Performance of four dual-energy CT platforms for abdominal imaging: a task-based image quality assessment based on phantom data

Greffier, Joël; Dabli, Djamel; Forges, Hélène de; Hamard, Aymeric; Douek, Philippe; Beregi, Jean Paul; Frandon, Julien

doi:10.1007/s00330-020-07671-2

Cited by 31 publications

(51 citation statements)

References 41 publications

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“…Here, the highest TTF50 values were found for VMI at 40 keV and a shift towards lower frequencies was observed with increasing VMI-energy (24,25,34). The authors hypothesized that this finding was related to changes of the enhancement of the border of the acrylic insert with decreasing VMI-energy which introduced on overshoot on the edge spread function (ESF) curves which improved the TTF (24,34). We observed the same effect for the polystyrene in our study as demonstrated by the increased slopes of the ESF curves at low VMI-energies.…”

Section: Spatial Resolutionmentioning

confidence: 69%

“…An increase in spatial resolution at low keV-energies has been also described by Greffier et al in three studies in which an acrylic insert was used. Here, the highest TTF50 values were found for VMI at 40 keV and a shift towards lower frequencies was observed with increasing VMI-energy (24,25,34). The authors hypothesized that this finding was related to changes of the enhancement of the border of the acrylic insert with decreasing VMI-energy which introduced on overshoot on the edge spread function (ESF) curves which improved the TTF (24,34).…”

Section: Spatial Resolutionmentioning

confidence: 84%

“…Because VMI at certain keVs have been described as being subjectively blotchy or patchy (23), potential differences in noise texture may influence detectability and hamper their widespread implementation into routine clinical practice. Recently, task-based image quality parameters have been investigated for VMI at 40-140 keV among four different DECT approaches (24) as well as for different reconstruction algorithms on a dual-source dual-energy CT (25). In both studies, the authors found differences in image noise texture, spatial resolution as well as d' depending on the imaging setup and VMI-energy.…”

Section: Introductionmentioning

confidence: 99%

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Virtual monoenergetic images from dual-energy CT: systematic assessment of task-based image quality performance

Cester¹,

Eberhard²,

Alkadhi³

et al. 2022

Quant Imaging Med Surg

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Background: To compare task-based image quality (TB-IQ) among virtual monoenergetic images (VMI) and linear-blended images (LBI) from dual-energy CT as a function of contrast task, radiation dose, size, and lesion diameter.Methods: A TB-IQ phantom (Mercury Phantom 4.0, Sun Nuclear Corporation) was imaged on a thirdgeneration dual-source dual-energy CT with 100/Sn150 kVp at three volume CT dose levels (5, 10, 15 mGy).Three size sections (diameters 16, 26, 36 cm) with subsections for image noise and spatial resolution analysis were used. High-contrast tasks (e.g., calcium-containing stone and vascular lesion) were emulated using bone and iodine inserts. A low-contrast task (e.g., low-contrast lesion or hematoma) was emulated using a polystyrene insert. VMI at 40-190 keV and LBI were reconstructed. Noise power spectrum (NPS) determined the noise magnitude and texture. Spatial resolution was assessed using the task-transfer function (TTF) of the three inserts. The detectability index (d') served as TB-IQ metric.Results: Noise magnitude increased with increasing phantom size, decreasing dose, and decreasing VMIenergy. Overall, noise magnitude was higher for VMI at 40-60 keV compared to LBI (range of noise increase, 3-124%). Blotchier noise texture was found for low and high VMIs (40-60 keV, 130-190 keV) compared to LBI. No difference in spatial resolution was observed for high contrast tasks. d' increased with increasing dose level or lesion diameter and decreasing size. For high-contrast tasks, d' was higher at 40-80 keV and lower at high VMIs. For the low-contrast task, d' was higher for VMI at 70-90 keV and lower at 40-60 keV.Conclusions: Task-based image quality differed among VMI-energy and LBI dependent on the contrast task, dose level, phantom size, and lesion diameter. Image quality could be optimized by tailoring VMIenergy to the contrast task. Considering the clinical relevance of iodine, VMIs at 50-60 keV could be proposed as an alternative to LBI.

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Section: Spatial Resolutionmentioning

confidence: 69%

Section: Spatial Resolutionmentioning

confidence: 84%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Virtual monoenergetic images from dual-energy CT: systematic assessment of task-based image quality performance

Cester¹,

Eberhard²,

Alkadhi³

et al. 2022

Quant Imaging Med Surg

View full text Add to dashboard Cite

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“…Finally, spectral images are obtained from the basis material images (photoelectric and Compton) generated by the spectral decomposition in the image domain (“post‐reconstruction processing”) for DSCT. Virtual monoenergetic images (VMIs) are calculated as a linear combination of the basis material images with energy‐dependent coefficients, which approximate the energy dependence of the photoelectric interaction and the energy dependence of the total cross‐section for Compton scattering respectively 11–13 . This type of images are useful for enhancing iodine contrast on abdominal lesions (such as focal liver lesions) at low monoenergetic levels (ranging from 40 to 60 keV) and reducing metallic artifacts at high monoenergetic levels (ranging from 140 to 190 keV).…”

Section: Introductionmentioning

confidence: 99%

“…Virtual monoenergetic images (VMIs) are calculated as a linear combination of the basis material images with energy‐dependent coefficients, which approximate the energy dependence of the photoelectric interaction and the energy dependence of the total cross‐section for Compton scattering respectively. 11 , 12 , 13 This type of images are useful for enhancing iodine contrast on abdominal lesions (such as focal liver lesions) at low monoenergetic levels (ranging from 40 to 60 keV) and reducing metallic artifacts at high monoenergetic levels (ranging from 140 to 190 keV). In addition, virtual contrast images or iodine maps are generated to enhance the visualization of the iodine contrast distribution.…”

Section: Introductionmentioning

confidence: 99%

Impact of four kVp combinations available in a dual‐source CT on the spectral performance of abdominal imaging: A task‐based image quality assessment on phantom data

Greffier¹,

Frandon²,

Sadate³

et al. 2021

J Applied Clin Med Phys

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To compare the spectral performance of four combinations of kVp available in a third generation dual-source CT (DSCT) on abdominal imaging. Methods: An image-quality phantom was scanned with a DSCT using four kVp pairs (tube "A" voltage/tube "B" voltage): 100/Sn150 kVp, 90/Sn150 kVp, 80/Sn150 kVp, and 70/Sn150 kVp, classic parameters and dose level for abdomen examination (CTDI vol : 11 mGy). The noise power spectrum (NPS) and the task-based transfer function (TTF) of two inserts were computed on virtual monochromatic images (VMIs) at 40/50/60/70 keV and for mixed, low-, and high-kVp images. Detectability index (d') was computed on VMIs and mixed images to model the detection task of liver metastasis (LM) and hepatocellular carcinoma (HCC). Iodine quantification accuracy was assessed using the Root Mean Square Deviation (RMSD iodine ) and the iodine bias (IB).Results: Noise magnitude decreased by −55%± 0% between 40 and 70 keV for all kVp pairs. Compared to 70/Sn150 kVp, noise magnitude was increased by 9% ± 0% with 80/Sn150 kVp, by 16% ± 1% with 90/Sn150 kVp and by 24%± 1% with 100/Sn150 kVp. The average NPS spatial frequency (f av ) shifted toward higher frequencies as energy level increased for all kVp pairs. Lowest f av values were found for 70/Sn150 kVp and highest for 100/Sn150 kVp. The value of TTF at 50% (f 50 ) shifted toward lower frequencies with increasing energy level. The highest f 50 values occurred for 100/Sn150 kVp and the lowest for 80/ Sn150 kVp. For both lesions, d' was highest for 70/Sn150 kVp and lowest for 100/Sn150 kVp. Compared to 70/Sn150 kVp, d' decreased by −6% ± 3% with 80/Sn150 kVp, by −11% ± 2% with 90/Sn150 kVp and by −13%± 2% with 100/ Sn150 kVp. For all acquisitions, the RSMD iodine and IB were the lowest for 100/ Sn150 kVp (0.29 ± 0.10 mg/ml and 0.88 ± 0.30 mg/ml, respectively) and increased when the tube "A" voltage decreased (2.34 ± 0.29 mg/ml for 70/Sn150 kVp and 7.42 ± 0.51 mg/ml respectively).

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Phantom task‐based image quality assessment of three generations of rapid kV‐switching dual‐energy CT systems on virtual monoenergetic images

et al. 2022

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Purpose To compare the spectral performance of three rapid kV switching dual‐energy CT (DECT) systems on virtual monoenergetic images (VMIs) at low‐energy levels on abdominal imaging. Methods A multi‐energy phantom was scanned on three DECT systems equipped with three different gemstone spectral imaging (GSI) platforms: GSI (1st generation, GSI‐1st), GSI‐Pro (2nd generation, GSI‐2nd ), and GSI‐Xtream (3rd generation, GSI‐3rd). Acquisitions on the phantom were performed with a CTDIvol close to 11mGy. For all platforms, raw data were reconstructed using filtered‐back projection (FBP) and a hybrid iterative reconstruction algorithm (ASIR‐V at 50%; AV50). A deep‐learning image reconstruction (DLR) algorithm (TrueFidelity) was used only for the GSI‐3rd. Noise power spectrum (NPS) and task‐based transfer function (TTF) were evaluated from 40 to 80 keV of VMIs. A detectability index (d′) was computed to assess the detection of two contrast‐enhanced lesions according to the keV level used. Results For all GSI platforms, the noise magnitude decreased from 40 to 70 keV, and using AV50 compared to FBP. The average NPS spatial frequency (fav) and spatial resolution (TTF50%) were similar from 40 to 70 keV and decreased with AV50 compared to FBP. Compared to AV50, using DLR reduced the noise magnitude (−27% ± 3%) and improved fav values (10% ± 0%) and altering spatial resolution (2% ± 5%). For the two lesions, d′ values peaked at 70 keV for GSI‐1st and GSI‐2nd platforms and at 40/50 keV for GSI‐3rd, for all reconstruction algorithms. The highest d′ values were found for the GSI‐3rd with DLR. Conclusion Differences in image quality were found between the GSI platforms for VMIs at low keV. The new DLR algorithm on the GSI‐3rd platform reduced noise and improved spatial resolution and detectability without changing the noise texture for VMIs at low keV. The choice of the best energy level in VMIs depends on the platform and the reconstruction algorithm.

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Performance of four dual-energy CT platforms for abdominal imaging: a task-based image quality assessment based on phantom data

Cited by 31 publications

References 41 publications

Virtual monoenergetic images from dual-energy CT: systematic assessment of task-based image quality performance

Virtual monoenergetic images from dual-energy CT: systematic assessment of task-based image quality performance

Impact of four kVp combinations available in a dual‐source CT on the spectral performance of abdominal imaging: A task‐based image quality assessment on phantom data

Phantom task‐based image quality assessment of three generations of rapid kV‐switching dual‐energy CT systems on virtual monoenergetic images

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