Background/Purpose: Arthrosonography has proven to be a sensitive and reliable, but time-consuming method for the evaluation of arthritis in small joints of patients with RA (1, 2). The automated breast volume scanner (ABVS) was developed to acquire series of consecutive B-mode pictures of the female breast. In a pilot study, we have recently described the possible application of this system to finger joints of RA patients (3). This study was performed to confirm the value of ABVS in detecting swelling and erosions of the finger, wrist and foot joints in patients with RA in comparison to conventional manual ultrasound (mUS).

Methods: Patients with RA were assessed by clinical and sonographic examination of the MCP, PIP, wrist and MTP joints. In addition, data for DAS-28, SDAI, CDAI and HAQ was gathered. ABVS was conducted using the ACUSON S2000 (Siemens, Germany), mUS was performed on MyLab 70 (Esaote, Italy). The ABVS transducer was equipped with a linear array of 11 MHz and each automatic sweep of the scanner generated 15.4 x 16.8 cm x 2.5 cm volume data sets. The system was set to perform an automatic scanning time of 65 seconds per scan with a slice thickness of 0.5 mm. mUS was performed with a 8-18 MHz linear transducer.

Results: We included 44 patients with established (n=30) and early (n=14) RA with a mean DAS28 of 4.4 ± 1.8 and a mean swollen joint count of 8 ± 6.3. In total, 1548 small joints were assessed. ABVS revealed synovitis in 20,7 % of the examined joints, compared to 18.4 % with mUS. Erosions were seen in 196 joints with ABVS and in 168 joints with mUS. Correlation of US findings with clinical activity parameters were weak for both methods except for the swollen joint count with 0.41 for ABVS and 0.73 for mUS and physicians’ global assessment with 0.43 and 0.57 for ABVS and mUS, respectively. Defining mUS as gold standard, the sensitivity of ABVS for the detection of joint swelling was 0.64 with a specificity of 0.88. Concerning erosions, sensitivity and specificity were 0.64 and 0.88. The negative predictive value was 0.91 for joint swelling and 0.92 for erosions. The interrater and intrarater agreements were 0.83 and 0.85 for ABVS and 0.84 and 0.88 for mUS, respectively.

Conclusion: ABVS is a simple and time-sparing method for the detection of joint swelling and erosions. Compared to manual ultrasound as gold standard, ABVS has an acceptable sensitivity and a very good negative predictive value which makes it a promising screening method for small joint synovitis in RA.

References:

1. Witt M et al., Arthritis Rheum. 2013 Jul;65(7):1694-701

2. Witt M et al., J Rheumatol. 2014 Mar;41(3):422-8

3. Mueller R et al., Arthritis Rheum 2013;65(10):S832

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/detection-of-synovitis-and-erosions-with-an-automated-ultrasound-system-data-from-a-prospective-cohort-with-early-and-established-ra/