Multispectral Tissue Analysis
Pathological structures, e.g. tumors, can develop between or in the direct proximity to important structures, for example nerves. During surgery, it is hard to differentiate the various tissue types. Currently, this continuous differentiation is based on the surgeon’s knowledge only. A visualization of important tissue structures would allow the surgeon to perform operations faster and with less risk of patient damage. However, automatic methods based on optical in vivo properties of human tissue do not yet exist, as these properties have not been sufficiently examined. To overcome this, we develop and investigate several hyperspectral camera setups to monitor the different optical behavior of tissue types in vivo, as preoperative screening and tissue localization cannot be used to achieve a robust differentiation during surgery.
The first focus in multispectral tissue analysis is on ear, nose throat (ENT) surgery. In a first step, relevant tissue types has been extracted during surgical standard procedures and examined in a spectrophotometer to obtain the optical tissue properties of fresh tissue samples. Additionally, the same tissue types are analyzed with different optical camera-illumination setups.
Setup
We will investigate three different setups for the tissue analysis:
- Hyperspectral Snapshot Camera and scene illumination with spectrally-broadband, visible-wavelength light (white light)
- Monochromatic Camera and scene illumination with different narrowband light sources
- RGB Camera and scene illumination with different broader narrowband light sources
Building an HSI-based computer-aided tissue analysis system requires accurate ground truth and validation of optical soft tissue properties as these show large variability. Therefore, the setups are calibrated and validated using the same database and calibration set. For validation, a color chart with 18 well-defined color spectra in the visual range is analyzed. Thus, the results acquired with all settings become transferable and comparable to each other as well as between different interventions.
Visualization
Further, we develop techniquesways to appropriatley visualize the extracted multispectral tissue information in a microscope or endoscope, e.g. by enhancing the reconstructed data in the relevant spectral range (e.g. 460 nm to 480 nm for nerve, see image).
Example for the enhancement of nerve tissue
Publications
E. Wisotzky, P. Arens, S. Dommerich, A. Hilsmann, P. Eisert, F. Uecker, Determination of optical properties of cholesteatoma in the spectral range of 250 to 800 nm, Biomedical Optics Express, 11(3), 2020.
E. Wisotzky, F. C. Uecker, S. Dommerich, A. Hilsmann, P. Eisert, P. Arens, Determination of optical properties of human tissues obtained from parotidectomy in the spectral range of 250 to 800 nm, Journal of Biomedical Optics, 24(12):125001, 2019.
E. Wisotzky, B. Kossack, F. C. Uecker, P. Arens, S. Dommerich, A. Hilsmann, P. Eisert, Validation of two techniques for intraoperative hyperspectral human tissue determination, Proc. of SPIE, 10951:109511Z, 2019.
E. Wisotzky, F. Uecker, P. Arens, S. Dommerich, A. Hilsmann, P. Eisert, Intraoperative hyperspectral determination of human tissue properties, Journal of Biomedical Optics, 23(9):091409, 2018. [PDF]