Musculoskeletal Ultrasound: A Valuable Tool for Diagnosing Rheumatic Illnesses

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Musculoskeletal (MSK) ultrasound is a valuable imaging modality for the practicing rheumatologist and provides an efficient tool with high diagnostic value in the evaluation of patients with musculoskeletal complaints. The use of MSK ultrasound has evolved in the U.S. due to the emergence of less-expensive, portable ultrasound units, which provide high-quality gray-scale and power Doppler signals. The American College of Rheumatology (ACR) has provided standardized training courses, as well a certification program, for the practicing rheumatologist, and such training is also available in many fellowship programs.¹

The diagnosis of rheumatoid arthritis (RA) can be challenging in certain clinical settings because crystalline arthropathies can be close mimics of RA. For example, palindromic RA can present with articular symptoms, which can resemble a crystalline process based on historical and clinical features.

The following cases demonstrate the usefulness of ultrasound in providing clues to the underlying diagnosis and highlight a case in which this imaging modality was helpful in assessing disease activity in an established RA patient, which altered the patient management.

Case 1

A 57-year-old male with a past medical history of RA was referred to rheumatology by his primary care physician (PCP). The patient had been diagnosed with RA four years earlier, with manifestations of bilateral hand symptoms along with high titer rheumatoid factor (RF) and anti-cyclic citrullinated peptide (CCP) antibodies. He was initially treated by a rheumatologist and had started oral methotrexate, but discontinued it after a few months due to his concerns of long-term drug toxicity. He did not follow up with his rheumatologist and remained off treatment for more than three years. During this time period, he tried numerous herbal products, along with acupuncture, with negligible improvement and was encouraged to follow up with rheumatology by his PCP.

MSK ultrasound can enhance diagnostic certainty for the diagnosis of RA because subtle clinical exam signs of synovitis or tenosynovitis can be quite obvious on ultrasound examination.

At the time of follow-up, his symptoms included mild pain and morning stiffness in his feet and hands (30 minutes’ duration) along with

(click for larger image)
Image 1: The photo (left) reveals subtle soft tissue swelling of the proximal portion of left thumb (arrow) corresponding to teno-synovial hypertrophy seen on this longitudinal gray-scale image of the proximal portion of the thumb. Doppler ultrasound of the same area (right): Power Doppler signals indicate inflammatory (high vascularity) signal of the surrounding tenosynovium deep to the flexor tendons reflective of tenosynovitis.