Objective and Subjective Image Quality of Liver Parenchyma and Hepatic Metastases with Virtual Monoenergetic Dual-source Dual-energy CT Reconstructions

Purpose To compare radiation dose, subjective and objective image quality of 3 rd generation dual-source CT (DSCT) and dual-energy CT (DECT) with conventional 64-slice single-source CT (SSCT) for pulmonary CTA. Materials and Methods 180 pulmonary CTA studies were performed in three patient cohorts of 60 patients each. Group 1: conventional SSCT 120 kV (ref.); group 2: single-energy DSCT 100 kV (ref.); group 3: DECT 90/Sn150 kV. CTDIvol, DLP, effective radiation dose were reported, and CT attenuation (HU) was measured on three central and peripheral levels. The signal-to-noise-ratio (SNR) and contrast-to-noise-ratio (CNR) were calculated. Two readers assessed subjective image quality according to a five-point scale. Results Mean CTDIvol and DLP were significantly lower in the dual-energy group compared to the SSCT group (p < 0.001 [CTDIvol]; p < 0.001 [DLP]) and the DSCT group (p = 0.003 [CTDIvol]; p = 0.003 [DLP]), respectively. The effective dose in the DECT group was 2.79 ± 0.95 mSv and significantly smaller than in the SSCT group (4.60 ± 1.68 mSv, p < 0.001) and the DSCT group (4.24 ± 2.69 mSv, p = 0.003). The SNR and CNR were significantly higher in the DSCT group (p < 0.001). Subjective image quality did not differ significantly among the three protocols and was rated good to excellent in 75 % (135/180) of cases with an inter-observer agreement of 80 %. Conclusion Dual-energy pulmonary CTA protocols of 3 rd generation dual-source scanners allow for significant reduction of radiation dose while providing excellent image quality and potential additional information by means of perfusion maps. Key Points: Citation Format

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Threshold-dependent iodine imaging and spectral separation in a whole-body photon-counting CT system

European Radiology ◽

10.1007/s00330-021-07786-0 ◽

2021 ◽

Author(s):

S. Sawall ◽

L. Klein ◽

E. Wehrse ◽

L. T. Rotkopf ◽

C. Amato ◽

...

Keyword(s):

Image Quality ◽

Photon Counting ◽

Dual Energy ◽

Whole Body ◽

Dual Energy Ct ◽

Post Mortem ◽

Tube Voltage ◽

Spectral Separation ◽

Dual Source ◽

Noise Ratio

Abstract Objective To evaluate the dual-energy (DE) performance and spectral separation with respect to iodine imaging in a photon-counting CT (PCCT) and compare it to dual-source CT (DSCT) DE imaging. Methods A semi-anthropomorphic phantom extendable with fat rings equipped with iodine vials is measured in an experimental PCCT. The system comprises a PC detector with two energy bins (20 keV, T) and (T, eU) with threshold T and tube voltage U. Measurements using the PCCT are performed at all available tube voltages (80 to 140 kV) and threshold settings (50–90 keV). Further measurements are performed using a conventional energy-integrating DSCT. Spectral separation is quantified as the relative contrast media ratio R between the energy bins and low/high images. Image noise and dose-normalized contrast-to-noise ratio (CNRD) are evaluated in resulting iodine images. All results are validated in a post-mortem angiography study. Results R of the PC detector varies between 1.2 and 2.6 and increases with higher thresholds and higher tube voltage. Reference R of the EI DSCT is found as 2.20 on average overall phantoms. Maximum CNRD in iodine images is found for T = 60/65/70/70 keV for 80/100/120/140 kV. The highest CNRD of the PCCT is obtained using 140 kV and is decreasing with decreasing tube voltage. All results could be confirmed in the post-mortem angiography study. Conclusion Intrinsically acquired DE data are able to provide iodine images similar to conventional DSCT. However, PCCT thresholds should be chosen with respect to tube voltage to maximize image quality in retrospectively derived image sets. Key Points • Photon-counting CT allows for the computation of iodine images with similar quality compared to conventional dual-source dual-energy CT. • Thresholds should be chosen as a function of the tube voltage to maximize iodine contrast-to-noise ratio in derived image sets. • Image quality of retrospectively computed image sets can be maximized using optimized threshold settings.

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Metal artefact reduction of different alloys with dual energy computed tomography (DECT)

Scientific Reports ◽

10.1038/s41598-021-81600-1 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Anand John Vellarackal ◽

Achim Hermann Kaim

Keyword(s):

Stainless Steel ◽

Image Quality ◽

Femoral Stem ◽

Dual Energy ◽

Dual Energy Ct ◽

Bony Tissue ◽

Stem Image ◽

Metal Artefact ◽

Artefact Reduction

AbstractTo evaluate the influence of dual-energy CT (DECT) and Virtual monochromatic spectral (VMS) imaging on: (1) the artefact size of geometrically identical orthopaedic implants consisting of three different compositions and (2) the image quality of the surrounding bone, three similar phantoms—each featuring one femoral stem composed of either titanium, chrome-cobalt or stainless steel surrounded by five calcium pellets (200 mg hydroxyapatite/calcium carbonate) to simulate bony tissue and one reference pellet located away from the femoral stem—were built. DECT with two sequential scans (80 kVp and 140 kVp; scan-to-scan technique) was performed, and VMS images were calculated between 40 and 190 keV. The artefact sizes were measured volumetrically by semiautomatic selection of regions of interest (ROIs), considering the VMS energies and the polychromatic spectres. Moreover, density and image noise within the pellets were measured. All three phantoms exhibit artefact size reduction as energy increases from 40 to 190 keV. Titanium exhibited a stronger reduction than chrome-cobalt and stainless steel. The artefacts were dependent on the diameter of the stem. Image quality increases with higher energies on VMS with a better depiction of surrounding structures. Monoenergetic energies 70 keV and 140 keV demonstrate superior image quality to those produced by spectral energies 80 kVp and 140 kVp.

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First experience with combined use of adaptive statistical iterative reconstruction and gemstone spectral imaging in spinal fusion CT images

10.7287/peerj.preprints.1306 ◽

2015 ◽

Author(s):

Fengdan Wang ◽

Yan Zhang ◽

Zhengyu Jin ◽

Richard Zwar

Keyword(s):

Image Quality ◽

Iterative Reconstruction ◽

Dual Energy ◽

Dual Energy Ct ◽

Metal Artifacts ◽

Adaptive Statistical Iterative Reconstruction ◽

Subjective Image Quality ◽

Gemstone Spectral Imaging ◽

Statistical Iterative Reconstruction ◽

Combined Use

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 signal-to-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%.

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Trends in radiation dose and image quality for pediatric patients with a multidetector CT and a third-generation dual-source dual-energy CT

La radiologia medica ◽

10.1007/s11547-019-01037-5 ◽

2019 ◽

Vol 124 (8) ◽

pp. 745-752 ◽

Cited By ~ 4

Author(s):

Andrea Agostini ◽

Alberto Mari ◽

Cecilia Lanza ◽

Nicolo’ Schicchi ◽

Alessandra Borgheresi ◽

...

Keyword(s):

Image Quality ◽

Radiation Dose ◽

Pediatric Patients ◽

Multidetector Ct ◽

Dual Energy ◽

Dual Energy Ct ◽

Third Generation ◽

Dual Source

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Comparison of Radiation Dose and Image Quality of Contrast-Enhanced Dual-Source CT of the Chest: Single-Versus Dual-Energy and Second-Versus Third-Generation Technology

American Journal of Roentgenology ◽

10.2214/ajr.18.20065 ◽

2019 ◽

Vol 212 (4) ◽

pp. 741-747 ◽

Cited By ~ 4

Author(s):

Lukas Lenga ◽

Doris Leithner ◽

Julia L. Peterke ◽

Moritz H. Albrecht ◽

Tomas Gudauskas ◽

...

Keyword(s):

Image Quality ◽

Radiation Dose ◽

Dual Energy ◽

Third Generation ◽

Dual Source Ct ◽

Contrast Enhanced ◽

Dual Source ◽

Single Versus ◽

Generation Technology

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Radiation dose and image quality of high-pitch emergency abdominal CT in obese patients using third-generation dual-source CT (DSCT)

Scientific Reports ◽

10.1038/s41598-019-52454-5 ◽

2019 ◽

Vol 9 (1) ◽

Author(s):

Robert Forbrig ◽

Michael Ingrisch ◽

Robert Stahl ◽

Katharina Stella Winter ◽

Maximilian Reiser ◽

...

Keyword(s):

Image Quality ◽

Radiation Dose ◽

Third Generation ◽

Obese Patients ◽

Dual Source Ct ◽

High Pitch ◽

Subjective Image Quality ◽

Dual Source ◽

Group A

Abstract In this third-generation dual-source CT (DSCT) study, we retrospectively investigated radiation dose and image quality of portal-venous high-pitch emergency CT in 60 patients (28 female, mean age 56 years) with a body mass index (BMI) ≥ 30 kg/m2. Patients were dichotomized in groups A (median BMI 31.5 kg/m2; n = 33) and B (36.8 kg/m2; n = 27). Volumetric CT dose index (CTDIvol), size-specific dose estimate (SSDE), dose length product (DLP) and effective dose (ED) were assessed. Contrast-to-noise ratio (CNR) and dose-independent figure-of-merit (FOM) CNR were calculated. Subjective image quality was assessed using a five-point scale. Mean values of CTDIvol, SSDE as well as normalized DLP and ED were 7.6 ± 1.8 mGy, 8.0 ± 1.8 mGy, 304 ± 74 mGy * cm and 5.2 ± 1.3 mSv for group A, and 12.6 ± 3.7 mGy, 11.0 ± 2.6 mGy, 521 ± 157 mGy * cm and 8.9 ± 2.7 mSv for group B (p < 0.001). CNR of the liver and spleen as well as each calculated FOM CNR were significantly higher in group A (p < 0.001). Subjective image quality was good in both groups. In conclusion, third-generation abdominal high-pitch emergency DSCT yields good image quality in obese patients. Radiation dose increases in patients with a BMI > 36.8 kg/m2.

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