Sentinel lymph node detection by optical methods using scattered and fluorescence photons
TELLIER, Franklin Gérard Francis
Sentinel lymph node detection by optical methods using scattered and fluorescence photons.
Thèses de doctorat,
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The sentinel lymph node (SLN) method has become the gold standard to detect breast cancer metastasis. Two optical methods of detection and localization of SLN have been implemented. The first is based on the recording of scattered photons in the tissue to detect dye accumulated in the node. The second consists in detecting the emission of fluorescence photons. For both applications the dye selected is the most frequently used in clinical routine: Patent Blue V (PBV). A first optical instrument has been developed, using 4 excitation laser diodes, to discriminate absorption of PBV from that of other tissue chromophores, and one photodiode of detection. Experiments on solutions simulating the optical properties of breast tissue determined that the probe was 30 times more sensitive than the eye. Animal experimentation allowed to verify, in-vivo, the feasibility of the method. Subsequent collaboration with a regional cancer centre has permitted ex-vivo characterization of the prototype using 78 surgical pieces marked with low volumes of PBV and not visually blue. Our parallel studies highlighted an enhancement of the PBV fluorescence quantum yield by a factor of 30 when it was bounded to human serum albumin. Thus, a prototype to detect fluorescence photons has been developed. Its detection threshold is 100 times as low as that of the human eye. Fluorophore-marked nodes were detected in an animal model, with this device and using an appropriate imaging system. This device can localize precisely a marked SLN after percutaneous injection of a fluorescent dye.
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