MRI predictors of infectious etiology in patients with unilateral sacroiliitis.

BACKGROUND: Unilateral presentation of sacroiliitis is a diagnostic dilemma, especially between infection and inflammatory sacroiliitis associated with spondyloarthritis, requiring an early and accurate diagnosis. OBJECTIVE: To assess the utility of magnetic resonance imaging (MRI) in differentiating infective versus inflammatory etiology in unilateral sacroiliitis. MATERIALS AND METHODS: Retrospective review of the MRI of 90 patients with unilateral sacroiliitis, having an established final diagnosis. MR images were evaluated for various bone and soft tissue changes using predefined criteria and analyzed using univariate and multivariate regression analysis. RESULTS: Among the 90 patients, infective etiology was diagnosed in 66 (73.3%) and inflammatory etiology in 24 (26.7%). Large erosions, both iliac and sacral-sided edema, joint space involvement with effusion or synovitis, soft tissue edema, elevated ESR/CRP, and absence of capsulitis and enthesitis were associated with infection (p < .001). The independently differentiating variables favoring infection on multivariate analysis were-both iliac and sacral-sided edema (OR 4.79, 95% CI: 0.96-23.81, p = .05), large erosions (OR 17.96, 95% CI: 2.66-121.02, p = .003), and joint space involvement (OR 9.9, 95% CI: 1.36-72.06, p = .02). Exclusive features of infection were osteomyelitis, sequestra, abscesses, sinus tracts, large erosions, and multifocality. All infective cases had soft tissue edema, joint space involvement, elevated ESR, and no capsulitis. CONCLUSION: MRI evaluation for the presence and pattern of bone and joint space involvement, soft tissue involvement, and careful attention to certain exclusive features will aid in differentiating infectious sacroiliitis from inflammatory sacroiliitis.

Case report: VEXAS syndrome: an atypical indolent presentation as sacroiliitis with molecular response to azacitidine.

VEXAS syndrome is a recently described autoinflammatory syndrome caused by the somatic acquisition of UBA1 mutations in myeloid precursors and is frequently associated with hematologic malignancies, chiefly myelodysplastic syndromes. Disease presentation can mimic several rheumatologic disorders, delaying the diagnosis. We describe a case of atypical presentation resembling late-onset axial spondylarthritis, later progressing to a systemic inflammatory syndrome with chondritis, cutaneous vasculitis, and transfusion-dependent anemia, requiring high doses of steroids. Ruxolitinib was used as the first steroid-sparing strategy without response. However, azacitidine showed activity in controlling both inflammation and the mutant clone. This case raises the question of whether azacitidine's anti-inflammatory effects are dependent on or independent of clonal control. We discuss the potential relevance of molecular remission in VEXAS syndrome and highlight the importance of a multidisciplinary team for the care of such complex patients.

Presentation of enthesitis-related arthritis and juvenile-onset spondyloarthritis: a cross-sectional study in a pediatric and adult clinic.

BACKGROUND: Juvenile idiopathic arthritis (JIA) comprises a whole spectrum of chronic arthritis starting before 16 years of age. The study aims to explore the clinical and demographic descriptors, treatment, and disease progression of enthesitis-related arthritis (ERA) in comparison with juvenile-onset spondyloarthritis (SpA). METHODS: Cross-sectional analysis of consecutive patients in two dedicated clinics, with a single visit and retrospective case-notes review. Arthritis, enthesitis and sacroiliitis were evaluated by scoring disease activity and damage. Continuous variables were reported by median, interquartile range; categorical variables were reported by the frequency comparison of the two groups. RESULTS: Thirty-three cases were included, being 23 (69.7%) with ERA. The median age at diagnosis was 12.5 y (SpA) vs. 9 y (ERA) (p < 0.01); the time from symptom onset to diagnosis was 5.5 y (SpA) vs. 1.5 y (ERA) (p < 0.03). In both groups, the predominant presentation was a single joint or < 5 lower limb joints and asymmetric involvement, with a high frequency of enthesitis. There was a higher frequency of mid-tarsal and ankle synovitis in the ERA group and hip involvement in those with SpA. The comparison of the frequency of spine symptoms at presentation, 30% SpA vs. 21.7% ERA (p = 0.7), was not significant, and radiographic progression to spinal involvement occurred in 43.5% of ERA patients. The median time for spinal progression and age at onset was 2.2 and 12 y for ERA, and 4 and 16.5 y for SpA, respectively. Activity and damage scores were not significantly different between the groups. Treatment comparison resulted in 91.3% of ERA and 100% SpA being treated, predominantly with NSAIDs in both groups, followed by DMARDs and biologics, with a higher frequency of biologics in SpA. CONCLUSION: The main differences were the late diagnoses of SpA, and the hip and spine involvement, with higher frequency of biologic treatment in juvenile-onset SpA compared to ERA.

Effective diagnosis of sacroiliitis in children: evaluating magnetic resonance imaging with the Canadian scoring system.

OBJECTIVES: To reveal the differences by comparing the magnetic resonance imaging (MRI) findings of patients with clinically symptomatic sacroiliitis with those undergoing sacroiliac imaging for other reasons using the Canadian Spondyloarthritis Research Consortium-Sacroiliac Inflammatory Scoring System (SPARCC-SIS). METHODS: In this retrospective single-center study, sacroiliac MRIs performed between 2017 and 2023 were evaluated from the database. The SPARCC-SIS scoring system is used to evaluate and grade the inflammation of the sacroiliac joints. Mild inflammation is indicated by a score below 24, moderate by a score of 24-48, and severe by a score above 49. Additionally, structural defects of the sacroiliac joint, such as erosion, sclerosis, and ankylosis, were observed. After MRI evaluation, clinically symptomatic (group 1) and non-symptomatic (group 2) patients were divided into two groups. The clinical and laboratory findings of the patients and MRI findings were compared. The patient's age, gender, clinical information from hospital records, acute phase reactants (APRs), and the presence of the Human Leukocyte Antigen (HLA-B27) gene (if applicable) were thoroughly recorded. RESULTS: One hundred thirty-six children who performed sacroiliac MRI for any indication were included in the study. The APRs positivity, presence of HLA-B27, and SPARCC scoring system were significantly higher in 24 patients with clinical sacroiliitis (group 1) than in 112 patients without sacroiliitis (group 2). In our study, the most common MRI findings in children were bone marrow edema, capsulitis, synovitis, and erosion, while chronic structural changes such as sclerosis and ankylosing were rare. CONCLUSION: In this study, the SPARCC scoring method, which shows the severity of sacroiliac joint inflammation, correlates with the clinical diagnosis of sacroiliitis. In cases with suspected sacroiliitis, except for extraordinary reasons, it can be evaluated with MRI without contrast material and can be graded to guide the clinician in treatment and approach.

Relationship between sacroiliitis and inflammatory markers in familial Mediterranean fever.

OBJECTIVE: Familial Mediterranean fever is the most common monogenic autoinflammatory disease. This study aimed to evaluate the relationship between sacroiliitis observed in familial Mediterranean fever and hematological inflammatory markers. METHODS: In this study, 168 familial Mediterranean fever patients were examined. A total of 61 familial Mediterranean fever patients who had sacroiliac magnetic resonance imaging due to waist and hip pain were included in the study. According to the magnetic resonance imaging findings, patients were divided into two groups: with and without sacroiliitis. The relationship between hematological inflammatory markers and sacroiliitis was investigated. RESULTS: The frequency of sacroiliitis was found to be 13.6% in all familial Mediterranean fever patients and 37.8% in patients with low back pain who underwent sacroiliac magnetic resonance imaging. Neutrophil count, neutrophil/lymphocyte ratio, monocyte/lymphocyte ratio, and systemic immune-inflammatory index were significantly higher in the sacroiliitis group than in the other group, and this difference was found to be statistically significant (p<0.05). As a result of the receiver operating characteristic analysis, it was observed that neutrophil/lymphocyte ratio, monocyte/lymphocyte ratio, and systemic immune-inflammatory index were very sensitive parameters in determining sacroiliitis in patients with familial Mediterranean fever. CONCLUSION: It was observed that the frequency of sacroiliitis was increased in familial Mediterranean fever patients. It is predicted that hematological inflammatory markers such as neutrophil/lymphocyte ratio, monocyte/lymphocyte ratio, and systemic immune-inflammatory index can be used in the diagnosis of sacroiliitis.

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.

Sacroiliitis in inflammatory bowel disease.

PURPOSE OF REVIEW: This review summarizes the recent evidence regarding the epidemiology of inflammatory bowel disease (IBD) associated sacroiliitis, including the prevalence, pathogenesis, role of imaging, and therapeutic challenges. RECENT FINDINGS: Sacroiliitis is an underappreciated musculoskeletal manifestation of IBD, a chronic inflammatory condition of the gut affecting the younger population. Untreated sacroiliitis can lead to joint destruction and chronic pain, further adding to morbidity in IBD patients. Recent publications suggest sacroiliitis can be detected on abdominal imaging obtained in IBD patients to study bowel disease, but only a small fraction of these patients were seen by rheumatologists. Early detection of IBD-associated sacroiliitis could be achieved by utilization of clinical screening tools in IBD clinics, careful examination of existing computed tomography and MRI studies, and timely referral to rheumatologist for further evaluation and treatment. Current treatment approaches for IBD and sacroiliitis include several targeted biologic therapies, but IBD-associated sacroiliitis has limited options, as these therapies may not overlap in both conditions. SUMMARY: With the advances in imaging, sacroiliitis is an increasingly recognized comorbidity in IBD patients. Future studies focusing on this unique patient population will expand our understanding of complex pathophysiology of IBD-associated sacroiliitis and lead to identification of novel targeted therapies for this condition.

Does sacroiliitis is a mandatory criterion for enthesitis-related arthritis diagnosis?

INTRODUCTION AND OBJECTIVES: Magnetic resonance imaging (MRI) sensitivity and specificity seem to be less studied in enthesitis-related arthritis (ERA). We aimed to determine the ability of sacroiliac MRI to diagnose ERA patients. MATERIALS AND METHODS: We conducted a retrospective study including 44 patients with juvenile idiopathic arthritis (JIA). Each patient had a sacroiliac joint MRI. We divided patients into two groups: G1 patients with ERA and G2 patients with non-ERA subtype. RESULTS: ERA was noted in 61% of the cases. Sacroiliac joints were painful in 15 patients (34%). MRI was normal in 25 patients (57%) (G1:11 versus G2:14) and showed bone marrow edema in the sacroiliac joints in 19 patients (34%) (G1=16 versus G2=3, p=0.005). Sacroiliac joints MRI's sensitivity and specificity in the ERA diagnosis were 61.54% and 82.35%, respectively. Positive and negative predictive values were 84.21% and 58.33%, respectively. Furthermore, sacroiliac joint pain in the clinical examination was able to predict sacroiliac bone edema in MRI with an odds ratio of 6.8 (95% CI 1.68-28.09; p=0.006). CONCLUSION: Our study showed that sacroiliac joint MRI has good specificity and positive predictive value in the diagnosis of ERA patients among JIA patients. This underlines the usefulness of sacroiliac joint MRI in the early diagnosis of ERA patients.

A rare case presentation of septic sacroiliitis caused by staphylococcus xylosus and complicated with abscess formation: A case report.

Septic sacroiliitis is one of the infectious causes of sacroiliitis and it is seen rarely. In current literature, cases of septic sacroiliitis caused by several microorganisms have been reported so far. This case report presents the first case of septic sacroiliitis caused by Staphylococcus xylosus and also complicated with an abscess formation.

[Septic sacroiliitis: early diagnosis due to specific physical examination]. / Septische sacroiliitis.

BACKGROUND: Septic sacroiliitis is an uncommon disease which represents approximately 1-4% of all joint infections, therefore it is difficult to make the right diagnosis and to start early treatment. CASE REPORT: A 18 year old woman was admitted to the emergency room with a fever and pain in the left gluteal region. The patient was considered healthy and had no risk factors for septic arthritis. Edema and a small abscess was found in and around the left sacroiliac joint on pelvic MRI. The patient had positive blood cultures with Staphylococcus Aureus. Antibiotic treatment was initiated and lasted 7 weeks. She recovered completely and had no remaining complaints. CONCLUSION: Physical exam and clinical suspicion are important to consider the diagnosis of septic sacroiliitis. In addition a MRI of the pelvic is the best radiographic exam to conform the diagnosis.

Does sacroiliitis is a mandatory criterion for enthesitis-related arthritis diagnosis? / ¿La sacroilitis es un criterio obligatorio para el diagnóstico de artritis relacionada con entesitis?

Introduction and objectives: Magnetic resonance imaging (MRI) sensitivity and specificity seem to be less studied in enthesitis-related arthritis (ERA). We aimed to determine the ability of sacroiliac MRI to diagnose ERA patients. Materials and methods: We conducted a retrospective study including 44 patients with juvenile idiopathic arthritis (JIA). Each patient had a sacroiliac joint MRI. We divided patients into two groups: G1 patients with ERA and G2 patients with non-ERA subtype. Results: ERA was noted in 61% of the cases. Sacroiliac joints were painful in 15 patients (34%). MRI was normal in 25 patients (57%) (G1:11 versus G2:14) and showed bone marrow edema in the sacroiliac joints in 19 patients (34%) (G1=16 versus G2=3, p=0.005). Sacroiliac joints MRI's sensitivity and specificity in the ERA diagnosis were 61.54% and 82.35%, respectively. Positive and negative predictive values were 84.21% and 58.33%, respectively. Furthermore, sacroiliac joint pain in the clinical examination was able to predict sacroiliac bone edema in MRI with an odds ratio of 6.8 (95% CI 1.68–28.09; p=0.006). Conclusion: Our study showed that sacroiliac joint MRI has good specificity and positive predictive value in the diagnosis of ERA patients among JIA patients. This underlines the usefulness of sacroiliac joint MRI in the early diagnosis of ERA patients.(AU)

Introducción y objetivos: La sensibilidad y especificidad de la resonancia magnética parecen estar menos estudiadas en la artritis relacionada con entesitis (ERA). Nuestro objetivo era determinar la capacidad de la resonancia magnética de la articulación sacroilíaca para diagnosticar pacientes con ERA. Materiales y métodos: Realizamos un estudio retrospectivo que incluyó a 44 pacientes con artritis idiopática juvenil (AIJ). A cada paciente se le realizó una resonancia magnética de la articulación sacroilíaca. Dividimos a los pacientes en dos grupos: G1: pacientes con ERA y G2: pacientes con subtipo no ERA. Resultados: Se observó ERA en 61% de los casos. Las articulaciones sacroilíacas resultaron dolorosas en 15 pacientes (34%). La resonancia magnética fue normal en 25 pacientes (57%) (G1:11 vs. G2:14) y mostró edema de médula ósea en las articulaciones sacroilíacas en 19 pacientes (34%) (G1=16 vs. G2=3, p=0,005). La sensibilidad y especificidad de la resonancia magnética de articulaciones sacroilíacas en el diagnóstico de ERA fueron de 61,54 y 82,35%, respectivamente. Los valores predictivos positivos y negativos fueron 84,21 y 58,33%, respectivamente. Además, el dolor en la articulación sacroilíaca en el examen clínico fue capaz de predecir el edema del hueso sacroilíaco en la resonancia magnética con un odds ratio de 6,8 (IC 95%: 1,68 a 28,09; p=0,006). Conclusión: Nuestro estudio demostró que la resonancia magnética de la articulación sacroilíaca tiene buena especificidad y valor predictivo positivo en el diagnóstico de pacientes con ERA entre pacientes con AIJ. Esto subraya la utilidad de la resonancia magnética de la articulación sacroilíaca en el diagnóstico temprano de pacientes con ERA.(AU)

Sacroiliitis in inflammatory bowel disease on abdominal computed tomography: prevalence, misses, and associated factors.

OBJECTIVE: To evaluate the prevalence and rate of a missed diagnosis of sacroiliitis on abdominal computed tomography (CT) in patients with inflammatory bowel disease (IBD). Factors associated with sacroiliitis were also assessed. METHOD: This retrospective study included 210 patients with IBD (mean age 31.1 years) who underwent abdominal CT. Based on a validated abdominal CT scoring tool, bilateral sacroiliac (SI) joints on abdominal CT in the whole study population were retrospectively reviewed. Subsequently, patients were classified into the 'patients with sacroiliitis' group and the 'patients without sacroiliitis' group. Univariate and multivariate regression analyses were used to clarify the factors associated with sacroiliitis. RESULTS: Sacroiliitis was identified in 26 out of 210 patients (12.4%). However, sacroiliitis was recognized on the primary reading in only five of these 26 patients (19.2%) and was missed on the initial report in the remaining 21 patients (80.8%). Among the 21 patients, 20 (95.2%) were finally diagnosed with axial spondyloarthritis (axSpA). There was a higher prevalence of female sex (p = 0.04), upper gastrointestinal involvement (p = 0.04), and back pain (p < 0.01) in patients with sacroiliitis than in those without sacroiliitis. However, on multivariate analysis, back pain was the only factor associated with sacroiliitis (p = 0.01). CONCLUSION: Physicians should carefully evaluate SI joints on abdominal CT in patients with IBD to enable early detection of sacroiliitis, potentially leading to an early diagnosis of axSpA. In addition, if patients with IBD present with back pain, the possibility of sacroiliitis should be considered.

How to inject sacroiliac joints with ultrasound guidance: a pictorial essay.

Active sacroiliitis and sacroiliac joint dysfunction represent a common cause of low back pain in the population and are cause of patients' quality of life reduction and disability worldwide. The use of musculoskeletal ultrasound allows to easily identify the sacroiliac joints and to study every pathological condition affecting its most dorsal part; moreover, musculoskeletal ultrasound allows to guide highly effective injective procedures aimed at improving patients' symptoms and enhance their well-being. This paper aims to briefly explain for the musculoskeletal sonographer the anatomy and biomechanics of the sacroiliac joints, the correct ultrasound scanning method for their visualization and the most appropriate ultrasound guided injection technique to help dealing with the diagnostic and management of sacroiliac joint pain in the everyday scenario.

The bright Easter bunny sign: a useful aide-memoire on MRI for costotransverse joint inflammation in axial spondyloarthritis.

AIM: To assess the significance of the "bright Easter bunny" sign on magnetic resonance imaging (MRI) to indicate inflammatory costotransverse joint (CtJ) lesions to diagnose axial spondyloarthritis (ax-SpA). MATERIALS AND METHODS: Consecutive cases of patients with ax-SpA from a specialist rheumatology clinic were analysed retrospectively over two cohorts, between 2012-2014 and 2018-2020, to determine newly diagnosed patients under the Assessment of SpondyloArthritis international Society (ASAS) criteria. Biological naive adult patients who underwent spine MRI and sacroiliac imaging with full immunological work-up and a C-reactive protein reading within 3 months of the scan were included. Blinded images were reviewed by experienced musculoskeletal radiologists. RESULT: From the 1,284 cases that were identified, 40 cases met the inclusion criteria for this study. Seven out of the 40 cases (17.5%) identified inflammatory lesions at the CtJ with five (70%) showing concordance with the bright Easter bunny sign. CONCLUSION: The bright Easter bunny sign is concordant with inflammatory costotransverse enthesitis. This aide-memoire radiological sign is often on overlooked edge-of-field sections and this emphasises the need to ensure adequate coverage of the CtJ on spine MRI protocols as an important anatomical site of inflammatory change in ax-SpA assessment.

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.

MRI for axial SpA: Diagnosis, disease activity assessment, and recent advances.

Magnetic resonance imaging (MRI) is a sensitive imaging modality to detect early inflammatory changes in axial spondyloarthritis (SpA). Over a decade has passed since the inclusion of MRI assessment in the 2009 Assessment of SpondyloArthritis International Society (ASAS) classification criteria for axial SpA. Evidence and clinical experience of MRI in axial SpA have accumulated rapidly since. This has led to a better understanding of the clinical utility of MRI in early diagnosis, disease activity assessment, and monitoring of treatment response in axial SpA. Furthermore, technological advancements have paved the way for the development of novel MRI sequences for the quantification of inflammation and image optimization. The field of artificial intelligence has also been explored to aid medical imaging interpretation, including MRI in axial SpA. This review serves to provide an update on the latest understanding of the evolving roles of MRI in axial SpA.

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.

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.