Scanning Acoustic Microscopy and Time-Resolved Fluorescence Spectroscopy for Characterization of Atherosclerotic Plaques

Abstract

Atherosclerotic plaques constitute the primary cause of heart attack and stroke. However, we still lack a clear identification of the plaques. Here, we evaluate the feasibility of scanning acoustic microscopy (SAM) and time-resolved fluorescence spectroscopy (TRFS) in atherosclerotic plaque characterization. We perform dual-modality microscopic imaging of the human carotid atherosclerotic plaques. We first show that the acoustic impedance values are statistically higher in calcified regions compared with the collagen-rich areas. We then use CdTe/CdS quantum dots for imaging the atherosclerotic plaques by TRFS and show that fluorescence lifetime values of the quantum dots in collagen-rich areas are notably different from the ones in calcified areas. In summary, both modalities are successful in differentiating the calcified regions from the collagen-rich areas within the plaques indicating that these techniques are confirmatory and may be combined to characterize atherosclerotic plaques in the future.

Carotid artery plaque structure in the context of symptomatic/asymptomatic nature of carotid artery stenosis

“…While IVUS and OCT are useful methods for atherosclerotic lesions, NIRS can detect lipid components. 16 In a study, Agatston calcium score was assumed to be a predictor factor for plaque vulnerability. 15 The higher scores meant lower symptoms ipsilateral to the carotid lesion.…”

“…15 As we previously reported, scanning acoustic microscopy (SAM) may be considered as another optional imaging tool obtaining useful information about structural and mechanical information of atherosclerotic plaque. 8,16 SAM provides differentiation between collagen-rich areas and calcifi ed regions, so it may be benefi cial to determine high-risk lesions in clinics. In our study, we have enlarged the patient number and evaluated the plaque structure in the context of symptomatic or asymptomatic disease.…”

Determination of Ultrastructural Properties of Human Carotid Atherosclerotic Plaques by Scanning Acoustic Microscopy, Micro-Computer Tomography, Scanning Electron Microscopy and Energy Dispersive X-Ray Spectroscopy

“…2, make SAM a suitable tool for the determination of microcalcifications, which are indicators of vulnerability. Microcalcifications in other tissue types can also be examined by SAM, since calcium deposition is stiffer than any human tissue with a greater acoustic impedance value 38,39 , and therefore easily distinguishable within tissues like breast or prostate. Doppler ultrasonography has been widely used to characterize carotid plaques by obtaining plaque morphology, which is an indicator of vulnerability 40 .…”

Atrial fibrillation designation with micro-Raman spectroscopy and scanning acoustic microscope

“…The coupling medium between the quartz lens and the substrate is distilled water. The ultrasonic signals generated by the transducer ( ) are scanned 2-dimensionally by the X-Y stage and reflected back both from the reference ( ) and also the target material ( ), then thsese reflected signals are compared and analyzed to generate the intensity and acoustic impedance maps of the region of interest with 300 x 300 sampling points with a lateral resolution of approximately 20 42 .…”