Metal artifacts reduction using monochromatic images from spectral CT: Evaluation of pedicle screws in patients with scoliosis

Yang, Wang; Qian, Bangping; Li, Baoxin; Guochu, Qin; Zhou, Zhengyang; Qiu, Yong; Sun, Xu; Zhu, Bin

doi:10.1016/j.ejrad.2013.02.024

Cited by 125 publications

(116 citation statements)

References 23 publications

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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%

“…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. Additionally, prior studies have not systematically assessed how metal artifact reduction images should be incorporated into clinical practice (eg, instead of or in addition to routine images).…”

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confidence: 99%

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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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Section: Discussionmentioning

confidence: 99%

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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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“…Since the application of ASIR usually reduces image noise, the combinational use 84 of GSI and ASIR may further improve the quality of CT images for evaluating post-spinal fusion 85 patients. However, prior studies about metal artifact reduction with GSI mainly focused on the 86 application of GSI technology alone Wang et al, 2013). We believe this study 87 is the first to investigate the combined effectiveness of GSI and ASIR in post spinal fusion CT 88 imaging.…”

mentioning

confidence: 91%

“…65 66 There are technologies developed to reduce the image artifacts from metal implants. Among 67 the artifact-reducing approaches, monochromatic imaging generated by gemstone spectral 68 imaging (GSI) dual-energy CT has been extensively studied and shown of value for effectively 69 reducing metal artifacts Wang et al, 2013). There are, however, limitations of 70 images produced by GSI technology.…”

Section: Introductionmentioning

confidence: 99%

“…We 114 chose the photon energy level of 110 keV to represent GSI images, as this level has been well 115 demonstrated to be the most effective photon energy level to reduce metal artifacts by previous 116 researches (Meinel et al, 2012;Wang et al, 2013). For every single patient, 5 sets of images 117 were generated and transferred to a commercial workstation (GE VolumeShare ADW4.6, GE 118 Healthcare).…”

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Supplemental Information 1: Raw Data of Subjective and Objective Image Quality Assessment

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Objective. To explore whether the image noises and the metal artifacts could be further managed by the combined use of two technologies, the adaptive statistical iterative reconstruction (ASIR) and the monochromatic imaging generated by gemstone spectral imaging (GSI) dual-energy CT. Materials and Methods. Fifty-one patients with 318 spinal pedicle screws were prospectively scanned with dual energy CT by using fast kV-switching GSI between 80 and 140 kVp. The monochromatic GSI images at 110 keV were reconstructed either without ASIR or with ASIR of various levels (30%, 50%, 70% and 100%). For these five sets of images, both objective and subjective image quality assessments were performed to evaluate the image quality. Results. With objective image quality assessment, the metal artifacts (measured by an artifacts index) significantly decreased when increasing levels of ASIR was utilized (p < 0.001). Moreover, adding ASIR to GSI also decreased the image noise (p < 0.001) and improved the signalto-noise ratio (SNR, p < 0.001). With subjective image quality analysis, the inter-reader agreements were good, with intra-class correlation coefficients (ICC) of 0.89 to 0.99.Meanwhile, the visualization of the peri-implant soft tissue was improved at higher ASIR levels (p < 0.001). Conclusion. Combined use of ASIR and GSI is shown to decrease the image noise and improve the image quality in post-spinal fusion CT scans. Optimal results were achieved with ASIR levels of over 70%.PeerJ PrePrints | https://dx.doi.org/10.7287/peerj.preprints.1306v1 | CC-BY 4.0 Open Access |

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Imaging‐based biomarkers: Changes in the tumor interface of pancreatic ductal adenocarcinoma on computed tomography scans indicate response to cytotoxic therapy

Amer

Zaid

Chaudhury

et al. 2018

Cancer

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BACKGROUNDThe assessment of pancreatic ductal adenocarcinoma (PDAC) response to therapy remains challenging. The objective of this study was to investigate whether changes in the tumor/parenchyma interface are associated with response.METHODSComputed tomography (CT) scans before and after therapy were reviewed in 4 cohorts: cohort 1 (99 patients with stage I/II PDAC who received neoadjuvant chemoradiation and surgery); cohort 2 (86 patients with stage IV PDAC who received chemotherapy), cohort 3 (94 patients with stage I/II PDAC who received protocol‐based neoadjuvant gemcitabine chemoradiation), and cohort 4 (47 patients with stage I/II PDAC who received neoadjuvant chemoradiation and were prospectively followed in a registry). The tumor/parenchyma interface was visually classified as either a type I response (the interface remained or became well defined) or a type II response (the interface became poorly defined) after therapy. Consensus (cohorts 1‐3) and individual (cohort 4) visual scoring was performed. Changes in enhancement at the interface were quantified using a proprietary platform.RESULTSIn cohort 1, type I responders had a greater probability of achieving a complete or near‐complete pathologic response (21% vs 0%; P = .01). For cohorts 1, 2, and 3, type I responders had significantly longer disease‐free and overall survival, independent of traditional covariates of outcomes and of baseline and normalized cancer antigen 19‐9 levels. In cohort 4, 2 senior radiologists achieved a κ value of 0.8, and the interface score was associated with overall survival. The quantitative method revealed high specificity and sensitivity in classifying patients as type I or type II responders (with an area under the receiver operating curve of 0.92 in cohort 1, 0.96 in cohort 2, and 0.89 in cohort 3).CONCLUSIONSChanges at the PDAC/parenchyma interface may serve as an early predictor of response to therapy. Cancer 2018;124:1701‐9. © 2018 The Authors. Cancer published by Wiley Periodicals, Inc. on behalf of American Cancer Society. This is an open access article under the terms of the Creative Commons Attribution‐NonCommercial‐NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non‐commercial and no modifications or adaptations are made.

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Metal artifacts reduction using monochromatic images from spectral CT: Evaluation of pedicle screws in patients with scoliosis

Cited by 125 publications

References 23 publications

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

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

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Imaging‐based biomarkers: Changes in the tumor interface of pancreatic ductal adenocarcinoma on computed tomography scans indicate response to cytotoxic therapy

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