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Owing to its superior resolution, intravascular optical coherence tomography (IVOCT) is a promising tool for imaging the microstructure of coronary artery walls. However, IVOCT does not identify chemicals and molecules in the tissue, which is required for a more complete understanding and accurate diagnosis of coronary disease. Here we present a dual-modality imaging system and catheter that uniquely combines IVOCT with diffuse near-infrared spectroscopy (NIRS) in a single dual-modality imaging device for simultaneous acquisition of microstructural and compositional information. As a proof-of-concept demonstration, the device has been used to visualize co-incident microstructural and spectroscopic information obtained from a diseased cadaver human coronary artery.

We demonstrate a fluorescence spectrometer that utilizes principles of Fourier transform spectroscopy to measure excitation emission matrices (EEM) rapidly and with high spectral resolution. For this EEM fluorometer, incoherent excitation light is first input into a differential-delay scanning Michelson interferometer. Light from the output port excites sample fluorescence. The fluorescence remitted from the sample is directed to a second Michelson interferometer, whose differential-delay scanning is synchronized with the first interferometer. The EEM is obtained by two-dimensional Fourier analysis of the detected signal from the output port of the second interferometer. EEM results from the system are verified by comparing with results from a standard spectrometer. The system provides a wide spectral range, adjustable spectral resolution, and fast EEM acquisition speed, which allows EEM's to be acquired in 40 seconds at a spectral resolution of 81-cm-1.