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Image quality comparison between low-dose thin-slice deep-learning reconstruction and standard-dose thick-slice
Ryota Harai1, Yasunori Nagayama1, Soichiro Ishiuchi1
1Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University, 1-1-1, Honjo, Chuo-ku, Kumamoto 860-8556, Japan.
Insights
Low-dose thin-slice deep-learning reconstruction (DLR) in pediatric abdominal CT significantly enhances image quality, improving edge sharpness and diagnostic confidence. This advanced technique offers superior visualization without increasing noise compared to standard-dose methods.
Area of Science:
- Radiology
- Medical Imaging
- Artificial Intelligence in Medicine
Background:
- Pediatric abdominal CT scans often involve a trade-off between radiation dose and image quality.
- Standard-dose thick-slice hybrid iterative reconstruction (HIR) is commonly used but may not optimize visualization of small structures.
- Low-dose protocols are desirable to reduce radiation exposure in children.
Purpose of the Study:
- To compare the image quality of low-dose thin-slice deep-learning reconstruction (DLR) with standard-dose thick-slice hybrid iterative reconstruction (HIR) in pediatric abdominal CT.
- To evaluate the impact of DLR on image noise, contrast-to-noise ratio (CNR), edge sharpness, and diagnostic confidence.
Main Methods:
- Retrospective analysis of contrast-enhanced abdominal CT scans from 82 children (≤6 years) using standard-dose (STD) or low-dose (LD) protocols.
- Images were reconstructed using HIR at 3.0-mm (STD-HIR/3.0, LD-HIR/3.0) and LD images also at 0.5-mm using HIR (LD-HIR/0.5) and DLR (LD-DLR/0.5).
- Quantitative analysis included size-specific dose estimate (SSDE), image noise, CNR, noise power spectrum (NPS), and edge-rise slope (ERS); subjective evaluation assessed noise, sharpness, structure delineation, and diagnostic confidence.
Main Results:
- Low-dose protocols achieved a 59.5% reduction in SSDE compared to standard-dose.
- LD-DLR/0.5 demonstrated lower image noise than STD-HIR/3.0, LD-HIR/3.0, and LD-HIR/0.5.
- LD-DLR/0.5 showed equivalent CNR and higher edge-rise slope (ERS) compared to STD-HIR/3.0, with similar noise texture (NPS).
- Subjective image quality scores, including diagnostic confidence, were significantly higher for LD-DLR/0.5 than for STD-HIR/3.0.
Conclusions:
- Low-dose thin-slice DLR significantly improves image quality in pediatric abdominal CT.
- DLR enhances edge sharpness, small structure visualization, and diagnostic confidence.
- This technique offers a promising approach to reduce radiation dose while maintaining or improving diagnostic image quality in pediatric patients.
Objectives:
To compare image quality between low-dose thin-slice deep-learning reconstruction (DLR) and standard-dose thick-slice hybrid iterative reconstruction (HIR) in pediatric abdominal CT.
Methods:
82 children (≤6 years) who underwent contrast-enhanced abdominal CT with standard-dose (STD, n = 41) or low-dose (LD, n = 41) protocol matched by age and weight were retrospectively identified. STD and LD images were reconstructed at 3.0-mm using HIR (STD-HIR/3.0 and LD-HIR/3.0, respectively). LD images were also reconstructed at 0.5-mm using HIR (LD-HIR/0.5) and DLR (LD-DLR/0.5). Size-specific dose estimate (SSDE) was compared between groups. Image noise and contrast-to-noise ratio (CNR) were quantified. Noise power spectrum (NPS) and edge-rise slope (ERS) were employed for noise texture and edge sharpness measures, respectively. For subjective evaluation, noise magnitude, noise texture, edge sharpness, delineation of small structures, and diagnostic confidence were rated on a 5-point scale (1 = undiagnostic, 5 = best).
Results:
SSDE was on average 59.5% lower in LD than in STD group (1.7 ± 0.4 vs. 4.2 ± 0.8 mGy, p < 0.001). Image noise was lower in LD-DLR/0.5 compared to STD-HIR/3.0, LD-HIR/3.0, and LD-HIR/0.5 (8.7 ± 1.5, 9.6 ± 1.1, 11.7 ± 1.9, and 17.9 ± 2.3 HU, respectively, all p ≤ 0.017). LD-DLR/0.5 showed equivalent CNR (e.g., liver CNR: 7.1 ± 2.1 vs. 7.0 ± 2.8, p = 0.827) and higher ERS (64.3 ± 23.9 vs. 53.3 ± 10.6 HU/mm, p = 0.011) with similar average NPS frequency (0.281 ± 0.042 vs. 0.291 ± 0.027 mm-1, p = 0.177) compared to STD-HIR/3.0. Subjective scores for all criteria were higher in LD-DLR/0.5 than in STD-HIR/3.0 (e.g., diagnostic confidence score: 4.5 ± 0.5 vs. 3.4 ± 0.4, p < 0.001).
Conclusion:
Low-dose thin-slice DLR improved edge sharpness, small structure visualization, and diagnostic confidence in pediatric abdominal CT without increasing noise compared to standard-dose thick-slice HIR.
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