In order to position for example a needle under image guidance more accurately in a suspicious tissue, tissue sensing at the tip of the device may be of interest. Current needles often do not have such tissue feedback possibilities. Recently, elongated interventional devices have been reported with optical fibers integrated into the device which provide feedback from the tissue at the tip of the device. Such devices allow for fine-guidance towards small volumes of suspicious tissue, in particular for tissue which does not show sufficient contrast in imaging. In order to allow tissue discrimination, these devices employ diffuse reflectance spectroscopy (DRS).
A so called photonic needle allows for determining tissue type by sending light with a broadband spectrum into the body through one or more illumination fibers and measuring the reflected spectrum and determining the type of tissue by the application of an algorithm on this spectrum through one or more collection fibers. This is a diffuse reflectance measurement that may be obtained by normalizing the measured tissue spectrum with a previously measured reference spectrum. This requires either frequent calibration with a reference spectrum which is cumbersome in the workflow in a hospital, or piece-wise calibration together with a very tight control over the stability of all components in the optical path resulting in high cost and a constraint to large core fibers making the use of smaller needles than G21 not feasible.