High-Resolution US of Rheumatologic Diseases

Abstract

For the past 15 years, high-resolution ultrasonography (US) is being routinely and increasingly used for initial evaluation and treatment follow-up of rheumatologic diseases. This imaging technique is performed by using high-frequency linear transducers and has proved to be a powerful diagnostic tool in evaluation of articular erosions, simple and complex joint and bursal effusions, tendon sheath effusions, and synovitis, with results comparable to those of magnetic resonance imaging, excluding detection of bone marrow edema. Crystal deposition diseases including gouty arthropathy and calcium pyrophosphate deposition disease (CPPD) have characteristic appearances at US, enabling differentiation between these two diseases and from inflammatory arthropathies. Enthesopathy, which frequently accompanies psoriatic and reactive arthritis, also has a characteristic appearance at high-resolution US, distinguishing these two entities from other inflammatory and metabolic arthropathies. The presence of Doppler signal in examined joints, bursae, and tendon sheaths indicates active synovitis. Microbubble echo contrast agents augment detection of tissue vascularity and may act in the future as a drug delivery vehicle. Frequently, joint, tendon sheath, and bursal fluid aspirations and therapeutic injections are performed under US guidance. The authors describe the high-resolution US technique including gray-scale, color or power Doppler, and contrast agent-enhanced US that is used in evaluation of rheumatologic diseases of the wrist and hand and the ankle and foot in their routine clinical practice. This article demonstrates imaging findings of normal joints, rheumatoid arthritis, gouty arthritis, CPPD, psoriatic and reactive arthritis, and osteoarthritis.

High-Frequency and Ultra-High Frequency Ultrasound: Musculoskeletal Imaging up to 70 MHz

“…These examinations should be performed with linear transducers up to 20 MHz with B-mode, and power and color Doppler, with the latter tools helpful to detect active synovitis. 41 UHFUS of cartilage was first tested at 50 MHz in the mid-1990s (►Fig. 4).…”

Layered Approach to the Anterior Knee: Normal Anatomy and Disorders Associated with Anterior Knee Pain

“…At US, tophi appear as hypoechoic shadowing nodules with peripheral hyperechogenicity (126). Crystal deposits on articular cartilage produce a hyperechoic line at its outer margin that parallels the subchondral bone, resulting in the "double-contour" sign, an appearance seen in both symptomatic and asymptomatic gout (127). CT demonstrates hyperattenuating nodules, whereas dual-energy CT allows more accurate differentiation of urate from calcification (128).…”

Recommendations of the ESSR Arthritis Subcommittee on Ultrasonography in Inflammatory Joint Disease

“…Linear transducers of higher frequency or hockey-stick transducers with 12-to 18-MHz frequencies are used to examine smaller and more superficial joints, such as the joints of the hands and feet. 4 Optimal US imaging requires small movements of the US probe along with generous quantities of coupling jelly. It is important to apply minimal probe pressure and scan the whole area of the joint capsule in two perpendicular planes because pathology can be confined to one part of the joint only.…”