French researchers have found that ultrasound can detect more joint erosion in rheumatoid arthritis (RA) patients than radiography, according to a study published in the September issue of the European Journal of Radiology.
The findings show the modality can serve as a powerful tool for the diagnosis and management of arthritis, noted a team led by Dr. Camille Roux of the University Hospital of Nancy in Vandoeuvre-lès-Nancy, France.
Ultrasound offers "many advantages (accessibility, cost, and lack of irradiation) with good intra-and interreliabilities for assessing structural damage and especially erosion in RA and in other musculoskeletal diseases," the group wrote.
Common disease
Rheumatoid arthritis is the most common inflammatory joint disease, and the clinical recommendation is for close management of it, Roux stated. Radiography is considered the gold standard for visualizing and quantifying RA, but musculoskeletal ultrasound is increasingly used due to its lack of ionizing radiation (Eur J Radiol, September 2019, Vol. 118, pp. 10-18).
"Musculoskeletal ultrasound is booming in clinical practice for the diagnosis and evaluation of inflammatory lesions from inflammatory disorders, and it has been proved to be effective in the evaluation of bone erosions in various musculoskeletal diseases: osteoarthritis, gout, and psoriatic arthritis," the authors wrote. "In RA, many studies have shown that ultrasound can detect more erosions than x-ray at the joint level, especially at an early stage of the disease, with higher sensitivity and specificity than x-ray when a CT scan is taken as the gold standard imaging method."
The group conducted a study to assess ultrasound's performance in diagnosing erosive RA compared with osteoarthritis, tracking sensitivity and specificity. The research included 168 patients, 122 of whom had rheumatoid arthritis and 46 of whom had osteoarthritis. Of patients with rheumatoid arthritis, 32 had the disease less than two years ("early") and 90 had the disease more than two years ("late"). Patients were assessed for joint erosion, which was scored on six bilateral joints with a four-grade scale (metacarpophalangeal [MCP] joints 2, 3, and 5 and metatarsophalangeal [MTP] joints 2, 3, and 5).
On x-ray, 42 rheumatoid arthritis patients (six with early disease and 36 with late disease) and five osteoarthritis patients had erosive disease, for a sensitivity of 34.4% and a specificity of 89.1% in that modality.
On ultrasound, 95 rheumatoid arthritis patients (21 with early disease and 78 with late disease) and 12 osteoarthritis patients had erosive disease. Ultrasound had higher sensitivity values than x-ray, and a higher specificity value when it came to identifying at least two or more worn joints. It also had excellent agreement with x-ray for all joints -- both erosion on ultrasound of at least one erosion of grade 2 (92.8%) and at least two eroded joints (90.4%).
| Ultrasound performance identifying joint erosion | ||||
| Erosion on ultrasound ≥ grade 2 | ≥ 2 eroded joints on ultrasound | |||
| Sensitivity | Specificity | Sensitivity | Specificity | |
| Ultrasound | 66.4% | 89.1% | 68% | 100% |
The researchers also found that in both late and early RA, the MTP 5 joints, the MCP 2 joints, and the MCP 5 joints were the most commonly worn joints identified by ultrasound. In osteoarthritis patients, the MCP 2 and MTP 5 joints were the most frequently eroded on ultrasound.
A reliable tool
The study shows that ultrasound is a reliable tool for diagnosing erosive RA, and could be used along with x-ray when it comes to diagnosing early disease, according to the team.
"We demonstrated that bone erosions assessed by ultrasound were reliable and may be observed in both diseases [i.e., RA and osteoarthritis], with a higher prevalence and severity in RA," the group concluded. "More in early RA than in established RA, ultrasound examination and radiography should be performed together in order to optimize the diagnosis of erosive disease."
