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Smartphone camera presents potential alternative for diabetic foot ulcer detection

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February 21, 2019

Diabetic foot ulcer can be detected effectively using an infrared camera on a smartphone, even when compared with a high-end infrared camera usually utilized in clinical practice, according to findings published in Diabetes Research and Clinical Practice.

“With [infrared], temperature profiles of the foot can be studied in more detail than with hand-held thermography, and the identification of (pre-signs of) [diabetic foot ulcer] may become automated with these devices, reducing the effort by the participants and the clinician to acquire and assess images,” R.F.M. van Doremalen, MSc, a researcher at the University of Twente in Enschede, the Netherlands, and colleagues wrote. “However, broad implementation of thermal assessment is still obstructed. A major reason are the costs of [infrared]-cameras, as well as the need for complex data analysis.”

Van Doremalen and colleagues tested the second-generation FLIR One camera on a Motorola XT1642 Moto G4 Plus smartphone with 32 consecutively recruited adults with type 1 diabetes and current or recently healed diabetic foot ulcer (mean age, 67 years; 25% women). Participants were recruited from the outpatient diabetic foot clinic of the Hospital Group Twente in Almelo, the Netherlands.

Each participant had images taken with the smartphone camera and a FLIR SC305 thermal camera, which was labeled the “high-end” option. Two images of each foot were taken by the smartphone camera and the high-end camera. Once images were taken, the researchers determined the average temperature for the entire plantar foot as well as in the hallux, first, third and fifth metatarsal heads, metatarsocuneiform joint, cuboid, third and fifth toe and lateral metatarsocuneiform joint.

Intraclass correlation coefficient (ICC) and mean difference based on Bland-Altman plots were used as comparative measures between the two camera types. The threshold for excellent agreement in ICC was a measure of 0.9 or higher. The threshold for mean difference was less than 0.15. Based on these factors, the researchers found that the smartphone camera compared favorably with the high-end camera in the entire plantar foot (ICC = 0.987; mean difference, –0.14) and the nine individual regions (ICC = 0.981; mean difference, –0.06). The lowest ICC reading in any region was 0.929 in the first metatarsal heads while the greatest mean difference was in the cuboid (–0.18), which was the only region to fall outside of the threshold.

“The promising outcomes on the validity of the smartphone-based [infrared] camera bring implementation of this advanced monitoring tool much closer to daily clinical practice,” the researchers wrote, while adding that additional steps will still be required. “For home implementation, an important development would be the creation of specific acquisition and automatic assessment algorithms for the smartphone application to assess the [infrared] images. Such an application is firstly needed to move the smartphone camera from a research toward a clinical setting, as it enhances usability by non-technicians.” – by Phil Neuffer

Disclosures: The authors report no relevant financial disclosures. 

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