Comparison of Metal Artefacts for Different Dual Energy Ct Techniques

Pettersson, Erik; Bäck, Anna; Thilander-Klang, Anne

doi:10.1093/rpd/ncab105

Cited by 5 publications

(5 citation statements)

References 20 publications

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“…This seems to be different from dual-source and dual-layer spectral-detector CT. Similarly to the findings in rapid-kVp-switching DECT and other studies [ 47 , 48 ], overcorrection of artifact was also observed in spinal implants in our study when using iMAR, however to a much lesser degree. This may be because the iMAR algorithm, used in this study, combines beam hardening correction, normalized sinogram inpainting and frequency split, to address both, the avoidance of new artifacts and the conservation of the original image impression [ 5 , 49 ].…”

Section: Discussionsupporting

confidence: 92%

Metal implants on abdominal CT: does split-filter dual-energy CT provide additional value over iterative metal artifact reduction?

et al. 2022

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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. Graphical abstract

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Section: Discussionsupporting

confidence: 92%

Metal implants on abdominal CT: does split-filter dual-energy CT provide additional value over iterative metal artifact reduction?

et al. 2022

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“…During the evaluation process, we found that MAR technology could reduce beam hardening artifacts for the surrounding structures while causing certain distortion on screw itself, which is consistent with previous research results ( 12 , 27 , 29 ). Some scholars believed that this distortion of MAR could affect the judgment of screws and recommended to use a 140 keV monochromatic images in dual energy CT without the use of MAR when evaluating the metal screws.…”

Section: Discussionsupporting

confidence: 90%

“…Therefore, reducing the beam hardening artifacts of pedicle screws can better evaluate the condition of the bone and soft tissue around the metal screws, helping orthopedic doctors and radiologists to make more accurate evaluations of the surgical effect and condition ( 9 - 11 ). At present, the commonly used methods for removing metal beam hardening artifacts often rely on the use of high energy photons with either high tube voltage or high energy virtual monoenergetic images in dual-energy CT ( 12 - 14 ), or the combination of metal artifact reduction (MAR) technology with reconstruction algorithms to further significantly reduce beam hardening artifacts and improve diagnostic effectiveness ( 15 - 18 ). However, in order to generate adequate signal when taking images of metals, radiation dose is usually relatively high.…”

Section: Introductionmentioning

confidence: 99%

Application of metal artifact reduction algorithm in reducing metal artifacts in post-surgery pediatric low radiation dose spine computed tomography (CT) images

Sun,

Li,

et al. 2024

Quant Imaging Med Surg

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Background The commonly used methods for removing metal-induced beam hardening artifacts often rely on the use of high energy photons with either high tube voltage or high energy virtual monoenergetic images in dual-energy computed tomography (CT), the radiation dose was usually relatively high in order to generate adequate signals. This retrospective study is designed to evaluate the application of a metal artifact reduction (MAR) algorithm in reducing pedicle screw metal-caused beam hardening artifacts in post-surgery pediatric low radiation dose spine CT images. Methods Seventy-seven children (3–15 years) who had undergone a low dose CT with 140 or 100 kV were enrolled. The radiation dose was 1.40 mGy for the 3–8 years old and 2.61 mGy for 9–15 years old children. There were 116 pedicle screws evaluated. The raw data were reconstructed with adaptive statistical iterative reconstruction-V (ASIR-V) at 50% strength, ASIR-V with MAR (AV-MAR), deep learning image reconstruction (DLIR) at high strength and DLIR with MAR (DL-MAR). The image quality concerning pedicle screws was evaluated objectively in terms of the length of beam-hardening artifact (LHA) and artifact index (AI), and subjectively using a 4-point scale (4 points: best, 3 points: acceptable). Results Both AV-MAR and DL-MAR significantly reduced metal-induced beam hardening artifacts with smaller LHA (15.76±10.12 mm, a reduction of 57.24% and 15.66±10.49 mm, a reduction of 57.40%, respectively), and AI value (62.50±33.51, a reduction of 64.65% and 61.03±32.61, a reduction of 65.01%, respectively) compared to ASIR-V and DLIR (all P<0.01), The subjective image quality scores concerning the screws were 3.37±0.49 and 3.47±0.50 with AV-MAR and DL-MAR, respectively, higher than the respective value of 1.73±0.44 and 1.76±0.43 without MAR (all P<0.01). Conclusions MAR significantly reduces the low-density artifacts caused by metal screws in post-surgery pediatric low-dose spine CT images, across different tube voltages, radiation dose levels and reconstruction algorithms. Combining DL-MAR further improves the overall image quality under low radiation dose conditions.

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“…is not yet fully understood and is under active investigation. A possible alternative solution would be dual-energy CT, which has been proven to reduce metal artifacts and quantify the material property more accurately [20] [21] [22].…”

Section: Discussionmentioning

confidence: 99%

Dosimetric Effect of Cobalt-Chrome Stabilization Hardware in Paraspinal Radiation Treatments

Tang¹,

LoSasso²,

Lim³

et al. 2022

IJMPCERO

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High density materials are assigned with an apparent density of 3.2 g/cm 3 in 12-bit CT images due to saturation. This is often ignored in planning for spine tumors with titanium (density 4.40 g/cm 3 ) spinal hardware. However, new cobalt-chrome hardware has a density of 8.11 g/cm 3 , which would increase dosimetric uncertainty if the true density is not utilized in planning. This effect was evaluated in this study. Calculation accuracy was examined using MapCHECK2 with a single 20 × 10 cm 2 field with a titanium and a cobalt-chrome rod in a solid water phantom for 6X, 6FFF and 15X, at 2 cm and 6 cm beneath the rods. Measurement was compared to the calculation with density override (DO) with the true density and to the calculation with no-density override (NDO). Additionally, the dosimetric effect in clinical treatment plans was investigated for six IMRT and VMAT paraspinal cases. Plan quality was compared with the original NDO calculation and the DO recalculation. Compared to measurements, the treatment planning system (TPS) overestimated the dose locally by up to 13.2% for cobalt-chrome and 4.8% for titanium with NDO calculations. DO calculations improved the differences to 8.4% and 4.0%, respectively. Scatter from the rod increased the lateral dose and diminished as depth increased but was not properly accounted for by the TPS even with the correct density assigned. For the clinical plans, PTV coverage was lowered by an average of ~1.0% (range: 0.5% -2.0%) and ~0.3% (range: 0.2% -0.7%) in DO recalculations for cobalt-chrome and titanium, respectively. In conclusion, neglecting the true density of cobalt-chrome hardware during planning may result in an unexpected decrease in target coverage.

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Comparison of Metal Artefacts for Different Dual Energy Ct Techniques

Cited by 5 publications

References 20 publications

Metal implants on abdominal CT: does split-filter dual-energy CT provide additional value over iterative metal artifact reduction?

Metal implants on abdominal CT: does split-filter dual-energy CT provide additional value over iterative metal artifact reduction?

Application of metal artifact reduction algorithm in reducing metal artifacts in post-surgery pediatric low radiation dose spine computed tomography (CT) images

Dosimetric Effect of Cobalt-Chrome Stabilization Hardware in Paraspinal Radiation Treatments

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