Calibration and test of a hyperspectral imaging prototype for intra-operative surgical assistance

A significant recent breakthrough in medical imaging is the development of a new non-invasive modality based on multispectral and hyperspectral imaging that can be easily integrated in the operating room. This technology consists of collecting series of images at wavelength intervals of only few nanometers and in which single pixels have spectral information content relevant to the scene under observation. Before becoming of practical interest for the clinician, such system should meet important requirements. Firstly, it should enable real reflectance measurements and high quality images to dispose of valuable physical data after spatial and spectral calibration. Secondly, quick band pass scanning and a smart interface are needed for intra-operative mode. Finally, experimentation is required to develop expert knowledge for hyperspectral image interpretation and result display on RGB screens, to assist the surgeon with tissue detection and diagnostic capabilities during an intervention. This paper is focused mainly on the two first specifications of this methodology applied to a liquid crystal tunable filter (LCTF) based visible and near infrared spectral imaging system. The system consists of an illumination unit and a spectral imager that includes a monochrome camera, two LCTFs and a fixed focal lens. It also involves a computer with the data acquisition software. The system can capture hyperspectral images in the spectral range of 400 - 1100 nm. Results of preclinical experiments indicated that anatomical tissues can be distinguished especially in near infrared bands. This promises a great capability of hyperspectral imaging to bring efficient assistance for surgeons.