Hyperspectral analysis of tissue damage

UV-VIS hyperspectral data of kidney arteria of a pig
UV-VIS hyperspectral data of kidney arteria of a pig

The spectral analysis of tissue provides important information regarding biological functions. Such information cannot be easily extracted from classic color images.

For example, in the visible wavelength range, measuring the absorption bands gives access to the concentration of hemoglobin and the blood ratio of oxy/deoxyhemoglobin. Hence, the LLA UV-VIS hyperspectral camera uniSPEC0.9HSI provides a quick and non-invasive diagnostic of the healt of tissue and organs.

Tissue/ skin analysis

NIR hyperspectral data of a finger showing different features of interest located on separate spectral bands
NIR hyperspectral data of a finger showing different features of interest located on separate spectral bands

Spectral analysis of living tissue can provide information regarding its important biological functions. Absorption features in the visible spectral range are utilised for the determination of haemoglobin concentration and the ratio of oxygenated and deoxygenated haemoglobins in blood. In the NIR range, the moisture content on skin level can be spectrally measured.

However, most of these analyses are utilising single spot measurement systems which do not provide the spatial distribution of the investigated parameter in the living tissue. Systematic changes in large samples or in body parts are therefore not accessible. Even in combination with sampling systems e.g. motor driven y-x stages, the sampling times can become very high, leading to a potential deterioration of the tissue/ skin sample due to its exposure to NIR radiation.

NIR hyperspectral imaging systems such as uniSPEC1.7HSI can be utilised to scan the full tissue sample in a short time, minimising deterioration effects due to the heat generated by the NIR radiation. In addition to the spatial distribution of biological parameters, geometrical analysis of skin features at high spatial resolution becomes feasible. The combination of high resolution spectral and geometrical analysis of liver spots has great potential as non-invasive and rapid method for diagnostics of skin cancer at an early stage.

Example: NIR hyperspectral data of a hand

(working in the 1090nm-1100nm band allows a sub-cutaneous non-invasive insight of the blood vessels)

Camera picture NIR-identification

Monitoring of plants for agriculture and forestry

Hyperspectral analysis of leaves (relative chlorophyll contents)
Hyperspectral analysis of leaves (relative chlorophyll contents)

The VIS spectral analysis of plants can provide information regarding chlorophyll concentration as well as chlorophyll type, carotenoid or anthocyanin concentration. These concentrations can be related to important plant physiological parameters which are utilised in agriculture as an important tool for crop monitoring. These parameters can be related to plant health, crop yield, vegetation stress indication and many more.

For large scale monitoring, satellite data is utilised as fundament for the determination of physiological parameters and vegetation indices (VI). However, the satellite data usually provide a small number of spectral bands, limiting the number of available vegetation indices. More accurate study of vegetation requires the use of so-called narrowband VI, which can only be provided by the use of high spectral resolution systems. For smaller scale monitoring, VIS laboratory spectrometers do provide a full spectral resolution, but a spatial distribution of a parameter in a plant may not be investigated.

The VIS hyperspectral imaging camera uniSPEC0.9HSI provides full spectral resolution in combination with a high scanning speed and a high spatial resolution. This enables the characterisation of plants in large scale utilising a large number of vegetation indices on a single dataset. On a smaller scale, the spatial resolution enables the monitoring of the distribution of important physiological parameters in a plant.

The picture is providing the hyperspectral analysis of leaves. It is possible to spectrally separate the signal of chlorophyll from the pigments, and to quantify the chlorophyll contents, hence providing important information regarding the health of the sample.

Fluorescence-based microscopy

On a smaller spatial scale, hyperspectral cameras have a high potential in the field of fluorescence-based light microscopy. The acquisition of the full broad-range spectrum of a sample is extremely advantageous when it comes to the use of environment-sensitive markers (for example pH-sensitive fluorescence probes), or when the sample displays strong self-fluorescence background (in which case techniques like spectral unmixing are required).

With common spectroscopic microscopy systems, the acquisition of a high resolution spectrum requires a large amount of time, making absolute stability of the system a strong requirement, or leading to bleaching of the fluorescent marker. Using a hyperspectral camera as a detector allows acquiring the full spectrum of a sample line in just one frame, hence drastically reducing the time of acquisition and reducing the light damage on the sample.