1 清华大学生物医学工程系, 北京 100086
2 清华大学电子工程系, 北京 100086
光声计算断层成像是近年发展起来的一种非入侵式和非电离式的新型生物医学成像方法,其临床应用对成像精度要求较高。生物组织内声速分布的不均匀性时常造成重建的光声图像中存在较为严重的伪影。实现光声IP和声速分布的联合重建是改善成像效果、去除成像伪影的重要途径之一,也是仅通过光声单一模态的信息获取就可以获得多模态信息(包括光学和声学信息)的崭新途径。总结了几种本研究组近年来开发的光声-声速联合重建方法,包括基于特征耦合、基于波前整形以及基于信号互补的方法。同时,分析了这几种方法的优劣势和适用场景,以期帮助人们更好地利用这些方法解决光声图像质量提高和多模态图像获取的问题。
医用光学 光声成像 医学影像 声速矫正 声速断层成像 多模态成像 中国激光
2021, 48(15): 1507001
Author Affiliations
Abstract
1 Department of Biomedical Engineering, School of Medicine Tsinghua University, Beijing, 100084, China
2 Beijing Advanced Information & Industrial Technology Research Institute Beijing Information Science & Technology University Beijing, 100192, China
Intensity-based quantitative fluorescence resonance energy transfer (FRET) is a technique to measure the distance of molecules in scale of a few nanometers which is far beyond optical diffraction limit. This widely used technique needs complicated experimental process and manual image analyses to obtain precise results, which take a long time and restrict the application of quantitative FRET especially in living cells. In this paper, a simplified and automatic quantitative FRET (saqFRET) method with high efficiency is presented. In saqFRET, photoactivatable acceptor PA-mCherry and optimized excitation wavelength of donor enhanced green fluorescent protein (EGFP) are used to simplify FRET crosstalk elimination. Traditional manual image analyses are time consuming when the dataset is large. The proposed automatic image analyses based on deep learning can analyze 100 samples within 30 s and demonstrate the same precision as manual image analyses.
Resonance energy transfer fluorescence living cells photoactivatable deep network Journal of Innovative Optical Health Sciences
2020, 13(6): 2050021
Author Affiliations
Abstract
Department of Biomedical Engineering, School of Medicine, Tsinghua University, Beijing 100084, China
For fluorescence molecular tomography (FMT), image quality could be improved by incorporating a sparsity constraint. The L1 norm regularization method has been proven better than the L2 norm, like Tikhonov regularization. However, the Tikhonov method was found capable of achieving a similar quality at a high iteration cost by adopting a zeroing strategy. By studying the reason, a Tikhonov-regularization-based projecting sparsity pursuit method was proposed that reduces the iterations significantly and achieves good image quality. It was proved in phantom experiments through time-domain FMT that the method could obtain higher accuracy and less oversparsity and is more applicable for heterogeneous-target reconstruction, compared with several regularization methods implemented in this Letter.
fluorescence molecular tomography sparsity pursuit Tikhonov regularization good image quality high efficiency Chinese Optics Letters
2020, 18(1): 011701
Author Affiliations
Abstract
1 Department of Biomedical Engineering School of Medicine, Tsinghua University Beijing 100084, P. R. China
2 Center for Biomedical Imaging Research Tsinghua University Beijing 100084, P. R. China
A compact volume holographic imaging (VHI) method that can detect fluorescence objects located in diffusive medium in spectral selective imaging manner is presented. The enlargement of lateral field of view of the VHI system is realized by using broadband illumination and demagni fication optics. Each target spectrum of fluorescence emitting from a diffusive medium is probed by tuning the inclination angle of the transmission volume holographic grating (VHG). With the use of the single transmission VHG, fluorescence images with different spectrum are obtained sequentially and precise three-dimensional (3D) information of deep fluorescent objects located in a diffusive medium can be reconstructed from these images. The results of phantom experiments demonstrate that two fluorescent objects with a sub-millimeter distance can be resolved by spectral selective imaging.
Volume holographic grating diffusive medium fluorescence molecular imaging Journal of Innovative Optical Health Sciences
2016, 9(2): 1650010
Author Affiliations
Abstract
1 Department of Biomedical Engineering, Tsinghua University, Beijing 100084, China
2 Center for Biomedical Imaging Research, Tsinghua University, Beijing 100084, China
A reconstruction method guided by early-photon fluorescence yield tomography is proposed for time-domain fluorescence lifetime tomography (FLT) in this study. The method employs the early-arriving photons to reconstruct a fluorescence yield map, which is utilized as a priori information to reconstruct the FLT via all the photons along the temporal-point spread functions. Phantom experiments demonstrate that, compared with the method using all the photons for reconstruction of fluorescence yield and lifetime maps, the proposed method can achieve higher spatial resolution and reduced crosstalk between different targets without sacrificing the quantification accuracy of lifetime and contrast between heterogeneous targets.
170.3880 Medical and biological imaging 170.3010 Image reconstruction techniques 170.6960 Tomography 170.6920 Time-resolved imaging Chinese Optics Letters
2016, 14(7): 071702
Author Affiliations
Abstract
1 Department of Biomedical Engineering, School of Medicine, Tsinghua University, Beijing 100084, China
2 Tsinghua-Peking Center for Life Sciences, Beijing 100084, China
3 Center for Biomedical Imaging Research, Tsinghua University, Beijing 100084, China
In order to improve the reconstruction accuracy in fluorescence molecular tomography (FMT), a common approach is to increase the number of fluorescence data or projections. However, this approach consumes too much memory space and computational time. In this Letter, a data compression strategy that involves the removal of the redundant information from both intra- and inter-projections is proposed to reduce the dimension of the FMT inverse problem. The performance of this strategy is tested with phantom and in vivo mouse experiments. The results demonstrate that the proposed data compression strategy can accelerate the FMT reconstruction nearly tenfold and almost without any quality degradation.
100.3010 Image reconstruction techniques 100.3190 Inverse problems 260.2510 Fluorescence Chinese Optics Letters
2015, 13(7): 071002
Author Affiliations
Abstract
1 Department of Biomedical Engineering, Tsinghua University Beijing 100084, P. R. China
2 Center for Biomedical Imaging Research, Tsinghua University Beijing 100084, P. R. China
Challenges remain in imaging fast biological processes in vivo with fluorescence molecular tomography (FMT) due to the long data acquisition time. Data acquisition with limited projections can greatly reduce the time consumption, but the influence of limited-projection on reconstruction quality is currently unclear. Both numerical simulations and a phantom experiment are conducted to analyze this problem. Through a systematic investigation of all the results reconstructed from different numbers of projections, we evaluate the influence of limited-projection data on FMT. A mouse experiment is also performed to validate our work. A general relationship between the number of projections and reconstruction quality is obtained which indicates that the projection number of three is preferred for fast FMT experiment.
FMT inverse problem limited-projection Journal of Innovative Optical Health Sciences
2012, 5(3): 1250020
