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Lightscan imaging may allow sensitive detection of joint changes in patients with RA, OA
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Lightscan photo-optical imaging may offer sensitive image detection to track inflammatory changes in patients with rheumatoid arthritis and osteoarthritis in proximal interphalangeal joints, according to recently published research.
Researchers studied images and analysis of 668 proximal interphalangeal joints (PIP) in 87 patients with rheumatoid arthritis (RA) or osteoarthritis (OA) from the Rheumatology Outpatient Clinic of the University Hospital Charité, Berlin, and compared the results of Lightscan photo-optical imaging (POI) with clinical examination, grayscale ultrasound (GSUS) and power Doppler ultrasound (PDUS). Thirty-eight patients had RA, 21 patients had OA and 28 participants served as a healthy control group without any evidence of inflammatory joint disease.
All participants underwent joint examination and laboratory tests, including C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR), along with rheumatoid factor and anti-cyclic citrullinated protein antibodies. Disease Activity Score in 28 (DAS28) joints, DAS28 with ESR (DAS28-ESR) and tender and swollen joint counts were measured to assess disease activity. Only the VAS for disease activity (0-100 mm) was used to evaluate patients with OA.
The standard reference method for comparison was musculoskeletal ultrasound using an Esaote MyLab Twice ultrasound device with a high-resolution 8 MHz to 18 MHz linear array transducer on all participants. An experienced ultrasound examiner assessed the PIP joints following the guidelines set forth by Outcome Measures in Rheumatology Meeting and the European League Against Rheumatism criteria. PIP joints were evaluated on a scale of 0 to 3 for synovitis in GSUS mode and in PDUS mode to evaluate tenosynovial vascularity from the palmar and dorsal views.
The POI was conducted by transilluminating the PIP joints with laser diodes at three wavelengths (670 nm, 820 nm and 904 nm), and a charge-coupled device camera was used to record the images of scattered light into black-and-white 8-bit images. False color was used to transform the images for analysis.
Compared with clinical assessments, POI findings were in agreement with swollen and tender joints and positive findings presented in 257 of 699 joints. No evaluation was possible in 45 joints due artefacts from motion, according to the researchers.
With GSUS, 150 positive joints were detected and 54 positive results were seen using PDUS. In the palmar view, PDUS revealed 25 joints. Tenosynovitis was detected in 62 joints.
Compared with ultrasound, the sensitivity of POI was 74% and specificity was 93% after analysis using receiver operator characteristics.
Positive findings of inflammatory changes were seen in 43 of 59 patients with RA and OA, or in 25 of 38 patients with RA and in 18 of 21 patients with OA. Twenty-six of 28 healthy participants had negative findings. – by Shirley Pulawski
Disclosure: The researchers report the study was supported by the Bundesministerium für Bildung und Forschung project “ArthroMark,” subproject no. 7 “Clinical study on Biomarkers and Imaging.”
Perspective
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Leonard H. Calabrese, DO
Office evaluation of patients with inflammatory arthritis can be complex at times. While clinical exams have served us well, there are few people who believe this is the enduring gold standard for optimal disease management. Patients who are tender and even swollen are influenced by many factors and global assessments of pain. Toward building a better “mousetrap,” MRI and ultrasound offer increased sensitivity and precision, but are hampered by high costs and, in the case of office ultrasound, operator skill and time.
The report from Amitai and colleagues from the Charitie in Berlin give us insights into a promising new technique in the form of photo optical imaging (POI). In a robust study of 688 proximal interphalangeal joints joints in 87 patients, which included 38 patients with rheumatoid arthritis (RA), 21 patients with osteoarthritis (OA) and 28 healthy subjects, they compared POI to ultrasound (grey scale and power Doppler) and clinical exam. They found POI is more sensitive for inflammation in patients with RA and OA in differentiation for healthy subjects and correlated well with both grey scale and power Doppler. Also, POI was also found to be more sensitive than the clinical exam.
The technique is quick and easy and can be performed by a medical assessment and scored rapidly. The technique has limitations, such as movement artifacts, and is hampered by significantly altered anatomy. Nevertheless, POI is appealing from many perspectives and rheumatologists should follow its development with interest.
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