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Glückstad J, Gejl Madsen AE. HoloTile light engine: new digital holographic modalities and applications. Rep Prog Phys 2024; 87:034401. [PMID: 38373355 DOI: 10.1088/1361-6633/ad2aca] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Accepted: 02/19/2024] [Indexed: 02/21/2024]
Abstract
HoloTile is a patented computer generated holography approach with the aim of reducing the speckle noise caused by the overlap of the non-trivial physical extent of the point spread function in Fourier holographic systems from adjacent frequency components. By combining tiling of phase-only of rapidly generated sub-holograms with a PSF-shaping phase profile, each frequency component-or output 'pixel'- in the Fourier domain is shaped to a desired non-overlapping profile. In this paper, we show the high-resolution, speckle-reduced reconstructions that can be achieved with HoloTile, as well as present new HoloTile modalities, including an expanded list of PSF options with new key properties. In addition, we discuss numerous applications for which HoloTile, its rapid hologram generation, and the new PSF options may be an ideal fit, including optical trapping and manipulation of particles, volumetric additive printing, information transfer and quantum communication.
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Affiliation(s)
- Jesper Glückstad
- SDU Centre for Photonics Engineering, University of Southern Denmark, Campusvej 55, Odense-M 5230, Denmark
| | - Andreas Erik Gejl Madsen
- SDU Centre for Photonics Engineering, University of Southern Denmark, Campusvej 55, Odense-M 5230, Denmark
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2
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Martínez S, Martínez OE. PSF-Radon transform algorithm: Measurement of the point-spread function from the Radon transform of the line-spread function. Microsc Res Tech 2024. [PMID: 38419356 DOI: 10.1002/jemt.24526] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Revised: 01/06/2024] [Accepted: 02/10/2024] [Indexed: 03/02/2024]
Abstract
In this article, we present a new method called point spread function (PSF)-Radon transform algorithm. This algorithm consists on recovering the instrument PSF from the Radon transform (in the line direction axis) of the line spread function (i.e., the image of a line). We present the method and tested with synthetic images, and real images from macro lens camera and microscopy. A stand-alone program along with a tutorial is available, for any interested user, in Martinez (PSF-Radon transform algorithm, standalone program). RESEARCH HIGHLIGHTS: Determining the instrument PSF is a key issue. Precise PSF determinations are mandatory if image improvement is performed numerically by deconvolution. Much less exposure time to achieve the same performance than a measurement of the PSF from a very small bead. Does not require having to adjust the PSF by an analytical function to overcome the noise uncertainties.
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Affiliation(s)
- Sandra Martínez
- Departamento de Matemática, FCEyN-UBA and IMAS, CONICET, Buenos Aires, Argentina
| | - Oscar E Martínez
- Laboratorio de Fotónica, Instituto de Ingeniería Biomédica, FI-UBA, CONICET, Buenos Aires, Argentina
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Gao G, Li L, Chen H, Jiang N, Li S, Bian Q, Bao H, Rao C. No-Reference Quality Assessment of Extended Target Adaptive Optics Images Using Deep Neural Network. Sensors (Basel) 2023; 24:1. [PMID: 38202863 PMCID: PMC10781174 DOI: 10.3390/s24010001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Revised: 12/08/2023] [Accepted: 12/13/2023] [Indexed: 01/12/2024]
Abstract
This paper proposes a supervised deep neural network model for accomplishing highly efficient image quality assessment (IQA) for adaptive optics (AO) images. The AO imaging systems based on ground-based telescopes suffer from residual atmospheric turbulence, tracking error, and photoelectric noise, which can lead to varying degrees of image degradation, making image processing challenging. Currently, assessing the quality and selecting frames of AO images depend on either traditional IQA methods or manual evaluation by experienced researchers, neither of which is entirely reliable. The proposed network is trained by leveraging the similarity between the point spread function (PSF) of the degraded image and the Airy spot as its supervised training instead of relying on the features of the degraded image itself as a quality label. This approach is reflective of the relationship between the degradation factors of the AO imaging process and the image quality and does not require the analysis of the image's specific feature or degradation model. The simulation test data show a Spearman's rank correlation coefficient (SRCC) of 0.97, and our method was also validated using actual acquired AO images. The experimental results indicate that our method is more accurate in evaluating AO image quality compared to traditional IQA methods.
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Affiliation(s)
- Guoqing Gao
- Key Laboratory of Adaptive Optics, Chinese Academy of Sciences, Chengdu 610209, China; (G.G.); (H.C.); (N.J.); (Q.B.); (C.R.)
- School of Optoelectronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China
- Institute of Optics and Electronics, Chinese Academy of Sciences, Chengdu 610209, China
- University of Chinese Academy of Sciences, Beijing 101408, China
| | - Lingxiao Li
- Key Laboratory of Adaptive Optics, Chinese Academy of Sciences, Chengdu 610209, China; (G.G.); (H.C.); (N.J.); (Q.B.); (C.R.)
- Institute of Optics and Electronics, Chinese Academy of Sciences, Chengdu 610209, China
| | - Hao Chen
- Key Laboratory of Adaptive Optics, Chinese Academy of Sciences, Chengdu 610209, China; (G.G.); (H.C.); (N.J.); (Q.B.); (C.R.)
- Institute of Optics and Electronics, Chinese Academy of Sciences, Chengdu 610209, China
| | - Ning Jiang
- Key Laboratory of Adaptive Optics, Chinese Academy of Sciences, Chengdu 610209, China; (G.G.); (H.C.); (N.J.); (Q.B.); (C.R.)
- Institute of Optics and Electronics, Chinese Academy of Sciences, Chengdu 610209, China
- University of Chinese Academy of Sciences, Beijing 101408, China
| | - Shuqi Li
- Key Laboratory of Adaptive Optics, Chinese Academy of Sciences, Chengdu 610209, China; (G.G.); (H.C.); (N.J.); (Q.B.); (C.R.)
- Institute of Optics and Electronics, Chinese Academy of Sciences, Chengdu 610209, China
- University of Chinese Academy of Sciences, Beijing 101408, China
| | - Qing Bian
- Key Laboratory of Adaptive Optics, Chinese Academy of Sciences, Chengdu 610209, China; (G.G.); (H.C.); (N.J.); (Q.B.); (C.R.)
- Institute of Optics and Electronics, Chinese Academy of Sciences, Chengdu 610209, China
- University of Chinese Academy of Sciences, Beijing 101408, China
| | - Hua Bao
- Key Laboratory of Adaptive Optics, Chinese Academy of Sciences, Chengdu 610209, China; (G.G.); (H.C.); (N.J.); (Q.B.); (C.R.)
- Institute of Optics and Electronics, Chinese Academy of Sciences, Chengdu 610209, China
- University of Chinese Academy of Sciences, Beijing 101408, China
| | - Changhui Rao
- Key Laboratory of Adaptive Optics, Chinese Academy of Sciences, Chengdu 610209, China; (G.G.); (H.C.); (N.J.); (Q.B.); (C.R.)
- School of Optoelectronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China
- Institute of Optics and Electronics, Chinese Academy of Sciences, Chengdu 610209, China
- University of Chinese Academy of Sciences, Beijing 101408, China
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Hwang J, Park IY, Jung MK, Jung H, Ogawa T. Enhanced Scanning Electron Microscopy Using Auto-Optimized Image Restoration With Constrained Least Squares Filter for Nanoscience. Microsc Microanal 2023; 29:1618-1627. [PMID: 37584512 DOI: 10.1093/micmic/ozad076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2023] [Revised: 06/01/2023] [Accepted: 07/16/2023] [Indexed: 08/17/2023]
Abstract
The growing demands of nanoscience require the continuous improvement of visualization methods. The imaging performance of scanning electron microscopy (SEM) is fundamentally limited by the point spread function of the electron beam and degrades because of noise. This paper proposes an auto-optimization algorithm based on deconvolution for the restoration of SEM images. This algorithm uses a constrained least squares filter and does not dependent on the user's experience or the availability of nondegraded images. The proposed algorithm improved the quality of the SEM images of 10-nm Au nanoparticles, and achieved balance among the sharpness, contrast-to-noise ratio (CNR), and image artifacts. For the SEM image of 100-nm pitched line patterns, the analysis of the spatial frequencies allowed the 2.5-fold improvement of the intensity of 4-nm information, and the noise floor decreased approximately 32 times. Along with the results obtained by the application of the proposed algorithm to images of tungsten disulfide (WS2) flakes, carbon nanotubes (CNTs), and HeLa cells, the evaluation results confirm that the proposed algorithm can enhance the SEM imaging of nanoscale features that lie close to the microscope's resolution limit.
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Affiliation(s)
- Junhyeok Hwang
- Advanced Instrumentation Institute, Korea Research Institute of Standards and Science (KRISS), 267 Gajeong-ro, Yuseong, Daejeon 34113, Republic of Korea
- Major in Applied Measurement Science, University of Science and Technology (UST), 217 Gajeong-ro, Yuseong, Daejeon 34113, Republic of Korea
| | - In-Yong Park
- Advanced Instrumentation Institute, Korea Research Institute of Standards and Science (KRISS), 267 Gajeong-ro, Yuseong, Daejeon 34113, Republic of Korea
- Major in Applied Measurement Science, University of Science and Technology (UST), 217 Gajeong-ro, Yuseong, Daejeon 34113, Republic of Korea
| | - Min Kyo Jung
- Neural Circuit Research Group, Korea Brain Research Institute (KBRI), 61 Cheomdan-ro, Dong-gu, Daegu 41062, Republic of Korea
| | - Haewon Jung
- Advanced Instrumentation Institute, Korea Research Institute of Standards and Science (KRISS), 267 Gajeong-ro, Yuseong, Daejeon 34113, Republic of Korea
| | - Takashi Ogawa
- Advanced Instrumentation Institute, Korea Research Institute of Standards and Science (KRISS), 267 Gajeong-ro, Yuseong, Daejeon 34113, Republic of Korea
- Major in Applied Measurement Science, University of Science and Technology (UST), 217 Gajeong-ro, Yuseong, Daejeon 34113, Republic of Korea
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Shi L, Tan J. Discovery, Quantitative Recurrence, and Inhibition of Motion-Blur Hysteresis Phenomenon in Visual Tracking Displacement Detection. Sensors (Basel) 2023; 23:8024. [PMID: 37836856 PMCID: PMC10575234 DOI: 10.3390/s23198024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Revised: 09/19/2023] [Accepted: 09/19/2023] [Indexed: 10/15/2023]
Abstract
Motion blur is common in video tracking and detection, and severe motion blur can lead to failure in tracking and detection. In this work, a motion-blur hysteresis phenomenon (MBHP) was discovered, which has an impact on tracking and detection accuracy as well as image annotation. In order to accurately quantify MBHP, this paper proposes a motion-blur dataset construction method based on a motion-blur operator (MBO) generation method and self-similar object images, and designs APSF, a MBO generation method. The optimized sub-pixel estimation method of the point spread function (SPEPSF) is used to demonstrate the accuracy and robustness of the APSF method, showing the maximum error (ME) of APSF to be smaller than others (reduced by 86%, when motion-blur length > 20, motion-blur angle = 0), and the mean square error (MSE) of APSF to be smaller than others (reduced by 65.67% when motion-blur angle = 0). A fast image matching method based on a fast correlation response coefficient (FAST-PCC) and improved KCF were used with the motion-blur dataset to quantify MBHP. The results show that MBHP exists significantly when the motion blur changes and the error caused by MBHP is close to half of the difference of the motion-blur length between two consecutive frames. A general flow chart of visual tracking displacement detection with error compensation for MBHP was designed, and three methods for calculating compensation values were proposed: compensation values based on inter-frame displacement estimation error, SPEPSF, and no-reference image quality assessment (NR-IQA) indicators. Additionally, the implementation experiments showed that this error can be reduced by more than 96%.
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Affiliation(s)
- Lixiang Shi
- School of Mechanical and Electrical Engineering, Central South University, Changsha 410006, China;
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Ding Y, Gong Z, Chen Y, Hu J, Chen Y. Quantitative Analysis of Super Resolution in Electromagnetic Inverse Scattering for Microwave Medical Sensing and Imaging. Sensors (Basel) 2023; 23:7404. [PMID: 37687861 PMCID: PMC10490563 DOI: 10.3390/s23177404] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Revised: 08/21/2023] [Accepted: 08/22/2023] [Indexed: 09/10/2023]
Abstract
Microwave medical sensing and imaging (MMSI) has been a research hotspot in the past years. Imaging algorithms based on electromagnetic inverse scattering (EIS) play a key role in MMSI due to the super-resolution phenomenon. EIS problems generally employ far-field scattered data to reconstruct images. However, the far-field data do not include information outside the Ewald's sphere, so theoretically it is impossible to achieve super resolution. The reason for super resolution has not been clarified. The majority of the current research focuses on how nonlinearity affects the super-resolution phenomena in EIS. However, the mechanism of super-resolution in the absence of nonlinearity is routinely ignored. In this research, we address a prevalent yet overlooked problem where the image resolution due to scatterers of extended structures is incorrectly analyzed using the model of point scatterers. Specifically, the classical resolution of EIS is defined by the Rayleigh criterion which is only suitable for point-like scatterers. However, the super-resolution in EIS is often observed for general scatterers like cylinders, squares or Austria shapes. Subsequently, we provide theoretical results for the Born approximation framework in EIS, and employ the Sparrow criteria to quantify the resolution for symmetric objects of extended structures. Furthermore, the modified Sparrow criterion is proposed to calculate the resolution of asymmetric scatterers. Numerical examples show that the proposed approach can better explain the super-resolution phenomenon in EIS.
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Affiliation(s)
- Yahui Ding
- School of Electronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China; (Y.D.); (J.H.); (Y.C.)
| | - Zheng Gong
- Yangtze Delta Region Institute (Quzhou), University of Electronic Science and Technology of China, Quzhou 324003, China;
| | - Yifan Chen
- School of Life Sciences and Technology, University of Electronic Science and Technology of China, Chengdu 611731, China
| | - Jun Hu
- School of Electronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China; (Y.D.); (J.H.); (Y.C.)
| | - Yongpin Chen
- School of Electronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China; (Y.D.); (J.H.); (Y.C.)
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7
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Akbari Sekehravani E, Leone G. Evaluation of the Resolution in Inverse Scattering of Dielectric Cylinders for Medical Applications. Sensors (Basel) 2023; 23:7250. [PMID: 37631786 PMCID: PMC10459407 DOI: 10.3390/s23167250] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Revised: 08/05/2023] [Accepted: 08/15/2023] [Indexed: 08/27/2023]
Abstract
The inverse scattering problem has numerous significant applications, including in geophysical explorations, medical imaging, and radar imaging. To achieve better performance of the imaging system, theoretical knowledge of the resolution of the algorithm is required for most of these applications. However, analytical investigations about the resolution presently feel inadequate. In order to estimate the achievable resolution, we address the point spread function (PSF) evaluation of the scattered field for a single frequency and the multi-view case both for the near and the far fields and the scalar case when the angular domain of the incident field and observation ranges is a round angle. Instead of the common free space condition, an inhomogeneous background medium, consisting of a homogeneous dielectric cylinder with a circular cross-section in free space, is assumed. In addition, since the exact evaluation of the PSF can only be accomplished numerically, an analytical approximation of the resolution is also considered. For the sake of its comparison, the truncated singular value decomposition (TSVD) algorithm can be used to implement the exact PSF. We show how the behavior of the singular values and the resolution change by varying the permittivity of the background medium. The usefulness of the theoretical discussion is demonstrated in localizing point-like scatterers within a dielectric cylinder, so mimicking a scenario that may occur in breast cancer imaging. Numerical results are provided to validate the analytical investigations.
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Rahbek S, Schakel T, Mahmood F, Madsen KH, Philippens MEP, Hanson LG. Optimized flip angle schemes for the split acquisition of fast spin-echo signals (SPLICE) sequence and application to diffusion-weighted imaging. Magn Reson Med 2023; 89:1469-1480. [PMID: 36420920 PMCID: PMC10099388 DOI: 10.1002/mrm.29545] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Revised: 10/21/2022] [Accepted: 11/14/2022] [Indexed: 11/25/2022]
Abstract
PURPOSE The diffusion-weighted SPLICE (split acquisition of fast spin-echo signals) sequence employs split-echo rapid acquisition with relaxation enhancement (RARE) readout to provide images almost free of geometric distortions. However, due to the varying T 2 $$ {}_2 $$ -weighting during k-space traversal, SPLICE suffers from blurring. This work extends a method for controlling the spatial point spread function (PSF) while optimizing the signal-to-noise ratio (SNR) achieved by adjusting the flip angles in the refocusing pulse train of SPLICE. METHODS An algorithm based on extended phase graph (EPG) simulations optimizes the flip angles by maximizing SNR for a flexibly chosen predefined target PSF that describes the desired k-space density weighting and spatial resolution. An optimized flip angle scheme and a corresponding post-processing correction filter which together achieve the target PSF was tested by healthy subject brain imaging using a clinical 1.5 T scanner. RESULTS Brain images showed a clear and consistent improvement over those obtained with a standard constant flip angle scheme. SNR was increased and apparent diffusion coefficient estimates were more accurate. For a modified Hann k-space weighting example, considerable benefits resulted from acquisition weighting by flip angle control. CONCLUSION The presented flexible method for optimizing SPLICE flip angle schemes offers improved MR image quality of geometrically accurate diffusion-weighted images that makes the sequence a strong candidate for radiotherapy planning or stereotactic surgery.
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Affiliation(s)
- Sofie Rahbek
- Department of Health Technology, Technical University of Denmark, Lyngby, Denmark
| | - Tim Schakel
- Department of Radiotherapy, University Medical Center Utrecht, Utrecht, Netherlands
| | - Faisal Mahmood
- Laboratory of Radiation Physics, Department of Oncology, Odense University Hospital, Odense, Denmark.,Department of Clinical Research, University of Southern Denmark, Odense, Denmark
| | - Kristoffer H Madsen
- Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital, Hvidovre, Denmark.,Department of Applied Mathematics and Computer Science, Technical University of Denmark, Lyngby, Denmark
| | | | - Lars G Hanson
- Department of Health Technology, Technical University of Denmark, Lyngby, Denmark.,Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital, Hvidovre, Denmark
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Shang Y, Liu J, Liu Y, Zhang B, Wu X, Zhang L, Tong W, Hui H, Tian J. Anisotropic edge-preserving network for resolution enhancement in unidirectional Cartesian magnetic particle imaging. Phys Med Biol 2023; 68. [PMID: 36689774 DOI: 10.1088/1361-6560/acb584] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Accepted: 01/23/2023] [Indexed: 01/24/2023]
Abstract
Objective. Magnetic particle imaging (MPI) is a novel imaging modality. It is crucial to acquire accurate localization of the superparamagnetic iron oxide nanoparticles distributions in MPI. However, the spatial resolution of unidirectional Cartesian trajectory MPI exhibits anisotropy, which blurs the boundaries of MPI images and makes precise localization difficult. In this paper, we propose an anisotropic edge-preserving network (AEP-net) to alleviate the anisotropic resolution of MPI.Methods. AEP-net resolve the resolution anisotropy by constructing an asymmertic convolution. To recover the edge information, we design the uncertainty region module. In addition, we evaluated the performance of the proposed AEP-net model by using simulations and experimental data.Results. The results show that the AEP-net model alleviates the anisotropy of the unidirectional Cartesian trajectory and preserves edge details in the MPI image. By comparing the visualization results and the metrics, we demonstrate that our method is superior to other methods.Significance. The proposed method produces accurate visualization in unidirectional Cartesian devices and promotes accurate quantization, which promote the biomedical applications using MPI.
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Affiliation(s)
- Yaxin Shang
- School of Computer and Information Technology, Beijing Jiaotong University, Beijing, 100044, People's Republic of China
| | - Jie Liu
- School of Computer and Information Technology, Beijing Jiaotong University, Beijing, 100044, People's Republic of China
| | - Yanjun Liu
- School of Biological Science and Medical Engineering, Beihang University, Beijing, 100191, People's Republic of China
| | - Bo Zhang
- School of Biological Science and Medical Engineering, Beihang University, Beijing, 100191, People's Republic of China
| | - Xiangjun Wu
- School of Biological Science and Medical Engineering, Beihang University, Beijing, 100191, People's Republic of China
| | - Liwen Zhang
- CAS Key Laboratory of Molecular Imaging, Beijing Key Laboratory of Molecular Imaging, Institute of Automation, Beijing, 100190, People's Republic of China.,The University of Chinese Academy of Sciences, Beijing, 100080, People's Republic of China
| | - Wei Tong
- Senior Department of Cardiology, the Sixth Medical Center of PLA General Hospital, Beijing, 100036, People's Republic of China
| | - Hui Hui
- CAS Key Laboratory of Molecular Imaging, Beijing Key Laboratory of Molecular Imaging, Institute of Automation, Beijing, 100190, People's Republic of China.,The University of Chinese Academy of Sciences, Beijing, 100080, People's Republic of China
| | - Jie Tian
- CAS Key Laboratory of Molecular Imaging, Beijing Key Laboratory of Molecular Imaging, Institute of Automation, Beijing, 100190, People's Republic of China.,Beijing Advanced Innovation Center for Big Data-Based Precision Medicine, School of Engineering Medicine, Beihang University, Beijing, 100191, People's Republic of China
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In MH, Kang D, Jo HJ, Yarach U, Meyer NK, Trzasko JD, Huston J, Bernstein MA, Shu Y. Minimizing susceptibility-induced BOLD sensitivity loss in multi-band accelerated fMRI using point spread function mapping and gradient reversal. Phys Med Biol 2023; 68. [PMID: 36549001 PMCID: PMC10157724 DOI: 10.1088/1361-6560/acae14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Accepted: 12/22/2022] [Indexed: 12/24/2022]
Abstract
Objective. Interleaved reverse-gradient fMRI (RG-fMRI) with a point-spread-function (PSF) mapping-based distortion correction scheme has the potential to minimize signal loss in echo-planar-imaging (EPI). In this work, the RG-fMRI is further improved by imaging protocol optimization and application of reverse Fourier acquisition.Approach. Multi-band imaging was adapted for RG-fMRI to improve the temporal and spatial resolution. To better understand signal dropouts in forward and reverse EPIs, a simple theoretical relationship between echo shift and geometric distortion was derived and validated by the reliable measurements using PSF mapping method. After examining practical imaging protocols for RG-fMRI in three subjects on both a conventional whole-body and a high-performance compact 3 T, the results were compared and the feasibility to further improve the RG-fMRI scheme were explored. High-resolution breath-holding RG-fMRI was conducted with nine subjects on the compact 3 T and the fMRI reliability improvement in high susceptibility brain regions was demonstrated. Finally, reverse Fourier acquisition was applied to RG-fMRI, and its benefit was assessed by a simulation study based on the breath-holding RG-fMRI data.Main results. The temporal and spatial resolution of the multi-band RG-fMRI became feasible for whole-brain fMRI. Echo shift measurements from PSF mapping well estimated signal dropout effects in the EPI pair and were useful to further improve the RG-fMRI scheme. Breath-holding RG-fMRI demonstrated improved fMRI reliability in high susceptibility brain regions. Reverse partial Fourier acquisition omitting the late echoes could further improve the temporal or spatial resolution for RG-fMRI without noticeable signal degradation and spatial resolution loss.Significance. With the improved imaging scheme, RG-fMRI could reliably investigate the functional mechanisms of the human brain in the temporal and frontal areas suffering from susceptibility-induced functional sensitivity loss.
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Affiliation(s)
- Myung-Ho In
- Department of Radiology, Mayo Clinic, Rochester, Minnesota, United States of America
| | - Daehun Kang
- Department of Radiology, Mayo Clinic, Rochester, Minnesota, United States of America
| | - Hang Joon Jo
- Department of Physiology, College of Medicine, Hanyang University, Seoul, Republic of Korea
| | - Uten Yarach
- Department of Radiologic Technology, Faculty of Associated Medical Sciences, Chiang Mai University, Chiang Mai, Thailand
| | - Nolan K Meyer
- Department of Radiology, Mayo Clinic, Rochester, Minnesota, United States of America.,Mayo Clinic Graduate School of Biomedical Sciences, Mayo Clinic, Rochester, MN, United States of America
| | - Joshua D Trzasko
- Department of Radiology, Mayo Clinic, Rochester, Minnesota, United States of America
| | - John Huston
- Department of Radiology, Mayo Clinic, Rochester, Minnesota, United States of America
| | - Matt A Bernstein
- Department of Radiology, Mayo Clinic, Rochester, Minnesota, United States of America
| | - Yunhong Shu
- Department of Radiology, Mayo Clinic, Rochester, Minnesota, United States of America
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Emmerich L, Ohlendorf A, Leube A, Suchkov N, Wahl S. Development and Testing of a Compact Autorefractor Based on Double-Pass Imaging. Sensors (Basel) 2022; 23:362. [PMID: 36616960 PMCID: PMC9823743 DOI: 10.3390/s23010362] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/11/2022] [Revised: 12/05/2022] [Accepted: 12/10/2022] [Indexed: 06/17/2023]
Abstract
Autorefraction is an objective way to determine the refractive error of the eye, without the need for feedback by the patient or a well-educated practitioner. To make refractive measurements more accessible in the background of the growing prevalence of myopia, a compact autorefractor was built, containing only few optical components and relying on double-pass imaging and the physical properties of the point-spread function and digital image processing instead. A method was developed to analyze spherical defocus as well as the defocus and angle of astigmatism. The device was tested using calibrator eye models in a range of ± 15 D spherical defocus and -3 D astigmatic defocus. Reliable results could be achieved across the whole measurement range, with only a small increase in deviation toward high values of refractive errors, showing the feasibility of a PSF-based approach for a compact and low-cost solution for objective measurements of refractive error.
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Affiliation(s)
- Linus Emmerich
- Institute for Ophthalmic Research, Eberhard Karls University Tuebingen, Elfriede-Aulhorn-Str. 7, 72076 Tuebingen, Germany
| | - Arne Ohlendorf
- Institute for Ophthalmic Research, Eberhard Karls University Tuebingen, Elfriede-Aulhorn-Str. 7, 72076 Tuebingen, Germany
- Carl Zeiss Vision International GmbH, Turnstr. 27, 73430 Aalen, Germany
| | - Alexander Leube
- Institute for Ophthalmic Research, Eberhard Karls University Tuebingen, Elfriede-Aulhorn-Str. 7, 72076 Tuebingen, Germany
- Carl Zeiss Vision International GmbH, Turnstr. 27, 73430 Aalen, Germany
| | - Nikolai Suchkov
- Institute for Ophthalmic Research, Eberhard Karls University Tuebingen, Elfriede-Aulhorn-Str. 7, 72076 Tuebingen, Germany
| | - Siegfried Wahl
- Institute for Ophthalmic Research, Eberhard Karls University Tuebingen, Elfriede-Aulhorn-Str. 7, 72076 Tuebingen, Germany
- Carl Zeiss Vision International GmbH, Turnstr. 27, 73430 Aalen, Germany
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Ahrari S, Zaragori T, Bros M, Oster J, Imbert L, Verger A. Implementing the Point Spread Function Deconvolution for Better Molecular Characterization of Newly Diagnosed Gliomas: A Dynamic 18F-FDOPA PET Radiomics Study. Cancers (Basel) 2022; 14:cancers14235765. [PMID: 36497245 PMCID: PMC9738921 DOI: 10.3390/cancers14235765] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Revised: 11/10/2022] [Accepted: 11/17/2022] [Indexed: 11/25/2022] Open
Abstract
Purpose: This study aims to investigate the effects of applying the point spread function deconvolution (PSFd) to the radiomics analysis of dynamic L-3,4-dihydroxy-6-[18F]-fluoro-phenyl-alanine (18F-FDOPA) positron emission tomography (PET) images, to non-invasively identify isocitrate dehydrogenase (IDH) mutated and/or 1p/19q codeleted gliomas. Methods: Fifty-seven newly diagnosed glioma patients underwent dynamic 18F-FDOPA imaging on the same digital PET system. All images were reconstructed with and without PSFd. An L1-penalized (Lasso) logistic regression model, with 5-fold cross-validation and 20 repetitions, was trained with radiomics features extracted from the static tumor-to-background-ratio (TBR) and dynamic time-to-peak (TTP) parametric images, as well as a combination of both. Feature importance was assessed using Shapley additive explanation values. Results: The PSFd significantly modified 95% of TBR, but only 79% of TTP radiomics features. Applying the PSFd significantly improved the ability to identify IDH-mutated and/or 1p/19q codeleted gliomas, compared to PET images not processed with PSFd, with respective areas under the curve of 0.83 versus 0.79 and 0.75 versus 0.68 for a combination of static and dynamic radiomics features (p < 0.001). Without the PSFd, four and eight radiomics features contributed to 50% of the model for detecting IDH-mutated and/or 1p/19q codeleted gliomas, respectively. Application of the PSFd reduced this to three and seven contributive radiomics features. Conclusion: Application of the PSFd to dynamic 18F-FDOPA PET imaging significantly improves the detection of molecular parameters in newly diagnosed gliomas, most notably by modifying TBR radiomics features.
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Affiliation(s)
- Shamimeh Ahrari
- Imagerie Adaptative Diagnostique et Interventionnelle, Institut National de la Santé et de la Recherche Médicale U1254, Université de Lorraine, F-54000 Nancy, France
- Nancyclotep Imaging Platform, Université de Lorraine, F-54000 Nancy, France
| | - Timothée Zaragori
- Imagerie Adaptative Diagnostique et Interventionnelle, Institut National de la Santé et de la Recherche Médicale U1254, Université de Lorraine, F-54000 Nancy, France
- Nancyclotep Imaging Platform, Université de Lorraine, F-54000 Nancy, France
| | - Marie Bros
- Department of Nuclear Medicine, Centre Hospitalier Régional Universitaire de Nancy, F-54000 Nancy, France
| | - Julien Oster
- Imagerie Adaptative Diagnostique et Interventionnelle, Institut National de la Santé et de la Recherche Médicale U1254, Université de Lorraine, F-54000 Nancy, France
| | - Laetitia Imbert
- Imagerie Adaptative Diagnostique et Interventionnelle, Institut National de la Santé et de la Recherche Médicale U1254, Université de Lorraine, F-54000 Nancy, France
- Nancyclotep Imaging Platform, Université de Lorraine, F-54000 Nancy, France
- Department of Nuclear Medicine, Centre Hospitalier Régional Universitaire de Nancy, F-54000 Nancy, France
| | - Antoine Verger
- Imagerie Adaptative Diagnostique et Interventionnelle, Institut National de la Santé et de la Recherche Médicale U1254, Université de Lorraine, F-54000 Nancy, France
- Nancyclotep Imaging Platform, Université de Lorraine, F-54000 Nancy, France
- Department of Nuclear Medicine, Centre Hospitalier Régional Universitaire de Nancy, F-54000 Nancy, France
- Correspondence:
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Sekehravani EA, Leone G, Pierri R. Performance of the Linear Model Scattering of 2D Full Object with Limited Data. Sensors (Basel) 2022; 22:s22103868. [PMID: 35632277 PMCID: PMC9147966 DOI: 10.3390/s22103868] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Revised: 05/17/2022] [Accepted: 05/19/2022] [Indexed: 05/14/2023]
Abstract
Inverse scattering problems stand at the center of many important imaging applications, such as geophysical explorations, radar imaging, and synthetic-aperture radar (SAR). Several methods have been proposed to solve them when the full data are available, usually providing satisfactory reconstructions. However, it is impossible to acquire the full data in many practical circumstances, such as target detection and ground penetrating radar (GPR); consequently, only limited data are available. Thus, this paper focuses on the mathematical analysis and some numerical simulations to estimate the achievable resolution in reconstructing an object from the knowledge of the scattered far-field when only limited data are available, with multi-view excitations at a single frequency. We focus on 2D full rectangular geometry as the investigation domain (ID). We also examine the number of degrees of freedom (NDF) and evaluate the point spread function (PSF). In particular, the NDF of the considered geometry can be estimated analytically. An approximated closed-form evaluation of the PSF is recalled, discussed, and compared with the exact one. Moreover, receiving, transmission, and angle sensing modes are considered to apply the analysis to more realistic scenarios to highlight the difference between the corresponding NDF and the resulting resolution performances. Finally, interesting numerical applications of the resolution analysis for the localization of a collection of point-like scatterers are presented to illustrate how it matches the expectations.
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14
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Zhu D, Schär M, Qin Q. Ultrafast B1 mapping with RF-prepared 3D FLASH acquisition: Correcting the bias due to T 1 -induced k-space filtering effect. Magn Reson Med 2022; 88:757-769. [PMID: 35381114 PMCID: PMC9232926 DOI: 10.1002/mrm.29247] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 03/06/2022] [Accepted: 03/07/2022] [Indexed: 01/25/2023]
Abstract
Purpose The traditional radiofrequency (RF)‐prepared B1 mapping technique consists of one scan with an RF preparation module for flip angle‐encoding and a second scan without this module for normalizing. To reduce the T1‐induced k‐space filtering effect, this method is limited to 2D FLASH acquisition with a two‐parameter method. A novel 3D RF‐prepared three‐parameter method for ultrafast B1‐mapping is proposed to correct the T1‐induced quantification bias. Theory The point spread function analysis of FLASH shows that the prepared longitudinal magnetization before the FLASH acquisition and the image signal obeys a linear (not proportional) relationship. The intercept of the linear function causes the quantification bias and can be captured by a third saturated scan. Methods Using the 2D double‐angle method (DAM) as the reference, a 3D RF‐prepared three‐parameter protocol with 9 s duration was compared with the two‐parameter method, as well as the saturated DAM (SDAM) method, the dual refocusing echo acquisition mode (DREAM) method, and the actual flip‐angle imaging (AFI) method, for B1 mapping of brain, breast, and abdomen with different orientations and shim settings at 3T. Results The 3D RF‐prepared three‐parameter method with complex‐subtraction delivered consistently lower RMS error, error mean, error standard deviation, and higher concordance correlation coefficients values than the two‐parameter method, the three‐parameter method with magnitude‐subtraction, the multi‐slice DREAM and the 3D AFI, and were close to the results of 2D or multi‐slice SDAM. Conclusion The proposed ultrafast 3D RF‐prepared three‐parameter method with complex‐subtraction was demonstrated with high accuracy for B1 mapping of brain, breast, and abdomen.
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Affiliation(s)
- Dan Zhu
- F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA.,The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Michael Schär
- The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Qin Qin
- F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA.,The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, USA
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15
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Zhang S, Chen X, Zu Y, Rao P. A Dynamic Imaging Simulation Method of Infrared Aero-Optical Effect Based on Continuously Varying Gaussian Superposition Model. Sensors (Basel) 2022; 22:s22041616. [PMID: 35214520 PMCID: PMC8874892 DOI: 10.3390/s22041616] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Revised: 02/04/2022] [Accepted: 02/14/2022] [Indexed: 02/05/2023]
Abstract
Aero-optical effect correction has become a crucial issue in airborne infrared imaging. However, it is impractical to test the correction algorithm using flight tests and numerical simulation because of its high cost. This study proposes a dynamic imaging simulation method for the infrared aero-optical effect based on a continuously varying Gaussian superposition model. The influence of infrared image degradation under different high-speed aerodynamic flow fields was investigated in detail. A continuously varying Gaussian superposition model was established for flight speed, altitude, and attitude. A dynamic infrared scene simulation model was constructed. Experimental results show that the proposed method can realistically simulate actual aero-optical effects of any flight case. Moreover, it can simulate continuous frames of aerodynamically degraded infrared images. The method uses a simpler model than numerical simulation and provides more data for multitype tasks.
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Affiliation(s)
- Shuyuan Zhang
- Key Laboratory of Intelligent Infrared Perception, Chinese Academy of Sciences, Shanghai 200083, China; (S.Z.); (X.C.)
- Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xin Chen
- Key Laboratory of Intelligent Infrared Perception, Chinese Academy of Sciences, Shanghai 200083, China; (S.Z.); (X.C.)
- Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083, China
- Department of Aeronautics and Astronautics, Fudan University, Shanghai 200433, China;
| | - Yingqing Zu
- Department of Aeronautics and Astronautics, Fudan University, Shanghai 200433, China;
| | - Peng Rao
- Key Laboratory of Intelligent Infrared Perception, Chinese Academy of Sciences, Shanghai 200083, China; (S.Z.); (X.C.)
- Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083, China
- Correspondence:
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16
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Spaide RF, Otto T, Caujolle S, Kübler J, Aumann S, Fischer J, Reisman C, Spahr H, Lessmann A. Lateral Resolution of a Commercial Optical Coherence Tomography Instrument. Transl Vis Sci Technol 2022; 11:28. [PMID: 35044444 PMCID: PMC8787587 DOI: 10.1167/tvst.11.1.28] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Accepted: 12/18/2021] [Indexed: 11/24/2022] Open
Abstract
Purpose The lateral resolution of an optical coherence tomography (OCT) instrument was considered to be equal to the illumination spot size on the retina. To evaluate the potential lateral resolution of the Spectralis OCT, an instrument calculated to have a 14 µm resolution. Methods The lateral point spread function (PSF) was evaluated using diamond abrasive powder 0 to 1 µm in diameter in silicone elastomer and a validated target with 800 nm FeO particles in urethane. The amplitude transfer function was calculated from human OCT images. Finally, resolution was measured using the 1951 USAF target. Results Measurement of the lateral PSF from 1215 diamond particle images yielded a full-width half maximum (FWHM) to be 5.11 µm and for 732 FeO particles, 4.9 µm. From the amplitude transfer function, the FWHM of the diffraction limited PSF was calculated to be 5.0 µm. The USAF target imaging showed a lateral resolution of 4.6 µm. Conclusions Although a calculation of the spot size of the illumination beam was reported in the past as the lateral resolution of the OCT instrument, the actual lateral resolution is better by a factor of at least 2.5 times. The clinically used A-scan spacing was derived from the calculated, and not the true resolution, and results in under sampling. This set of findings likely apply to all commercial clinical instruments. Translational Relevance The scan density parameters of past and present commercial OCT instruments were based on earlier translational concepts, which now appear to have been incorrect.
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Affiliation(s)
- Richard F. Spaide
- Vitreous Retina, Macula Consultants of New York, New York, New York, USA
| | - Tilman Otto
- Heidelberg Engineering GmbH, Heidelberg, Germany
| | | | | | - Silke Aumann
- Heidelberg Engineering GmbH, Heidelberg, Germany
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17
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Fan W, Dehghani H, Eggebrecht AT. Investigation of effect of modulation frequency on high-density diffuse optical tomography image quality. Neurophotonics 2021; 8:045002. [PMID: 34849379 PMCID: PMC8612746 DOI: 10.1117/1.nph.8.4.045002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Accepted: 11/04/2021] [Indexed: 05/16/2023]
Abstract
Significance: By incorporating multiple overlapping functional near-infrared spectroscopy (fNIRS) measurements, high-density diffuse optical tomography (HD-DOT) images human brain function with fidelity comparable to functional magnetic resonance imaging (fMRI). Previous work has shown that frequency domain high-density diffuse optical tomography (FD-HD-DOT) may further improve image quality over more traditional continuous wave (CW) HD-DOT. Aim: The effects of modulation frequency on image quality as obtainable with FD-HD-DOT is investigated through simulations with a realistic noise model of functional activations in human head models, arising from 11 source modulation frequencies between CW and 1000 MHz. Approach: Simulations were performed using five representative head models with an HD regular grid of 158 light sources and 166 detectors and an empirically derived noise model. Functional reconstructions were quantitatively assessed with multiple image quality metrics including the localization error (LE), success rate, full width at half maximum, and full volume at half maximum (FVHM). All metrics were evaluated against CW-based models. Results: Compared to CW, localization accuracy is improved by >40% throughout brain depths of 13 to 25 mm below the surface with 300 to 500 MHz modulation frequencies. Additionally, the reliable field of view in brain tissue is enlarged by 35% to 48% within an optimal frequency of 300 MHz after considering realistic noise, depending on the dynamic range of the system. Conclusions: These results point to the tremendous opportunities in further development of high bandwidth FD-HD-DOT system hardware for applications in human brain mapping.
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Affiliation(s)
- Weihao Fan
- Washington University, Department of Physics, St. Louis, Missouri, United States
| | - Hamid Dehghani
- University of Birmingham, School of Computer Science, Birmingham, United Kingdom
| | - Adam T. Eggebrecht
- Washington University School of Medicine, Mallinckrodt Institute of Radiology, St. Louis, Missouri, United States
- Washington University, Department of Biomedical Engineering, St. Louis, Missouri, United States
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18
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Huang N, Deng Z, Hu Z, Mei J, Zhao S, Wu X, Jia Z, Liu Y, Wang J, Ye Q, Tian J. A spatial resolution evaluation method of endoscopic optical coherence tomography system using the annular phantom. J Biophotonics 2021; 14:e202100035. [PMID: 33991071 DOI: 10.1002/jbio.202100035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 04/11/2021] [Accepted: 05/11/2021] [Indexed: 06/12/2023]
Abstract
As an important biomedical imaging method, endoscopic optical coherence tomography (OCT) is necessary to check its performance regularly. The ordinary plane phantoms are only able to evaluate part of image tangent to the probe. In this research, a spatial resolution estimate method of the endoscope OCT system is proposed. The annular phantom, made by uniformly distributing golden scattered microparticles in polydimethylsiloxane (PDMS), can provide dynamic scanning imaging evaluation of endoscopic OCT system, closer to its actual working status. The point spread function analysis method is used to analyze the imaging results of the annular phantom with the endoscopic OCT system. And many scattered particles are statistically analyzed to determine the spatial resolution of the endoscope OCT system. The method is low in cost, simple and convenient. It is valuable for the development of test standards for endoscope OCT systems.
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Affiliation(s)
- Ningning Huang
- The Key Laboratory of Weak-Light Nonlinear Photonics, MOE, School of Physics and TEDA Applied Physics School, Nankai University, Tianjin, China
| | - Zhichao Deng
- The Key Laboratory of Weak-Light Nonlinear Photonics, MOE, School of Physics and TEDA Applied Physics School, Nankai University, Tianjin, China
- The 2011 Project Collaborative Innovation Center for Biological Therapy, Nankai University, Tianjin, China
| | - Zhixiong Hu
- Division of Medical and Biological Measurement, National Institute of Metrology, Beijing, China
| | - Jianchun Mei
- The Key Laboratory of Weak-Light Nonlinear Photonics, MOE, School of Physics and TEDA Applied Physics School, Nankai University, Tianjin, China
| | - Shiyong Zhao
- The Tianjin Horimed Medical Technology Co., Ltd, Tianjin, China
| | - Xining Wu
- The Tianjin Horimed Medical Technology Co., Ltd, Tianjin, China
| | - Zongnan Jia
- The Tianjin Horimed Medical Technology Co., Ltd, Tianjin, China
| | - Yuyan Liu
- Tianjin Eye Hospital, Nankai University affiliated Eye Hospital, Clinical College of Ophthalmology Tianjin Medical University, Tianjin, China
| | - Jin Wang
- The Key Laboratory of Weak-Light Nonlinear Photonics, MOE, School of Physics and TEDA Applied Physics School, Nankai University, Tianjin, China
- The 2011 Project Collaborative Innovation Center for Biological Therapy, Nankai University, Tianjin, China
| | - Qing Ye
- The Key Laboratory of Weak-Light Nonlinear Photonics, MOE, School of Physics and TEDA Applied Physics School, Nankai University, Tianjin, China
- The 2011 Project Collaborative Innovation Center for Biological Therapy, Nankai University, Tianjin, China
| | - Jianguo Tian
- The Key Laboratory of Weak-Light Nonlinear Photonics, MOE, School of Physics and TEDA Applied Physics School, Nankai University, Tianjin, China
- The 2011 Project Collaborative Innovation Center for Biological Therapy, Nankai University, Tianjin, China
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Doyen M, Mairal E, Bordonne M, Zaragori T, Roch V, Imbert L, Verger A. Effect of Point Spread Function Deconvolution in Reconstruction of Brain 18F-FDG PET Images on the Diagnostic Thinking Efficacy in Alzheimer's Disease. Front Med (Lausanne) 2021; 8:721551. [PMID: 34395486 PMCID: PMC8358179 DOI: 10.3389/fmed.2021.721551] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Accepted: 07/06/2021] [Indexed: 11/22/2022] Open
Abstract
Purpose: This study aims to determine the effect of applying Point Spread Function (PSF) deconvolution, which is known to improve contrast and spatial resolution in brain 18F-FDG PET images, to the diagnostic thinking efficacy in Alzheimer's disease (AD). Methods: We compared Hoffman 3-D brain phantom images reconstructed with or without PSF. The effect of PSF deconvolution on AD diagnostic clinical performance was determined from digital brain 18F-FDG PET images of AD (n = 38) and healthy (n = 35) subjects compared to controls (n = 36). Performances were assessed with SPM at the group level (p < 0.001 for the voxel) and at the individual level by visual interpretation of SPM T-maps (p < 0.005 for the voxel) by the consensual analysis of three experienced raters. Results: A mix of large hypometabolic (1,483cm3, mean value of −867 ± 492 Bq/ml) and intense hypermetabolic (902 cm3, mean value of 1,623 ± 1,242 Bq/ml) areas was observed in the PSF compared to the no PSF phantom images. Significant hypometabolic areas were observed in the AD group compared to the controls, for reconstructions with and without PSF (respectively 23.7 and 26.2 cm3), whereas no significant hypometabolic areas were observed when comparing the group of healthy subjects to the control group. At the individual level, no significant differences in diagnostic performances for discriminating AD were observed visually (sensitivity of 89 and 92% for reconstructions with and without PSF respectively, similar specificity of 74%). Conclusion: Diagnostic thinking efficacy performances for diagnosing AD are similar for 18F-FDG PET images reconstructed with or without PSF.
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Affiliation(s)
- Matthieu Doyen
- Université de Lorraine, IADI, INSERM U1254 and Nancyclotep Imaging Platform, Nancy, France
| | - Elise Mairal
- Department of Nuclear Medicine, Université de Lorraine, CHRU Nancy, Nancy, France
| | - Manon Bordonne
- Department of Nuclear Medicine, Université de Lorraine, CHRU Nancy, Nancy, France
| | - Timothée Zaragori
- Université de Lorraine, IADI, INSERM U1254 and Nancyclotep Imaging Platform, Nancy, France
| | - Véronique Roch
- Université de Lorraine, IADI, INSERM U1254 and Nancyclotep Imaging Platform, Nancy, France
| | - Laetitia Imbert
- Université de Lorraine, IADI, INSERM U1254 and Nancyclotep Imaging Platform, Nancy, France.,Department of Nuclear Medicine, Université de Lorraine, CHRU Nancy, Nancy, France
| | - Antoine Verger
- Université de Lorraine, IADI, INSERM U1254 and Nancyclotep Imaging Platform, Nancy, France.,Department of Nuclear Medicine, Université de Lorraine, CHRU Nancy, Nancy, France
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Makūnaitė M, Jurkonis R, Lukoševičius A, Baranauskas M. Main Uncertainties in the RF Ultrasound Scanning Simulation of the Standard Ultrasound Phantoms. Sensors (Basel) 2021; 21:s21134420. [PMID: 34203320 PMCID: PMC8271890 DOI: 10.3390/s21134420] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Revised: 06/23/2021] [Accepted: 06/25/2021] [Indexed: 12/13/2022]
Abstract
Ultrasound echoscopy technologies are continuously evolving towards new modalities including quantitative parameter imaging, elastography, 3D scanning, and others. The development and analysis of new methods and algorithms require an adequate digital simulation of radiofrequency (RF) signal transformations. The purpose of this paper is the quantitative evaluation of RF signal simulation uncertainties in resolution and contrast reproduction with the model of a phased array transducer. The method is based on three types of standard physical phantoms. Digital 3D models of those phantoms are composed of point scatterers representing the weak backscattering of the background material and stronger backscattering from inclusions. The simulation results of echoscopy with sector scanning transducer by Field II software are compared with the RF output of the Ultrasonix scanner after scanning standard phantoms with 2.5 MHz phased array. The quantitative comparison of axial, lateral, and elevation resolutions have shown uncertainties from 9 to 22% correspondingly. The echoscopy simulation with two densities of scatterers is compared with contrast phantom imaging on the backscattered RF signals and B-scan reconstructed image, showing that the main sources of uncertainties limiting the echoscopy RF signal simulation adequacy are an insufficient knowledge of the scanner and phantom’s parameters. The attempt made for the quantitative evaluation of simulation uncertainties shows both problems and the potential of echoscopy simulation in imaging technology developments. The analysis presented could be interesting for researchers developing quantitative ultrasound imaging and elastography technologies looking for simulated raw RF signals comparable to those obtained from real ultrasonic scanning.
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21
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Tian C, Zhang C, Zhang H, Xie D, Jin Y. Spatial resolution in photoacoustic computed tomography. Rep Prog Phys 2021; 84:036701. [PMID: 33434890 DOI: 10.1088/1361-6633/abdab9] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Accepted: 01/12/2021] [Indexed: 06/12/2023]
Abstract
Photoacoustic computed tomography (PACT) is a novel biomedical imaging modality and has experienced fast developments in the past two decades. Spatial resolution is an important criterion to measure the imaging performance of a PACT system. Here we survey state-of-the-art literature on the spatial resolution of PACT and analyze resolution degradation models from signal generation, propagation, reception, to image reconstruction. Particularly, the impacts of laser pulse duration, acoustic attenuation, acoustic heterogeneity, detector bandwidth, detector aperture, detector view angle, signal sampling, and image reconstruction algorithms are reviewed and discussed. Analytical expressions of point spread functions related to these impacting factors are summarized based on rigorous mathematical formulas. State-of-the-art approaches devoted to enhancing spatial resolution are also reviewed. This work is expected to elucidate the concept of spatial resolution in PACT and inspire novel image quality enhancement techniques.
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Affiliation(s)
- Chao Tian
- Department of Precision Machinery and Precision Instrumentation, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China
- Key Laboratory of Precision Scientific Instrumentation of Anhui Higher Education Institutes, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China
| | - Chenxi Zhang
- Department of Precision Machinery and Precision Instrumentation, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China
- Key Laboratory of Precision Scientific Instrumentation of Anhui Higher Education Institutes, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China
| | - Haoran Zhang
- Department of Precision Machinery and Precision Instrumentation, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China
- Key Laboratory of Precision Scientific Instrumentation of Anhui Higher Education Institutes, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China
| | - Dan Xie
- Department of Precision Machinery and Precision Instrumentation, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China
- Key Laboratory of Precision Scientific Instrumentation of Anhui Higher Education Institutes, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China
| | - Yi Jin
- Department of Precision Machinery and Precision Instrumentation, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China
- Key Laboratory of Precision Scientific Instrumentation of Anhui Higher Education Institutes, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China
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22
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Ahmad A, Frindel C, Rousseau D. Detecting Differences of Fluorescent Markers Distribution in Single Cell Microscopy: Textural or Pointillist Feature Space? Front Robot AI 2021; 7:39. [PMID: 33501207 PMCID: PMC7805927 DOI: 10.3389/frobt.2020.00039] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Accepted: 03/09/2020] [Indexed: 12/22/2022] Open
Abstract
We consider the detection of change in spatial distribution of fluorescent markers inside cells imaged by single cell microscopy. Such problems are important in bioimaging since the density of these markers can reflect the healthy or pathological state of cells, the spatial organization of DNA, or cell cycle stage. With the new super-resolved microscopes and associated microfluidic devices, bio-markers can be detected in single cells individually or collectively as a texture depending on the quality of the microscope impulse response. In this work, we propose, via numerical simulations, to address detection of changes in spatial density or in spatial clustering with an individual (pointillist) or collective (textural) approach by comparing their performances according to the size of the impulse response of the microscope. Pointillist approaches show good performances for small impulse response sizes only, while all textural approaches are found to overcome pointillist approaches with small as well as with large impulse response sizes. These results are validated with real fluorescence microscopy images with conventional resolution. This, a priori non-intuitive result in the perspective of the quest of super-resolution, demonstrates that, for difference detection tasks in single cell microscopy, super-resolved microscopes may not be mandatory and that lower cost, sub-resolved, microscopes can be sufficient.
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Affiliation(s)
- Ali Ahmad
- Laboratoire Angevin de Recherche en Ingénierie des Systèmes, UMR INRAE IRHS, Université d'Angers, Angers, France.,Centre de Recherche en Acquisition et Traitement de l'Image pour la Santé, CNRS UMR 5220-INSERM U1206, Université Lyon 1, INSA de Lyon, Lyon, France
| | - Carole Frindel
- Centre de Recherche en Acquisition et Traitement de l'Image pour la Santé, CNRS UMR 5220-INSERM U1206, Université Lyon 1, INSA de Lyon, Lyon, France
| | - David Rousseau
- Laboratoire Angevin de Recherche en Ingénierie des Systèmes, UMR INRAE IRHS, Université d'Angers, Angers, France
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23
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Lee Y, Wilm BJ, Brunner DO, Gross S, Schmid T, Nagy Z, Pruessmann KP. On the signal-to-noise ratio benefit of spiral acquisition in diffusion MRI. Magn Reson Med 2020; 85:1924-1937. [PMID: 33280160 DOI: 10.1002/mrm.28554] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 09/15/2020] [Accepted: 09/22/2020] [Indexed: 12/20/2022]
Abstract
PURPOSE Spiral readouts combine several favorable properties that promise superior net sensitivity for diffusion imaging. The purpose of this study is to verify the signal-to-noise ratio (SNR) benefit of spiral acquisition in comparison with current echo-planar imaging (EPI) schemes. METHODS Diffusion-weighted in vivo brain data from three subjects were acquired with a single-shot spiral sequence and several variants of single-shot EPI, including full-Fourier and partial-Fourier readouts as well as different diffusion-encoding schemes. Image reconstruction was based on an expanded signal model including field dynamics obtained by concurrent field monitoring. The effective resolution of each sequence was matched to that of full-Fourier EPI with 1 mm nominal resolution. SNR maps were generated by determining the noise statistics of the raw data and analyzing the propagation of equivalent synthetic noise through image reconstruction. Using the same approach, maps of noise amplification due to parallel imaging (g-factor) were calculated for different acceleration factors. RESULTS Relative to full-Fourier EPI at b = 0 s/mm2 , spiral acquisition yielded SNR gains of 42-88% and 40-89% in white and gray matter, respectively, depending on the diffusion-encoding scheme. Relative to partial-Fourier EPI, the gains were 36-44% and 34-42%. Spiral g-factor maps exhibited less spatial variation and lower maxima than their EPI counterparts. CONCLUSION Spiral readouts achieve significant SNR gains in the order of 40-80% over EPI in diffusion imaging at 3T. Combining systematic effects of shorter echo time, readout efficiency, and favorable g-factor behavior, similar benefits are expected across clinical and neurosciences uses of diffusion imaging.
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Affiliation(s)
- Yoojin Lee
- Institute for Biomedical Engineering, ETH Zurich and University of Zurich, Zurich, Switzerland.,Laboratory for Social and Neural Systems Research, University of Zurich, Zurich, Switzerland
| | - Bertram J Wilm
- Institute for Biomedical Engineering, ETH Zurich and University of Zurich, Zurich, Switzerland
| | - David O Brunner
- Institute for Biomedical Engineering, ETH Zurich and University of Zurich, Zurich, Switzerland
| | - Simon Gross
- Institute for Biomedical Engineering, ETH Zurich and University of Zurich, Zurich, Switzerland
| | - Thomas Schmid
- Institute for Biomedical Engineering, ETH Zurich and University of Zurich, Zurich, Switzerland
| | - Zoltan Nagy
- Laboratory for Social and Neural Systems Research, University of Zurich, Zurich, Switzerland
| | - Klaas P Pruessmann
- Institute for Biomedical Engineering, ETH Zurich and University of Zurich, Zurich, Switzerland
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24
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Abstract
The confocal Raman microscope (CRM) is a powerful tool in analytical science. Image quality is the most important performance indicator of CRM systems. The point spread function (PSF) is one of the most useful tools to evaluate the image quality of microscopic systems. A method based on a point-like object is proposed to measure the PSF of CRM, and the size effect of spherical objects is discussed. A series of phantoms are fabricated by embedding different sizes of polystyrene microspheres into polydimethylsiloxane matrix. The diameters of microspheres are from 0.2 µm to 5 µm. The phantoms are tested by measuring the PSF of a commercial CRM whose nominal lateral resolution is about 1 µm. Results of the PSF are obtained and the accuracy of resolution is used to evaluate the size effect of the microspheres. Experimental results are well consistent with theoretical analysis. The error of the PSF can be decreased by reducing the diameter of the microsphere but meanwhile the signal-to-noise ratio (S/N) will be lowered as well. The proper diameter of microspheres is proposed in consideration of the trade-off between the S/N and the measurement error of the PSF. Results indicate that the method provides a useful approach to measurement of the PSF and the resolution of the CRM.
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Affiliation(s)
- Xiang Ding
- National Institute of Metrology, Beijing, China
| | - Yanzhe Fu
- National Institute of Metrology, Beijing, China
| | - Jiyan Zhang
- National Institute of Metrology, Beijing, China
| | - Yao Hu
- Beijing Key Laboratory for Precision Optoelectronic Measurement Instrument and Technology, School of Optoelectronics, 47833Beijing Institute of Technology, Beijing, China
| | - Shihang Fu
- Beijing Key Laboratory for Precision Optoelectronic Measurement Instrument and Technology, School of Optoelectronics, 47833Beijing Institute of Technology, Beijing, China
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25
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Abstract
Single particle tracking (SPT) has proven to be a powerful technique in studying molecular dynamics in complicated systems. We review its recent development, including three-dimensional (3D) SPT and its applications in probing nanostructures and molecule-surface interactions that are important to analytical chemical processes. Several frequently used 3D SPT techniques are introduced. Especially of interest are those based on point spread function engineering, which are simple in instrumentation and can be easily adapted and used in analytical labs. Corresponding data analysis methods are briefly discussed. We present several important case studies, with a focus on probing mass transport and molecule-surface interactions in confined environments. The presented studies demonstrate the great potential of 3D SPT for understanding fundamental phenomena in confined space, which will enable us to predict basic principles involved in chemical recognition, separation, and analysis, and to optimize mass transport and responses by structural design and optimization.
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Affiliation(s)
- Yaning Zhong
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, USA;
| | - Gufeng Wang
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, USA;
- Department of Chemistry, Georgia State University, Atlanta, Georgia 30303, USA
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26
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Froidevaux R, Weiger M, Rösler MB, Brunner DO, Dietrich BE, Reber J, Pruessmann KP. High-resolution short-T 2 MRI using a high-performance gradient. Magn Reson Med 2020; 84:1933-1946. [PMID: 32176828 DOI: 10.1002/mrm.28254] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Revised: 02/20/2020] [Accepted: 02/20/2020] [Indexed: 12/17/2022]
Abstract
PURPOSE To achieve high resolution in imaging of short-T2 materials and tissues by using a high-performance human-sized gradient insert with strength up to 200 mT/m and 100% duty cycle. METHODS Dedicated short-T2 methodology and hardware are used, such as the pointwise encoding time reduction with radial acquisition (PETRA) technique with modulated excitation pulses, optimized radio-frequency hardware, and a high-performance gradient insert. A theoretical analysis of actual spatial resolution and SNR is provided to support the choice of scan parameters and interpretation of the results. Imaging is performed in resolution phantoms, animal specimen, and human volunteers at both conventional and maximum available gradient strengths and compared using image subtraction. RESULTS Calculations suggest that increasing gradient strength beyond conventional values considerably improves both actual resolution and SNR efficiency in short-T2 imaging. Resolution improvements are confirmed in all investigated samples, in particular 2 mm slots were resolved in a hard-plastic plate with T2 ≈ 10 μs and in vivo musculoskeletal images were acquired at isotropic 200 μm resolution. Expected improvements in signal yield are realized in fine structures benefitting from high resolution but to less extent in regions of low contrast where decay-related blurring leads to signal overlap between neighboring locations. CONCLUSION Strong gradients with high duty cycle enable short-T2 imaging at unprecedentedly high resolution, holding the potential for improving MRI of, eg, bone, tendon, lung, or teeth. Moreover, it allows direct access of tissues with T2 of tens of microseconds such as myelin or collagen.
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Affiliation(s)
- Romain Froidevaux
- Institute for Biomedical Engineering, ETH Zurich and University of Zurich, Zurich, Switzerland
| | - Markus Weiger
- Institute for Biomedical Engineering, ETH Zurich and University of Zurich, Zurich, Switzerland
| | - Manuela B Rösler
- Institute for Biomedical Engineering, ETH Zurich and University of Zurich, Zurich, Switzerland
| | - David O Brunner
- Institute for Biomedical Engineering, ETH Zurich and University of Zurich, Zurich, Switzerland
| | - Benjamin E Dietrich
- Institute for Biomedical Engineering, ETH Zurich and University of Zurich, Zurich, Switzerland
| | - Jonas Reber
- Institute for Biomedical Engineering, ETH Zurich and University of Zurich, Zurich, Switzerland
| | - Klaas P Pruessmann
- Institute for Biomedical Engineering, ETH Zurich and University of Zurich, Zurich, Switzerland
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27
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Nevins MC, Quoi K, Hailstone RK, Lifshin E. Exploring the Parameter Space of Point Spread Function Determination for the Scanning Electron Microscope-Part I: Effect on the Point Spread Function. Microsc Microanal 2019; 25:1167-1182. [PMID: 31452494 DOI: 10.1017/s1431927619014806] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The point spread function (PSF) of the scanning electron microscope (SEM) can be determined using a recently developed nanoparticle calibration method. Many parameters are involved in PSF determination and introduce a previously unstudied amount of uncertainty into the PSF size and shape. Signal type, support material thickness, reference particle size, PSF smoothing (K), and background correction were investigated regarding their effect on the PSF. Experimental data were complemented by CASINO simulations. Differences in detector position between the observed particles and the method's simulated reference particles caused shifting between secondary electron PSFs and backscattered electron PSFs. Support material thickness did not have a practical effect on the PSF at the tested voltages. Uncertainty in reference particle size varied the PSF full width at half maximum (FWHM) within ±0.7 nm at 2σ, with virtually no uncertainty in some cases. K and background correction within a reasonable range of values resulted in PSF FWHM differences within ±0.9 nm, except at 2 kV for K with an upper bound of ±1.9 nm due to increased noise. Tailoring K and background correction case-by-case would result in smaller differences. The interconnection of these parameters may help in future efforts to calculate their best selection.
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Affiliation(s)
- Mandy C Nevins
- Center for Imaging Science, Rochester Institute of Technology, Rochester, NY 14623, USA
| | - Kathryn Quoi
- Nanoscience Constellation of the Colleges of Nanoscience and Engineering, SUNY Polytechnic Institute, Albany, NY 12203, USA
| | - Richard K Hailstone
- Center for Imaging Science, Rochester Institute of Technology, Rochester, NY 14623, USA
| | - Eric Lifshin
- Nanoscience Constellation of the Colleges of Nanoscience and Engineering, SUNY Polytechnic Institute, Albany, NY 12203, USA
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28
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Nevins MC, Hailstone RK, Lifshin E. Exploring the Parameter Space of Point Spread Function Determination for the Scanning Electron Microscope-Part II: Effect on Image Restoration Quality. Microsc Microanal 2019; 25:1183-1194. [PMID: 31466547 DOI: 10.1017/s1431927619014831] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Point spread function (PSF) deconvolution is an attractive software-based technique for resolution improvement in the scanning electron microscope (SEM) because it can restore information which has been blurred by challenging operating conditions. In Part 1, we studied a modern PSF determination method for SEM and explored how various parameters affected the method's ability to accurately estimate the PSF. In Part 2, we extend this exploration to PSF deconvolution for image restoration. The parameters include reference particle size, PSF smoothing (K), background correction, and restoration denoising (λ). Image quality was assessed by visual inspection and Fourier analysis. Overall, PSF deconvolution improved image quality. Low λ enhanced image sharpness at the cost of noise, while high λ created smoother restorations with less detail. λ should be chosen to balance feature preservation and denoising based on the application. Reference particle size within ±0.9 nm and K within a reasonable range had little effect on restoration quality. Restorations using background-corrected PSFs had superior quality compared with using no background correction, but if the correction was too high, the PSF was cut off causing blurrier restorations. Future efforts to automatically determine parameters would remove user guesswork, improve this method's consistency, and maximize interpretability of outputs.
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Affiliation(s)
- Mandy C Nevins
- Center for Imaging Science, Rochester Institute of Technology, Rochester, NY 14623, USA
| | - Richard K Hailstone
- Center for Imaging Science, Rochester Institute of Technology, Rochester, NY 14623, USA
| | - Eric Lifshin
- Nanoscience Constellation of the Colleges of Nanoscience and Engineering, SUNY Polytechnic Institute, Albany, NY 12203, USA
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Lu S, Li R, Yu X, Wang D, Wan M. Delay multiply and sum beamforming method applied to enhance linear-array passive acoustic mapping of ultrasound cavitation. Med Phys 2019; 46:4441-4454. [PMID: 31309568 DOI: 10.1002/mp.13714] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Revised: 06/25/2019] [Accepted: 07/06/2019] [Indexed: 12/25/2022] Open
Abstract
PURPOSE Passive acoustic mapping (PAM) has been proposed as a means of monitoring ultrasound therapy, particularly nonthermal cavitation-mediated applications. In PAM, the most common beamforming algorithm is a delay, sum, and integrate (DSAI) approach. However, using DSAI leads to low-quality images for the case where a narrow-aperture receiving array such as a standard B-mode linear array is used. This study aims to propose an enhanced linear-array PAM algorithm based on delay, multiply, sum, and integrate (DMSAI). METHODS In the proposed algorithm, before summation, the delayed signals are combinatorially coupled and multiplied, which means that the beamformed output of the proposed algorithm is the spatial coherence of received acoustic emissions. We tested the performance of the proposed DMSAI using both simulated and experimental data and compared it with DSAI. The reconstructed cavitation images were evaluated quantitatively by using source location errors between the two algorithms, full width at half maximum (FWHM), size of point spread function (A50 area), signal-to-noise ratio (SNR), and computational time. RESULTS The results of simulations and experiments for single cavitation source show that, by introducing DMSAI, the FWHM and the A50 area are reduced and the SNR is improved compared with those obtained by DSAI. The simulation results for two symmetric or nonsymmetric cavitation sources and multiple cavitation sources show that DMSAI can significantly reduce the A50 area and improve the SNR, therefore improving the detectability of multiple cavitation sources. CONCLUSIONS The results indicate that the proposed DMSAI algorithm outperforms the conventionally used DSAI algorithm. This work may have the potential of providing an appropriate method for ultrasound therapy monitoring.
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Affiliation(s)
- Shukuan Lu
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, Department of Biomedical Engineering, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, 710049, People's Republic of China
| | - Renyan Li
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, Department of Biomedical Engineering, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, 710049, People's Republic of China
| | - Xianbo Yu
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, Department of Biomedical Engineering, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, 710049, People's Republic of China
| | - Diya Wang
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, Department of Biomedical Engineering, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, 710049, People's Republic of China
| | - Mingxi Wan
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, Department of Biomedical Engineering, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, 710049, People's Republic of China
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30
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Agnero MA, Konan K, Tokou ZGCS, Kossonou YTA, Dion BS, Kaduki KA, Zoueu JT. Malaria-Infected Red Blood Cell Analysis through Optical and Biochemical Parameters Using the Transport of Intensity Equation and the Microscope's Optical Properties. Sensors (Basel) 2019; 19:E3045. [PMID: 31295927 PMCID: PMC6678084 DOI: 10.3390/s19143045] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Revised: 06/07/2019] [Accepted: 06/09/2019] [Indexed: 11/16/2022]
Abstract
The accuracy, reliability, speed and cost of the methods used for malaria diagnosis are key to the diseases' treatment and eventual eradication. However, improvement in any one of these requirements can lead to deterioration of the rest due to their interdependence. We propose an optical method that provides fast detection of malaria-infected red blood cells (RBCs) at a lower cost. The method is based on the combination of deconvolution, topography and three-dimensional (3D) refractive index reconstruction of the malaria-infected RBCs by use of the transport of intensity equation. Using our method, healthy RBCs were identified by their biconcave shape, quasi-uniform spatial distribution of their refractive indices and quasi-uniform concentration of hemoglobin. The values of these optical and biochemical parameters were found to be in agreement with the values reported in the literature. Results for the malaria-infected RBCs were significantly different from those of the healthy RBCs. The topography of the cells and their optical and biochemical parameters enabled identification of their stages of infection. This work introduces a significant method of analyzing malaria-infected RBCs at a lower cost and without the use of fluorescent labels for the parasites.
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Affiliation(s)
- Marcel Akpa Agnero
- Laboratoire de Physique de la Matière Condensée et Technologie, UFR SSMT, Université Félix Houphouët-Boigny, 22 BP 582 Abidjan 22, Côte d'Ivoire.
| | - Kouakou Konan
- Laboratoire d'Instrumentation d'Image et Spectroscopie, Institut National Polytechnique Félix Houphouët-Boigny (INPH-B), BP 1093 Yamoussoukro, Côte d'Ivoire
| | | | - Yao Taky Alvarez Kossonou
- Laboratoire d'Instrumentation d'Image et Spectroscopie, Institut National Polytechnique Félix Houphouët-Boigny (INPH-B), BP 1093 Yamoussoukro, Côte d'Ivoire
| | - Bienvenue Sylvère Dion
- Laboratoire d'Instrumentation d'Image et Spectroscopie, Institut National Polytechnique Félix Houphouët-Boigny (INPH-B), BP 1093 Yamoussoukro, Côte d'Ivoire
| | | | - Jérémie Thouakesséh Zoueu
- Laboratoire d'Instrumentation d'Image et Spectroscopie, Institut National Polytechnique Félix Houphouët-Boigny (INPH-B), BP 1093 Yamoussoukro, Côte d'Ivoire
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31
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Klemm AH, Thomae AW, Wachal K, Dietzel S. Tracking Microscope Performance: A Workflow to Compare Point Spread Function Evaluations Over Time. Microsc Microanal 2019; 25:699-704. [PMID: 30722807 DOI: 10.1017/s1431927619000060] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Routine system checks are essential for supervising the performance of an advanced light microscope. Recording and evaluating the point spread function (PSF) of a given system provides information about the resolution and imaging. We compared the performance of fluorescent and gold beads for PSF recordings. We then combined the open-source evaluation software PSFj with a newly developed KNIME pipeline named PSFtracker to create a standardized workflow to track a system's performance over several measurements and thus over long time periods. PSFtracker produces example images of recorded PSFs, plots full-width-half-maximum (FWHM) measurements over time and creates an html file which embeds the images and plots, together with a table of results. Changes of the PSF over time are thus easily spotted, either in FWHM plots or in the time series of bead images which allows recognition of aberrations in the shape of the PSF. The html file, viewed in a local browser or uploaded on the web, therefore provides intuitive visualization of the state of the PSF over time. In addition, uploading of the html file on the web allows other microscopists to compare such data with their own.
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Affiliation(s)
- Anna H Klemm
- Core Facility Bioimaging at the Biomedical Center and Walter-Brendel-Zentrum für Experimentelle Medizin, Ludwig-Maximilians-Univeristät München,Großhaderner Straße 9, 82152 Planegg-Martinsried,Germany
| | - Andreas W Thomae
- Core Facility Bioimaging at the Biomedical Center and Walter-Brendel-Zentrum für Experimentelle Medizin, Ludwig-Maximilians-Univeristät München,Großhaderner Straße 9, 82152 Planegg-Martinsried,Germany
| | - Katarina Wachal
- Core Facility Bioimaging at the Biomedical Center and Walter-Brendel-Zentrum für Experimentelle Medizin, Ludwig-Maximilians-Univeristät München,Großhaderner Straße 9, 82152 Planegg-Martinsried,Germany
| | - Steffen Dietzel
- Core Facility Bioimaging at the Biomedical Center and Walter-Brendel-Zentrum für Experimentelle Medizin, Ludwig-Maximilians-Univeristät München,Großhaderner Straße 9, 82152 Planegg-Martinsried,Germany
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Zheng Y, Huang W, Pan Y, Xu M. Optimal PSF Estimation for Simple Optical System Using a Wide-Band Sensor Based on PSF Measurement. Sensors (Basel) 2018; 18:s18103552. [PMID: 30347760 PMCID: PMC6210713 DOI: 10.3390/s18103552] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Revised: 09/26/2018] [Accepted: 09/26/2018] [Indexed: 11/17/2022]
Abstract
Simple optical system imaging is a method to simplify optical systems by removing aberrations using image deconvolution. The point spread function (PSF) used in deconvolution is an important factor that affects the image quality. However, it is difficult to obtain optimal PSFs. The blind estimation of PSFs relies heavily on the information in the image. Measured PSFs are often misused because real sensors are wide-band. We present an optimal PSF estimation method based on PSF measurements. Narrow-band PSF measurements at a single depth are used to calibrate the optical system; these enable the simulation of real lenses. Then, we simulate PSFs in the wavelength pass range of each color channel all over the field. The optimal PSFs are computed according to these simulated PSFs. The results indicated that the use of the optimal PSFs significantly reduces the artifacts caused by misuse of PSFs, and enhances the image quality.
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Affiliation(s)
- Yunda Zheng
- State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China.
- University of Chinese Academy of Sciences, Beijing 100049, China.
| | - Wei Huang
- State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China.
| | - Yun Pan
- University of Chinese Academy of Sciences, Beijing 100049, China.
| | - Mingfei Xu
- State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China.
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Dasari PKR, Jones JP, Casey ME, Liang Y, Dilsizian V, Smith MF. The effect of time-of-flight and point spread function modeling on 82Rb myocardial perfusion imaging of obese patients. J Nucl Cardiol 2018; 25:1521-1545. [PMID: 29907933 DOI: 10.1007/s12350-018-1311-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Accepted: 04/13/2018] [Indexed: 11/30/2022]
Abstract
BACKGROUND The effect of time-of-flight (TOF) and point spread function (PSF) modeling in image reconstruction has not been well studied for cardiac PET. This study assesses their separate and combined influence on 82Rb myocardial perfusion imaging in obese patients. METHODS Thirty-six obese patients underwent rest-stress 82Rb cardiac PET. Images were reconstructed with and without TOF and PSF modeling. Perfusion was quantitatively compared using the AHA 17-segment model for patients grouped by BMI, cross-sectional body area in the scanner field of view, gender, and left ventricular myocardial volume. Summed rest scores (SRS), summed stress scores (SSS), and summed difference scores (SDS) were compared. RESULTS TOF improved polar map visual uniformity and increased septal wall perfusion by up to 10%. This increase was greater for larger patients, more evident for patients grouped by cross-sectional area than by BMI, and more prominent for females. PSF modeling increased perfusion by about 1.5% in all cardiac segments. TOF modeling generally decreased SRS and SSS with significant decreases between 2.4 and 3.0 (P < .05), which could affect risk stratification; SDS remained about the same. With PSF modeling, SRS, SSS, and SDS were largely unchanged. CONCLUSION TOF and PSF modeling affect regional and global perfusion, SRS, and SSS. Clinicians should consider these effects and gender-dependent differences when interpreting 82Rb perfusion studies.
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Affiliation(s)
- Paul K R Dasari
- Department of Diagnostic Radiology and Nuclear Medicine, University of Maryland School of Medicine, 22 South Greene St., Baltimore, MD, 21201, USA
| | | | | | - Yuanyuan Liang
- Department of Epidemiology and Public Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Vasken Dilsizian
- Department of Diagnostic Radiology and Nuclear Medicine, University of Maryland School of Medicine, 22 South Greene St., Baltimore, MD, 21201, USA
| | - Mark F Smith
- Department of Diagnostic Radiology and Nuclear Medicine, University of Maryland School of Medicine, 22 South Greene St., Baltimore, MD, 21201, USA.
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Zotta MD, Nevins MC, Hailstone RK, Lifshin E. The Determination and Application of the Point Spread Function in the Scanning Electron Microscope. Microsc Microanal 2018; 24:396-405. [PMID: 30175706 DOI: 10.1017/s1431927618012412] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
A method is presented to determine the spatial distribution of electrons in the focused beam of a scanning electron microscope (SEM). Knowledge of the electron distribution is valuable for characterizing and monitoring SEM performance, as well as for modeling and simulation in computational scanning electron microscopy. Specifically, it can be used to characterize astigmatism as well as study the relationship between beam energy, beam current, working distance, and beam shape and size. In addition, knowledge of the distribution of electrons in the beam can be utilized with deconvolution methods to improve the resolution and quality of backscattered, secondary, and transmitted electron images obtained with thermionic, FEG, or Schottky source instruments. The proposed method represents an improvement over previous methods for determining the spatial distribution of electrons in an SEM beam. Several practical applications are presented.
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Affiliation(s)
- Matthew D Zotta
- 1Nanoscience Constellation of the Colleges of Nanoscience and Engineering,SUNY Polytechnic Institute,Albany,NY 12203,USA
| | - Mandy C Nevins
- 2Center for Imaging Science,Rochester Institute of Technology,Rochester,NY 14623,USA
| | - Richard K Hailstone
- 2Center for Imaging Science,Rochester Institute of Technology,Rochester,NY 14623,USA
| | - Eric Lifshin
- 1Nanoscience Constellation of the Colleges of Nanoscience and Engineering,SUNY Polytechnic Institute,Albany,NY 12203,USA
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35
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Uysal BS, Sarac O, Yaman D, Akcay E, Cagil N. Optical Performance of the Cornea One Year Following Keratoconus Treatment with Corneal Collagen Cross-Linking. Curr Eye Res 2018; 43:1415-1421. [PMID: 30012019 DOI: 10.1080/02713683.2018.1501802] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
PURPOSE The purpose of the study is to assess changes in optical performance of the cornea in patients with keratoconus following treatment with corneal collagen crosslinking (CXL). MATERIALS AND METHODS One hundred and eleven eyes of 111 consecutive keratoconus patients with 12-month follow-up after CXL were included. The changes in the visual acuity, manifest refractive errors, and corneal topographic parameters were evaluated. Sirius dual-scanning corneal tomography was used to determine the effectiveness of CXL on each patient's total corneal optical quality; preoperative and 12-month postoperative measurements were analyzed over a 4-mm stimulated pupil and were compared with regards to higher order corneal aberrations (total amount of higher order aberrations [HOAs], vertical coma, horizontal coma, vertical trefoil, oblique trefoil, and spherical aberration), vertical and horizontal modulation transfer function (MTF), and Strehl ratio of point spread function (PSF). RESULTS At 12 months, there was a significant improvement in mean uncorrected visual acuity (UCVA) (P < 0.001), best corrected visual acuity (BCVA) (P < 0.001), spherical equivalent refraction (P = 0.007), and manifest astigmatic refraction (P < 0.001). The corneal topographic measurements revealed a significant decrease in the mean simulated keratometry-1, simulated keratometry -2, and maximum keratometry compared with the baseline measurements (P < 0.001, for all). In addition, there were significant improvements in mean root mean square error values for corneal total HOA (P < 0.001), vertical coma (P < 0.001), and vertical trefoil (P = 0.008) following CXL. Mean MTF and Strehl ratio did not change after CXL (P > 0.05). The improvement in UCVA significantly correlated with the changes in vertical trefoil (r = -0.191, P = 0.044), and the improvement in BCVA and the changes in manifest astigmatic correction were also significantly correlated (r = -0.247, P = 0.009) 12 months after CXL. CONCLUSIONS CXL treatment for keratoconus led to an improvement in visual, refractive, topographic, and most corneal HOAs outcomes at the 12-month follow-up. However, these improvements were not enough to increase corneal MTF and the Strehl ratio of PSF.
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Affiliation(s)
- Betul Seher Uysal
- a Department of Ophthalmology , Yıldırım Beyazıt University, Atatürk Training and Research Hospital , Ankara , Turkey
| | - Ozge Sarac
- a Department of Ophthalmology , Yıldırım Beyazıt University, Atatürk Training and Research Hospital , Ankara , Turkey
| | - Derya Yaman
- a Department of Ophthalmology , Yıldırım Beyazıt University, Atatürk Training and Research Hospital , Ankara , Turkey
| | - Emine Akcay
- a Department of Ophthalmology , Yıldırım Beyazıt University, Atatürk Training and Research Hospital , Ankara , Turkey
| | - Nurullah Cagil
- a Department of Ophthalmology , Yıldırım Beyazıt University, Atatürk Training and Research Hospital , Ankara , Turkey
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Yang Z, Jin H, Kim JH. Attenuation profile matching: An accurate and scan parameter-robust measurement method for small airway dimensions in low-dose CT scans. Med Phys 2018; 45:4145-4157. [PMID: 29969838 DOI: 10.1002/mp.13074] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Revised: 06/24/2018] [Accepted: 06/24/2018] [Indexed: 12/20/2022] Open
Abstract
PURPOSE The dimensions of small airways with an internal diameter of less than 2-3 mm are important biomarkers for the evaluation of pulmonary diseases, such as asthma and chronic obstructive pulmonary disease (COPD). The resolution limitations of CT systems, however, have remained a barrier to be of use for determining the small airway dimensions. We present a novel approach, called the attenuation profile matching (APM) method, which allows for the accurate determination of the small airway dimension while being robust to varying CT scan parameters. METHOD For generating the synthetic attenuation profiles of an airway, we acquired and employed the point spread functions of a CT system by calculating its convolution with numerical airway models with varying wall thicknesses. The dimensions of a given airway were determined as per the numerical model yielding minimum error between the measured and the synthetic attenuation profiles across the airway. RESULTS In a phantom study with airway tubes, the APM method proved to be highly accurate in determining airway wall dimensions. The measurement error for the smallest tube (0.6 mm thickness, 3 mm diameter) was merely 0.02 mm (3.3%) in wall thickness and 0.17 mm (5.6%) in lumen diameter. In a pilot clinical test, the APM method was able to distinguish the airway wall thicknesses of COPD cases (1.16 ± 0.23 mm) from those of normal subjects (0.6 ± 0.18 mm), while the measurements using the full width at half maximum method substantially overlapped (1.45 ± 0.32 mm vs. 1.28 ± 0.30 mm, respectively) and were barely distinguishable from each other. CONCLUSION Our proposed APM method has the potential to overcome the resolution limitations of current CT systems and accurately determine the small airway dimensions in COPD patients.
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Affiliation(s)
- Zepa Yang
- Program in Biomedical Radiation Sciences, Graduate School of Convergence Science and Technology, Seoul National University, Seoul, 08826, Korea
| | - Hyeongmin Jin
- Program in Biomedical Radiation Sciences, Graduate School of Convergence Science and Technology, Seoul National University, Seoul, 08826, Korea
| | - Jong Hyo Kim
- Program in Biomedical Radiation Sciences, Graduate School of Convergence Science and Technology, Seoul National University, Seoul, 08826, Korea
- Department of Radiology, Seoul National University Hospital, Seoul, 03080, Korea
- Centre for Medical-IT Convergence Technology Research, Advanced Institutes of Convergence Technology, Suwon, 16229, Korea
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Wang Y, Li G, Zhang J, Yi Q, Zhao Y, Li K, Zhu Y, Jiang X. Improving the detection efficiency and modulation transfer function of lens-coupled indirect X-ray imaging detectors based on point spread functions simulated according to lens performance parameters. J Synchrotron Radiat 2018; 25:1093-1105. [PMID: 29979170 DOI: 10.1107/s1600577518007889] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2018] [Accepted: 05/28/2018] [Indexed: 06/08/2023]
Abstract
Lens-coupled indirect X-ray imaging detectors have the advantage of high resolution and the disadvantage of low detection efficiency. Using thicker single-crystalline films (SCFs) can improve the detection efficiency. However, the image quality will become worse due to the degradation of the point spread function (PSF) and modulation transfer function (MTF). This disadvantage can be improved by deconvolution with the PSF, which is unknown. In this article, a method was established to acquire the PSF based on a simulation of the imaging process for a lens-coupled indirect X-ray imaging detector. Because the structural parameters of commercial lenses cannot usually be obtained, the PSFs were calculated from lens performance parameters. PSFs were calculated using the conditions of 12 keV X-ray energy, 10× and 40× magnification objectives and 4.6 µm- and 20 µm-thick GGG:Tb scintillators. These were then used to deconvolve images of an Xradia resolution test pattern taken under the same conditions. The results show that after deconvolution the MTF had been clearly improved for both the 4.6 µm- and 20 µm-thick SCFs, indicating that the image has better quality than before deconvolution. Furthermore, a PSF deconvolution was performed on mouse brain tissue projection images, and the original and deconvolution projection images were used to perform computed-tomography reconstruction; the result proved that the method was effective for improving the image quality of low-contrast samples. Therefore, this method shows promise in allowing the use of thick SCFs to improve the detection efficiency while maintaining good image quality.
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Affiliation(s)
- Yanping Wang
- Institute of High Energy Physics, Chinese Academy of Science, Yuquan Road 19B, Shijingshan District, Beijing 100049, People's Republic of China
| | - Gang Li
- Institute of High Energy Physics, Chinese Academy of Science, Yuquan Road 19B, Shijingshan District, Beijing 100049, People's Republic of China
| | - Jie Zhang
- Institute of High Energy Physics, Chinese Academy of Science, Yuquan Road 19B, Shijingshan District, Beijing 100049, People's Republic of China
| | - Qiru Yi
- University of Chinese Academy of Sciences, Yuquan Road 19A, Shijingshan District, Beijing 100049, People's Republic of China
| | - Yue Zhao
- Institute of High Energy Physics, Chinese Academy of Science, Yuquan Road 19B, Shijingshan District, Beijing 100049, People's Republic of China
| | - Kun Li
- Institute of High Energy Physics, Chinese Academy of Science, Yuquan Road 19B, Shijingshan District, Beijing 100049, People's Republic of China
| | - Ye Zhu
- Institute of High Energy Physics, Chinese Academy of Science, Yuquan Road 19B, Shijingshan District, Beijing 100049, People's Republic of China
| | - Xiaoming Jiang
- Institute of High Energy Physics, Chinese Academy of Science, Yuquan Road 19B, Shijingshan District, Beijing 100049, People's Republic of China
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Vijayan S, Xiong Z, Guo C, Troville J, Islam N, Rudin S, Bednarek DR. Calculation of Forward Scatter Dose Distribution at the skin entrance from the patient table for fluoroscopically guided interventions using a pencil beam convolution kernel. Proc SPIE Int Soc Opt Eng 2018; 10573. [PMID: 29904230 DOI: 10.1117/12.2294920] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
The forward-scatter dose distribution generated by the patient table during fluoroscopic interventions and its contribution to the skin dose is studied. The forward-scatter dose distribution to skin generated by a water table-equivalent phantom and the patient table are calculated using EGSnrc Monte-Carlo and Gafchromic film as a function of x-ray field size and beam penetrability. Forward scatter point spread function's (PSFn) were generated with EGSnrc from a 1×1 mm simulated primary pencil beam incident on the water model and patient table. The forward-scatter point spread function normalized to the primary is convolved over the primary-dose distribution to generate scatter-dose distributions. The utility of PSFn to calculate the entrance skin dose distribution using DTS (dose tracking system) software is investigated. The forward-scatter distribution calculations were performed for 2.32 mm, 3.10 mm, 3.84 mm and 4.24 mm Al HVL x-ray beams for 5×5 cm, 9×9 cm, 13.5×13.5 cm sized x-ray fields for water and 3.1 mm Al HVL x-ray beam for 16.5×16.5 cm field for the patient table. The skin dose is determined with DTS by convolution of the scatter dose PSFn's and with Gafchromic film under PMMA "patient-simulating" blocks for uniform and for shaped x-ray fields. The normalized forward-scatter distribution determined using the convolution method for water table-equivalent phantom agreed with that calculated for the full field using EGSnrc within ±6%. The normalized forward-scatter dose distribution calculated for the patient table for a 16.5×16.5 cm FOV, agreed with that determined using film within ±2.4%. For the homogenous PMMA phantom, the skin dose using DTS was calculated within ±2 % of that measured with the film for both uniform and non-uniform x-ray fields. The convolution method provides improved accuracy over using a single forward-scatter value over the entire field and is a faster alternative to performing full-field Monte-Carlo calculations.
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Affiliation(s)
- Sarath Vijayan
- Canon Stroke and Vascular Research Center, University at Buffalo, Buffalo, NY, USA
| | - Zhenyu Xiong
- Canon Stroke and Vascular Research Center, University at Buffalo, Buffalo, NY, USA
| | - Chao Guo
- Canon Stroke and Vascular Research Center, University at Buffalo, Buffalo, NY, USA
| | - Jonathan Troville
- Canon Stroke and Vascular Research Center, University at Buffalo, Buffalo, NY, USA
| | - Naveed Islam
- Canon Stroke and Vascular Research Center, University at Buffalo, Buffalo, NY, USA
| | - Stephen Rudin
- Canon Stroke and Vascular Research Center, University at Buffalo, Buffalo, NY, USA.,Department of Radiology, University at Buffalo, Buffalo, NY, USA
| | - Daniel R Bednarek
- Canon Stroke and Vascular Research Center, University at Buffalo, Buffalo, NY, USA.,Department of Radiology, University at Buffalo, Buffalo, NY, USA
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Rajendran K, Leng S, Jorgensen SM, Anderson JL, Halaweish AF, Abdurakhimova D, Ritman EL, McCollough CH. Measuring arterial wall perfusion using photon-counting computed tomography (CT): improving CT number accuracy of artery wall using image deconvolution. J Med Imaging (Bellingham) 2017; 4:044006. [PMID: 29250564 DOI: 10.1117/1.jmi.4.4.044006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Accepted: 10/20/2017] [Indexed: 11/14/2022] Open
Abstract
Changes in arterial wall perfusion mark the onset of atherosclerosis. A characteristic change is the increased spatial density of vasa vasorum (VV), the microvessels in the arterial walls. Measuring this increased VV (IVV) density using contrast-enhanced computed tomography (CT) has had limited success due to blooming effects from contrast media. If the system point-spread function (PSF) is known, then the blooming effect can be modeled as a convolution between the true signal and the PSF. We report the application of image deconvolution to improve the CT number accuracy in the arterial wall of a phantom and in a porcine model of IVV density, both scanned using a whole-body research photon-counting CT scanner. A 3D-printed carotid phantom filled with three concentrations of iodinated contrast material was scanned to assess blooming and its effect on wall CT number accuracy. The results showed a reduction in blooming effects following image deconvolution, and, consequently, a better delineation between lumen and wall was achieved. Results from the animal experiment showed improved CT number difference between the carotid with IVV density and the normal carotid artery after deconvolution, enabling the detection of VV proliferation, which may serve as an early indicator of atherosclerosis.
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Affiliation(s)
- Kishore Rajendran
- Mayo Clinic, Department of Radiology, Rochester, Minnesota, United States
| | - Shuai Leng
- Mayo Clinic, Department of Radiology, Rochester, Minnesota, United States
| | - Steven M Jorgensen
- Mayo Clinic, Department of Physiology and Biomedical Engineering, Rochester, Minnesota, United States
| | - Jill L Anderson
- Mayo Clinic, Department of Physiology and Biomedical Engineering, Rochester, Minnesota, United States
| | | | | | - Erik L Ritman
- Mayo Clinic, Department of Physiology and Biomedical Engineering, Rochester, Minnesota, United States
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Matheoud R, Lecchi M, Lizio D, Scabbio C, Marcassa C, Leva L, Del Sole A, Rodella C, Indovina L, Bracco C, Brambilla M, Zoccarato O. Comparative analysis of iterative reconstruction algorithms with resolution recovery and time of flight modeling for 18F-FDG cardiac PET: A multi-center phantom study. J Nucl Cardiol 2017; 24:1036-1045. [PMID: 26758376 DOI: 10.1007/s12350-015-0385-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Accepted: 08/21/2015] [Indexed: 10/22/2022]
Abstract
BACKGROUND The purpose of this study was to evaluate the image quality in cardiac 18F-FDG PET using the time of flight (TOF) and/or point spread function (PSF) modeling in the iterative reconstruction (IR). METHODS Three scanners and an anthropomorphic cardiac phantom with an insert simulating a transmural defect (TD) were used. Two sets of scans (with/without TD) were acquired, and four reconstruction schemes were considered: (1) IR; (2) IR + PSF, (3) IR + TOF, and (4) IR + TOF + PSF. LV wall thickness (FWHM), contrast between LV wall and inner chamber (C IC), and TD contrast in LV wall (C TD) were evaluated. RESULTS Tests of the reconstruction protocols showed a decrease in FWHM from IR (13 mm) to IR + PSF (11 mm); an increase in the C IC from IR (65%) to IR + PSF (71%) and from IR + TOF (72%) to IR + TOF + PSF (77%); and an increase in the C TD from IR + PSF (72%) to IR + TOF (75%) and to IR + TOF + PSF (77%). Tests of the scanner/software combinations showed a decrease in FWHM from Gemini_TF (13 mm) to Biograph_mCT (12 mm) and to Discovery_690 (11 mm); an increase in the C IC from Gemini_TF (65%) to Biograph_mCT (73%) and to Discovery_690 (75%); and an increase in the C TD from Gemini_TF/Biograph_mCT (72%) to Discovery_690 (77%). CONCLUSION The introduction of TOF and PSF increases image quality in cardiac 18F-FDG PET. The scanner/software combinations exhibit different performances, which should be taken into consideration when making cross comparisons.
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Affiliation(s)
- Roberta Matheoud
- Departments of Medical Physics and Nuclear Medicine, University Hospital, Novara, Italy
| | - Michela Lecchi
- Department of Health Sciences, University of Milan and Nuclear Medicine Unit, San Paolo Hospital, Milan, Italy
| | - Domenico Lizio
- Departments of Medical Physics and Nuclear Medicine, University Hospital, Novara, Italy
| | - Camilla Scabbio
- Department of Health Sciences, University of Milan and Nuclear Medicine Unit, San Paolo Hospital, Milan, Italy
| | - Claudio Marcassa
- Unit of Nuclear Medicine and Department of Cardiology, S. Maugeri Foundation, IRCCS, Veruno, Italy
| | - Lucia Leva
- Departments of Medical Physics and Nuclear Medicine, University Hospital, Novara, Italy
| | - Angelo Del Sole
- Department of Health Sciences, University of Milan and Nuclear Medicine Unit, San Paolo Hospital, Milan, Italy
| | - Carlo Rodella
- Health Physics Unit, Spedali Civili Hospital, Brescia, Italy
| | - Luca Indovina
- Department of Medical Physics, Polyclinic Agostino Gemelli, Rome, Italy
| | - Christian Bracco
- Medical Physics Department, Institute for Cancer Research and Treatment, Candiolo, Italy
| | - Marco Brambilla
- Departments of Medical Physics and Nuclear Medicine, University Hospital, Novara, Italy.
| | - Orazio Zoccarato
- Department of Health Sciences, University of Milan and Nuclear Medicine Unit, San Paolo Hospital, Milan, Italy
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Shi Z, Wu R, Yang PF, Wang F, Wu TL, Mishra A, Chen LM, Gore JC. High spatial correspondence at a columnar level between activation and resting state fMRI signals and local field potentials. Proc Natl Acad Sci U S A 2017; 114:5253-8. [PMID: 28461461 DOI: 10.1073/pnas.1620520114] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Although blood oxygenation level-dependent (BOLD) fMRI has been widely used to map brain responses to external stimuli and to delineate functional circuits at rest, the extent to which BOLD signals correlate spatially with underlying neuronal activity, the spatial relationships between stimulus-evoked BOLD activations and local correlations of BOLD signals in a resting state, and whether these spatial relationships vary across functionally distinct cortical areas are not known. To address these critical questions, we directly compared the spatial extents of stimulated activations and the local profiles of intervoxel resting state correlations for both high-resolution BOLD at 9.4 T and local field potentials (LFPs), using 98-channel microelectrode arrays, in functionally distinct primary somatosensory areas 3b and 1 in nonhuman primates. Anatomic images of LFP and BOLD were coregistered within 0.10 mm accuracy. We found that the point spread functions (PSFs) of BOLD and LFP responses were comparable in the stimulus condition, and both estimates of activations were slightly more spatially constrained than local correlations at rest. The magnitudes of stimulus responses in area 3b were stronger than those in area 1 and extended in a medial to lateral direction. In addition, the reproducibility and stability of stimulus-evoked activation locations within and across both modalities were robust. Our work suggests that the intrinsic resolution of BOLD is not a limiting feature in practice and approaches the intrinsic precision achievable by multielectrode electrophysiology.
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Park NS, Chun SK, Han GH, Kim CS. Acousto-Optic-Based Wavelength-Comb-Swept Laser for Extended Displacement Measurements. Sensors (Basel) 2017; 17:E740. [PMID: 28362318 DOI: 10.3390/s17040740] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Revised: 03/27/2017] [Accepted: 03/28/2017] [Indexed: 11/17/2022]
Abstract
We demonstrate a novel wavelength-comb-swept laser based on two intra-cavity filters: an acousto-optic tunable filter (AOTF) and a Fabry-Pérot etalon filter. The AOTF is used for the tunable selection of the output wavelength with time and the etalon filter for the narrowing of the spectral linewidth to extend the coherence length. Compared to the conventional wavelength-swept laser, the acousto-optic–based wavelength-comb-swept laser (WCSL) can extend the measureable range of displacement measurements by decreasing the sensitivity roll-off of the point spread function. Because the AOTF contains no mechanical moving parts to select the output wavelength acousto-optically, the WCSL source has a high wavenumber (k) linearity of R2 = 0.9999 to ensure equally spaced wavelength combs in the wavenumber domain.
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Xiong Z, Vijayan S, Rudin S, Bednarek DR. Monte Carlo investigation of backscatter point spread function for X-ray imaging examinations. Proc SPIE Int Soc Opt Eng 2017; 10132:1013243. [PMID: 28615791 PMCID: PMC5467737 DOI: 10.1117/12.2254064] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
X-ray imaging examinations, especially complex interventions, may result in relatively high doses to the patient's skin inducing skin injuries. A method was developed to determine the skin-dose distribution for non-uniform x-ray beams by convolving the backscatter point-spread-function (PSF) with the primary-dose distribution to generate the backscatter distribution that, when added to the primary dose, gives the total-dose distribution. This technique was incorporated in the dose-tracking system (DTS), which provides a real-time color-coded 3D-mapping of skin dose during fluoroscopic procedures. The aim of this work is to investigate the variation of the backscatter PSF with different parameters. A backscatter PSF of a 1-mm x-ray beam was generated by EGSnrc Monte-Carlo code for different x-ray beam energies, different soft-tissue thickness above bone, different bone thickness and different entrance-beam angles, as well as for different locations on the SK-150 anthropomorphic head phantom. The results show a reduction of the peak scatter to primary dose ratio of 48% when X-ray beam voltage is increased from 40 keV to 120 keV. The backscatter dose was reduced when bone was beneath the soft tissue layer and this reduction increased with thinner soft tissue and thicker bone layers. The backscatter factor increased about 21% as the angle of incidence of the beam with the entrance surface decreased from 90° (perpendicular) to 30°. The backscatter PSF differed for different locations on the SK-150 phantom by up to 15%. The results of this study can be used to improve the accuracy of dose calculation when using PSF convolution in the DTS.
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Affiliation(s)
- Zhenyu Xiong
- University at Buffalo, Department of Physiology and Biophysics, 124 Sherman Hall, 3435 Main Street, Buffalo, New York 14214, United States
- Toshiba Stroke & Vascular Research Center, 875 Ellicott Street, Buffalo, New York 14203, United States
| | - Sarath Vijayan
- University at Buffalo, Department of Physiology and Biophysics, 124 Sherman Hall, 3435 Main Street, Buffalo, New York 14214, United States
- Toshiba Stroke & Vascular Research Center, 875 Ellicott Street, Buffalo, New York 14203, United States
| | - Stephen Rudin
- University at Buffalo, Department of Physiology and Biophysics, 124 Sherman Hall, 3435 Main Street, Buffalo, New York 14214, United States
- University at Buffalo, Department of Radiology, 319A Sherman Hall, 3435 Main Street, Buffalo, New York 14214, United States
- Toshiba Stroke & Vascular Research Center, 875 Ellicott Street, Buffalo, New York 14203, United States
| | - Daniel R Bednarek
- University at Buffalo, Department of Physiology and Biophysics, 124 Sherman Hall, 3435 Main Street, Buffalo, New York 14214, United States
- University at Buffalo, Department of Radiology, 319A Sherman Hall, 3435 Main Street, Buffalo, New York 14214, United States
- Toshiba Stroke & Vascular Research Center, 875 Ellicott Street, Buffalo, New York 14203, United States
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Vijayan S, Xiong Z, Shankar A, Rudin S, Bednarek DR. Skin dose mapping for non-uniform x-ray fields using a backscatter point spread function. Proc SPIE Int Soc Opt Eng 2017; 10132:101320U. [PMID: 28649154 PMCID: PMC5478926 DOI: 10.1117/12.2254257] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Beam shaping devices like ROI attenuators and compensation filters modulate the intensity distribution of the x-ray beam incident on the patient. This results in a spatial variation of skin dose due to the variation of primary radiation and also a variation in backscattered radiation from the patient. To determine the backscatter component, backscatter point spread functions (PSF) are generated using EGS Monte-Carlo software. For this study, PSF's were determined by simulating a 1 mm beam incident on the lateral surface of an anthropomorphic head phantom and a 20 cm thick PMMA block phantom. The backscatter PSF's for the head phantom and PMMA phantom are curve fit with a Lorentzian function after being normalized to the primary dose intensity (PSFn). PSFn is convolved with the primary dose distribution to generate the scatter dose distribution, which is added to the primary to obtain the total dose distribution. The backscatter convolution technique is incorporated in the dose tracking system (DTS), which tracks skin dose during fluoroscopic procedures and provides a color map of the dose distribution on a 3D patient graphic model. A convolution technique is developed for the backscatter dose determination for the non-uniformly spaced graphic-model surface vertices. A Gafchromic film validation was performed for shaped x-ray beams generated with an ROI attenuator and with two compensation filters inserted into the field. The total dose distribution calculated by the backscatter convolution technique closely agreed with that measured with the film.
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Affiliation(s)
- Sarath Vijayan
- Toshiba Stroke and Vascular Research Center, University at Buffalo, Buffalo, NY, USA
- Department of Physiology and Biophysics, University at Buffalo, Buffalo, NY, USA
| | - Zhenyu Xiong
- Toshiba Stroke and Vascular Research Center, University at Buffalo, Buffalo, NY, USA
- Department of Physiology and Biophysics, University at Buffalo, Buffalo, NY, USA
| | - Alok Shankar
- Toshiba Stroke and Vascular Research Center, University at Buffalo, Buffalo, NY, USA
- Department of Physiology and Biophysics, University at Buffalo, Buffalo, NY, USA
| | - Stephen Rudin
- Toshiba Stroke and Vascular Research Center, University at Buffalo, Buffalo, NY, USA
- Department of Physiology and Biophysics, University at Buffalo, Buffalo, NY, USA
- Department of Radiology, University at Buffalo, Buffalo, NY, USA
| | - Daniel R Bednarek
- Toshiba Stroke and Vascular Research Center, University at Buffalo, Buffalo, NY, USA
- Department of Physiology and Biophysics, University at Buffalo, Buffalo, NY, USA
- Department of Radiology, University at Buffalo, Buffalo, NY, USA
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Zhang Y, Shi T, Su L, Wang X, Hong Y, Chen K, Liao G. Sparse Reconstruction for Micro Defect Detection in Acoustic Micro Imaging. Sensors (Basel) 2016; 16:E1773. [PMID: 27783040 DOI: 10.3390/s16101773] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Revised: 09/30/2016] [Accepted: 10/12/2016] [Indexed: 11/16/2022]
Abstract
Acoustic micro imaging has been proven to be sufficiently sensitive for micro defect detection. In this study, we propose a sparse reconstruction method for acoustic micro imaging. A finite element model with a micro defect is developed to emulate the physical scanning. Then we obtain the point spread function, a blur kernel for sparse reconstruction. We reconstruct deblurred images from the oversampled C-scan images based on l₁-norm regularization, which can enhance the signal-to-noise ratio and improve the accuracy of micro defect detection. The method is further verified by experimental data. The results demonstrate that the sparse reconstruction is effective for micro defect detection in acoustic micro imaging.
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Gajda J, Stencel M. Eddy-Current Sensors with Asymmetrical Point Spread Function. Sensors (Basel) 2016; 16:E1642. [PMID: 27782033 DOI: 10.3390/s16101642] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Accepted: 09/15/2016] [Indexed: 11/17/2022]
Abstract
This paper concerns a special type of eddy-current sensor in the form of inductive loops. Such sensors are applied in the measuring systems classifying road vehicles. They usually have a rectangular shape with dimensions of 1 × 2 m, and are installed under the surface of the traffic lane. The wide Point Spread Function (PSF) of such sensors causes the information on chassis geometry, contained in the measurement signal, to be strongly averaged. This significantly limits the effectiveness of the vehicle classification. Restoration of the chassis shape, by solving the inverse problem (deconvolution), is also difficult due to the fact that it is ill-conditioned. An original approach to solving this problem is presented in this paper. It is a hardware-based solution and involves the use of inductive loops with an asymmetrical PSF. Laboratory experiments and simulation tests, conducted with models of an inductive loop, confirmed the effectiveness of the proposed solution. In this case, the principle applies that the higher the level of sensor spatial asymmetry, the greater the effectiveness of the deconvolution algorithm.
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Yang H, Trouillon R, Huszka G, Gijs MAM. Super-Resolution Imaging of a Dielectric Microsphere Is Governed by the Waist of Its Photonic Nanojet. Nano Lett 2016; 16:4862-70. [PMID: 27398718 DOI: 10.1021/acs.nanolett.6b01255] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Dielectric microspheres with appropriate refractive index can image objects with super-resolution, that is, with a precision well beyond the classical diffraction limit. A microsphere is also known to generate upon illumination a photonic nanojet, which is a scattered beam of light with a high-intensity main lobe and very narrow waist. Here, we report a systematic study of the imaging of water-immersed nanostructures by barium titanate glass microspheres of different size. A numerical study of the light propagation through a microsphere points out the light focusing capability of microspheres of different size and the waist of their photonic nanojet. The former correlates to the magnification factor of the virtual images obtained from linear test nanostructures, the biggest magnification being obtained with microspheres of ∼6-7 μm in size. Analyzing the light intensity distribution of microscopy images allows determining analytically the point spread function of the optical system and thereby quantifies its resolution. We find that the super-resolution imaging of a microsphere is dependent on the waist of its photonic nanojet, the best resolution being obtained with a 6 μm Ø microsphere, which generates the nanojet with the minimum waist. This comparison allows elucidating the super-resolution imaging mechanism.
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Affiliation(s)
- Hui Yang
- Laboratory of Microsystems, École Polytechnique Fédérale de Lausanne , 1015 Lausanne, Switzerland
| | - Raphaël Trouillon
- Laboratory of Microsystems, École Polytechnique Fédérale de Lausanne , 1015 Lausanne, Switzerland
| | - Gergely Huszka
- Laboratory of Microsystems, École Polytechnique Fédérale de Lausanne , 1015 Lausanne, Switzerland
| | - Martin A M Gijs
- Laboratory of Microsystems, École Polytechnique Fédérale de Lausanne , 1015 Lausanne, Switzerland
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Chao J, Ram S, Ward ES, Ober RJ. Investigating the usage of point spread functions in point source and microsphere localization. Proc SPIE Int Soc Opt Eng 2016; 9713:97131M. [PMID: 27141148 PMCID: PMC4851249 DOI: 10.1117/12.2208631] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Using a point spread function (PSF) to localize a point-like object, such as a fluorescent molecule or microsphere, represents a common task in single molecule microscopy image data analysis. The localization may differ in purpose depending on the application or experiment, but a unifying theme is the importance of being able to closely recover the true location of the point-like object with high accuracy. We present two simulation studies, both relating to the performance of object localization via the maximum likelihood fitting of a PSF to the object's image. In the first study, we investigate the integration of the PSF over an image pixel, which represents a critical part of the localization algorithm. Specifically, we explore how the fineness of the integration affects how well a point source can be localized, and find the use of too coarse a step size to produce location estimates that are far from the true location, especially when the images are acquired at relatively low magnifications. We also propose a method for selecting an appropriate step size. In the second study, we investigate the suitability of the common practice of using a PSF to localize a microsphere, despite the mismatch between the microsphere's image and the fitted PSF. Using criteria based on the standard errors of the mean and variance, we find the method suitable for microspheres up to 1 μm and 100 nm in diameter, when the localization is performed, respectively, with and without the simultaneous estimation of the width of the PSF.
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Affiliation(s)
- Jerry Chao
- Dept. of Biomedical Engineering, Texas A&M University, College Station, TX 77843, USA; Dept. of Molecular and Cellular Medicine, Texas A&M Health Science Center, College Station, TX 77843, USA
| | - Sripad Ram
- Dept. of Electrical Engineering, University of Texas at Dallas, Richardson, TX 75080, USA
| | - E Sally Ward
- Dept. of Molecular and Cellular Medicine, Texas A&M Health Science Center, College Station, TX 77843, USA; Dept. of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, College Station, TX 77843, USA
| | - Raimund J Ober
- Dept. of Biomedical Engineering, Texas A&M University, College Station, TX 77843, USA; Dept. of Molecular and Cellular Medicine, Texas A&M Health Science Center, College Station, TX 77843, USA
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Abstract
Axial excitation confinement beyond the diffraction limit is crucial to the development of next-generation, super-resolution microscopy. STimulated Emission Depletion (STED) nanoscopy offers lateral super-resolution using a donut-beam depletion, but its axial resolution is still over 500 nm. Total internal reflection fluorescence microscopy is widely used for single-molecule localization, but its ability to detect molecules is limited to within the evanescent field of ~ 100 nm from the cell attachment surface. We find here that the axial thickness of the point spread function (PSF) during confocal excitation can be easily improved to 110 nm by replacing the microscopy slide with a mirror. The interference of the local electromagnetic field confined the confocal PSF to a 110-nm spot axially, which enables axial super-resolution with all laser-scanning microscopes. Axial sectioning can be obtained with wavelength modulation or by controlling the spacer between the mirror and the specimen. With no additional complexity, the mirror-assisted excitation confinement enhanced the axial resolution six-fold and the lateral resolution two-fold for STED, which together achieved 19-nm resolution to resolve the inner rim of a nuclear pore complex and to discriminate the contents of 120 nm viral filaments. The ability to increase the lateral resolution and decrease the thickness of an axial section using mirror-enhanced STED without increasing the laser power is of great importance for imaging biological specimens, which cannot tolerate high laser power.
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Affiliation(s)
- Xusan Yang
- Department of Biomedical Engineering, College of Engineering, Peking University, No. 5 Yiheyuan Road, Beijing 100871, China
| | - Hao Xie
- Department of Biomedical Engineering, College of Engineering, Peking University, No. 5 Yiheyuan Road, Beijing 100871, China
- Wallace H Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA 30332, USA
| | - Eric Alonas
- Wallace H Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA 30332, USA
| | - Yujia Liu
- Department of Biomedical Engineering, College of Engineering, Peking University, No. 5 Yiheyuan Road, Beijing 100871, China
- Advanced Cytometry Labs, ARC Centre of Excellence for Nanoscale BioPhotonics (CNBP), Macquarie University, Sydney, NSW 2109, Australia
| | - Xuanze Chen
- Department of Biomedical Engineering, College of Engineering, Peking University, No. 5 Yiheyuan Road, Beijing 100871, China
| | - Philip J Santangelo
- Wallace H Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA 30332, USA
| | - Qiushi Ren
- Department of Biomedical Engineering, College of Engineering, Peking University, No. 5 Yiheyuan Road, Beijing 100871, China
| | - Peng Xi
- Department of Biomedical Engineering, College of Engineering, Peking University, No. 5 Yiheyuan Road, Beijing 100871, China
- Wallace H Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA 30332, USA
- Advanced Cytometry Labs, ARC Centre of Excellence for Nanoscale BioPhotonics (CNBP), Macquarie University, Sydney, NSW 2109, Australia
- Institute for Biomedical Materials and Devices (IBMD), Faculty of Science, University of Technology Sydney, Sydney, NSW 2007, Australia
| | - Dayong Jin
- Advanced Cytometry Labs, ARC Centre of Excellence for Nanoscale BioPhotonics (CNBP), Macquarie University, Sydney, NSW 2109, Australia
- Institute for Biomedical Materials and Devices (IBMD), Faculty of Science, University of Technology Sydney, Sydney, NSW 2007, Australia
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Doganay O, Wade T, Hegarty E, McKenzie C, Schulte RF, Santyr GE. Hyperpolarized (129) Xe imaging of the rat lung using spiral IDEAL. Magn Reson Med 2015; 76:566-76. [PMID: 26332385 DOI: 10.1002/mrm.25911] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Revised: 08/03/2015] [Accepted: 08/06/2015] [Indexed: 12/22/2022]
Abstract
PURPOSE To implement and optimize a single-shot spiral encoding strategy for rapid 2D IDEAL projection imaging of hyperpolarized (Hp) (129) Xe in the gas phase, and in the pulmonary tissue (PT) and red blood cells (RBCs) compartments of the rat lung, respectively. THEORY AND METHODS A theoretical and experimental point spread function analysis was used to optimize the spiral k-space read-out time in a phantom. Hp (129) Xe IDEAL images from five healthy rats were used to: (i) optimize flip angles by a Bloch equation analysis using measured kinetics of gas exchange and (ii) investigate the feasibility of the approach to characterize the exchange of Hp (129) Xe. RESULTS A read-out time equal to approximately 1.8 × T2* was found to provide the best trade-off between spatial resolution and signal-to-noise ratio (SNR). Spiral IDEAL approaches that use the entire dissolved phase magnetization should give an SNR improvement of a factor of approximately three compared with Cartesian approaches with similar spatial resolution. The IDEAL strategy allowed imaging of gas, PT, and RBC compartments with sufficient SNR and temporal resolution to permit regional gas exchange measurements in healthy rats. CONCLUSION Single-shot spiral IDEAL imaging of gas, PT and RBC compartments and gas exchange is feasible in rat lung using Hp (129) Xe. Magn Reson Med 76:566-576, 2016. © 2015 Wiley Periodicals, Inc.
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Affiliation(s)
- Ozkan Doganay
- Department of Medical Biophysics, Western University, London, ON, Canada.,Imaging Research Laboratories, Robarts Research Institute, London, ON, Canada
| | - Trevor Wade
- Department of Medical Biophysics, Western University, London, ON, Canada.,Imaging Research Laboratories, Robarts Research Institute, London, ON, Canada
| | - Elaine Hegarty
- Imaging Research Laboratories, Robarts Research Institute, London, ON, Canada
| | - Charles McKenzie
- Department of Medical Biophysics, Western University, London, ON, Canada.,Imaging Research Laboratories, Robarts Research Institute, London, ON, Canada.,Department of Medical Imaging, Western University, London, ON, Canada
| | | | - Giles E Santyr
- Department of Medical Biophysics, Western University, London, ON, Canada.,Imaging Research Laboratories, Robarts Research Institute, London, ON, Canada.,Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children, Toronto, ON, Canada.,Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada
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