University of Virginia, Department of Biomedical Engineering, Charlottesville, VA 22908, USA.
J Biomed Opt. 2013 May;18(5):56009. doi: 10.1117/1.JBO.18.5.056009.
Intravascular near-infrared fluorescence (NIRF) imaging offers a new approach for characterizing atherosclerotic plaque, but random catheter positioning within the vessel lumen results in variable light attenuation and can yield inaccurate measurements. We hypothesized that NIRF measurements could be corrected for variable light attenuation through blood by tracking the location of the NIRF catheter with intravascular ultrasound (IVUS). In this study, a combined NIRF-IVUS catheter was designed to acquire coregistered NIRF and IVUS data, an automated image processing algorithm was developed to measure catheter-to-vessel wall distances, and depth-dependent attenuation of the fluorescent signal was corrected by an analytical light propagation model. Performance of the catheter sensing distance correction method was evaluated in coronary artery phantoms and ex vivo arteries. The correction method produced NIRF estimates of fluorophore concentrations, in coronary artery phantoms, with an average root mean square error of 17.5%. In addition, the correction method resulted in a statistically significant improvement in correlation between spatially resolved NIRF measurements and known fluorophore spatial distributions in ex vivo arteries (from r = 0.24 to 0.69, p < 0.01, n = 6). This work demonstrates that catheter-to-vessel wall distances, measured from IVUS images, can be employed to compensate for inaccuracies caused by variable intravascular NIRF sensing distances.
血管内近红外荧光（NIRF）成像是一种用于描述动脉粥样硬化斑块的新方法，但由于导管在血管腔内的随机定位，会导致光衰减的变化，从而产生不准确的测量结果。我们假设，通过血管内超声（IVUS）追踪 NIRF 导管的位置，可以对 NIRF 测量结果进行校正，以补偿因光衰减而导致的测量误差。在这项研究中，设计了一种组合式 NIRF-IVUS 导管，用于获取共配准的 NIRF 和 IVUS 数据，开发了一种自动图像处理算法来测量导管到血管壁的距离，并通过分析光传播模型校正荧光信号的深度依赖性衰减。在冠状动脉模型和离体动脉中评估了导管感测距离校正方法的性能。该校正方法对冠状动脉模型中的荧光团浓度进行了 NIRF 估计，其平均均方根误差为 17.5%。此外，该校正方法还显著提高了离体动脉中空间分辨 NIRF 测量值与已知荧光团空间分布之间的相关性（从 r = 0.24 到 0.69，p < 0.01，n = 6）。这项工作表明，可以使用从 IVUS 图像测量的导管到血管壁的距离来补偿因血管内 NIRF 感测距离变化而导致的不准确性。
