Superb microvascular imaging evaluating joint lesion scores in rheumatoid arthritis compared with power Doppler imaging: A meta-analysis

The Use of Superb Microvascular Imaging in Evaluating Rheumatic Diseases: A Systematic Review

Background and Objectives: Superb microvascular imaging is an advanced Doppler algorithm that seems to be useful in detecting low-velocity blood flow without using a contrast agent. Increasing evidence suggests that SMI is a more sensitive tool than conventional Doppler techniques for evaluating rheumatic diseases, especially inflammatory arthritis. We aimed to assess the use of SMI in evaluating joints and extraarticular structures. Materials and Methods: Two reviewers independently reviewed the literature to provide a global overview of the possibilities of SMI in rheumatology. Original English-language articles published between February 2014 and November 2022 were identified through database (PubMed, Medline, Ebsco, the Cochrane Library, and ScienceDirect) searching, and analysed to summarise existing evidence according to PRISMA methodology. Inclusion criteria covered original research articles reporting applications of SMI on rheumatic diseases and musculoskeletal disorders secondary to rheumatic conditions. Qualitative data synthesis was performed. Results: A total of 18 articles were included. No systematic reviews fulfilled our inclusion criteria. Most studies focused on characterising the synovial vascularity of rheumatoid arthritis. There have been several attempts to demonstrate SMI's value for evaluating extra-articular soft tissues (fat pads or salivary glands) and large-diameter vessels. The quantitative importance of SMI vascular indices could become a useful non-invasive diagnostic marker. Studies on therapeutic applications are still scarce, and the majority of studies have gaps in reporting the methodology (ultrasound performance technique and settings) of the research. Conclusions: SMI has proved to be useful in characterising low-flow vascularity, and growing evidence indicates that SMI is a non-invasive and lower-cost tool for prognostic assessment, especially in inflammatory arthritis. Preliminary findings also suggest potential interest in evaluating the effect of treatment.

Ankle and Foot: Focus on Inflammatory Disease

The ankle and foot have numerous bones and complex joints that can be affected by several types of inflammatory arthritis with different patterns and various radiologic signs, depending on the phase of the disease. Involvement of these joints is most frequently seen in peripheral spondyloarthritis and rheumatoid arthritis in adults and juvenile idiopathic arthritis in children. Although radiographs are a mainstay in the diagnostic process, ultrasonography and especially magnetic resonance imaging allow early diagnosis and are crucial diagnostic tools. Some diseases have typical features based on target populations (e.g., adults versus children, men versus women), but others may have overlapping imaging characteristics. We highlight key diagnostic features and describe appropriate investigations to guide clinicians toward the correct diagnosis and provide support during disease monitoring.

Superb microvascular imaging is as sensitive as contrast-enhanced ultrasound for detecting synovial vascularity in rheumatoid arthritis

BACKGROUND

Detection of synovitis is essential for assessing rheumatoid arthritis (RA) activity and predicting prognosis. This study aimed to compare the diagnostic performance of superb microvascular imaging (SMI) with that of contrast-enhanced ultrasound (CEUS) in patients with RA in clinical remission.

METHODS

SMI and CEUS were applied to 63 patients with active RA and 48 patients with RA in clinical remission. Differences in positive synovial vascularity (SV) and its semi-quantitative scale were observed, and the correlations of SMI and CEUS results with C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and rheumatoid factor (RF) were analyzed.

RESULTS

For the 63 joints with active RA, the detection rates of SV as determined by SMI and CEUS were 90.5% (95% CI: 83.0-97.9%) and 93.7% (95% CI: 87.5-99.8%), respectively, with no significant difference observed between the two modalities (t=-1.137; P=0.260). There was good agreement between the two modalities in detecting positive blood flow (Kappa =0.784) and blood flow signal score (Kappa =0.792). For the 48 joints with clinical remission, the detection rates of SV determined by SMI and CEUS were 79.2% (95% CI: 67.2-91.1%) and 83.3% (95% CI: 72.4-94.3%), respectively, with no significant difference found between the two modalities (t=1.000; P=0.322). There was high consistency between the two modalities in detecting positive blood flow (Kappa =0.727) and blood flow signal score (Kappa =0.661). The vascularity scores of SMI and CEUS were positively correlated with CRP, ESR, and RF in the joints with active RA, but not in those with clinical remission.

CONCLUSIONS

SMI is as sensitive as CEUS for detecting vessels in the synovium and displaying local SV in patients with RA who achieve clinical remission.

Advances in Ultrasound Imaging in Rheumatology-What Do They Mean and What Challenges Do They Pose? The Example of Microvascular Imaging

Musculoskeletal ultrasound is an important tool for the monitorization of inflammatory rheumatic diseases, with subclinical synovitis being frequently detected in ultrasound scans of patients in clinical remission. It has been shown, for example, that the presence of Power Doppler signal synovial membrane has prognostic value for patients with rheumatoid arthritis. Microvascular imaging technologies significantly improve the sensitivity for slow-flow vessels and may potentially detect subclinical inflammation when Power Doppler fails to do so. The authors briefly discuss the implications of the use of such techniques in rheumatology setting and review available evidence.

Pachydermodactyly: the role of ultrasonography, superb microvascular imaging, and elastography in diagnosis

Pachydermodactyly is a rare and benign superficial fibromatosis characterized by painless and progressive swelling of periarticular soft tissues of the proximal interphalangeal (PIP) joints, most commonly of both hands. There is no tenderness, warmth, morning stiffness, or reduced range of motion associated. Our purpose is to highlight the diagnostic utility of ultrasonography, superb microvascular imaging (SMI), and elastography in pachydermodactyly. We report the case of a 15-year-old adolescent white boy, with a 6-month history of insidious and progressive, asymptomatic swelling of the lateral and dorsal regions of the metacarpophalangeal (MCP), and PIP joints of both hands. Articular ultrasonography showed thickening of the skin around the lateral regions of the PIP and MCP joints, with no synovitis, hydrarthrosis, or muscle, tendon, or bone changes. Strain elastography revealed lower elasticity in the aforementioned skin regions, corresponding to increased tissue hardness due to hyperkeratosis. No SMI or Doppler signals were detected in epidermal or dermal tissues, as well as in tendons, joints, and bone. This case report shows that ultrasonography, SMI, and elastography may play a significant role in the accurate diagnosis of pachydermodactyly and exclusion of alternative conditions. These imaging modalities have no ionizing radiation; they are fast, inexpensive, and performed on site. They do not require usage of contrast agents and thus can eliminate the need of invasive procedures such as skin biopsy. They also contribute to reduce health care costs with unnecessary complementary tests and inappropriate treatment.