Wang Xin, Wu Linhui, Yi Xi, Zhang Yanqi, Zhang Limin, Zhao Huijuan, Gao Feng
College of Precision Instrument and Optoelectronics Engineering, Tianjin University, Tianjin 300072, China.
College of Precision Instrument and Optoelectronics Engineering, Tianjin University, Tianjin 300072, China ; Tianjin Key Laboratory of Biomedical Detecting Techniques and Instruments, Tianjin 300072, China.
Comput Math Methods Med. 2015;2015:739459. doi: 10.1155/2015/739459. Epub 2015 May 19.
Due to both the physiological and morphological differences in the vascularization between healthy and diseased tissues, pharmacokinetic diffuse fluorescence tomography (DFT) can provide contrast-enhanced and comprehensive information for tumor diagnosis and staging. In this regime, the extended Kalman filtering (EKF) based method shows numerous advantages including accurate modeling, online estimation of multiparameters, and universal applicability to any optical fluorophore. Nevertheless the performance of the conventional EKF highly hinges on the exact and inaccessible prior knowledge about the initial values. To address the above issues, an adaptive-EKF scheme is proposed based on a two-compartmental model for the enhancement, which utilizes a variable forgetting-factor to compensate the inaccuracy of the initial states and emphasize the effect of the current data. It is demonstrated using two-dimensional simulative investigations on a circular domain that the proposed adaptive-EKF can obtain preferable estimation of the pharmacokinetic-rates to the conventional-EKF and the enhanced-EKF in terms of quantitativeness, noise robustness, and initialization independence. Further three-dimensional numerical experiments on a digital mouse model validate the efficacy of the method as applied in realistic biological systems.
由于健康组织和患病组织在血管生成方面存在生理和形态差异，药代动力学扩散荧光断层扫描（DFT）可为肿瘤诊断和分期提供对比增强的全面信息。在此情况下，基于扩展卡尔曼滤波（EKF）的方法显示出诸多优势，包括精确建模、多参数在线估计以及对任何光学荧光团的普遍适用性。然而，传统EKF的性能高度依赖于关于初始值的精确且难以获取的先验知识。为解决上述问题，基于双室模型提出了一种自适应EKF方案用于增强，该方案利用可变遗忘因子来补偿初始状态的不准确性并强调当前数据的影响。通过在圆形域上进行二维模拟研究表明，所提出的自适应EKF在定量性、噪声鲁棒性和初始化独立性方面，相对于传统EKF和增强型EKF能够获得更好的药代动力学速率估计。在数字小鼠模型上进行的进一步三维数值实验验证了该方法在实际生物系统中的有效性。
