Metal Artifact Reduction by Dual-Energy Computed Tomography Using Energetic Extrapolation

Meinel, Felix G.; Bischoff, Bernhard; Zhang, Qiaowei; Bamberg, Fabian; Reiser, Maximilian; Johnson, Thorsten R. C.

doi:10.1097/rli.0b013e31824c86a3

Cited by 164 publications

(123 citation statements)

References 26 publications

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“…A DECT protocol optimization study by Meinel et al 6 showed that optimal MAR was seen when using a monoenergetic level of between 105 and 120 keV. Recommendations from application specialists from the different CT scanner vendors and from radiologists in the hospital's clinic reasonably coincided with this conclusion.…”

Section: Phantom Imagingmentioning

confidence: 88%

“…This application makes it possible to obtain images as though they had been acquired with a monoenergetic high-energy beam, which would lead to reduction of metal artefacts caused by beam hardening. [5][6][7][8][9] In addition to monoenergetic reconstructions in DECT, dedicated MAR algorithms have become available for clinical practice in the past couple of years. MAR algorithms in both single-energy CT imaging [10][11][12][13][14] and DECT imaging 8,9 have been shown to reduce metal artefacts.…”

mentioning

confidence: 99%

“…[5][6][7][8][9][10][11][12][13] Monoenergetic images, reconstructed from DECT data, have been shown to enhance the diagnostic value of CT images containing orthopaedic implants. [5][6][7][8][9][10] Li et al 12 studied the application of a commercially available MAR algorithm in radiotherapy treatment planning and concluded that it improved CT number accuracy and structure visualization in CT images of orthopaedic implants. However, the improvement in CT number accuracy was shown not to have any significant clinical impact on photon dose calculations.…”

mentioning

confidence: 99%

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Metal artefact reduction in CT imaging of hip prostheses—an evaluation of commercial techniques provided by four vendors

Andersson¹,

Nowik²,

Persliden³

et al. 2015

BJR

108

106

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Objective: The aim of this study was to evaluate commercial metal artefact reduction (MAR) techniques in X-ray CT imaging of hip prostheses. Methods: Monoenergetic reconstructions of dual-energy CT (DECT) data and several different MAR algorithms, combined with single-energy CT or DECT, were evaluated by imaging a bilateral hip prosthesis phantom. The MAR images were compared with uncorrected images based on CT number accuracy and noise in different regions of interest. Results: The three MAR algorithms studied implied a general noise reduction (up to 67%, 74% and 77%) and an improvement in CT number accuracy, both in regions close to the prostheses and between the two prostheses. The application of monoenergetic reconstruction, without any MAR algorithm, did not decrease the noise in the regions close to the prostheses to the same extent as did the MAR algorithms and even increased the noise in the region between the prostheses. Conclusion: The MAR algorithms evaluated generally improved CT number accuracy and substantially reduced the noise in the hip prostheses phantom images, both close to the prostheses and between the two prostheses. The study showed that the monoenergetic reconstructions evaluated did not sufficiently reduce the severe metal artefact caused by large orthopaedic implants. Advances in knowledge: This study evaluates several commercially available MAR techniques in CT imaging of large orthopaedic implants.Images degraded by metal artefacts are a common problem in X-ray CT imaging. Artefacts caused by the presence of metallic implants in the CT scanned volume, such as hip prostheses or dental fillings, appear as dark and bright streaks across the reconstructed image. Metal artefacts can severely degrade the image quality and hence limit the diagnostic value of a CT scan. 1 Hip prostheses cause severe artefacts when present in a CT scanned volume, and the resulting degradation of image quality leads to difficulties in diagnosing fractures, implant loosening or pathology in organs or soft tissue in the pelvic area. If CT images containing hip prostheses are used in radiotherapy treatment planning for tissue heterogeneity correction, the metal artefacts may introduce inaccuracies in dose calculations.Metal artefacts in CT imaging are mainly caused by beam hardening and photon starvation. Photon starvation artefacts are created when X-rays traverse materials with high attenuation coefficients, which leads to an insufficient amount of photons reaching the detectors and results in very noisy projections. The noise is magnified in the reconstruction process and the resulting streaks can be seen in the reconstructed image. Beam hardening refers to the fact that low-energy photons are attenuated to a greater degree than high-energy photons when passing through the scanned volume. This effect is more pronounced when the X-ray beam passes through high-density materials such as metals.

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Section: Phantom Imagingmentioning

confidence: 88%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Metal artefact reduction in CT imaging of hip prostheses—an evaluation of commercial techniques provided by four vendors

Andersson¹,

Nowik²,

Persliden³

et al. 2015

BJR

108

106

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“…7,14 However, the effectiveness of artifact reduction by using monoenergetic imaging appears to be dependent on implant material and size. 7,9,12,13 Our work used a method for metal artifact reduction that can be employed using conventional single-energy CT acquisition with thresholds and other settings potentially altered to adjust for different types and location of metal implants. Others have previously described a 1D linear interpolation to improve CT sinogram data, 15,16 but such approaches have not been put into clinical practice until recently, primarily due to the high computational time requirements.…”

Section: Discussionmentioning

confidence: 99%

“…5,6 On CT, beam-hardening and photon starvation artifacts from metallic fusion hardware frequently compromise visualization of critical anatomic structures and pathologic findings, particularly in the ROI near implanted hardware. Recent publications have presented several postprocessing methods for decreasing the severity of metal implant artifacts in CT. [7][8][9][10][11] These works describe unique challenges to minimizing metal-related artifacts in different body regions due to differences in local anatomy and in implant composition. 12 However, only a few of these works focused on the unique challenges of the postoperative spine, 12,13 and none assessed visualization of the critical anatomic structures that the neuroradiologist must evaluate in the postoperative setting.…”

mentioning

confidence: 99%

CT Metal Artifact Reduction in the Spine: Can an Iterative Reconstruction Technique Improve Visualization?

Kotsenas

Michalak

DeLone

et al. 2015

AJNR Am J Neuroradiol

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An additional tilted‐scan‐based CT metal‐artifact‐reduction method for radiation therapy planning

Kim

Pua

Lee

et al. 2018

J Applied Clin Med Phys

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PurposeAs computed tomography (CT) imaging is the most commonly used modality for treatment planning in radiation therapy, metal artifacts in the planning CT images may complicate the target delineation and reduce the dose calculation accuracy. Although current CT scanners do provide certain correction steps, it is a common understanding that there is not a universal solution yet to the metal artifact reduction (MAR) in general. Particularly noting the importance of MAR for radiation treatment planning, we propose a novel MAR method in this work that recruits an additional tilted CT scan and synthesizes nearly metal‐artifact‐free CT images.MethodsThe proposed method is based on the facts that the most pronounced metal artifacts in CT images show up along the x‐ray beam direction traversing multiple metallic objects and that a tilted CT scan can provide complementary information free of such metal artifacts in the earlier scan. Although the tilted CT scan would contain its own metal artifacts in the images, the artifacts may manifest in a different fashion leaving a chance to concatenate the two CT images with the metal artifacts much suppressed. We developed an image processing technique that uses the structural similarity (SSIM) for suppressing the metal artifacts. On top of the additional scan, we proposed to use an existing MAR method for each scan if necessary to further suppress the metal artifacts.ResultsThe proposed method was validated by a simulation study using the pelvic region of an XCAT numerical phantom and also by an experimental study using the head part of the Rando phantom. The proposed method was found to effectively reduce the metal artifacts. Quantitative analyses revealed that the proposed method reduced the mean absolute percentages of the error by up to 86% and 89% in the simulation and experimental studies, respectively.ConclusionsIt was confirmed that the proposed method, using complementary information acquired from an additional tilted CT scan, can provide nearly metal‐artifact‐free images for the treatment planning.

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Metal Artifact Reduction by Dual-Energy Computed Tomography Using Energetic Extrapolation

Cited by 164 publications

References 26 publications

Metal artefact reduction in CT imaging of hip prostheses—an evaluation of commercial techniques provided by four vendors

Metal artefact reduction in CT imaging of hip prostheses—an evaluation of commercial techniques provided by four vendors

CT Metal Artifact Reduction in the Spine: Can an Iterative Reconstruction Technique Improve Visualization?

An additional tilted‐scan‐based CT metal‐artifact‐reduction method for radiation therapy planning

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