Washington University in St. Louis, Department of Biomedical Engineering, St. Louis, Missouri, United States.
J Biomed Opt. 2017 Apr 1;22(4):41018. doi: 10.1117/1.JBO.22.4.041018.
Photoacoustic computed tomography (PACT) is an emerging computed imaging modality that exploits optical contrast and ultrasonic detection principles to form images of the absorbed optical energy density within tissue. If the object possesses spatially variant acoustic properties that are unaccounted for by the reconstruction method, the estimated image can contain distortions. While reconstruction methods have recently been developed to compensate for this effect, they generally require the object’s acoustic properties to be known a priori. To circumvent the need for detailed information regarding an object’s acoustic properties, we previously proposed a half-time reconstruction method for PACT. A half-time reconstruction method estimates the PACT image from a data set that has been temporally truncated to exclude the data components that have been strongly aberrated. However, this method can be improved upon when the approximate sizes and locations of isolated heterogeneous structures, such as bones or gas pockets, are known. To address this, we investigate PACT reconstruction methods that are based on a variable data truncation (VDT) approach. The VDT approach represents a generalization of the half-time approach, in which the degree of temporal truncation for each measurement is determined by the distance between the corresponding ultrasonic transducer location and the nearest known bone or gas void location. Computer-simulated and experimental data are employed to demonstrate the effectiveness of the approach in mitigating artifacts due to acoustic heterogeneities.
光声计算机断层扫描(PACT)是一种新兴的计算成像模式,利用光学对比度和超声检测原理形成组织内吸收光能量密度的图像。如果物体具有重建方法无法解释的空间变化的声特性,则估计的图像可能会包含失真。虽然最近已经开发了重建方法来补偿这种影响,但它们通常需要事先知道物体的声特性。为了避免需要有关物体声特性的详细信息,我们之前提出了一种用于 PACT 的半时间重建方法。半时间重建方法从已被时间截断以排除强烈失真的数据分量的数据集估计 PACT 图像。然而,当已知孤立异质结构(如骨骼或气穴)的近似大小和位置时,此方法可以得到改进。为了解决这个问题,我们研究了基于可变数据截断(VDT)方法的 PACT 重建方法。VDT 方法是半时间方法的推广,其中每个测量的时间截断程度由相应的超声换能器位置和最近已知的骨骼或气隙位置之间的距离决定。使用计算机模拟和实验数据证明了该方法在减轻由于声异质性引起的伪影方面的有效性。