Imaging in rheumatoid arthritis, psoriatic arthritis, axial spondyloarthritis, and osteoarthritis: An international viewpoint on the current knowledge and future research priorities

Imaging in inflammatory arthritis: progress towards precision medicine

Imaging techniques such as ultrasonography and MRI have gained ground in the diagnosis and management of inflammatory arthritis, as these imaging modalities allow a sensitive assessment of musculoskeletal inflammation and damage. However, these techniques cannot discriminate between disease subsets and are currently unable to deliver an accurate prediction of disease progression and therapeutic response in individual patients. This major shortcoming of today's technology hinders a targeted and personalized patient management approach. Technological advances in the areas of high-resolution imaging (for example, high-resolution peripheral quantitative computed tomography and ultra-high field MRI), functional and molecular-based imaging (such as chemical exchange saturation transfer MRI, positron emission tomography, fluorescence optical imaging, optoacoustic imaging and contrast-enhanced ultrasonography) and artificial intelligence-based data analysis could help to tackle these challenges. These new imaging approaches offer detailed anatomical delineation and an in vivo and non-invasive evaluation of the immunometabolic status of inflammatory reactions, thereby facilitating an in-depth characterization of inflammation. By means of these developments, the aim of earlier diagnosis, enhanced monitoring and, ultimately, a personalized treatment strategy looms closer.

Imaging of Rheumatological Disorders

Early diagnosis and treatment of many rheumatological conditions has become crucial in order that drug therapies can be started before irreversible structural damage occurs. Both MR imaging and ultrasound play a valid role in the pathway of many of these conditions. The imaging findings as well as relative merits are described in this article as well as limitations that must be kept in mind when interpreting the imaging. Both conventional radiography and computed tomography also add important information in certain cases and should not be forgotten.

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.

Dermatologists' Role in the Early Diagnosis of Psoriatic Arthritis: Expert Recommendations

Psoriatic arthritis is a common type of inflammatory arthritis found in up to 40% of patients with psoriasis. Because skin involvement usually precedes joint involvement, dermatologists play a key role in early detection. Early diagnosis is important for reducing the risk of irreversible structural damage, attenuating the deterioration of physical function, and improving patients' quality of life. This consensus statement was drafted by a group of 9 dermatologists and 1 rheumatologist to provide simple recommendations to help dermatologists screen for psoriatic arthritis in patients with psoriasis. The experts offer consensus-based guidelines that draw on a review of available scientific evidence and on experience acquired in routine clinical practice.

Sentinel joint scoring in rheumatoid arthritis: an individualized power Doppler assessment strategy

OBJECTIVE

Musculoskeletal ultrasound quantifies the total synovial inflammatory burden in rheumatoid arthritis (RA) but is time consuming when scanning numerous joints. This study evaluated a novel patient-centered method for constructing a longitudinal ultrasound score in RA patients.

METHODS

Fifty-four RA patients starting intravenous tocilizumab were evaluated with power Doppler ultrasound (PDUS) of 34 joints and DAS28-ESR was assessed at baseline and weeks 4, 12, 16, and 24. The sentinel joint score (SJS) was derived from the reduced subset of joints with PDUS ≥ 1 at baseline. Total PDUS (tPDUS) score and US7 were also calculated. Changes in tPDUS and SJS were correlated. Effect sizes were calculated for tPDUS, SJS, and US7. The proportion of "flipped" joints without baseline PDUS signal that later developed PDUS signal was estimated.

RESULTS

At baseline, 1236/1829 joints scanned (67.5%) did not have PDUS signal. The proportion of "flipped" joints at 24 weeks was 5.6% for ≥ 1, 2.9% for ≥ 2, and 1.0% for = 3 PD. tPDUS and SJS scores were highly correlated (r = 0.91 to 0.97). Overall the effect sizes for tPDUS, SJS, and US7 increased over 24 weeks, where SJS was the highest (SJS 1.00 4-week, 1.07 12-week, 1.26 24-week) and tPDUS and US7 were comparable (tPDUS 0.32 4-week, 0.52 12-week, 0.84 24-week; US7 0.23 4-week, 0.52 12-week, 0.74 24-week).

CONCLUSION

In RA patients starting a biologic, scanning only joints with baseline PDUS signal can substantially reduce the number of joints requiring follow-up scanning by 67.5% and improves feasibility. "Flipped" joints are infrequently seen after starting therapy.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01717859 Key messages • Only a small percent of joints develop power Doppler signal after baseline scanning. • Changes in the SJS correlate well with changes in clinical activity measured by DAS28-ESR over time. • The SJS effect size is higher than total PDUS and US7 scores, and may improve examination feasibility.

Magnetic Resonance Imaging of Enthesitis in Spondyloarthritis, Including Psoriatic Arthritis-Status and Recent Advances

Enthesitis, inflammation at the attachment sites of tendons, ligaments, fascia, and joint capsules to bones plays a critical role in the pathogenesis of spondyloarthritis (SpA), including psoriatic arthritis (PsA). Magnetic resonance imaging (MRI) has aided in a better understanding of pathophysiology, early diagnosis, prognostication, therapeutic outcomes, and follow up of enthesitis. The concept of enthesitis as a focal insertional pathology has transformed over the past decade, with the help of MRI, to a more widespread entity involving both bone and surrounding soft tissues. The utility of MRI in the differential diagnosis of suspected enthesitis has recently been explored. With the emergence of the treat-to-target concept, and a domain-based approach in the management of SpA, objective and sensitive monitoring of response to targeted therapy becomes prudent. Properties like high sensitivity, ability to image intra-osseous pathology along with surrounding structures exemplify the utility of MRI technology. Considering the lack of a comprehensive, validated MRI score the Outcome Measures in Rheumatology (OMERACT) MRI in Arthritis Working Group, informed by a systematic literature review, developed the first international, consensus-based MRI-scoring system, combined with MRI definitions of pathologies for enthesitis in patients with spondyloarthritis (SpA) and PsA. An atlas with representative images of each grade of the scoring system was subsequently developed by the group to aid readers interested in using the heel enthesitis MRI scoring system (HEMRIS). The HEMRIS can find utility in clinical trials targeting enthesitis as the primary outcome. MRI also finds value for global assessment of the total burden of enthesitis. The concept of whole-body MRI (WBMRI), enabling visualization of entheses throughout the body using a single image is relatively new. The MRI whole-body score for inflammation in peripheral joints and entheses (MRI-WIPE) is a promising scoring system, which is undergoing further testing in clinical trials and longitudinal cohorts evaluating global measures of inflammation at entheses. This review discusses the role of MRI in diagnosis and monitoring of enthesitis in SpA and PsA, along with recent advances in the field, based on published literature.