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Zhang X, Li H, Wang H, Liu X, Deng W, Zhong J, Fan L, Ling Q, Hu D, Qi H, Chen H. Iodine concentration, HU accuracy, and metal artifacts evaluation on second-generation dual-layer spectral detector CT images with metal implants: a phantom study. Acta Radiol 2024; 65:1030-1038. [PMID: 39140845 DOI: 10.1177/02841851241269853] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/15/2024]
Abstract
BACKGROUND Metal implants may affect the image quality, iodine concentration (IC), and CT Hounsfield unit (HU) quantification accuracy. PURPOSE To investigate the quantitative accuracy of IC and HU from dual-layer spectral detector (DLCT) in the presence of metal artifacts. MATERIAL AND METHODS An experimental cylindrical phantom containing eight iodine inserts and two metal inserts was designed. The phantom underwent scanning at three radiation dose levels and two tube voltage settings. A set of conventional images (CIs), virtual monoenergetic images (VMIs), and iodine concentration maps (ICMs) were generated and measured for all the eight iodine inserts. Quantitative indicators of mean absolute percentage error (MAPE), artifact index (AI), contrast-to-noise ratio (CNR), signal-to-noise ratio (SNR), and standard deviation (SD) on CIs and VMIs were calculated for IC and HU. Subjective score evaluation was also conducted. RESULTS The MAPEiodine values of all regions of interest across different scanning configurations were all <5%. Almost all APEiodine values were <5%, indicating that metal artifacts had little impact on IC measurements. When the tube voltage was fixed, the SD value of attenuation decreased with the increase of the tube current; this is also true when the tube current was fixed. The middle energy reconstructions seemed to give a good balance between reducing artifacts and improving contrast. CONCLUSION VMIs from DLCT can reduce metal artifacts, the accuracy of IC quantification is not sensitive to imaging parameters. In summary, metal implants exhibit minimal impact on image quality and IC quantification accuracy in reconstructed images from DLCT.
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Affiliation(s)
- Xinming Zhang
- Department of Clinical Engineering, Nanfang Hospital, Southern Medical University, Guangzhou, PR China
- School of Biomedical Engineering, Southern Medical University, Guangzhou, PR China
| | - Hanwei Li
- Department of Clinical Engineering, Nanfang Hospital, Southern Medical University, Guangzhou, PR China
| | - Haowen Wang
- Department of Clinical Engineering, Nanfang Hospital, Southern Medical University, Guangzhou, PR China
| | - Xiaomin Liu
- Clinical and Technical Support, Philips Healthcare, Shanghai, PR China
| | - Weiwei Deng
- Clinical and Technical Support, Philips Healthcare, Shanghai, PR China
| | - Jianqiu Zhong
- Clinical and Technical Support, Philips Healthcare, Shanghai, PR China
| | - Litian Fan
- Department of Clinical Engineering, Nanfang Hospital, Southern Medical University, Guangzhou, PR China
| | - Qingqing Ling
- Department of Clinical Engineering, Nanfang Hospital, Southern Medical University, Guangzhou, PR China
| | - Debin Hu
- Department of Clinical Engineering, Nanfang Hospital, Southern Medical University, Guangzhou, PR China
| | - Hongliang Qi
- Department of Clinical Engineering, Nanfang Hospital, Southern Medical University, Guangzhou, PR China
| | - Hongwen Chen
- Department of Clinical Engineering, Nanfang Hospital, Southern Medical University, Guangzhou, PR China
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Marth AA, Goller SS, Kajdi GW, Marcus RP, Sutter R. Photon-Counting Detector CT: Clinical Utility of Virtual Monoenergetic Imaging Combined With Tin Prefiltration to Reduce Metal Artifacts in the Postoperative Ankle. Invest Radiol 2024; 59:545-553. [PMID: 38214560 DOI: 10.1097/rli.0000000000001058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2024]
Abstract
OBJECTIVES The aim of this study was to compare the effectiveness and clinical utility of virtual monoenergetic image (VMI) reconstructions in computed tomography (CT) scans with and without tin prefiltration on a photon-counting detector (PCD) CT system to reduce metal implant artifacts in the postoperative ankle. MATERIALS AND METHODS This retrospective study included patients with internal fixation of the ankle scanned with and without tin prefiltration (Sn) on a PCD CT scanner between March and October 2023. Virtual monoenergetic images between 60 and 190 keV were reconstructed with a 10-keV increment in a bone kernel for both acquisitions (VMI Sn and VMI Std , respectively). Noise measurements assessed artifact reduction in the most prominent near-metal image distortions and were compared between acquisitions modes as well as between polychromatic images and VMIs. Three readers assessed the visibility of osseous healing along with interpretability and artifact extent for 5 reconstruction levels. RESULTS A total of 48 patients (21 females, 27 males; mean age, 55.1 ± 19.4 years) were included in this study. Tin-prefiltered acquisitions (n = 30) had a lower artifact level for polychromatic images and VMIs compared with non-tin-prefiltered acquisitions (n = 18; P ≤ 0.043). A significant reduction of metal artifacts was observed for VMI Sn ≥120 keV compared with polychromatic images (hyperdense artifacts: 40.2 HU [interquartile range (IQR) 39.8] vs 14.0 HU [IQR 11.1]; P ≤ 0.01 and hypodense artifacts: 91.2 HU [IQR 82.4] vs 29.7 HU [IQR 39.6]; P ≤ 0.001). For VMI Std , this applied to reconstructions ≥100 keV (hyperdense artifacts: 57.7 HU [IQR 33.4] vs 19.4 HU [IQR 27.6]; P ≤ 0.001 and hypodense artifacts: 106.9 HU [IQR 76.1] vs 57.4 HU [IQR 55.7]; P ≤ 0.021). For visibility of osseous healing, VMI Sn at 120 keV yielded higher ratings compared with polychromatic images ( P ≤ 0.001), whereas image interpretability was rated better ( P = 0.023), and artifact extent was rated lower ( P ≤ 0.001) compared with polychromatic images. CONCLUSIONS Tin-prefiltered VMI at 120 keV showed a significant reduction in metal artifacts compared with polychromatic images, whereas visibility of osseous healing and image interpretability was improved. Therefore, tin-prefiltration PCD CT with VMI reconstructions may be a helpful complement to postsurgical CT imaging of the ankle in patients with metal implants.
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Affiliation(s)
- Adrian A Marth
- From the Swiss Center for Musculoskeletal Imaging, Balgrist Campus AG, Zurich, Switzerland (A.A.M.); and Department of Radiology, Balgrist University Hospital, Faculty of Medicine, University of Zurich, Zurich, Switzerland (A.A.M., S.S.G., G.W.K., R.P.M., R.S.)
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Grunz JP, Huflage H. Photon-Counting Computed Tomography: Experience in Musculoskeletal Imaging. Korean J Radiol 2024; 25:662-672. [PMID: 38942460 PMCID: PMC11214923 DOI: 10.3348/kjr.2024.0096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2024] [Revised: 03/28/2024] [Accepted: 04/19/2024] [Indexed: 06/30/2024] Open
Abstract
Since the emergence of the first photon-counting computed tomography (PCCT) system in late 2021, its advantages and a wide range of applications in all fields of radiology have been demonstrated. Compared to standard energy-integrating detector-CT, PCCT allows for superior geometric dose efficiency in every examination. While this aspect by itself is groundbreaking, the advantages do not stop there. PCCT facilitates an unprecedented combination of ultra-high-resolution imaging without dose penalty or field-of-view restrictions, detector-based elimination of electronic noise, and ubiquitous multi-energy spectral information. Considering the high demands of orthopedic imaging for the visualization of minuscule details while simultaneously covering large portions of skeletal and soft tissue anatomy, no subspecialty may benefit more from this novel detector technology than musculoskeletal radiology. Deeply rooted in experimental and clinical research, this review article aims to provide an introduction to the cosmos of PCCT, explain its technical basics, and highlight the most promising applications for patient care, while also mentioning current limitations that need to be overcome.
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Affiliation(s)
- Jan-Peter Grunz
- Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Würzburg, Germany.
| | - Henner Huflage
- Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Würzburg, Germany
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Goller SS, Sutter R. Advanced Imaging of Total Knee Arthroplasty. Semin Musculoskelet Radiol 2024; 28:282-292. [PMID: 38768593 DOI: 10.1055/s-0044-1781470] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
The prevalence of total knee arthroplasty (TKA) is increasing with the aging population. Although long-term results are satisfactory, suspected postoperative complications often require imaging with the implant in place. Advancements in computed tomography (CT), such as tin prefiltration, metal artifact reduction algorithms, dual-energy CT with virtual monoenergetic imaging postprocessing, and the application of cone-beam CT and photon-counting detector CT, allow a better depiction of the tissues adjacent to the metal. For magnetic resonance imaging (MRI), high bandwidth (BW) optimization, the combination of view angle tilting and high BW, as well as multispectral imaging techniques with multiacquisition variable-resonance image combination or slice encoding metal artifact correction, have significantly improved imaging around metal implants, turning MRI into a useful clinical tool for patients with suspected TKA complications.
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Affiliation(s)
- Sophia Samira Goller
- Department of Radiology, Balgrist University Hospital, Faculty of Medicine, University of Zurich, Zurich, Switzerland
| | - Reto Sutter
- Department of Radiology, Balgrist University Hospital, Faculty of Medicine, University of Zurich, Zurich, Switzerland
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Haag F, Hokamp NG, Overhoff D, Dasegowda G, Kuru M, Nörenberg D, Schoenberg SO, Kalra MK, Froelich MF. Potential of photon counting computed tomography derived spectral reconstructions to reduce beam-hardening artifacts in chest CT. Eur J Radiol 2024; 175:111448. [PMID: 38574510 DOI: 10.1016/j.ejrad.2024.111448] [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: 08/04/2023] [Revised: 02/02/2024] [Accepted: 03/25/2024] [Indexed: 04/06/2024]
Abstract
PURPOSE Aim of the recent study is to point out a method to optimize quality of CT scans in oncological patients with port systems. This study investigates the potential of photon counting computed tomography (PCCT) for reduction of beam hardening artifacts caused by port-implants in chest imaging by means of spectral reconstructions. METHOD In this retrospective single-center study, 8 ROIs for 19 spectral reconstructions (polyenergetic imaging, monoenergetic reconstructions from 40 to 190 keV as well as iodine maps and virtual non contrast (VNC)) of 49 patients with pectoral port systems undergoing PCCT of the chest for staging of oncologic disease were measured. Mean values and standard deviation (SD) Hounsfield unit measurements of port-chamber associated hypo- and hyperdense artifacts, bilateral muscles and vessels has been carried out. Also, a structured assessment of artifacts and imaging findings was performed by two radiologists. RESULTS A significant association of keV with iodine contrast as well as artifact intensity was noted (all p < 0.001). In qualitative assessment, utilization of 120 keV monoenergetic reconstructions could reduce severe and pronounced artifacts completely, as compared to lower keV reconstructions (p < 0.001). Regarding imaging findings, no significant difference between monoenergetic reconstructions was noted (all p > 0.05). In cases with very high iodine concentrations in the subclavian vein, image distortions were noted at 40 keV images (p < 0.01). CONCLUSIONS The present study demonstrates that PCCT derived spectral reconstructions can be used in oncological imaging of the thorax to reduce port-derived beam-hardening artefacts. When evaluating image data sets within a staging, it can be particularly helpful to consider the 120 keV VMIs, in which the artefacts are comparatively low.
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Affiliation(s)
- Florian Haag
- Department of Radiology and Nuclear Medicine, University Medical Center Mannheim, Heidelberg University, Theodor-Kutzer-Ufer 1-3, 68167 Mannheim, Germany
| | - Nils Große Hokamp
- Institute for Diagnostic and Interventional Radiology, Faculty of Medicine and University Hospital Cologne, University of Cologne, Germany
| | - Daniel Overhoff
- Department of Radiology and Nuclear Medicine, University Medical Center Mannheim, Heidelberg University, Theodor-Kutzer-Ufer 1-3, 68167 Mannheim, Germany; Bundeswehrzentralkrankenhaus, Koblenz, Germany
| | - Giridhar Dasegowda
- Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Mustafa Kuru
- Department of Radiology and Nuclear Medicine, University Medical Center Mannheim, Heidelberg University, Theodor-Kutzer-Ufer 1-3, 68167 Mannheim, Germany
| | - Dominik Nörenberg
- Department of Radiology and Nuclear Medicine, University Medical Center Mannheim, Heidelberg University, Theodor-Kutzer-Ufer 1-3, 68167 Mannheim, Germany
| | - Stefan O Schoenberg
- Department of Radiology and Nuclear Medicine, University Medical Center Mannheim, Heidelberg University, Theodor-Kutzer-Ufer 1-3, 68167 Mannheim, Germany
| | - Mannudeep K Kalra
- Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Matthias F Froelich
- Department of Radiology and Nuclear Medicine, University Medical Center Mannheim, Heidelberg University, Theodor-Kutzer-Ufer 1-3, 68167 Mannheim, Germany; Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
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Ge S, Kumar N, Hallinan JTPD. Pedicle Screw Pseudofracture on Computed Tomography Secondary to Metal Artifact Reduction. Diagnostics (Basel) 2024; 14:108. [PMID: 38201417 PMCID: PMC10795680 DOI: 10.3390/diagnostics14010108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Revised: 12/20/2023] [Accepted: 12/28/2023] [Indexed: 01/12/2024] Open
Abstract
Metal artifact reduction (MAR) algorithms are commonly used in computed tomography (CT) scans where metal implants are involved. However, MAR algorithms also have the potential to create new artifacts in reconstructed images. We present a case of a screw pseudofracture due to MAR on CT.
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Affiliation(s)
- Shuliang Ge
- Department of Diagnostic Imaging, National University Hospital, 5 Lower Kent Ridge Road, Singapore 119074, Singapore
| | - Naresh Kumar
- University Spine Centre, Department of Orthopaedic Surgery, National University Health System, 1E, Lower Kent Ridge Road, Singapore 119228, Singapore
| | - James Thomas Patrick Decourcy Hallinan
- Department of Diagnostic Imaging, National University Hospital, 5 Lower Kent Ridge Road, Singapore 119074, Singapore
- Department of Diagnostic Radiology, Yong Loo Lin School of Medicine, National University of Singapore, 10 Medical Drive, Singapore 117597, Singapore
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Patzer TS, Grunz JP, Huflage H, Hennes JL, Pannenbecker P, Gruschwitz P, Afat S, Herrmann J, Bley TA, Kunz AS. Ultra-high resolution photon-counting CT with tin prefiltration for bone-metal interface visualization. Eur J Radiol 2024; 170:111209. [PMID: 37992609 DOI: 10.1016/j.ejrad.2023.111209] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Revised: 11/08/2023] [Accepted: 11/16/2023] [Indexed: 11/24/2023]
Abstract
PURPOSE To investigate the metal artifact suppression potential of combining tin prefiltration and virtual monoenergetic imaging (VMI) for osseous microarchitecture depiction in ultra-high-resolution (UHR) photon-counting CT (PCCT) of the lower extremity. METHOD Derived from tin-filtered UHR scans at 140 kVp, polychromatic datasets (T3D) and VMI reconstructions at 70, 110, 150, and 190 keV were compared in 117 patients with lower extremity metal implants (53 female; 62.1 ± 18.0 years). Three implant groups were investigated (total arthroplasty [n = 48], osteosynthetic material [n = 43], and external fixation [n = 26]). Image quality was assessed with regions of interest placed in the most pronounced artifacts and adjacent soft tissue, measuring the respective attenuation. Additionally, artifact extent, bone-metal interface interpretability and overall image quality were independently evaluated by three radiologists. RESULTS Artifact reduction was superior with increasing keV level of VMI. While T3D was superior to VMI70keV (p ≥ 0.117), artifacts were more severe in T3D than in VMI ≥ 110 keV (all p ≤ 0.036). Image noise was highest for VMI70keV (all p < 0.001) and lowest for VMI110keV with comparable results for VMI110keV - VMI190keV. Subjective image quality regarding artifacts was superior for VMI ≥ 110 keV (all p ≤ 0.042) and comparable for VMI110keV - VMI190keV. Bone-metal interface interpretability was superior for VMI110keV (all p ≤ 0.001), while T3D, VMI150keV and VMI190keV were comparable. Overall image quality was deemed best for VMI110keV and VMI150keV. Interreader reliability was good in all cases (ICC ≥ 0.833). CONCLUSIONS Tin-filtered UHR-PCCT scans of the lower extremity combined with VMI reconstructions allow for efficient artifact reduction in the vicinity of bone-metal interfaces.
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Affiliation(s)
- Theresa Sophie Patzer
- Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Oberdürrbacher Straße 6, 97080 Würzburg, Germany.
| | - Jan-Peter Grunz
- Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Oberdürrbacher Straße 6, 97080 Würzburg, Germany
| | - Henner Huflage
- Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Oberdürrbacher Straße 6, 97080 Würzburg, Germany
| | - Jan-Lucca Hennes
- Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Oberdürrbacher Straße 6, 97080 Würzburg, Germany
| | - Pauline Pannenbecker
- Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Oberdürrbacher Straße 6, 97080 Würzburg, Germany
| | - Philipp Gruschwitz
- Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Oberdürrbacher Straße 6, 97080 Würzburg, Germany
| | - Saif Afat
- Department of Diagnostic and Interventional Radiology, University Hospital Tübingen, Hoppe-Seyler-Str 3, 72076 Tübingen, Germany
| | - Judith Herrmann
- Department of Diagnostic and Interventional Radiology, University Hospital Tübingen, Hoppe-Seyler-Str 3, 72076 Tübingen, Germany
| | - Thorsten Alexander Bley
- Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Oberdürrbacher Straße 6, 97080 Würzburg, Germany
| | - Andreas Steven Kunz
- Department of Diagnostic and Interventional Radiology, University Hospital Tübingen, Hoppe-Seyler-Str 3, 72076 Tübingen, Germany
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Selles M, van Osch JAC, Maas M, Boomsma MF, Wellenberg RHH. Advances in metal artifact reduction in CT images: A review of traditional and novel metal artifact reduction techniques. Eur J Radiol 2024; 170:111276. [PMID: 38142571 DOI: 10.1016/j.ejrad.2023.111276] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Revised: 12/14/2023] [Accepted: 12/18/2023] [Indexed: 12/26/2023]
Abstract
Metal artifacts degrade CT image quality, hampering clinical assessment. Numerous metal artifact reduction methods are available to improve the image quality of CT images with metal implants. In this review, an overview of traditional methods is provided including the modification of acquisition and reconstruction parameters, projection-based metal artifact reduction techniques (MAR), dual energy CT (DECT) and the combination of these techniques. Furthermore, the additional value and challenges of novel metal artifact reduction techniques that have been introduced over the past years are discussed such as photon counting CT (PCCT) and deep learning based metal artifact reduction techniques.
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Affiliation(s)
- Mark Selles
- Department of Radiology, Isala, 8025 AB Zwolle, the Netherlands; Department of Radiology and Nuclear Medicine, Amsterdam University Medical Centre, 1105 AZ Amsterdam, the Netherlands; Amsterdam Movement Sciences, 1081 BT Amsterdam, the Netherlands.
| | | | - Mario Maas
- Department of Radiology and Nuclear Medicine, Amsterdam University Medical Centre, 1105 AZ Amsterdam, the Netherlands; Amsterdam Movement Sciences, 1081 BT Amsterdam, the Netherlands
| | | | - Ruud H H Wellenberg
- Department of Radiology and Nuclear Medicine, Amsterdam University Medical Centre, 1105 AZ Amsterdam, the Netherlands; Amsterdam Movement Sciences, 1081 BT Amsterdam, the Netherlands
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Schreck J, Laukamp KR, Niehoff JH, Michael AE, Boriesosdick J, Wöltjen MM, Kröger JR, Reimer RP, Grunz JP, Borggrefe J, Lennartz S. Metal artifact reduction in patients with total hip replacements: evaluation of clinical photon counting CT using virtual monoenergetic images. Eur Radiol 2023; 33:9286-9295. [PMID: 37436505 PMCID: PMC10667386 DOI: 10.1007/s00330-023-09879-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Revised: 04/25/2023] [Accepted: 04/27/2023] [Indexed: 07/13/2023]
Abstract
OBJECTIVES To investigate photon-counting CT (PCCT)-derived virtual monoenergetic images (VMI) for artifact reduction in patients with unilateral total hip replacements (THR). METHODS Forty-two patients with THR and portal-venous phase PCCT of the abdomen and pelvis were retrospectively included. For the quantitative analysis, region of interest (ROI)-based measurements of hypodense and hyperdense artifacts, as well as of artifact-impaired bone and the urinary bladder, were conducted, and corrected attenuation and image noise were calculated as the difference of attenuation and noise between artifact-impaired and normal tissue. Two radiologists qualitatively evaluated artifact extent, bone assessment, organ assessment, and iliac vessel assessment using 5-point Likert scales. RESULTS VMI110keV yielded a significant reduction of hypo- and hyperdense artifacts compared to conventional polyenergetic images (CI) and the corrected attenuation closest to 0, indicating best possible artifact reduction (hypodense artifacts: CI: 237.8 ± 71.4 HU, VMI110keV: 8.5 ± 122.5 HU; p < 0.05; hyperdense artifacts: CI: 240.6 ± 40.8 HU vs. VMI110keV: 13.0 ± 110.4 HU; p < 0.05). VMI110keV concordantly provided best artifact reduction in the bone and bladder as well as the lowest corrected image noise. In the qualitative assessment, VMI110keV received the best ratings for artifact extent (CI: 2 (1-3), VMI110keV: 3 (2-4); p < 0.05) and bone assessment (CI: 3 (1-4), VMI110keV: 4 (2-5); p < 0.05), whereas organ and iliac vessel assessments were rated highest in CI and VMI70keV. CONCLUSIONS PCCT-derived VMI effectively reduce artifacts from THR and thereby improve assessability of circumjacent bone tissue. VMI110keV yielded optimal artifact reduction without overcorrection, yet organ and vessel assessments at that energy level and higher were impaired by loss of contrast. CLINICAL RELEVANCE STATEMENT PCCT-enabled artifact reduction is a feasible method for improving assessability of the pelvis in patients with total hip replacements at clinical routine imaging. KEY POINTS • Photon-counting CT-derived virtual monoenergetic images at 110 keV yielded best reduction of hyper- and hypodense artifacts, whereas higher energy levels resulted in artifact overcorrection. • The qualitative artifact extent was reduced best in virtual monoenergetic images at 110 keV, facilitating an improved assessment of the circumjacent bone. • Despite significant artifact reduction, assessment of pelvic organs as well as vessels did not profit from energy levels higher than 70 keV, due to the decline in image contrast.
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Affiliation(s)
- Julian Schreck
- Department of Radiology, Neuroradiology and Nuclear Medicine, Johannes Wesling University Hospital, Ruhr University Bochum, 44801, Bochum, Germany
| | - Kai Roman Laukamp
- Institute for Diagnostic and Interventional Radiology, Faculty of Medicine and University Hospital Cologne, University of Cologne, 50937, Cologne, Germany
| | - Julius Henning Niehoff
- Department of Radiology, Neuroradiology and Nuclear Medicine, Johannes Wesling University Hospital, Ruhr University Bochum, 44801, Bochum, Germany
| | - Arwed Elias Michael
- Department of Radiology, Neuroradiology and Nuclear Medicine, Johannes Wesling University Hospital, Ruhr University Bochum, 44801, Bochum, Germany
| | - Jan Boriesosdick
- Department of Radiology, Neuroradiology and Nuclear Medicine, Johannes Wesling University Hospital, Ruhr University Bochum, 44801, Bochum, Germany
| | - Matthias Michael Wöltjen
- Department of Radiology, Neuroradiology and Nuclear Medicine, Johannes Wesling University Hospital, Ruhr University Bochum, 44801, Bochum, Germany
| | - Jan Robert Kröger
- Department of Radiology, Neuroradiology and Nuclear Medicine, Johannes Wesling University Hospital, Ruhr University Bochum, 44801, Bochum, Germany
| | - Robert P Reimer
- Institute for Diagnostic and Interventional Radiology, Faculty of Medicine and University Hospital Cologne, University of Cologne, 50937, Cologne, Germany
| | - Jan-Peter Grunz
- Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Oberdürrbacher Straße 6, 97080, Würzburg, Germany
| | - Jan Borggrefe
- Department of Radiology, Neuroradiology and Nuclear Medicine, Johannes Wesling University Hospital, Ruhr University Bochum, 44801, Bochum, Germany
| | - Simon Lennartz
- Institute for Diagnostic and Interventional Radiology, Faculty of Medicine and University Hospital Cologne, University of Cologne, 50937, Cologne, Germany.
- Institute for Diagnostic and Interventional Radiology, University Hospital Cologne, Kerpener Straße 62, 50937, Cologne, Germany.
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Guo R, Zou Y, Zhang S, An J, Zhang G, Du X, Gong H, Xiong S, Long Y, Ma J. Preclinical validation of a novel deep learning-based metal artifact correction algorithm for orthopedic CT imaging. J Appl Clin Med Phys 2023; 24:e14166. [PMID: 37787513 PMCID: PMC10647951 DOI: 10.1002/acm2.14166] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Revised: 06/25/2023] [Accepted: 09/05/2023] [Indexed: 10/04/2023] Open
Abstract
PURPOSE To validate a novel deep learning-based metal artifact correction (MAC) algorithm for CT, namely, AI-MAC, in preclinical setting with comparison to conventional MAC and virtual monochromatic imaging (VMI) technique. MATERIALS AND METHODS An experimental phantom was designed by consecutively inserting two sets of pedicle screws (size Φ 6.5 × 30-mm and Φ 7.5 × 40-mm) into a vertebral specimen to simulate the clinical scenario of metal implantation. The resulting MAC, VMI, and AI-MAC images were compared with respect to the metal-free reference image by subjective scoring, as well as by CT attenuation, image noise, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and correction accuracy via adaptive segmentation of the paraspinal muscle and vertebral body. RESULTS The AI-MAC and VMI images showed significantly higher subjective scores than the MAC image (all p < 0.05). The SNRs and CNRs on the AI-MAC image were comparable to the reference (all p > 0.05), whereas those on the VMI were significantly lower (all p < 0.05). The paraspinal muscle segmented on the AI-MAC image was 4.6% and 5.1% more complete to the VMI and MAC images for the Φ 6.5 × 30-mm screws, and 5.0% and 5.1% for the Φ 7.5 × 40-mm screws, respectively. The vertebral body segmented on the VMI was closest to the reference, with only 3.2% and 7.4% overestimation for Φ 6.5 × 30-mm and Φ 7.5 × 40-mm screws, respectively. CONCLUSIONS Using metal-free reference as the ground truth for comparison, the AI-MAC outperforms VMI in characterizing soft tissue, while VMI is useful in skeletal depiction.
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Affiliation(s)
- Rui Guo
- Department of RadiologyXinjiang Production & Construction Corps HospitalUrumqiChina
| | | | - Shuai Zhang
- Department of RadiologyXinjiang Production & Construction Corps HospitalUrumqiChina
| | - Jiajia An
- Department of RadiologyXinjiang Production & Construction Corps HospitalUrumqiChina
| | | | - Xiangdong Du
- Department of RadiologyXinjiang Production & Construction Corps HospitalUrumqiChina
| | - Huan Gong
- Department of RadiologyXinjiang Production & Construction Corps HospitalUrumqiChina
| | - Sining Xiong
- Department of RadiologyXinjiang Production & Construction Corps HospitalUrumqiChina
| | - Yangfei Long
- Department of RadiologyXinjiang Production & Construction Corps HospitalUrumqiChina
| | - Jing Ma
- Department of RadiologyXinjiang Production & Construction Corps HospitalUrumqiChina
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Patzer TS, Kunz AS, Huflage H, Gruschwitz P, Pannenbecker P, Afat S, Herrmann J, Petritsch B, Bley TA, Grunz JP. Combining virtual monoenergetic imaging and iterative metal artifact reduction in first-generation photon-counting computed tomography of patients with dental implants. Eur Radiol 2023; 33:7818-7829. [PMID: 37284870 PMCID: PMC10598126 DOI: 10.1007/s00330-023-09790-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Revised: 04/04/2023] [Accepted: 04/27/2023] [Indexed: 06/08/2023]
Abstract
OBJECTIVES While established for energy-integrating detector computed tomography (CT), the effect of virtual monoenergetic imaging (VMI) and iterative metal artifact reduction (iMAR) in photon-counting detector (PCD) CT lacks thorough investigation. This study evaluates VMI, iMAR, and combinations thereof in PCD-CT of patients with dental implants. MATERIAL AND METHODS In 50 patients (25 women; mean age 62.0 ± 9.9 years), polychromatic 120 kVp imaging (T3D), VMI, T3DiMAR, and VMIiMAR were compared. VMIs were reconstructed at 40, 70, 110, 150, and 190 keV. Artifact reduction was assessed by attenuation and noise measurements in the most hyper- and hypodense artifacts, as well as in artifact-impaired soft tissue of the mouth floor. Three readers subjectively evaluated artifact extent and soft tissue interpretability. Furthermore, new artifacts through overcorrection were assessed. RESULTS iMAR reduced hyper-/hypodense artifacts (T3D 1305.0/-1418.4 versus T3DiMAR 103.2/-46.9 HU), soft tissue impairment (106.7 versus 39.7 HU), and image noise (16.9 versus 5.2 HU) compared to non-iMAR datasets (p ≤ 0.001). VMIiMAR ≥ 110 keV subjectively enhanced artifact reduction over T3DiMAR (p ≤ 0.023). Without iMAR, VMI displayed no measurable artifact reduction (p ≥ 0.186) and facilitated no significant denoising over T3D (p ≥ 0.366). However, VMI ≥ 110 keV reduced soft tissue impairment (p ≤ 0.009). VMIiMAR ≥ 110 keV resulted in less overcorrection than T3DiMAR (p ≤ 0.001). Inter-reader reliability was moderate/good for hyperdense (0.707), hypodense (0.802), and soft tissue artifacts (0.804). CONCLUSION While VMI alone holds minimal metal artifact reduction potential, iMAR post-processing enabled substantial reduction of hyperdense and hypodense artifacts. The combination of VMI ≥ 110 keV and iMAR resulted in the least extensive metal artifacts. CLINICAL RELEVANCE Combining iMAR with VMI represents a potent tool for maxillofacial PCD-CT with dental implants achieving substantial artifact reduction and high image quality. KEY POINTS • Post-processing of photon-counting CT scans with an iterative metal artifact reduction algorithm substantially reduces hyperdense and hypodense artifacts arising from dental implants. • Virtual monoenergetic images presented only minimal metal artifact reduction potential. • The combination of both provided a considerable benefit in subjective analysis compared to iterative metal artifact reduction alone.
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Affiliation(s)
- Theresa Sophie Patzer
- Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Oberdürrbacherstraße 6, 97080, Würzburg, Germany.
| | - Andreas Steven Kunz
- Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Oberdürrbacherstraße 6, 97080, Würzburg, Germany
| | - Henner Huflage
- Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Oberdürrbacherstraße 6, 97080, Würzburg, Germany
| | - Philipp Gruschwitz
- Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Oberdürrbacherstraße 6, 97080, Würzburg, Germany
| | - Pauline Pannenbecker
- Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Oberdürrbacherstraße 6, 97080, Würzburg, Germany
| | - Saif Afat
- Department of Diagnostic and Interventional Radiology, University Hospital Tübingen, Hoppe-Seyler-Str 3, 72076, Tübingen, Germany
| | - Judith Herrmann
- Department of Diagnostic and Interventional Radiology, University Hospital Tübingen, Hoppe-Seyler-Str 3, 72076, Tübingen, Germany
| | - Bernhard Petritsch
- Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Oberdürrbacherstraße 6, 97080, Würzburg, Germany
| | - Thorsten Alexander Bley
- Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Oberdürrbacherstraße 6, 97080, Würzburg, Germany
| | - Jan-Peter Grunz
- Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Oberdürrbacherstraße 6, 97080, Würzburg, Germany
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Zhao J, Cheng Q, Liu C, Wang Q, Lv Y, Tang Z, Luo Y, Yang H. Optimal combination periprosthetic vasculature visualization and metal artifact reduction by spectral computed tomography using virtual monoenergetic images in total hip arthroplasty. Insights Imaging 2023; 14:181. [PMID: 37880460 PMCID: PMC10600072 DOI: 10.1186/s13244-023-01533-3] [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: 07/23/2023] [Accepted: 09/29/2023] [Indexed: 10/27/2023] Open
Abstract
OBJECTIVES To investigate the optimal parameters of spectral CT for preferably visualizing the periprosthetic vasculature and metal artifact reduction (MAR) in total hip arthroplasty (THA). METHODS A total of 34 THA of 30 patients were retrospectively included. Image reconstructions included conventional image (CI), CI combined with MAR (CIMAR), and virtual monoenergetic images (VMI) combined with MAR (VMIMAR) at 50-120 keV. The attenuation and standard deviation of the vessel and artifact, and the width of artifact were measured. Qualitative scoring was evaluated including the vascular contour, the extent of artifact, and overall diagnostic evaluation. RESULTS The attenuation, noise of the vessel and artifact, and the width of artifact decreased as the energy level increased (p < 0.001). The downtrend was relatively flat at 80-120 keV, and the vascular attenuation dropped to 200 HU at 90 keV. The qualitative rating of vascular contour was significantly higher at CIMAR (3.47) and VMIMAR 60-80 keV (2.82-3.65) compared with CI (2.03) (p ≤ 0.029), and the highest score occurred at 70 and 80 keV (3.65 and 3.56). The score of the extent of artifact was higher at VMIMAR 80 keV than CIMAR (3.53 VS 3.12, p = 0.003). The score of the overall diagnostic evaluation was higher at VMIMAR 70 and 80 keV (3.32 and 3.53, respectively) than CIMAR (3.12) (p ≤ 0.035). CONCLUSION Eighty kiloelectron volts on VMIMAR, providing satisfactorily reduced metal artifacts and improved vascular visualization, can be an optimal recommended parameter of spectrum CT for the assessment of periprosthetic vasculature in THA patients. CRITICAL RELEVANCE STATEMENT The metal artifact is gradually reducing with increasing energy level; however, the vascular visualization is worsening. The vascular visualization is terrible above 100 keV, while the vessel is disturbed by artifacts below 70 keV. The best performance is found at 80 keV. KEY POINTS • VMIMAR can provide both reduced metal artifacts and improved vascular visualization. • Eighty kiloelectron volts on VMIMAR performs best in vascular visualization of total hip arthroplasty patients. • Energy spectrum CT is recommended for routine use in patients with total hip arthroplasty.
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Affiliation(s)
- Jie Zhao
- Department of Radiology, The First Affiliated Hospital of Chongqing Medical University, 1 Youyi Road, Yuzhong District, Chongqing, 400016, China
| | - Qiang Cheng
- Department of Orthopedics, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Chuan Liu
- Department of Radiology, The First Affiliated Hospital of Chongqing Medical University, 1 Youyi Road, Yuzhong District, Chongqing, 400016, China
| | - Qiqi Wang
- Department of Radiology, The First Affiliated Hospital of Chongqing Medical University, 1 Youyi Road, Yuzhong District, Chongqing, 400016, China
| | - Yuchan Lv
- Department of Radiology, The First Affiliated Hospital of Chongqing Medical University, 1 Youyi Road, Yuzhong District, Chongqing, 400016, China
| | - Ziyi Tang
- Department of Radiology, The First Affiliated Hospital of Chongqing Medical University, 1 Youyi Road, Yuzhong District, Chongqing, 400016, China
| | - Yuxi Luo
- Department of Radiology, The First Affiliated Hospital of Chongqing Medical University, 1 Youyi Road, Yuzhong District, Chongqing, 400016, China
| | - Haitao Yang
- Department of Radiology, The First Affiliated Hospital of Chongqing Medical University, 1 Youyi Road, Yuzhong District, Chongqing, 400016, China.
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Popp D, Sinzinger AX, Decker JA, Braun F, Bette S, Risch F, Haerting M, Garthe T, Scheurig-Muenkler C, Kroencke TJ, Schwarz F. Spectral metal artifact reduction after posterior spinal fixation in photon-counting detector CT datasets. Eur J Radiol 2023; 165:110946. [PMID: 37399668 DOI: 10.1016/j.ejrad.2023.110946] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Revised: 06/12/2023] [Accepted: 06/19/2023] [Indexed: 07/05/2023]
Abstract
PURPOSE To investigate the usefulness of virtual monoenergetic image (VMI) reconstructions derived from scans on a novel photon-counting detector CT (PCD-CT) for artifact reduction in patients after posterior spinal fixation. METHODS This retrospective cohort study included 23 patients status post posterior spinal fixation. Subjects were scanned on a novel PCD-CT (NAEOTOM Alpha, Siemens Healthineers, Erlangen, Germany) as part of routine clinical care. 14 sets of VMI reconstructions were derived in 10 keV increments for the interval 60-190 keV. The mean and the standard deviation (SD) of CT-values in 12 defined locations around a pair of pedicle screws on one vertebral level and the SD of homogenous fat were measured and used to calculate an artifact index (AIx). RESULTS Averaged over all regions, the lowest AIx was observed at VMI levels of 110 keV (32.5 (27.8-37.9)) which was significantly different from those of VMIs ≤ 90 keV (p < 0.001) or ≥160 keV (p < 0.015), respectively. Overall AIx values increased in both lower- and higher-keV levels. Regarding individual locations, either a monotonous AIx-decrease for increasing keV values or an AIx-minimum in intermediate-keV levels (100-140 keV) was found. In locations adjacent to larger metal parts, the increase of AIx values at the high-end of the keV spectrum was mainly explained by a reappearance of streak artifacts. CONCLUSION Our findings suggest that 110 keV is the optimal VMI setting for overall artifact suppression. In specific anatomical regions, however, slight adjustments towards higher-keV levels may provide better results.
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Affiliation(s)
- Daniel Popp
- Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Augsburg, Stenglinstr. 2, 86156 Augsburg, Germany.
| | - Andrea X Sinzinger
- Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Augsburg, Stenglinstr. 2, 86156 Augsburg, Germany.
| | - Josua A Decker
- Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Augsburg, Stenglinstr. 2, 86156 Augsburg, Germany.
| | - Franziska Braun
- Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Augsburg, Stenglinstr. 2, 86156 Augsburg, Germany.
| | - Stefanie Bette
- Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Augsburg, Stenglinstr. 2, 86156 Augsburg, Germany.
| | - Franka Risch
- Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Augsburg, Stenglinstr. 2, 86156 Augsburg, Germany.
| | - Mark Haerting
- Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Augsburg, Stenglinstr. 2, 86156 Augsburg, Germany.
| | - Tarik Garthe
- Department of Trauma, Orthopedics, Plastic and Hand Surgery, University Hospital Augsburg, Stenglinstr. 2, 86156 Augsburg, Germany.
| | - Christian Scheurig-Muenkler
- Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Augsburg, Stenglinstr. 2, 86156 Augsburg, Germany.
| | - Thomas J Kroencke
- Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Augsburg, Stenglinstr. 2, 86156 Augsburg, Germany.
| | - Florian Schwarz
- Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Augsburg, Stenglinstr. 2, 86156 Augsburg, Germany; Institute for Radiology, DONAUISAR Hospital Deggendorf-Dingolfing-Landau, Perlasberger Str. 41, 94469 Deggendorf, Germany; Medical Faculty, Ludwig Maximilian University Munich, Bavariaring 19, 80336 Munich, Germany.
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Rau A, Straehle J, Stein T, Diallo T, Rau S, Faby S, Nikolaou K, Schoenberg SO, Overhoff D, Beck J, Urbach H, Klingler JH, Bamberg F, Weiss J. Photon-Counting Computed Tomography (PC-CT) of the spine: impact on diagnostic confidence and radiation dose. Eur Radiol 2023; 33:5578-5586. [PMID: 36890304 PMCID: PMC10326119 DOI: 10.1007/s00330-023-09511-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Revised: 01/23/2023] [Accepted: 02/10/2023] [Indexed: 03/10/2023]
Abstract
OBJECTIVES Computed tomography (CT) is employed to evaluate surgical outcome after spinal interventions. Here, we investigate the potential of multispectral photon-counting computed tomography (PC-CT) on image quality, diagnostic confidence, and radiation dose compared to an energy-integrating CT (EID-CT). METHODS In this prospective study, 32 patients underwent PC-CT of the spine. Data was reconstructed in two ways: (1) standard bone kernel with 65-keV (PC-CTstd) and (2) 130-keV monoenergetic images (PC-CT130 keV). Prior EID-CT was available for 17 patients; for the remaining 15, an age-, sex-, and body mass index-matched EID-CT cohort was identified. Image quality (5-point Likert scales on overall, sharpness, artifacts, noise, diagnostic confidence) of PC-CTstd and EID-CT was assessed by four radiologists independently. If metallic implants were present (n = 10), PC-CTstd and PC-CT130 keV images were again assessed by 5-point Likert scales by the same radiologists. Hounsfield units (HU) were measured within metallic artifact and compared between PC-CTstd and PC-CT130 keV. Finally, the radiation dose (CTDIvol) was evaluated. RESULTS Sharpness was rated significantly higher (p = 0.009) and noise significantly lower (p < 0.001) in PC-CTstd vs. EID-CT. In the subset of patients with metallic implants, reading scores for PC-CT130 keV revealed superior ratings vs. PC-CTstd for image quality, artifacts, noise, and diagnostic confidence (all p < 0.001) accompanied by a significant increase of HU values within the artifact (p < 0.001). Radiation dose was significantly lower for PC-CT vs. EID-CT (mean CTDIvol: 8.83 vs. 15.7 mGy; p < 0.001). CONCLUSIONS PC-CT of the spine with high-kiloelectronvolt reconstructions provides sharper images, higher diagnostic confidence, and lower radiation dose in patients with metallic implants. KEY POINTS • Compared to energy-integrating CT, photon-counting CT of the spine had significantly higher sharpness and lower image noise while radiation dose was reduced by 45%. • In patients with metallic implants, virtual monochromatic photon-counting images at 130 keV were superior to standard reconstruction at 65 keV in terms of image quality, artifacts, noise, and diagnostic confidence.
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Affiliation(s)
- Alexander Rau
- Department of Diagnostic and Interventional Radiology, University Hospital, Hugstetter Straße 55, 79106, Freiburg, Germany.
- Department of Neuroradiology, University Hospital, Breisacher Straße 64, 79106, Freiburg, Germany.
| | - Jakob Straehle
- Department of Neurosurgery, University Hospital, Breisacher Straße 64, 79106, Freiburg, Germany
| | - Thomas Stein
- Department of Diagnostic and Interventional Radiology, University Hospital, Hugstetter Straße 55, 79106, Freiburg, Germany
| | - Thierno Diallo
- Department of Diagnostic and Interventional Radiology, University Hospital, Hugstetter Straße 55, 79106, Freiburg, Germany
| | - Stephan Rau
- Department of Diagnostic and Interventional Radiology, University Hospital, Hugstetter Straße 55, 79106, Freiburg, Germany
- Department of Neuroradiology, University Hospital, Breisacher Straße 64, 79106, Freiburg, Germany
| | | | - Konstantin Nikolaou
- Department of Diagnostic and Interventional Radiology, University Tuebingen, Hoppe-Seyler Straße 3, 72076, Tuebingen, Germany
| | - Stefan O Schoenberg
- Department of Radiology and Nuclear Medicine, University Medical Center Mannheim, Heidelberg University, Theodor-Kutzer-Ufer 1-3, 68167, Mannheim, Germany
| | - Daniel Overhoff
- Department of Radiology and Nuclear Medicine, University Medical Center Mannheim, Heidelberg University, Theodor-Kutzer-Ufer 1-3, 68167, Mannheim, Germany
| | - Jürgen Beck
- Department of Neurosurgery, University Hospital, Breisacher Straße 64, 79106, Freiburg, Germany
| | - Horst Urbach
- Department of Neuroradiology, University Hospital, Breisacher Straße 64, 79106, Freiburg, Germany
| | - Jan-Helge Klingler
- Department of Neurosurgery, University Hospital, Breisacher Straße 64, 79106, Freiburg, Germany
| | - Fabian Bamberg
- Department of Diagnostic and Interventional Radiology, University Hospital, Hugstetter Straße 55, 79106, Freiburg, Germany
| | - Jakob Weiss
- Department of Diagnostic and Interventional Radiology, University Hospital, Hugstetter Straße 55, 79106, Freiburg, Germany
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Metal implants on abdominal CT: does split-filter dual-energy CT provide additional value over iterative metal artifact reduction? Abdom Radiol (NY) 2023; 48:424-435. [PMID: 36180598 PMCID: PMC9849167 DOI: 10.1007/s00261-022-03682-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2022] [Revised: 09/09/2022] [Accepted: 09/09/2022] [Indexed: 01/27/2023]
Abstract
PURPOSE To assess image quality and metal artifact reduction in split-filter dual-energy CT (sfDECT) of the abdomen with hip or spinal implants using virtual monoenergetic images (VMI) and iterative metal artifact reduction algorithm (iMAR). METHODS 102 portal-venous abdominal sfDECTs of patients with hip (n = 71) or spinal implants (n = 31) were included in this study. Images were reconstructed as 120kVp-equivalent images (Mixed) and VMI (40-190 keV), with and without iMAR. Quantitative artifact and image noise was measured using 12 different ROIs. Subjective image quality was rated by two readers using a five-point Likert-scale in six categories, including overall image quality and vascular contrast. RESULTS Lowest quantitative artifact in both hip and spinal implants was measured in VMI190keV-iMAR. However, it was not significantly lower than in MixediMAR (for all ROIs, p = 1.00), which were rated best for overall image quality (hip: 1.00 [IQR: 1.00-2.00], spine: 3.00 [IQR:2.00-3.00]). VMI50keV-iMAR was rated best for vascular contrast (hip: 1.00 [IQR: 1.00-2.00], spine: 2.00 [IQR: 1.00-2.00]), which was significantly better than Mixed (both, p < 0.001). VMI50keV-iMAR provided superior overall image quality compared to Mixed for hip (1.00 vs 2.00, p < 0.001) and similar diagnostic image quality for spinal implants (2.00 vs 2.00, p = 0.51). CONCLUSION For abdominal sfDECT with hip or spinal implants MixediMAR images should be used. High keV VMI do not further improve image quality. IMAR allows the use of low keV images (VMI50keV) to improve vascular contrast, compared to Mixed images.
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The Impact of Virtual Monoenergetic Imaging on Visualization of the Cervical Spinal Canal. J Comput Assist Tomogr 2023; 47:160-164. [PMID: 36112014 DOI: 10.1097/rct.0000000000001383] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
RATIONALE AND OBJECTIVES Our purpose is to explore the role of dual-energy computed tomography (DECT) and virtual monoenergetic energy levels in reducing shoulder artifact to improve visualization of the cervical spinal canal. MATERIALS AND METHODS A retrospective review of 171 consecutive DECT scans of the neck (95 male, 65 female; mean age, 60.9 years, ranging from 18 to 88 years; with 11 excluded because of nondiagnostic image quality) during an 8-month period was performed with postprocessing of monoenergetic images at 50, 70, 100, and 140 keV. Subjective comparisons and objective image noise between the monoenergetic images and standard computed tomography (CT) were analyzed by 1-way analysis of variance to determine the optimal DECT energy level with the highest image quality. RESULTS Subjectively, 100-keV DECT best visualizes the spinal canal relative to standard CT, 50 and 70 keV ( P < 0.01), and was superior to 140 keV for reader 1 ( P < 0.01). Objectively, 100 keV demonstrated less noise relative to 50 keV (72.02; P < 0.01). There was no difference in noise between 100 keV and 70 keV, or between 100 keV and standard CT, which also demonstrated lower noise relative to 50-, 70-, and 140-keV levels (91.53, P < 0.01; 29.84, P < 0.01; and 22.66, P < 0.03). CONCLUSION Dual-energy CT at 100 keV may be the preferred DECT monoenergetic level for soft tissue assessment. Increasing energy level is associated with reduction in shoulder artifact, with no difference in noise between 100 keV and standard CT, although 100-keV images may be subjectively better.
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Low-Dose CT Imaging of the Pelvis in Follow-up Examinations-Significant Dose Reduction and Impact of Tin Filtration: Evaluation by Phantom Studies and First Systematic Retrospective Patient Analyses. Invest Radiol 2022; 57:789-801. [PMID: 35776429 DOI: 10.1097/rli.0000000000000898] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
OBJECTIVES Low-dose (LD) computed tomography (CT) is still rarely used in musculoskeletal (MSK) radiology. This study evaluates the potentials of LD CT for follow-up pelvic imaging with special focus on tin filtration (Sn) technology for normal and obese patients with and without metal implants. MATERIALS AND METHODS In a phantom study, 5 different LD and normal-dose (ND) CT protocols with and without tin filtration were tested using a normal and an obese phantom. Iterative reconstruction (IR) and filtered back projection (FBP) were used for CT image reconstruction. In a subsequent retrospective patient study, ND CT images of 45 patients were compared with follow-up tin-filtered LD CT images with a 90% dose reduction. Sixty-four percent of patients contained metal implants at the follow-up examination. Computed tomography images were objectively (image noise, contrast-to-noise ratio [CNR], dose-normalized contrast-to-noise ratio [CNRD]) and subjectively, using a 6-point Likert score, evaluated. In addition, the figure of merit was calculated. For group comparisons, paired t tests, Wilcoxon signed rank test, analysis of variance, or Kruskal-Wallis tests were used, where applicable. RESULTS The LD Sn protocol with 67% dose reduction resulted in equal values in qualitative (Likert score) and quantitative image analysis (image noise) compared with the ND protocol in the phantom study. For follow-up examinations, dose could be reduced up to 90% by using Sn LD CT scans without impairment in the clinical study. However, metal implants resulted in a mild impairment of Sn LD as well as ND CT images. Cancellous bone ( P < 0.001) was assessed worse and cortical bone ( P = 0.063) equally in Sn LD CT images compared with ND CT images. Figure of merit values were significant ( P ≤ 0.02) lower and hence better in Sn LD as in ND protocols. Obese patients benefited in particular from tin filtration in LD MSK imaging in terms of image noise and CNR ( P ≤ 0.05). CONCLUSIONS Low-dose CT scans with tin filtration allow maximum dose reduction while maintaining high image quality for certain clinical purposes, for example, follow-up examinations, especially metal implant position, material loosening, and consolidation controls. Overweight patients benefit particularly from tin filter technology. Although metal implants decrease image quality in ND as well as in Sn LD CT images, this is not a relevant limitation for assessability.
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King J, Whittam S, Smith D, Al-Qaisieh B. The Impact of a Metal Artefact Reduction Algorithm on Treatment Planning for Patients Undergoing Radiotherapy of the Pelvis. Phys Imaging Radiat Oncol 2022; 24:138-143. [DOI: 10.1016/j.phro.2022.11.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Revised: 11/08/2022] [Accepted: 11/08/2022] [Indexed: 11/13/2022] Open
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Kanani A, Yazdi M, Owrangi AM, Karbasi S, Mosleh-Shirazi MA. Metal artifact reduction in cervix brachytherapy with titanium applicators using dual-energy CT through virtual monoenergetic images and an iterative algorithm: A phantom study. Brachytherapy 2022; 21:933-942. [PMID: 35933273 DOI: 10.1016/j.brachy.2022.07.003] [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: 04/06/2022] [Revised: 06/16/2022] [Accepted: 07/02/2022] [Indexed: 12/14/2022]
Abstract
PURPOSE To evaluate an iterative metal-artifact reduction (iMAR) algorithm, dual-energy CT (DECT) through virtual monoenergetic images (VMI), and a combination of iMAR and DECT for reducing metal artifact severity (AS) induced by Fletcher titanium applicators used in cervix brachytherapy, the efficacy of which are hitherto unreported. METHODS AND MATERIALS 120 kVp single-energy CT (SECT) (Siemens) of BEBIG tandem applicators, varying in shape (straight or curved) and diameter (3.5 mm or 5 mm) in a custom-made water-filled phantom, and their DECT images obtained from extrapolation of 80 kVp and 140 kVp, were reconstructed using four methods: DECT through VMI±iMAR, and SECT±iMAR. The DECT images were reconstructed monoenergetically at 70, 150, and 190 keV. AS was evaluated using measured values and statistical analysis. RESULTS iMAR, DECT, and combined DECT and iMAR reduced AS (p < 0.05). DECT had a lower AS than SECT, even without iMAR (p < 0.025). SECT+iMAR was more effective than DECT-iMAR with VMI at 70 and 190 keV (p < 0.05), whereas showing no statistically significant difference at 150 keV. With DECT and iMAR combined, AS was reduced more effectively compared to the SECT+iMAR or DECT alone. It also reduced the mean interobserver uncertainty by 0.2 mm. CONCLUSIONS These findings indicate that iMAR reduces the AS caused by Fletcher titanium applicators for both SECT and DECT, a combination of iMAR and DECT is superior to either strategy alone, and at low energies, DECT+iMAR also produces similar artifact reduction. These practical strategies promise more accurate source-position and structure definitions in CT-based gynecological brachytherapy treatment planning.
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Affiliation(s)
- Abolfazl Kanani
- Ionizing and Non-Ionizing Radiation Protection Research Center (INIRPRC), School of Paramedical Sciences, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Mehran Yazdi
- Signal and Image Processing Lab. (SIPL), School of Electrical and Computer Eng., Shiraz University, Shiraz, Iran
| | - Amir M Owrangi
- Department of Radiation Oncology, UT Southwestern Medical Center, Dallas, TX
| | - Sareh Karbasi
- Physics Unit, Department of Radio-oncology, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Mohammad Amin Mosleh-Shirazi
- Ionizing and Non-Ionizing Radiation Protection Research Center (INIRPRC), School of Paramedical Sciences, Shiraz University of Medical Sciences, Shiraz, Iran; Physics Unit, Department of Radio-oncology, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran.
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Yoo HJ, Hong SH, Choi JY, Chae HD. Comparison of Metal Artifact Reduction Algorithms in Patients with Hip Prostheses: Virtual Monoenergetic Images vs. Orthopedic Metal Artifact Reduction. JOURNAL OF THE KOREAN SOCIETY OF RADIOLOGY 2022; 83:1286-1297. [PMID: 36545406 PMCID: PMC9748456 DOI: 10.3348/jksr.2021.0130] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Revised: 11/12/2021] [Accepted: 12/14/2021] [Indexed: 12/24/2022]
Abstract
Purpose To assess the usefulness of various metal artifact reduction (MAR) methods in patients with hip prostheses. Materials and Methods This retrospective study included 47 consecutive patients who underwent hip arthroplasty and dual-energy CT. Conventional polyenergetic image (CI), orthopedic-MAR (O-MAR), and virtual monoenergetic image (VMI, 50-200 keV) were tested for MAR. Quantitative analysis was performed in seven regions around the prostheses. Qualitative assessments included evaluation of the degree of artifacts and the presence of secondary artifacts. Results The lowest amount of image noise was observed in the O-MAR, followed by the VMI. O-MAR also showed the lowest artifact index, followed by high-keV VMI in the range of 120-200 keV (soft tissue) or 200 keV (bone). O-MAR had the highest contrast-to-noise ratio (CNR) in regions with severe hypodense artifacts, while VMI had the highest CNR in other regions, including the periprosthetic bone. On assessment of the CI of pelvic soft tissues, VMI showed a higher structural similarity than O-MAR. Upon qualitative analysis, metal artifacts were significantly reduced in O-MAR, followed by that in VMI, while secondary artifacts were the most frequently found in the O-MAR (p < 0.001). Conclusion O-MAR is the best technique for severe MAR, but it can generate secondary artifacts. VMI at high keV can be advantageous for evaluating periprosthetic bone.
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Lennartz S, Hokamp NG, Kambadakone A. Dual-Energy CT of the Abdomen: Radiology In Training. Radiology 2022; 305:19-27. [PMID: 35727149 DOI: 10.1148/radiol.212914] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
A 61-year-old man with an esophageal cancer diagnosis underwent staging dual-energy CT of the chest and abdomen in the portal venous phase after contrast media administration. Aside from the primary tumor and suspicious local lymph nodes, CT revealed hypoattenuating ambiguous liver lesions, an incidental right adrenal nodule, and a right renal lesion with soft-tissue attenuation. In addition, advanced atherosclerosis of the abdominal aorta and its major branches was noted. This article provides a case-based review of dual-energy CT technologies and their applications in the abdomen. The clinical utility of virtual monoenergetic images, virtual unenhanced images, and iodine maps is discussed.
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Affiliation(s)
- Simon Lennartz
- From the Institute for Diagnostic and Interventional Radiology, University of Cologne, Faculty of Medicine and University Hospital Cologne, Kerpener Strasse 62, 50937 Cologne, Germany (S.L., N.G.H.); and Department of Radiology, Division of Abdominal Imaging, Massachusetts General Hospital, Boston, Mass (A.K.)
| | - Nils Große Hokamp
- From the Institute for Diagnostic and Interventional Radiology, University of Cologne, Faculty of Medicine and University Hospital Cologne, Kerpener Strasse 62, 50937 Cologne, Germany (S.L., N.G.H.); and Department of Radiology, Division of Abdominal Imaging, Massachusetts General Hospital, Boston, Mass (A.K.)
| | - Avinash Kambadakone
- From the Institute for Diagnostic and Interventional Radiology, University of Cologne, Faculty of Medicine and University Hospital Cologne, Kerpener Strasse 62, 50937 Cologne, Germany (S.L., N.G.H.); and Department of Radiology, Division of Abdominal Imaging, Massachusetts General Hospital, Boston, Mass (A.K.)
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22
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Huflage H, Grunz JP, Hackenbroch C, Halt D, Luetkens KS, Alfred Schmidt AM, Patzer TS, Ergün S, Bley TA, Kunz AS. Metal artefact reduction in low-dose computed tomography: Benefits of tin prefiltration versus postprocessing of dual-energy datasets over conventional CT imaging. Radiography (Lond) 2022; 28:690-696. [PMID: 35728278 DOI: 10.1016/j.radi.2022.05.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Revised: 05/01/2022] [Accepted: 05/30/2022] [Indexed: 11/26/2022]
Abstract
INTRODUCTION The purpose of this study was to determine the potential for metal artefact reduction in low-dose multidetector CT as these pose a frequent challenge in clinical routine. Investigations focused on whether spectral shaping via tin prefiltration, virtual monoenergetic imaging or virtual blend imaging (VBI) offers superior image quality in comparison with conventional CT imaging. METHODS Using a third-generation dual-source CT scanner, two cadaveric specimens with different metal implants (dental, cervical spine, hip, knee) were examined with acquisition protocols matched for radiation dose with regards to tube voltage and current. In order to allow for precise comparison, and due to the relatively short scan lengths, automatic tube current modulation was disabled. Specifically, the following scan protocals were examined: conventional CT protocols (100/120 kVp), tin prefiltration (Sn 100/Sn 150 kVp), VBI and virtual monoenergetic imaging (VME 100/120/150 keV). Mean attenuation and image noise were measured in hyperdense and hypodense artefacts, in artefact-impaired and artefact-free soft tissue. Subjective image quality was rated independently by three radiologists. RESULTS Objectively, Sn 150 kVp allowed for the best reduction of hyperdense streak artefacts (p < 0.001), while VME 150 keV and Sn 150 kVp protocols facilitated equally good reduction of hypodense artefacts (p = 0.173). Artefact-impaired soft tissue attenuation was lowest in Sn 150 kVp protocols (p ≤ 0.011), whereas all VME showed significantly less image noise compared to conventional or tin-filtered protocols (p ≤ 0.001). Subjective assessment favoured Sn 150 kVp regarding hyperdense streak artefacts and delineation of cortical bone (p ≤ 0.005). The intraclass correlation coefficient was 0.776 (95% confidence interval: 0.712-0.831; p < 0.001) indicating good interrater reliability. CONCLUSION In the presence of metal implants in our cadaveric study, tin prefiltration with 150 kVp offers superior artefact reduction for low-dose CT imaging of osseous tissue compared with virtual monoenergetic images of dual-energy datasets. The delineation of cortical boundaries seems to benefit particularly from spectral shaping. IMPLICATIONS FOR PRACTICE Low-dose CT imaging of osseous tissue in combination with tin prefiltration allows for superior metal artefact reduction when compared to virtual monoenergetic images of dual-energy datasets. Employing this technique ought to be considered in daily routine when metal implants are present within the scan volume as findings suggest it allows for radiation dose reduction and facilitates diagnosis relevant to further treatment.
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Affiliation(s)
- H Huflage
- Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Oberdürrbacher Straße 6, 97080 Würzburg, Germany.
| | - J-P Grunz
- Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Oberdürrbacher Straße 6, 97080 Würzburg, Germany.
| | - C Hackenbroch
- Department of Diagnostic and Interventional Radiology and Neuroradiology, German Armed Forces Hospital Ulm, Oberer Eselsberg 40, 89081 Ulm, Germany; Department of Diagnostic and Interventional Radiology, University Hospital Ulm, Albert-Einstein-Allee 23, 89081 Ulm, Germany.
| | - D Halt
- Department of Diagnostic and Interventional Radiology and Neuroradiology, German Armed Forces Hospital Ulm, Oberer Eselsberg 40, 89081 Ulm, Germany.
| | - K S Luetkens
- Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Oberdürrbacher Straße 6, 97080 Würzburg, Germany.
| | - A M Alfred Schmidt
- Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Oberdürrbacher Straße 6, 97080 Würzburg, Germany.
| | - T S Patzer
- Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Oberdürrbacher Straße 6, 97080 Würzburg, Germany.
| | - S Ergün
- Institute of Anatomy and Cell Biology, University of Würzburg, Koellikerstraße 6, 97070 Würzburg, Germany.
| | - T A Bley
- Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Oberdürrbacher Straße 6, 97080 Würzburg, Germany.
| | - A S Kunz
- Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Oberdürrbacher Straße 6, 97080 Würzburg, Germany.
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Hackenbroch C, Schüle S, Halt D, Zengerle L, Beer M. Metal Artifact Reduction With Tin Prefiltration in Computed Tomography: A Cadaver Study for Comparison With Other Novel Techniques. Invest Radiol 2022; 57:194-203. [PMID: 34482356 DOI: 10.1097/rli.0000000000000823] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVES With the aging population and thus rising numbers of orthopedic implants (OIs), metal artifacts (MAs) increasingly pose a problem for computed tomography (CT) examinations. In the study presented here, different MA reduction techniques (iterative metal artifact reduction software [iMAR], tin prefilter technique, and dual-energy CT [DECT]) were compared. MATERIALS AND METHODS Four human cadaver pelvises with OIs were scanned on a third-generation DECT scanner using tin prefilter (Sn), dual-energy (DE), and conventional protocols. Virtual monoenergetic CT images were generated from DE data sets. Postprocessing of CT images was performed using iMAR. Qualitative (bony structures, MA, image noise) image analysis using a 6-point Likert scale and quantitative image analysis (contrast-to-noise ratio, standard deviation of background noise) were performed by 2 observers. Statistical testing was performed using Friedman test with Nemenyi test as a post hoc test. RESULTS The iMAR Sn 150 kV protocol provided the best overall assessability of bony structures and the lowest subjective image noise. The iMAR DE protocol and virtual monochromatic image (VMI) ± iMAR achieved the most effective metal artifact reduction (MAR) (P < 0.05 compared with conventional protocols). Bony structures were rated worse in VMI ± iMAR (P < 0.05) than in tin prefilter protocols ± iMAR. The DE protocol ± iMAR had the lowest contrast-to-noise ratio (P < 0.05 compared with iMAR standard) and the highest image noise (P < 0.05 compared with iMAR VMI). The iMAR reduced MA very efficiently. CONCLUSIONS When considering MAR and image quality, the iMAR Sn 150 kV protocol performed best overall in CT images with OI. The iMAR generated new artifacts that impaired image quality. The DECT/VMI reduced MA best, but experienced from a lack of resolution of bony fine structures.
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Affiliation(s)
| | - Simone Schüle
- From the Department of Diagnostic and Interventional Radiology and Neuroradiology, German Armed Forces Hospital of Ulm
| | - Daniel Halt
- From the Department of Diagnostic and Interventional Radiology and Neuroradiology, German Armed Forces Hospital of Ulm
| | - Laura Zengerle
- Institute of Orthopaedic Research and Biomechanics, University Hospital of Ulm, Ulm, Germany
| | - Meinrad Beer
- Department of Diagnostic and Interventional Radiology
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Vara G, Ceccarelli L, Ponti F, Miceli M, Golfieri R, Facchini G. Reduction of Metal Artifacts Caused by Titanium Peduncular Screws in the Spine by Means of Monoenergetic Images and the Metal Artifact Reduction Software in Dual-Energy Computed Tomography. J Med Phys 2022; 47:152-158. [PMID: 36212200 PMCID: PMC9543003 DOI: 10.4103/jmp.jmp_121_21] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Revised: 03/08/2022] [Accepted: 03/09/2022] [Indexed: 11/04/2022] Open
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Combination of Iterative Metal Artifact Reduction and Virtual Monoenergetic Reconstruction Using Split-Filter Dual-Energy CT in Patients With Dental Artifact on Head and Neck CT. AJR Am J Roentgenol 2021; 218:716-727. [PMID: 34755521 DOI: 10.2214/ajr.21.26772] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Background: Head and neck CT may be limited by dental hardware artifact. Both post-processing based iterative metal artifact reduction (iMAR) and virtual monoenergetic reconstruction (VMR) from dual-energy CT (DECT) can reduce metal artifact. Their combination is poorly described for single-source DECT systems. Objective: To compare metal artifact reduction between VMR, iMAR, and their combination, using split-filter single-source DECT in patients with severe dental hardware artifact. Methods: This retrospective study included 44 patients (9 female, 35 male; mean age 66.0±10.4 years) who underwent head and neck CT exhibiting severe dental hardware artifact. Standard images, VMR, iMAR, and VMRi-MAR were reconstructed; VMR and VMRiMAR used 40, 70, 100, 120, 150, and 190 keV. ROIs were placed to measure corrected attenuation in pronounced hyperattenuating and hypoattenuating artifacts and artifact-impaired soft tissue, as well as corrected artifact-impaired soft tissue noise. Two radiologists independently assessed soft tissue interpretability (1-5 scale); pooled ratings were analyzed. Readers selected the preferred reconstruction for each patient. Results: Mean hyperattenuating artifact corrected attenuation was 521.0 for standard, 496.4-892.2 for VMR, 48.2 for iMAR, and 32.8-91.0 for VMRiMAR. Mean hypoattenuating artifact corrected attenuation was -455.1 for standard, -408.5 to -679.9 for VMR, -37.3 for iMAR, and -17.8 to -36.9 for VMRiMAR. Mean artifact-impaired soft tissue corrected attenuation was 10.8 for standard, -0.6 to 24.9 for VMR, 4.3 for iMAR, and -2.0 to 7.8 for VMRiMAR. Mean artifact-impaired soft tissue corrected noise was 58.7 for standard, 38.2-129.7 for VMR, 11.0 for iMAR, and 5.8-45.6 for VMRiMAR. Median soft tissue interpretability was 1.2 for standard, 1.1-1.2 for VMR, 3.7 for iMAR, and 2.0-3.8 for VMRiMAR. Artifact-impaired soft tissue corrected attenuation and soft tissue interpretability were significantly improved (p<.05) for VMRiMAR versus iMAR only at 100 keV. Readers preferred VMRiMAR at 100 keV in 56.8% and 59.1% of examinations. Conclusion: For reducing severe dental material artifact, iMAR has greater impact than VMR. Though iMAR and VMRiMAR were overall similar, VMRiMAR exhibited small benefit at 100 keV. Clinical Impact: VMR and iMAR techniques, using split-filter DECT, may be combined for clinical head and neck imaging to reduce artifact from dental hardware and improve image quality.
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Wang G, Gao Q, Wang Z, Lu X, Yu S, Jin Z. Reduction of microwave ablation needle related metallic artifacts using virtual monoenergetic images from dual-layer detector spectral CT in a rabbit model with VX2 tumor. Sci Rep 2021; 11:9295. [PMID: 33927327 PMCID: PMC8085209 DOI: 10.1038/s41598-021-88853-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Accepted: 04/16/2021] [Indexed: 12/03/2022] Open
Abstract
The purpose of the study was to investigate the application of virtual monoenergetic images (VMIs) in reducing metal artifacts in rabbit VX2 liver cancer models treated with microwave ablation (MWA) therapy. A total of 31 VX2 liver cancer models that accepted CT-guided percutaneous microwave ablation were analyzed. Conventional images (CIs) with the most severe metallic artifacts and their corresponding energy levels from 40 to 200 keV with 10 keV increment of VMIs were reconstructed for further analysis. Objective image analysis was assessed by recording the attenuation (HU) and standard deviation of the most severe hyper/hypodense artifacts as well as artifact-impaired liver parenchyma tissue. Two radiologists visually evaluated the extent of artifact reduction, assessed data obtained by a diagnostic evaluation of liver tissues, and appraised the appearance of new artifacts according to the grade score. Statistical analysis was performed to compare the difference between CIs and each energy level of VMIs. For subjective assessment, reductions in hyperdense and hypodense artifacts were observed at 170–200 keV and 160–200 keV, respectively. The outcomes of the diagnostic evaluation of adjacent liver tissue were statistically higher at 140–200 keV for VMIs than for CIs. In terms of objective evaluation results, VMIs at 90–200 keV reduced the corrected attenuation of hyperdense and of artifact-impaired liver parenchyma compared with CIs (P < 0.001). When VMIs at 80–200 keV decreased the hypodense artifacts (P < 0.001). Therefore, we concluded that VMIs at 170–200 keV can obviously decrease the microwave ablation needle-related metal artifacts objectively and subjectively in rabbit VX2 liver cancer models.
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Affiliation(s)
- Guorong Wang
- Department of Radiology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, No.1 Shuaifuyuan Wangfujing Dongcheng District, Beijing, 100730, China
| | - Qinzong Gao
- Department of Radiology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, No.1 Shuaifuyuan Wangfujing Dongcheng District, Beijing, 100730, China
| | - Zhiwei Wang
- Department of Radiology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, No.1 Shuaifuyuan Wangfujing Dongcheng District, Beijing, 100730, China.
| | - Xiaomei Lu
- CT Clinical Science, Philips Healthcare, Shenyang, 110016, China
| | - Shenghui Yu
- CT Clinical Science, Philips Healthcare, Beijing, 100600, China
| | - Zhengyu Jin
- Department of Radiology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, No.1 Shuaifuyuan Wangfujing Dongcheng District, Beijing, 100730, China.
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Hamid S, Nasir MU, So A, Andrews G, Nicolaou S, Qamar SR. Clinical Applications of Dual-Energy CT. Korean J Radiol 2021; 22:970-982. [PMID: 33856133 PMCID: PMC8154785 DOI: 10.3348/kjr.2020.0996] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 11/16/2020] [Accepted: 11/22/2020] [Indexed: 01/05/2023] Open
Abstract
Dual-energy CT (DECT) provides insights into the material properties of tissues and can differentiate between tissues with similar attenuation on conventional single-energy imaging. In the conventional CT scanner, differences in the X-ray attenuation between adjacent structures are dependent on the atomic number of the materials involved, whereas in DECT, the difference in the attenuation is dependent on both the atomic number and electron density. The basic principle of DECT is to obtain two datasets with different X-ray energy levels from the same anatomic region and material decomposition based on attenuation differences at different energy levels. In this article, we discuss the clinical applications of DECT and its potential robust improvements in performance and postprocessing capabilities.
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Affiliation(s)
- Saira Hamid
- Department of Radiology, University of British Columbia Hospital, University of British Columbia, Vancouver, Canada.
| | - Muhammad Umer Nasir
- Department of Medical Imaging, Vancouver General Hospital, University of British Columbia, Vancouver, Canada
| | - Aaron So
- Department of Medical Biophyics, Schulich School of Medicine and Dentistry Western University London, Ontario, Canada
| | - Gordon Andrews
- Department of Radiology, University of British Columbia Hospital, University of British Columbia, Vancouver, Canada
| | - Savvas Nicolaou
- Department of Medical Imaging, Vancouver General Hospital, University of British Columbia, Vancouver, Canada
| | - Sadia Raheez Qamar
- Department of Medical Imaging, Sunnybrook Hospital, University of Toronto, Toronto, Canada
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Low-Dose MDCT of Patients With Spinal Instrumentation Using Sparse Sampling: Impact on Metal Artifacts. AJR Am J Roentgenol 2021; 216:1308-1317. [PMID: 33703925 DOI: 10.2214/ajr.20.23083] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
OBJECTIVE. The purpose of our study was to evaluate simulated sparse-sampled MDCT combined with statistical iterative reconstruction (SIR) for low-dose imaging of patients with spinal instrumentation. MATERIALS AND METHODS. Thirty-eight patients with implanted hardware after spinal instrumentation (24 patients with short- or long-term instrumentation-related complications [i.e., adjacent segment disease, screw loosening or implant failure, or postoperative hematoma or seroma] and 14 control subjects with no complications) underwent MDCT. Scans were simulated as if they were performed with 50% (P50), 25% (P25), 10% (P10), and 5% (P5) of the projections of the original acquisition using an in-house-developed SIR algorithm for advanced image reconstructions. Two readers performed qualitative image evaluations of overall image quality and artifacts, image contrast, inspection of the spinal canal, and diagnostic confidence (1 = high, 2 = medium, and 3 = low confidence). RESULTS. Although overall image quality decreased and artifacts increased with reductions in the number of projections, all complications were detected by both readers when 100% of the projections of the original acquisition (P100), P50, and P25 imaging data were used. For P25 data, diagnostic confidence was still high (mean score ± SD: reader 1, 1.2 ± 0.4; reader 2, 1.3 ± 0.5), and interreader agreement was substantial to almost perfect (weighted Cohen κ = 0.787-0.855). The mean volumetric CT dose index was 3.2 mGy for P25 data in comparison with 12.6 mGy for the original acquisition (P100 data). CONCLUSION. The use of sparse sampling and SIR for low-dose MDCT in patients with spinal instrumentation facilitated considerable reductions in radiation exposure. The use of P25 data with SIR resulted in no missed complications related to spinal instrumentation and allowed high diagnostic confidence, so using only 25% of the projections is probably enough for accurate and confident diagnostic detection of major instrumentation-related complications.
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Li H, Wang S, Tang J, Wu J, Liu Y. Computed Tomography- (CT-) Based Virtual Surgery Planning for Spinal Intervertebral Foraminal Assisted Clinical Treatment. JOURNAL OF HEALTHCARE ENGINEERING 2021; 2021:5521916. [PMID: 33747415 PMCID: PMC7960066 DOI: 10.1155/2021/5521916] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 02/20/2021] [Accepted: 03/01/2021] [Indexed: 11/26/2022]
Abstract
With the development of minimally invasive spine concepts and the introduction of new minimally invasive instruments, minimally invasive spine technology, represented by foraminoscopy, has flourished, and percutaneous foraminoscopy has become one of the most reliable minimally invasive procedures for the treatment of lumbar disc herniation. Percutaneous foraminoscopy is a safe and effective minimally invasive spinal endoscopic surgical technique. It fully protects the paravertebral muscles and soft tissues as well as the posterior column structure of the spine, provides precise treatment of the target nucleus pulposus tissue, with the advantages of less surgical trauma, fewer postoperative complications, and rapid postoperative recovery, and is widely promoted and used in clinical practice. In this paper, we can view the location, morphology, structure, alignment, and adjacency relationships by performing coronary, CT, and diagonal reconstruction along the attachment of the yellow ligaments and performing 3D reconstruction or processing techniques after performing CT scans. This allows clinicians to observe the laminoplasty and the stenosis of the vertebral canal in a more intuitive and overall manner. It has clinical significance for the display of the sublaminar spine as well as the physician's judgment of the disease and the choice of surgery.
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Affiliation(s)
- Hao Li
- Department of Orthopaedics, Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu 221000, China
| | - Song Wang
- Department of Orthopaedics, Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu 221000, China
| | - Jinlong Tang
- Department of Orthopaedics, Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu 221000, China
| | - Jibin Wu
- Department of Orthopaedics, Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu 221000, China
| | - Yong Liu
- Department of Orthopaedics, Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu 221000, China
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Reduction of CT artifacts from cardiac implantable electronic devices using a combination of virtual monoenergetic images and post-processing algorithms. Eur Radiol 2021; 31:7151-7161. [PMID: 33630164 PMCID: PMC8379133 DOI: 10.1007/s00330-021-07746-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 12/16/2020] [Accepted: 02/04/2021] [Indexed: 12/20/2022]
Abstract
OBJECTIVES To evaluate the reduction of artifacts from cardiac implantable electronic devices (CIEDs) by virtual monoenergetic images (VMI), metal artifact reduction (MAR) algorithms, and their combination (VMIMAR) derived from spectral detector CT (SDCT) of the chest compared to conventional CT images (CI). METHODS In this retrospective study, we included 34 patients (mean age 74.6 ± 8.6 years), who underwent a SDCT of the chest and had a CIED in place. CI, MAR, VMI, and VMIMAR (10 keV increment, range: 100-200 keV) were reconstructed. Mean and standard deviation of attenuation (HU) among hypo- and hyperdense artifacts adjacent to CIED generator and leads were determined using ROIs. Two radiologists qualitatively evaluated artifact reduction and diagnostic assessment of adjacent tissue. RESULTS Compared to CI, MAR and VMIMAR ≥ 100 keV significantly increased attenuation in hypodense and significantly decreased attenuation in hyperdense artifacts at CIED generator and leads (p < 0.05). VMI ≥ 100 keV alone only significantly decreased hyperdense artifacts at the generator (p < 0.05). Qualitatively, VMI ≥ 100 keV, MAR, and VMIMAR ≥ 100 keV provided significant reduction of hyper- and hypodense artifacts resulting from the generator and improved diagnostic assessment of surrounding structures (p < 0.05). Diagnostic assessment of structures adjoining to the leads was only improved by MAR and VMIMAR 100 keV (p < 0.05), whereas keV values ≥ 140 with and without MAR significantly worsened diagnostic assessment (p < 0.05). CONCLUSIONS The combination of VMI and MAR as well as MAR as a standalone approach provides effective reduction of artifacts from CIEDs. Still, higher keV values should be applied with caution due to a loss of soft tissue and vessel contrast along the leads. KEY POINTS • The combination of VMI and MAR as well as MAR as a standalone approach enables effective reduction of artifacts from CIEDs. • Higher keV values of both VMI and VMIMAR at CIED leads should be applied with caution since diagnostic assessment can be hampered by a loss of soft tissue and vessel contrast. • Recommended keV values for CIED generators are between 140 and 200 keV and for leads around 100 keV.
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Sun X, Zhao Q, Sun P, Yao Z, Wang R. Metal artifact reduction using mono-energy images combined with metal artifact reduction software in spectral computed tomography: a study on phantoms. Quant Imaging Med Surg 2020; 10:1515-1525. [PMID: 32676369 DOI: 10.21037/qims-19-936] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
BACKGROUND This study aimed to evaluate the effectiveness of spectral computed tomography (CT) mono-energy imaging combined with metal artifact reduction software (MARs) for metal implant artifact reduction using a phantom. METHODS A quantitative standard phantom with 9 cylinders was used to simulate the attenuation of the different tissues of the human body around the metal implant. Groups A and B were divided according to conventional CT scan mode and spectral CT scan mode. Three sets of reconstructed images, including 120 kVp-like + MARs images, mono-energy images (MonoE), and MonoE + MARs images, were generated after spectral CT scanning. High-attenuation artifacts and low-attenuation artifacts were observed around the coil in the images of groups A and B. The CT values (Hounsfield unit) and standard deviation (SD) values of the artifacts were measured, and the artifact index and hardening artifact removal rate were calculated. RESULTS Compared to conventional poly-energy CT images, for high-attenuation and low-attenuation artifacts, the artifact indices of 120 kVp-like + MARs, MonoE, and MonoE + MARs images were all reduced significantly. The hardening artifact removal rates of the high-attenuation and low-attenuation artifacts of 120 kVp-like + MARs images were 82% and 92%, respectively. The hardening artifact removal rate of the high-attenuation and low-attenuation artifacts of MonoE and MonoE + MARs images increased with the mono-energy level. CONCLUSIONS Spectral CT using the 120 kVp-like + MARs, 110-140 keV MonoE, and MonoE + MARs reconstruction methods can reduce metal implant artifacts in varying degrees. MonoE + MARs reconstruction was the best method for reducing metal artifacts.
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Affiliation(s)
- Xiaoli Sun
- Department of Radiology, Beijing Shijitan Hospital, Peking University Ninth School of Clinical Medicine, Capital Medical University, Beijing, China
| | - Qingqing Zhao
- Department of Radiology, Beijing Shijitan Hospital, Peking University Ninth School of Clinical Medicine, Capital Medical University, Beijing, China
| | - Pengtao Sun
- Department of Radiology, Beijing Shijitan Hospital, Peking University Ninth School of Clinical Medicine, Capital Medical University, Beijing, China
| | - Zhipeng Yao
- Department of Radiology, Beijing Shijitan Hospital, Peking University Ninth School of Clinical Medicine, Capital Medical University, Beijing, China
| | - Rengui Wang
- Department of Radiology, Beijing Shijitan Hospital, Peking University Ninth School of Clinical Medicine, Capital Medical University, Beijing, China
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Combined use of virtual monochromatic images and projection-based metal artifact reduction methods in evaluation of total knee arthroplasty. Eur Radiol 2020; 30:5298-5307. [PMID: 32424592 DOI: 10.1007/s00330-020-06932-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Accepted: 04/30/2020] [Indexed: 10/24/2022]
Abstract
OBJECTIVES To evaluate the effect of the combined use of virtual monochromatic imaging (VMI) and projection-based metal artifact reduction (PB-MAR) methods on further artifact reduction and image quality in total knee arthroplasty (TKA) patients. METHODS Fifty-seven knee joints from 36 patients who had a previous history of TKA for bilateral or unilateral knee joints were included in this study. Four sets of images were compared between non-MAR, PB-MAR, VMI, and VMI + PB-MAR. For quantitative analysis, the area, mean attenuation, artifact index (AI), and contrast-to-noise ratio (CNR) were calculated for each protocol. Regarding qualitative analysis, overall artifact and depiction of soft tissue and bony structure were compared using relative visual grading analysis. RESULTS In the femoral region, the VMI + PB-MAR protocol showed the best MAR performance in quantitative measures including area, mean attenuation, and AI (p < .001). However, MAR protocols with VMI showed significantly lower CNRs than did the protocols without VMI in the tibial region (p < .001). On qualitative analysis, VMI + PB-MAR also showed fewer overall artifacts than did the other two MAR protocols. Soft tissue was best depicted in VMI + PB-MAR protocol, and PB-MAR showed the best performance for the depiction of bony structure (p < .001). CONCLUSIONS The combined use of VMI and PB-MAR showed better MAR performance than did PB-MAR or VMI alone. In areas with severe metal artifacts, the VMI + PB-MAR and PB-MAR protocols were useful for the evaluation of soft tissue and bone structure, respectively. KEY POINTS • The combination of artifact reduction methods is effective in reducing metal artifacts in CT. • Soft tissue was best depicted in the combined protocol of projection- and dual-energy-based methods, and projection-based protocol showed the best performance for the depiction of bone structure in case of severe metal artifacts.
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Große Hokamp N, Eck B, Siedek F, Pinto Dos Santos D, Holz JA, Maintz D, Haneder S. Quantification of metal artifacts in computed tomography: methodological considerations. Quant Imaging Med Surg 2020; 10:1033-1044. [PMID: 32489927 DOI: 10.21037/qims.2020.04.03] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Numerous methods for artifact quantification in computed tomography (CT) imaging have been suggested. This study evaluated their utility with regards to correspondence with visual artifact perception and reproducibility. Two titanium rods (5 and 10 mm) were examined with 25 different scanning- and image-reconstruction parameters resulting in different types and extents of artifacts. Four radiologists evaluated every image against each other using an in-house developed software. Rating was repeated two times (2,400 comparisons = 2 times × 4 readers × 300 comparisons). Rankings were combined to obtain a reference ranking. Proposed approaches for artifact quantification include manual measurement of attenuation, standard deviation and noise and sophisticated algorithm-based approaches within the image- and frequency-domain. Two radiologists conducted manual measurements twice while the aforementioned algorithms were implemented within the Matlab-Environment allowing for automated image analysis. The reference ranking was compared to all aforementioned methods for artifact quantification to identify suited approaches. Besides visual analysis, Kappa-statistics and intraclass correlation coefficients (ICC) were used. Intra- and Inter-reader agreements of visual artifact perception were excellent (ICC 0.85-0.92). No quantitative method was able to represent the exact ranking of visually perceived artifacts; however, ICC for manual measurements were low (ICC 0.25-0.97). The method that showed best correspondence and reproducibility used a Fourier-transformed linear ROI and lower-end frequency bins. Automated measurements of artifact extent should be preferred over manual measurements as the latter show a limited reproducibility. One method that allows for automated quantification of such artefacts is made available as an electronic supplement.
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Affiliation(s)
- Nils Große Hokamp
- Institute for Diagnostic and Interventional Radiology, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne, Germany.,Department of Radiology, Case Western Reserve University, Cleveland, OH, USA.,Department of Radiology, University Hospitals Medical Center, Cleveland, OH, USA
| | - Brendan Eck
- Department of Radiology, Case Western Reserve University, Cleveland, OH, USA
| | - Florian Siedek
- Institute for Diagnostic and Interventional Radiology, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne, Germany
| | - Daniel Pinto Dos Santos
- Institute for Diagnostic and Interventional Radiology, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne, Germany
| | - Jasmin A Holz
- Institute for Diagnostic and Interventional Radiology, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne, Germany
| | - David Maintz
- Institute for Diagnostic and Interventional Radiology, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne, Germany
| | - Stefan Haneder
- Institute for Diagnostic and Interventional Radiology, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne, Germany
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Zopfs D, Lennartz S, Pennig L, Glauner A, Abdullayev N, Bremm J, Große Hokamp N, Persigehl T, Kabbasch C, Borggrefe J, Laukamp KR. Virtual monoenergetic images and post-processing algorithms effectively reduce CT artifacts from intracranial aneurysm treatment. Sci Rep 2020; 10:6629. [PMID: 32313094 PMCID: PMC7170914 DOI: 10.1038/s41598-020-63574-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Accepted: 04/01/2020] [Indexed: 11/09/2022] Open
Abstract
To evaluate artifact reduction by virtual monoenergetic images (VMI) and metal artifact reduction algorithms (MAR) as well as the combination of both approaches (VMIMAR) compared to conventional CT images (CI) as standard of reference. In this retrospective study, 35 patients were included who underwent spectral-detector CT (SDCT) with additional MAR-reconstructions due to artifacts from coils or clips. CI, VMI, MAR and VMIMAR (range: 100-200 keV, 10 keV-increment) were reconstructed. Region-of-interest based objective analysis was performed by assessing mean and standard deviation of attenuation (HU) in hypo- and hyperdense artifacts from coils and clips. Visually, extent of artifact reduction and diagnostic assessment were rated. Compared to CI, VMI ≥ 100 keV, MAR and VMIMAR between 100-200 keV increased attenuation in hypoattenuating artifacts (CI/VMI200keV/MAR/VMIMAR200keV, HU: -77.6 ± 81.1/-65.1 ± 103.2/-36.9 ± 27.7/-21.1 ± 26.7) and decreased attenuation in hyperattenuating artifacts (HU: 47.4 ± 32.3/42.1 ± 50.2/29.5 ± 18.9/20.8 ± 25.8). However, differences were only significant for MAR in hypodense and VMIMAR in hypo- and hyperdense artifacts (p < 0.05). Visually, hypo- and hyperdense artifacts were significantly reduced compared to CI by VMI≥140/100keV, MAR and VMIMAR≥100keV. Diagnostic assessment of surrounding brain tissue was significantly improved in VMI≥100keV, MAR and VMIMAR≥100keV. The combination of VMI and MAR facilitates a significant reduction of artifacts adjacent to intracranial coils and clips. Hence, if available, these techniques should be combined for optimal reduction of artifacts following intracranial aneurysm treatment.
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Affiliation(s)
- David Zopfs
- Institute for Diagnostic and Interventional Radiology, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne, Germany
| | - Simon Lennartz
- Institute for Diagnostic and Interventional Radiology, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne, Germany
- Else Kröner Forschungskolleg Clonal Evolution in Cancer, University Hospital Cologne, Weyertal 115b, 50931, Cologne, Germany
| | - Lenhard Pennig
- Institute for Diagnostic and Interventional Radiology, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne, Germany
| | - Andreas Glauner
- Institute for Diagnostic and Interventional Radiology, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne, Germany
| | - Nuran Abdullayev
- Institute for Diagnostic and Interventional Radiology, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne, Germany
| | - Johannes Bremm
- Institute for Diagnostic and Interventional Radiology, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne, Germany
| | - Nils Große Hokamp
- Institute for Diagnostic and Interventional Radiology, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne, Germany
| | - Thorsten Persigehl
- Institute for Diagnostic and Interventional Radiology, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne, Germany
| | - Christoph Kabbasch
- Institute for Diagnostic and Interventional Radiology, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne, Germany
| | - Jan Borggrefe
- Institute for Diagnostic and Interventional Radiology, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne, Germany
| | - Kai Roman Laukamp
- Institute for Diagnostic and Interventional Radiology, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne, Germany.
- University Hospitals Cleveland Medical Center, Department of Radiology, Cleveland, OH, USA.
- Case Western Reserve University, Department of Radiology, Cleveland, OH, USA.
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Laukamp KR, Große Hokamp N, Alabar O, Obmann VC, Lennartz S, Zopfs D, Gilkeson R, Ramaiya N, Gupta A. Metal artifacts from sternal wires: evaluation of virtual monoenergetic images from spectral-detector CT for artifact reduction. Clin Imaging 2020; 60:249-256. [DOI: 10.1016/j.clinimag.2019.12.018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Revised: 12/22/2019] [Accepted: 12/27/2019] [Indexed: 10/25/2022]
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Wei Y, Jia F, Hou P, Zha K, Pu S, Gao J. Clinical application of multi-material artifact reduction (MMAR) technique in Revolution CT to reduce metallic dental artifacts. Insights Imaging 2020; 11:32. [PMID: 32140871 PMCID: PMC7058730 DOI: 10.1186/s13244-020-0836-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Accepted: 01/23/2020] [Indexed: 12/12/2022] Open
Abstract
Background This study aimed to explore the performance of Revolution CT virtual monoenergetic images (VMI) combined with the multi-material artifact reduction (MMAR) technique in reducing metal artifacts in oral and maxillofacial imaging. Results There were significant differences in image quality scores between VMI + MMAR images and VMI+MARS (multiple artifact reduction system) images at each monochromatic energy level (p = 0.000). Compared with the MARS technology, the MMAR technology further reduced metal artifacts and improved the image quality. At VMI90 keV and VMI110 keV, the SD, CNR, and AI in the Revolution CT group were significantly lower than in the Discovery CT, but no significant differences in these parameters were found between two groups at VMI50 keV, VMI70 keV, and VMI130 keV (p > 0.05). The attenuation was comparable between two groups at any energy level (p > 0.05). Conclusions Compared with the MARS reconstruction technique of Discovery CT, the MMAR technique of Revolution CT is better to reduce the artifacts of dental implants in oral and maxillofacial imaging, which improves the image quality and the diagnostic value of surrounding soft tissues.
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Affiliation(s)
- Yijuan Wei
- Department of Radiology, the First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450000, Henan, China
| | - Fei Jia
- Department of Radiation Oncology, the First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450000, Henan, China
| | - Ping Hou
- Department of Radiology, the First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450000, Henan, China
| | - Kaiji Zha
- Department of Radiology, the First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450000, Henan, China
| | - Shi Pu
- Department of Radiology, the First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450000, Henan, China
| | - Jianbo Gao
- Department of Radiology, the First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450000, Henan, China.
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Laukamp KR, Zopfs D, Wagner A, Lennartz S, Pennig L, Borggrefe J, Ramaiya N, Große Hokamp N. CT artifacts from port systems: Virtual monoenergetic reconstructions from spectral-detector CT reduce artifacts and improve depiction of surrounding tissue. Eur J Radiol 2019; 121:108733. [PMID: 31739270 DOI: 10.1016/j.ejrad.2019.108733] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Revised: 10/19/2019] [Accepted: 10/27/2019] [Indexed: 11/27/2022]
Abstract
PURPOSE CT artifacts from port-systems are a common problem in staging- and restaging-examinations and reduce image quality and diagnostic assessment. The purpose of this study was to investigate the reduction of these artifacts using virtual monoenergetic images (VMI) from dual-energy spectral-detector CT (SDCT) in comparison to conventional CT-images (CI). METHOD 50 SDCT-datasets of patients with artifacts from port-chamber and port-catheters were included in this IRB-approved, retrospective study. CI and VMI (range, 40-200 keV, 10 keV increment) were reconstructed from the same acquisition. The quantitative image analysis was performed ROI-based assessing mean and standard deviation of attenuation (HU) in most pronounced hypo- and hyperdense artifacts surrounding to the port-chamber and the distal end of the port-catheter in the superior vena cava. Subjectively, artifact reduction and diagnostic assessment of surrounding soft tissue were rated on 5-point Likert-scales. RESULTS In comparison to CI, VMI of higher keV-values showed strong reduction of hypo- and hyperattenuating artifacts around the port-chamber and port-catheter (CI/VMI200keV: hypodense -104.7 ± 124.7HU/10.8 ± 58.1HU and -101.6 ± 101.5HU/-36.7 ± 32.9HU; hyperdense 240.8 ± 151.6HU/79.6 ± 81.3HU and 108.6 ± 129.3HU/25.9 ± 31.9HU; all p < 0.001). Image noise could also be reduced significantly. The subjective analysis showed significantly reduced artifacts around the port-chamber and port-catheter (CI/VMI200keV: hypodense 3(1-4)/5(4-5) and 3(2-4)/5(4-5); hyperdense 3(1-4)/5(4-5) and 3(2-3)/5(3-5); all p < 0.001) and improved diagnostic assessment of pectoral/subclavian soft tissue for VMI of ≥100keV. Ratings for diagnostic assessment were best between 140-200 keV. Overall interrater agreement was high (ICC = 0.79). CONCLUSIONS Higher keV VMI enabled a significant reduction of artifacts from port-systems around the chamber and the catheter leading to improved assessment of surrounding soft tissue.
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Affiliation(s)
- Kai Roman Laukamp
- Institute for Diagnostic and Interventional Radiology, Faculty of Medicine and University Hospital Cologne, University of Cologne, Kerpener Straße 62, 50937, Cologne, Germany; Department of Radiology, University Hospitals Cleveland Medical Center, 11000 Euclid Ave, 44106 Cleveland, OH, USA; Department of Radiology, Case Western Reserve University, 10900 Euclid Ave, 44106, Cleveland, OH, USA.
| | - David Zopfs
- Institute for Diagnostic and Interventional Radiology, Faculty of Medicine and University Hospital Cologne, University of Cologne, Kerpener Straße 62, 50937, Cologne, Germany
| | - Anton Wagner
- Institute for Diagnostic and Interventional Radiology, Faculty of Medicine and University Hospital Cologne, University of Cologne, Kerpener Straße 62, 50937, Cologne, Germany
| | - Simon Lennartz
- Institute for Diagnostic and Interventional Radiology, Faculty of Medicine and University Hospital Cologne, University of Cologne, Kerpener Straße 62, 50937, Cologne, Germany
| | - Lenhard Pennig
- Institute for Diagnostic and Interventional Radiology, Faculty of Medicine and University Hospital Cologne, University of Cologne, Kerpener Straße 62, 50937, Cologne, Germany
| | - Jan Borggrefe
- Institute for Diagnostic and Interventional Radiology, Faculty of Medicine and University Hospital Cologne, University of Cologne, Kerpener Straße 62, 50937, Cologne, Germany
| | - Nikhil Ramaiya
- Department of Radiology, University Hospitals Cleveland Medical Center, 11000 Euclid Ave, 44106 Cleveland, OH, USA; Department of Radiology, Case Western Reserve University, 10900 Euclid Ave, 44106, Cleveland, OH, USA
| | - Nils Große Hokamp
- Institute for Diagnostic and Interventional Radiology, Faculty of Medicine and University Hospital Cologne, University of Cologne, Kerpener Straße 62, 50937, Cologne, Germany; Department of Radiology, University Hospitals Cleveland Medical Center, 11000 Euclid Ave, 44106 Cleveland, OH, USA; Department of Radiology, Case Western Reserve University, 10900 Euclid Ave, 44106, Cleveland, OH, USA
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Albrecht MH, Vogl TJ, Martin SS, Nance JW, Duguay TM, Wichmann JL, De Cecco CN, Varga-Szemes A, van Assen M, Tesche C, Schoepf UJ. Review of Clinical Applications for Virtual Monoenergetic Dual-Energy CT. Radiology 2019; 293:260-271. [DOI: 10.1148/radiol.2019182297] [Citation(s) in RCA: 71] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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Kaposi PN, Youn T, Tóth A, Frank VG, Shariati S, Szendrői A, Magyar P, Bérczi V. Orthopaedic metallic artefact reduction algorithm facilitates CT evaluation of the urinary tract after hip prosthesis. Clin Radiol 2019; 75:78.e17-78.e24. [PMID: 31590913 DOI: 10.1016/j.crad.2019.08.027] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Accepted: 08/29/2019] [Indexed: 11/28/2022]
Abstract
AIM To examine the improvement in the visualisation of bladder and ureteric pathologies next to a hip prosthesis with metallic artefact reduction for orthopaedic implants (O-MAR). MATERIALS AND METHODS Thirty-four patients who underwent pelvic computed tomography (CT) for non-prosthesis-related causes were enrolled retrospectively. Portal venous phase scans were reconstructed both with standard iterative reconstruction (ITR) and with O-MAR. The density of the ureters and the bladder was measured at both sides in the plane of the prosthesis. A semi-quantitative score was also used to assess visibility. The R (version 3.4.1) package was used for statistical analysis. RESULTS The average (μ) density of the 41 prosthesis side ureters was significantly lower on ITR images (μ=-94.76±150.48 [±SD] HU) than on O-MAR images (μ=-13.40±36.37 HU; p<0.0004). The difference between the ITR and O-MAR (μ=-138.62±182.64 versus -35.55±40.21 HU; p<0.0003) was also significant at the prosthesis side of the bladder. The visibility of the prosthesis side ureters was improved: 53.7% was obscured on ITR series compared to 4.9% on O-MAR. The visibility score was also better across all levels (p<0.001) with O-MAR. In four cases (13%), the O-MAR images significantly changed the diagnosis: in two cases ureteric stones, in one case each a bladder stone and a bladder tumour were discovered. CONCLUSIONS O-MAR reconstruction of CT images significantly improves the visibility of the urinary tract adjacent to metallic hip implants. Thus, O-MAR is essential for detecting ureteric and bladder pathologies in patients with a hip prosthesis.
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Affiliation(s)
- P N Kaposi
- Department of Radiology, Semmelweis University, Budapest, Hungary.
| | - T Youn
- Department of Radiology, Semmelweis University, Budapest, Hungary
| | - A Tóth
- Department of Radiology, Semmelweis University, Budapest, Hungary
| | - V G Frank
- Department of Radiology, Semmelweis University, Budapest, Hungary
| | - S Shariati
- Department of Radiology, Semmelweis University, Budapest, Hungary
| | - A Szendrői
- Department of Urology, Semmelweis University, Budapest, Hungary
| | - P Magyar
- Department of Radiology, Semmelweis University, Budapest, Hungary
| | - V Bérczi
- Department of Radiology, Semmelweis University, Budapest, Hungary
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Feasibility of Submillisievert CT of the Skeletal Pelvis Using Iterative Reconstruction: A Human Cadaver Study. AJR Am J Roentgenol 2019; 213:903-911. [PMID: 31287726 DOI: 10.2214/ajr.18.20933] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Zeng Y, Deng K, Yang H, Tan Y, Liu J, Geng D, Zhang J. Noise-optimised virtual monoenergetic imaging of dual-energy CT: effect on metal artefact reduction in patients with lumbar internal fixation. 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 2019; 28:1783-1792. [PMID: 31041597 DOI: 10.1007/s00586-019-05984-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Revised: 04/09/2019] [Accepted: 04/19/2019] [Indexed: 10/26/2022]
Abstract
PURPOSE The purpose of this study was to evaluate the effects of noise-optimised virtual monoenergetic imaging (VMI+) reconstructions on reducing metal artefacts compared to traditional virtual monoenergetic imaging (VMI) and linearly blended (M_0.6) reconstructions in patients with lumbar metal internal fixation in dual-energy CT (DECT). METHODS Forty patients who underwent DECT were evaluated in this retrospective study. Images were reconstructed with M_0.6 and with VMI+ and VMI at 10-keV intervals from 40 keV to 190 keV. Attenuation and noise were measured in the hyperdense artefacts, hypodense artefacts, spinal canal, abdominal aorta (AA), and inferior vena cava (IVC). An artefact index (AI) was calculated. A subjective evaluation of the metal-bone interface, surrounding soft tissue, spinal canal, AA, and IVC was conducted. RESULTS The AI values for the hypodense artefacts, spinal canal, and IVC were lowest in the 130 keV VMI+ series, for the hyperdense artefacts in the 120 keV VMI+ series, and for the AA in the 190 keV VMI+ series. Except for the hypodense artefacts, the AI values were lower compared to the M_0.6 images and all the VMI series (all p < 0.05). The subjective image quality was highest at 130 keV VMI+ for the metal-bone interface, surrounding soft tissue, AA, and IVC, and at 120 keV VMI+ for the spinal canal. Except for the AA, these rating scores were higher compared to the M_0.6 images and the entire VMI series (all p < 0.05). CONCLUSIONS DECT with high-keV VMI+ efficiently reduces metal artefacts and shows superior image quality in patients with lumbar internal fixation. These slides can be retrieved from Electronic Supplementary Material.
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Affiliation(s)
- Yanwei Zeng
- Department of Radiology, Huashan Hospital, Fudan University, No.12 Wulumuqi Road (Middle), Shanghai, 200040, China
- Institute of Functional and Molecular Medical Imaging, Fudan University, No.12 Wulumuqi Road (Middle), Shanghai, 200040, China
| | - Kai Deng
- Department of Radiology, Second Xiangya Hospital, Central South University, Changsha, 410011, China
| | - Haitao Yang
- Department of Radiology, Second Xiangya Hospital, Central South University, Changsha, 410011, China
| | - Yi Tan
- Department of Radiology, Second Xiangya Hospital, Central South University, Changsha, 410011, China
| | - Jun Liu
- Department of Radiology, Second Xiangya Hospital, Central South University, Changsha, 410011, China.
| | - Daoying Geng
- Department of Radiology, Huashan Hospital, Fudan University, No.12 Wulumuqi Road (Middle), Shanghai, 200040, China
- Institute of Functional and Molecular Medical Imaging, Fudan University, No.12 Wulumuqi Road (Middle), Shanghai, 200040, China
| | - Jun Zhang
- Department of Radiology, Huashan Hospital, Fudan University, No.12 Wulumuqi Road (Middle), Shanghai, 200040, China.
- Institute of Functional and Molecular Medical Imaging, Fudan University, No.12 Wulumuqi Road (Middle), Shanghai, 200040, China.
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D'Angelo T, Cicero G, Mazziotti S, Ascenti G, Albrecht MH, Martin SS, Othman AE, Vogl TJ, Wichmann JL. Dual energy computed tomography virtual monoenergetic imaging: technique and clinical applications. Br J Radiol 2019; 92:20180546. [PMID: 30919651 DOI: 10.1259/bjr.20180546] [Citation(s) in RCA: 73] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Dual energy CT (DECT) has evolved into a commonly applied imaging technique in clinical routine due to its unique post-processing opportunities for improved evaluation of all body areas. Reconstruction of virtual monoenergetic imaging (VMI) series has shown beneficial effects for both non-contrast and contrast-enhanced DECT due to the flexibility to calculate low-keV VMI reconstructions to increase contrast and iodine attenuation, or to compute high-keV VMI reconstructions to reduce beam-hardening artefacts. The goal of this review article is to explain the technical background of VMI and noise-optimized VMI+ algorithms and to give an overview of useful clinical applications of the VMI technique in DECT of various body regions.
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Affiliation(s)
- Tommaso D'Angelo
- 1 Department of Biomedical Sciences and Morphological and Functional Imaging, Policlinico G. Martino - University Hospital Messina , Messina , Italy.,2 Department of Diagnostic and Interventional Radiology, Division of Experimental Imaging, University Hospital Frankfurt , Frankfurt , Germany
| | - Giuseppe Cicero
- 1 Department of Biomedical Sciences and Morphological and Functional Imaging, Policlinico G. Martino - University Hospital Messina , Messina , Italy
| | - Silvio Mazziotti
- 1 Department of Biomedical Sciences and Morphological and Functional Imaging, Policlinico G. Martino - University Hospital Messina , Messina , Italy
| | - Giorgio Ascenti
- 1 Department of Biomedical Sciences and Morphological and Functional Imaging, Policlinico G. Martino - University Hospital Messina , Messina , Italy
| | - Moritz H Albrecht
- 2 Department of Diagnostic and Interventional Radiology, Division of Experimental Imaging, University Hospital Frankfurt , Frankfurt , Germany
| | - Simon S Martin
- 2 Department of Diagnostic and Interventional Radiology, Division of Experimental Imaging, University Hospital Frankfurt , Frankfurt , Germany
| | - Ahmed E Othman
- 3 Department of Diagnostic and Interventional Radiology, Eberhard Karls University Tübingen , Tübingen , Germany
| | - Thomas J Vogl
- 2 Department of Diagnostic and Interventional Radiology, Division of Experimental Imaging, University Hospital Frankfurt , Frankfurt , Germany
| | - Julian L Wichmann
- 2 Department of Diagnostic and Interventional Radiology, Division of Experimental Imaging, University Hospital Frankfurt , Frankfurt , Germany
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Metal artifacts in patients with large dental implants and bridges: combination of metal artifact reduction algorithms and virtual monoenergetic images provides an approach to handle even strongest artifacts. Eur Radiol 2019; 29:4228-4238. [PMID: 30649598 DOI: 10.1007/s00330-018-5928-7] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Revised: 11/06/2018] [Accepted: 11/28/2018] [Indexed: 10/27/2022]
Abstract
OBJECTIVES This study compares reduction of strong metal artifacts from large dental implants/bridges using spectral detector CT-derived virtual monoenergetic images (VMI), metal artifact reduction algorithms/reconstructions (MAR), and a combination of both methods (VMIMAR) to conventional CT images (CI). METHODS Forty-one spectral detector CT (SDCT) datasets of patients that obtained additional MAR reconstructions due to strongest artifacts from large oral implants were included. CI, VMI, MAR, and VMIMAR ranging from 70 to 200 keV (10 keV increment) were reconstructed. Objective image analyses were performed ROI-based by measurement of attenuation (HU) and standard deviation in most pronounced hypo-/hyperdense artifacts as well as artifact impaired soft tissue (mouth floor/soft palate). Extent of artifact reduction, diagnostic assessment of soft tissue, and appearance of new artifacts were rated visually by two radiologists. RESULTS The hypo-/hyperattenuating artifacts showed an increase and decrease of HU values in MAR and VMIMAR (CI/MAR/VMIMAR-200keV: - 369.8 ± 239.6/- 37.3 ± 109.6/- 46.2 ± 71.0 HU, p < 0.001 and 274.8 ± 170.2/51.3 ± 150.8/36.6 ± 56.0, p < 0.001, respectively). Higher keV values in hyperdense artifacts allowed for additional artifact reduction; however, this trend was not significant. Artifacts in soft tissue were reduced significantly by MAR and VMIMAR. Visually, high-keV VMI, MAR, and VMIMAR reduced artifacts and improved diagnostic assessment of soft tissue. Overcorrection/new artifacts were reported that mostly did not hamper diagnostic assessment. Overall interrater agreement was excellent (ICC = 0.85). CONCLUSIONS In the presence of strong artifacts due to large oral implants, MAR is a powerful mean for artifact reduction. For hyperdense artifacts, MAR should be supplemented by VMI ranging from 140 to 200 keV. This combination yields optimal artifact reduction and improves the diagnostic image assessment in imaging of the head and neck. KEY POINTS • Large oral implants can cause strong artifacts. • MAR is a powerful tool for artifact reduction considering such strong artifacts. • Hyperdense artifact reduction is supplemented by VMI of 140-200 keV from SDCT.
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Metal Artifact Reduction in Routine Chest and Abdominal Examinations Using Virtual Monoenergetic Images From Spectral Detector Computed Tomography. J Comput Assist Tomogr 2019; 43:713-717. [DOI: 10.1097/rct.0000000000000901] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Clinical Assessment of Metal Artifact Reduction Methods in Dual-Energy CT Examinations of Instrumented Spines. AJR Am J Roentgenol 2018; 212:395-401. [PMID: 30667317 DOI: 10.2214/ajr.18.19757] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
OBJECTIVE The purpose of this study was to evaluate the performance of three metal artifact reduction methods in dual-energy CT (DECT) examinations of instrumented spines. MATERIALS AND METHODS Twenty patients with instrumented spines who underwent spine DECT were retrospectively identified. All scans were obtained on a dual-source 128-MDCT scanner. In addition to the original DE mixed images, DECT images were reconstructed using an iterative metal artifact reconstruction algorithm (DE iMAR), virtual monochromatic imaging (VMI) algorithm (DE Mono+), and a combination of the two algorithms DE iMAR and DE Mono+, which we refer to here as "DE iMAR Mono+." The four image series were anonymized and randomized for a reader study. Four experienced neuroradiologists rated the images in terms of artifact scores of four anatomic regions and overall image quality scores in both bone and soft-tissue display window settings. In addition, a quantitative analysis was performed to assess the performance of the three metal artifact reduction methods. RESULTS There were statistically significant differences in the artifact scores and overall image quality scores among the four methods (both, p < 0.001). DE iMAR Mono+ showed the best artifact scores and quality scores (all, p < 0.001). The intraclass correlation coefficient for the overall image quality score was 0.779 using the bone display window and 0.892 using the soft-tissue display window (both, p < 0.001). In addition, DE iMAR Mono+ reduced the artifacts by the greatest amount in the quantitative analysis. CONCLUSION The method that used DE iMAR Mono+ showed the best performance of spine metal artifact reduction using DECT data. These results may be specific to this CT vendor and implant type.
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Virtual Monoenergetic Images for Diagnostic Assessment of Hypodense Lesions Within the Liver: Semiautomatic Estimation of Window Settings Using Linear Models. J Comput Assist Tomogr 2018; 42:925-931. [PMID: 30371610 DOI: 10.1097/rct.0000000000000794] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
OBJECTIVE The aim of the study was to establish the reference window settings for display of virtual monoenergetic images (VMIs) from spectral detector computed tomography when assessing hypodense liver lesions. METHODS In patients with cysts (n = 24) or metastases (n = 26), objective (HU, signal-to-noise ratio [SNR]) and subjective (overall image quality, lesion conspicuity and noise) were assessed. Furthermore, 2 readers determined optimal window center/width (C/W) for conventional images (CIs) and VMIs of 40 to 120 keV. Center/width were modeled against HUliv with and without respect to the keV level (models A and B). RESULTS Attenuation and SNR were significantly higher in low-keV VMIs and improved overall image quality and lesion conspicuity (P ≤ 0.05). Model B provided valid estimations of C/W, whereas model A was slightly less accurate. CONCLUSIONS The increase in attenuation and SNR on low-keV VMIs requires adjustment of C/W, and they can be estimated in dependency of HUliv using linear models. Reference values for standard display of VMIs of 40 to 120 keV are reported.
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Improved visualization of hypodense liver lesions in virtual monoenergetic images from spectral detector CT: Proof of concept in a 3D-printed phantom and evaluation in 74 patients. Eur J Radiol 2018; 109:114-123. [PMID: 30527292 DOI: 10.1016/j.ejrad.2018.11.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Revised: 09/29/2018] [Accepted: 11/02/2018] [Indexed: 11/23/2022]
Abstract
OBJECTIVES The well-known boost of iodine associated-attenuation in low-keV virtual monoenergetic images (VMI_low) is frequently used to improve visualization of lesions and structures taking up contrast media. This study aimed to evaluate this concept in reverse. Hence to investigate if increased attenuation within the liver allows for improved visualization of little or not-enhancing lesions. METHODS A 3D-printed phantom mimicking the shape of a human liver exhibiting a lesion in its center was designed and printed. Both, parenchyma- and lesion-mimic were filled with different solutions exhibiting 80/100/120HU and 0/15/40/60HU, respectively. Further, a total of 74 contrast-enhanced studies performed on a spectral detector CT scanner (SDCT) were included in this retrospective study. Patients had MRI or follow-up proven cysts and/or hypodense metastases. VMI of 40-200 keV as well as conventional images (CI) were reconstructed. ROI were placed in lesion and parenchyma(-mimics) on CI and transferred to VMI. Signal- and contrast-to-noise ratio were calculated (S-/CNR). Further, two radiologists independently evaluated image quality. Data was statistically assessed using ANOVA or Wilcoxon-test. RESULTS In phantoms, S/CNR was significantly higher in VMI_low. The cyst-mimic in highly attenuating parenchyma-mimic on CI yielded a CNR of 6.4 ± 0.8; using VMI_40 keV, mildly hypodense lesion-mimic in poorly attenuating parenchyma-mimic exhibited a similar CNR (5.8 ± 0.9; p ≤ 0.05). The same tendency was observed in patients (cyst in CI/metastasis in VMI_40 keV: 4.4 ± 1.2/3.9 ± 1.8; p ≤ 0.05). Qualitative analysis indicated a benefit of VMI_40 keV (p ≤ 0.05). CONCLUSIONS VMI_low from SDCT allow for an improved visualization of hypodense focal liver lesions exploiting the concept of contrast blooming in reverse.
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Wellenberg RHH, Hakvoort ET, Slump CH, Boomsma MF, Maas M, Streekstra GJ. Metal artifact reduction techniques in musculoskeletal CT-imaging. Eur J Radiol 2018; 107:60-69. [PMID: 30292274 DOI: 10.1016/j.ejrad.2018.08.010] [Citation(s) in RCA: 81] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Revised: 07/02/2018] [Accepted: 08/11/2018] [Indexed: 01/02/2023]
Abstract
It is known that metal artifacts can be reduced by modifying standard acquisition and reconstruction, by modifying projection data and/or image data and by using virtual monochromatic imaging extracted from dual-energy CT. In this review we focus on the origin of metal artifacts, technical background of commercially available metal artifact reduction (MAR) algorithms and the value of dual-energy CT and MAR software for different metal hardware in current clinical practice. Virtual monochromatic imaging reduces beam-hardening artifacts, where metal artifact reduction software effectively reduces artifacts caused by extensive photon-starvation. Both techniques have their advantages and disadvantages, and the combination of both techniques is often but not always the best solution regarding metal artifact reduction. Advances in prosthetic imaging are reinforced by advances in prosthetic design. Providing implant specific information prior to scanning is important in order to adjust the metal artifact reduction approach, minimize artifacts and optimize image quality and diagnostic value of CT.
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Affiliation(s)
- R H H Wellenberg
- Department of Radiology and Nuclear Medicine, Amsterdam University Medical Center, location AMC, University of Amsterdam, Amsterdam Movement Sciences, Amsterdam, The Netherlands; Department of Radiology, Isala, Zwolle, The Netherlands.
| | - E T Hakvoort
- Department of Biomedical Engineering and Physics, Amsterdam University Medical Center, location AMC, Amsterdam, The Netherlands.
| | - C H Slump
- MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede, The Netherlands.
| | - M F Boomsma
- Department of Radiology, Isala, Zwolle, The Netherlands.
| | - M Maas
- Department of Radiology and Nuclear Medicine, Amsterdam University Medical Center, location AMC, University of Amsterdam, Amsterdam Movement Sciences, Amsterdam, The Netherlands.
| | - G J Streekstra
- Department of Biomedical Engineering and Physics, Amsterdam University Medical Center, location AMC, Amsterdam, The Netherlands.
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Große Hokamp N, Laukamp K, Lennartz S, Zopfs D, Abdullayev N, Neuhaus V, Maintz D, Borggrefe J. Artifact reduction from dental implants using virtual monoenergetic reconstructions from novel spectral detector CT. Eur J Radiol 2018; 104:136-142. [DOI: 10.1016/j.ejrad.2018.04.018] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2017] [Revised: 03/31/2018] [Accepted: 04/18/2018] [Indexed: 11/27/2022]
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Reduction of Artifacts Caused by Deep Brain Stimulating Electrodes in Cranial Computed Tomography Imaging by Means of Virtual Monoenergetic Images, Metal Artifact Reduction Algorithms, and Their Combination. Invest Radiol 2018; 53:424-431. [DOI: 10.1097/rli.0000000000000460] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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