MRI of the sacroiliac joints: what is and what is not sacroiliitis?

Pro-inflammatory cytokines in spondyloarthritis: a case-control study

OBJECTIVES

We aimed to determine the discriminative values of pro-inflammatory cytokines to distinguish spondyloarthritis patients from healthy subjects and to assess the association between these cytokines and spondyloarthritis characteristics.

METHODS

We conducted a case-control study, including 144 subjects matched for age and sex: 72 spondyloarthritis patients(G1) and 72 controls (G2). The disease activity was assessed using ASDAS-CRP and BASDAI. Structural damage was assessed using BASRI. The levels of interleukin (IL) IL-1, IL-6, IL-8, IL-17, IL-23, and tumor necrosis factor α(TNFα) were measured.

RESULTS

Each group included 57 men. The mean age was 44.84 ± 13.42 years. Except for IL-8, all cytokine levels were significantly higher in patients compared to controls (IL-1: p = 0.05, IL-6: p = 0.021, TNFα: p = 0.039, IL-17 and IL-23: p < 0.001). Cutoff values of IL-17 and IL-23 distinguishing patients in G1 from those in G2 were 17.6 and 7.96 pg/mL, respectively. TNFα level correlated to BASDAI (p = 0.029) and BASRI (p = 0.002). Multivariate analysis showed that structural damage was associated with the male gender (p = 0.017), longer disease duration (p = 0.038), and high disease activity (p = 0.044). Disease activity was associated with longer disease duration (p = 0.012) and increased IL-6 levels (p = 0.05).

CONCLUSION

Our study showed that IL-17 was the ablest to distinguish between spondyloarthritis patients and controls, suggesting that IL-17 may be helpful for the diagnosis of spondyloarthritis.

5. Sacroiliac joint pain

INTRODUCTION

Sacroiliac (SI) joint pain is defined as pain localized in the anatomical region of the SI joint. The reported prevalence of SI joint pain among patients with mechanical low back pain varies between 15% and 30%.

METHODS

In this narrative review, the literature on the diagnosis and treatment of SI joint pain was updated and summarized.

RESULTS

Patient's history provides clues on the source of pain. The specificity and sensitivity of provocative maneuvers are relatively high when three or more tests are positive, though recent studies have questioned the predictive value of single or even batteries of provocative tests. Medical imaging is indicated only to rule out red flags for potentially serious conditions. The diagnostic value of SI joint infiltration with local anesthetic remains controversial due to the potential for false-positive and false-negative results. Treatment of SI joint pain ideally consists of a multidisciplinary approach that includes conservative measures as first-line therapies (eg, pharmacological treatment, cognitive-behavioral therapy, manual medicine, exercise therapy and rehabilitation treatment, and if necessary, psychological support). Intra- and extra-articular corticosteroid injections have been documented to produce pain relief for over 3 months in some people. Radiofrequency ablation (RFA) of the L5 dorsal ramus and S1-3 (or 4) lateral branches has been shown to be efficacious in numerous studies, with extensive lesioning strategies (eg, cooled RFA) demonstrating the strongest evidence. The reported rate of complications for SI joint treatments is low.

CONCLUSIONS

SI joint pain should ideally be managed in a multidisciplinary and multimodal manner. When conservative treatment fails, corticosteroid injections and radiofrequency treatment can be considered.

Prevalence of axial spondyloarthritis in Colombia: data from the National Health Registry 2017-2021

INTRODUCTION

Registries allow ascertaining the epidemiology of chronic diseases such as axial spondyloarthritis (axSpA). The Colombian Ministry of Health has implemented a National Health Registry (SISPRO) that collects data from each medical contact in the system, which provides close to universal coverage (around 98%).

OBJECTIVE

To establish the 5-year prevalence of axSpA in Colombia, and to describe its demographics, using data from January 1st, 2017, to December 31st, 2021.

METHODS

We performed an observational, cross-sectional study using the International Statistical Classification of Diseases and Related Health Problems as search terms related to ax-SpA, based on SISPRO data. We estimated the prevalence using three approaches: (1) ankylosing spondylitis (AS) diagnoses; (2) diagnoses compatible with axSpA; and (3) diagnoses compatible with axSpA, including sacroiliitis. We calculated prevalence per 100,000 inhabitants.

RESULTS

Based on our three approaches, patients with a primary diagnosis compatible with ax-SpA ranged between 12,684 and 117,648, with an estimated 5-year adjusted prevalence between 26.3 and 244 cases per 100,000 inhabitants (0.03-0.2%). The male-to-female ratio ranged between 1.2:1 and 0.4:1, which was markedly skewed towards a higher prevalence in women when we included the code for sacroiliitis. We found the highest frequency of cases in the 50-54 years group. A differential prevalence was observed between different regions in our country, particularly in regions known to have European ancestors.

CONCLUSION

This is the first study that describes demographic characteristics of ax-SpA in Colombia and offers valuable information for stakeholders. Key Points • Using the official country-level health database, the prevalence of axSpA in Colombia ranges between 26.3 and 244 cases per 100,000 inhabitants (0.03% - 0.2%) • The prevalence of axSpA peaked among the 50-54 years patient group, suggesting an increased survival • Nations with a substantial admixture, such as Colombia, may present a differential prevalence of axSpA among regions within the country • Including the ICD-10 code for sacroiliitis (M46.1) in epidemiological studies probably overestimates the frequency of axSpA.

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.

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.

Zero Echo Time Musculoskeletal MRI: Technique, Optimization, Applications, and Pitfalls

Zero echo time (ZTE) imaging is an MRI technique that produces images similar to those obtained with radiography or CT. In ZTE MRI, the very short T2 signal from the mineralized trabecular bone matrix and especially cortical bone-both of which have a low proton density (PD)-is sampled in a unique sequence setup. Additionally, the PD weighting of the ZTE sequence results in less contrast between soft tissues. Therefore, along with gray-scale inversion from black to white and vice versa, ZTE imaging provides excellent contrast between cortical bone and soft tissues similar to that of radiography and CT. However, despite isotropic or near-isotropic three-dimensional (3D) imaging capabilities of the ZTE sequence, spatial resolution in this technique is still inferior to that of radiography and CT, and 3D volume renderings are currently time-consuming and require postprocessing software that features segmentation and manual contouring. Optimization of ZTE MRI mostly entails adjustments of bandwidth, flip angle, field of view, and image matrix. A wide range of structural abnormalities and disease or healing processes in the musculoskeletal system are well delineated with ZTE MRI, including conditions that involve bone-based morphometric analyses (which aid diagnosis, help prognostication, and guide surgery), impaction, avulsion and stress fractures, loose bodies or erosions in and around joints, soft-tissue calcifications and ossifications, and bone tumors (including treatment response). The pitfalls of ZTE imaging include mimics of foci of calcification or ossification such as intra-articular gas and susceptibility artifacts from surgical materials and hemosiderin deposition, which can be avoided in many instances by cross-referencing images obtained with other MRI sequences. Online supplemental material is available for this article. ^©RSNA, 2022.

Clinical characteristics, treatment and outcomes of acute postpartum inflammatory sacroiliitis: a retrospective study

PURPOSE

We performed this research to report the clinical characteristics and clinical therapeutic strategies of acute postpartum inflammatory sacroiliitis.

METHODS

We retrospectively analyzed the data of patients diagnosed with acute postpartum inflammatory sacroiliitis from 2014 to 2020. All their clinical details including clinical symptoms and signs, laboratory tests, radiologic examination, diagnosis and treatment process and clinical outcomes were obtained and analyzed in this retrospective analysis.

RESULTS

Eleven patients diagnosed with acute postpartum inflammatory sacroiliitis complain of low back pain. Magnetic resonance imaging (MRI) is useful in diagnosing acute postpartum inflammatory sacroiliitis. The systemic non-steroidal anti-inflammatory drugs (NSAIDs) administration, sacroiliac joint injection, and physical therapy effectively alleviated the pain with symptoms disappearing, and the abnormal signal reduced in MRI.

CONCLUSION

Acute postpartum inflammatory sacroiliitis is an uncommon disease with atypical symptoms. MRI examination may be the best diagnostic method. General NSAIDs and sacroiliac joint injections of local anesthetic plus corticosteroid under the guidance of fluoroscopy or ultrasound can achieve safe and effective treatment. This retrospective study was approved by the Committee on the Ethics of our hospital (No. 202101023).

TRIAL REGISTRY

Trial registration was performed in the Chinese Clinical Trial Registry ( http://www.chictr.org.cn , No. ChiCTR2100045656).

MRI in axial spondyloarthritis: understanding an 'ASAS-positive MRI' and the ASAS classification criteria

In 2009, the Assessment of SpondyloArthritis international Society (ASAS) published a definition of 'active sacroiliitis on magnetic resonance imaging (MRI) for classification of axial spondyloarthritis'. This new definition of an 'ASAS-positive MRI' was integral to new classification criteria for axial spondyloarthritis that were published in the same year. The ASAS MRI definition had the considerable advantage of simplicity and the definition gained popularity as guidance for interpreting MRI of the sacroiliac joints in clinical practice. However, classification criteria are not designed for use in clinical practice with the consequence that overreliance on the presence of bone marrow edema, which is the principal determinant of an 'ASAS-positive MRI', may result in a tendency to overcall inflammatory sacroiliitis in the clinical setting. This article aims to inform the reader about the rationale behind the ASAS definition of a positive MRI and ASAS classification criteria, their proper use in research and why they should not be used in clinical practice. The article also contains guidance for an updated imaging protocol and interpretation of images including typical imaging findings, differential diagnosis, and common pitfalls.

Diagnosing axial spondyloarthritis by multidiciplinary team conference at 3.5 years' follow-up in a cohort of patients with disease features according to the ASAS criteria

OBJECTIVES

During the past two decades, magnetic resonance imaging (MRI) has increasingly been used diagnostically in axial spondyloarthritis (axSpA), and in 2009 MRI was introduced in the Assessment of SpondyloArthritis Society (ASAS) classification criteria. In clinical practice, there is a risk of overdiagnosis if MRI findings are not related to clinical and biochemical findings. The aim of this study was to provide an estimate of the prevalence of axSpA in a cohort of clinical patients with low back pain and findings suggestive of axSpA according to ASAS through consensus diagnosis at a multi-disciplinary team (MDT) conference, and to describe the performance of the features included in the ASAS criteria.

METHOD

Consensus diagnoses of axSpA at MDT conferences were retrospectively established at 3.5 years' follow-up in a cohort of 84 patients, initially referred with disease features according to the ASAS criteria. Patients were examined clinically regarding spondyloarthritis features, and biochemical tests and MRI of the sacroiliac joints and entire spine were performed at baseline and after a mean of 3.5 years.

RESULTS

According to the MDT consensus, 25 patients (30%) of the total cohort had axSpA at follow-up; 40% of individuals who fulfilled the ASAS criteria at baseline had axSpA, and 37% at follow-up; 96% of axSpA patients according to the MDT consensus met the ASAS criteria at baseline and 92% at follow-up.

CONCLUSION

Approximately one-third of the included patients had axSpA when evaluated at the MDT conference. The ASAS criteria had low predictive value, but high sensitivity at both baseline and follow-up.

Anatomical Joint Form Variation in Sacroiliac Joint Disease: Current Concepts and New Perspectives

Purpose of Review

The aim of this article is to further the understanding of anatomical variation of the sacroiliac joint (SIJ) within the rheumatological community and point out promising fields of research in the interplay of SIJ anatomy and joint disease.

Recent Findings

Mechanical strain has long been implicated in onset and progression of axial spondyloarthritis (axSpA). Recent investigations found changes in the pattern of degenerative lesions of the SIJ in the normal population in patients with atypical joint forms. Furthermore, atypical SIJ forms are more prevalent in patients with axial spondyloarthritis and mechanical SIJ disease.

Summary

Mechanical stress from anatomical joint form variation may have an impact on development and progression of axSpA. Furthermore, mechanically induced bone marrow edema may act as an axSpA mimic on MRI and needs to be more accurately classified.