Biophotonics techniques are showing great potential for practical tissue diagnosis,
capable of localised optical spectroscopy as well as wide field imaging. Many of
those are generally based on the same concept: the spectral information they enable
to acquire encloses clues on the tissue biochemistry and biostructure and these
clues carry diagnostic information. Biophotonics techniques present the added
advantage to incorporate easily miniaturisable hardware allowing several modalities
to be set up on the same systems and authorizing their use during minimally invasive
surgery (MIS) procedures. The work presented in this thesis aims to build on these
advantages to design biophotonics instruments for tissue diagnosis. Fluorescence
and diffuse reflectance, the two modalities of interest in this work, were implemented
in their single point spectroscopic and imaging declinations. Two “platforms”, a
spectroscopic probe setup and an optical imaging laparoscope, were built; they
included either one of the two aforementioned modalities or the two of them together.
The spectroscopic probe system was assembled to detect lesions in the
digestive tract. In its first version, the setup included a dual laser illumination system
to carry out an ex vivo fluorescence study of non-alcoholic fatty liver diseases
(NAFLD) in the mouse model. Outcomes of the study demonstrated that healthy
livers could be distinguished from NAFLD livers with high classification accuracy.
Then, the same fluorescence probe inserted in a force adaptive robotic endoscope
was applied on a fluorescence phantom and a liver specimen to prove the feasibility
of recording spectra at multiple points with controlled scanning pattern and
probe/sample pressure (known to affect the spectra shape). This approach proposed
therefore a convincing method to perform intraoperative fluorescence measurements.
The fluorescence setup was subsequently modified into a combined
fluorescence/diffuse reflectance spectroscopic probe and demonstrated as an
efficient method to separate normal and diseased tissue samples from the human
gastrointestinal tract.
Following the single point spectroscopy work, imaging studies were
conducted with a spectrally resolved laparoscope. The system, featuring a CCD/filter
wheel unit clipped on a traditional laparoscope was validated on fluorescence
phantoms and employed in two experiments. The first one, building on the spectroscopy study of the gastrointestinal tract,
was originally aimed at locating tumour in the oesophagus but a lack of tissue
availability prevented us from doing so. The system design and validation on
fluorophores phantoms were nevertheless described. In the second one, the
underarm of a pig was imaged after injection of a nerve contrast agent in order to test
the feasibility of in vivo nerve delineation. Fluorescence was detected from the region
of interest but no clear contrast between the nerve and the surrounding muscle tissue
could be detected. Finally, the fluorescence imaging laparoscope was modified into a
hyperspectral reflectance imaging laparoscope to perform tissue vasculature studies.
It was first characterized and tested on haemoglobin phantoms with varying
concentrations and oxygen saturations and then employed in vivo to follow the
haemoglobin concentration and oxygen saturation temporal evolutions of a porcine
intestine subsequently to the pig’s termination. A decrease in oxygen saturation was
observed. The last experiment consisted in monitoring the tissue re-oxygenation of a
rabbit uterus transplant on the recipient animal, a successful tissue re-perfusion after
the graft was highlighted.