Comparative Quantification of Arterial Lipid by Intravascular Photoacoustic-Ultrasound Imaging and Near-Infrared Spectroscopy-Intravascular Ultrasound

Abstract

Intravascular photoacoustic-ultrasound (IVPA-US) imaging and near-infrared spectroscopy-intravascular ultrasound (NIRS-IVUS) are two hybrid modalities that detect arterial lipid, with comparison necessary to understand the relative advantages of each. We performed in vivo and ex vivo IVPA-US imaging of the iliac arteries of Ossabaw swine with metabolic syndrome (MetS) and lean swine to investigate sensitivity for early-stage atherosclerosis. We repeated imaging ex vivo with NIRS-IVUS for comparison to IVPA-US and histology. Both modalities showed significantly greater lipid in MetS vs. lean swine, but only IVPA-US localized the lipid as perivascular. To investigate late-stage atherosclerosis, we performed ex vivo IVPA-US imaging of a human coronary artery with comparison to NIRS-IVUS and histology. Two advanced fibroatheromas were identified, with agreement between IVPA-measured lipid area and NIRS-derived lipid content. As confirmed histologically, IVPA-US has sensitivity to detect lipid content similar to NIRS-IVUS and provides additional depth resolution, enabling quantification and localization of lipid cores within plaques. Electronic supplementary material The online version of this article (10.1007/s12265-018-9849-2) contains supplementary material, which is available to authorized users.

Highly sensitive lipid detection and localization in atherosclerotic plaque with a dual‐frequency intravascular photoacoustic/ultrasound catheter

“…We showed previously that we were able to quantify and localize the lipid in these lipid core lesions using IVPA/US, but not with near‐infrared spectroscopy coupled with IVUS. [ 21 ]…”

“…We showed previously that we were able to quantify and localize the lipid in these lipid core lesions using IVPA/US, but not with near-infrared spectroscopy coupled with IVUS. [21] More imaging results at different locations of the artery were displayed in Figure 6 to show different plaque types of the pig artery. It reveals that plaques with intima thickening (region between blue and green profiles) from moderate level (II) to advanced levels (I, III, IV) of plaque burden were observed in this piece of artery, and mixed fibrous/calcified plaque (III) was also identified from the shadowed region denoted by a yellow double arrow line in the ultrasound image.…”

Perivascular Adipose Tissue as an Indication, Contributor to, and Therapeutic Target for Atherosclerosis

“…Carotid EMT is a promising index for early assessment of the clinical risk of atherosclerosis (Skilton, 2019). Similarly, intravascular photoacoustic ultrasound detected increased iliac arteries-PVAT in Ossabaw swine with metabolic syndrome, which was verified by histology as early-stage atherosclerotic changes (Kole et al, 2019).…”

“Light in and Sound Out”: Review of Photoacoustic Imaging in Cardiovascular Medicine

“…During IVPA imaging, atherosclerotic plaques are visualized according to different optical absorption characteristics of various tissue components ( Figure. 2) [16]. In a recent study, IVPA was shown to be comparable with Near-Infrared Spectroscopy (NIRS) in its sensitivity to quantify and localize lipid within atherosclerotic plaques, yet at the same time provides additional depth resolution, for which NIRS itself is deficient [17]. A brief summary comparing two intravascular imaging techniques currently in clinical use with PAI is shown in Table 1.…”