On the Feasibility of Skin Water Content Imaging Adjuvant to Tissue Oximetry

Oxygen supply to tissues can be seriously impacted during wound healing. In particular, edema can increase the distance between capillaries, thus decreasing oxygen supply to cells. Thus, the detection of edema, preferably at the preclinical stage, is of great importance. However, there is no reference standard for a cross-sectional, objective measurement of edema. Multispectral imaging can be such adjuvant technology to elucidate the impact of edema on oxygen transport to tissues. The purpose of the current study is to assess the feasibility of multispectral imaging for visualization of water content in surface tissues.

The skin (hand and forearm) of healthy volunteers was imaged using the Multi-Spectral Imaging Device (MSID). MSID is a multispectral imaging system for visualization of tissue chromophores in surface tissues. It uses a 12-bit scientific-grade NIR-enhanced monochrome camera and ten wavelength light source (600-1000 nm range) to visualize the distribution of oxy- and deoxyhemoglobins, methemoglobin, water, and melanin. The imaging distance is 30 cm and the field of view: 7 × 7 cm.

Water content was extracted using various subsets of two and three wavelengths. To mimic the use of a consumer-grade camera, four least significant bits for each pixel value of a 12-bit image were discarded during preprocessing. Eight-bit results were compared with 12-bit results.

Rough numerical calculations and initial experiments show feasibility of water content imaging in the skin using 970 nm band illumination and 12- and 8-bit cameras.