Hyperspectral Imaging and Classification for Grading Skin Erythema

Abstract

Erythema is an inflammatory condition of the skin that is commonly used as a feature to monitor the progression of cutaneous diseases or treatment induced side effects. In radiation therapy, skin erythema is routinely assessed visually by an expert using standardized grading criteria. However, visual assessment (VA) is subjective and commonly used grading tools are too coarse to score the onset of erythema. Therefore, an objective method capable of quantitatively grading early erythema changes may help identify patients at higher risk for developing severe radiation induced skin toxicities. The purpose of this study is to investigate the feasibility of using hyperspectral imaging (HSI) for quantitative assessment of early erythema and to characterize its performance against VA documented on conventional digital photographic red-green-blue (RGB) images. Erythema was induced artificially on 3 volunteers in a controlled pilot study; and was subsequently measured using HSI and color imaging. HSI and color imaging data was analyzed using linear discriminant analysis (LDA) to perform classification. The classification results, including accuracy, and precision, demonstrated that HSI is superior to color imaging in skin erythema assessment.

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

“…For the intra-rater reliability, the following parameters were reported: intraclass correlation coefficients (ICC) = 0.55-1.00 [8][9][10][11] and Fleiss' kappa (KF) = 0.69 [8]. The inter-rater reliability was, as expected, lower, with the reported ICC = 0.41-0.78 [8,12], KC = 0.18-0.51 [13], and KF = 0.71 [8] Various custom-made or commercial imaging or spectroscopic devices (e.g., Mexameter MX 18, Courage-Khazaka Electronic, Köln, Germany) tried to overcome the subjectivity of erythema evaluation [6,[14][15][16][17] by calculating an erythema index (EI), which is a ratio between those spectral or imaging components that correlate well with the skin redness. A quotient between the red and green colors is the most common since the skin pigment melanin has a smaller impact on these two channels.…”

“…Various custom-made or commercial imaging or spectroscopic devices (e.g., Mexameter MX 18, Courage-Khazaka Electronic, Köln, Germany) tried to overcome the subjectivity of erythema evaluation [ 6 , 14 , 15 , 16 , 17 ] by calculating an erythema index (EI), which is a ratio between those spectral or imaging components that correlate well with the skin redness. A quotient between the red and green colors is the most common since the skin pigment melanin has a smaller impact on these two channels.…”

Hyperspectral imaging and characterization of allergic contact dermatitis in the short‐wave infrared

“…Color visible images are often used for quantification of skin erythema. [ 25 ] We used a TEI derived from color visible images to quantify erythema. Figure 8 shows that FEI appears to be indistinguishable for the first 11 days, and after which, the signal appears to be decreased.…”

Hyperspectral imaging enabled by an unmodified smartphone for analyzing skin morphological features and monitoring hemodynamics

“…A number of hyperspectral imaging systems have been recently developed for the analysis of skin features. One of such uses monochromatic lasers or optical filters (either filter wheels or tunable filters) to provide specific spectral illumination and uses a single array detector to sequentially capture the tissue reflection images [6][7][8][9]. For example, Kim et al used LED to provide illumination in multispectral imaging [10].…”