Combining gantry-free cone-beam computed tomography with iterative metal artefact reduction for surgical follow-up imaging of the appendicular skeleton

Patzer, Theresa Sophie; Grunz, Jan-Peter; Huflage, Henner; Conrads, Nora; Veldhoen, Simon; Schmalzl, Jonas; Pennig, Lenhard; Bley, Thorsten Alexander; Luetkens, Karsten Sebastian; Kunz, Andreas Steven

doi:10.1016/j.ejrad.2022.110465

Cited by 7 publications

(7 citation statements)

References 27 publications

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“…Other previous studies have also investigated the benefit of the intrinsic spectral resolution of PCD-CDs in reducing metal artifacts in dedicated clinical body regions. [30][31][32][33][34][35][36] Another limitation within this study is the lack of the incorporation of spectral information into the MAR pipeline, which has been shown to be beneficial for individual components of MAR. 37,38 As the framework of this work is also intended to be applied to conventional EID-CTs, where spectral resolution is only available in dual-energy protocols on dual-source CTs 29,39,40 or by performing a dual-spiral scan, this has not been incorporated within this work, but current research is focused on embedding spectral information within the applied framework.…”

Section: Discussion and Outlookmentioning

confidence: 99%

“…As our previous study with different phantoms demonstrated, the energetic resolution of this scanner can further reduce the strength of metallic objects in certain low-attenuating metal implant types, 23 but the additional variation of the energy within the images would have been beyond the scope of this work. Other previous studies have also investigated the benefit of the intrinsic spectral resolution of PCD-CDs in reducing metal artifacts in dedicated clinical body regions 30–36 . Another limitation within this study is the lack of the incorporation of spectral information into the MAR pipeline, which has been shown to be beneficial for individual components of MAR 37,38 .…”

Section: Discussion and Outlookmentioning

confidence: 99%

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A New Iterative Metal Artifact Reduction Algorithm for Both Energy-Integrating and Photon-Counting CT Systems

Anhaus,

Heider,

Killermann

et al. 2024

Invest Radiol

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Objectives The aim of this study was to introduce and evaluate a new metal artifact reduction framework (iMARv2) that addresses the drawbacks (residual artifacts after correction and user preferences for image quality) associated with the current clinically applied iMAR. Materials and Methods A new iMARv2 has been introduced, combining the current iMAR with new modular components to remove residual metal artifacts after image correction. The postcorrection image impression is adjustable with user-selectable strength settings. Phantom scans from an energy-integrating and a photon-counting detector CT were used to assess image quality, including a Gammex phantom and anthropomorphic phantoms. In addition, 36 clinical cases (with metallic implants such as dental fillings, hip replacements, and spinal screws) were reconstructed and evaluated in a blinded and randomized reader study. Results The Gammex phantom showed lower HU errors compared with the uncorrected image at almost all iMAR and iMARv2 settings evaluated, with only minor differences between iMAR and the different iMARv2 settings. In addition, the anthropomorphic phantoms showed a trend toward lower errors with higher iMARv2 strength settings. On average, the iMARv2 strength 3 performed best of all the clinical reconstructions evaluated, with a significant increase in diagnostic confidence and decrease in artifacts. All hip and dental cases showed a significant increase in diagnostic confidence and decrease in artifact strength, and the improvements from iMARv2 in the dental cases were significant compared with iMAR. There were no significant improvements in the spine. Conclusions This work has introduced and evaluated a new method for metal artifact reduction and demonstrated its utility in routine clinical datasets. The greatest improvements were seen in dental fillings, where iMARv2 significantly improved image quality compared with conventional iMAR.

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Section: Discussion and Outlookmentioning

confidence: 99%

Section: Discussion and Outlookmentioning

confidence: 99%

A New Iterative Metal Artifact Reduction Algorithm for Both Energy-Integrating and Photon-Counting CT Systems

Anhaus,

Heider,

Killermann

et al. 2024

Invest Radiol

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“…Other PCD CT studies examining the impact of VMI on hip implants and dental implants have shown that VMI alone is not effective in reducing metal artifacts but instead requires the additional use of iterative Metal Artifact Reduction (iMAR) algorithms for substantial artifact reduction. 14,20 The reduced efficacy of VMIs in these implants may be explained by the increased baseline artifact level for polychromatic CT scans without spectral shaping, as tin prefiltration removes low-energy photons, which are known to contribute significantly to beam hardening artifacts. 6 The second reason for these seemingly conflicting results compared with our study may be that the artifacts depend on the implant geometry and atomic number of the implanted material, as stated previously.…”

Section: Discussionmentioning

confidence: 99%

“…1), as previously reported by other authors. 14,15 All ROIs were placed on polychromatic images and then copied to the identical position on VMIs of different energy levels. To achieve a high level of measurement accuracy, ROIs on polychromatic images were placed on 3 consecutive CT slices.…”

Section: Quantitative Image Analysismentioning

confidence: 99%

Photon-Counting Detector CT

Marth,

Goller,

Kajdi

et al. 2024

Invest Radiol

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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 (VMISn and VMIStd, 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 VMISn ≥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 VMIStd, 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, VMISn 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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“…It is very common, and it often limits the assessment of cervical structures or structures in the brain. Other clinical studies also suggested the combination of IMAR and VMI for metal artifact reduction in the hip [89] and for dental implants [90].…”

Section: Metal Artifact Reductionmentioning

confidence: 99%

Photon-counting detector CT – first experiences in the field of musculoskeletal radiology

Bette,

Risch,

Becker

et al. 2024

Rofo

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The introduction of photon-counting detector CT (PCD-CT) marks a remarkable leap in innovation in CT imaging. The new detector technology allows X-rays to be converted directly into an electrical signal without an intermediate step via a scintillation layer and allows the energy of individual photons to be measured. Initial data show high spatial resolution, complete elimination of electronic noise, and steady availability of spectral image data sets. In particular, the new technology shows promise with respect to the imaging of osseous structures. Recently, PCD-CT was implemented in the clinical routine. The aim of this review was to summarize recent studies and to show our first experiences with photon-counting detector technology in the field of musculoskeletal radiology.We performed a literature search using Medline and included a total of 90 articles and reviews that covered recent experimental and clinical experiences with the new technology.In this review, we focus on (1) spatial resolution and delineation of fine anatomic structures, (2) reduction of radiation dose, (3) electronic noise, (4) techniques for metal artifact reduction, and (5) possibilities of spectral imaging. This article provides insight into our first experiences with photon-counting detector technology and shows results and images from experimental and clinical studies.Bette S, Risch F, Becker J et al. Photon-counting detector CT – first experiences in the field of musculoskeletal radiology. Fortschr Röntgenstr 2024; DOI 10.1055/a-2312-6914

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Combining gantry-free cone-beam computed tomography with iterative metal artefact reduction for surgical follow-up imaging of the appendicular skeleton

Cited by 7 publications

References 27 publications

A New Iterative Metal Artifact Reduction Algorithm for Both Energy-Integrating and Photon-Counting CT Systems

A New Iterative Metal Artifact Reduction Algorithm for Both Energy-Integrating and Photon-Counting CT Systems

Photon-Counting Detector CT

Photon-counting detector CT – first experiences in the field of musculoskeletal radiology

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