THE USE OF TIME-RESOLVED FLUORESCENCE FOR DIAGNOSIS OF ATHEROSCLEROTIC PLAQUE AND MALIGNANT-TUMORS

Time-resolved fluorescence was studied for two different applications: demarcation of malignant tumours from normal tissue and atherosclerotic plaque of different degrees from normal vessel wall. The time-correlated single-photon counting technique was employed using the second harmonic of a synchronously pumped argon-ion dyel/laser system. The time response of the detection system was approximately 70 ps. The results revealed a fluorescence band peaking at 380 nm with a lifetime of {reversed tilde equals}7 ns specific for atherosclerotic plaque. In this paper we discuss the importance of blood interference in spectroscopic data from vessels and how this can be avoided for a reliable diagnosis. We also present recordings on malignant tumours following systemic injection of Photofrin II. This tumour seeking drug has an effective fluorescence lifetime of {reversed tilde equals}15 ns allowing background-free recordings if delayed detection is used to suppress the more short-lived autofluorescence. © 1990.