The mechanism of most medical endoscopes is based on the interaction between light and biological tissue, inclusive of absorption, elastic scattering and fluorescence. In essence, the metrics of those interactions are obtained from the fundamental properties of light as an electro-magnetic waves, namely, the radiation intensity and wavelength. As another fundamental property of light, polarisation can not only reveal tissue scattering and absorption information from a different perspective, but is also able to provide a fresh insight into directional tissue birefringence properties induced by birefringent compositions and anisotropic fibrous structures, such as collagen, elastin, muscle fibre, etc at the same time. Here we demonstrate a low cost high definition Muller polarimetric endoscope with minimal alteration of a rigid endoscope. By imaging birefringent tissue mimicking phantoms and a porcine bladder, we show that this novel endoscopic imaging modality is able to provide different information of interest from unpolarised endoscopic imaging, including linear depolarization, circular depolarization, birefringence, optic axis orientation and dichroism. This endoscope can potentially be employed for better tissue visualisation and benefit endoscopic investigations and intra-operative guidance.
Nanoparticles are viewed as a promising tool for numerous medical applications, for instance imaging and
photothermal therapy (PTT) has been proposed using gold nanorods. We are developing multi-functional gold
nanorods (m-GNRs) which have potential for image guided endoscopic surgery of tumour tissue with a
modified laparoscope system. A new synthesis method potentially allows any useful acid functionalised
molecules to be bonded at the surface. We have created fluorescent m-GNRs which can be used for therapy as
they absorb light in the infrared, which may penetrate deep into the tissue and produce localised heating. We
have performed a tissue based experiment to demonstrate the feasibility of fluorescence guided PTT using m-
GNRs. Ex vivo tests were performed using sheep heart. This measurement, correlated with the fluorescence
signal of the m-GNRs measured by the laparoscope allows the clear discrimination of the artery system
containing m-GNRs. A laser diode was used to heat the m-GNRs and a thermal camera was able to record the
heat distribution. These images were compared to the fluorescence images for validation.
A multi-spectral illumination approach for real-time mapping of the presence of gold nanoparticles in bulk tissue
is presented. A Principal Component Analysis method is followed for determining the wavelengths that will
make up the multispectral imaging endoscope.
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