Application of a maximum likelihood algorithm to ultrasound modulated optical tomography.
Application of a maximum likelihood algorithm to ultrasound modulated optical tomography.
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最大似然算法在超声调制光学断层扫描中的应用。
DOI：
10.1117/1.jbo.17.2.026014
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发表时间：
2012
影响因子：
3.5
通讯作者：
Huynh NT
中科院分区：
文献类型：
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作者：
Huynh NT
在脉冲超声调制光学层析成像(USMOT)中，超声(US)脉冲作为扫描探头在样品内传播，调制沿其传播轴空间分布的散射光。检测和处理调制信号可以提供沿US轴的1维图像。开发了一种简单的模型，其中所检测的信号被建模为US脉冲和介质沿US轴的性质(超声/光学)的卷积。基于该模型，建立了一种最大似然(ML)图像重建方法。首次从理论和实验两个方面研究了USMOT信号的最大似然技术。ML方法反转数据以检索样品沿US轴的空间变化特性，并且可以获得与光学特性成比例的信号。仿真结果表明，即使在信噪比接近1的情况下，最大似然方法也可以作为脉冲USMOT信号的一种有用的重建工具。使用5 cm厚的组织体模(散射系数、各向异性因子)的实验数据表明，使用10 MHz换能器，轴向分辨率为160μm，横向分辨率为600μm。
In pulsed ultrasound modulated optical tomography (USMOT), an ultrasound (US) pulse performs as a scanning probe within the sample as it propagates, modulating the scattered light spatially distributed along its propagation axis. Detecting and processing the modulated signal can provide a 1-dimensional image along the US axis. A simple model is developed wherein the detected signal is modelled as a convolution of the US pulse and the properties (ultrasonic/optical) of the medium along the US axis. Based upon this model, a maximum likelihood (ML) method for image reconstruction is established. For the first time to our knowledge, the ML technique for an USMOT signal is investigated both theoretically and experimentally. The ML method inverts the data to retrieve the spatially varying properties of the sample along the US axis, and a signal proportional to the optical properties can be acquired. Simulated results show that the ML method can serve as a useful reconstruction tool for a pulsed USMOT signal even when the signal-to-noise ratio (SNR) is close to unity. Experimental data using 5 cm thick tissue phantoms (scattering coefficient, anisotropy factor) demonstrate that the axial resolution is 160μm and the lateral resolution is 600μm using a 10 MHz transducer.