Intraluminal fluorescence spectroscopy catheter with ultrasound guidance

Abstract

We demonstrate the feasibility of a time-resolved fluorescence spectroscopy (TRFS) technique for intraluminal investigation of arterial vessel composition under intravascular ultrasound (IVUS) guidance. A prototype 1.8-mm (5.4 Fr) catheter combining a side-viewing optical fiber (SVOF) and an IVUS catheter was constructed and tested with in vitro vessel phantoms. The prototype catheter can locate a fluorophore in the phantom vessel wall, steer the SVOF in place, perform blood flushing under flow conditions, and acquire high-quality TRFS data using 337-nm wavelength excitation. The catheter steering capability used for the coregistration of the IVUS image plane and the SVOF beam produce a guiding precision to an arterial phantom wall site location of 0.53±0.16 mm. This new intravascular multimodal catheter enables the potential for in vivo arterial plaque composition identification using TRFS.

Design, construction, and validation of a rotary multifunctional intravascular diagnostic catheter combining multispectral fluorescence lifetime imaging and intravascular ultrasound

“…Such catheter system is expected to provide a more effective means for the characterization of arterial wall pathologies. The current study extends on our previous work that demonstrated the potential use of TRFS combined with IVUS to obtain complementary information using a fixed orientation multimodal catheter 16 and the ability of scanning-TRFS to reconstruct FLIm images of luminal surfaces. 11 A critical issue in bringing TRFS systems closer to clinical application, concerns the ability of the system to acquire robust TRFS data in intraluminal setting radially and continuously from the vessel wall in blood flow similarly and simultaneously with IVUS.…”

Fluorescence lifetime imaging for the characterization of the biochemical composition of atherosclerotic plaques

“…This is important because in an intravascular implementation, the fluorescence intensity is affected by the presence of blood and likely changes of optical excitation-collection geometry, whereas time-resolved parameters are relatively independent of such factors. 21,22 All of these attributes suggest the potential of an intravascular implementation of this FLIM system for the study and diagnosis of atherosclerosis in a clinical setting.…”

“…These results are being used to develop a more clinically robust system that employs a TRFS system in a scanning mode to create intravascular FLIM images. 17 In previous studies, 16,21,22 we showed that such a TRFS technique allows for faster data acquisition, a 10-fold increase in temporal resolution, and a lower energy delivery level compared to the whole-field FLIM technique described here. Moreover, we demonstrated the luminal application of TRFS via a side-viewing fiber in phantoms and porcine models.…”

“…As previously stated, this group could potentially be considered pathologic intimal thickening, which is the first sign of atherosclerosis, different from nonatherosclerotic plaque formation that occurs in the form of fatty streaks in humans as early as childhood. 21 It could also be considered intimal xanthoma. 33 This discrimination allows for the idea that fluorescence lifetime could be a useful tool in studying preclinical atherosclerosis to aid in the research being done to identify what causes a plaque to become atherosclerotic, and in particular, what causes a plaque to become vulnerable to rupture.…”

“…Moreover, we demonstrated the luminal application of TRFS via a side-viewing fiber in phantoms and porcine models. 21,22 Although, in this study the ROIs were hand-selected based on histopathology, which would not be ideal for a clinical diagnostic tool. We envision that the future availability of a larger dataset can enable development of an algorithm designed to automatically segment FLIM images into ER, E+M, CR, and LR ROIs as can be deduced by the preliminary linear discriminant classification results presented here.…”