Validating a bimodal intravascular ultrasound (IVUS) and near-infrared fluorescence (NIRF) catheter for atherosclerotic plaque detection in rabbits

Abstract

Coronary artery disease is characterized by atherosclerotic plaque formation. Despite impressive advances in intravascular imaging modalities, in vivo molecular plaque characterization remains challenging, and different multimodality imaging systems have been proposed. We validated an engineered bimodal intravascular ultrasound imaging (IVUS) / near-infrared fluorescence (NIRF) imaging catheter in vivo using a balloon injury atherosclerosis rabbit model. Rabbit aortas and right iliac arteries were scanned in vivo after indocyanine green (ICG) injection, and compared to corresponding ex vivo fluorescence and white light images. Areas of ICG accumulation were colocalized with macroscopic atherosclerotic plaque formation. In vivo imaging was performed with the bimodal catheter integrating ICG-induced fluorescence signals into cross-sectional IVUS imaging. In vivo ICG accumulation corresponded to ex vivo fluorescence signal intensity and IVUS identified plaques.

Validating Intravascular Imaging with Serial Optical Coherence Tomography and Confocal Fluorescence Microscopy

“…White arrows indicate colocalization between in vivo and ex vivo fluorescence. Arrow 3 shows a weaker colocalization due to the limitation of our blood attenuation compensation algorithm [19], further supporting the need for co-registered ex vivo validation.…”

“…Multimodality imaging systems, such as the dual-modality IVUS/near-infrared fluorescence (NIRF) imaging catheter previously engineered by our group and others [10,11,12,13], were designed for integrated microstructural and molecular plaque imaging, thus enabling a more detailed plaque characterization. The use of molecular probes in conjunction with fluorescence imaging has been shown to provide complementary information with regards to plaque activity and inflammation [14,15,16,17,18,19]. Translation of molecular imaging results to clinical applications, however, requires validation; and despite impressive advances in intravascular imaging over the past decade, histology remains the gold standard for determining plaque composition and geometry.…”

Multimodal intravascular imaging technology for characterization of atherosclerosis

“…These systems, including IVUS-NIRF, IVUS-NIRS, IVUS-FLIM (°uorescence-lifetime imaging microscopy), are able to visualize the entire structure and composition of coronary artery simultaneously. 24,[60][61][62][63] Among them, IVUS-NIRS has been commercialized and approved for clinical use in the United States. Similar to IVOCT-NIRF, the lack of depth-resolved molecular contrast limits their accuracy, and the penetration depth of the optical imaging may not be su±cient to cover the entire region of interest, especially for FLIM.…”

Invasive or non-invasive imaging for detecting high-risk coronary lesions?

“…Two studies compared the plaque burden estimations of black-blood MRI and IVUS and the first showed a good correlation between MRI and IVUS estimations while in the other report, there was a weak association between MRI and IVUS [110,111]. [62] and Abran et al [84]. Full color available online.…”