The Optimal Energy Level of Virtual Monochromatic Images From Spectral CT for Reducing Beam-Hardening Artifacts Due to Contrast Media in the Thorax

Kim, Cherry; Kim, Dajung; Lee, Ki Yeol; Kim, Haesol; Cha, Jaehyung; Choo, Ji Yung; Cho, Pyong Kon

doi:10.2214/ajr.17.19377

Cited by 18 publications

(16 citation statements)

References 19 publications

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“…For visual assessment besides CI, we chose VMI reconstruction levels with larger increments (70, 100, 130, 160, and 200 keV) to allow for detection of relevant changes in image assessment and to not obscure differences by repetitive rating of (too) similar images, as applied before (3,16). The following image parameters were used: slice thickness = 3 mm; axial plane; soft tissue window settings (window level = 60, window width = 350); readers were allowed to adapt window settings manually.…”

Section: Methodsmentioning

confidence: 99%

“…Fast image acquisition as enabled by multidetector computed tomography (CT) requires adequate and optimized contrast media (CM) injection protocols (1). High CM concentration is required for multiple clinical indications, such as angiographies, detection of hypervascular liver lesions, and parenchymal depiction; however, high CM concentrations can lead to severe perivenous hypo- and hyperattenuating artifacts (1–4). When brachial injection is used, these artifacts typically arise around the junction of the axillary and subclavian veins impairing diagnostic assessment of local vascular structures and adjacent soft tissue (e.g.…”

Section: Introductionmentioning

confidence: 99%

“…Several studies have already shown the potential of high-keV VMI from DECT for metal artifact reduction; however, available data on using this approach for artifacts from CM are limited (3,15,16). Therefore, this study investigates the effectiveness of VMI from SDCT to reduce artifacts from CM in the axillary and subclavian veins.…”

Section: Introductionmentioning

confidence: 99%

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Role of spectral-detector CT in reduction of artifacts from contrast media in axillary and subclavian veins: single institution study in 50 patients

et al. 2019

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Background In CT imaging, a high concentration of iodinated contrast media in axillary and subclavian veins after brachial application can cause perivenous artifacts impairing diagnostic assessment of local vascular structures and soft tissue. Purpose To investigate reduction of perivenous hypo- and hyperattenuating artifacts of the axillary and subclavian veins using virtual monoenergetic images (VMI) in comparison to conventional CT images (CI), acquired on spectral-detector CT. Material and Methods 50 spectral-detector CT datasets of patients with perivenous artifacts from contrast media were included in this retrospective, institutional review board-approved study. CT images and virtual monoenergetic images (range 40–200 keV, 10-keV increments) were reconstructed from the same scans. Quantitative analysis was performed by region of interest-based assessment of mean attenuation (HU) and standard deviation in most pronounced hypo- and hyperdense artifacts and artifact-impaired arteries as well as muscle. Visually, artifact reduction, assessment of vessels, and surrounding soft tissue were rated on 5-point Likert-scales by two radiologists. Results In comparison to CT images, virtual monoenergetic images of ≥90 keV showed a significant reduction of hypo- and hyperattenuating artifacts (hypodense: CI -220.0±171.2 HU; VMI130keV -13.4±49.1 HU; hyperdense: CI 274.6±184.4 HU; VMI130keV 24.2±84.9 HU; P<0.001). Subjective analysis confirmed that virtual-monoenergetic images of ≥100 keV significantly reduced artifacts (hypodense: CI 2[1–3]; VMI130keV 5[4–5], hyperdense: CI 2[1–4]; VMI130keV 5[5–5], P<0.001) and improved diagnostic assessment. Best results for diagnostic assessment were noted for virtual monoenergetic images at 130 keV. Overcorrection of artifacts was observed at higher keV values. Interrater agreement was excellent for each evaluation and keV value (intraclass correlation coefficient 0.89). Conclusion Higher keV virtual monoenergetic images yielded significant reduction of contrast media artifacts and led to improved assessment of vessels and surrounding soft tissue. Recommended keV values for best diagnostic assessment are in the range of 100–160 keV.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Role of spectral-detector CT in reduction of artifacts from contrast media in axillary and subclavian veins: single institution study in 50 patients

et al. 2019

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“…In a recent study of a vertebra phantom, virtual monoenergetic images were superior to other metal artifact reduction algorithms in the evaluation of metal implants (61). High-kiloelectron volt images also can reduce beam-hardening artifacts from injected contrast material in the subclavian veins, axillary veins, or superior vena cava at chest CT (62).…”

Section: Oncologic Imagingmentioning

confidence: 99%

Dual-Energy CT in Children: Imaging Algorithms and Clinical Applications

Siegel

Ramírez-Giraldo

2019

Radiology

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Dual-energy CT enables the simultaneous acquisition of CT images at two different x-ray energy spectra. By acquiring high-and low-energy spectral data, dual-energy CT can provide unique qualitative and quantitative information about tissue composition, allowing differentiation of multiple materials including iodinated contrast agents. The two dual-energy CT postprocessing techniques that best exploit the advantages of dual-energy CT in children are the material-decomposition images (which include virtual nonenhanced, iodine, perfused lung blood volume, lung vessel, automated bone removal, and renal stone characterization images) and virtual monoenergetic images. Clinical applications include assessment of the arterial system, lung perfusion, neoplasm, bowel diseases, renal calculi, tumor response to treatment, and metal implants. Of importance, the radiation exposure level of dual-energy CT is equivalent to or less than that of conventional single-energy CT. In this review, the authors discuss the basic principles of the dual-energy CT technologies and postprocessing techniques and review current clinical applications in the pediatric chest and abdomen.

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“…An important reason for the low repeatability of subsolid nodule measurement in low-dose CT is the presence of beam-hardening artifacts (7). Because monoenergetic images of recently used spectral CTs are effective in reducing the beam-hardening artifacts (10)(11)(12), the use of monoenergetic images may increase the measurement repeatability of subsolid nodules in low-dose CT. Therefore, our phantom study aimed to determine whether monoenergetic images captured with dual-layer spectral CT can improve the repeatability of subsolid nodule measurement and whether this approach can further reduce the radiation dose of CT while maintaining measurement repeatability.…”

Section: Original Articlementioning

confidence: 99%

Improved repeatability of subsolid nodule measurement in low-dose lung screening with monoenergetic images: a phantom study

Kim

Lee

Kim

2019

Quant. Imaging Med. Surg

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Background: To investigate whether monoenergetic images captured with dual-layer spectral computed tomography (CT) can improve the repeatability of subsolid nodule measurement, and whether this approach can further reduce the radiation dose of CT while maintaining its measurement repeatability. Methods: An anthropomorphic phantom with simulated subsolid nodules at three different levels was repeatedly scanned with both conventional single-energy CT and dual-layer spectral CT. A proxy for the measurement repeatability in the National Lung Screening Trial (proxy for NLST) was calculated with the typical CT protocol used in NLST. Using the dual-layer spectral CT, monoenergetic images of 40 to 110 keV, with an interval of 10 keV, were generated. The average diameter and volume of a total of 15,120 nodules in 840 CT images were measured by using a commercially-available computer-aided detection (CAD) system. The repeatability coefficient (RC), %RC, and 95% confidence intervals (CIs) of each image set were calculated and compared. Results: At the same tube voltage and tube current-time product, monoenergetic images resulted in significantly lower RC than the proxy for NLST, indicating that measurement repeatability was enhanced. When the radiation dose was lowered by 30% or 55%, monoenergetic images showed significantly lower RC at high-energy keV than the proxy for NLST. The estimated measurement repeatability from monoenergetic images with 30% or 55% lower radiation dose was comparable to the repeatability from conventional singleenergy CT images with standard radiation dose and iterative reconstruction. Conclusions: Monoenergetic images captured by using dual-layer spectral CT can improve the repeatability of subsolid nodule measurement. The use of monoenergetic images would allow lung cancer screening with a lower radiation dose, while maintaining comparable measurement repeatability.

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The Optimal Energy Level of Virtual Monochromatic Images From Spectral CT for Reducing Beam-Hardening Artifacts Due to Contrast Media in the Thorax

Abstract: Virtual monochromatic imaging reduced beam-hardening artifacts and improved image quality, and optimal evaluation of chest CT was best achieved at 100 and 130 keV.

Cited by 18 publications

References 19 publications

Role of spectral-detector CT in reduction of artifacts from contrast media in axillary and subclavian veins: single institution study in 50 patients

Role of spectral-detector CT in reduction of artifacts from contrast media in axillary and subclavian veins: single institution study in 50 patients

Dual-Energy CT in Children: Imaging Algorithms and Clinical Applications

Improved repeatability of subsolid nodule measurement in low-dose lung screening with monoenergetic images: a phantom study

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