Univ. of Toronto, Canada.
Sunnybrook Research Institute, Canada.
J Biomed Opt. 2019 Jun;24(6):1-12. doi: 10.1117/1.JBO.24.6.066003.
Lipid composition of atherosclerotic plaques is considered to be highly related to plaque vulnerability. Therefore, a specific diagnostic or imaging modality that can sensitively evaluate plaques' necrotic core is desirable in atherosclerosis imaging. In this regard, intravascular photoacoustic (IVPA) imaging is an emerging plaque detection technique that provides lipid-specific chemical information from an arterial wall with great optical contrast and long acoustic penetration depth. While, in the near-infrared window, a 1210-nm optical source is usually chosen for IVPA applications since lipids exhibit a strong absorption peak at that wavelength, the sensitivity problem arises in the conventional single-ended systems as other arterial tissues also show some degree of absorption near that spectral region, thereby generating undesirably interfering photoacoustic (PA) signals. A theory of the high-frequency frequency-domain differential photoacoustic radar (DPAR) modality is introduced as a unique detection technique for accurate and molecularly specific evaluation of vulnerable plaques. By assuming two low-power continuous-wave optical sources at ∼1210 and ∼970 nm in a differential manner, DPAR theory and the corresponding simulation/experiment studies suggest an imaging modality that is only sensitive and specific to the spectroscopically defined imaging target, cholesterol.
动脉粥样硬化斑块的脂质组成被认为与斑块易损性高度相关。因此，在动脉粥样硬化成像中，需要一种能够敏感评估斑块坏死核心的特定诊断或成像方式。在这方面，血管内光声（IVPA）成像是一种新兴的斑块检测技术，它提供了从动脉壁获得的具有良好光学对比度和长声学穿透深度的脂质特异性化学信息。然而，在近红外窗口中，由于脂质在该波长处表现出很强的吸收峰，因此通常选择 1210nm 的光学源用于 IVPA 应用，但在传统的单端系统中会出现灵敏度问题，因为其他动脉组织在该光谱区域附近也表现出一定程度的吸收，从而产生不希望的干扰光声（PA）信号。本文提出了高频频域差分光声雷达（DPAR）模态的理论，作为一种用于准确和分子特异性评估易损斑块的独特检测技术。通过假设在差分方式下使用两个约 1210nm 和 970nm 的低功率连续波光学源，DPAR 理论和相应的模拟/实验研究表明，该成像方式仅对光谱定义的成像目标（胆固醇）具有敏感性和特异性。
