Matthews Thomas P, Poudel Joemini, Li Lei, Wang Lihong V, Anastasio Mark A
Department of Biomedical Engineering, Washington University in St. Louis, 1 Brookings Dr., St. Louis, MO 63130.
Caltech Optical Imaging Laboratory, Andrew and Peggy Cherng Department of Medical Engineering, Department of Electrical Engineering, California Institute of Technology, 1200 E. California Blvd., MC 138-78, Pasadena, CA 91125.
SIAM J Imaging Sci. 2018;11(2):1560-1588. doi: 10.1137/17M1153649. Epub 2018 Jun 5.
Accurate estimation of the initial pressure distribution in photoacoustic computed tomography (PACT) depends on knowledge of the sound speed distribution. However, the sound speed distribution is typically unknown. Further, the initial pressure and sound speed distributions cannot both, in general, be stably recovered from PACT measurements alone. In this work, a joint reconstruction (JR) method for the initial pressure distribution and a low-dimensional parameterized model of the sound speed distribution is proposed. By employing information about the structure of the sound speed distribution, both the initial pressure and sound speed can be accurately recovered. The JR problem is solved by use of a proximal optimization method that allows constraints and non-smooth regularization functions for the initial pressure distribution. The gradients of the cost function with respect to the initial pressure and sound speed distributions are calculated by use of an adjoint state method that has the same per-iteration computational cost as calculating the gradient with respect to the initial pressure distribution alone. This approach is evaluated through 2D computer-simulation studies for a small animal imaging model and by application to experimental in vivo measurements of a mouse.
光声计算机断层扫描（PACT）中初始压力分布的准确估计取决于声速分布的知识。然而，声速分布通常是未知的。此外，一般来说，仅从PACT测量中无法稳定地恢复初始压力和声速分布。在这项工作中，提出了一种用于初始压力分布和低维参数化声速分布模型的联合重建（JR）方法。通过利用关于声速分布结构的信息，可以准确地恢复初始压力和声速。通过使用近端优化方法来解决JR问题，该方法允许对初始压力分布施加约束和非光滑正则化函数。通过使用伴随状态方法计算成本函数相对于初始压力和声速分布的梯度，该方法与仅计算相对于初始压力分布的梯度具有相同的每次迭代计算成本。通过对小动物成像模型的二维计算机模拟研究以及应用于小鼠的体内实验测量来评估这种方法。
