Multimodal Imaging for Tissue Assessment

The fiberoptic DRS system consisted of a Tungsten halogen broadband light source and two spectrometers; one for the visible domain (400–1100 nm, Andor Technology, DU420ABRDD) and one for the infrared domain (900–1700 nm, Andor Technology, DU492A-1.7)^{48 (link)}. A probe with two source-detector fiber distances of 2 and 6 mm was used to retrieve information from both superficial and deeper sampling depths. In DRS, the sampling depth (penetration depth of the detected photons) depends on the distance between the source and detector fiber. Even though the sampling depth is also influenced by the sample optical properties, it has been shown that the sampling depth is approximately equal to the source-detector distance^{49 (link)}. Ultrasound images were acquired using the portable Philips CX50 machine (Philips Research, Eindhoven, The Netherlands) in combination with the Philips L15-7io transducer (Philips Research, Eindhoven, The Netherlands), a high-frequency 15–7 MHz ultrasound transducer specially designed for superficial imaging.