Multispectral imaging system based on light-emitting diodes for the detection of melanomas and basal cell carcinomas: a pilot study

Abstract

This article proposes a multispectral system that uses the analysis of the spatial distribution of color and spectral features to improve the detection of skin cancer lesions, specifically melanomas and basal cell carcinomas. The system consists of a digital camera and light-emitting diodes of eight different wavelengths (414 to 995 nm). The parameters based on spectral features of the lesions such as reflectance and color, as well as others empirically computed using reflectance values, were calculated pixel-by-pixel from the images obtained. Statistical descriptors were calculated for every segmented lesion [mean ( x ˜ ), standard deviation ( σ ), minimum, and maximum]; descriptors based on the first-order statistics of the histogram [entropy ( E p ), energy ( E n ), and third central moment ( μ 3 )] were also obtained. The study analyzed 429 pigmented and nonpigmented lesions: 290 nevi and 139 malignant (95 melanomas and 44 basal cell carcinomas), which were split into training and validation sets. Fifteen parameters were found to provide the best sensitivity (87.2% melanomas and 100% basal cell carcinomas) and specificity (54.5%). The results suggest that the extraction of textural information can contribute to the diagnosis of melanomas and basal cell carcinomas as a supporting tool to dermoscopy and confocal microscopy.

Morphological study of skin cancer lesions through a 3D scanner based on fringe projection and machine learning

“…Other methods such as multispectral imaging systems, which acquire images at different wavelengths, have also been used to detect skin cancer. Comparing the 3D results with those obtained in a previous study where a multispectral imaging system from 414 nm to 995 nm was applied to the study of skin cancer [6], our results show significantly increased specificity at the only expense of a slightly lower sensitivity. The authors obtained sensitivity and specificity of 87.2% and 54.5%, respectively, for a 50%-50% validation scheme with a customized classification algorithm in a set of 502 lesions (nevi, melanomas and basal cell carcinomas).…”

“…Some authors have tried to detect skin cancer quantitatively and non-invasively through optical devices. Confocal microcopy [4], optical coherence tomography [5] and multispectral imaging [6,7] are among the most commonly used imaging modalities. Three-dimensional (3D) technology can also be used to retrieve topographic information of cutaneous lesions, producing a height map of the lesion's surface from which parameters of area, volume and texture can be calculated.…”

Fast visible and extended near-infrared multispectral fundus camera

“…Ocular fundus, reference white, and dark current images were captured using the same exposure times for each spectral band ( Table 1). The reflectance was then calculated as commonly described in the literature: 9,10,26 E Q -T A R G E T ; t e m p : i n t r a l i n k -; e 0 0 1 ; is the calibrated reflectance of the reference white given by the manufacturer. Despite the fact that we use the term reflectance in accordance with other spectroscopic applications, it is noteworthy that Refl λn also includes the transmission of the ocular media (cornea, lens, aqueous humor, and vitreous) besides the reflectance of the retina itself.…”

“…Multispectral imaging (MSI) technology, which increases the amount of extractable spectral information from biological tissues using more than three spectral bands, has been used in the last few years to advance the diagnosis of many diseases. [7][8][9][10] Newly developed fundus cameras that include MSI hold great promise for the analysis of the retina, since they combine the usefulness of spectroscopy with imaging, thus providing both spectral and spatial information of retinal landmarks. For instance, they can spotlight vascular occlusions, vein hemorrhages, drusen, and exudates, and also build oxygenation maps of the retinal vasculature, contributing in this way to the early diagnosis and treatment of conditions such as age-related macular degeneration (AMD) and diabetic retinopathy.…”

“…Since the LEDs do not work with a closed-loop intensity control, periodic calibrations of the system must be carried out to guarantee an accurate retrieval of the spectral features of the retina at all wavelengths along all LEDs lifecycle. 9 Finally, after the light hazard protection evaluation, the MSI camera was classified as group 1 (nonhazardous ophthalmic instrument).…”