![]() ![]() Scans were acquired under the following standard conditions: camera positioned perpendicular to the subject's forearm at a stand-off distance of 0.8 m, camera height of 0.8 m, and camera declined to 45° from horizontal. The camera was operated via a laptop computer using Polygon Editing Tool (version 1.22 Konica Minolta Sensing Americas, Inc.). Its manufacturer-reported resolution and accuracy are less than 0.2 mm in all axes. Scans were acquired using a Minolta Vivid 910 (Konica Minolta Sensing Americas, Inc., Ramsey, NJ, USA), a laser line triangulation scanner that produces a 640 × 480-pixel 3D image. Fixed objects, necessary to create and align 3D models from different sessions, were attached to the base of this splint. A forearm-based hand splint was designed to minimize movement and standardize hand position and pose between sessions (Figure (Figure1a). The image acquisition and processing technique is outlined in Figure Figure1. We conducted a proof-of-concept study to determine whether two of the cardinal signs of disease activity in arthritis (swelling and warmth) can be reliably quantified using existing three-dimensional (3D) and thermal digital imaging devices. However, MRI involves substantial time and cost, exposure to contrast agents, and the need for sedation in young children. Magnetic resonance imaging (MRI) has proven to be more sensitive and reliable than clinical examination in the detection of synovitis and has the ability to quantify changes in synovial volumes and erosions. Ultrasound can quantify changes in effusion and synovitis, but it is highly user-dependent. For instance, plain radiographs are insensitive to early changes. However, all of the current technologies have limitations. Such a measure could be used to assess response to therapy in both the clinical and research settings.Ī number of imaging technologies have been studied in an effort to improve the assessment of arthritis activity. An unbiased and reliable measure of the inflammatory state of the joint would improve the ability to quantify disease activity. Studies of intra- and inter-observer variability regarding these measures have demonstrated high coefficients of variation (CVs) and low intra-class correlation coefficients (ICCs). Unfortunately, carefully designed studies have repeatedly shown poor reproducibility of physician-assessed swollen joint counts and active joint counts. An essential component of these outcome measures is the assessment of the number of joints with active arthritis. ![]() To determine the efficacy of these new drug therapies, outcome measures, such as the American College of Rheumatology (ACR) 20 in RA and the ACR 30 in JIA, have been developed and accepted by international regulatory agencies. Over the last decade, significant progress has been made in increasing the number pharmacological options available to treat these conditions. Rheumatoid arthritis (RA) and juvenile idiopathic arthritis (JIA) are chronic inflammatory conditions of the joints which can result in substantial morbidity and loss of function. CVs for volume and SDI were <1.3% and ICCs were greater than 0.99. Standard deviation (SD), coefficient of variation (CV), and intraclass correlation coefficients (ICC) were calculated for each quantitative measure to establish their reliability. HDI values from 18 wrist and 9 MCP regions were obtained from 17 patients with active arthritis and compared to data from 10 wrist and MCP regions from 5 controls. Seven wrists and 6 MCP regions from 5 subjects with arthritis were used to develop and validate 3D image acquisition and processing techniques. Specialized software generated 3 quantitative measures for each joint region: 1) Volume 2) Surface Distribution Index (SDI), a marker of joint shape representing the standard deviation of vertical distances from points on the skin surface to a fixed reference plane 3) Heat Distribution Index (HDI), representing the standard error of temperatures. A Minolta 910 Vivid non-contact 3D laser scanner and a Meditherm med2000 Pro Infrared camera were used to create digital representations of wrist and metacarpalphalangeal (MCP) joints. ![]()
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