% specificity using the following criteria: no osteophytes at the SIJ and either (i) BME at the SIJ with at least one dimension ≥ 8 mm or (ii) at least one erosion at the SIJ.

CONCLUSIONS

We recommend the following pragmatic algorithm for MRI diagnosis of ax-SpA in women: no osteophytes at the SIJ and either (i) BME at the SIJ with at least one dimension ≥ 8 mm or (ii) at least one erosion at the SIJ. The false positive rate when using the new algorithm (3.3%) is less than half than when using the ASAS MRI criteria (7.7%); thus, its application in clinical practice could reduce overdiagnosis and prevent overtreatment of ax-SpA.

CLINICAL RELEVANCE STATEMENT

The developed algorithm has a false-positive rate that is less than half than when using the ASAS MRI criteria (3.3% vs 7.7%), thus its application in clinical practice could reduce overdiagnosis and prevent overtreatment of axial spondyloarthritis.

KEY POINTS

• Compared to women without axial spondyloarthritis (ax-SpA), women with ax-SpA had a significantly higher prevalence of bone marrow edema (BME), sclerosis, erosions, and ankylosis, but a significantly lower prevalence of osteophytes. • A new algorithm for positive ax-SpA based on sacroiliac joint MRI was developed: no osteophytes at the sacroiliac joint (SIJ) and either (i) BME at the SIJ with at least one dimension ≥ 8 mm or (ii) at least one erosion at the SIJ. • We recommend this new algorithm for diagnosis of ax-SpA in women, as it has a significantly better specificity than the assessment of spondyloarthritis international society (ASAS) MRI criteria and less than half the false positive rate; thus, its application in clinical practice could reduce overdiagnosis and prevent overtreatment of ax-SpA.

Machine Learning Pipeline for Predicting Bone Marrow Edema Along the Sacroiliac Joints on Magnetic Resonance Imaging

OBJECTIVE

We aimed to develop and validate a fully automated machine learning (ML) algorithm that predicts bone marrow edema (BME) on a quadrant level in sacroiliac (SI) joint magnetic resonance imaging (MRI).

METHODS

A computer vision workflow automatically locates the SI joints, segments regions of interest (ilium and sacrum), performs objective quadrant extraction, and predicts presence of BME, suggestive of inflammatory lesions, on a quadrant level in semicoronal slices of T1/T2-weighted MRI scans. Ground truth was determined by consensus among human readers. The inflammation classifier was trained using a ResNet18 backbone and five-fold cross-validated on scans of patients with spondyloarthritis (SpA) (n = 279), postpartum individuals (n = 71), and healthy subjects (n = 114). Independent SpA patient MRI scans (n = 243) served as test data set. Patient-level predictions were derived from aggregating quadrant-level predictions, ie, at least one positive quadrant.

RESULTS

The algorithm automatically detects the SI joints with a precision of 98.4% and segments ilium/sacrum with an intersection over union of 85.6% and 67.9%, respectively. The inflammation classifier performed well in cross-validation: area under the curve (AUC) 94.5%, balanced accuracy (B-ACC) 80.5%, and F1 score 64.1%. In the test data set, AUC was 88.2%, B-ACC 72.1%, and F1 score 50.8%. On a patient level, the model achieved a B-ACC of 81.6% and 81.4% in the cross-validation and test data set, respectively.

CONCLUSION

We propose a fully automated ML pipeline that enables objective and standardized evaluation of BME along the SI joints on MRI. This method has the potential to screen large numbers of patients with (suspected) SpA and is a step closer towards artificial intelligence-assisted diagnosis and follow-up.

Assessment of axial spondyloarthritis activity using a magnetic resonance imaging-based multi-region-of-interest fusion model

BACKGROUND

Identifying axial spondyloarthritis (axSpA) activity early and accurately is essential for treating physicians to adjust treatment plans and guide clinical decisions promptly. The current literature is mostly focused on axSpA diagnosis, and there has been thus far, no study that reported the use of a radiomics approach for differentiating axSpA disease activity. In this study, the aim was to develop a radiomics model for differentiating active from non-active axSpA based on fat-suppressed (FS) T2-weighted (T2w) magnetic resonance imaging (MRI) of sacroiliac joints.

METHODS

This retrospective study included 109 patients diagnosed with non-active axSpA (n = 68) and active axSpA (n = 41); patients were divided into training and testing cohorts at a ratio of 8:2. Radiomics features were extracted from 3.0 T sacroiliac MRI using two different heterogeneous regions of interest (ROIs, Circle and Facet). Various methods were used to select relevant and robust features, and different classifiers were used to build Circle-based, Facet-based, and a fusion prediction model. Their performance was compared using various statistical parameters. p < 0.05 is considered statistically significant.

RESULTS

For both Circle- and Facet-based models, 2284 radiomics features were extracted. The combined fusion ROI model accurately differentiated between active and non-active axSpA, with high accuracy (0.90 vs.0.81), sensitivity (0.90 vs. 0.75), and specificity (0.90 vs. 0.85) in both training and testing cohorts.

CONCLUSION

The multi-ROI fusion radiomics model developed in this study differentiated between active and non-active axSpA using sacroiliac FS T2w-MRI. The results suggest MRI-based radiomics of the SIJ can distinguish axSpA activity, which can improve the therapeutic result and patient prognosis. To our knowledge, this is the only study in the literature that used a radiomics approach to determine axSpA activity.

Axial Spondyloarthritis: Evolving concepts regarding the disease's diagnosis and treatment

Spondyloarthritis (SpA) is a chronic inflammatory disease that affects the axial skeleton (axSpA) and/or the peripheral joints (p-SpA) and entheses. The natural history of SpA in the decades of the 80 and 90 s involved a progressive disease with pain, spinal stiffness, ankylosis of the axial skeleton, structural damage of peripheral joints, and a poor prognosis. In the last 20 years, enormous advances in understanding and managing SpA have occurred. With the introduction of the ASAS classification criteria and MRI, early disease recognition is now possible. The ASAS criteria widened the spectrum of SpA to include all the disease phenotypes, such as radiographic (r-axSpA), non-radiographic (nr-axSpA), and p-SpA and extraskeletal manifestations. Nowadays, the treatment of SpA is based on a shared decision between patients and rheumatologists and includes non-pharmacological and pharmacological therapies. Moreover, the discovery of TNFα, IL-17, which play a pivotal role in disease pathophysiology, has revolutionized disease management. Thus, new targeted therapies and many biological agents are now available and used in SpA patients. TNFα inhibitors (TNFi), IL-17, and JAK inhibitors were proven to be efficacious, with an acceptable toxicity profile. Overall, their efficacy and safety are comparable with some differences. Sustained clinical disease remission, low disease activity, improvement of patient's quality of life, and prevention of progression of structural damage, are the results of the above interventions. The concept of SpA has changed in the last 20 years. The disease burden can be ameliorated by early and accurate diagnosis and targeting therapies.

Comparison of sacroiliac CT findings in patients with and without ankylosing spondylitis aged over 50 years

Diagnosis of axial spondyloarthritis (axSpA) is nowadays commonly made with the help of pelvic radiography or magnetic resonance imaging (MRI). However, there is an important inter-observer variability in radiography, and MRI is subject to possible false positives and is not the best modality for studying structural lesions. Conversely, pelvic computed tomography (CT) has excellent specificity and appears to be more effective than radiography for the diagnosis of ankylosing spondylitis (AS). However, its findings in patients over 50 years of age have not yet been studied. The objectives of this study were to describe the CT characteristics of sacro-iliac joints (SIJ) and the presence of intra-articular gas in patients with AS aged over 50 years and to compare them with controls of the same age and sex. This two-center, cross-sectional, observational study was performed using the medical records of the rheumatology departments of two University Hospitals. We included patients with a clinical diagnosis of axSpA, who had both definite radiographic sacroiliitis according to the modified New York criteria and met the ASAS 2009 criteria for axSpA (that is, AS), and who had undergone any CT scan including the whole SIJ. Each patient was matched for age and sex to a control randomly selected on the Picture Archiving and Communication System (PACS), symptomatic or asymptomatic, and without spondyloarthritis. For each individual, CT scans were interpreted blindly by two independent rheumatologists and scored for joint space narrowing (JSN), erosions, sclerosis, intra-articular gas, and diffuse idiopathic skeletal hyperostosis (DISH). Ninety patients and 90 controls were included in the study. The rates of positive JSN, erosion, and sclerosis scores were higher in the AS group (91% vs. 21%, p < 0.0001; 31% vs. 2%, p < 0.0001; 27% vs. 13%, p = 0.03, respectively), but the rates of intra-articular gas and DISH were higher in the control group (24% vs. 68%, p < 0.0001; 7% vs. 33%, p < 0.0001, respectively). 58% of patients had complete bilateral ankylosis. A total of 83 (92.2%) patients had a CT scan considered positive for AS, compared with only seven controls (7.8%). Sclerosis and erosions were predominantly on the anterosuperior part and iliac side of the joint in controls and were more diffuse in patients with AS. CT findings in patients with AS over 50 years of age are mostly represented by changes in the joint space; patients with AS have more erosions and sclerosis changes, but less intra-articular gas than controls.

A comparison of the clinical characteristics and quality of life of male and female patients with non-radiographic axial spondyloarthritis

OBJECTIVE

The aim of this study was to compare the clinical characteristics and quality of life of male and female patients with non-radiographic axial spondyloarthritis (nraxSpA) to determine the differences and similarities.

PATIENTS AND METHODS

The study included 100 patients, comprising 50 males and 50 females, aged 18-65 years, who presented at the Rheumatology Clinic and were diagnosed with nr-axSpA according to the Assessment of Spondyloarthritis International Society (ASAS) criteria. The data of patient age, gender, body mass index, disease duration, and drugs used were recorded. Disease activity was evaluated with the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), mobility with the Bath Ankylosing Spondylitis Metrology Index (BASMI), functional status with the Bath Ankylosing Spondylitis Functional Index (BASFI), enthesitis with the Maastricht Ankylosing Spondylitis Enthesitis Score (MASES), and quality of life with the Ankylosing Spondylitis Quality of Life (ASQoL). The patients with nr- axSpA were separated into groups as male and female, and the demographic and clinical data were compared.

RESULTS

The mean age of female patients was determined to be statistically significantly higher than that of the male patients (39.04 ± 0.70 vs. 34.28 ± 9.26 years, p:0.014). A statistically greater number of male patients were smokers (p:0.007). The disease duration and time since diagnosis were determined to be significantly longer in females than in males (p:0.029, p:0.004). Peripheral arthritis was determined at a significantly higher rate in females (p < 0.001). The MASES score was 2.66 ± 3.46 in females and 0.52 ± 1.03 in males, and the difference was statistically significant (p < 0.001). The BASDAI score was significantly higher in females (3.74 ± 2.35) than in males (2.88 ± 1.95) (p:0.05). No statistically significant difference was determined between the two groups in respect of BASFI, BASMI, ASQoL, and other parameters.

CONCLUSION

The results showed older age, longer disease duration and time to diagnosis, higher rates of peripheral arthritis, and higher MASES and BASDAI scores in the female patients. Thus, there are some differences between male and female patients. Further studies should determine what kind of changes these differences will make in the clinical status, follow-up and treatment of patients.

A mixed methods study to uncover impediments to accurate diagnosis of nonradiographic axial spondyloarthritis in the USA

INTRODUCTION/OBJECTIVES

Delayed diagnosis of axial spondyloarthritis (axSpA) is well documented; little is known about the diagnostic journey and impediments for US patients with nonradiographic axSpA (nr-axSpA). It is hypothesized that impediments are varied and exist at both the healthcare provider (HCP) and patient levels. This study aims to understand patient experiences and contributors to delayed nr-axSpA diagnosis in the USA.

METHOD

Interviews of adults with rheumatologist-diagnosed nr-axSpA, recruited through Spondylitis Association of America outreach and patient panels, and of rheumatologists, explored the diagnostic journey and diagnostic barriers. Emerging themes were further explored in an online patient survey. A multiple logistic regression analysis evaluated the main outcome variable, factors affecting time to nr-axSpA diagnosis.

RESULTS

Interviews were conducted with 25 patients and 16 rheumatologists. Survey responses from 186 eligible patients revealed median time from symptom onset to diagnosis of nr-axSpA was 3.25 years. Delayed diagnosis was significantly more likely for women and people in rural areas. Most patients consulted ≥4 different types of HCPs before a rheumatologist and ≥2 rheumatologists before diagnosis. Impediments to timely diagnosis included insidious chronic pain; episodic symptom patterns attributed to activity; symptoms other than chronic lumbosacral back pain requiring medical consultation; and unfamiliarity with and misperceptions about nr-axSpA among HCPs, radiologists, and rheumatologists.

CONCLUSIONS

Delayed nr-axSpA diagnosis is common and reflects HCP knowledge gaps and frequent patient presentation with dominant nonaxial symptoms. Targeted HCP education, research into early disease patterns, and interventions sensitive to the broader spectrum of nr-axSpA manifestations are needed to improve timely diagnosis. Key Points • Patients with nr-axSpA often see multiple types of HCPs, and multiple rheumatologists, before receiving a diagnosis. • Both patients and HCPs are unfamiliar with nr-axSpA and its symptoms, lacking understanding that nr-axSpA can occur in young people, females, and those presenting with normal x-rays. • Disease recognition by nonrheumatology HCPs is key for early referral. • Education on cardinal features, epidemiology, burden, and benefits of timely nr-axSpA diagnosis is warranted for HCPs who commonly manage back pain.

HLA-B27 status and inflammatory MRI lesions of the sacroiliac joints: a post hoc analysis in patients without axial spondyloarthritis

OBJECTIVE

The assessment of inflammatory and structural lesions in the sacroiliac joint (SIJ) is crucial in axial spondyloarthritis (axSpA). HLA-B27 status plays an important role in axSpA diagnosis and has been linked to MRI lesion burden in the general population. We aimed to investigate the sex-specific influence of HLA-B27 status on inflammatory and structural MRI findings in patients with low back pain of non-inflammatory origin.

METHODS

This post hoc analysis included 139 non-axSpA patients (90 women) with chronic low back pain. Two readers scored MRIs of the SIJ for the presence of sclerosis, erosion, fat metaplasia, bone marrow oedema (BMO) and ankylosis. Frequencies and extent of lesions were compared regarding the HLA-B27 status using χ2 tests and t-tests. Regression models to assess the sex-dependent influence of HLA-B27 on lesion burden were computed.

RESULTS

HLA-B27 was positive in 33 women (36.7%) and 23 men (46.9%). The overall occurrence of all SIJ lesions did not differ in HLA-B27 negative and positive individuals. There were no significant differences in the extent of lesions considering the HLA-B27 positivity, for erosion (mean sum score (MSS) of 0.91 vs 0.48; p=0.144), sclerosis (MSS 1.65 vs 1.88; p=0.576), fat metaplasia (MSS 0.56 vs 0.27; p=0.425), BMO (MSS 0.75 vs 0.59; p=0.460) and ankylosis (MSS 0.06 vs 0.04; p=0.659).

CONCLUSION

HLA-B27 status has no significant influence on the occurrence and extent of SIJ lesions in patients with low back pain of non-inflammatory origin in either men or women.

Magnetic resonance imaging in spondyloarthritis: Friend or Foe?

Magnetic resonance imaging (MRI) has emerged as a valuable tool for early detection and of axial spondyloarthritis (axSpA). A standardized imaging acquisition protocol, aligned with the current state-of-the-art, is crucial to obtain MRI scans that meet the diagnostic quality requirements. It is important to note that certain lesions, particularly bone marrow edema (BME), can be induced by mechanical stress or be a manifestation of another non-inflammatory disorder and may mimic the characteristic findings of axSpA on MRI. Therefore, a thorough assessment of MRI lesions, considering their localization and presence of highly specific features such as erosions and backfill, becomes imperative. Additionally, the application of additional imaging modalities, when necessary, can contribute to the differentiation of axSpA from other conditions that may exhibit similar MRI findings. This review provides recommendations on how to perform MRI in daily clinical practice and how to interpret finding from the differential diagnostic point of view.

Clash of the titans: Current CT and CT-like imaging modalities in sacroiliitis in spondyloarthritis

Sacroiliitis is characterised by active and structural changes of the joint. While the Assessment of Spondyloarthritis international Society (ASAS) classification criteria stress the importance of bone marrow inflammation, recent reports suggest that osteitis can occur in various diseases, mechanical conditions and healthy individuals. Thus, structural lesions such as joint surface erosion and ankylosis are important factors for differential diagnosis. Various imaging modalities are available to examine these changes. However, computed tomography (CT) is generally considered the reference standard. Nonetheless, recent advances in magnetic resonance imaging (MRI) allow for direct bone imaging and the reconstruction of CT-like images that can provide similar information. This way, the ability of MRI to detect and measure structural lesions is strengthened. The aim of this review is to provide an overview of the pros and cons of CT and CT-like imaging modalities in sacroiliitis.

Challenges in the diagnosis of axial spondyloarthritis

With back pain as one of the most common complaints in the population and with no single disease feature with sufficient sensitivity and specificity to diagnose axial spondyloarthritis (axSpA) on its own, diagnosing axSpA can be challenging. In this article, we discuss clinical, laboratory, and imaging spondyloarthritis features that can be used in diagnosis and explain the general principles underlying an axSpA diagnosis. Moreover, we discuss three pitfalls to avoid when diagnosing axSpA: i) using classification criteria as diagnostic criteria, ii) making a diagnosis by simple counting of spondyloarthritis features, and iii) over-reliance on imaging findings. Finally, we have some advice on how to build diagnostic skills and discuss new developments that may help facilitate the diagnosis of axSpA in the future.

The bone marrow side of axial spondyloarthritis

Spondyloarthritis (SpA) is characterized by the infiltration of innate and adaptive immune cells into entheses and bone marrow. Molecular, cellular and imaging evidence demonstrates the presence of bone marrow inflammation, a hallmark of SpA. In the spine and the peripheral joints, bone marrow is critically involved in the pathogenesis of SpA. Evidence suggests that bone marrow inflammation is associated with enthesitis and that there are roles for mechano-inflammation and intestinal inflammation in bone marrow involvement in SpA. Specific cell types (including mesenchymal stem cells, innate lymphoid cells and γδ T cells) and mediators (Toll-like receptors and cytokines such as TNF, IL-17A, IL-22, IL-23, GM-CSF and TGFβ) are involved in these processes. Using this evidence to demonstrate a bone marrow rather than an entheseal origin for SpA could change our understanding of the disease pathogenesis and the relevant therapeutic approach.

Data-Driven Magnetic Resonance Imaging Definitions for Active and Structural Sacroiliac Joint Lesions in Juvenile Spondyloarthritis Typical of Axial Disease: A Cross-Sectional International Study

OBJECTIVE

We aimed to determine quantitative sacroiliac (SI) joint magnetic resonance imaging (MRI) cutoffs for active and structural lesions that will be incorporated as imaging domains in classification criteria of axial disease in juvenile spondyloarthritis (SpA).

METHODS

MRI scans from an international cross-section of juvenile SpA patients were reviewed by 6 musculoskeletal imaging experts blinded to clinical details. Raters globally assessed the presence/absence of lesions typical of axial SpA and performed SI joint quadrant- or joint-based scoring. Sensitivity and specificity of lesion cutoffs were calculated using a rater majority (≥4 of 6 raters) on a global assessment of the presence/absence of active or structural lesions typical of axial SpA with high confidence as the reference standard. Cutoffs were validated in an independent cohort.

RESULTS

Imaging from 243 subjects, 61% male, median age 14.9 years, had sequences available for detailed MRI scoring. Optimal cutoffs for defining lesions typical of axial disease in juvenile SpA were: 1) inflammatory lesion: bone marrow edema in ≥3 SI joint quadrants across all SI joint MRI slices (sensitivity 98.6%, specificity 96.5%); 2) structural lesions: erosion in ≥3 quadrants or sclerosis or fat lesion in ≥2 SI joint quadrants or backfill or ankylosis in ≥2 joint halves across all SI joint MRI slices (sensitivity 98.6%, specificity 95.5%). Sensitivity and specificity of the optimal cutoffs in the validation cohort were excellent.

CONCLUSION

We propose data-driven cutoffs for active inflammatory and structural lesions on MRI typical of axial disease in juvenile SpA that have high specificity and sensitivity using central imaging global assessment as the reference standard and excellent reliability.

Data-Driven Magnetic Resonance Imaging Definitions for Active and Structural Sacroiliac Joint Lesions in Juvenile Spondyloarthritis Typical of Axial Disease: A Cross-Sectional International Study

OBJECTIVE

We aimed to determine quantitative sacroiliac (SI) joint magnetic resonance imaging (MRI) cutoffs for active and structural lesions that will be incorporated as imaging domains in classification criteria of axial disease in juvenile spondyloarthritis (SpA).

METHODS

MRI scans from an international cross-section of juvenile SpA patients were reviewed by 6 musculoskeletal imaging experts blinded to clinical details. Raters globally assessed the presence/absence of lesions typical of axial SpA and performed SI joint quadrant- or joint-based scoring. Sensitivity and specificity of lesion cutoffs were calculated using a rater majority (≥4 of 6 raters) on a global assessment of the presence/absence of active or structural lesions typical of axial SpA with high confidence as the reference standard. Cutoffs were validated in an independent cohort.

RESULTS

Imaging from 243 subjects, 61% male, median age 14.9 years, had sequences available for detailed MRI scoring. Optimal cutoffs for defining lesions typical of axial disease in juvenile SpA were: 1) inflammatory lesion: bone marrow edema in ≥3 SI joint quadrants across all SI joint MRI slices (sensitivity 98.6%, specificity 96.5%); 2) structural lesions: erosion in ≥3 quadrants or sclerosis or fat lesion in ≥2 SI joint quadrants or backfill or ankylosis in ≥2 joint halves across all SI joint MRI slices (sensitivity 98.6%, specificity 95.5%). Sensitivity and specificity of the optimal cutoffs in the validation cohort were excellent.

CONCLUSION

We propose data-driven cutoffs for active inflammatory and structural lesions on MRI typical of axial disease in juvenile SpA that have high specificity and sensitivity using central imaging global assessment as the reference standard and excellent reliability.

Axial Spondyloarthritis and Diagnostic Challenges: Over-diagnosis, Misdiagnosis, and Under-diagnosis

PURPOSE OF REVIEW

This article aims to review the challenges in axial spondyloarthritis diagnosis and identify the possible contributing factors.

RECENT FINDINGS

The inability to reach an accurate diagnosis in a timely fashion can lead to treatment delays and worse disease outcomes. The lack of validated diagnostic criteria and the misuse of the currently available classification criteria could be contributing. There is also significant inter-reader variability in interpreting images, and the radiologic definitions of axial spondyloarthritis continue to be re-defined to improve their positive predictive value. The role of inflammatory back pain features, serologic biomarkers, genetics, and their diagnostic contribution to axial spondyloarthritis continues to be investigated. There is still a significant amount of delay in the diagnosis of axial spondyloarthritis. Appreciating the factors that contribute to this delay is of utmost importance to close the gap. It is similarly important to recognize other conditions that may present with symptoms that mimic axial spondyloarthritis so that misdiagnosis and wrong treatment can be avoided.

Sex Disparities of the Sacroiliac Joint: Focus on Joint Anatomy and Imaging Appearance

The sacroiliac joint (SIJ) is an anatomically complex joint which, as a functional unit with the pelvis and spine, is of decisive biomechanical importance for the human body. It is also a commonly overlooked source of lower back pain. Like the entire bony pelvis, the SIJ exhibits major sexual dimorphisms; thus, the sex-dependent evaluation of this joint is becoming increasingly important in clinical practice, both anatomically with joint shape variations and biomechanical differences as well as in terms of image appearance. The influence of the SIJ shape, which differs in women and men, is crucial for the different biomechanical joint properties. These differences are important in the development of joint diseases at the SIJ, which shows a specific difference between the sexes. This article aims to provide an overview of sex disparities of the SIJ regarding different anatomical and imaging appearances to further understand the insights into the interplay of sex differences and SIJ disease.

Fetuin-A: A Novel Biomarker of Bone Damage in Early Axial Spondyloarthritis. Results of an Interim Analysis of the SPACE Study

Our study aimed to evaluate the association between fetuin-A levels and the presence of radiographic sacroiliitis and syndesmophytes in patients with early axial spondyloarthritis (axSpA) and to identify potential predictors of radiographic damage in the sacroiliac joints (SIJs) after 24 months. Patients diagnosed with axSpA in the Italian cohort of the SpondyloArthritis-Caught-Early (SPACE) study were included. Physical examinations, laboratory tests (including fetuin-A), SIJ,+ and spinal X-rays and MRIs at T0 (diagnosis) and at T24 were considered. Radiographic damage in the SIJs was defined according to the modified New York criteria (mNY). Fifty-seven patients were included in this analysis (41.2% male, median (interquartile range), chronic back pain [CBP] duration of 12 (8-18) months). Fetuin-A levels were significantly lower in patients with radiographic sacroiliitis compared to those without at T0 (207.9 (181.7-215.9) vs. 239.9 (217.9-286.9), respectively, p < 0.001) and at T24 (207.6 (182.5-246.5) vs. 261.1 (210.2-286.6) µg/mL, p = 0.03). At T0, fetuin-A levels were significantly higher in non-smokers, in patients with heel enthesitis and in those with a family history of axSpA; fetuin-A levels at T24 were higher in females, in patients with higher ESR or CRP at T0 and in those with radiographic sacroiliitis at T0. Fetuin-A levels at T0 were independently negatively associated with the likelihood of radiographic sacroiliitis (OR = 0.9 per 10-unit increase (95% CI 0.8, 0.999), p = 0.048); but not with the presence of syndesmophytes. After adjustment for confounders, fetuin-A levels at T0 and T24 were also negatively associated with mNY at T0 (β -0.5, p < 0.001) and at T24 (β -0.3, p < 0.001), respectively. Among other variables at T0, fetuin-A levels did not achieve statistical significance in predicting mNY at T24. Fetuin-A levels were negatively associated with radiographic damage of the SIJs, but not of the spine, in early axSpA and after 2 years of follow-up. Our findings suggest that fetuin-A levels may serve as a biomarker to identify patients with a higher risk of developing severe disease and early structural damage.

Diagnostics of Sacroiliac Joint Differentials to Axial Spondyloarthritis Changes by Magnetic Resonance Imaging

The diagnosis of axial spondyloarthritis (axSpA) is usually based on a pattern of imaging and clinical findings due to the lack of diagnostic criteria. The increasing use of magnetic resonance imaging (MRI) of the sacroiliac joints (SIJ) to establish the diagnosis early in the pre-radiographic phase has resulted in a shift in the paradigm with an increasing frequency of axSpA diagnoses and a changed sex distribution. Non-radiographic axSpA affects males and females nearly equally, whereas ankylosing spondylitis predominantly occurs in males. The MRI-based increasing frequency of axSpA in women is mainly due to the presence of subchondral bone marrow edema (BME) on fluid-sensitive MR sequences, which may be a non-specific finding in both women and men. Due to the somewhat different pelvic tilt and SIJ anatomy, women are more prone than men to develop strain-related MRI changes and may have pregnancy-related changes. Awareness of non-specific subchondral BME at the SIJ is important as it can imply a risk for an incorrect SpA diagnosis, especially as the clinical manifestations of axSpA may also be non-specific. Knowledge of relevant MRI and clinical features of differential diagnoses is needed in the diagnostic workout of patients with suspected axSpA considering that non-SpA-related SIJ conditions are more common in patients with low back or buttock pain than axSpA sacroiliitis. The purpose of this review was to present current knowledge of the most frequent differential diagnoses to axSpA sacroiliitis by MRI taking the clinical characteristics into account.

Challenges in non-radiographic axial spondyloarthritis

Non-radiographic axial spondyloarthritis (nr-axSpA) is part of the spectrum or continuum of axSpA and is characterized by the absence of definite structural damage in the sacroiliac joints. The introduction of the concept of axSpA with two - non-radiographic and radiographic - stages stimulated activities related to the improvement of early diagnosis and treatment of this disease, but also opened a number of controversial topics in the field. In this article, we are discussing several challenges related to the concept of nr-axSpA, the diagnosis, and the treatment in the historical context and in the light of the recent data.

Magnetic resonance imaging findings related to sacroiliac joint pain in high-performance athletes

BACKGROUND

Sacroiliac joint (SIJ) dysfunction in athletes affects competitiveness. However, the pathology and imaging features have not been clarified.

OBJECTIVE

To clarify the association between SIJ pain and MRI findings in high-performance athletes.

METHODS

Fifty-two Japanese high-performance athletes with or without SIJ pain were recruited. MRI short tau inversion recovery (STIR) semi-coronal and semi-axial images of their SIJs were taken. The relationships between high-signal changes in MRI-STIR and SIJ pain and pain duration were investigated. Six athletes with continuous SIJ pain were prospectively followed.

RESULTS

The proportion of athletes with high-signal changes in the SIJ was significantly higher among athletes with SIJ pain for one month or more (76.9%, 10/13) than among athletes with SIJ pain for less than one month (18.2%, 2/11) and among athletes without SIJ pain (28.6%, 8/28). High-signal changes on painful SIJs were most often present in the sacrum. In three of the six athletes who were prospectively followed, the high-signal area and intensity on MRI both diminished as their symptoms improved.

CONCLUSIONS

High-signal changes of the SIJ on MRI-STIR images in high-performance athletes may reflect their SIJ pain.

Facet Joint Involvement in Early MRI Positive Axial Spondyloarthritis

Background The disease course of non-radiographic axial spondyloarthritis (nr-axSpA), usually detected by magnetic resonance imaging (MRI), is often unclear at the time of diagnosis. We investigated which MRI findings in the sacroiliac joints (SIJs) and lumbar spine including the facet joints can be observed over a two-year period in patients with newly diagnosed active inflammatory lesions in the SIJs fufilling the Assessment of SpondyloArthritis International Society criteria (ASAS) for Axial Spondyloarthritis (axSpA).

Methods Patients (n=56, age<45 years, 30 female and 26 male, symptom duration 3–30 months) consecutively diagnosed with unilateral or bilateral sacroiliitis through MRI during an 18-month period and meeting the ASAS criteria for axial SpA were followed up for two years. Clinical examination, laboratory tests and an MRI of the sacroiliac joints (SIJs), lumbar spine and facet joints were performed at diagnosis (t0), after one year (t1) and after two years (t2).

Results At t0, 31 patients (55%) with a bone marrow edema (BME) in the SIJs already had detectable changes in the facet joints, including signs of inflammation or degenerative changes. At t2, patients with facet joint involvement in t0 not only had more significant changes in the SIJs but also significantly more changes in the vertebral bodies, including BME, fat lesions and vertebral body erosions than patients without changes in the facet joints at t0. All vertebral changes described might be potential indicators of progression to radiographic axSpA (r-axSpA). These MRI findings are seen more frequently over a short period of time than previously thought.

Conclusions MRI progression in the SIJs over a two-year period is associated with increasing damage to the facet joints and vertebral bodies. Involvement of the facet joints in the early stages of the disease may indicate increasing changes in the vertebral bodies and thus a less favourable course of axSpA.

Computed tomography-based assessment of radiographic progression in spine and sacroiliac joints after pregnancy in women with radiographic axial spondyloarthritis

Background

Mechanical stress are one of the pathogenesis of axial spondyloarthritis (axSpA). During pregnancy, the mechanical overload on the spine and pelvis increases due to gravid uterus. We aimed to investigate whether pregnancy affects radiographic progression in patients with radiographic axSpA (r-axSpA) based on computed tomography (CT) evaluations.

Materials and methods

This retrospective study included women with r-axSpA aged 19-49 years who underwent at least two CT evaluations of the whole spine and/or sacroiliac joints (SIJs) at intervals of 2-4 years. To compare radiographic progression after delivery, we classified the patients into two groups: delivery group and controls. The delivery group was restricted to women who had the first CT ∼2 years before delivery and the second CT ∼2 years after delivery. The CT Syndesmophyte Score (CTSS) (0-522) and SIJ scores (0-40) were used to evaluate spinal syndesmophytes and erosion, joint space narrowing, and sclerosis of the SIJs.

Results

A total of 21 women in the delivery group and 38 women in the control group were included. The median (Q1-Q3) CTSS at baseline in the delivery group and controls was 19 (16-23) and 20 (13.25-27.75), and the median progression was 1 (0-3) and 0 (0-1) during the median 2.9-year follow-up, respectively. The median (Q1-Q3) SIJ score at baseline in the delivery group and controls was 13 (8-22) and 11 (6-22), and the median progression was 1.5 (0-3) and 1 (0-2), respectively. Using cut-off 0.5, 52.9, and 61.9% of r-axSpA patients and 39.3 and 44.4% of controls showed progression of whole spine and SIJs, respectively. However, no difference in proportion of spinal and SIJ progression and absolute score changes per time point was observed between two groups. Moreover, the SIJ score changes were comparable according to the delivery method.

Conclusion

Pregnancy and delivery do not affect the radiographic progression of the spine and SIJs in women with r-axSpA assessed by CT.

Progression From Subclinical Inflammation to Overt Spondyloarthritis in First-Degree Relatives of Patients in Association With HLA-B27: The Pre-Spondyloarthritis Cohort

OBJECTIVE

As first-degree relatives (FDRs) of HLA-B27-positive patients with axial spondyloarthritis (SpA) have an increased risk of developing axial SpA, the objectives were 1) to evaluate the presence of highly specific imaging features as well as clinical signs of SpA at baseline and after 1 year of follow-up, and 2) to describe the evolution toward clinical disease within 1 year of follow-up in a cohort of seemingly healthy FDRs of HLA-B27-positive axial SpA patients.

METHODS

The Pre-SpA cohort is a 5-year prospective inception cohort of seemingly healthy FDRs of HLA-B27-positive axial SpA patients. Clinical and imaging features were collected and recorded.

RESULTS

At baseline, 19% of the FDRs reported inflammatory back pain, 32% current arthralgia, 3% arthritis (ever), 5% enthesitis (ever), and 1% dactylitis (ever), and 3% had an extraarticular manifestation. C-reactive protein level was elevated in 16%, and erythrocyte sedimentation rate was elevated in 7%. On magnetic resonance imaging (MRI) views of sacroiliac joints, 10% had a Spondyloarthritis Research Consortium of Canada score of ≥2, 4% had a score of ≥5, and 4% had deep lesions. In total, 1% fulfilled the modified New York criteria for radiographic sacroiliitis. Clinical, MRI, and acute phase findings were equally distributed between HLA-B27-positive and -negative FDRs. After 1 year of follow-up, clinical parameters did not change on the group level, but 6% of the FDRs were clinically diagnosed with axial SpA, of whom 86% were HLA-B27-positive.

CONCLUSION

Features associated with SpA or imaging abnormalities were found in up to 32% of seemingly healthy FDRs, with an equal distribution between HLA-B27-positive and -negative FDRs. Progression to clinical axial SpA within 1 year of follow-up was mainly observed in HLA-B27-positive FDRs.

Diffuse Idiopathic Skeletal Hyperostosis and Ankylosing Spondylitis: A Challenging Case and Review of the Literature

Background

Diffuse idiopathic skeletal hyperostosis and spondyloarthritis share similarities in clinical and radiological findings. In this article, we report a case of overlapping of these two hyperostotic diseases followed by an extensive narrative review of the literature focusing on the gray areas in the diagnosis of diffuse idiopathic skeletal hyperostosis.

Case description

We report the case of simultaneous diffuse idiopathic skeletal hyperostosis and ankylosing spondylitis in a 57-year-old man. The diagnosis was made after many collegial meetings based on solid radiological arguments.

Conclusion

Review of the literature reveals many uncertainties in the diagnosis of diffuse idiopathic skeletal hyperostosis, especially in the radiological evaluation of sacroiliac joints. Diffuse idiopathic skeletal hyperostosis and ankylosing spondylitis frequently overlap in important radiological features leading to diagnostic ambiguity and they can also co-exist in the same patient.

Spine abnormalities associated with bone edema on sacroiliac joints MRI in patients with non-inflammatory chronic back pain

OBJECTIVE

To investigate whether bone marrow edema (BME) fulfilling the ASAS definition of magnetic resonance imaging (MRI) sacroiliitis is associated with non-inflammatory spine abnormalities in patients with definite mechanical chronic back pain (CBP).

METHODS

Patients with definite mechanical CBP, according to the physician, started before the age of 45 and be lasting for more than 3months but less than 3years underwent a protocolized MRI and radiographs of sacroiliac joint (SIJ) and spine. BME and structural changes were scored, by three readers, for SIJ as well as non-inflammatory abnormalities for spine, including degenerative lesions and static disorders. Univariate analysis by Chi² test was performed to search a statistical association between BME fulfilling the ASAS definition of MRI sacroiliitis and the presence of at least one non-inflammatory spine abnormality.

RESULTS

A total of 94 patients were analyzed, 27 (29%) patients had BME and 16 (17%) patients had BME fulfilling the ASAS definition of MRI sacroiliitis; 86 (91.5%) patients had at least one non-inflammatory spine abnormality which are associated into 3 distinct clusters. BME was slightly more frequent at the lower and posterior part of the SIJ. MRI sacroiliitis was associated with interspinous bursitis, facet joint effusion and lateral spinal deviation and was more likely in patients with at least one non-inflammatory spine abnormality (OR: 4.96, 95% CI [1.47; 16.72]).

CONCLUSIONS

BME fulfilling the ASAS definition of MRI sacroiliitis is significantly associated with non-inflammatory spine abnormalities in patients with mechanical CBP.

[CME Rheumatology 26: Bone Marrow Edema of the Sacro-Iliac Joint = Spondyloarthritis? What the General Practicioner Should Know]

CME Rheumatology 26: Bone Marrow Edema of the Sacro-Iliac Joint = Spondyloarthritis? What the General Practicioner Should Know Abstract. Axial spondyloarthritis is a chronic inflammatory joint disease mainly involving the sacroiliac joints (ISG) and the spine. The diagnosis can be made early due to acute inflammatory changes in the ISG on magnetic resonance imaging (MRI). Radiographs of the ISG do not help in early diagnosis because structural damage is not apparent on radiographs until an advanced stage. In recent years, however, several studies have shown that bone marrow edema - hyperintense signals (= bright spots) as a possible MRI correlate for inflammation - does not specifically occur in axial spondyloarthritis, but can also be seen in healthy people, athletes, people with high mechanical stress (e.g. military recruits) and postpartum women. The diagnosis of axial spondyloarthritis should therefore never be based solely on an MRI finding, but must always include the overall clinical context.