MRI for diagnosis of axial spondyloarthritis: major advance with critical limitations 'Not everything that glisters is gold (standard)'

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.

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.

Sacroiliac joint beyond sacroiliitis-further insights and old concepts on magnetic resonance imaging

The sacroiliac joint (SIJ) is an amphiarthrosis composed of a posterior syndesmosis and an anterior cartilaginous portion, with limited yet present mobility. Its main function is to transmit the load from the axial skeleton to the lower limbs and vice-versa; it is susceptible to early mechanical and degenerative changes which are much more common than inflammatory sacroiliitis. Magnetic resonance imaging (MRI) has increasingly been used to evaluate these changes, and while subchondral bone marrow edema (BME) is a common finding related to both, care must be taken when applying the ASAS research MRI definition for sacroiliitis without considering lesion BME topography, size and depth, concomitant structural damage and, of course, the clinical picture. In this review, we will discuss the anatomy and biomechanics of the SIJ, the noninflammatory causes of SIJ subchondral BME, and how these concepts combined can be used to increase our diagnostic confidence.

Certolizumab Pegol Efficacy in Patients With Non‐Radiographic Axial Spondyloarthritis Stratified by Baseline MRI and C‐Reactive Protein Status: An Analysis From the C‐axSpAnd Study

Objective

Tumor necrosis factor inhibitors (TNFi) are an effective treatment for non‐radiographic axial spondyloarthritis (nr‐axSpA). To be eligible, however, many authorities require patients with nr‐axSpA to show active sacroiliitis on magnetic resonance imaging (MRI) and/or an elevated C‐reactive protein (CRP) level, possibly resulting in a perception that patients with nr‐axSpA without both factors have only low responses to TNFi treatment. We evaluated clinical responses to certolizumab pegol (CZP) in patients with nr‐axSpA stratified by baseline MRI/CRP status.

Methods

C‐axSpAnd was a phase 3, multicenter study on CZP in adult patients with active nr‐axSpA and objective signs of inflammation. This analysis assessed efficacy of CZP over the 52‐week randomized, double‐blind, placebo‐controlled period in patients stratified into subgroups based on the presence of active sacroiliitis on MRI and CRP level at baseline.

Results

CZP‐treated patients across all MRI/CRP subgroups achieved clinical responses greater than placebo. Across outcome measures, CZP‐treated MRI+/CRP+ patients demonstrated the greatest clinical responses, but substantial improvements were also observed in CZP‐treated MRI+/CRP− and MRI−/CRP+ patients. Ankylosing Spondylitis Disease Activity Score Major Improvement response rates at week 52 among CZP‐treated patients (75.6% MRI+/CRP+; 47.5% MRI−/CRP+; and 29.7% MRI+/CRP−) were higher than rates in placebo groups (range: 3.9%‐12.5%). Assessment of SpondyloArthritis international Society 40% response, Bath Ankylosing Spondylitis Disease Activity Index, and Bath Ankylosing Spondyloarthritis Functional Index had similar response patterns, although differences between the CZP‐treated MRI/CRP subgroups were smaller. Clinical responses among CZP‐treated patients were also observed in additional subgroups, including those with low Spondyloarthritis Research Consortium of Canada MRI sacroiliac joint inflammation scores and those with normal baseline CRP levels.

Conclusion

Our findings indicate that CZP treatment benefits patients with nr‐axSpA across MRI+/CRP+, MRI−/CRP+, and MRI+/CRP− subgroups.

Similarities and differences between non-radiographic and radiographic axial spondyloarthritis: The patient perspective from the Spanish atlas

AIM

Although non-radiographic axial spondyloarthritis (EspAax-nr) is well understood within health institutions, being considered along with radiographic EspAax (EspAax-r) as part of the same disease spectrum, patient understanding is unknown. The aim is to describe the patient's knowledge of the EspAax-nr entity.

METHODS

Atlas 2017, promoted by the Spanish Federation of Spondylarthritis Associations (CEADE), aims to comprehensively understand the reality of EspAax patients from a holistic approach. A cross-sectional on-line survey of unselected patients with self-reported EspAax diagnosis from Spain was conducted. Participants were asked to report their diagnosis. Socio-demographic, disease characteristics and patient-reported outcomes (PROs) were compared between those patients self-reporting as EspAax-nr and EspAax-r.

RESULTS

634 EspAax patients participated. Mean age 45.7±10.9 years, 50.9% female and 36.1% university-educated. 35 (5.2%) self-reported as EspAax-nr. Compared to EspAax-r patients, those with EspAax-nr were more frequently women (48.6% vs 91.4%, p<0.001), had longer diagnostic delay (10.1±8.9 vs 8.5±7.6 years), higher psychological distress (GHQ-12: 7.5±4.9 vs 5.6±4.4) and similar degree of disease activity (BASDAI: 5.7±2.1 vs 5.7±2.0), and unemployment rates (20.0% vs 21.6%). 20.0% of EspAax-nr received biologics vs 36.9% of EspAax-r, p=0.043. Visits to the rheumatologist in the past year were similar in both groups (3.8±4.5 vs 3.2±3.8), while GP visits were much higher within EspAax-nr (8.0±10.7 vs 4.9±13.3 p=0.003).

CONCLUSION

For the first time, EspAax-nr characteristics and PROs have been analyzed from the patient's perspective. Both groups reported similar trends with the exception of EspAax-nr being more frequently women, younger, having longer diagnostic delay and lower use of biologic therapy.

Diagnostic delay in axial spondyloarthritis: a systematic review

Identification of axial spondyloarthritis (axSpA) remains challenging, frequently resulting in a diagnostic delay for patients. Current benchmarks of delay are usually reported as mean data, which are typically skewed and therefore may be overestimating delay. Our aim was to determine the extent of median delay patients’ experience in receiving a diagnosis of axSpA and examine whether specific factors are associated with the presence of such delay. We conducted a systematic review across five literature databases (from inception to November 2021), with studies reporting the average time period of diagnostic delay in patients with axSpA being included. Any additional information examining associations between specific factors and delay were also extracted. A narrative synthesis was used to report the median range of diagnostic delay experienced by patients with axSpA and summarise which factors have a role in the delay. From an initial 11,995 articles, 69 reported an average time period of diagnostic delay, with 25 of these providing a median delay from symptom onset to diagnosis. Across these studies, delay ranged from 0.67 to 8 years, with over three-quarters reporting a median of between 2 years and 6 years. A third of all studies reported median delay data ranging from just 2 to 2.3 years. Of seven variables reported with sufficient frequency to evaluate, only ‘gender’ and ‘family history of axSpA’ had sufficient concordant data to draw any conclusion on their role, neither influenced the extent of the delay. Despite improvements in recent decades, patients with axSpA frequently experience years of diagnostic delay and this remains an extensive worldwide problem. This is further compounded by a mixed picture of the disease, patient and healthcare-related factors influencing delay.

Key points • Despite improvements in recent decades, patients with axSpA frequently experience years of diagnostic delay. • Median diagnostic delay typically ranges from 2 to 6 years globally. • Neither ‘gender’ nor ‘family history of axSpA’ influenced the extent of diagnostic delay experienced. • Diagnostic delay based on mean, rather than median, data influences the interpretation of the delay time period and consistently reports a longer delay period.

Levels of extracellular matrix metabolites are associated with changes in Ankylosing Spondylitis Disease Activity Score and MRI inflammation scores in patients with axial spondyloarthritis during TNF inhibitor therapy

BACKGROUND/PURPOSE

In axial spondyloarthritis (axSpA) inflammation of the sacroiliac joints and spine is associated with local extracellular matrix (ECM) remodeling of affected tissues. We aimed to investigate the association of ECM metabolites with treatment response in axSpA patients treated with TNF-α inhibitory therapy for 46 weeks.

METHODS

In a prospective clinical study of axSpA patients (n=55) initiating a TNF inhibitor (infliximab, etanercept, or adalimumab), serum concentrations of formation of type I (PRO-C1), type III (PRO-C3), and type VI (PRO-C6) collagen; turnover of type IV collagen (PRO-C4), and matrix-metalloproteinase (MMP)-degraded type III (C3M) collagen, MMP-degraded type IV (C4M), type VI (C6M), and type VII (C7M) collagen, and cathepsin-degraded type X collagen (C10C), MMP-mediated metabolite of C-reactive protein (CRPM), citrullinated vimentin (VICM), and neutrophil elastase-degraded elastin (EL-NE) were measured at baseline, week 2, week 22, and week 46.

RESULTS

Patients were mostly males (82%), HLA-B27 positive (84%), with a median age of 40 years (IQR: 32-48), disease duration of 5.5 years (IQR: 2-10), and a baseline Ankylosing Spondylitis Disease Activity Score (ASDAS) of 3.9 (IQR: 3.0-4.5). Compared to baseline, PRO-C1 levels were significantly increased after two weeks of treatment, C6M levels were significantly decreased after two and 22 weeks (repeated measures ANOVA, p=0.0014 and p=0.0015, respectively), EL-NE levels were significantly decreased after 2 weeks (p=0.0008), VICM levels were significantly decreased after two and 22 weeks (p=0.0163 and p=0.0374, respectively), and CRP were significantly decreased after two and 22 weeks (both p=0.0001). Baseline levels of PRO-C1, PRO-C3, C6M, VICM, and CRP were all associated with ASDAS clinically important and major improvement after 22 weeks (ΔASDAS ≥1.1) (Mann-Whitney test, p=0.006, p=0.008, p<0.001, <0.001, <0.001, respectively), while C6M, VICM and CRP levels were associated with ASDAS clinically important and major improvement after 46 weeks (ΔASDAS ≥2.0) (p=0.002, p=0.044, and p<0.001, respectively). PRO-C1 and C6M levels were associated with a Bath AS Disease Activity Score (BASDAI) response to TNF-inhibitory therapy after 22 weeks (Mann-Whitney test, p=0.020 and p=0.049, respectively). Baseline levels of PRO-C4 and C6M were correlated with the total SPARCC MRI Spine and Sacroiliac Joint Inflammation score (Spearman's Rho ρ=0.279, p=0.043 and ρ=0.496, p=0.0002, respectively).

CONCLUSIONS

Extracellular matrix metabolites were associated with ASDAS response, MRI inflammation, and clinical treatment response during TNF-inhibitory treatment in patients with axSpA.

The association between elevated serum interleukin-22 and the clinical diagnosis of axial spondyloarthritis: A retrospective study

OBJECTIVE

There is an unmet need for a reliable biomarker for the differentiation of axial spondyloarthritis (AxSpA) from its mimickers. Serum levels of interleukin-22 (IL-22) have previously been found to be significantly elevated in patients with AxSpA compared with healthy individuals or persons with osteoarthritis.

METHODS

Consecutive patients with established or suspected AxSpA were enrolled. The clinical data, as well as results of laboratory and imaging studies, were acquired from patients' charts. The final diagnosis of definite or probable SpA, or an alternative diagnosis, was determined, and the serum levels of IL-22 were examined by enzyme-linked immunosorbent immunoassay.

RESULTS

Interleukin-22 levels were significantly higher in patients with definite AxSpA (29 patients) compared with patients with alternative diagnoses (14 patients) and healthy volunteers (16 individuals; P < 0.001 for both comparisons). The sensitivity and specificity of the serum IL-22 for the AxSpA diagnosis were 0.68 (95% CI 0.49-0.84) and 0.86 (95% CI 0.68-0.95), respectively, for the cut-off value of 5 pg/mL. In patients with AxSpA, serum IL-22 levels did not correlate with modified Stoke Ankylosing Spondylitis Spinal Score (mSASSS), Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Ankylosing Spondylitis Disease Activity Score (ASDAS), or serum C-reactive protein.

CONCLUSION

Serum IL-22 levels are elevated in patients with the clinical diagnosis of AxSpA and can potentially serve as an independent biomarker for the differentiation of AxSpA from its non-inflammatory mimickers.

Sacroiliac joint in sarcoidosis on computed tomography: a monocentric retrospective study (SISTER)

Sacroiliitis and spondyloarthritis (SpA) have been associated to sarcoidosis. Sarcoidosis bone involvement of the sacral or iliac bones has been reported to mimic SpA. We aimed to evaluate the prevalence of structural sacroiliitis and structural changes of the sacroiliac joints (SIJ) in patients with sarcoidosis by abdominal-pelvic computed tomography (AP-CT). In this monocentric retrospective study, three blinded readers evaluated AP-CT that had already been performed on patients with sarcoidosis and classified them as normal, degenerative, or inflammatory. A consensus was reached for the divergent cases. Erosion, ankylosis, and sclerosis, classically associated with sacroiliitis, were noted. SpA was defined according to the ASAS 2009 classification criteria. We identified 217 patients with proven sarcoidosis who underwent AP-CT. Only three patients had sacroiliitis by CT and four had SpA, representing 1.38% and 1.85% of the patients, respectively. Degenerative SIJs represented 28.1% of patients and were significantly associated with age, at least one pregnancy, rural lifestyle, ankylosis, diffuse idiopathic skeletal hyperostosis, sclerosis, and the presence of osteophytes. Four patients had axial bone sarcoidosis. Sacroiliitis, SpA, and degenerative changes of the SIJ have been highlighted by AP-CT in patients with sarcoidosis. Osteoarthritis of the SIJ in sarcoidosis was associated with age, pregnancy, and rural lifestyle. Further studies are needed to assess the link between SpA and sarcoidosis.

Axial spondyloarthritis

Axial spondyloarthritis (axSpA) encompasses both radiographic and non-radiographic axSpA. It is a chronic inflammatory disease with a predilection for involving the axial skeleton. The most common presenting symptoms are chronic back pain and spinal stiffness but peripheral and extra-musculoskeletal manifestations occur also frequently. The diagnosis of axSpA relies on the recognition of a clinical pattern of the disease, based on clinical, laboratory and imaging features. The Assessment in SpondyloArthritis international Society classification criteria for axSpA are valid and well implemented for research purposes. Sustained disease activity, measured by validated tools such as the Ankylosing Spondylitis Disease Activity Score, leads to irreversible structural damage and poor functioning and therefore should be abrogated. As part of the management algorithm, non-steroidal anti-inflammatory drugs remain as the first line of pharmacological treatment besides physiotherapy. As a second line, tumour necrosis factor inhibitor and interleukin-17 inhibitor are available but recently Janus kinase inhibitors have also shown efficacy in improving symptoms of the disease.

Efficacy of guselkumab on axial involvement in patients with active psoriatic arthritis and sacroiliitis: a post-hoc analysis of the phase 3 DISCOVER-1 and DISCOVER-2 studies

BACKGROUND

Guselkumab was efficacious in reducing signs and symptoms of psoriatic arthritis in the phase 3 DISCOVER-1 and DISCOVER-2 studies. We aimed to evaluate the efficacy of guselkumab in post-hoc analyses of patients with psoriatic arthritis with imaging-confirmed sacroiliitis consistent with axial involvement.

METHODS

In DISCOVER-1, 381 patients with active psoriatic arthritis (defined as ≥3 swollen joints, ≥3 tender joints, and C-reactive protein [CRP] ≥0·3 mg/dL) and in DISCOVER-2, 739 patients with active psoriatic arthritis (defined as ≥5 swollen joints, ≥5 tender joints, and CRP ≥0·6 mg/dL) were randomly allocated to receive guselkumab 100 mg every 4 weeks, guselkumab 100 mg every 8 weeks (week 0, week 4, then every 8 weeks), or placebo. These pooled, post-hoc analyses included patients with axial disease documented by previous imaging or pelvic radiography at screening consistent with sacroiliitis (confirmed by investigator). Efficacy assessments included least squares mean changes, with 95% CIs, in Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) score, modified BASDAI (mBASDAI; excluding peripheral joint pain), spinal pain, and Ankylosing Spondylitis Disease Activity Score (ASDAS), and proportions of patients achieving at least a 50% improvement in BASDAI score (BASDAI50) and achieving ASDAS responses of inactive disease (score <1·3), major improvement (change of ≥2·0), and clinically important improvement (change of ≥1·1).

FINDINGS

Of the 1120 patients in the two DISCOVER studies, 312 (28%) were included in this analysis, of whom 118 were in the placebo group, 103 were in the guselkumab every 4 weeks group, and 91 were in the guselkumab every 8 weeks group. 191 (61%) were male, and 121 (39%) were female, and the mean age was 45·1 (SD 11·2). HLA-B27 status was assessed in 190 patients; 57 (30%) were HLA-B27-positive and 133 (70%) were HLA-B27-negative. At week 24, least squares mean changes from baseline in BASDAI were -2·7 (95% CI -3·2 to -2·2) in both guselkumab groups versus -1·3 (-1·8 to -0·9) in the placebo group; similar results were observed for mBASDAI and spinal pain. Least squares mean changes in ASDAS scores at week 24 were -1·4 (95% CI -1·7 to -1·2) in both guselkumab groups and -0·7 (-0·9 to -0·5) for placebo. At week 24, 36 (38%) patients in the guselkumab every 4 weeks group and 34 (40%) of those in the guselkumab every 8 weeks group achieved BASDAI50 versus 21 (19%) of placebo patients; greater proportions of guselkumab-treated patients achieved ASDAS responses versus placebo. Across outcomes, separation from placebo was observed at week 8. Improvements with guselkumab were seen at week 24 independent of HLA-B27 status. These improvements were maintained at week 52 in the guselkumab groups.

INTERPRETATION

Patients with active psoriatic arthritis and imaging-confirmed sacroiliitis who were treated with guselkumab every 4 weeks or every 8 weeks had greater mean improvements in BASDAI and ASDAS (as early as week 8) than did placebo-treated participants, with sustained improvements at week 52.

FUNDING

Janssen Research & Development LLC.

Ixekizumab: an IL-17A inhibitor for the treatment of axial Spondylarthritis

INTRODUCTION

Axial spondyloarthritis (axSpA) is an inflammatory arthritis which affects primarily the entheses of the spine and sacroiliac joints with peripheral joint synovitis and extra-articular manifestations. In 2017, the first IL-17A inhibitor (IL-17Ai) secukinumab was approved for the treatment of radiographic axSpA not responding adequately to conventional therapies, and this was followed in 2019 by a second IL-17Ai, ixekizumab. These agents represent the first alternative class of biological treatments after the TNF inhibitor which dominated the therapeutic landscape of axSpA for over a decade.

AREAS COVERED

This review discusses the role of IL-17Ais in the treatment in axSpA focusing on the newest IL-17Ai ixekizumab. It provides a detailed overview of the drug pharmacodynamic, pharmacokinetics, and clinical trial data, including areas of future research needed in the post-marketing era.

EXPERT OPINION

Early trials of ixekizumab for axSpA have shown encouraging results and an acceptable safety profile. Future phase IV trials should focus on direct head-to-head comparisons between ixekizumab and other biologic drugs, and stratify patients according to important disease characteristics known to affect treatment response including sex, HLA-B27 status, presence of MRI bone marrow edema at baseline, disease duration and any extra-articular manifestations.

Inflammatory back pain: a concept, not a diagnosis

PURPOSE OF REVIEW

The concept of inflammatory back pain (IBP) describes a cohort of patients with chronic back pain (CBP) who have distinct clinical characteristics, rather than being a diagnosis in and of itself. IBP is a common and important feature of axial spondyloarthritis (axSpA) but this is not the only differential. This review examines the utility of IBP in both primary and secondary care settings.

RECENT FINDINGS

There are a number of suggested referral strategies for patients with suspected axSpA that include IBP. These strategies attempt to strike a balance between ensuring potential axSpA patients are not overlooked, whilst simultaneously not overwhelming secondary care services. Their success relies on the clinicians who first encounter these patients being familiar with IBP as a concept; however, it is still poorly recognized by many healthcare professionals. IBP may be helpful as part of a referral strategy; however, other clinical features, laboratory investigations and radiology must be incorporated for the final diagnostic outcome in axSpA.

SUMMARY

Delayed diagnosis is a major clinical problem in axSpA and is associated with worse clinical outcomes. When recognized and utilized correctly, IBP can be a useful tool to promote prompt referral to rheumatology services.

Musculoskeletal Imaging for Dermatologists: Techniques in the Diagnosis and Management of Psoriatic Arthritis

Psoriatic arthritis is an inflammatory condition affecting up to 30% of patients with psoriasis. Patients may experience irreversible joint damage if not treated early, and diagnostic delays of even 6 months are associated with radiographic progression and impaired function. Therefore, early detection and intervention are of critical importance in patients with psoriatic arthritis. Given that psoriasis often precedes symptoms of psoriatic arthritis, dermatologists are uniquely positioned to identify patients with psoriatic arthritis early in their disease course, before permanent damage has occurred. Several screening tools have been developed to help dermatologists identify patients who may have psoriatic arthritis, but these tools may not capture patients with subclinical disease or quantify the type and severity of the underlying tissue insult, which is often the presenting sign of psoriatic arthritis. In these cases, a combination of clinical assessment and musculoskeletal imaging (e.g., ultrasound) is required. This review summarizes three common musculoskeletal imaging techniques used in the diagnosis and management of patients with psoriatic arthritis: conventional radiography, ultrasound, and magnetic resonance imaging. Further understanding of musculoskeletal imaging will assist dermatologists in making treatment decisions and allow them to have a more active role in the detection of psoriatic arthritis.

Similarities and Differences Between Juvenile and Adult Spondyloarthropathies

Spondyloarthritis (SpA) encompasses a broad spectrum of conditions occurring from childhood to middle age. Key features of SpA include axial and peripheral arthritis, enthesitis, extra-articular manifestations, and a strong association with HLA-B27. These features are common across the ages but there are important differences between juvenile and adult onset disease. Juvenile SpA predominantly affects the peripheral joints and the incidence of axial arthritis increases with age. Enthesitis is important in early disease. This review article highlights the similarities and differences between juvenile and adult SpA including classification, pathogenesis, clinical features, imaging, therapeutic strategies, and disease outcomes. In addition, the impact of the biological transition from childhood to adulthood is explored including the importance of musculoskeletal and immunological maturation. We discuss how the changes associated with adolescence may be important in explaining age-related differences in the clinical phenotype between juvenile and adult SpA and their implications for the treatment of juvenile SpA.

PSR: Unified Framework of Parameter-Learning-Based MR Image Superresolution

Magnetic resonance imaging has significant applications for disease diagnosis. Due to the particularity of its imaging mechanism, hardware imaging suffers from resolution and reaches its limit, and higher radiation intensity and longer radiation time will cause damage to the human body. The problem is expected to be solved by a superresolution algorithm, especially the image superresolution based on sparse reconstruction has good performance. Dictionary generation is a key issue that affects the performance of superresolution algorithms, and dictionary performance is affected by dictionary construction parameters: balance parameters, dictionary size, overlapping block size, and a number of training sample blocks. In response to this problem, we propose an optimal dictionary construction parameter search method through the experiment to find the optimal dictionary construction parameters on the MR image and compare them with the dictionary obtained by multiple sets of random dictionary construction parameters. The dictionary we searched for the optimal parameters of the dictionary construction training has more powerful feature expressions, which can improve the superresolution effect of MR images.

Diagnostic performance of plain radiography for sacroiliitis in patients with suspected axial spondyloarthritis: a systematic review and meta-analysis

BACKGROUND

Plain radiography serves a pivotal role in diagnosing axial spondyloarthritis. However, a broad range of diagnostic performance of plain radiography has been reported.

PURPOSE

To perform a systematic review and meta-analysis to measure the diagnostic performance of plain radiography for sacroiliitis in patients suspected of having axial spondyloarthritis using magnetic resonance imaging (MRI) findings as the reference standard.

MATERIAL AND METHODS

Studies comparing radiography and MRI in the diagnosis of sacroiliitis in patients suspected of having axial spondyloarthritis were searched in PubMed and EMBASE. Additionally, studies analyzed SPondyloaArthritis Caught Early (SPACE), DEvenir des Spondylarthropathies Indifferenciées Récentes (DESIR), GErman Spondyloarthritis Inception Cohort (GESPIC), and South Swedish Arthritis Treatment Group (SSATG) cohorts were manually searched. Pooled sensitivity and specificity of radiography were calculated by using a bivariate random-effects model. Meta-regression analyses were performed to identify the sources of heterogeneity.

RESULTS

Eight eligible studies with 1579 patients were included. The pooled sensitivity and specificity of radiography were 0.55 (95% confidence interval [CI] = 0.40-0.69) and 0.87 (95% CI = 0.72-0.95). The meta-regression analyses showed prospective study design and criteria for MRI positivity considering only active bone marrow edema were associated with lower sensitivity.

CONCLUSION

The plain radiography showed low sensitivity and reasonable specificity in diagnosis of sacroiliitis in patients suspected of having axial spondyloarthritis.

Utility of magnetic resonance imaging in Crohn's associated sacroiliitis: A cross-sectional study

OBJECTIVE

Prevalence of sacroiliitis in Crohn's disease (CD) is variable depending on defining criteria. This study utilized standardized sacroiliac joint (SIJ) magnetic resonance imaging (MRI) to identify sacroiliitis in CD patients and its association with clinical and serological markers.

METHODS

Consecutive adult subjects with CD prospectively enrolled from an inflammatory bowel disease clinic underwent SIJ MRI. Data collected included CD duration, history of joint/back pain, human leukocyte antigen-B27 status, Bath Ankylosing Spondylitis Metrology Index (BASMI), Bath Ankylosing Spondylitis Disease Activity Index, Harvey Bradshaw Index (HBI) for activity of CD, Ankylosing Spondylitis Disease Activity Score, and various serologic markers of inflammation. Three blinded readers reviewed MRIs for active and structural lesions according to the Spondyloarthritis Research Consortium of Canada modules.

RESULTS

Thirty-three CD patients were enrolled: 76% female, 80% White, median age 36.4 years (interquartile range 27.2-49.0), moderate CD activity (mean HBI 8.8 ± SD 4.5). Nineteen subjects (58%) reported any back pain, 13 of whom had inflammatory back pain. Four subjects (12%) showed sacroiliitis using global approach and 6 (18%) met Assessment of SpondyloArthritis international Society MRI criteria of sacroiliitis. Older age (mean 51.2 ± SD 12.5 vs. 37.2 ± 14; P = .04), history of dactylitis (50.0% vs. 3.4%, P = .03) and worse BASMI (4.1 ± 0.7 vs. 2.4 ± 0.8, P ≤ .001) were associated with MRI sacroiliitis; no serologic measure was associated.

CONCLUSION

There were 12%-18% of CD patients who had MRI evidence of sacroiliitis, which was not associated with back pain, CD activity or serologic measures. This data suggests that MRI is a useful modality to identify subclinical sacroiliitis in CD patients.

Axial spondyloarthritis: concept, construct, classification and implications for therapy

The axial spondyloarthritis (axSpA) disease concept has undergone substantial change from when the entity ankylosing spondylitis was defined by the modified New York criteria in 1984. Developments in imaging, therapy and genetics have all contributed to changing the concept of axSpA from one of erosions in the sacroiliac joints to a spectrum of disease with and without changes evident on plain radiographs. Changes to the previously held concept and construct of the disease have also necessitated new classification criteria. The use of MRI, primarily of the sacroiliac joints, has substantially altered the diagnosis and differential diagnosis of axSpA. Many in the axSpA community believe that the current classification criteria lack specificity, and the CLASSIC study is underway to examine this area. Although much about the evolving axSpA disease concept is universally agreed, there remains disagreement about operationalizing aspects of it, such as the requirement for the objective demonstration of axial inflammation for the classification of axSpA. New imaging technologies, biomarkers and genetics data will probably necessitate ongoing revision of axSpA classification criteria. Advances in our knowledge of the biology of axSpA will settle some differences in opinion as to how the disease concept is applied to the classification and diagnosis of patients.

Similarities and differences between non-radiographic and radiographic axial spondyloarthritis: The patient perspective from the Spanish atlas

AIM

Although non-radiographic axial spondyloarthritis (EspAax-nr) is well understood within health institutions, being considered along with radiographic EspAax (EspAax-r) as part of the same disease spectrum, patient understanding is unknown. The aim is to describe the patient's knowledge of the EspAax-nr entity.

METHODS

Atlas 2017, promoted by the Spanish Federation of Spondylarthritis Associations (CEADE), aims to comprehensively understand the reality of EspAax patients from a holistic approach. A cross-sectional on-line survey of unselected patients with self-reported EspAax diagnosis from Spain was conducted. Participants were asked to report their diagnosis. Socio-demographic, disease characteristics and patient-reported outcomes (PROs) were compared between those patients self-reporting as EspAax-nr and EspAax-r.

RESULTS

634 EspAax patients participated. Mean age 45.7±10.9 years, 50.9% female and 36.1% university-educated. 35 (5.2%) self-reported as EspAax-nr. Compared to EspAax-r patients, those with EspAax-nr were more frequently women (48.6% vs 91.4%, p<0.001), had longer diagnostic delay (10.1±8.9 vs 8.5±7.6 years), higher psychological distress (GHQ-12: 7.5±4.9 vs 5.6±4.4) and similar degree of disease activity (BASDAI: 5.7±2.1 vs 5.7±2.0), and unemployment rates (20.0% vs 21.6%). 20.0% of EspAax-nr received biologics vs 36.9% of EspAax-r, p=0.043. Visits to the rheumatologist in the past year were similar in both groups (3.8±4.5 vs 3.2±3.8), while GP visits were much higher within EspAax-nr (8.0±10.7 vs 4.9±13.3 p=0.003).

CONCLUSION

For the first time, EspAax-nr characteristics and PROs have been analyzed from the patient's perspective. Both groups reported similar trends with the exception of EspAax-nr being more frequently women, younger, having longer diagnostic delay and lower use of biologic therapy.

Loss and gain of bone in spondyloarthritis: what drives these opposing clinical features?

The breadth of bone lesion types seen in spondyloarthritis is unprecedented in medicine and includes increased bone turnover, bone loss and fragility, osteitis, osteolysis and erosion, osteosclerosis, osteoproliferation of soft tissues adjacent to bone and spinal skeletal structure weakness. Remarkably, these effects can be present simultaneously in the same patient. The search for a potential unifying cause of effects on the skeleton necessarily focuses on inflammation arising from the dysregulation of immune response to microorganisms, particularly dysregulation of T_H17 lymphocytes, and the dysbiosis of established gut and other microbiota. The compelling notion that a common antecedent pathological mechanism affects existing bone and tissues with bone-forming potential (entheses), simultaneously with variable effect in the former but bone-forming in the latter, drives basic research forward and focuses our awareness on the effects on these bone mechanisms of the increasing portfolio of targeted immunotherapies used in the clinic.

Update of imaging in the diagnosis and management of axial spondyloarthritis

Imaging of the spine and sacroiliac joints has acquired a central role in the diagnosis and classification of axial spondyloarthritis (axSpA) in the earliest phases of the disease. New definitions of specific imaging lesions, particularly in magnetic resonance imaging (MRI), have been recently updated and revised by the ASAS MRI working group to reach a standardized understanding and diagnosis of axSpA among rheumatologists. Recognizing the misleading pitfalls of MRI lesions and differential diagnosis also represents an essential issue in clinical practice to avoid false-positive findings and establish the diagnosis of axSpA with careful regard to the clinical context, clinical signs, and biological tests. This review summarizes the current evidence on the different imaging modalities of the sacroiliac joints and the spine with their application in the clinical setting of SpA and their main pitfalls; it also highlights the newest emerging imaging techniques.

Quantitative DCE-MRI: an efficient diagnostic technique for evaluating early micro-environment permeability changes in ankylosing spondylitis

BACKGROUND

In the management of early inflammatory joint of ankylosing spondylitis (AS), there is a need for reliable noninvasive quantitative monitoring biomarker to closely assess status of synovitis progression. Cognizant to this,studies geared on improving techniques for quantitative evaluation of micro-environment permeability of the joint space are necessary. Such improved techniques may provide tissue perfusion as important biological parameters and can further help in understanding the origin of early changes associated with AS. The purpose of this study was to prospectively evaluate the diagnostic performance and determine longitudinal relationships of early micro-environment active in the joint space of the sacroiliac joint (SIJ) with a rat model by using quantitative dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI).

METHODS

Thirty wistar male rats were randomly assigned to the model (n = 15) or control (n = 15) group. All rats underwent DCE-MRI of SIJ region at fixed time points (12, 17 and 22 weeks),between September 2018 and October 2019. Differences in permeability parameters between the two groups at the same time point were compared by using an independent samples t test. Spearman correlations of DCE-MRI parameters with different time points in model group were analyzed. All statistical analyses were performed with software.

RESULTS

At 12 weeks,the K^trans,K_ep and V_e values in the model group were slightly lower than those in control group,but all the differences were not statistically significant (p > 0.05). Compared with control group,the transfer constant (K^trans) values increased significantly at 17 weeks and 22 weeks in model group,while the rate constant (K_ep) and volume of extravascular extracellular space (V_e) significantly increased only at 22 weeks(p < 0.05). The K^trans,K_ep and V_e were positively correlated with increasing time points (r = 0.946, P<0.01 for K^trans; r = 0.945, P<0.01 for K_ep; and r = 0.832, P<0.01 for V_e).

CONCLUSION

Quantitative DCE-MRI parameters are valuable for evaluating the early longitudinal relationship of micro-environment permeability changes in the joint space of SIJ.

Recognizing Axial Spondyloarthritis: A Guide for Primary Care

Axial spondyloarthritis (axSpA) is an important cause of chronic low back pain and affects approximately 1% of the US population. The back pain associated with axSpA has a characteristic pattern referred to as inflammatory back pain (IBP). Features of IBP include insidious onset before age 45 years, association with morning stiffness, improvement with exercise but not rest, alternating buttock pain, and good response to treatment with nonsteroidal anti-inflammatory drugs. In patients with IBP, it is essential to look for other features associated with spondyloarthritis (SpA), such as enthesitis, dactylitis, peripheral arthritis, extra-articular manifestations (eg, psoriasis, uveitis, or inflammatory bowel disease), human leukocyte antigen B27 positivity, and a family history of SpA. Axial SpA is underrecognized, and a delay of several years between symptom onset and diagnosis is common. However, with new and effective therapies available for the treatment of active axSpA, early recognition and diagnosis are of critical importance. For this narrative review, we conducted a literature search of English-language articles using PubMed. Individual searches were performed to identify potential articles of interest related to axSpA (search terms: ["axSpA" OR "axial SpA" OR "axial spondyloarthritis" OR "ankylosing spondylitis"]) in combination with terms related to IBP ("inflammatory back pain" OR "IBP" OR "chronic back pain" OR "CBP" OR "lower back pain" OR "LBP"), diagnosis (["diagn∗" OR "classification"] AND ["criteria" OR "recommend∗" OR "guidelines"]), and referral ("refer∗"). No date range was formally selected, as we were interested in providing an overview of the evolution of these concepts in clinical practice. We supplemented the review with insights based on our clinical expertise. Patients with chronic back pain should be screened for IBP and other SpA features; suspicion for axSpA should trigger referral to a rheumatologist for further evaluation.

Interleukin-17A biomarker as a predictor for detection of early axial spondyloarthritis changes in patients with psoriasis

AIM

Although the pathogenic mechanisms of psoriatic arthritis (PsA) are not completely clarified, evidence suggests that interleukin 17A (IL-17A)-mediated immune responses play a pivotal role in the disease. This is best underscored by the important clinical effectiveness of IL-17A inhibitors in psoriasis treatment. We aim to investigate the predictive value of IL-17A in detecting the early axial spondyloarthropic (SpA) changes in psoriatic patients.

METHODS

The study enrolled 100 patients with psoriasis, classified into group 1, included 62 patients with only psoriatic skin lesions (Ps), and group 2 included 38 patients with PsA, and 100 age and gender matched healthy volunteers. All participants were subjected to general and local clinical examination, laboratory assessment including IL-17A in the serum by means of enzyme-linked immunosorbent assay, and axial joint radiological assessment.

RESULTS

Our study included 60 males (60%) and 40 females (40%).The positive radiological findings of early axial SpA changes were found among 30.6% of the Ps group and among 84.2% of the PsA group. There were significant differences between patients with positive magnetic resonance imaging (MRI) findings of early axial SpA and patients with negative MRI findings in both groups regarding IL-17A levels. There was a significant association between IL-17A level and early axial SpA changes in psoriatic patients with a clear cutoff point (222.5).

CONCLUSION

Our study can imply that IL-17A is a valuable, useful and low-cost biomarker in detecting early axial SpA changes in asymptomatic and nonradiographic axial SpA (nr-axial SpA) psoriatic patients that helps early management and prevent progressive axial involvement and disabilities.

Bone turnover biomarkers, disease activity, and MRI changes of sacroiliac joints in patients with spondyloarthritis

The lack of valid biomarkers in patients with spondyloarthritis (SpA) requires searching for additional options to increase sacroiliac joint (SIJ) evaluation effectiveness. We assessed the serum levels of bone turnover markers and their relationships with active and chronic changes in SIJs using magnetic resonance imaging (MRI), indices, and laboratory parameters of disease activity in SpA patients. 102 patients with SpA and 15 healthy subjects were included. Testing of serum levels of transforming growth factor-beta (TGF-β1), Wnt3, sclerostin, and Dickkopf-1 (Dkk-1) was conducted. Active inflammatory lesions in SIJs were evaluated using Spondyloarthritis Research Consortium of Canada (SPARCC) MRI SIJ score, and chronic changes using the Danish scoring method. Bath Ankylosing Spondylitis Disease Activity Index, C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), Ankylosing Spondylitis Disease Activity Scores with CRP, and ESR were used to assess disease activity. Serum levels of Dkk-1, TGF-β1, and sclerostin were significantly lower in SpA patients compared to healthy controls. The serum levels of Dkk-1 positively correlated with CRP. Dkk-1 had a significant negative correlation with Danish score. The sclerostin serum level had a weak negative correlation with the active inflammatory MRI SIJ lesions. There were positive correlations between TGF-β1 and sclerostin with Dkk-1, and negative correlation between Wnt3 and sclerostin. Dkk-1 positively correlated with CRP and negatively with chronic SIJ changes by Danish score. Sclerostin negatively correlated with the active SIJ lesions by SPARCC. This suggests that Dkk-1 and sclerostin are the most promising candidates to reveal inflammation and bone turnover in patients with SpA.

Inflammation of the Sacroiliac Joints and Spine and Structural Changes on Magnetic Resonance Imaging in Axial Spondyloarthritis: Five-year Data From the DESIR Cohort

OBJECTIVE

To test the impact of inflammation on structural changes occurring in the sacroiliac (SI) joints and the spine detected on magnetic resonance imaging (MRI).

METHODS

Patients with early axial spondyloarthritis (SpA) from the Devenir des Spondylarthropathies Indifferérenciées Récentes (DESIR) cohort were included. MRIs of the SI joints (MRI-SI joints) and spine (MRI-spine), obtained at baseline, 2 years, and 5 years, were scored by 3 central readers. Inflammation and structural damage on MRI-SI joints and MRI-spine were defined by the agreement of ≥2 of 3 readers (binary outcomes) and by the average of 3 readers (continuous outcomes). The effect of inflammation (MRI-SI joints/MRI-spine) on damage (MRI-SI joints/MRI-spine, respectively) was evaluated in 2 models: 1) a baseline prediction model (the effect of baseline inflammation on damage assessed at 5 years); and 2) a longitudinal model (the effect of inflammation on structural damage assessed during a 5-year period).

RESULTS

A total of 202 patients were included. Both the presence of bone marrow edema on MRI-SI joints and on MRI-spine at baseline were predictive of 5-year damage (≥3 fatty lesions) on MRI-SI joints (odds ratio [OR] 4.2 [95% confidence interval (95% CI) 2.4, 7.3]) and MRI-spine (OR 10.7 [95% CI 2.4, 49.0]), respectively, when adjusted for C-reactive protein level. The association was also confirmed in longitudinal models (when adjusted for Ankylosing Spondylitis Disease Activity Score) both in the SI joints (OR 5.1 [95% CI 2.7, 9.6]) and spine (OR 15.6 [95% CI 4.8, 50.3]). Analysis of other structural outcomes (i.e., erosions) on MRI-SI joints yielded similar results. In the spine, a significant association was found for fatty lesions but not for erosions and bone spurs, which occurred infrequently over time.

CONCLUSION

We found a predictive and longitudinal association between inflammation detected on MRI and several types of structural damage detected on MRI in patients with early axial SpA, which adds to the evidence for a causal relationship.

Evaluating Inflammatory Versus Mechanical Back Pain in Individuals with Psoriatic Arthritis: A Review of the Literature

Psoriatic arthritis (PsA) is a chronic immune-mediated disease characterized by psoriatic skin and nail changes, peripheral joint inflammation, enthesitis, dactylitis, and/or axial involvement, either alone or in combination with each other. The presence of axial involvement has been shown to be a marker of PsA severity; however, there is no widely accepted definition of axial involvement in PsA (axPsA) or consensus on how or when to screen and treat patients with suspected axPsA. Chronic back pain is a prominent feature of axPsA and is thought to have a relevant role in early identification of disease. Chronic back pain can be caused by inflammatory back pain (IBP) or mechanical back pain (MBP). However, MBP can complicate recognition of IBP and delay diagnosis of axPsA. While MBP can also be associated with chronic back pain of ≥ 3 months in duration that is typical of IBP, IBP is characterized by inflammation of the sacroiliac joint and lower spine that is differentiated from MBP by key characteristic features, including insidious onset at age < 40 years, improvement with exercise but not with rest, and nighttime pain. This review discusses the differences in identification and management of IBP and MBP in patients with PsA with axPsA. The summary of available evidence highlights the importance of appropriate and timely screening, difficulties and limitations of differential diagnoses and treatment, and unmet needs in axPsA.

Psoriatic arthritis (PsA) is a long-term disease that may lead to psoriatic changes in skin and nails; inflammation of some joints, including finger and toe joints (dactylitis); inflammation of sites where tendons and ligaments connect to bone (enthesitis); and/or problems in the spine (axial involvement). Approximately 25–70% of patients with PsA have axial involvement (axPsA); this number varies because there is no widely accepted definition for axPsA. Chronic (long-lasting) back pain is a major feature of axSpA and can help doctors recognize axPsA early. Chronic back pain can be caused by inflammatory back pain (IBP) or mechanical back pain (MBP). IBP is described by back pain lasting ≥ 3 months, gradual onset at age < 40 years, improvement with exercise, no improvement with rest, pain at night (with improvement upon getting up), and changes in some laboratory test results. On the other hand, MBP is caused by a physical injury to the lower back. Both IBP and MBP can occur in patients with PsA, but they are treated in different ways. Being able to tell the difference between IBP and MBP is important to make sure that patients receive the right treatment. This review looks at the differences between IBP and MBP, screening for IBP, the difficulties and limitations of diagnosing and treating axPsA, and the needs of patients with axPsA for better diagnosis and treatment.

T2 mapping of the sacroiliac joints in patients with axial spondyloarthritis

PURPOSE

To test whether T2 mapping of the sacro-iliac joints (SIJs) might help identifying patients with spondyloarthritis.

METHOD

This study included 20 biologic-naive patients with axial spondyloarthritis (10 females; mean age: 38 ± 9years; range, 19-47) and 27 controls (16 males; mean age = 39 ± 13years; range = 28-71) who prospectively underwent SIJs MRI at 1.5 T, including a multislice multiecho spin-echo sequence. Standard MRIs were reviewed to assess the SIJs according to the Assessment of SpondyloArthritis International Society (ASAS) criteria and SPondyloArthritis Research Consortium of Canada (SPARCC) MRI index. T2 maps obtained from multiecho sequences were used to draw regions of interests in the cartilaginous part of the SIJs. Disease activity was assessed using BASDAI questionnaire. Bland-Altman method, ROC curve analysis, Chi square, Mann-Whitney U, Pearson's and Spearman's correlation coefficient were used for data analysis.

RESULTS

According to ASAS criteria, MRI was positive for sacroiliitis in 5/20 patients (25 %). Inter-observer reproducibility of T2 values was 87 % (coefficient of repeatability = 7.0; bias = 0.49; p < .001). Mean T2 values of patients (58.5 ± 4.4 ms, range: 52.6-68.2 ms) were significantly higher (p < .001) than those of controls (44.1 ± 6.6 ms, range: 33.6-67.2 ms). A T2 value of 52.51 ms yielded 100 % sensitivity and 91.7 % specificity to differentiate patients from controls. No statistically significant association/correlation was found between T2 values and BASDAI (r=-.026, p = .827), disease duration (r = .024, p = .871), SPARCC (r=-.004, p = .981), ASAS criteria (p = .476), HLA-B27-positivity (p = .139), age (r=-.2.53, p = .891), and gender (p = .404).

CONCLUSIONS

T2 relaxation times of the SIJs were significantly higher in patients than in healthy controls, making this tool potentially helpful to early identify patients with spondyloarthritis.

MRI of the sacroiliac joints in athletes: recognition of non-specific bone marrow oedema by semi-axial added to standard semi-coronal scans

OBJECTIVE

Assessment of combined semi-axial and semi-coronal SI joint MRI in two cohorts of young athletes to explore frequency and topography of non-specific bone marrow oedema (BMO), its association with four constitutional SI joint features, and potential restriction of false-positive assignments of Assessment of SpondyloArthritis International Society-defined sacroiliitis on standard semi-coronal scans alone.

METHODS

Combined semi-axial and semi-coronal SI joint MRI scans of 20 recreational runners before/after running and 22 elite ice-hockey players were evaluated by three blinded readers for BMO and its association with four constitutional SI joint features: vascular partial volume effect, deep iliac ligament insertion, fluid-filled bone cyst and lumbosacral transitional anomaly. Scans of TNF-treated spondyloarthritis patients served to mask readers. We analysed distribution and topography of BMO and SI joint features across eight anatomical SI joint regions (upper/lower ilium/sacrum, subdivided in anterior/posterior slices) descriptively, as concordantly recorded by ⩾2/3 readers on both MRI planes. BMO confirmed on both scans was compared with previous evaluation of semi-coronal MRI alone, which met the Assessment of SpondyloArthritis International Society definition for active sacroiliitis.

RESULTS

Perpendicular semi-axial and semi-coronal MRI scans confirmed BMO in the SI joint of every fourth young athlete, preferentially in the anterior upper sacrum. BMO associated with four constitutional SI joint features was observed in 20-36% of athletes, clustering in the posterior lower ilium. The proportion of Assessment of SpondyloArthritis International Society-positive sacroiliitis recorded on the semi-coronal plane alone decreased by 33-56% upon amending semi-axial scans.

CONCLUSION

Semi-axial combined with standard semi-coronal scans in MRI protocols for sacroiliitis facilitated recognition of non-specific BMO, which clustered in posterior lower ilium/anterior upper sacrum.

Mimics of axial spondyloarthritis

PURPOSE OF REVIEW

Axial spondyloarthritis (AxSpA) is a distinct clinical entity with characteristic clinical and radiographic features; however, a multitude of other metabolic, infectious and inflammatory disorders mimic it both clinically and radiographically.

RECENT FINDINGS

We present in this review article recent updates about the various disease entities and conditions that may mimic AxSpA and how to differentiate among them. The sensitivity and specificity of MRI in diagnosing AxSpA has limitations and needs to be interpreted in the context of the clinical picture. Interestingly, some recent studies have highlighted that a relatively high prevalence of bone marrow edema on pelvic MRIs in healthy volunteers which could even be categorized as having a 'positive MRI' as defined by Assessment of Spondyloarthritis International Society. Another study revealed that a substantial proportion of patients with suspected sacroiliitis were more commonly diagnosed with diseases other than inflammatory sacroiliitis. On the basis of these reports, it is prudent to request MRIs in the appropriate clinical context and interpreted with caution taking into considerations the wide differential diagnosis of such MRI changes.

SUMMARY

Highlighting the clinical pearls that differentiate disorders suspected of having sacroiliitis will lead to earlier and correct diagnosis and management; however, one must always take into considerations the radiographic and MRI findings in addition to the clinical presentations in order to make the appropriate diagnosis.

Clinical, Economic, and Humanistic Burden Associated With Delayed Diagnosis of Axial Spondyloarthritis: A Systematic Review

INTRODUCTION

Few studies have evaluated the impact of delayed diagnosis of axial spondyloarthritis (axSpA) on the overall burden of disease. The objective of this review was to evaluate the available literature on the clinical, economic, and humanistic burden of delayed diagnosis in patients with axSpA.

METHODS

This systematic literature review was conducted and reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We searched the MEDLINE and Embase databases for English-language publications of original research articles (up to July 12, 2018) and conference abstracts (January 1, 2014, to July 12, 2018) reporting studies of adult patients with delayed diagnosis of axSpA associated with clinical, economic, or humanistic burden. Retrieved publications were screened for eligibility by two independent reviewers; discrepancies were resolved by a third independent reviewer. Data were extracted by one reviewer and validated by a second independent reviewer.

RESULTS

A total of 1391 publications were retrieved, of which 21 met the inclusion criteria and were included in the analysis. Of these, 15 reported data on clinical burden, nine on economic burden, and six on humanistic burden, with eight studies reporting a combination of clinical, economic, and/or humanistic burden. Patients with a delayed diagnosis of axSpA generally had higher disease activity, worse physical function, and more structural damage than those who received an earlier diagnosis. Patients with a delayed diagnosis also had a greater likelihood of work disability and higher direct and indirect healthcare costs than those who received an earlier diagnosis. Delayed diagnosis was associated with a greater likelihood for depression, negative psychological impacts, and worse quality of life.

CONCLUSIONS

Delayed axSpA diagnosis was associated with more functional impairment, higher healthcare costs, and worse quality of life, highlighting the importance of early recognition of axSpA to reduce extensive burden on patients and society. Plain language summary available for this article.

What is axial spondyloarthritis? A latent class and transition analysis in the SPACE and DESIR cohorts

Objectives

To gain expert-judgement-free insight into the Gestalt of axial spondyloarthritis (axSpA), by investigating its ‘latent constructs’ and to test how well these latent constructs fit the Assessment of SpondyloArthritis international Society (ASAS) classification criteria.

Methods

Two independent cohorts of patients with early onset chronic back pain (SPondyloArthritis Caught Early (SPACE)) or inflammatory back pain (IBP) (DEvenir des Spondylarthopathies Indifférenciées Récentes (DESIR)) were analysed. Latent class analysis (LCA) was used to estimate the (unobserved) potential classes underlying axSpA. The best LCA model groups patients into clinically meaningful classes with best fit. Each class was labelled based on most prominent features. Percentage fulfilment of ASAS axSpA, peripheral SpA (pSpA) (ignoring IBP) or both classification criteria was calculated. Five-year data from DESIR were used to perform latent transition analysis (LTA) to examine if patients change classes over time.

Results

SPACE (n=465) yielded four discernible classes: ‘axial’ with highest likelihood of abnormal imaging and HLA-B27 positivity; ‘IBP+peripheral’ with 100% IBP and dominant peripheral symptoms; ‘at risk’ with positive family history and HLA-B27 and ‘no SpA’ with low likelihood for each SpA feature. LCA in DESIR (n=576) yielded similar classes, except for the ‘no-SpA’. The ASAS axSpA criteria captured almost all (SPACE: 98%; DESIR: 93%) ‘axial’ patients, but the ‘IBP+peripheral’ class was only captured well by combining the axSpA and pSpA criteria (SPACE: 78%; DESIR: 89%). Only 4% of ‘no SpA’ patients fulfilled the axSpA criteria in SPACE. LTA suggested that 5-year transitions across classes were unlikely (11%).

Conclusion

The Gestalt of axSpA comprises three discernible entities, only appropriately captured by combining the ASAS axSpA and pSpA classification criteria. It is questionable whether some patients with ‘axSpA at risk’ will ever develop axSpA.

The semi-automated algorithm for the detection of bone marrow oedema lesions in patients with axial spondyloarthritis

The aim of the study was to create the efficient tool for semi-automated detection of bone marrow oedema lesions in patients with axial spondyloarthritis (axSpA). MRI examinations of 22 sacroiliac joints of patients with confirmed axSpA-related sacroiliitis (median SPARCC score: 14 points) were included into the study. Design of our algorithm is based on Maksymowych et al. evaluation method and consists of the following steps: manual segmentation of bones (T1W sequence), automated detection of reference signal region, sacroiliac joint central lines and ROIs, a division of ROIs into quadrants, automated detection of inflammatory changes (STIR sequence). As a gold standard, two sets of manual lesion delineations were created. Two approaches to the performance assessment of lesion detection were considered: pixel-wise (detections compared pixel by pixel) and quadrant-wise (quadrant to quadrant). Statistical analysis was performed using Spearman's correlation coefficient. Correlation coefficient obtained for pixel-wise comparison of semi-automated and manual detections was 0.87 (p = 0.001), while for quadrant-wise analysis was 0.83 (p = 0.001). The correlation between two sets of manual detections was 0.91 for pixel-wise comparison (p = 0.001) and 0.88 (p = 0.001) for quadrant-wise approach. Spearman's correlation between two manual assessments was not statistically different from the correlation between semi-automated and manual evaluations, both for pixel- (p = 0.14) and quadrant-wise (p = 0.17) analysis. Average single slice processing time: 0.64 ± 0.30 s. Our method allows for objective detection of bone marrow oedema lesions in patients with axSpA. The quantification of affected pixels and quadrants has comparable reliability to manual assessment.

Plasma levels of H- and L-ficolin are increased in axial spondyloarthritis: improvement of disease identification

Axial spondyloarthritis (axSpA) is a chronic inflammatory disease that primarily affects the axial skeleton. A predominance of innate versus adaptive immune responses have been reported in axSpA, indicating a prominent autoinflammatory component of the disease. Little is known about the lectin pathway proteins (LPPs) of the complement system in relation to axSpA. We have investigated LPPs in patients with axSpA and control individuals. Plasma samples were obtained from a cross-sectional cohort of 120 patients with a clinical diagnosis of axSpA and from 144 age- and gender-matched controls. The plasma concentrations of 11 LPPs were measured, using sandwich-type time-resolved immunofluorometric assays in patients and controls, and related to clinical diagnosis and disease activity. Three LPPs [H-ficolin (ficolin-3), L-ficolin (ficolin-2) and collectin liver 1 (CL-L1)] were significantly higher in axSpA patients than in controls (P < 0·0001) and one LPP, collectin kidney 1 (CL-K1), was significantly lower (P < 0·0001). Further, combining H- or L-ficolin concentrations above the 75th percentile of the respective H- or L-ficolin concentration measured in controls with human leucocyte antigen (HLA)-B27 positivity yielded axSpA diagnostic specificities of 99/99% and positive likelihood ratios of 68/62, respectively. H-ficolin and L-ficolin plasma concentrations were found to be elevated in axSpA patients regardless of time since diagnosis. H-ficolin and L-ficolin may represent diagnostic biomarkers for patients with axSpA and should be further evaluated. Our results showed no association between disease activity and the measured LPP concentrations. This result might be due to the cross-sectional design, and should be further investigated.

MRI compared with low-dose CT scanning in the diagnosis of axial spondyloarthritis

OBJECTIVES

To compare the performance of conventional radiography, ldCT, and MRI in the diagnosis of sacroiliitis in suspected axial spondyloarthritis (axSpA).

METHODS

Patients presenting with > 3 months chronic back pain were assessed by axSpA-experienced rheumatologists and diagnosed as axSpA or not; axSpA patients were then considered nr-axSpA or AS using plain radiography. Non-axSpA patients were recruited as controls, and divided into non-inflammatory and inflammatory groups on the basis of inflammatory back pain and/or CRP/ESR elevation. Clinical variables, pelvic radiography, sacroiliac joint (SIJ) ldCT, and SIJ MRI were obtained.

RESULTS

A total of 121 patients were included and had SIJ radiography and ldCT, of whom 71 additionally had an SIJ MRI. These included 23 non-inflammatory controls, 21 inflammatory controls, 32 nr-axSpA cases, and 45 AS cases. Fourteen of 32 (44%) nr-axSpA patients had positive ldCT scans, 21/24 (88%) had MRI-BMO, and 11/24 (46%) had MRI-structural lesions. ldCT had high specificity with only 1/23 (4%) non-inflammatory controls being positive. MRI-BMO had the highest sensitivity for nr-axSpA, but compared with ldCT lower specificity, with 5/15 (33%) of non-inflammatory controls being positive, and similar sensitivity for AS (20/22 (91%) vs 44/44 for ldCT).

CONCLUSIONS

ldCT identifies evidence of radiographic change in a significant proportion of nr-axSpA cases and is highly specific for axSpA. MRI-BMO lesions are more sensitive than either conventional radiography or MRI-structural assessment for axSpA. The relative position of these imaging modalities in screening for axSpA needs to be reconsidered, also taking into account the costs involved.Key Points• ldCT is more sensitive for erosions or sclerosis in axSpA than plain radiography, with 44% of patients with nr-axSpA having evidence of AS-related sacroiliac joint changes on ldCT.• MRI-structural lesions are no more sensitive but are less specific for AS than ldCT.• MRI-BMO is the most sensitive test for nr-axSpA of the modalities tested but is less specific for axSpA than for ldCT.

Added Value of Anti-CD74 Autoantibodies in Axial SpondyloArthritis in a Population With Low HLA-B27 Prevalence

Axial spondyloarthritis (axSpA) is often diagnosed late due to the non-specific nature of its main symptom [chronic back pain (CBP)] and to the paucity of diagnostic markers, particularly in regions with low HLA-B27 prevalence, such as the Middle-East. We tested the performance of IgG4 and IgA anti-CD74 antibodies as an early diagnostic marker for axSpA, compared with the performance of HLA-B27, in Lebanon. Sera of axSpA patients diagnosed by the rheumatologist and also fulfilling the imaging arm of the ASAS criteria (patients) and of blood donors (BD) (controls) were analyzed for HLA-B27, IgG4 and IgA anti-CD74, blinded to clinical characteristics. Receiver Operating Characteristic curves were constructed to identify an optimal cut-off point for anti-CD74 antibodies. Diagnostic properties were calculated (sensitivity, specificity, positive, and positive predictive values (PPV, NPV), Likelihood ratios) for each marker. Forty-nine axSpA patients and 102 BD were included in the final analysis. IgA anti-CD74 correlated poorly with axSpA (Area Under the Curve (AUC) 0.657), whereas IgG4 anti-CD74 had a good discriminative value (AUC 0.837). Respectively, for HLA-B27, IgG4 anti-CD74, and the combination of both, we found a sensitivity of 33-92-33%, specificity of 96-79-98%, PPV 80-68-89%, NPV 75-95-75%, and LR+ 8.2-4.4-16.5. IgG4 anti-CD 74 were positive in 88% of HLA-B27 negative axSpA patients, and correlated with BASDAI. In this first study in a population with low HLA-B27 prevalence, IgG4 anti-CD74 antibodies combined with HLA-B27 showed higher diagnostic value than HLA-B27 alone for early axSpA. IgG4 anti-CD74 should be considered for further evaluation as an early axSpA diagnostic marker in future dedicated research, particularly in patients with CBP.

Imaging of sacroiliitis: Current status, limitations and pitfalls

The clinical need to diagnose sacroiliitis at an earlier stage has led to the sacroiliac joints being more frequently imaged, particularly with magnetic resonance imaging (MRI). This review outlines the imaging approach to sacroiliitis, emphasizing the imaging protocols, diagnostic criteria, limitations and potential mimics of MRI examination. The value of imaging-guided intervention in sacroiliac joint disease is also briefly outlined.

Clinical and Radiological Assessment in Axial Spondyloarthritis

The Assessment of SpondyloArthritis International Society (ASAS) has developed the concept of axial spondyloarthritis (SpA) in 2009. The symptoms and burden of disease of nonradiographic axial SpA and Ankylosing Spondylitis (AS) are similar and both can affect multiple organs and systems. Assessment and monitoring in SpA are, therefore, crucial. Different instruments have been developed for assessing and monitoring the wide variety of presentations in SpA. Generally, disease monitoring of patients can include patient reported outcome, clinical findings, laboratory tests, imaging, and disease activity composite scores.

Imaging in axial spondyloarthritis: Changing concepts and thresholds

Imaging is key to recognition of axial spondyloarthritis (SpA) because clinical and laboratory examinations have limited diagnostic utility. Only MRI can capture both inflammation and bone remodeling by simultaneous depiction of active and structural lesions and their anatomic location. Bone marrow edema of limited extent on the sacroiliac joint (SIJ) MRI is often nonspecific and should be interpreted along with the clinical context. Contextual interpretation of the SIJ lesion signature viewed simultaneously on fluid- and fat-sensitive MRI sequences enhances confidence in the recognition of disease. A critical re-appraisal of using pelvic radiographs in clinically suspected early spondyloarthritis is warranted because of substantial limitations. In health care settings with low threshold access to advanced imaging, MRI is the preferred modality in early SpA. CT has recently advanced spinal outcome research, but substantial radiation exposure in young patients with spondyloarthritis and limited evidence on its relevance in practice do not advocate its use in daily routine.