Evaluation of Erythema Severity in Dermatoscopic Images of Canine Skin: Erythema Index Assessment and Image Sampling Reliability

Abstract

The regular monitoring of erythema, one of the most important skin lesions in atopic (allergic) dogs, is essential for successful anti-allergic therapy. The smartphone-based dermatoscopy enables a convenient way to acquire quality images of erythematous skin. However, the image sampling to evaluate erythema severity is still done manually, introducing result variability. In this study, we investigated the correlation between the most popular erythema indices (EIs) and dermatologists’ erythema perception, and we measured intra- and inter-rater variability of the currently-used manual image-sampling methods (ISMs). We showed that the EIBRG, based on all three RGB (red, green, and blue) channels, performed the best with an average Spearman coefficient of 0.75 and a typical absolute disagreement of less than 14% with the erythema assessed by clinicians. On the other hand, two image-sampling methods, based on either selecting specific pixels or small skin areas, performed similarly well. They achieved high intra- and inter-rater reliability with the intraclass correlation coefficient (ICC) and Krippendorff’s alpha well above 0.90. These results indicated that smartphone-based dermatoscopy could be a convenient and precise way to evaluate skin erythema severity. However, better outlined, or even automated ISMs, are likely to improve the intra- and inter-rater reliability in severe erythematous cases.

A utilização da dermatoscopia na Medicina Veterinária: Uma revisão sistemática de literatura

“…Foram encontrados 12 artigos, 5 (41,66%) sobre caninos, 4 (33,33%) sobre felinos e 3 (25%) sobre equinos. Estes trabalhos foram selecionados e revisados, sendo possível ter acesso na área de Medicina Veterinária, a trabalhos sobre dermatoscopia, com uso na avaliação da pele felina normal, dermatofitose felina e canina, padrão de alopecia em cães (Scarampella et al, 2015, Dong et al, 2016, Zanna et al, 2016, Scarampella et al, 2017, Scarampella & Roccabianca, 2018, avaliação de pele equina normal (Legnani et al, 2017, Tomich et al, 2017, Zniszczynska et al, 2021, malformações linfáticas dérmicas superficiais congênitas acrais em gatos (Legnani et al 2020) e descrição de padrão colorimétrico em cães com eritroderma (Cugmas & Struc, 2020, Cugmas et al, 2021.…”

Evaluation of native canine skin color by smartphone‐based dermatoscopy

“…The skin color was determined with the smartphone‐ and dermatoscope‐based optical system, described in our previous studies. 13 , 25 Briefly, the system alternately included two smartphones (P20 Pro and P30 Pro, Huawei, Shenzhen, China) with an attached dermatoscope DermLite DL1 basic (3Gen, Inc., San Juan Capistrano, CA, USA), which provided a circular 3.0 cm 2 sampling area. The acquired RGB data were transformed to the CIELAB color space based on the model trained on the ColorChecker Classic (X‐rite, Grand Rapids, MI, USA).…”

“…23 Additionally, dermatoscopebased colorimetry has been recently reported to reliably estimate the skin erythema (redness) in allergic dogs. 24,25 Since erythema is one of the most important clinical signs during allergic flares, objective skin color estimations could lead to more reliable patient monitoring and, consequently, to better clinical outcomes. 26 Unlike the well-studied human skin, the color of native canine skin is unknown.…”

“…Even today, the coat color affects the personality characteristics people attribute to dogs 23 . Additionally, dermatoscope‐based colorimetry has been recently reported to reliably estimate the skin erythema (redness) in allergic dogs 24,25 . Since erythema is one of the most important clinical signs during allergic flares, objective skin color estimations could lead to more reliable patient monitoring and, consequently, to better clinical outcomes 26 …”