Feasibility of applying infrared thermal imaging for home monitoring of arthritis in children.

Background: Telemedicine has improved access to pediatric rheumatology care. A disadvantage to using virtual modality for evaluation of children with arthritis is the lack of an in-person, hands-on physical exam. Thermal imaging has been studied in the clinical setting with promising results. This study aims to determine the feasibility of procuring at-home thermal imaging, measuring the variability of in-home skin temperature measurements over three consecutive days, and to compare these measurements at home to ones obtained in the clinic setting.

Methods: Children with knee pain and/or swelling for a week or longer were enrolled and imaged with a smartphone-attached FLIR ONE PRO and Fluke handheld cameras followed by imaging with a FLIR camera at home for 3 consecutive days. Joint exam performed in the office was used as gold standard for joint assessment. A previously validated metric of temperature after within-limb calibration (TAWiC), defined as the temperature differences between the knee joint and ipsilateral mid-tibia, was used for all imaging studies.

Results: Fifty-three patients were enrolled and thirty-eight completed the imaging acquisition at home with analyzable images. When evaluating images of the knee and mid-tibia regions, images collected at home compared to in-office demonstrated consistently lower absolute temperatures. However, the calibrated temperatures (TAWiC) of the anterior and lateral views of the knee showed mild to moderate correlation across 3 days between home-acquired images and office-acquired images (r = 0.58, 0.26, 0.24 and r = 0.36, 0.41, 0.42, respectively). The sensitivity and specificity of detecting arthritis of the knee using TAWiC adjustments from previously defined thresholds were similar regardless of the setting of image acquisition (0.44 and 0.79).

Conclusions: This study demonstrates the feasibility of applying TAWiC for arthritis detection through a smartphone-based infrared thermal camera operated by families at home. Further investigation on a larger scale is needed prior to implementation of this process in the telemedicine setting.