In Vivo Optical Imaging of Fluorescent Markers for Detection and Guided Resection of Cancer

Fluorescent molecules, hereafter referred to as fluorophores, can be excited by illumination with light and subsequently can de-excite into the ground state through, amongst others possibilities, emission of fluorescence. In case the fluorophore is selectively taken up by the cancer and not by surrounding normal tissues the fluorescence may thus be used for the detection and localization of cancers. The research described in this thesis focuses on the development of methods and technology for real-time in vivo fluorescence imaging for cancer detection and image-guided surgical tumor resection. Subsequently, the introduced methods and technology are evaluated through modelling studies and validated with pre-clinical experiments and clinical trials in patients. After a general introduction in Chapter 1, Chapter 2 describes the development of a fluorescence imaging device for the detection of superficial cancer based on the Double Ratio technique. In practical use this device resembles an operation microscope and can be used in a clinical environment. This device acquires 4 different fluorescence images excited at two wavelengths each detected at two wavelengths. From these images it calculates, displays and stores Double Ratio images at a maximum speed of 1Hz. The Double Ratio image gives the distribution of the fluorophore amount present in tissue and is not affected by local variations in tissue optics, i.e. tissue absorption and tissue scattering. The validity of the technique was confirmed here by ex vivo tissue equivalent phantom experiments using hematoporphyrin and in vivo experiments on normal pigmented moles on Caucasian human skin using aminolevulinic acid In Chapter 3 we investigated if the device described in Chapter 2 could be used as an imaging technique for the diagnoses of cervical intraepithelial neoplasia (CIN) in patients.