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Bahar P, Nguyen D, Wang M, Mazilu D, Bennett EE, Wen H. Online Calibration of a Linear Micro Tomosynthesis Scanner. J Imaging 2022; 8:jimaging8100292. [PMID: 36286386 PMCID: PMC9604648 DOI: 10.3390/jimaging8100292] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Revised: 10/11/2022] [Accepted: 10/14/2022] [Indexed: 11/16/2022] Open
Abstract
In a linear tomosynthesis scanner designed for imaging histologic samples of several centimeters size at 10 µm resolution, the mechanical instability of the scanning stage (±10 µm) exceeded the resolution of the image system, making it necessary to determine the trajectory of the stage for each scan to avoid blurring and artifacts in the images that would arise from the errors in the geometric information used in 3D reconstruction. We present a method for online calibration by attaching a layer of randomly dispersed micro glass beads or calcium particles to the bottom of the sample stage. The method was based on a parametric representation of the rigid body motion of the sample stage-marker layer assembly. The marker layer was easy to produce and proven effective in the calibration procedure.
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Nguyen DT, Larsen TC, Wang M, Knutsen RH, Yang Z, Bennett EE, Mazilu D, Yu ZX, Tao X, Donahue DR, Gharib AM, Bleck CKE, Moss J, Remaley AT, Kozel BA, Wen H. X-ray microtomosynthesis of unstained pathology tissue samples. J Microsc 2021; 283:9-20. [PMID: 33482682 PMCID: PMC8248055 DOI: 10.1111/jmi.13003] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [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: 08/13/2020] [Revised: 12/14/2020] [Accepted: 01/17/2021] [Indexed: 12/15/2022]
Abstract
In pathology protocols, a tissue block, such as one containing a mouse brain or a biopsy sample from a patient, can produce several hundred thin sections. Substantial time may be required to analyse all sections. In cases of uncertainty regarding which sections to focus on, noninvasive scout imaging of intact blocks can help in guiding the pathology procedure. The scouting step is ideally done in a time window of minutes without special sample preparation that may interfere with the pathology procedures. The challenge is to obtain some visibility of unstained tissue structures at sub‐10 µm resolution. We explored a novel x‐ray tomosynthesis method as a way to maximise contrast‐to‐noise ratio, a determinant of tissue visibility. It provided a z‐stack of thousands of images at 7.3 μm resolution (10% contrast, half‐period of 68.5 line pairs/mm), in scans of 5‐15 minutes. When compared with micro‐CT scans, the straight‐line tomosynthesis scan did not need to rotate the sample, which allowed flat samples, such as paraffin blocks, to be kept as close as possible to the x‐ray source. Thus, given the same hardware, scan time and resolution, this mode maximised the photon flux density through the sample, which helped in maximising the contrast‐to‐noise ratio. The tradeoff of tomosynthesis is incomplete 3D information. The microtomosynthesis scanner has scanned 110 unstained human and animal tissue samples as part of their respective pathology protocols. In all cases, the z‐stack of images showed tissue structures that guided sectioning or provided correlative structural information. We describe six examples that presented different levels of visibility of soft tissue structures. Additionally, in a set of coronary artery samples from an HIV patient donor, microtomosynthesis made a new discovery of isolated focal calcification in the internal elastic lamina of coronary wall, which was the onset of medial calcific sclerosis in the arteries.
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Affiliation(s)
- David T Nguyen
- National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland
| | | | - Muyang Wang
- National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland
| | - Russel H Knutsen
- National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland
| | - Zhihong Yang
- National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland
| | - Eric E Bennett
- National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland
| | - Dumitru Mazilu
- National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland
| | - Zu-Xi Yu
- National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland
| | - Xi Tao
- School of Biomedical Engineering, Southern Medical University, Guangzhou, Guangdong, China
| | - Danielle R Donahue
- Mouse Imaging Facility, National Institutes of Health, Bethesda, Maryland
| | - Ahmed M Gharib
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland
| | - Christopher K E Bleck
- National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland
| | - Joel Moss
- National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland
| | - Alan T Remaley
- National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland
| | - Beth A Kozel
- National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland
| | - Han Wen
- National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland
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Larsen TC, Bennett EE, Mazilu D, Chen MY, Wen H. Regional Ultrahigh-Resolution Rescan in a Clinical Whole-Body CT Scanner Using a Contact Detector Insert. ACTA ACUST UNITED AC 2019; 5:233-238. [PMID: 31245544 PMCID: PMC6588199 DOI: 10.18383/j.tom.2019.00002] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Ultrahigh-resolution, low-dose rescans in a region of interest following a general screening computed tomography (CT) scan is motivated by the need to reduce invasive tissue biopsy procedures in cancer screening. We describe a new method to meet the conflicting demands of ultrahigh resolution, high-speed and ultralow-dose, and the first proof-of-concept experiment. With improving detector resolution, the limiting factor for the system resolution of whole-body CT scanners shifts to the penumbra of the source focal spot. The penumbra unsharpness is minimized by inserting flat-panel detector(s) that are in direct contact with the body. In the hybrid system, the detector insert and the CT detector acquire data simultaneously, whereby the standard CT images give the position and orientation of the detector insert(s) as needed for tomosynthesis reconstruction. Imaging tests were performed with a compact photon-counting detector insert on resolution targets of both high- and low-contrast as well as a mouse specimen, all inside a body phantom. Detector insert tomosynthesis provided twice the resolution of the CT scanner alone at the same dose concentration. The short 2-cm beam collimation of the tomosynthesis rescan gave an effective dose equivalent to 6% of an average CT scan in the chest or abdomen.
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Affiliation(s)
- Thomas C Larsen
- Imaging Physics Laboratory, Biochemistry and Biophysics Center and
| | - Eric E Bennett
- Imaging Physics Laboratory, Biochemistry and Biophysics Center and
| | - Dumitru Mazilu
- Imaging Physics Laboratory, Biochemistry and Biophysics Center and
| | - Marcus Y Chen
- Cardiovascular Branch, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MA
| | - Han Wen
- Imaging Physics Laboratory, Biochemistry and Biophysics Center and
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Mirzaeimoghri M, Morales Martinez A, Panna A, Bennett EE, Lucotte BM, DeVoe DL, Wen H. Nano-printed miniature compound refractive lens for desktop hard x-ray microscopy. PLoS One 2018; 13:e0203319. [PMID: 30161240 PMCID: PMC6117077 DOI: 10.1371/journal.pone.0203319] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Accepted: 08/17/2018] [Indexed: 11/30/2022] Open
Abstract
Hard x-ray lenses are useful elements in x-ray microscopy and in creating focused illumination for analytical applications such as x-ray fluorescence imaging. Recently, polymer compound refractive lenses for focused illumination in the soft x-ray regime (< 10 keV) have been created with nano-printing. However, there are no such lenses yet for hard x-rays, particularly of short focal lengths for benchtop microscopy. We report the first instance of a nano-printed lens for hard x-ray microscopy, and evaluate its imaging performance. The lens consists of a spherically focusing compound refractive lens designed for 22 keV photon energy, with a tightly packed structure to provide a short total length of 1.8 mm and a focal length of 21.5 mm. The resulting lens technology was found to enable benchtop microscopy at 74x magnification and 1.1 μm de-magnified image pixel size at the object plane. It was used to image and evaluate the focal spots of tungsten-anode micro-focus x-ray sources. The overall system resolution with broadband illumination from a tungsten-anode x-ray tube at 30 kV and 10 mm focal distance was measured to be 2.30±0.22 μm.
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Affiliation(s)
- Mona Mirzaeimoghri
- Imaging Physics Laboratory, Biochemistry and Biophysics Center, National Heart, Lung and Blood Institute, National Institute of Health, Bethesda, Maryland, United States of America
- Department of Mechanical Engineering, University of Maryland, College Park, Maryland, United States of America
| | - Alejandro Morales Martinez
- Imaging Physics Laboratory, Biochemistry and Biophysics Center, National Heart, Lung and Blood Institute, National Institute of Health, Bethesda, Maryland, United States of America
| | - Alireza Panna
- Imaging Physics Laboratory, Biochemistry and Biophysics Center, National Heart, Lung and Blood Institute, National Institute of Health, Bethesda, Maryland, United States of America
| | - Eric E. Bennett
- Imaging Physics Laboratory, Biochemistry and Biophysics Center, National Heart, Lung and Blood Institute, National Institute of Health, Bethesda, Maryland, United States of America
| | - Bertrand M. Lucotte
- Cardiac Energetic Laboratory, National Heart, Lung and Blood Institute, National Institute of Health, Bethesda, Maryland, United States of America
| | - Don L. DeVoe
- Department of Mechanical Engineering, University of Maryland, College Park, Maryland, United States of America
| | - Han Wen
- Imaging Physics Laboratory, Biochemistry and Biophysics Center, National Heart, Lung and Blood Institute, National Institute of Health, Bethesda, Maryland, United States of America
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5
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George A, Chen PY, Morales-Martinez A, Panna A, Gomella AA, Bennett EE, Wen H. Geometric calibration and correction for a lens-coupled detector in x-ray phase-contrast imaging. J Med Imaging (Bellingham) 2017; 4:013507. [PMID: 28382313 DOI: 10.1117/1.jmi.4.1.013507] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [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: 08/23/2016] [Accepted: 03/02/2017] [Indexed: 11/14/2022] Open
Abstract
A lens-coupled x-ray camera with a tilted phosphor collects light emission from the x-ray illuminated (front) side of phosphor. Experimentally, it has been shown to double x-ray photon capture efficiency and triple the spatial resolution along the phosphor tilt direction relative to the same detector at normal phosphor incidence. These characteristics benefit grating-based phase-contrast methods, where linear interference fringes need to be clearly resolved. However, both the shallow incident angle on the phosphor and lens aberrations of the camera cause geometric distortions. When tiling multiple images of limited vertical view into a full-field image, geometric distortion causes blurring due to image misregistration. Here, we report a procedure of geometric correction based on global polynomial transformation of image coordinates. The corrected image is equivalent to one obtained with a single full-field flat panel detector placed at the sample plane. In a separate evaluation scan, the position deviations in the horizontal and vertical directions were reduced from 0.76 and 0.028 mm, respectively, to 0.006 and 0.009 mm, respectively, by the correction procedure, which were below the 0.028-mm pixel size of the imaging system. In a demonstration of a phase-contrast imaging experiment, the correction reduced blurring of small structures.
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Affiliation(s)
- Alex George
- National Institutes of Health , National Heart, Lung and Blood Institute, Biochemistry and Biophysics Center, Imaging Physics Laboratory, Bethesda, Maryland, United States
| | - Peter Y Chen
- National Institutes of Health , National Heart, Lung and Blood Institute, Biochemistry and Biophysics Center, Imaging Physics Laboratory, Bethesda, Maryland, United States
| | - Alejandro Morales-Martinez
- National Institutes of Health , National Heart, Lung and Blood Institute, Biochemistry and Biophysics Center, Imaging Physics Laboratory, Bethesda, Maryland, United States
| | - Alireza Panna
- National Institutes of Health , National Heart, Lung and Blood Institute, Biochemistry and Biophysics Center, Imaging Physics Laboratory, Bethesda, Maryland, United States
| | - Andrew A Gomella
- National Institutes of Health , National Heart, Lung and Blood Institute, Biochemistry and Biophysics Center, Imaging Physics Laboratory, Bethesda, Maryland, United States
| | - Eric E Bennett
- National Institutes of Health , National Heart, Lung and Blood Institute, Biochemistry and Biophysics Center, Imaging Physics Laboratory, Bethesda, Maryland, United States
| | - Han Wen
- National Institutes of Health , National Heart, Lung and Blood Institute, Biochemistry and Biophysics Center, Imaging Physics Laboratory, Bethesda, Maryland, United States
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Miao H, Panna A, Gomella AA, Bennett EE, Znati S, Chen L, Wen H. A Universal Moiré Effect and Application in X-Ray Phase-Contrast Imaging. Nat Phys 2016; 12:830-834. [PMID: 27746823 PMCID: PMC5063246 DOI: 10.1038/nphys3734] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
A moiré pattern is created by superimposing two black-and-white or gray-scale patterns of regular geometry, such as two sets of evenly spaced lines. We observed an analogous effect between two transparent phase masks in a light beam which occurs at a distance. This phase moiré effect and the classic moiré effect are shown to be the two ends of a continuous spectrum. The phase moiré effect allows the detection of sub-resolution intensity or phase patterns with a transparent screen. When applied to x-ray imaging, it enables a polychromatic far-field interferometer (PFI) without absorption gratings. X-ray interferometry can non-invasively detect refractive index variations inside an object1-10. Current bench-top interferometers operate in the near field with limitations in sensitivity and x-ray dose efficiency2, 5, 7-10. The universal moiré effect helps overcome these limitations and obviates the need to make hard x-ray absorption gratings of sub-micron periods.
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Affiliation(s)
- Houxun Miao
- Biophysics and Biochemistry Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Alireza Panna
- Biophysics and Biochemistry Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Andrew A Gomella
- Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Eric E Bennett
- Biophysics and Biochemistry Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Sami Znati
- Biophysics and Biochemistry Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Lei Chen
- Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, Maryland, USA
| | - Han Wen
- Biophysics and Biochemistry Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA
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Znati SA, Chedid N, Miao H, Chen L, Bennett EE, Wen H. Electrodeposition of Gold to Conformally Fill High Aspect Ratio Nanometric Silicon Grating Trenches: A Comparison of Pulsed and Direct Current Protocols. J Surf Eng Mater Adv Technol 2015; 5:207-213. [PMID: 27042384 PMCID: PMC4812826 DOI: 10.4236/jsemat.2015.54022] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Filling high-aspect-ratio trenches with gold is a frequent requirement in the fabrication of x-ray optics as well as micro-electronic components and other fabrication processes. Conformal electrodeposition of gold in sub-micron-width silicon trenches with an aspect ratio greater than 35 over a grating area of several square centimeters is challenging and has not been described in the literature previously. A comparison of pulsed plating and constant current plating led to a gold electroplating protocol that reliably filled trenches for such structures.
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Affiliation(s)
- Sami A. Znati
- Imaging Physics Laboratory, Biochemistry and Biophysics Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Nicholas Chedid
- Imaging Physics Laboratory, Biochemistry and Biophysics Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Houxun Miao
- Imaging Physics Laboratory, Biochemistry and Biophysics Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Lei Chen
- Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, MD 20899
| | - Eric E. Bennett
- Imaging Physics Laboratory, Biochemistry and Biophysics Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Han Wen
- Imaging Physics Laboratory, Biochemistry and Biophysics Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892
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8
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Miao H, Gomella AA, Harmon KJ, Bennett EE, Chedid N, Znati S, Panna A, Foster BA, Bhandarkar P, Wen H. Enhancing Tabletop X-Ray Phase Contrast Imaging with Nano-Fabrication. Sci Rep 2015; 5:13581. [PMID: 26315891 PMCID: PMC4551996 DOI: 10.1038/srep13581] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Accepted: 07/30/2015] [Indexed: 11/09/2022] Open
Abstract
X-ray phase-contrast imaging is a promising approach for improving soft-tissue contrast and lowering radiation dose in biomedical applications. While current tabletop imaging systems adapt to common x-ray tubes and large-area detectors by employing absorptive elements such as absorption gratings or monolithic crystals to filter the beam, we developed nanometric phase gratings which enable tabletop x-ray far-field interferometry with only phase-shifting elements, leading to a substantial enhancement in the performance of phase contrast imaging. In a general sense the method transfers the demands on the spatial coherence of the x-ray source and the detector resolution to the feature size of x-ray phase masks. We demonstrate its capabilities in hard x-ray imaging experiments at a fraction of clinical dose levels and present comparisons with the existing Talbot-Lau interferometer and with conventional digital radiography.
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Affiliation(s)
- Houxun Miao
- Imaging Physics Laboratory, Biochemistry and Biophysics Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Andrew A Gomella
- Imaging Physics Laboratory, Biochemistry and Biophysics Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Katherine J Harmon
- Imaging Physics Laboratory, Biochemistry and Biophysics Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Eric E Bennett
- Imaging Physics Laboratory, Biochemistry and Biophysics Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Nicholas Chedid
- Imaging Physics Laboratory, Biochemistry and Biophysics Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Sami Znati
- Imaging Physics Laboratory, Biochemistry and Biophysics Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Alireza Panna
- Imaging Physics Laboratory, Biochemistry and Biophysics Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Barbara A Foster
- Breast Imaging Center, Walter Reed National Military Medical Center, Bethesda, MD 20889
| | - Priya Bhandarkar
- Breast Imaging Center, Walter Reed National Military Medical Center, Bethesda, MD 20889
| | - Han Wen
- Imaging Physics Laboratory, Biochemistry and Biophysics Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892
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Harmon KJ, Miao H, Gomella AA, Bennett EE, Foster BA, Bhandarkar P, Wen H. Motionless electromagnetic phase stepping versus mechanical phase stepping in x-ray phase-contrast imaging with a compact source. Phys Med Biol 2015; 60:3031-43. [PMID: 25803511 DOI: 10.1088/0031-9155/60/8/3031] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
X-ray phase contrast imaging based on grating interferometers detects the refractive index distribution of an object without relying on radiation attenuation, thereby having the potential for reduced radiation absorption. These techniques belong to the broader category of optical wavefront measurement, which requires stepping the phase of the interference pattern to obtain a pixel-wise map of the phase distortion of the wavefront. While phase stepping traditionally involves mechanical scanning of a grating or mirror, we developed electromagnetic phase stepping (EPS) for imaging with compact sources to obviate the need for mechanical movement. In EPS a solenoid coil is placed outside the x-ray tube to shift its focal spot with a magnetic field, causing a relative movement between the projection of the sample and the interference pattern in the image. Here we present two embodiments of this method. We verified experimentally that electromagnetic and mechanical phase stepping give the same results and attain the same signal-to-noise ratios under the same radiation dose. We found that the relative changes of interference fringe visibility were within 3.0% when the x-ray focal spot was shifted by up to 1.0 mm in either direction. We conclude that when using x-ray tube sources, EPS is an effective means of phase stepping without the need for mechanical movement.
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Affiliation(s)
- Katherine J Harmon
- Imaging Physics Laboratory, Biochemistry and Biophysics Center, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
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10
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Lynch SK, Liu C, Morgan NY, Xiao X, Gomella AA, Mazilu D, Bennett EE, Assoufid L, de Carlo F, Wen H. Fabrication of 200 nanometer period centimeter area hard x-ray absorption gratings by multilayer deposition. J Micromech Microeng 2012; 22:105007. [PMID: 23066175 PMCID: PMC3468157 DOI: 10.1088/0960-1317/22/10/105007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
We describe the design and fabrication trials of x-ray absorption gratings of 200 nm period and up to 100:1 depth-to-period ratios for full-field hard x-ray imaging applications. Hard x-ray phase-contrast imaging relies on gratings of ultra-small periods and sufficient depth to achieve high sensitivity. Current grating designs utilize lithographic processes to produce periodic vertical structures, where grating periods below 2.0 μm are difficult due to the extreme aspect ratios of the structures. In our design, multiple bilayers of x-ray transparent and opaque materials are deposited on a staircase substrate, and mostly on the floor surfaces of the steps only. When illuminated by an x-ray beam horizontally, the multilayer stack on each step functions as a micro-grating whose grating period is the thickness of a bilayer. The array of micro-gratings over the length of the staircase works as a single grating over a large area when continuity conditions are met. Since the layers can be nanometers thick and many microns wide, this design allows sub-micron grating periods and sufficient grating depth to modulate hard x-rays. We present the details of the fabrication process and diffraction profiles and contact radiography images showing successful intensity modulation of a 25 keV x-ray beam.
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Affiliation(s)
- S K Lynch
- Imaging Physics Lab, Biochemistry and Biophysics Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - C Liu
- X-Ray Science Division, Advanced Photon Source, Argonne National Laboratory Argonne, IL 60439, USA
| | - N Y Morgan
- National Institute of Biomedical Imaging and Bioengineering, NIH, Bethesda, MD, 20892, USA
| | - X Xiao
- X-Ray Science Division, Advanced Photon Source, Argonne National Laboratory Argonne, IL 60439, USA
| | - A A Gomella
- Imaging Physics Lab, Biochemistry and Biophysics Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - D Mazilu
- Imaging Physics Lab, Biochemistry and Biophysics Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - E E Bennett
- Imaging Physics Lab, Biochemistry and Biophysics Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - L Assoufid
- X-Ray Science Division, Advanced Photon Source, Argonne National Laboratory Argonne, IL 60439, USA
| | - F de Carlo
- X-Ray Science Division, Advanced Photon Source, Argonne National Laboratory Argonne, IL 60439, USA
| | - H Wen
- Imaging Physics Lab, Biochemistry and Biophysics Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, 20892, USA
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Wen H, Kemble CK, Bennett EE. Theory of oblique and grazing incidence Talbot‑Lau interferometers and demonstration in a compact source x‑ray reflective interferometer. Opt Express 2011; 19:25093-112. [PMID: 22273901 PMCID: PMC3407979 DOI: 10.1364/oe.19.025093] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2011] [Revised: 11/11/2011] [Accepted: 11/12/2011] [Indexed: 05/20/2023]
Abstract
With the advent of Talbot-Lau interferometers for x-ray phase-contrast imaging, oblique and grazing incidence configurations are now used in the pursuit of sub-micron grating periods and high sensitivity. Here we address the question whether interferometers having oblique incident beams behave in the same way as the well-understood normal incidence ones, particularly when the grating planes are non-parallel. We derive the normal incidence equivalence of oblique incidence geometries from wave propagation modeling. Based on the theory, we propose a practical method to correct for non-parallelism of the grating planes, and demonstrate its effectiveness with a polychromatic hard x-ray reflective interferometer.
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Affiliation(s)
- Han Wen
- National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA.
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12
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Lynch SK, Pai V, Auxier J, Stein AF, Bennett EE, Kemble CK, Xiao X, Lee WK, Morgan NY, Wen HH. Interpretation of dark-field contrast and particle-size selectivity in grating interferometers. Appl Opt 2011; 50:4310-9. [PMID: 21833104 PMCID: PMC3407965 DOI: 10.1364/ao.50.004310] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
In grating-based x-ray phase sensitive imaging, dark-field contrast refers to the extinction of the interference fringes due to small-angle scattering. For configurations where the sample is placed before the beamsplitter grating, the dark-field contrast has been quantified with theoretical wave propagation models. Yet when the grating is placed before the sample, the dark-field contrast has only been modeled in the geometric optics regime. Here we attempt to quantify the dark-field effect in the grating-before-sample geometry with first-principle wave calculations and understand the associated particle-size selectivity. We obtain an expression for the dark-field effect in terms of the sample material's complex refractive index, which can be verified experimentally without fitting parameters. A dark-field computed tomography experiment shows that the particle-size selectivity can be used to differentiate materials of identical x-ray absorption.
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Affiliation(s)
- Susanna K. Lynch
- Lab of Imaging Physics, Translational Medicine Branch, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Vinay Pai
- Lab of Imaging Physics, Translational Medicine Branch, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Julie Auxier
- School of Chemical, Biological and Environmental Engineering, Oregon State University, Corvallis, Oregon 97331, USA
| | | | - Eric E. Bennett
- Lab of Imaging Physics, Translational Medicine Branch, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Camille K. Kemble
- Lab of Imaging Physics, Translational Medicine Branch, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Xianghui Xiao
- X-Ray Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - Wah-Keat Lee
- X-Ray Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - Nicole Y. Morgan
- Lab of Imaging Physics, Translational Medicine Branch, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Han Harold Wen
- Lab of Imaging Physics, Translational Medicine Branch, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
- Corresponding author:
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Bennett EE, Kopace R, Stein AF, Wen H. A grating-based single-shot x-ray phase contrast and diffraction method for in vivo imaging. Med Phys 2011; 37:6047-54. [PMID: 21158316 DOI: 10.1118/1.3501311] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE The purpose of this study is to develop a single-shot version of the grating-based phase contrast x-ray imaging method and demonstrate its capability of in vivo animal imaging. Here, the authors describe the principle and experimental results. They show the source of artifacts in the phase contrast signal and optimal designs that minimize them. They also discuss its current limitations and ways to overcome them. METHODS A single lead grid was inserted midway between an x-ray tube and an x-ray camera in the planar radiography setting. The grid acted as a transmission grating and cast periodic dark fringes on the camera. The camera had sufficient spatial resolution to resolve the fringes. Refraction and diffraction in the imaged object manifested as position shifts and amplitude attenuation of the fringes, respectively. In order to quantify these changes precisely without imposing a fixed geometric relationship between the camera pixel array and the fringes, a spatial harmonic method in the Fourier domain was developed. The level of the differential phase (refraction) contrast as a function of hardware specifications and device geometry was derived and used to guide the optimal placement of the grid and object. Both ex vivo and in vivo images of rodent extremities were collected to demonstrate the capability of the method. The exposure time using a 50 W tube was 28 s. RESULTS Differential phase contrast images of glass beads acquired at various grid and object positions confirmed theoretical predictions of how phase contrast and extraneous artifacts vary with the device geometry. In anesthetized rats, a single exposure yielded artifact-free images of absorption, differential phase contrast, and diffraction. Differential phase contrast was strongest at bone-soft tissue interfaces, while diffraction was strongest in bone. CONCLUSIONS The spatial harmonic method allowed us to obtain absorption, differential phase contrast, and diffraction images, all from a single raw image and is feasible in live animals. Because the sensitivity of the method scales with the density of the gratings, custom microfabricated gratings should be superior to off-the-shelf lead grids.
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Affiliation(s)
- Eric E Bennett
- National Heart, Lung, and Blood Institute, National Institutes of Health, Imaging Physics Section, Translational Medicine Branch, 10 Center Drive, MSC 1061, Bethesda, Maryland 20892, USA.
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Kemble CK, Auxier J, Lynch SK, Bennett EE, Morgan NY, Wen H. Grazing angle Mach-Zehnder interferometer using reflective phase gratings and a polychromatic, un-collimated light source. Opt Express 2010; 18:27481-92. [PMID: 21197023 PMCID: PMC3088511 DOI: 10.1364/oe.18.027481] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Normal incidence Talbot-Lau interferometers in x-ray applications have the drawbacks of low fringe visibility with polychromatic sources when the wave propagation distance is increased to achieve higher phase sensitivity, and when fabrication limits the attainable grating density. In contrast, reflective gratings illuminated at grazing angles have dramatically higher effective densities than their physical values. However, new designs are needed for far field interferometers using grazing angle geometry with incoherent light sources. We show that, with the appropriate design and choice of reflective phase gratings, there exist pairs of interfering pathways of exactly equal lengths independent of the incoming beam's incidence angle and wavelength. With a visible light grazing angle Mach-Zehnder interferometer, we show the conditions for achieving near ideal fringe visibility and demonstrate both absolute and differential phase-contrast imaging. We also describe the design parameters of an x-ray interferometer and key factors for its implementation.
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Affiliation(s)
- Camille K. Kemble
- Imaging Physics Section, National Heart, Lung and Blood Institute, Bethesda, MD, 20892, USA
| | - Julie Auxier
- Intramural Research Programs,National Institute of Biomedical Imaging and Bioengineering National Institutes of Health, Bethesda, MD, 20892, USA
| | - Susanna K. Lynch
- Imaging Physics Section, National Heart, Lung and Blood Institute, Bethesda, MD, 20892, USA
| | - Eric E. Bennett
- Imaging Physics Section, National Heart, Lung and Blood Institute, Bethesda, MD, 20892, USA
| | - Nicole Y. Morgan
- Intramural Research Programs,National Institute of Biomedical Imaging and Bioengineering National Institutes of Health, Bethesda, MD, 20892, USA
| | - Han Wen
- Imaging Physics Section, National Heart, Lung and Blood Institute, Bethesda, MD, 20892, USA
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Le Y, Stein A, Berry C, Kellman P, Bennett EE, Taylor J, Lucas K, Kopace R, Chefd’Hotel C, Lorenz CH, Croisille P, Wen H. Simultaneous myocardial strain and dark-blood perfusion imaging using a displacement-encoded MRI pulse sequence. Magn Reson Med 2010; 64:787-98. [PMID: 20544714 PMCID: PMC2932773 DOI: 10.1002/mrm.22461] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2009] [Accepted: 03/01/2010] [Indexed: 11/06/2022]
Abstract
The purpose of this study is to develop and evaluate a displacement-encoded pulse sequence for simultaneous perfusion and strain imaging. Displacement-encoded images in two to three myocardial slices were repeatedly acquired using a single-shot pulse sequence for 3 to 4 min, which covers a bolus infusion of Gadolinium contrast. The magnitudes of the images were T(1) weighted and provided quantitative measures of perfusion, while the phase maps yielded strain measurements. In an acute coronary occlusion swine protocol (n = 9), segmental perfusion measurements were validated against microsphere reference standard with a linear regression (slope 0.986, R(2) = 0.765, Bland-Altman standard deviation = 0.15 mL/min/g). In a group of ST-elevation myocardial infarction patients (n = 11), the scan success rate was 76%. Short-term contrast washout rate and perfusion are highly correlated (R(2) = 0.72), and the pixelwise relationship between circumferential strain and perfusion was better described with a sigmoidal Hill curve than linear functions. This study demonstrates the feasibility of measuring strain and perfusion from a single set of images.
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Affiliation(s)
- Yuan Le
- National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Ashley Stein
- National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Colin Berry
- Western Infirmary & Associated Hospital, Dept. Cardiology, Glasgow, Scotland
| | - Peter Kellman
- National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Eric E. Bennett
- National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Joni Taylor
- National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Katherine Lucas
- National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Rael Kopace
- National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | | | | | - Pierre Croisille
- Departement de Radiologie, Hôpital Cardiologique et Pneumologique, L. Pradel, Lyon, France
| | - Han Wen
- National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, USA
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Wen HH, Bennett EE, Kopace R, Stein AF, Pai V. Single-shot x-ray differential phase-contrast and diffraction imaging using two-dimensional transmission gratings. Opt Lett 2010; 35:1932-4. [PMID: 20548343 PMCID: PMC3091831 DOI: 10.1364/ol.35.001932] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
We describe an x-ray differential phase-contrast imaging method based on two-dimensional transmission gratings that are directly resolved by an x-ray camera. X-ray refraction and diffraction in the sample lead to variations of the positions and amplitudes of the grating fringes on the camera. These effects can be quantified through spatial harmonic analysis. The use of 2D gratings allows differential phase contrast in several directions to be obtained from a single image. When compared to previous grating-based interferometry methods, this approach obviates the need for multiple exposures and separate measurements for different directions and thereby accelerates imaging speed.
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Affiliation(s)
- Harold H Wen
- Imaging Physics Section, Translational Medicine Branch, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892, USA.
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Stein AF, Ilavsky J, Kopace R, Bennett EE, Wen H. Selective imaging of nano-particle contrast agents by a single-shot x-ray diffraction technique. Opt Express 2010; 18:13271-8. [PMID: 20588456 PMCID: PMC3100656 DOI: 10.1364/oe.18.013271] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Iron oxide nano-particles have very different x-ray diffraction properties from tissue. They can be clearly visualized against suppressed tissue background in a single-shot x-ray diffraction imaging technique. This technique is able to acquire both diffraction and absorption images from a single grating-modulated projection image through analysis in the spatial frequency domain. We describe the use of two orthogonal transmission gratings to selectively retain diffraction signal from iron oxide particles that are larger than a threshold size, while eliminating the background signal from soft tissue and bone. This approach should help the tracking of functionalized particles in cell labeling and targeted therapy.
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Affiliation(s)
- Ashley F. Stein
- Imaging Physic Section, Translational Medicine Branch, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Jan Ilavsky
- X-Ray Science Division, Advanced Photon Source, Argonne National Laboratory Argonne, IL 60439, USA
| | - Rael Kopace
- Imaging Physic Section, Translational Medicine Branch, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Eric E. Bennett
- Imaging Physic Section, Translational Medicine Branch, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Han Wen
- Imaging Physic Section, Translational Medicine Branch, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, 20892, USA
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Abstract
PURPOSE To characterize certain aspects of the microscopic structures of cortical and trabecular bone by using Fourier x-ray scattering imaging. MATERIALS AND METHODS Protocols approved by the National Institutes of Health Animal Care and Use Committee were used to examine ex vivo the hind limb of a rat and the toe of a pig. The Fourier x-ray scattering imaging technique involves the use of a grid mask to modulate the cone beam and Fourier spectral filters to isolate the harmonic images. The technique yields attenuation, scattering, and phase-contrast (PC) images from a single exposure. In the rat tibia cortical bone, the scattering signals from two orthogonal grid orientations were compared by using Wilcoxon signed rank tests. In the pig toe, the heterogeneity of scattering and PC signals was compared between trabecular and compact bone regions of uniform attenuation by using F tests. RESULTS In cortical bone, the scattering signal was significantly higher (P < 10(-15)) when the grid was parallel to the periosteal surface. Trabecular bone, as compared with cortical bone, appeared highly heterogeneous on the scattering (P < 10(-34)) and PC (P < 10(-27)) images. CONCLUSION The ordered alignment of the mineralized collagen fibrils in compact bone was reflected in the anisotropic scattering signal in this bone. In trabecular bone, the porosity of the mineralized matrix accounted for the granular pattern seen on the scattering and PC images.
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Affiliation(s)
- Han Wen
- National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA.
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Le Y, Kellman P, Bennett EE, Lin A, Chefd'Hotel C, Lorenz CH, Wen H. 1082 Free-breathing single-shot DENSE myocardial strain imaging using deformable registration. J Cardiovasc Magn Reson 2008. [DOI: 10.1186/1532-429x-10-s1-a207] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Abstract
Coherent X-ray scattering is related to the electron density distribution by a Fourier transform, and therefore a window into the microscopic structures of biological samples. Current techniques of scattering rely on small-angle measurements from highly collimated X-ray beams produced from synchrotron light sources. Imaging of the distribution of scattering provides a new contrast mechanism which is different from absorption radiography, but is a lengthy process of raster or line scans of the beam over the object. Here, we describe an imaging technique in the spatial frequency domain capable of acquiring both the scattering and absorption distributions in a single exposure. We present first results obtained with conventional X-ray equipment. This method interposes a grid between the X-ray source and the imaged object, so that the grid-modulated image contains a primary image and a grid harmonic image. The ratio between the harmonic and primary images is shown to be a pure scattering image. It is the auto-correlation of the electron density distribution at a specific distance. We tested a number of samples at 60-200 nm autocorrelation distance, and found the scattering images to be distinct from the absorption images and reveal new features. This technique is simple to implement, and should help broaden the imaging applications of X-ray scattering.
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Affiliation(s)
- Han Wen
- Laboratory of Cardiac Energetics, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA.
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Wen H, Marsolo KA, Bennett EE, Kutten KS, Lewis RP, Lipps DB, Epstein ND, Plehn JF, Croisille P. Adaptive postprocessing techniques for myocardial tissue tracking with displacement-encoded MR imaging. Radiology 2008; 246:229-40. [PMID: 18096537 DOI: 10.1148/radiol.2461070053] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
UNLABELLED The purpose of this study was to prospectively assess the effects of two adaptive postprocessing techniques on the evaluation of myocardial function with displacement-encoded magnetic resonance (MR) imaging, including sensitivity for abnormal wall motion, with two-dimensional echocardiography as the reference standard. Sixteen patients (11 men, five women; age range, 26-74 years) and 12 volunteers (six men, six women; age range, 29-53 years) underwent breath-hold MR imaging. Institutional review board approval and informed consent were obtained. Adaptive phase-unwrapping and spatial filtering techniques were compared with conventional phase-unwrapping and spatial filtering techniques. Use of the adaptive techniques led to a reduced rate of failure with the phase-unwrapping technique from 18.9% to 0.6% (P < .001), resulted in lower variability of segmental strain measurements among healthy volunteers (P < .001 to P = .02), and increased the sensitivity of quantitative detection of abnormal segments in patients from 82.5% to 87.7% (P = .034). The adaptive techniques improved the semiautomated postprocessing of displacement-encoded cardiac images and increased the sensitivity of detection of abnormal wall motion in patients. SUPPLEMENTAL MATERIAL http://radiology.rsnajnls.org/cgi/content/full/246/1/229/DC1.
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Affiliation(s)
- Han Wen
- National Heart, Lung and Blood Institute, National Institutes of Health, Bldg 10, B1D416, 10 Center Dr, Bethesda, MD 20892, USA.
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Gubash SM, Bennett EE. Use of terpene-based solvents (Hemo-De, Histoclear, and Shandon and BDH xylene substitutes) in place of xylene in the Ehrlich indole test. J Clin Microbiol 1989; 27:2136-7. [PMID: 2778079 PMCID: PMC267760 DOI: 10.1128/jcm.27.9.2136-2137.1989] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Although less effective than xylene and Kovacs reagent as indole extractants, Hemo-De and Shandon xylene substitute can be used in the Ehrlich indole test if a less toxic solvent is desirable. In doubtful cases, xylene should be used. Because of the blocking action shown in the test, use of indole-nitrite broth cannot be recommended.
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Affiliation(s)
- S M Gubash
- Provincial Laboratory of Public Health for Southern Alberta, Calgary, Canada
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Bennett EE. Experiments with Mallein. J Comp Med Vet Arch 1892; 13:53-57. [PMID: 36390788 PMCID: PMC9310869] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
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