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Deng L, Ahmed MF, Jayarathna S, Feng P, Wei B, Cho SH. A detector's eye view (DEV)-based OSEM algorithm for benchtop x-ray fluorescence computed tomography (XFCT) image reconstruction. Phys Med Biol 2019; 64:08NT02. [PMID: 30958796 DOI: 10.1088/1361-6560/ab0e9d] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
In this study, we developed a detector's eye view (DEV)-based ordered subsets expectation maximization (OSEM) algorithm for more accurate reconstruction of benchtop x-ray fluorescence computed tomography (XFCT) images. The proposed approach was tested using two sets of benchtop XFCT imaging data derived from a newly performed gold nanoparticle (GNP)-containing phantom imaging study and a previously published postmortem benchtop XFCT imaging study of a tumor-bearing mouse injected with GNPs. DEV-based OSEM resulted in higher spatial resolution (up to ~20% decrease in the full width at half maximum values of the regions of interest), compared with filtered back-projection (FBP) and traditional OSEM. It also resulted in up to an order of magnitude smaller background noise in the reconstructed images than FBP, while producing consistently less background noise than traditional OSEM.
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Affiliation(s)
- Luzhen Deng
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, United States of America. Key Laboratory of Optoelectronics Technology and System, Chongqing University, Ministry of Education, Chongqing 400044, People's Republic of China
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Chen M, Wang D, Cai N, Xia D, Zou J, Yu H. FBP-type CT reconstruction algorithms for triple-source circular trajectory with different scanning radii. JOURNAL OF X-RAY SCIENCE AND TECHNOLOGY 2019; 27:665-684. [PMID: 31256110 DOI: 10.3233/xst-190494] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Multi-source computed tomography (CT) imaging has unique technical advantages not only for dynamic objects, but also for large-size objects by designing its imaging scan mode. Using the triple-source fan-beam imaging scan mode under three circular trajectories with two different radii, we in this study developed and analyzed theoretically several exact reconstruction algorithms in terms of full-scan and short-scan for three sets of truncated projection data. This triple-source scan configuration in different radii cases is easier to be simulated by a single-source scan configuration in an industrial CT system. The proposed algorithms are based on the idea of filtering-back-projection (FBP) algorithm, and can reconstruct the large-size objects under the same CT devices. The developed algorithms avoid data rebinning and can provide exact and fast image reconstruction. The results of the numerical simulation based data analysis verified that new algorithms were accurate and effective.
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Affiliation(s)
- Ming Chen
- College of Mathematics and Systems Science, Shandong University of Science and Technology, Qingdao, People's Republic of China
| | - Dan Wang
- College of Mathematics and Systems Science, Shandong University of Science and Technology, Qingdao, People's Republic of China
| | - Ning Cai
- College of Mathematics and Systems Science, Shandong University of Science and Technology, Qingdao, People's Republic of China
| | - Dimeng Xia
- College of Mathematics and Systems Science, Shandong University of Science and Technology, Qingdao, People's Republic of China
| | - Jing Zou
- State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University, Tianjin, People's Republic of China
| | - Hengyong Yu
- Department of Electrical and Computer Engineering, University of Massachusetts Lowell, Lowell, Massachusetts, USA
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Deng L, Wei B, He P, Zhang Y, Feng P. A Geant4-based Monte Carlo study of a benchtop multi-pinhole X-ray fluorescence computed tomography imaging. Int J Nanomedicine 2018; 13:7207-7216. [PMID: 30510413 PMCID: PMC6231504 DOI: 10.2147/ijn.s179875] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Background X-ray fluorescence (XRF) computed tomography (XFCT) has shown promise for molecular imaging of metal nanoparticles such as gold nanoparticles (GNPs) and benchtop XFCT is under active development due to its easy access, low-cost instrumentation and operation. Purpose To validate the performance of a Geant4-based Monte Carlo (MC) model of a benchtop multi-pinhole XFCT system for quantitative imaging of GNPs. Methods The MC mode consisted of a fan-beam x-ray source (125 kVp), which was used to stimulate the emission of XRF from the GNPs, a phantom (3 cm in diameter) which included six or nine inserts (3 mm in diameter), each of which contained the same (1 wt. %) or various (0.08–1 wt. %) concentrations of GNPs, a multi-pinhole collimator which could acquire multiple projections simultaneously and a one-sided or two-sided two-dimensional (2D) detector. Various pinhole diameters (3.7, 2, 1, 0.5 and 0.25 mm) and various particle numbers (20, 40, 80 and 100 billion) were simulated and the results for single pinhole and multi-pinhole (9 pinholes) imaging were compared. Results The image resolution for a 1 mm multi-pinhole was between 0.88 and 1.38 mm. The detection limit for multi-pinhole operation was about 0.09 wt. %, while that for the single pinhole was about 0.13 wt. %. For a fixed number of pinholes, noise increased with decreasing number of photons. Conclusion The MC mode could acquire 2D slice images of the object without rotation and demonstrated that a multi-pinhole XFCT imaging system could be a potential bioimaging modality for nanomedical applications.
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Affiliation(s)
- Luzhen Deng
- Key Laboratory of Optoelectronics Technology and System, Chongqing University, Ministry of Education, Chongqing 400044, China, .,Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Biao Wei
- Key Laboratory of Optoelectronics Technology and System, Chongqing University, Ministry of Education, Chongqing 400044, China,
| | - Peng He
- Key Laboratory of Optoelectronics Technology and System, Chongqing University, Ministry of Education, Chongqing 400044, China, .,Engineering Research Center of Industrial Computed Tomography Nondestructive Testing, Chongqing University, Ministry of Education, Chongqing 400044, Chinal,
| | - Yi Zhang
- College of Computer Science, Sichuan University, Chengdu 610065, China
| | - Peng Feng
- Key Laboratory of Optoelectronics Technology and System, Chongqing University, Ministry of Education, Chongqing 400044, China, .,Engineering Research Center of Industrial Computed Tomography Nondestructive Testing, Chongqing University, Ministry of Education, Chongqing 400044, Chinal,
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Mulligan KR, Ferland CE, Gawri R, Borthakur A, Haglund L, Ouellet JA. Axial T1ρ MRI as a diagnostic imaging modality to quantify proteoglycan concentration in degenerative disc disease. EUROPEAN SPINE JOURNAL : OFFICIAL PUBLICATION OF THE EUROPEAN SPINE SOCIETY, THE EUROPEAN SPINAL DEFORMITY SOCIETY, AND THE EUROPEAN SECTION OF THE CERVICAL SPINE RESEARCH SOCIETY 2014; 24:2395-401. [PMID: 25236594 DOI: 10.1007/s00586-014-3582-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Revised: 09/09/2014] [Accepted: 09/09/2014] [Indexed: 12/14/2022]
Abstract
PURPOSE The aim of the study was to investigate if axial T1ρ MR images had similar accuracy as established sagittal T1ρ MRI for the assessment of proteoglycan concentration and content in intervertebral degenerated discs (IDDs). METHODS T1ρ and T2-weighted MR images of 12 intervertebral discs (IVDs) from 3 harvested human lumbar spines (levels L1-L2 to L5-S1) were grouped across their degenerative grade (Pfirrmann scores) and analyzed using a 3T MRI scanner in the axial and sagittal views. Post-processing of axial T1ρ-weighted images was performed using a Wiener filter. Median axial T1ρ values for traced regions of interest (ROIs) on color maps were compared against ROIs in the corresponding location in the sagittal plane of each disc. Assessment of sulfated glycosaminoglycans (GAGs) content was also performed. RESULTS Comparison of post Wiener filtered mid-axial T1ρ values in the NP with corresponding mid-sagittal values revealed no statistical difference (P > 0.05). Higher axial T1ρ and biochemically measured GAGs content corresponded to a lower Pfirrmann grading of the IVDs. A strong association between the T1ρ values and the GAG contents was observed (r = 0.85, P = 0.0002). CONCLUSIONS The axial T1ρ methodology was validated against sagittal T1ρ providing an augmented spatial representation of IVD and can facilitate localization of focal degeneration within IVDs. T1ρ values provided a better granularity assessment of degenerative disc disease as it correlated with proteoglycan concentration. Thus, Wiener filtering is an effective tool for removing noise from T1ρ-weighted axial MR images.
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Affiliation(s)
- Kyle R Mulligan
- Orthopedics Research Laboratory of McGill University, Montreal General Hospital, 687 Pine Avenue West Suite L-4.65, Montreal, QC, H3A 1A1, Canada.,McGill Scoliosis and Spine Group, Montreal General Hospital, 1650 Cedar Avenue Office B5-158.4, Montreal, QC, H3G 1A4, Canada
| | - Catherine E Ferland
- McGill Scoliosis and Spine Group, Montreal General Hospital, 1650 Cedar Avenue Office B5-158.4, Montreal, QC, H3G 1A4, Canada.,Scoliosis and Spine Centre, Montreal Children Hospital, McGill University Health Centre, 2300 Tupper, C521, Montreal, H3H 2B1, Canada
| | - Rahul Gawri
- Orthopedics Research Laboratory of McGill University, Montreal General Hospital, 687 Pine Avenue West Suite L-4.65, Montreal, QC, H3A 1A1, Canada.,McGill Scoliosis and Spine Group, Montreal General Hospital, 1650 Cedar Avenue Office B5-158.4, Montreal, QC, H3G 1A4, Canada
| | - Arijitt Borthakur
- Department of Radiology, Center for Magnetic Resonance and Optical Imaging, University of Pennsylvania, B1 Stellar-Chance Laboratories, 422 Curie Blvd, Philadelphia, PA, 19104, USA
| | - Lisbet Haglund
- Orthopedics Research Laboratory of McGill University, Montreal General Hospital, 687 Pine Avenue West Suite L-4.65, Montreal, QC, H3A 1A1, Canada.,McGill Scoliosis and Spine Group, Montreal General Hospital, 1650 Cedar Avenue Office B5-158.4, Montreal, QC, H3G 1A4, Canada
| | - Jean A Ouellet
- Orthopedics Research Laboratory of McGill University, Montreal General Hospital, 687 Pine Avenue West Suite L-4.65, Montreal, QC, H3A 1A1, Canada. .,McGill Scoliosis and Spine Group, Montreal General Hospital, 1650 Cedar Avenue Office B5-158.4, Montreal, QC, H3G 1A4, Canada. .,Scoliosis and Spine Centre, Montreal Children Hospital, McGill University Health Centre, 2300 Tupper, C521, Montreal, H3H 2B1, Canada.
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Deng Z, Xie Q, Duan Z, Xiao P. Scintillation event energy measurement via a pulse model based iterative deconvolution method. Phys Med Biol 2013; 58:7815-27. [PMID: 24145134 DOI: 10.1088/0031-9155/58/21/7815] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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6
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Jin X, Katsevich A, Yu H, Wang G, Li L, Chen Z. Interior tomography with continuous singular value decomposition. IEEE TRANSACTIONS ON MEDICAL IMAGING 2012; 31:2108-2119. [PMID: 22907966 PMCID: PMC3773972 DOI: 10.1109/tmi.2012.2213304] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The long-standing interior problem has important mathematical and practical implications. The recently developed interior tomography methods have produced encouraging results. A particular scenario for theoretically exact interior reconstruction from truncated projections is that there is a known sub-region in the ROI. In this paper, we improve a novel continuous singular value decomposition (SVD) method for interior reconstruction assuming a known sub-region. First, two sets of orthogonal eigen-functions are calculated for the Hilbert and image spaces respectively. Then, after the interior Hilbert data are calculated from projection data through the ROI, they are projected onto the eigen-functions in the Hilbert space, and an interior image is recovered by a linear combination of the eigen-functions with the resulting coefficients. Finally, the interior image is compensated for the ambiguity due to the null space utilizing the prior sub-region knowledge. Experiments with simulated and real data demonstrate the advantages of our approach relative to the POCS type interior reconstructions.
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Affiliation(s)
- Xin Jin
- Department of Engineering Physics, Tsinghua University and Key Laboratory of Particle and Radiation Imaging (Tsinghua University), Ministry of Education, Beijing 100084, China
| | | | - Hengyong Yu
- Biomedical Imaging Division, VT-WFU School of Biomedical Engineering and Sciences, Virginia Tech, Blacksburg, VA 24060 USA; Wake Forest University Health Sciences, Winston-Salem, NC 27157 USA
| | - Ge Wang
- Biomedical Imaging Division, VT-WFU School of Biomedical Engineering and Sciences, Virginia Tech, Blacksburg, VA 24060 USA; Wake Forest University Health Sciences, Winston-Salem, NC 27157 USA
| | - Liang Li
- Department of Engineering Physics, Tsinghua University and Key Laboratory of Particle and Radiation Imaging (Tsinghua University), Ministry of Education, Beijing 100084, China
| | - Zhiqiang Chen
- Department of Engineering Physics, Tsinghua University and Key Laboratory of Particle and Radiation Imaging (Tsinghua University), Ministry of Education, Beijing 100084, China
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Xu Q, Mou X, Wang G, Sieren J, Hoffman EA, Yu H. Statistical interior tomography. IEEE TRANSACTIONS ON MEDICAL IMAGING 2011; 30:1116-28. [PMID: 21233044 PMCID: PMC3246757 DOI: 10.1109/tmi.2011.2106161] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
This paper presents a statistical interior tomography (SIT) approach making use of compressed sensing (CS) theory. With the projection data modeled by the Poisson distribution, an objective function with a total variation (TV) regularization term is formulated in the maximization of a posteriori (MAP) framework to solve the interior problem. An alternating minimization method is used to optimize the objective function with an initial image from the direct inversion of the truncated Hilbert transform. The proposed SIT approach is extensively evaluated with both numerical and real datasets. The results demonstrate that SIT is robust with respect to data noise and down-sampling, and has better resolution and less bias than its deterministic counterpart in the case of low count data.
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Affiliation(s)
- Qiong Xu
- Institute of Image Processing and Pattern Recognition, Xi’an Jiaotong University, Xi’an, Shaanxi 710049, China
| | - Xuanqin Mou
- Institute of Image Processing and Pattern Recognition, Xi’an Jiaotong University, Xi’an, Shaanxi 710049, China
| | - Ge Wang
- Biomedical Imaging Division, VT-WFU School of Biomedical Engineering and Sciences, Virginia Tech., Blacksburg, VA 24061 USA and with Wake Forest University Health Sciences, Winston-Salem, NC 27157 USA
| | - Jered Sieren
- Iowa Comprehensive Lung Imaging Center, Department of Radiology, University of Iowa, Iowa City, IA 52242 USA
| | - Eric A. Hoffman
- Iowa Comprehensive Lung Imaging Center, Department of Radiology, University of Iowa, Iowa City, IA 52242 USA
| | - Hengyong Yu
- Biomedical Imaging Division, VT-WFU School of Biomedical Engineering and Sciences, Virginia Tech., Blacksburg, VA 24061 USA, and with the Department of Radiology, Division of Radiologic Sciences, Wake Forest University Health Sciences, Winston-Salem, NC 27157 USA
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Stop Breast Cancer Now! Imagining Imaging Pathways Toward Search, Destroy, Cure, and Watchful Waiting of Premetastasis Breast Cancer. Breast Cancer 2010. [DOI: 10.1007/978-1-84996-314-5_10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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9
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Abstract
Currently, x-ray computed tomography (CT) requires source scanning so that projections can be collected from various orientations for image reconstruction. Limited by the scanning time, the temporal resolution of CT is often inadequate when rapid dynamics is involved in an object to be reconstructed. To meet this challenge, here the authors propose a scheme of multisource interior tomography for ultrafast imaging that reconstructs a relatively small region of interest (ROI). Specifically, such a ROI is irradiated in parallel with narrow x-ray beams defined by many source-detector pairs for data acquisition. This ROI can be then reconstructed using the interior tomography approach. To demonstrate the merits of this approach, the authors report interior reconstruction from in vivo lung CT data at a much reduced radiation dose, which is roughly proportional to the ROI size. The results suggest a scheme for ultrafast tomography (such as with a limited number of sources and in a scanning mode) to shorten data acquisition time and to suppress motion blurring.
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Affiliation(s)
- Ge Wang
- Biomedical Imaging Division, VT-WFU School of Biomedical Engineering and Sciences, Virginia Tech., Blacksburg, Virginia 24061, USA.
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Ohkubo M, Wada S, Ida S, Kunii M, Kayugawa A, Matsumoto T, Nishizawa K, Murao K. Determination of point spread function in computed tomography accompanied with verification. Med Phys 2009; 36:2089-97. [DOI: 10.1118/1.3123762] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Rollano-Hijarrubia E, Manniesing R, Niessen WJ. Selective deblurring for improved calcification visualization and quantification in carotid CT angiography: validation using micro-CT. IEEE TRANSACTIONS ON MEDICAL IMAGING 2009; 28:446-453. [PMID: 19244016 DOI: 10.1109/tmi.2008.2006529] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Visualization and quantification of small structures with computed tomography (CT) is hampered by the limited spatial resolution of the system. Histogram-based selective deblurring (HiSD) is a deconvolution method that restores small high-density structures, i.e., calcifications, of a CT image, using the high-intensity voxel information of the deconvolved image, while preserving the original hounsfield Units (HUs) in the remaining tissues. In this study, high resolution micro-CT data are used to validate the potential of HiSD to improve calcium visualization and quantification in the carotid arteries on in vivo contrast-enhanced CTA data. The evaluation is performed qualitatively and quantitatively on 15 atherosclerotic plaques obtained from ten different patients. HiSD in combination with vessel segmentation significantly improves calcification visualization and quantification on in vivo contrast-enhanced CT images. Calcification blur is reduced, while avoiding noise amplification and edge-ringing artifacts in the surrounding tissues. Calcification quantification errors are reduced by 23.5% on average.
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Affiliation(s)
- Empar Rollano-Hijarrubia
- Biomedical Imaging Group Rotterdam (BIGR), the Department of Radiology, Erasmus MC-University Medical Center of Rotterdam, 3015 GE Rotterdam, The Netherlands.
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Gratama van Andel HAF, Venema HW, Streekstra GJ, van Straten M, Majoie CBLM, den Heeten GJ, Grimbergen CA. Removal of bone in CT angiography by multiscale matched mask bone elimination. Med Phys 2007; 34:3711-23. [DOI: 10.1118/1.2767931] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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13
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Rollano-Hijarrubia E, Niessen W, Weinans H, van der Lugt A, Stokking R. Histogram-Based Selective Deblurring to Improve Computed Tomography Imaging of Calcifications. Invest Radiol 2007; 42:8-22. [PMID: 17213744 DOI: 10.1097/01.rli.0000248894.94242.96] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVES Computed tomography (CT) imaging of small high-density structures, eg, calcifications, is hampered by image blur. This study aims to deconvolve calcifications in the transverse and longitudinal directions while avoiding noise amplification and edge-ringing artifacts in the surrounding low-density structures. MATERIALS AND METHODS A method referred to as histogram-based selective deblurring (HiSD) has been developed to generate a restored image by combining the low-intensity (ie, Hounsfield Units) information of the original image with the high-intensity information of the deconvolved image. HiSD is evaluated on phantom and in vitro atherosclerotic plaque CT images by comparing the original and restored images with their corresponding reference micro-CT images both qualitatively and quantitatively. RESULTS HiSD reduces calcification blur in the transverse and longitudinal directions without introducing noise and ringing-artifacts in the surrounding tissues. Calcification area and volume measurements are significantly improved in the restored images (reducing on average overestimation by 32% and 83%, respectively). CONCLUSIONS HiSD significantly improves CT visualization and quantification of small high-density structures imaged in vitro.
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Affiliation(s)
- Empar Rollano-Hijarrubia
- Department of Radiology, Erasmus MC-University Medical Center Rotterdam, Rotterdam, The Netherlands.
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Rollano-Hijarrubia E, Stokking R, van der Meer F, Niessen WJ. Imaging of small high-density structures in CT A phantom study. Acad Radiol 2006; 13:893-908. [PMID: 16777564 DOI: 10.1016/j.acra.2006.03.009] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2006] [Revised: 03/16/2006] [Accepted: 03/18/2006] [Indexed: 11/25/2022]
Abstract
RATIONALE AND OBJECTIVES The aim of this work is to study how the limited spatial resolution of a computed tomographic (CT) system affects the imaging of small high-density structures. This knowledge is relevant not only to understand and interpret clinical data, but also to apply and develop quantification methods for calcifications and stented vessels. MATERIALS AND METHODS A dedicated phantom containing small differently sized aluminum cylinders was imaged on a 64-slice multidetector row CT (MDCT) while varying acquisition and reconstruction parameters from a high-resolution protocol. In addition, a bead phantom was imaged to estimate the point spread function (PSF) for the different parameter settings. The accuracy in determining object density and size was established for various imaging protocols and compared with simulations based on the estimated PSF. RESULTS Attenuation values and size measurements were accurate for objects larger than two times the size of the system PSF at the full-width-at-half-maximum. For smaller objects, attenuation values were increasingly underestimated and size was increasingly overestimated. The convolution kernel had the most influence on object signal and size. Use of edge-enhancing kernels yielded more accurate size measurements and higher signal for small objects. However, their application was constrained by noise amplification and edge-ringing artifacts, which led to lower signal-to-noise ratio, degrading the visualization of low densities and small high-density objects. CONCLUSION Results presented in this report provide insight into limitations in the quantification of small high-density structures and their effect on the visualization of surrounding tissues with recently developed MDCT systems.
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Affiliation(s)
- Empar Rollano-Hijarrubia
- Departments of Radiology and Medical Informatics, Erasmus MC-University Medical Center Rotterdam, Dr Molewaterplein 50, Rotterdam, Zuid-Holland 3015 GE, The Netherlands
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Saba OI, Hoffman EA, Reinhardt JM. Maximizing quantitative accuracy of lung airway lumen and wall measures obtained from X-ray CT imaging. J Appl Physiol (1985) 2003; 95:1063-75. [PMID: 12754180 DOI: 10.1152/japplphysiol.00962.2002] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
To objectively quantify airway geometry from three-dimensional computed tomographic (CT) images, an idealized (circular cross section) airway model is parameterized by airway luminal caliber, wall thickness, and tilt angle. Using a two-dimensional CT slice, an initial guess for the airway center, and the full-width-half-maximum principle, we form an estimate of inner and outer airway wall locations. We then fit ellipses to the inner and outer airway walls via a direct least squares fit and use the major and minor axes of the ellipses to estimate the tilt and in-plane rotation angles. Convolving the airway model, initialized with these estimates, with the three-dimensional scanner point-spread function forms the predicted image. The difference between predicted and actual images is minimized by refining the model parameter estimates via a multidimensional, unconstrained, nonlinear minimization routine. When optimization converges, airway model parameters estimate the airway inner and outer radii and tilt angle. Results using a Plexiglas phantom show that tilt angle is estimated to within +/-4 degrees and both inner and outer radii to within one-half pixel when a "standard" CT reconstruction kernel is used. By opening up the ability to measure airways that are not oriented perpendicular to the scanning plane, this method allows evaluation of a greater sampling of airways in a two-dimensional CT slice than previously possible. In addition, by combining the tilt-angle compensation with the deconvolution method, we provide significant improvement over the previous full-width-half-maximum method for assessing location of the luminal edge but not the outer edge of the airway wall.
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Affiliation(s)
- Osama I Saba
- Department of Biomedical Engineering, University of Iowa, Iowa City, IA 52242, USA
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van Straten M, Venema HW, Streekstra GJ, Reekers JA, den Heeten GJ, Grimbergen CA. Removal of arterial wall calcifications in CT angiography by local subtraction. Med Phys 2003; 30:761-70. [PMID: 12772982 DOI: 10.1118/1.1567271] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
CT Angiography (CTA) is an established technique for the minimally invasive imaging of arteries. The technique of maximum intensity projection (MIP) is often used to get a comprehensive overview of the vascular anatomy. On a MIP, however, arterial wall calcifications may hinder the visualization of the arterial lumen. These calcifications are in direct contact with the contrast-enhanced blood, which makes removal difficult. We present a local subtraction method for the automatic removal of these calcifications. In our approach a second CT scan has to be made, prior to contrast injection. The calcifications in both scans are registered prior to subtraction to compensate for displacements in between the two scans. Local subtraction results are compared with results obtained by thresholding. The method was tested in a phantom and with data from four patients. The phantom represented an artery with different types of stenosis. Data were used from patients for which CTA of the renal arteries was performed. For two patients the electrocardiogram (ECG) was recorded during the CTA examination, making retrospective cardiac gated reconstructions possible. Both the phantom and the patient study showed that the local subtraction method is capable of removing calcifications and visualizing the residual lumen. In the patient study it appeared that some artifacts remained for higher pitch values. We conclude that the local subtraction method is less subjective and more accurate than thresholding. Best results are obtained by use of a small pitch, at the expense of the volume covered during a single breath hold.
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Affiliation(s)
- Marcel van Straten
- Department of Medical Physics, Academic Medical Center, PO Box 22660 1100 DD, Amsterdam, The Netherlands.
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Whiting BR, McFarland EG, Brink JA. Influence of image acquisition parameters on CT artifacts and polyp depiction in spiral CT colonography: in vitro evaluation. Radiology 2000; 217:165-72. [PMID: 11012440 DOI: 10.1148/radiology.217.1.r00oc13165] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
PURPOSE To quantify the effects of spiral computed tomographic (CT) acquisition parameters on the magnitude of three-dimensional (3D) rippling artifacts and polyp depiction. MATERIALS AND METHODS An in vitro colon phantom was constructed with air-filled acrylic cylinders that contained synthetic polyps of 3-13 mm. The phantom was submerged in fluid and positioned at four angles of inclination relative to the z axis. Image data were acquired at collimation and pitch combinations of 3 mm and 1.67 and 5 mm and 1.6, respectively. Rippling artifacts were quantified by measuring the longitudinal variation of in-plane phantom edge width, and the influence of these artifacts on the depiction of pedunculated and sessile polyps was assessed qualitatively. RESULTS The in-plane magnitude of the rippling artifact was a function of the angle of inclination relative to the longitudinal axis and the table increment. The through-plane periodicity of the artifact was equal to one-half the table increment. CONCLUSION The table increment and angle of inclination of the surface of the object relative to the z axis determine the periodicity and magnitude of the rippling artifact at 3D spiral CT colonography. Although the depiction of small pedunculated polyps was not compromised, some sessile polyps were degraded by the artifact.
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Affiliation(s)
- B R Whiting
- Electronic Radiology Lab, and Abdominal Imaging Section, Mallinckrodt Institute of Radiology, 510 S Kingshighway Blvd, St Louis, MO 63110, USA.
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Abstract
It is shown that a spin-echo sequence may be used to acquire T(2)-weighted, high-resolution, high-SNR sections at quasi-real-time frame rates for interactive, diagnostic imaging. A single-shot fast spin-echo sequence was designed which employs driven equilibrium to realign transverse magnetization remaining at the final spin echo. Driven equilibrium is shown to improve T(2) contrast at a given TR, or conversely to reduce TR by approximately 1000 msec and thus increase temporal resolution while maintaining a given level of contrast. Wiener demodulation of k-space data prior to reconstruction is shown to reduce blurring caused by T(2)-decay while constraining noise often associated with other inverse filters. Images are continuously acquired, reconstructed, and displayed at rates of one image every one to two seconds, while section position and contrast may be altered interactively. The clinical utility of this method is demonstrated with applications to dynamic pelvic floor imaging and interactive obstetric imaging.
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Affiliation(s)
- R F Busse
- Magnetic Resonance Laboratory, Mayo Clinic, Rochester, Minnesota, USA
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19
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Measurement of layer thickness using spread width of longitudinal image in helical CT. Oral Radiol 1999. [DOI: 10.1007/bf02489646] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Harada T, Nishikawa K, Kuroyanagi K. Unsharp masking technique as a preprocessing filter for improvement of 3D-CT image of bony structure in the maxillofacial region. Oral Radiol 1998. [DOI: 10.1007/bf02492615] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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21
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Wang G, Vannier MW, Skinner MW, Cavalcanti MG, Harding GW. Spiral CT image deblurring for cochlear implantation. IEEE TRANSACTIONS ON MEDICAL IMAGING 1998; 17:251-262. [PMID: 9688157 DOI: 10.1109/42.700737] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Cochlear implantation is the standard treatment for profound hearing loss. Preimplantation and postimplantation spiral computed tomography (CT) is essential in several key clinical and research aspects. The maximum image resolution with commercial spiral CT scanners is insufficient to define clearly anatomical features and implant electrode positions in the inner ear. In this paper, we develop an expectation-maximization (EM)-like iterative deblurring algorithm to achieve spiral CT image super-resolution for cochlear implantation, assuming a spatially invariant linear spiral CT system with a three-dimensional (3-D) separable Gaussian point spread function (PSF). We experimentally validate the 3-D Gaussian blurring model via phantom measurement and profile fitting. The imaging process is further expressed as convolution of an isotropic 3-D Gaussian PSF and a blurred underlying volumetric image. Under practical conditions, an oblique reconstructed section is approximated as convolution of an isotropic two-dimensional (2-D) Gaussian PSF and the corresponding actual cross section. The spiral CT image deblurring algorithm is formulated with sieve and resolution kernels for suppressing noise and edge artifacts. A typical cochlear cross section is used for evaluation, demonstrating a resolution gain up to 30%40% according to the correlation criterion. Physical phantoms, preimplantation and postimplantation patients are reconstructed into volumes of 0.1-mm cubic voxels. The patient images are digitally unwrapped along the central axis of the cochlea and the implanted electrode array respectively, then oblique sections orthogonal to the central axis formed. After deblurring, representation of structural features is substantially improved in all the cases.
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Affiliation(s)
- G Wang
- Department of Radiology, University of Iowa, Iowa City 52242, USA.
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22
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Hopper KD, Keeton NC, Kasales CJ, Mahraj R, Van Slyke MA, Patrone SV, Singer PS, Tenhave TR. Utility of low mA 1.5 pitch helical versus conventional high mA abdominal CT. Clin Imaging 1998; 22:54-9. [PMID: 9421657 DOI: 10.1016/s0899-7071(97)00066-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The objective of this study was to evaluate the utility of a low mA 1.5 pitch helical versus conventional high mA conventional technique in abdominal computed tomography (CT). Twenty-five patients who had both a conventional high mA (> 300) and a 1.5 pitch low mA (80-125) helical CT within 3 months were selected for inclusion in the study. Patients were excluded who had a significant change in pathology between the two studies. The other parameters (injection rate, contrast type and volume, and filming window/level) were constant. The studies were randomized and blinded to five separate experienced readers who graded the studies by a variety of normal anatomical structures and pathological criteria. Overview questions also assessed noise, resolution, contrast, and overall quality. The abdominal wall/retroperitoneum and hiatal hernias were statistically better visualized on the conventional high mA studies. However, for all other normal anatomical and pathological sites, there was equivalent or better visualization on the helical versus the conventional CT examinations. The resolution of the helical studies was graded statistically better than the high mA conventional CT scans as was the amount of noise present on the images. While there was some advantage for conventional high mA CT with respect to contrast enhancement and low contrast sensitivity, these differences were not statistically significant. It appears from the data of this study that a low mA technique in evaluating the abdomen may be a useful option in performing routine abdominal CT. The radiation dose savings to the patient is significant and there appears to be little degradation of image quality using a low mA 1.5 helical versus mA conventional CT technique.
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Affiliation(s)
- K D Hopper
- Department of Radiology, Penn State University, Hershey, Pennsylvania 17033, USA
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23
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Sakai O, Shen Y, Takata Y, Furuse M. The use of deblurring technique for improving the longitudinal resolution in helical CT of the head and neck region. Comput Med Imaging Graph 1997; 21:153-64. [PMID: 9258593 DOI: 10.1016/s0895-6111(97)00004-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
We evaluated the use of deblurring technique by digital deconvolution for improving the longitudinal resolution in helical CT in a phantom and CT images of head and neck patients. After performing the helical scanning, overlapped axial images were reconstructed at 1/10 of the actual collimation. Then, the deblurring technique was performed. Results revealed that the resolution of slice profiles was improved after deblurring. Further, the longitudinal resolution increased as the strength of the deconvolution increased, at the expense of an increase in helical artifacts. The sharpness and visualization of horizontally running structures were improved in the reconstructed MPR, MPVR, MIP and 3D images in both the phantom and the images of all patients. Also, visualization of the peripheral vessels in CTAs was improved.
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Affiliation(s)
- O Sakai
- Department of Radiology, Jichi Medical School and Hospital, Tochigi, Japan
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Abstract
Magnetic resonance imaging provides clinically useful information in assessing the elbow joint. Superior depiction of muscles, ligaments, and tendons as well as the ability to directly visualize nerves, bone marrow, and hyaline cartilage are advantages of magnetic resonance imaging relative to conventional imaging techniques. Ongoing improvements in surface coil design and newer pulse sequences have resulted in higher quality magnetic resonance images of the elbow. Traumatic and degenerative disorders of the elbow are well seen with MR imaging. The sequelae of medial traction and lateral compression from valgus stress include medial collateral ligament injury, common flexor tendon pathology, medial traction spurs, ulnar neuropathy, and osteochondritis dissecans. These conditions as well as lateral collateral ligament injury and lateral epicondylitis may be characterized with magnetic resonance imaging. Posttraumatic osseous abnormalities well seen by magnetic resonance imaging include radiographically occult fractures, stress fractures, bone contusions, and apophyseal avulsions. Magnetic resonance imaging also can be used to assess cartilaginous extension of fractures in children. Intraarticular loose bodies can be identified with magnetic resonance imaging, especially if fluid or contrast material is present within the elbow joint. Biceps and triceps tendon injuries can be diagnosed and characterized. Magnetic resonance imaging also can provide additional information regarding entrapment neuropathies about the elbow. Magnetic resonance imaging is perhaps most useful when patients have not responded to conservative therapy and therefore surgery and additional diagnoses are being considered.
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Affiliation(s)
- R C Fritz
- National Orthopaedic Imaging Associates, Greenbrae, CA 94904, USA
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Wang G, Skinner MW, Vannier MW. Temporal bone volumetric image deblurring in spiral computed tomography scanning. Acad Radiol 1995; 2:888-95. [PMID: 9419656 DOI: 10.1016/s1076-6332(05)80069-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
RATIONALE AND OBJECTIVES We developed a method for volumetric image deblurring in spiral (helical) computed tomography (CT) scanning with a three-dimensional (3D) Gaussian point spread function (PSF) to improve the quality of temporal bone spiral CT images for assessing the position of cochlear implants electrodes. METHODS A patient was scanned after cochlear implantation, and the temporal bone was reconstructed into a volume with 128 voxels per dimension, 0.1 mm per voxel side, and x 10 gray-scale expansion. The 3D PSF in spiral CT imaging was assumed to be Gaussian separable transversely and longitudinally. Standard deviations of the PSF were derived and subjectively adjusted. The image was then deconvolved using Wiener filtering and maximum-likelihood deconvolution methods. Image quality was assessed both visually and quantitatively using cross-sectional area at half of the maximum (CAHM) of the implanted array as the figure of merit. RESULTS Substantial image deblurring was achieved via deconvolution. Subjectively, anatomic structures were more clearly shown. Deconvolution reduced the CAHM by approximately one third, on average. Three-dimensional deconvolution had better image quality than two-dimensional deconvolution. The maximum-likelihood method produced superior image quality but took longer to process relative to Wiener filtering. CONCLUSION Volumetric image deblurring is practical with a Gaussian PSF. The maximum-likelihood method is preferred if time permits. Deconvolution facilitates the study of fine details of the temporal bone and cochlear implant.
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Affiliation(s)
- G Wang
- Mallinckrodt Institute of Radiology, St. Louis, MO 63110, USA
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