Image quality characteristics for virtual monoenergetic images using dual-layer spectral detector CT: Comparison with conventional tube-voltage images

2018 ◽  
Vol 49 ◽  
pp. 5-10 ◽  
Author(s):  
Daisuke Sakabe ◽  
Yoshinori Funama ◽  
Katsuyuki Taguchi ◽  
Takeshi Nakaura ◽  
Daisuke Utsunomiya ◽  
...  
Keyword(s):  
Image Quality ◽  
Quality Characteristics ◽  
Tube Voltage ◽  
Spectral Detector Ct ◽  
Virtual Monoenergetic Images ◽  
Monoenergetic Images

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

2019 ◽  
Vol 61 (4) ◽  
pp. 450-460 ◽  
Author(s):  
Kai Roman Laukamp ◽  
Amit Gupta ◽  
Nils Große Hokamp ◽  
Verena Carola Obmann ◽  
Frank Philipp Graner ◽  
...  
Keyword(s):  
Soft Tissue ◽  
Contrast Media ◽  
Intraclass Correlation ◽  
Ct Images ◽  
Diagnostic Assessment ◽  
Surrounding Soft Tissue ◽  
Iodinated Contrast ◽  
Spectral Detector Ct ◽  
Virtual Monoenergetic Images ◽  
Monoenergetic Images

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.

Image Quality on Dual-energy CTPA Virtual Monoenergetic Images

2018 ◽  
Vol 25 (8) ◽  
pp. 1075-1086 ◽  
Author(s):  
Bari Dane ◽  
Hersh Patel ◽  
Thomas O'Donnell ◽  
Francis Girvin ◽  
Geraldine Brusca-Augello ◽  
...  
Keyword(s):  
Image Quality ◽  
Dual Energy ◽  
Virtual Monoenergetic Images ◽  
Monoenergetic Images

scholarly journals Dual-Layer Spectral CTA for TAVI Planning Using a Split-Phase Protocol and Low-keV Virtual Monoenergetic Images: Improved Image Quality in Comparison with Single-Phase Conventional CTA

2021 ◽  
Author(s):  
David Mangold ◽  
Janek Salatzki ◽  
Johannes Riffel ◽  
Hans-Ulrich Kauczor ◽  
Tim Frederik Weber
Keyword(s):  
Image Quality ◽  
Ct Angiography ◽  
Single Phase ◽  
Access Route ◽  
Ct Scanner ◽  
Arterial Access ◽  
Transcatheter Aortic Valve ◽  
Gated Acquisition ◽  
Virtual Monoenergetic Images ◽  
Monoenergetic Images

Purpose Adaptation of computed tomography protocols for transcatheter aortic valve implantation (TAVI) planning is required when a first-generation dual-layer spectral CT scanner (DLCT) is used. The purpose of this study was to evaluate the objective image quality of aortic CT angiography (CTA) for TAVI planning using a split-phase technique with reconstruction of 40 keV virtual monoenergetic images (40 keV-VMI) obtained with a DLCT scanner. CT angiography obtained with a single-phase protocol of a conventional single-detector CT (SLCT) was used for comparison. Materials and Methods 75 CTA scans from DLCT were retrospectively compared to 75 CTA scans from SLCT. For DLCT, spiral CTA without ECG-synchronization was performed immediately after a retrospectively ECG-gated acquisition covering the heart and aortic arch. For SLCT, spiral CTA with retrospective ECG-gating was performed to capture the heart and the access route simultaneously in one scan. Objective image quality was compared at different levels of the arterial access route. Results 40 keV virtual monoenergetic images of DLCT showed a significantly higher mean vessel attenuation, SNR, and CNR at all levels of the arterial access route. With 40 keV-VMI of DLCT, the overall mean aortic attenuation of all six measured regions was 589.6 ± 243 HU compared to 492.7 ± 209 HU of SLCT (p < 0.01). A similar trend could be observed for SNR (23.6 ± 18 vs. 18.6 ± 9; p < 0.01) and CNR (21.1 ± 18 vs. 16.4 ± 8; p < 0.01). No deterioration was observed for vascular noise (27.8 ± 9 HU vs. 28.1 ± 8 HU; p = 0.599). Conclusion Using a DLCT scanner with a split-phase protocol and 40 keV-VMI for TAVI planning, higher objective image quality can be obtained compared to a single-phase protocol of a conventional CT scanner. Key Points:  Citation Format

scholarly journals Virtual monoenergetic images from spectral detector computed tomography facilitate washout assessment in arterially hyper-enhancing liver lesions

2020 ◽  
Author(s):  
R. P. Reimer ◽  
N. Große Hokamp ◽  
A. Fehrmann Efferoth ◽  
A. Krauskopf ◽  
D. Zopfs ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Image Quality ◽  
Visual Analysis ◽  
Quality Parameters ◽  
Wilcoxon Test ◽  
Liver Lesions ◽  
Diagnostic Confidence ◽  
Virtual Monoenergetic Images ◽  
Noise Ratio ◽  
Monoenergetic Images

Abstract Objectives To investigate whether the increased soft tissue contrast of virtual monoenergetic images (VMIs) obtained from a spectral detector computed tomography (SDCT) system improves washout assessment of arterially hyper-enhancing liver lesions. Methods Fifty-nine arterially hyper-enhancing lesions in 31 patients (age 65 ± 9 years, M/W 20/11) were included in this IRB-approved study. All patients underwent multi-phase SDCT for HCC screening. MRI, CEUS or biopsy within 3 months served as standard of reference to classify lesions as LiRADS 3 or 4/5. VMIs and conventional images (CIs) were reconstructed. Visual analysis was performed on 40, 60, and 80 kiloelectronvolt (keV) and CIs by 3 radiologists. Presence and visibility of washout were assessed; image quality and confidence of washout evaluation were evaluated on 5-point Likert scales. Signal-to-noise ratio (SNR), lesion-to-liver contrast-to-noise ratio (CNR) (|HUlesion–HUliver|/SDliver) and washout (|HUlesion–HUliver|) were calculated. Statistical assessment was performed using ANOVA and Wilcoxon test. Results On subjective lesion analysis, the highest level of diagnostic confidence and highest sensitivity for the detection of lesion washout were found for 40-keV VMIs (40 keV vs. CI, 81.3 vs. 71.3%). Image quality parameters were significantly better in low-kiloelectronvolt VMIs than in CIs (p < 0.05; e.g. SNRliver: 40 keV vs. CIs, 12.5 ± 4.1 vs. 5.6 ± 1.6). In LiRADS 4/5 lesions, CNR and quantitative washout values were significantly higher in 40-keV VMIs compared to CIs (p < 0.05; e.g. CNR and washout in 40 keV vs. CIs, 2.3 ± 1.6 vs. 0.8 ± 0.5 and 29.0 ± 19.1 vs. 12.9 ± 6.9 HU, respectively). Conclusion By increasing lesion contrast, low-kiloelectronvolt VMIs obtained from SDCT improve washout assessment of hyper-enhancing liver lesions with respect to washout visibility and diagnostic confidence. Key Points • Low-kiloelectronvolt virtual monoenergetic images from spectral detector CT facilitate washout assessment in arterially hyper-enhancing liver lesions. • Image quality and quantitative washout parameters as well as subjective washout visibility and diagnostic confidence benefit from low-kiloelectronvolt virtual monoenergetic images.

Improvement of Image Quality in Unenhanced Dual-Layer CT of the Head Using Virtual Monoenergetic Images Compared With Polyenergetic Single-Energy CT

2017 ◽  
Vol 52 (8) ◽  
pp. 470-476 ◽  
Author(s):  
Victor Neuhaus ◽  
Nuran Abdullayev ◽  
Nils Große Hokamp ◽  
Gregor Pahn ◽  
Christoph Kabbasch ◽  
...  
Keyword(s):  
Image Quality ◽  
Virtual Monoenergetic Images ◽  
Monoenergetic Images

scholarly journals Reduction of CT artifacts from cardiac implantable electronic devices using a combination of virtual monoenergetic images and post-processing algorithms

2021 ◽  
Author(s):  
Lenhard Pennig ◽  
David Zopfs ◽  
Roman Gertz ◽  
Johannes Bremm ◽  
Charlotte Zaeske ◽  
...  
Keyword(s):  
Soft Tissue ◽  
Electronic Devices ◽  
Diagnostic Assessment ◽  
Artifact Reduction ◽  
Cardiac Implantable Electronic Devices ◽  
Effective Reduction ◽  
Spectral Detector Ct ◽  
Virtual Monoenergetic Images ◽  
Conventional Ct ◽  
Monoenergetic Images

Abstract Objectives To evaluate the reduction of artifacts from cardiac implantable electronic devices (CIEDs) by virtual monoenergetic images (VMI), metal artifact reduction (MAR) algorithms, and their combination (VMIMAR) derived from spectral detector CT (SDCT) of the chest compared to conventional CT images (CI). Methods In this retrospective study, we included 34 patients (mean age 74.6 ± 8.6 years), who underwent a SDCT of the chest and had a CIED in place. CI, MAR, VMI, and VMIMAR (10 keV increment, range: 100–200 keV) were reconstructed. Mean and standard deviation of attenuation (HU) among hypo- and hyperdense artifacts adjacent to CIED generator and leads were determined using ROIs. Two radiologists qualitatively evaluated artifact reduction and diagnostic assessment of adjacent tissue. Results Compared to CI, MAR and VMIMAR ≥ 100 keV significantly increased attenuation in hypodense and significantly decreased attenuation in hyperdense artifacts at CIED generator and leads (p < 0.05). VMI ≥ 100 keV alone only significantly decreased hyperdense artifacts at the generator (p < 0.05). Qualitatively, VMI ≥ 100 keV, MAR, and VMIMAR ≥ 100 keV provided significant reduction of hyper- and hypodense artifacts resulting from the generator and improved diagnostic assessment of surrounding structures (p < 0.05). Diagnostic assessment of structures adjoining to the leads was only improved by MAR and VMIMAR 100 keV (p < 0.05), whereas keV values ≥ 140 with and without MAR significantly worsened diagnostic assessment (p < 0.05). Conclusions The combination of VMI and MAR as well as MAR as a standalone approach provides effective reduction of artifacts from CIEDs. Still, higher keV values should be applied with caution due to a loss of soft tissue and vessel contrast along the leads. Key Points • The combination of VMI and MAR as well as MAR as a standalone approach enables effective reduction of artifacts from CIEDs. • Higher keV values of both VMI and VMIMARat CIED leads should be applied with caution since diagnostic assessment can be hampered by a loss of soft tissue and vessel contrast. • Recommended keV values for CIED generators are between 140 and 200 keV and for leads around 100 keV.

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