A Method for Fluorescent Diffuse Optical Tomography Based on Lattice Boltzmann Forward Model on GPU Parallelization / 中国医疗器械杂志

Fluorescent Diffuse Optical Tomography (FDOT) is an emerging imaging method with great prospects in fields of biology and medicine. However, the current solutions to the forward problem in FDOT are time consuming, which greatly limit the application. We proposed a method for FDOT based on Lattice Boltzmann forward model on GPU to greatly improve the computational efficiency. The Lattice Boltzmann Method (LBM) was used to construct the optical transmission model. This method separated the LBM into collision, streaming and boundary processing processes on GPUs to perform the LBM efficiently, which were local computational and inefficient on CPU. The feasibility of the proposed method was verified by the numerical phantom and the physical phantom experiments. The experimental results showed that the proposed method achieved the best performance of a 118-fold speed up under the precondition of simulation accuracy, comparing to the diffusion equation implemented by Finite Element Method (FEM) on CPU. Thus, the LBM on the GPU may efficiently solve the forward problem in FDOT.

A Fluorescence Diffusion Optical Tomography System Based on Lattice Boltzmann Forward Model / 中国医疗器械杂志

Fluorescence Diffuse Optical Tomography (FDOT) is significant for biomedical applications, such as medical diagnostics, drug research. The fluorescence probe distribution in biological tissues can be quantitatively and non-invasively obtained via FDOT, achieving targets positioning and detection. In order to reduce the cost of FDOT, this study designs a FDOT system based on Lattice Boltzmann forward model. The system is used to realize two functions of light propagation simulation and FDOT reconstruction, and is composed of a parameter module, an algorithm module, a result display module and a data interaction module. In order to verify the effectiveness of the platform, this study carries out the light propagation simulation experiment and the FDOT reconstruction experiment, respectively comparing the Monte Carlo (MC) light propagation simulation results and the real position of the light source to be reconstructed. Experiments show that the proposed FDOT system has good reliability and has a high promotion value.

Noninvasive numerical simulation of coronary fractional flow reserve based on lattice Boltzmann method / 生物医学工程学杂志

In order to investigate the application of lattice Boltzmann method (LBM) in the numerical simulation of computed tomography angiography-derived fractional flow reserve (FFR ), an idealized narrowed tube model and two coronary stenosis arterymodels are studied. Based on the open source code library (Palabos), the relative algorithm program in the development environment (Codeblocks) was improved. Through comparing and analyzing the results of FFR which is simulated by LBM and finite element analysis software ANSYS, and the feasibility of the numerical simulation of FFR by LBM was verified . The results show that the relative error between the results of LBM and finite element analysis software ANSYS is about 1%, which vertifies the feasibility of simulating the coronary FFR by LBM. The simulation of this study provides technical support for developing future FFR application software, and lays the foundation for the calculation of clinical FFR .

Hippocampus MRI Parallel Segmentation Using Three Dimensions Lattice Boltzmann Model with Prior Information / 中国医疗器械杂志

Getting volume change of hippocampus by segmenting on brain MRI is an important step in the diagnose of Alzheimer's disease and other brain disease. Three dimensional segmentation can make use of the correlation of image in gray and spatial position, so it has high accuracy. This paper proposes a novel three-dimensional lattice Boltzmann model combined with the surface evolution of deformable model and taking the prior information as an external force term to constrain the evolution of three dimensional surfaces. In order to solve the problem of high computational cost caused by 3D segmentation, the parallelization of the method is programmed on single GPU platform and dual GPU platform. Comparison experiments were set to test the accuracy of segmentation and computational efficiency between the novel LB method and another method by using 20 real AD patient's MRI from ADNI. In ensuring the accuracy of the segmentation, the time can be reduced to 12.76 s on single GPU platform, and 17.32 s on dual GPU platform, contrasting 132.43 s on CPU platform. It fully validates the characteristics of lattice Boltzmann method which can be highly parallelized.

Stent effects on hemodynamics of cerebral aneurysm by non-uniform lattice Boltzmann method / 医用生物力学

Objective To investigate the effects of triangle stents with different rotation angles on hemodynamics of cerebral aneurysms. Methods A non-uniform lattice Boltzmann method (LBM) was adopted to make local refinement on grids near the stent, and a scheme for the curved boundary conditions was used to numerically simulate the stented cerebral aneurysms. The stream plots of flows in the aneurysms, the velocity profiles at the aneurysm orifice and the velocity reduction were obtained and analyzed to evaluate the effects of stents with different rotation angles on treating cerebral aneurysms. Results With respect to velocity reduction, the best treatment effect was achieved in the triangle stent with rotation angle of 180°, while the triangle stent without any rotation caused the smallest velocity reduction. In addition，the dynamic differences were not obvious in triangle stents with different rotation angles at small porosities. Conclusions The non-uniform LBM combined with curved boundary conditions can be used to study hemodynamic characteristics of the cerebral aneurysm accurately, which provides reference for the design of such stent and also offers some guidance for intervention therapy in clinic.

Numerical study on multiscale simulation for hemodynamics of systemic-pulmonary shunt procedure based on lattice Boltzmann method / 医用生物力学

Objective Based on time-coupled multiscale coupling algorithm, to simulate the hemodynamics after systemic-pulmonary shunt procedure on single ventricular patient so as to obtain the local three-dimensional (3D) fluid field and global hemodynamic information before and after surgery. MethodsFirstly, the 0D-3D coupled multiscale hemodynamic model of systemic-pulmonary shunt procedure was established based on the lumped parameter model (0D) before surgery and the shunt model (3D), then the 0D-3D interface coupling condition and the time coupling algorithm were discussed. Secondly, the multiscale simulation of 3D CFD (computational fluid dynamics) model coupled with 0D lumped parameter model was realized based on lattice Boltzmann method. Finally, the multiscale simulation results were compared with patient’s 0D simulation results to study the hemodynamic changes before and after surgery. Results The global hemodynamic change and local 3D flow pattern were obtained by this multiscale simulation. The pulmonary blood flow distribution ratio was increased from 32.21% to 57.8%. Conclusions The systemic-pulmonary shunt procedure can effectively increase the blood supply of pulmonary circulation by implanting the shunt between the systematic circulation and pulmonary circulation. The geometrical multiscale method can effectively simulate both the coarse global and detailed local cardiovascular hemodynamic changes, which is of great significance in pre-operation planning of cardiovascular surgery.