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Li A, Xie Q, Huang J, Xiao P. Evaluation of applying space-variant resolution modeling to attenuation correction in PET. Biomed Phys Eng Express 2022; 8:045009. [PMID: 35623332 DOI: 10.1088/2057-1976/ac741c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Attenuation correction aims to recover the underestimated tracer uptake and improve the image contrast recovery in positron emission tomography (PET). However, traditional ray-tracing-based projection of attenuation maps is inaccurate as some physical effects are not considered, such as finite crystal size, inter-crystal penetration and inter-crystal scatter. In this study, we evaluated the effects of applying resolution modeling (RM) to attenuation correction by implementing space-variant RM to complement physical effects which are usually omitted in the traditional projection model. We verified this method on a brain PET scanner developed by our group, in both Monte Carlo simulation and real-world data, in comparison with space-invariant Gaussian RM, average-depth-of-interaction, and multi-ray tracing methods. The results indicate that the space-variant RM is superior in terms of artifacts reduction and contrast recovery.
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Affiliation(s)
- Ang Li
- College of life science and technology, Huazhong University of Science and Technology, 1037 Luoyu Road, Hongshan District, Wuhan City, Hubei Province, China, Wuhan, 430074, CHINA
| | - Qingguo Xie
- Biomedical Engineering Department, Huazhong University of Science and Technology, Wuhan, Hubei 430074, Wuhan, Hubei, 430074, CHINA
| | - Jing Huang
- Huazhong University of Science and Technology, 1037 Luoyu Road, Hongshan District, Wuhan City, Hubei Province, China, Wuhan, 430074, CHINA
| | - Peng Xiao
- Biomedical Engineering Department, Huazhong University of Science and Technology, Wuhan, Hubei 430074, Wuhan, Hubei, 430074, CHINA
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Morawitz J, Martin O, Boos J, Sawicki LM, Wingendorf K, Sedlmair M, Mamlins E, Antke C, Antoch G, Schaarschmidt BM. Impact of Different Metal Artifact Reduction Techniques on Attenuation Correction of Normal Organs in 18F-FDG-PET/CT. Diagnostics (Basel) 2022; 12:diagnostics12020375. [PMID: 35204466 PMCID: PMC8870731 DOI: 10.3390/diagnostics12020375] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Revised: 01/20/2022] [Accepted: 01/28/2022] [Indexed: 02/04/2023] Open
Abstract
Purpose: To evaluate the impact of different metal artifact reduction algorithms on Hounsfield units (HU) and the standardized uptake value (SUV) in normal organs in patients with different metal implants. Methods: This study prospectively included 66 patients (mean age of 66.02 ± 13.1 years) with 87 different metal implants. CT image reconstructions were performed using weighted filtered back projection (WFBP) as the standard method, metal artifact reduction in image space (MARIS), and an iterative metal artifacts reduction (iMAR) algorithm for large implants. These datasets were used for PET attenuation correction. HU and SUV measurements were performed in nine predefined anatomical locations: liver, lower lung lobes, descending aorta, thoracic vertebral body, autochthonous back muscles, pectoral muscles, and internal jugular vein. Differences between HU and SUV measurements were compared using paired t-tests. The significance level was determined as p = 0.017 using Bonferroni correction. Results: No significant differences were observed between reconstructed images using iMAR and WFBP concerning HU and SUV measurements in liver (HU: p = 0.055; SUVmax: p = 0.586), lung (HU: p = 0.276; SUVmax: p = 1.0 for the right side and HU: p = 0.630; SUVmax: p = 0.109 for the left side), descending aorta (HU: p = 0.333; SUVmax: p = 0.083), thoracic vertebral body (HU: p = 0.725; SUVmax: p = 0.392), autochthonous back muscles (HU: p = 0.281; SUVmax: p = 0.839), pectoral muscles (HU: p = 0.481; SUVmax: p = 0.277 for the right side and HU: p = 0.313; SUVmax: p = 0.859 for the left side), or the internal jugular vein (HU: p = 0.343; SUVmax: p = 0.194). Conclusion: Metal artifact reduction algorithms such as iMAR do not alter the data information of normal organs not affected by artifacts.
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Affiliation(s)
- Janna Morawitz
- Department of Diagnostic and Interventional Radiology, Medical Faculty, University Dusseldorf, D-40225 Dusseldorf, Germany; (O.M.); (J.B.); (L.M.S.); (K.W.); (G.A.)
- Correspondence: ; Tel.: +49-2118117552; Fax: +49-2118116145
| | - Ole Martin
- Department of Diagnostic and Interventional Radiology, Medical Faculty, University Dusseldorf, D-40225 Dusseldorf, Germany; (O.M.); (J.B.); (L.M.S.); (K.W.); (G.A.)
| | - Johannes Boos
- Department of Diagnostic and Interventional Radiology, Medical Faculty, University Dusseldorf, D-40225 Dusseldorf, Germany; (O.M.); (J.B.); (L.M.S.); (K.W.); (G.A.)
| | - Lino M. Sawicki
- Department of Diagnostic and Interventional Radiology, Medical Faculty, University Dusseldorf, D-40225 Dusseldorf, Germany; (O.M.); (J.B.); (L.M.S.); (K.W.); (G.A.)
| | - Katrin Wingendorf
- Department of Diagnostic and Interventional Radiology, Medical Faculty, University Dusseldorf, D-40225 Dusseldorf, Germany; (O.M.); (J.B.); (L.M.S.); (K.W.); (G.A.)
| | - Martin Sedlmair
- Department of Computed Tomography, Siemens Healthineers GmbH, D-91301 Forchheim, Germany;
| | - Eduards Mamlins
- Department of Nuclear Medicine, Medical Faculty, University Dusseldorf, D-40225 Dusseldorf, Germany; (E.M.); (C.A.)
| | - Christina Antke
- Department of Nuclear Medicine, Medical Faculty, University Dusseldorf, D-40225 Dusseldorf, Germany; (E.M.); (C.A.)
| | - Gerald Antoch
- Department of Diagnostic and Interventional Radiology, Medical Faculty, University Dusseldorf, D-40225 Dusseldorf, Germany; (O.M.); (J.B.); (L.M.S.); (K.W.); (G.A.)
| | - Benedikt M. Schaarschmidt
- Institute of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, D-45147 Essen, Germany;
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Haemels M, Vandendriessche D, De Geeter J, Velghe J, Vandekerckhove M, De Geeter F. Quantitative Effect of Metal Artefact Reduction on CT-based attenuation correction in FDG PET/CT in patients with hip prosthesis. EJNMMI Phys 2021; 8:67. [PMID: 34626242 PMCID: PMC8502194 DOI: 10.1186/s40658-021-00414-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2020] [Accepted: 09/17/2021] [Indexed: 01/14/2023] Open
Abstract
BACKGROUND Metal artefact reduction (MAR) techniques still are in limited use in positron emission tomography/computed tomography (PET/CT). This study aimed to investigate the effect of Smart MAR on quantitative PET analysis in the vicinity of hip prostheses. MATERIALS AND METHODS Activities were measured on PET/CT images in 6 sources with tenfold activity concentration contrast to background, attached to the head, neck and the major trochanter of a human cadaveric femur, and in the same sources in similar locations after a hip prosthesis (titanium cup, ceramic head, chrome-cobalt stem) had been inserted into the femur. Measurements were compared between PET attenuation corrected using either conventional or MAR CT. In 38 patients harbouring 49 hip prostheses, standardized uptake values (SUV) in 6 periprosthetic regions and the bladder were compared between PET attenuation corrected with either conventional or MAR CT. RESULTS Using conventional CT, measured activity decreased with 2 to 13% when the prosthesis was inserted. Use of MAR CT increased measured activity by up to 11% compared with conventional CT and reduced the relative difference with the reference values to under 5% in all sources. In all regions, to the exception of the prosthesis shaft, SUVmean increased significantly (p < 0.001) by use of MAR CT. Median (interquartile range) percentual increases of SUVmean were 1.4 (0.0-4.2), 4.0 (1.8-7.8), 7.8 (4.1-12.4), 1.5 (0.0-3.2), 1.4 (0.8-2.8) in acetabulum, lateral neck, medial neck, lateral diaphysis and medial diaphysis, respectively. Except for the shaft, the coefficient of variation did not increase significantly. Except for the erratic changes in the prosthesis shaft, decreases in SUVmean were rare and small. Bladder SUVmean increased by 0.9% in patients with unilateral prosthesis and by 4.1% in patients with bilateral prosthesis. CONCLUSIONS In a realistic hip prosthesis phantom, Smart MAR restores quantitative accuracy by recovering counts in underestimated sources. In patient studies, Smart MAR increases SUV in all areas surrounding the prosthesis, most markedly in the femoral neck region. This proves that underestimation of activity in the PET image is the most prevalent effect due to metal artefacts in the CT image in patients with hip prostheses. Smart MAR increases SUV in the urinary bladder, indicating effects at a distance from the prosthesis.
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Affiliation(s)
- Maarten Haemels
- Department of Nuclear Medicine, Algemeen Ziekenhuis Sint-Jan Brugge-Oostende, Ruddershove 10, 8000, Brugge, Belgium
| | - Delphine Vandendriessche
- Department of Nuclear Medicine, Algemeen Ziekenhuis Sint-Jan Brugge-Oostende, Ruddershove 10, 8000, Brugge, Belgium
| | - Jeroen De Geeter
- ELEC Department, Faculty of Applied Sciences, Vrije Universiteit Brussel, Building K - Room K.6.55/D2, Pleinlaan 2, 1050, Brussel, Belgium
| | - James Velghe
- Nuclear Technology Center, UHasselt, Campus Diepenbeek, Agoralaan Building D, 3590, Diepenbeek, Belgium
| | - Maxence Vandekerckhove
- Department of Orthopedics, Algemeen Ziekenhuis Sint-Jan Brugge-Oostende, Ruddershove 10, 8000, Brugge, Belgium
| | - Frank De Geeter
- Department of Nuclear Medicine, Algemeen Ziekenhuis Sint-Jan Brugge-Oostende, Ruddershove 10, 8000, Brugge, Belgium.
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Desai SD. Novel 3-fold metal artifact reduction method for CT images. Biomed Signal Process Control 2021. [DOI: 10.1016/j.bspc.2021.102967] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Kovacs DG, Ladefoged CN, Berthelsen AK, Fischer BM, Andersen FL. Combined dual energy and iterative metal artefact reduction for PET/CT in head and neck cancer. Phys Med Biol 2020; 65. [PMID: 33086211 DOI: 10.1088/1361-6560/abc366] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Accepted: 10/21/2020] [Indexed: 11/11/2022]
Abstract
Metal artefacts in PET/CT images hamper diagnostic accuracy in head and neck cancer (HNC). The aim of this study is to characterise the clinical effects of metal artefacts on PET/CT in HNC and to inform decision-making concerning implementation of MAR techniques. We study a combined dual energy CT and inpainting-based metal artefact reduction (DECT-I-MAR) technique for PET/CT in three settings: (A) A dental phantom with a removable amalgam-filled tooth to evaluate the PET error in comparison to a known reference. (B) PET-positive patients with metallic implants to demostrate the relationship between CT metal artefacts and PET error. (C) Metabolic tumour volumes (MTVs) delineated in PET-positive patients with metal implants to evaluate the clinical impact. In (A) DECT-I-MAR reduced the PET error significantly. In (B) we demonstrate an increasing PET error with increasing CT artefact severity in patients. In (C) it is shown that the presence of artefacts in the same axial slices as the tumour significantly decrease biomarker stability and increase delineation variability. This work shows the practical feasibility of DECT-I-MAR based PET/CT imaging, and indicates a positive clinical impact of using the technique routinely for HNC patients. The impact of CT artefacts on PET is considerable, especially in workflows where quantitative PET biomarkers and tumour volumes are used. In such cases, and for patients with tumours in proximity of metals, we recommend that a MAR technique for PET/CT is employed.
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Affiliation(s)
- David Gergely Kovacs
- Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, Kobenhavn, DENMARK
| | - Claes Nøhr Ladefoged
- Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, Blegdamsvej 9, Kobenhavn, 2100, DENMARK
| | - Anne Kiil Berthelsen
- Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, Kobenhavn, Østerbro, DENMARK
| | - Barbara Malene Fischer
- Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, Kobenhavn, Østerbro, DENMARK
| | - Flemming L Andersen
- Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, Kobenhavn, DENMARK
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Ziv O, Goldberg SN, Nissenbaum Y, Sosna J, Weiss N, Azhari H. In vivo noninvasive three-dimensional (3D) assessment of microwave thermal ablation zone using non-contrast-enhanced x-ray CT. Med Phys 2020; 47:4721-4734. [PMID: 32745257 DOI: 10.1002/mp.14428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Revised: 07/20/2020] [Accepted: 07/22/2020] [Indexed: 11/08/2022] Open
Abstract
PURPOSE To develop an image processing methodology for noninvasive three-dimensional (3D) quantification of microwave thermal ablation zones in vivo using x-ray computed tomography (CT) imaging without injection of a contrast enhancing material. METHODS Six microwave (MW) thermal ablation procedures were performed in three pigs. The ablations were performed with a constant heating duration of 8 min and power level of 30 W. During the procedure images from sixty 1 mm thick slices were acquired every 30 s. At the end of all ablation procedures for each pig, a contrast-enhanced scan was acquired for reference. Special algorithms for addressing challenges stemming from the 3D in vivo setup and processing the acquired images were prepared. The algorithms first rearranged the data to account for the oblique needle orientation and for breathing motion. Then, the gray level variance changes were analyzed, and optical flow analysis was applied to the treated volume in order to obtain the ablation contours and reconstruct the ablation zone in 3D. The analysis also included a special correction algorithm for eliminating artifacts caused by proximal major blood vessels and blood flow. Finally, 3D reference reconstructions from the contrast-enhanced scan were obtained for quantitative comparison. RESULTS For four ablations located >3 mm from a large blood vessel, the mean dice similarity coefficient (DSC) and the mean absolute radial discrepancy between the contours obtained from the reference contrast-enhanced images and the contours produced by the algorithm were 0.82 ± 0.03 and 1.92 ± 1.47 mm, respectively. In two cases of ablation adjacent to large blood vessels, the average DSC and discrepancy were: 0.67 ± 0.6 and 2.96 ± 2.15 mm, respectively. The addition of the special correction algorithm utilizing blood vessels mapping improved the mean DSC and the mean absolute discrepancy to 0.85 ± 0.02 and 1.19 ± 1.00 mm, respectively. CONCLUSIONS The developed algorithms provide highly accurate detailed contours in vivo (average error < 2.5 mm) and cope well with the challenges listed above. Clinical implementation of the developed methodology could potentially provide real time noninvasive 3D accurate monitoring of MW thermal ablation in-vivo, provided that the radiation dose can be reduced.
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Affiliation(s)
- Omri Ziv
- Department of Biomedical Engineering, Technion - IIT, Haifa, 32000, Israel
| | - S Nahum Goldberg
- Department of Radiology, Hadassah Medical Center, Hebrew University, Jerusalem, 91120, Israel.,Department of Radiology, Beth Israel Deaconess Medical Center, Boston, MA, 02215, USA
| | - Yitzhak Nissenbaum
- Department of Radiology, Hadassah Medical Center, Hebrew University, Jerusalem, 91120, Israel
| | - Jacob Sosna
- Department of Radiology, Hadassah Medical Center, Hebrew University, Jerusalem, 91120, Israel.,Department of Radiology, Beth Israel Deaconess Medical Center, Boston, MA, 02215, USA
| | - Noam Weiss
- Department of Biomedical Engineering, Technion - IIT, Haifa, 32000, Israel
| | - Haim Azhari
- Department of Biomedical Engineering, Technion - IIT, Haifa, 32000, Israel
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Martin O, Aissa J, Boos J, Wingendorf K, Latz D, Buchbender C, Gaspers S, Antke C, Sedlmair M, Antoch G, Schaarschmidt BM. Impact of different metal artifact reduction techniques on attenuation correction in 18F-FDG PET/CT examinations. Br J Radiol 2019; 93:20190069. [PMID: 31642702 DOI: 10.1259/bjr.20190069] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
OBJECTIVE To evaluate the impact of different metal artifact reduction (MAR) algorithms on Hounsfield unit (HU) and standardized uptake values (SUV) in a phantom setting and verify these results in patients with metallic implants undergoing oncological PET/CT examinations. METHODS AND MATERIALS In this prospective study, PET-CT examinations of 28 oncological patients (14 female, 14 male, mean age 69.5 ± 15.2y) with 38 different metal implants were included. CT datasets were reconstructed using standard weighted filtered back projection (WFBP) without MAR, MAR in image space (MARIS) and iterative MAR (iMAR, hip algorithm). The three datasets were used for PET attenuation correction. SUV and HU measurements were performed at the site of the most prominent bright and dark band artifacts. Differences between HU and SUV values across the different reconstructions were compared using paired t-tests. Bonferroni correction was used to prevent alpha-error accumulation (p < 0.017). RESULTS For bright band artifacts, MARIS led to a non-significant mean decrease of 12.0% (345 ± 315 HU) in comparison with WFBP (391 ± 293 HU), whereas iMAR led to a significant decrease of 68.3% (125 ± 185 HU, p < 0.017). For SUVmean, MARIS showed no significant effect in comparison with WFBP (WFBP: 0.99 ± 0.40, MARIS: 0.96 ± 0.39), while iMAR led to a significant decrease of 11.1% (0.88 ± 0.35, p < 0.017). Similar results were observed for dark band artifacts. CONCLUSION iMAR significantly reduces artifacts caused by metal implants in CT and thus leads to a significant change of SUV measurements in bright and dark band artifacts compared with WFBP and MARIS, thus probably improving PET quantification. ADVANCES IN KNOWLEDGE The present work indicates that MAR algorithms such as iMAR algorithm in integrated PET/CT scanners are useful to improve CT image quality as well as PET quantification in the evaluation of tracer uptake adjacent to large metal implants. A detailed analysis of oncological patients with various large metal implants using different MAR algorithms in PET/CT has not been conducted yet.
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Affiliation(s)
- Ole Martin
- Department of Diagnostic and Interventional Radiology, University Dusseldorf, Medical Faculty, D-40225 Dusseldorf, Germany
| | - Joel Aissa
- Department of Diagnostic and Interventional Radiology, University Dusseldorf, Medical Faculty, D-40225 Dusseldorf, Germany
| | - Johannes Boos
- Department of Diagnostic and Interventional Radiology, University Dusseldorf, Medical Faculty, D-40225 Dusseldorf, Germany
| | - Katrin Wingendorf
- Department of Diagnostic and Interventional Radiology, University Dusseldorf, Medical Faculty, D-40225 Dusseldorf, Germany
| | - David Latz
- Clinic for Trauma and Hand Surgery, University Dusseldorf, Medical Faculty, D-40225 Dusseldorf, Germany
| | - Christian Buchbender
- Department of Diagnostic and Interventional Radiology, University Dusseldorf, Medical Faculty, D-40225 Dusseldorf, Germany
| | - Susanne Gaspers
- Clinic for Nuclear Medicine, University Dusseldorf, Medical Faculty, D-40225 Dusseldorf, Germany
| | - Christina Antke
- Clinic for Nuclear Medicine, University Dusseldorf, Medical Faculty, D-40225 Dusseldorf, Germany
| | - Martin Sedlmair
- Department of Computed Tomography, Siemens Healthineers GmH, Forchheim, Germany
| | - Gerald Antoch
- Department of Diagnostic and Interventional Radiology, University Dusseldorf, Medical Faculty, D-40225 Dusseldorf, Germany
| | - Benedikt M Schaarschmidt
- Department of Diagnostic and Interventional Radiology, University Dusseldorf, Medical Faculty, D-40225 Dusseldorf, Germany
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Rodríguez-Gallo Y, Orozco-Morales R, Pérez-Díaz M. Gradient image smoothing for metal artifact reduction (GISMAR) in computed tomography. Biomed Phys Eng Express 2019. [DOI: 10.1088/2057-1976/ab0c4d] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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9
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Ziv O, Goldberg SN, Nissenbaum Y, Sosna J, Weiss N, Azhari H. Optical flow and image segmentation analysis for noninvasive precise mapping of microwave thermal ablation in X-ray CT scans - ex vivo study. Int J Hyperthermia 2017; 34:744-755. [PMID: 28866952 DOI: 10.1080/02656736.2017.1375160] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
PURPOSE To develop image processing algorithms for noninvasive mapping of microwave thermal ablation using X-ray CT. METHODS Ten specimens of bovine liver were subjected to microwave ablation (20-80 W, 8 min) while scanned by X-ray CT at 5 s intervals. Specimens were cut and manually traced by two observers. Two algorithms were developed and implemented to map the ablation zone. The first algorithm utilises images segmentation of Hounsfield units changes (ISHU). The second algorithm utilises radial optical flow (ROF). Algorithm sensitivity to spatiotemporal under-sampling was assessed by decreasing the acquisition rate and reducing the number of acquired projections used for image reconstruction in order to evaluate the feasibility of implementing radiation reduction techniques. RESULTS The average radial discrepancy between the ISHU and ROF contours and the manual tracing were 1.04±0.74 and 1.16±0.79mm, respectively. When diluting the input data, the ISHU algorithm retained its accuracy, ranging from 1.04 to 1.79mm. By contrast, the ROF algorithm performance became inconsistent at low acquisition rates. Both algorithms were not sensitive to projections reduction, (ISHU: 1.24±0.83mm, ROF: 1.53±1.15mm, for reduction by eight fold). Ablations near large blood vessels affected the ROF algorithm performance (1.83±1.30mm; p < 0.01), whereas ISHU performance remained the same. CONCLUSION The two suggested noninvasive ablation mapping algorithms can provide highly accurate contouring of the ablation zone at low scan rates. The ISHU algorithm may be more suitable for clinical practice as it appears more robust when radiation dose reduction strategies are employed and when the ablation zone is near large blood vessels.
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Affiliation(s)
- Omri Ziv
- a Department of Biomedical Engineering , Technion - IIT , Haifa , Israel
| | - S Nahum Goldberg
- b Department of Radiology , Hadassah Medical Center, Hebrew University , Jerusalem , Israel.,c Department of Radiology , Beth Israel Deaconess Medical Center , Boston , MA , USA
| | - Yitzhak Nissenbaum
- b Department of Radiology , Hadassah Medical Center, Hebrew University , Jerusalem , Israel
| | - Jacob Sosna
- b Department of Radiology , Hadassah Medical Center, Hebrew University , Jerusalem , Israel.,c Department of Radiology , Beth Israel Deaconess Medical Center , Boston , MA , USA
| | - Noam Weiss
- a Department of Biomedical Engineering , Technion - IIT , Haifa , Israel
| | - Haim Azhari
- a Department of Biomedical Engineering , Technion - IIT , Haifa , Israel
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Zhou PU, Tang J, Zhang D, Li G. False-positive 18F-fluorodeoxyglucose positron emission tomography/computed tomography in a patient with metallic implants following chondrosarcoma resection. Mol Clin Oncol 2016; 4:830-832. [PMID: 27123290 DOI: 10.3892/mco.2016.801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Accepted: 02/22/2016] [Indexed: 11/05/2022] Open
Abstract
Positron emission tomography (PET) with fluorine-18-labeled fluorodeoxyglucose (18F-FDG) has been used for the staging and evaluation of recurrence in cancer patients. We herein report a false-positive result of 18F-FDG PET/computed tomography (CT) scan in a patient following chondrosarcoma resection and metallic implanting. A 35-year-old male patient with chondrosarcoma of the left iliac bone underwent radical resection, metal brace implanting and radiotherapy. A high uptake of 18F-FDG was observed in the metallic implants and adjacent tissue during PET/CT scanning in the 5th year of follow-up. Tissue biopsy and follow-up examination identified no tumor recurrence or infection at these sites, suggesting that the results of 18F-FDG PET/CT must be interpreted with caution in cancer patients with metallic implants.
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Affiliation(s)
- P U Zhou
- Institute for Cancer Research in People's Liberation Army, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, P.R. China
| | - Jinliang Tang
- Department of Radiology, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, P.R. China
| | - Dong Zhang
- Department of Pathology, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, P.R. China
| | - Guanghui Li
- Institute for Cancer Research in People's Liberation Army, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, P.R. China
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Wuest W, May MS, Brand M, Bayerl N, Krauss A, Uder M, Lell M. Improved Image Quality in Head and Neck CT Using a 3D Iterative Approach to Reduce Metal Artifact. AJNR Am J Neuroradiol 2015; 36:1988-93. [PMID: 26272971 DOI: 10.3174/ajnr.a4386] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2014] [Accepted: 02/09/2015] [Indexed: 02/02/2023]
Abstract
BACKGROUND AND PURPOSE Metal artifacts from dental fillings and other devices degrade image quality and may compromise the detection and evaluation of lesions in the oral cavity and oropharynx by CT. The aim of this study was to evaluate the effect of iterative metal artifact reduction on CT of the oral cavity and oropharynx. MATERIALS AND METHODS Data from 50 consecutive patients with metal artifacts from dental hardware were reconstructed with standard filtered back-projection, linear interpolation metal artifact reduction (LIMAR), and iterative metal artifact reduction. The image quality of sections that contained metal was analyzed for the severity of artifacts and diagnostic value. RESULTS A total of 455 sections (mean ± standard deviation, 9.1 ± 4.1 sections per patient) contained metal and were evaluated with each reconstruction method. Sections without metal were not affected by the algorithms and demonstrated image quality identical to each other. Of these sections, 38% were considered nondiagnostic with filtered back-projection, 31% with LIMAR, and only 7% with iterative metal artifact reduction. Thirty-three percent of the sections had poor image quality with filtered back-projection, 46% with LIMAR, and 10% with iterative metal artifact reduction. Thirteen percent of the sections with filtered back-projection, 17% with LIMAR, and 22% with iterative metal artifact reduction were of moderate image quality, 16% of the sections with filtered back-projection, 5% with LIMAR, and 30% with iterative metal artifact reduction were of good image quality, and 1% of the sections with LIMAR and 31% with iterative metal artifact reduction were of excellent image quality. CONCLUSIONS Iterative metal artifact reduction yields the highest image quality in comparison with filtered back-projection and linear interpolation metal artifact reduction in patients with metal hardware in the head and neck area.
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Affiliation(s)
- W Wuest
- From the Radiological Institute (W.W., M.S.M., M.B., N.B., M.U., M.L.), Friedrich-Alexander-University-Erlangen-Nuremberg, Erlangen, Germany
| | - M S May
- From the Radiological Institute (W.W., M.S.M., M.B., N.B., M.U., M.L.), Friedrich-Alexander-University-Erlangen-Nuremberg, Erlangen, Germany
| | - M Brand
- From the Radiological Institute (W.W., M.S.M., M.B., N.B., M.U., M.L.), Friedrich-Alexander-University-Erlangen-Nuremberg, Erlangen, Germany
| | - N Bayerl
- From the Radiological Institute (W.W., M.S.M., M.B., N.B., M.U., M.L.), Friedrich-Alexander-University-Erlangen-Nuremberg, Erlangen, Germany
| | - A Krauss
- Medical Imaging (A.K.), Siemens Healthcare, Erlangen, Germany
| | - M Uder
- From the Radiological Institute (W.W., M.S.M., M.B., N.B., M.U., M.L.), Friedrich-Alexander-University-Erlangen-Nuremberg, Erlangen, Germany
| | - M Lell
- From the Radiological Institute (W.W., M.S.M., M.B., N.B., M.U., M.L.), Friedrich-Alexander-University-Erlangen-Nuremberg, Erlangen, Germany
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Abstract
Total joint replacement surgery is being performed on an increasingly large part of the population. Clinical longevity of implants depends on their osseointegration, which is influenced by the load, the characteristics of the implant and the bone-implant interface, as well as by the quality and quantity of the surrounding bone. Aseptic loosening due to periprosthetic osteolysis is the most frequent known cause of implant failure. Wear of prosthetic materials results in the formation of numerous particles of debris that cause a complex biological response. Dual-energy X-ray Absorptiometry (DXA) is regarded as an accurate method to evaluate Bone Mineral Density (BMD) around hip or knee prostheses. Further data may be provided by a new device, the Bone Microarchitecture Analysis (BMA), which combines bone microarchitecture quantification and ultra high resolution osteo-articular imaging. Pharmacological strategies have been developed to prevent bone mass loss and to extend implant survival. Numerous trials with bisphosphonates show a protective effect on periprosthetic bone mass, up to 72 months after arthroplasty. Strontium ranelate has been demonstrated to increase the osseointegration of titanium implants in treated animals with improvement of bone microarchitecture and bone biomaterial properties.
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Affiliation(s)
- Loredana Cavalli
- Department of Surgery and Translational Medicine, University of Florence, Florence, 50139, Italy
| | - Maria Luisa Brandi
- Department of Surgery and Translational Medicine, University of Florence, Florence, 50139, Italy
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The effect of metal artefact reduction on CT-based attenuation correction for PET imaging in the vicinity of metallic hip implants: a phantom study. Ann Nucl Med 2014; 28:540-50. [PMID: 24710757 DOI: 10.1007/s12149-014-0844-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2013] [Accepted: 03/17/2014] [Indexed: 10/25/2022]
Abstract
BACKGROUND To determine if metal artefact reduction (MAR) combined with a priori knowledge of prosthesis material composition can be applied to obtain CT-based attenuation maps with sufficient accuracy for quantitative assessment of (18)F-fluorodeoxyglucose uptake in lesions near metallic prostheses. METHODS A custom hip prosthesis phantom with a lesion-sized cavity filled with 0.2 ml (18)F-FDG solution having an activity of 3.367 MBq adjacent to a prosthesis bore was imaged twice with a chrome-cobalt steel hip prosthesis and a plastic replica, respectively. Scanning was performed on a clinical hybrid PET/CT system equipped with an additional external (137)Cs transmission source. PET emission images were reconstructed from both phantom configurations with CT-based attenuation correction (CTAC) and with CT-based attenuation correction using MAR (MARCTAC). To compare results with the attenuation-correction method extant prior to the advent of PET/CT, we also carried out attenuation correction with (137)Cs transmission-based attenuation correction (TXAC). CTAC and MARCTAC images were scaled to attenuation coefficients at 511 keV using a trilinear function that mapped the highest CT values to the prosthesis alloy attenuation coefficient. Accuracy and spatial distribution of the lesion activity was compared between the three reconstruction schemes. RESULTS Compared to the reference activity of 3.37 MBq, the estimated activity quantified from the PET image corrected by TXAC was 3.41 MBq. The activity estimated from PET images corrected by MARCTAC was similar in accuracy at 3.32 MBq. CTAC corrected PET images resulted in nearly 40 % overestimation of lesion activity at 4.70 MBq. Comparison of PET images obtained with the plastic and metal prostheses in place showed that CTAC resulted in a marked distortion of the (18)F-FDG distribution within the lesion, whereas application of MARCTAC and TXAC resulted in lesion distributions similar to those observed with the plastic replica. CONCLUSIONS MAR combined with a trilinear CT number mapping for PET attenuation correction resulted in estimates of lesion activity comparable in accuracy to that obtained with (137)Cs transmission-based attenuation correction, and far superior to estimates made without attenuation correction or with a standard CT attenuation map. The ability to use CT images for attenuation correction is a potentially important development because it obviates the need for a (137)Cs transmission source, which entails extra scan time, logistical complexity and expense.
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MR image based approach for metal artifact reduction in X-ray CT. ScientificWorldJournal 2013; 2013:524243. [PMID: 24302860 PMCID: PMC3834973 DOI: 10.1155/2013/524243] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2013] [Accepted: 09/25/2013] [Indexed: 01/01/2023] Open
Abstract
For decades, computed tomography (CT) images have been widely used to discover valuable anatomical information. Metallic implants such as dental fillings cause severe streaking artifacts which significantly degrade the quality of CT images. In this paper, we propose a new method for metal-artifact reduction using complementary magnetic resonance (MR) images. The method exploits the possibilities which arise from the use of emergent trimodality systems. The proposed algorithm corrects reconstructed CT images. The projected data which is affected by dental fillings is detected and the missing projections are replaced with data obtained from a corresponding MR image. A simulation study was conducted in order to compare the reconstructed images with images reconstructed through linear interpolation, which is a common metal-artifact reduction technique. The results show that the proposed method is successful in reducing severe metal artifacts without introducing significant amount of secondary artifacts.
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van der Bom IMJ, Hou SY, Puri AS, Spilberg G, Ruijters D, van de Haar P, Carelsen B, Vedantham S, Gounis MJ, Wakhloo AK. Reduction of coil mass artifacts in high-resolution flat detector conebeam CT of cerebral stent-assisted coiling. AJNR Am J Neuroradiol 2013; 34:2163-70. [PMID: 23721899 DOI: 10.3174/ajnr.a3561] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE Developments in flat panel angiographic C-arm systems have enabled visualization of both the neurovascular stents and host arteries in great detail, providing complementary spatial information in addition to conventional DSA. However, the visibility of these structures may be impeded by artifacts generated by adjacent radio-attenuating objects. We report on the use of a metal artifact reduction algorithm for high-resolution contrast-enhanced conebeam CT for follow-up imaging of stent-assisted coil embolization. MATERIALS AND METHODS Contrast-enhanced conebeam CT data were acquired in 25 patients who underwent stent-assisted coiling. Reconstructions were generated with and without metal artifact reduction and were reviewed by 3 experienced neuroradiologists by use of a 3-point scale. RESULTS With metal artifact reduction, the observers agreed that the visibility had improved by at least 1 point on the scoring scale in >40% of the cases (κ = 0.6) and that the streak artifact was not obscuring surrounding structures in 64% of all cases (κ = 0.6). Metal artifact reduction improved the image quality, which allowed for visibility sufficient for evaluation in 65% of the cases, and was preferred over no metal artifact reduction in 92% (κ = 0.9). Significantly higher scores were given with metal artifact reduction (P < .0001). CONCLUSIONS Although metal artifact reduction is not capable of fully removing artifacts caused by implants with high x-ray absorption, we have shown that the image quality of contrast-enhanced conebeam CT data are improved drastically. The impact of the artifacts on the visibility varied between cases, and yet the overall visibility of the contrast-enhanced conebeam CT with metal artifact reduction improved in most the cases.
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Affiliation(s)
- I M J van der Bom
- Department of Radiology, New England Center for Stroke Research, University of Massachusetts Medical School, Worcester, Massachusetts
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Lell MM, Meyer E, Schmid M, Raupach R, May MS, Uder M, Kachelriess M. Frequency split metal artefact reduction in pelvic computed tomography. Eur Radiol 2013; 23:2137-45. [PMID: 23519437 DOI: 10.1007/s00330-013-2809-y] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2012] [Revised: 01/16/2013] [Accepted: 02/02/2013] [Indexed: 10/27/2022]
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Delso G, Wollenweber S, Lonn A, Wiesinger F, Veit-Haibach P. MR-driven metal artifact reduction in PET/CT. Phys Med Biol 2013; 58:2267-80. [PMID: 23478566 DOI: 10.1088/0031-9155/58/7/2267] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Among the proposed system architectures capable of delivering positron emission tomography/magnetic resonance (PET/MR) datasets, tri-modality systems open an interesting field in which the synergies between these modalities can be exploited to address some of the problems encountered in standalone systems. In this paper we present a feasibility study of the correction of dental streak artifacts in computed tomography (CT)-based attenuation correction images using complementary MR data. The frequency and severity of metal artifacts in oncology patients was studied by inspecting the CT scans of 152 patients examined at our hospital. A prospective correction algorithm using CT and MR information to automatically locate and edit the region affected by metal artifacts was developed and tested retrospectively on data from 15 oncology patients referred for a PET/CT scan. In datasets without malignancies, the activity in Waldeyer's ring was used to measure the maximum uptake variation when the proposed correction was applied. The measured bias ranged from 10% to 30%. In datasets with malignancies on the slices affected by artifacts, the correction led to lesion uptake variations of 6.1% for a lesion 3 cm away from the implant, 1.5% for a lesion 7 cm away and <1% for a lesion 8 cm away.
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Affiliation(s)
- G Delso
- GE Healthcare, Waukesha, WI, USA.
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Abdoli M, Dierckx RAJO, Zaidi H. Metal artifact reduction strategies for improved attenuation correction in hybrid PET/CT imaging. Med Phys 2012; 39:3343-60. [DOI: 10.1118/1.4709599] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Abdoli M, de Jong JR, Pruim J, Dierckx RAJO, Zaidi H. Reduction of artefacts caused by hip implants in CT-based attenuation-corrected PET images using 2-D interpolation of a virtual sinogram on an irregular grid. Eur J Nucl Med Mol Imaging 2011; 38:2257-68. [PMID: 21850499 PMCID: PMC3218272 DOI: 10.1007/s00259-011-1900-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2011] [Accepted: 07/29/2011] [Indexed: 11/30/2022]
Abstract
Purpose Metallic prosthetic replacements, such as hip or knee implants, are known to cause strong streaking artefacts in CT images. These artefacts likely induce over- or underestimation of the activity concentration near the metallic implants when applying CT-based attenuation correction of positron emission tomography (PET) images. Since this degrades the diagnostic quality of the images, metal artefact reduction (MAR) prior to attenuation correction is required. Methods The proposed MAR method, referred to as virtual sinogram-based technique, replaces the projection bins of the sinogram that are influenced by metallic implants by a 2-D Clough-Tocher cubic interpolation scheme performed in an irregular grid, called Delaunay triangulated grid. To assess the performance of the proposed method, a physical phantom and 30 clinical PET/CT studies including hip prostheses were used. The results were compared to the method implemented on the Siemens Biograph mCT PET/CT scanner. Results Both phantom and clinical studies revealed that the proposed method performs equally well as the Siemens MAR method in the regions corresponding to bright streaking artefacts and the artefact-free regions. However, in regions corresponding to dark streaking artefacts, the Siemens method does not seem to appropriately correct the tracer uptake while the proposed method consistently increased the uptake in the underestimated regions, thus bringing it to the expected level. This observation is corroborated by the experimental phantom study which demonstrates that the proposed method approaches the true activity concentration more closely. Conclusion The proposed MAR method allows more accurate CT-based attenuation correction of PET images and prevents misinterpretation of tracer uptake, which might be biased owing to the propagation of bright and dark streaking artefacts from CT images to the PET data following the attenuation correction procedure.
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Affiliation(s)
- Mehrsima Abdoli
- Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, 9700 RB Groningen, The Netherlands
| | - Johan R. de Jong
- Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, 9700 RB Groningen, The Netherlands
| | - Jan Pruim
- Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, 9700 RB Groningen, The Netherlands
| | - Rudi A. J. O. Dierckx
- Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, 9700 RB Groningen, The Netherlands
| | - Habib Zaidi
- Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, 9700 RB Groningen, The Netherlands
- Division of Nuclear Medicine and Molecular Imaging, Geneva University Hospital, 1211 Geneva, Switzerland
- Geneva Neuroscience Center, Geneva University, 1205 Geneva, Switzerland
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Metal artifact reduction in cone beam computed tomography using forward projected reconstruction information. Z Med Phys 2011; 21:174-82. [PMID: 21530200 DOI: 10.1016/j.zemedi.2011.03.002] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2010] [Revised: 01/12/2011] [Accepted: 03/08/2011] [Indexed: 11/22/2022]
Abstract
In this work we present a new method to reduce artifacts, produced by high-density objects, especially metal implants, in X-ray cone beam computed tomography (CBCT). These artifacts influence clinical diagnostics and treatments using CT data, if metal objects are located in the field of view (FOV). Our novel method reduces metal artifacts by virtually replacing the metal objects with tissue objects of the same shape. First, the considered objects must be segmented in the original 2D projection data as well as in a reconstructed 3D volume. The attenuation coefficients of the segmented voxels are replaced with adequate attenuation coefficients of tissue (or water), then the required parts of the volume are projected onto the segmented 2D pixels, to replace the original information. This corrected 2D data can then be reconstructed with reduced artifacts, i. e. all metal objects virtually vanished. After the reconstruction, the segmented 3D metal objects were re-inserted into the corrected 3D volume. Our method was developed for mobile C-arm CBCTs; as it is necessary that they are of low weight, the C-arm results in unpredictable distortion. This misalignment between the original 2D data and the forward projection of the reconstructed 3D volume must be adjusted before the correction of the segmented 2D pixels. We applied this technique to clinical data and will now present the results.
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Abdoli M, Ay MR, Ahmadian A, Dierckx RAJO, Zaidi H. Reduction of dental filling metallic artifacts in CT-based attenuation correction of PET data using weighted virtual sinograms optimized by a genetic algorithm. Med Phys 2010; 37:6166-77. [PMID: 21302773 DOI: 10.1118/1.3511507] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Affiliation(s)
- Mehrsima Abdoli
- Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, 9700 RB Groningen, The Netherlands
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Is metal artefact reduction mandatory in cardiac PET/CT imaging in the presence of pacemaker and implantable cardioverter defibrillator leads? Eur J Nucl Med Mol Imaging 2010; 38:252-62. [DOI: 10.1007/s00259-010-1635-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2010] [Accepted: 09/28/2010] [Indexed: 11/26/2022]
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A virtual sinogram method to reduce dental metallic implant artefacts in computed tomography-based attenuation correction for PET. Nucl Med Commun 2010; 31:22-31. [PMID: 19829166 DOI: 10.1097/mnm.0b013e32832fa241] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Li TR, Tian JH, Wang H, Chen ZQ, Zhao CL. Pitfalls in Positron Emission Tomography/Computed Tomography Imaging: Causes and Their Classifications. ACTA ACUST UNITED AC 2009; 24:12-9. [DOI: 10.1016/s1001-9294(09)60052-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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