Identification of tumor margins using diffuse reflectance spectroscopy with an extended-wavelength spectrum in a porcine model.

OBJECTIVE: A novel extended-wavelength diffuse reflectance spectroscopy (EWDRS) technique is being developed for future clinical non-invasive tumor margin delineation. In this study, the ability of EWDRS to identify the margins of pigmented skin lesions in an in vivo pig model was evaluated. MATERIALS AND METHODS: Extended-wavelength diffuse reflectance spectroscopy recordings (350-1550 nm) were made on 13 pigmented skin lesions and non-pigmented skin, as a reference. The hand-held probe was swept toward the pigmented area until the signal changed, thus indicating that the margin had been identified. A needle was inserted as a marker, and tissue samples were sent for histological analysis. The distance between the EWDRS-defined border and the histological border was measured by 3 independent examiners. RESULTS: The median difference between the EWDRS-defined border and the histological border was 70 µm toward the pigmented tissue (range: -579 to 538 µm). A Pearson correlation coefficient of .95 was obtained for the examiners. CONCLUSIONS: Extended-wavelength diffuse reflectance spectroscopy can be used in vivo to delineate the border of pigmented skin lesions in a porcine model with high accuracy, indicating that it may be a useful tool for non-invasive tumor margin delineation in the future.

Cavity enhanced absorption spectroscopy of multiple trace gas species using a supercontinuum radiation source.

Supercontinuum radiation sources are attractive for spectroscopic applications owing to their broad wavelength coverage, which enables spectral signatures of multiple species to be detected simultaneously. Here we report the first use of a supercontinuum radiation source for broadband trace gas detection using a cavity enhanced absorption technique. Spectra were recorded at bandwidths of up to 100 nm, encompassing multiple absorption bands of H(2)O, O(2) and O(2)-O(2). The same instrument was also used to make quantitative measurements of NO(2) and NO(3). For NO(3) a detection limit of 3 parts-per-trillion in 2 s was achieved, which corresponds to an effective 3sigma sensitivity of 2.4 x 10(-9) cm(-1)Hz(-1/2). Our results demonstrate that a conceptually simple and robust instrument is capable of highly sensitive broadband absorption measurements.