Spondyloarthritis Research Consortium of Canada Scoring System for Sacroiliitis in Juvenile Spondyloarthritis/Enthesitis-related Arthritis: A Reliability, Validity, and Responsiveness Study

Characterization of bone marrow lesions in axial spondyloarthritis using quantitative T1 mapping MRI

OBJECTIVE

Conventional magnetic resonance imaging (MRI) uses T1-weighted and short-tau inversion recovery (STIR) sequences to characterize bone marrow in axial spondyloarthritis. However, quantification is restricted to estimating the extent of lesions because signal intensities are highly variable both within individuals and across patients and MRI scanners. This study evaluates the performance of quantitative T1 mapping for distinguishing different types of bone marrow lesions of the sacroiliac joints.

MATERIALS AND METHODS

In this prospective study, 62 patients underwent computed tomography (CT) and MRI of the sacroiliac joints including T1, STIR, and T1 mapping. Bone marrow lesions were characterized by three readers and assigned to one of four groups: sclerosis, osteitis, fat lesions, and mixed marrow lesions. Relaxation times on T1 maps were compared using generalized estimating equations and receiver operating characteristics (ROC) analysis.

RESULTS

A total of 119 lesions were selected (sclerosis: 38, osteitis: 27, fat lesions: 40; mixed lesions: 14). T1 maps showed highly significant differences between the lesions with the lowest values for sclerosis (1516±220 ms), followed by osteitis (1909±75 ms), and fat lesions (2391±200 ms); p<0.001. T1 mapping differentiated lesions with areas under the ROC curve of 99% (sclerosis vs. osteitis) and 100% (other comparisons).

CONCLUSION

T1 mapping allows accurate characterization of sclerosis, osteitis, and fat lesions at the sacroiliac joint but only for homogeneous, non-mixed lesions. Thus, further sequence development is needed before implementation in clinical routine.

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.

The Efficacy and Safety of Subcutaneous Ixekizumab for the Treatment of Axial Spondylarthritis: A Systematic Review and Meta-Analysis

Axial spondylarthritis (axSpA) is a progressive inflammatory condition that is treated with various management options. Interleukin-17A (IL-17A) inhibitors are a novel therapeutic option that demonstrates both efficacy and safety. This systematic review and meta-analysis evaluated the effectiveness of ixekizumab and its safety compared to a placebo. Medline, ScienceDirect, EBSCO, and Cochrane Central Register of Controlled Trials (CENTRAL) were searched. We included randomized control trials (RCTs) that assessed the efficacy and safety of ixekizumab versus the placebo. The GRADE (Grading of Recommendations, Assessment, Development, and Evaluations) assessment was utilized to evaluate the certainty of evidence. The revised Cochrane risk of bias tool for randomized trials was used to assess the risk of bias. Four RCTs (n=1016) met the eligibility criteria. All included studies had a low risk of bias. Significant improvements in the Assessment of Spondylarthritis International Society response for 40% improvement (ASAS40) (RR = 2.39, 95% CI 1.72-3.31, P < 0.01, I2 = 23%), Ankylosing Spondylitis Disease Activity Score (ASDAS) (SMD= -9.28 95% CI -12.31- (-6.25), P < 0.01, I2=97%), and Spondylarthritis Research Consortium of Canada (SPRACC score) (SMD= -5.82 95% CI -7.16- (-4.47), P < 0.01, I2=94%) were noted in comparison to placebo. Regarding safety, there was an insignificant increase in risk for serious adverse events (SAEs) (RR = 1.19, 95% CI 0.45-3.14, P = 0.73, I2 = 0%). Additionally, significant nonserious adverse events (NSAEs) (RR = 1.54, 95% CI 1.19-1.99, P = 0.001, I2 = 0%) were noted for the ixekizumab arm. No mortality events were detected in both arms. Ixekizumab, which demonstrates significant improvement in all efficacy endpoints, is a promising management option for axSpA patients who fail non-steroidal anti-inflammatory drugs (NSAIDs) therapy. However, the significant risk of developing adverse events hinders its utilization. More high-quality RCTs with larger sample sizes and prolonged follow-up periods are warranted to further assess this treatment option.

The role of whole-body MRI in musculoskeletal inflammation detection and treatment response evaluation in inflammatory arthritis across age: A systematic review

OBJECTIVE

To evaluate the relation between whole-body MRI (WBMRI) outcomes and disease activity measures, including clinical examination, composite scores, and other imaging outcomes, and the ability of WBMRI to detect treatment response in patients with inflammatory arthritis (IA) across age.

METHODS

Human studies published as full text or abstract in the PubMed and MEDLINE and Cochrane databases from inception to 11th April 2021 were systematically and independently searched by two reviewers. Studies including patients with rheumatoid arthritis (RA), psoriatic arthritis (PsA), spondyloarthritis (SpA), juvenile idiopathic arthritis (JIA) or unclassified inflammatory arthritis (UA) who underwent WBMRI and which reported on disease outcomes were included.

RESULTS

Nineteen full-text studies were eligible for inclusion: 2 interventional, 7 retrospective and 10 prospective observational studies, comprising 540 participants (SpA 38.7%, RA 24.8%, JIA 17.8%, PsA 11.5%, healthy controls 5.9%, UA 1.3%). Abstracts of 6 conference papers were reported separately. Five studies in PsA and SpA and 4 in RA measured the frequency of WBMRI-detected and clinically-detected synovitis, and all found the former to be more frequent. Less enthesitis was detected by WBMRI than clinical examination in 5/8 studies. After biologic treatment, the WBMRI inflammation scores declined in 3 studies in SpA and 2 in RA, whilst in 3 studies the results were equivocal.

CONCLUSION

The ability of WBMRI to assess disease activity and treatment response in IA was adequate overall. Further studies are needed to corroborate WBMRI findings with IA outcomes and investigate the clinical value of subclinical inflammation.

Automated segmentation of magnetic resonance bone marrow signal: a feasibility study

BACKGROUND

Manual assessment of bone marrow signal is time-consuming and requires meticulous standardisation to secure adequate precision of findings.

OBJECTIVE

We examined the feasibility of using deep learning for automated segmentation of bone marrow signal in children and adolescents.

MATERIALS AND METHODS

We selected knee images from 95 whole-body MRI examinations of healthy individuals and of children with chronic non-bacterial osteomyelitis, ages 6-18 years, in a longitudinal prospective multi-centre study cohort. Bone marrow signal on T2-weighted Dixon water-only images was divided into three color-coded intensity-levels: 1 = slightly increased; 2 = mildly increased; 3 = moderately to highly increased, up to fluid-like signal. We trained a convolutional neural network on 85 examinations to perform bone marrow segmentation. Four readers manually segmented a test set of 10 examinations and calculated ground truth using simultaneous truth and performance level estimation (STAPLE). We evaluated model and rater performance through Dice similarity coefficient and in consensus.

RESULTS

Consensus score of model performance showed acceptable results for all but one examination. Model performance and reader agreement had highest scores for level-1 signal (median Dice 0.68) and lowest scores for level-3 signal (median Dice 0.40), particularly in examinations where this signal was sparse.

CONCLUSION

It is feasible to develop a deep-learning-based model for automated segmentation of bone marrow signal in children and adolescents. Our model performed poorest for the highest signal intensity in examinations where this signal was sparse. Further improvement requires training on larger and more balanced datasets and validation against ground truth, which should be established by radiologists from several institutions in consensus.

Recent Updates in Juvenile Spondyloarthritis

Spondyloarthritis represents a group of disorders characterized by enthesitis and axial skeletal involvement. Juvenile spondyloarthritis begins before age 16. Joint involvement is usually asymmetric. Bone marrow edema on noncontrast MRI of the sacroiliac joints can facilitate diagnosis. The most significant risk factor for axial disease is HLA-B27. Most patients have active disease into adulthood. Enthesitis and sacroiliitis correlate with greater pain intensity and poor quality-of-life measures. Tumor necrosis factor inhibitors are the mainstay of biologic therapy. Although other biologics such as IL-17 blockers have shown benefit in adult spondyloarthritis, none are approved by the US Food and Drug Administration.

Reliability of the Preliminary OMERACT Juvenile Idiopathic Arthritis MRI Score (OMERACT JAMRIS-SIJ)

This study reports the reliability of the juvenile idiopathic arthritis magnetic resonance imaging scoring system (JAMRIS-SIJ). The study comprised of eight raters—two rheumatologists and six radiologists—and 30 coronal T1 and Short-Tau Inversion Recovery (STIR) MRI scans of patients with enthesitis-related juvenile spondylarthritis. The median age of patients was 15 years with a mean disease duration of 5 years and 22 (73.3%) of the sample were boys. The inter-rater agreement of scores for each of the JAMRIS-SIJ items was calculated using a two-way random effect, absolute agreement, and single rater intraclass correlation coefficient (ICC 2.1). The ICC was interpreted together with kurtosis, since the ICC is also affected by the distribution of scores in the sample. The eight-rater, single measure inter-rater ICC (and kurtosis) values for JAMRIS-SIJ inflammation and damage components were the following: bone marrow edema (BME), 0.76 (1.2); joint space inflammation, 0.60 (1.8); capsulitis, 0.58 (9.2); enthesitis, 0.20 (0.1); ankylosis, 0.89 (35); sclerosis, 0.53 (4.6); erosion, 0.50 (6.5); fat lesion, 0.40 (21); backfill, 0.38 (38). The inter-rater reliability for BME and ankylosis scores was good and met the a priori set ICC threshold, whereas for the other items it was variable and below the selected threshold. Future directives should focus on refinement of the scores, definitions, and methods of interpretation prior to validation of the JAMRIS-SIJ through the assessment of its measurement properties.

Advances in Juvenile Spondyloarthritis

PURPOSE

To provide an overview of recent studies on pathogenesis, diagnosis, and management of juvenile spondyloarthritis (JSpA).

RECENT FINDINGS

Recent studies show differences in gut microbiome in patients with JSpA in comparison to healthy controls. There is increased recognition of the impact of the innate immune system on disease pathology. Normative reference on MRI of sacroiliac (SI) joints in children is now available. However, there is significant variability in interpretation of MRI of SI joints in children and a need for standardization. NSAIDs, physical therapy, and Tumor Necrosis Factor Inhibitors (TNFi) remain the mainstay of management for patients with JIA who have polyarthritis, sacroiliitis, and/or enthesitis as per recent ACR guidelines. Newer therapeutic options beyond TNFi are needed to manage patients who fail TNFi. This review highlights some of the recent advances in our knowledge of JSpA pathophysiology, diagnosis, and treatment. It also identifies areas in need of further research and standardization to improve our understanding and outcomes in JSpA.

Atlas of MRI findings of sacroiliitis in pediatric sacroiliac joints to accompany the updated preliminary OMERACT pediatric JAMRIS (Juvenile Idiopathic Arthritis MRI Score) scoring system: Part II: Structural damage lesions

Magnetic resonance imaging (MRI) is the imaging modality of choice for identifying sacroiliitis in juvenile idiopathic arthritis (JIA). Besides active lesions of sacroiliitis, of which bone marrow edema (BME) is the key feature, structural damage lesions can also be detected. Structural changes include erosion, sclerosis, fat lesion, backfill and ankylosis, and are more common at later stages. Systematic MRI assessment of inflammation and structural damage may aid in monitoring the course of the disease and evaluating treatment options. In this pictorial essay, we illustrate normal MRI findings and growth-related changes of the SIJ in the pediatric population, as well as the different MRI features of structural damage of sacroiliitis. This atlas can serve as a reference for assessing structural lesions of SIJ arthritis according to the updated preliminary JAMRIS (Juvenile Idiopathic Arthritis MRI Score) scoring system proposed by the MRI in JIA working group of Outcome Measures in Rheumatology and Clinical Trials (OMERACT). The atlas is intended to be read in conjunction with its companion Part 1, Active Lesions.

Atlas of MRI findings of sacroiliitis in pediatric sacroiliac joints to accompany the updated preliminary OMERACT pediatric JAMRIS (Juvenile Idiopathic Arthritis MRI Score) scoring system: Part I: Active lesions

Magnetic resonance imaging (MRI) is an increasingly important tool for identifying involvement of the sacroiliac joints (SIJ) in juvenile idiopathic arthritis (JIA). The key feature for diagnosing active sacroiliitis is bone marrow edema (BME), but other features of active arthritis such as joint space inflammation, inflammation in an erosion cavity, capsulitis and enthesitis can be seen as well. Structural changes may also be seen. Systematic MRI assessment of inflammation and structural damage may aid in monitoring the disease course, choice of therapeutics and evaluating treatment response. In this pictorial essay, we illustrate normal MRI findings and growth-related changes of the SIJ in the pediatric population, as well as the different MRI features of SIJ inflammation. This atlas demonstrates fundamental MRI disease features of active inflammation in a format that can serve as a reference for assessing SIJ arthritis according to the updated preliminary JAMRIS (Juvenile Idiopathic Arthritis MRI Score) scoring system proposed by the MRI in JIA working group of Outcome Measures in Rheumatology and Clinical Trials (OMERACT). The atlas is intended to be read in conjunction with its companion Part 2, Structural Lesions.

Biomarkers of Response to Biologic Therapy in Juvenile Idiopathic Arthritis

Background: Juvenile idiopathic arthritis (JIA) is the most common chronic inflammatory arthritis of childhood, characterized by various clinical phenotypes associated with variable prognosis. Significant progress has been achieved with the use of biologic treatments, which specifically block pro-inflammatory molecules involved in the disease pathogenesis. The most commonly used biologics in JIA are monoclonal antibodies and recombinant proteins targeting interleukins 1 (IL-1) and 6 (IL-6), and tumor necrosis factor α (TNF-α). Several biomarkers have been investigated in JIA. Aims: To assess the level of evidence available regarding the role of biomarkers in JIA related to guiding clinical and therapeutic decisions, providing disease prognostic information, facilitating disease activity monitoring and assessing biologic treatment response in JIA, as well as propose new strategies for biologic therapy-related biomarker use in JIA. Methods: We searched PubMed for relevant literature using predefined key words corresponding to several categories of biomarkers to assess their role in predicting and assessing biologic treatment response and clinical remission in JIA. Results: We reviewed serological, cellular, genetic, transcriptomic and imaging biomarkers, to identify candidates that are both well-established and widely used, as well as newly investigated in JIA on biologic therapy. We evaluated their role in management of JIA as well as identified the unmet needs for new biomarker discovery and better clinical applications. Conclusion: Although there are no ideal biomarkers in JIA, we identified serological biomarkers with potential clinical utility. We propose strategies of combining biomarkers of response to biologics in JIA, as well as routine implementation of clinically acceptable imaging biomarkers for improved disease assessment performance.

Current status of MR imaging of juvenile idiopathic arthritis

Juvenile idiopathic arthritis (JIA) is the most common chronic arthropathy in the pediatric population. Although the diagnosis is essentially clinical for many affected joints, MR imaging has become an important tool for the assessment of joints that are difficult to evaluate clinically, such as temporomandibular and sacroiliac joints, and for screening of inflammatory changes in the entire body by whole body MRI (WBMRI) assessment. The utilization of MR imaging is challenging in the pediatric population given the need for discrimination between pathological and physiological changes in the growing skeleton. Several multicentric multidisciplinary organizations have made major efforts over the past decades to standardize, quantify, and validate scoring systems to measure joint changes both cross-sectionally and longitudinally according to rigorous methodological standards. In this paper, we (1) discuss current trends for the diagnosis and management of JIA, (2) review challenges for detecting real pathological changes in growing joints, (3) summarize the current status of standardization of MRI protocols for data acquisition and the quantification of joint pathology in JIA by means of scoring systems, and (4) outline novel MR imaging techniques for the evaluation of anatomy and function of joints in JIA. Optimizing the role of MRI as a robust biomarker and outcome measure remains a priority of future research in this field.

Imaging assessment of children presenting with suspected or known juvenile idiopathic arthritis: ESSR-ESPR points to consider

Juvenile idiopathic arthritis (JIA) is the most common paediatric rheumatic disease. It represents a group of heterogenous inflammatory disorders with unknown origin and is a diagnosis of exclusion in which imaging plays an important role. JIA is defined as arthritis of one or more joints that begins before the age of 16 years, persists for more than 6 weeks and is of unknown aetiology and pathophysiology. The clinical goal is early suppression of inflammation to prevent irreversible joint damage which has shifted the emphasis from detecting established joint damage to proactively detecting inflammatory change. This drives the need for imaging techniques that are more sensitive than conventional radiography in the evaluation of inflammatory processes as well as early osteochondral change. Physical examination has limited reliability, even if performed by an experienced clinician, emphasising the importance of imaging to aid in clinical decision-making. On behalf of the European Society of Musculoskeletal Radiology (ESSR) arthritis subcommittee and the European Society of Paediatric Radiology (ESPR) musculoskeletal imaging taskforce, based on literature review and/or expert opinion, we discuss paediatric-specific imaging characteristics of the most commonly involved, in literature best documented and clinically important joints in JIA, namely the temporomandibular joints (TMJs), spine, sacroiliac (SI) joints, wrists, hips and knees, followed by a clinically applicable point to consider for each joint. We will also touch upon controversies in the current literature that remain to be resolved with ongoing research. KEY POINTS: • Juvenile idiopathic arthritis (JIA) is the most common chronic paediatric rheumatic disease and, in JIA imaging, is increasingly important to aid in clinical decision-making. • Conventional radiographs have a lower sensitivity and specificity for detection of disease activity and early destructive change, as compared to MRI or ultrasound. Nonetheless, radiography remains important, particularly in narrowing the differential diagnosis and evaluating growth disturbances. • Mainly in peripheral joints, ultrasound can be helpful for assessment of inflammation and guiding joint injections. In JIA, MRI is the most validated technique. MRI should be considered as the modality of choice to assess the axial skeleton or where the clinical presentation overlaps with JIA.

Whole-body MRI Quantification for Assessment of Bone Lesions in Chronic Nonbacterial Osteomyelitis Patients Treated With Pamidronate: A Prevalence, Reproducibility, and Responsiveness Study

OBJECTIVE

The purpose of this study was (1) to assess the interreader reliability in detecting and scoring the inflammatory bone lesions in pediatric patients with chronic nonbacterial osteomyelitis (CNO) by using whole-body magnetic resonance imaging (WB-MRI), and (2) to evaluate the responsiveness of the MRI-detected CNO lesions to pamidronate therapy.

METHODS

Eighty-eight WB-MRI examinations were independently reviewed and scored by 2 radiologists blinded to clinical details in 32 retrospectively enrolled pediatric patients with CNO. Inflammatory bone lesions, soft tissue abnormality, and bony structural changes were scored before and after pamidronate therapy. Lesion responsiveness was calculated by using standardized response mean and interreader reliability was assessed by k statistics.

RESULTS

There was good to excellent interreader agreement for the detection and quantification of bone lesions. After the first cycle of pamidronate in all 32 patients, 96 of the 279 lesions (34%; after excluding 108 lesions of hand and feet) resolved, whereas in a subset of 11 patients with 2 or more cycles, 76% of lesions resolved after the second cycle. Twenty-one (7.5%) lesions worsened and 46 (16.4%) new lesions developed after 1 cycle in all 32 patients. In these 11 patients, the number of worsened lesions reduced to 2 (2%) and new lesions to 14 (14.9%) after the second cycle as detected on MRI. Vertebral lesions had the highest response to treatment.

CONCLUSION

WB-MRI is a reliable tool for objective quantification and assessment of response to treatment of pediatric CNO bone lesions and could be used to monitor disease activity for clinical and research purposes.

Image guided sacroiliac joint corticosteroid injections in children: an 18-year single-center retrospective study

BACKGROUND

Sacroiliitis is commonly seen in enthesitis-related arthritis (ERA), a subtype of juvenile idiopathic arthritis (JIA). Sacroiliitis is characterized by the inflammation of the sacroiliac (SI) joints (+/- adjacent tissues). The treatment options include systemic therapy with or without corticosteroid SI joint injections. Image guided SI joint injections are frequently requested in pediatric patients with sacroiliitis. The purpose of this study was to evaluate the feasibility and efficacy of SI joint injections in children with sacroiliitis.

METHODS

A retrospective study of patients referred to Interventional Radiology (IR) for SI joint corticosteroid injections (2000-2018). Clinical information was collected from Electronic Patient Charts and procedural details from PACS. Efficacy was determined clinically, by MRI, or both when available.

RESULTS

50 patients (13.8 years; M:F = 35:15) underwent image-guided SI joint corticosteroid injections. Most common indications were JIA (84%) and inflammatory bowel disease (14%). 80% had bilateral injections. 80% were performed under general anesthesia and 20% under sedation. The corticosteroid of choice was triamcinolone hexacetonide in 98% of patients. Needle guidance and confirmation was performed using CT and fluoroscopy (54%), Cone Beam CT (CBCT, 46%), with initial ultrasound assistance in 34%. All procedures were technically successful without any complications. 32/50 patients had long-term follow-up (2 years); 21/32 (66%) had clinical improvement within 3-months. Of 15 patients who had both pre- and post-procedure MRIs, 93% showed short-term improvement. At 2 years, 6% of patients were in remission, 44% continued the same treatment and 47% escalated treatment.

CONCLUSION

Image-guided SI joint injections are safe and technically feasible in children. Imaging modalities for guidance have evolved, with CBCT being the current first choice. Most patients showed short-term clinical and imaging improvement, requiring long-term maintenance or escalation of medical treatment.

Spondyloarthritis Research Consortium of Canada sacroiliac joint inflammation and structural scores: change score reliability and recalibration utility in children

Background

The SPARCC sacroiliac joint inflammation (SIS) and structural (SSS) scores are reliable measures to quantify abnormalities in the pediatric sacroiliac joint. We aimed to evaluate the utility of online calibration modules for the SIS and SSS and the reliability of their component change scores.

Methods

Change score reliability of 6 raters was assessed by overall and pairwise intraclass correlation coefficients (ICCs) before and after the use of real-time iterative calibration (RETIC) modules for both the SIS and SSS comprised of 20 adult cases. Acceptable ICC for change scores was > 0.7 for SIS and > 0.5 for all SSS components. Sensitivity to change was assessed by the standardized response mean (SRM).

Results

In scoring exercise 1, the SIS had acceptable reliability with a change score ICC of 0.80 and sclerosis was the only SSS lesion that met the acceptability threshold with a change score ICC of 0.52. After RETIC calibration, the SIS overall (ICC = 0.83) and mean pairwise (ICC = 0.83) change scores remained reliable with a large SRM (0.90). All SSS components except sclerosis met the overall and mean pairwise change score ICC acceptability thresholds—backfill: overall = 0.54, mean pairwise = 0.50; fat metaplasia: overall = 0.65, mean pairwise = 0.57; erosion: overall = 0.60, mean pairwise = 0.58; and ankylosis: overall = 0.96, mean pairwise = 0.96. The SSS RETIC module augmented the number of SSS components surpassing the acceptability threshold from 1 to 4. Sensitivity to change, as measured by the SRM, was large for erosion (0.96), moderate for backfill (0.55) and sclerosis (0.70), and small for fat metaplasia (0.36) and ankylosis (0.28).

Conclusion

RETIC modules improved the overall reliability of SPARCC SIS and SSS change scores for previously calibrated raters. SIS recalibration was not as helpful to the most experienced raters who achieved high levels of agreement before recalibration. The SPARCC SIS and all SSS components except sclerosis are reliable measures to quantify change over time in children. A pediatric-specific RETIC tool should be developed to enhance the calibration of readers.