By Stefan Cristian Dinescu, Razvan Adrian Ionescu, Horatiu Valeriu Popoviciu, Claudiu Avram, and Florentin Ananu Vreju
Rheumatologists manage patients with rheumatic diseases, which encompass a wide range of musculoskeletal pathologies. Rheumatic diseases include connective tissue diseases (eg, systemic lupus erythematosus, rheumatoid arthritis [RA], scleroderma, dermatomyositis/polymyositis, Sjögren syndrome, and mixed connective tissue disease), spondyloarthropathies (eg, ankylosing spondylitis, reactive arthritis, psoriatic arthritis), degenerative arthritis, metabolic disorders (eg, gout, pseudogout, other forms of crystal-induced arthritis), septic arthritis, and other diseases that affect the joints, bone, cartilage, tendons, and ligaments. Routine clinical evaluations that consist of a thorough history and physical examination, laboratory testing, and digital radiography can often establish the presence of arthritis. However, it can sometimes be challenging to differentiate between inflammatory and degenerative causes, especially when clinical signs are sparse and serology tests are negative. Without clarification of the exact location of the pathologies and the degree of inflammation, rheumatologists may inadvertently assess patients incorrectly, leading to inappropriate patient care.
Sonography is a cost-effective, readily available, noninvasive imaging technology used in the evaluation of the musculoskeletal system. Musculoskeletal ultrasound (MSUS) allows clinicians to visualize multiple anatomic regions in real-time and allow side-by-side comparisons with other imaging studies. In addition, MSUS facilitates the evaluation of several joints simultaneously, including functional assessments, as well as visualizing pathophysiological changes such as synovitis, tenosynovitis, bone erosions, and crystal deposits, which makes it an effective way to identify and differentiate the most common types of inflammatory arthritis. The use of sonography in a rheumatology practice also can also guide local procedures, which may include synovial fluid aspiration, therapeutic injections, nerve blocks, or soft-tissue biopsies. In order for sonographers to provide the highest quality images to clinicians and referring physicians, it is essential that the nuances of MSUS are mastered and understood. This textbook chapter will review the evidence for the application of MSUS in rheumatology and describes its role in diagnosis, monitoring, and prognosis of patients with various musculoskeletal diseases and disorders. Sonographic features of many musculoskeletal pathologies on screen are described and information for performing successful studies when imaging for suspected conditions or diseases will be presented.