Impact of dose reduction and the use of an advanced model-based iterative reconstruction algorithm on spectral performance of a dual-source CT system: A task-based image quality assessment

Greffier, Joël; Dabli, Djamel; Hamard, Aymeric; Akessoul, Philippe; Belaouni, Asmaa; Beregi, Jean‐Paul; Frandon, Julien

doi:10.1016/j.diii.2021.03.002

Cited by 28 publications

(17 citation statements)

References 29 publications

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“…These showed frequency shifts to lower frequencies compared to LBI indicating blotchier noise texture. This finding is in line with the results by Greffier et al who found a peak in the average spatial frequency at 70 keV with a shift towards lower frequencies from 70-40 and 70-100 keV on the same dual-source DECT system (25). We found comparable noise…”

Section: Noise Magnitude and Texturesupporting

confidence: 94%

“…Interestingly, d' increased slightly from 40 to 50 keV for the iodine contrast task before decreasing with increasing VMIenergy. This behavior is comparable to the insert with lower iodine concentration (2 mgI/mL) in the study by Greffier et al (25) while it differs from the insert with higher iodine concentration (4 mgI/mL) for which a decrease of d' was observed for VMI-energies higher than 40 keV (24,25). As a general observation, our results indicate that the optimization of VMI-energy offers potential for dose reduction.…”

Section: Detectabilitysupporting

confidence: 85%

“…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: Noise Magnitude and Texturesupporting

confidence: 94%

Section: Detectabilitysupporting

confidence: 85%

Section: Spatial Resolutionmentioning

confidence: 84%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

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

show abstract

“…This comparison was performed on VMIs and iodine maps reconstructed only with Filtered Back Projection (FBP) using parameters and dose levels close to those used in clinical practice for DECT examinations of the abdomen. Spectral performance was studied using a task-based image quality assessment (noise magnitude, noise texture, spatial resolution and detectability of contrastenhanced lesions) often used in conventional single-energy CT (SECT) (13)(14)(15)(16)(17)(18)(19)(20)(21)(22) and increasingly used in DECT (12,23,24). However, this study did not compare the spectral performance of these platforms with the use of IR (hybrid or advanced/partial Model-based IR) algorithms used in clinical practice.…”

Section: Introductionmentioning

confidence: 99%

Comparison of virtual monoenergetic imaging between a rapid kilovoltage switching dual-energy computed tomography with deep-learning and four dual-energy CTs with iterative reconstruction

Greffier¹,

Guiu²,

Frandon³

et al. 2022

Quant Imaging Med Surg

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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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Impact of dose reduction and the use of an advanced model-based iterative reconstruction algorithm on spectral performance of a dual-source CT system: A task-based image quality assessment

Cited by 28 publications

References 29 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

Comparison of virtual monoenergetic imaging between a rapid kilovoltage switching dual-energy computed tomography with deep-learning and four dual-energy CTs with iterative reconstruction

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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