Specific imaging of atherosclerotic plaque lipids with two-wavelength intravascular photoacoustics

Abstract

Abstract:The lipid content in plaques is an important marker for identifying atherosclerotic lesions and disease states. Intravascular photoacoustic (IVPA) imaging can be used to visualize lipids in the artery. In this study, we further investigated lipid detection in the 1.7-µm spectral range. By exploiting the relative difference between the IVPA signal strengths at 1718 and 1734 nm, we could successfully detect and differentiate between the plaque lipids and peri-adventitial fat in human coronary arteries ex vivo. Our study demonstrates that IVPA imaging can positively identify atherosclerotic plaques using only two wavelengths, which could enable rapid data acquisition in vivo. References and links1. E. Falk, P. K. Shah, and V. Fuster, "Coronary Plaque Disruption," Circulation 92(3), 657-671 (1995 Caplan, A. P. Burke, R. Virmani, J. Goldstein, and J. E. Muller, "Detection of lipid core coronary plaques in autopsy specimens with a novel catheter-based near-infrared spectroscopy system," JACC Cardiovasc. Imaging 1(5), 638-648 (2008 93-110 (1985).

Real-time volumetric lipid imaging in vivo by intravascular photoacoustics at 20 frames per second

“…Despite using a pulse energy which is one order of magnitude lower than that used previously in IVPA/US systems working at 1.7 µm, the PA SNR achieved in our imaging system was 20 dB, comparable to earlier reports [22,23]. We used pork lard as a lipid target for in vivo imaging, which has a different lipid composition, and thus a slightly different absorption spectrum, compared to lipid-rich plaque [20]. However, at the selected wavelength (1720 nm), both pork lard and plaque generate strong PA signals.…”

“…Tissue contrast in IVPA can be chosen by tuning the excitation wavelength to a specific absorption band of the imaging target. We target atherosclerotic plaque lipid, the most prevalent marker for identifying vulnerable plaques, by choosing an excitation wavelength that excites a PA signal from lipids [12,[14][15][16][17], and ideally from atherosclerotic lipids alone [18][19][20]. Its co-registered IVUS image provides the complementary structure information of the artery wall.…”

Biomedical photoacoustics: fundamentals, instrumentation and perspectives on nanomedicine

“…In particular, based on the characteristic optical absorptions of lipid in the NIR range, IVPAI is capable of imaging lipids in human coronary atherosclerosis ex vivo and is promisingly translated to in vivo clinics. 92,93 Wang et al injected AuNPs on a diseased rabbit aorta to image macrophages which are important indicators of atherosclerotic formation at the early stage ( Figure 9). 46 They showed that IVPAI validated the presence and the location of atherosclerotic plaques based on their outstanding contrast enhancement of AuNPs.…”

New Potassium Sodium Niobate Single Crystal with Thickness-independent High-performance for Photoacoustic Angiography of Atherosclerotic Lesion

“…To address this issue, intravascular photoacoustic (IVPA) imaging seems to be an alternative method to detect lipid pool and atherosclerotic calcification. In this hybrid imaging process, a tiny single element ultrasound transducer, integrated with a laser fiber and driven by a rotational shaft, is placed at an appropriate position inside the blood vessel to detect the photoacoustic signals inside the tissue, which were generated by the absorption of a short pulsed laser101112. Because the proposed intravascular photoacoustic imaging process combines the advantages of high ultrasonic resolution and strong optical absorption contrast, it shows great potential for the detecting of atherosclerotic plaque1314.…”

“…As the core part of the transducer, lead-based piezoelectric materials have been most popular for IVPA applications because of their excellent piezoelectric behavior101112131415. However, in view of environmental protection and human safety issues, the use of lead is a problem due to its toxicity.…”