Using Ultrasound to Improve Diagnostic Confidence and Management of Psoriatic Disease: Highlights From the GRAPPA 2023 Ultrasound Workshop

Overview of DUET

The first topic in the workshop, presented by Dr. Eder, was an overview of the DUET enthesitis scoring methodology. Enthesitis, which is the inflammation at the insertion of tendon, ligament, and capsule into bone, is a key domain of PsA.

Conventionally, the presence of enthesitis is ascertained by clinical examination by evaluating for tenderness at the entheseal sites, a method with significant limitations. The greater sensitivity of US compared to clinical examination for detecting enthesitis has been reported in numerous studies.^6,7 However, there is a lack of a validated sonographic enthesitis scoring system that reliably and accurately distinguishes PsA from non-PsA.

The DUET project is a GRAPPA-supported international, multicenter study that aims to develop a new sonographic enthesitis tool to differentiate patients with PsA from those without PsA and to assess the tool’s validity and reliability.

An SLR of PsA sonographic enthesitis instruments performed by the DUET investigators identified significant limitations regarding the existing scoring systems.⁸ It was noted that numerous studies used tools validated in axial spondyloarthritis (axSpA), a condition in which the distribution of enthesitis differs from PsA, and there was a lack of agreement regarding the number and location of entheseal sites included in each scoring tool.

Following the SLR, a pilot study was conducted in Toronto where 50 patients with PsA and 50 controls underwent sonographic evaluation of 22 entheseal sites. This study identified potential entheseal sites and US lesions with the potential to distinguish PsA from controls. These findings informed the selection of entheseal sites for the DUET study.⁹

A detailed DUET protocol was presented during the GRAPPA 2019 annual meeting in Paris, France.¹⁰ In summary, prospective clinical and sonographic data were collected, and patients were divided into 3 groups: (1) patients with early PsA, (2) patients with psoriasis (PsO) without musculoskeletal symptoms, and (3) patients with noninflammatory rheumatic conditions without PsO. Recruiting sites were carefully selected depending on the availability of experienced sonographers and high-quality US devices. Training materials were developed, and participation in a prestudy training workshop for sonographers was a prerequisite to ensure standardization of US scanning technique and image acquisition. Eight entheseal sites bilaterally (a total of 16) in the upper and lower limbs were evaluated during the DUET study. The scoring of sonographic entheseal lesions is shown in the Figure.¹¹

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Figure 1.

Scoring of sonographic elementary lesions in the DUET study.¹¹

Both local and central readers scored the entheseal lesions. Central reading, carried out independently by 2 readers, will form the basis for the primary analysis and the development of the scoring instrument. Local reading will form part of the secondary analysis to assess the validity and generalizability of the scoring tool. The results of a reliability exercise were recently presented at the American College of Rheumatology Convergence in 2022, where moderate to substantial interrater agreement was achieved for most lesions, especially among central readers.¹¹

Study recruitment was successfully accomplished in March 2023, and the scoring of images by central readers has recently been completed. A total of 421 patients were recruited; the study population included 215 patients with early PsA, 100 patients with PsO without musculoskeletal symptoms, and 106 controls with noninflammatory rheumatic conditions without PsO.

Small hand-held probes: Will the promise deliver?

Dr. Aydin presented the second topic, introducing the concept of small HHUS devices.

Technological progress in the field of US has enabled HHUS devices to be created, many of which communicate wirelessly. In recent years, HHUS devices have entered the US market. Their use has been adopted by numerous medical specialties, with key advantages including a significantly lower equipment purchase cost and easier portability than cart-based US machines.¹² However, the performance of HHUS devices in evaluating the 5 targets of sonography (joints, tendon, enthesis, psoriatic plaque, and nail bed and nail plate) in PsA remains to be determined.¹³

Dr. Aydin outlined the methodology of a study by the GRAPPA Ultrasound Working Group that aims at validating HHUS devices for point-of-care use in rheumatology. Patients with peripheral PsA who present to the rheumatology outpatient clinic of 3 sites, which include Ottawa, Toronto, and Jacksonville, Florida, with at least 1 tender and 1 swollen joint, are being prospectively recruited. At recruitment, patients undergo MSUS examination of various anatomic sites according to a prespecified protocol with a standard US machine and a HHUS device.

The scanning protocol for each patient includes 24 joints, 20 entheses, 4 tendons, and 2 nails. A combination of small and large joints and entheseal sites have been included. The examinations are performed in B mode and power Doppler (PD) mode, with both devices and lesions scored using previously validated methods.

Moderate to almost perfect agreement was achieved on an interim analysis based on the reading of images for the first 10 patients, allowing the study to proceed to the next phase.¹⁴

Comparing the performance of 2 HHUS devices vs a console US machine (live demonstration and interactive group discussion)

To compare the performance of 2 different HHUS devices to a console US machine, MSUS of numerous joints and entheseal sites on patients with PsA was performed live by Dr. Aydin and Dr. Gurjit Kaeley. The examinations were performed in B mode and PD mode with both devices.

This demonstration prompted interactive discussions regarding the role of HHUS in the clinical care of patients with PsA and PsA research.

The key advantages identified included the relatively low cost and portability of HHUS devices.⁴ Additionally, as highlighted by other specialties, HHUS devices may facilitate more widespread and enhanced MSUS training for rheumatology trainees.¹⁵ Some specific portable HHUS devices are equipped with the use of artificial intelligence to assist with image optimization and interpretation. These features may improve the consistency of image capture and increase the likelihood of acquiring diagnostically relevant images.¹⁶

However, whether HHUS devices can be used in the clinical care of patients with PsA to assess structural damage and the presence of inflammatory disease activity remains to be determined. An important concern is whether the Doppler mode (an essential component of MSUS) of HHUS devices can accurately identify the presence of inflammatory lesions. In a recent study, a HHUS device’s PD mode did not adequately identify hypervascularization in the joints and surrounding periarticular structures.¹⁷ Whether different HHUS devices have different sensitivities to detect Doppler signal is yet to be explored.

Despite the potential advantages of incorporating the use of portable US devices in rheumatology practice, due consideration should be given to their limitations.

First, these US probes are not designed for prolonged scanning. Depending on the device used, the probe temperature rises after a period of continuous scanning. In the case of specific devices, the automatic cooling function is activated, and imaging must be stopped until the system has cooled down.¹⁶

Further, the limited battery life of the currently available HHUS probes is a clear disadvantage over standard US systems. This could possibly affect scanning sessions and result in significant interruptions.¹⁶

Another potential issue with HHUS devices highlighted during the workshop was the relatively heavier weight of some probes, which can result in sonographer fatigue, thus limiting the utility of some devices for more extensive scanning periods.

Notably, most of these US devices incorporate cloud-based storage systems for archiving the acquired examination for future reference. These archiving systems often require a paid subscription service, which adds to the running costs of HHUS probes.¹⁶ In addition, cloud-based storage systems may not be approved by some hospitals due to concerns around privacy.

Finally, the consensus from this workshop was that these HHUS devices may help evaluate a clearcut pathology and help make clinical decisions in resource-limited settings. However, for detailed scanning, formal conventional US equipment is required. A recent survey among GRAPPA members identified the cost of US devices as a significant barrier in clinical practice.⁵ This barrier may, at least in part, be removed by the lower acquisition cost of HHUS.

This feedback will guide the development of the research agenda by the US working group.