Dual imaging of arterial walls: intravascular ultrasound and fluorescence spectroscopy

This paper describes a combined ultrasonic and spectroscopic system for imaging both the structure and chemical composition of atherosclerotic plaque. Using this system, ultrasound pulse echo distance estimations can be used to accurately compensate detected tissue fluorescence intensities for a wide range of tissue-detector separations, D. Compensation is achieved using an empirical model, wherein fluorescence intensity decreases as 1/Dn with n equals 1.1 for tissue detector separations from 2.5 to 5 mm and 1.4 for separations of 5 to 15 mm. This behavior indicates that fluorescence exiting the tissue surface is not isotropic.