Diagnostic performance of reduced-dose CT with a hybrid iterative reconstruction algorithm for the detection of hypervascular liver lesions: a phantom study
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To investigate the diagnostic performance of reduced-dose CT with a hybrid iterative reconstruction (IR) algorithm for the detection of hypervascular liver lesions.
Thirty liver phantoms with or without simulated hypervascular lesions were scanned with a 320-slice CT scanner with control-dose (40 mAs) and reduced-dose (30 and 20 mAs) settings. Control-dose images were reconstructed with filtered back projection (FBP), and reduced-dose images were reconstructed with FBP and a hybrid IR algorithm. Objective image noise and the lesion to liver contrast-to-noise ratio (CNR) were evaluated quantitatively. Images were interpreted independently by 2 blinded radiologists, and jackknife alternative free-response receiver-operating characteristic (JAFROC) analysis was performed.
Hybrid IR images with reduced-dose settings (both 30 and 20 mAs) yielded significantly lower objective image noise and higher CNR than control-dose FBP images (P < .05). However, hybrid IR images with reduced-dose settings had lower JAFROC1 figure of merit than control-dose FBP images, although only the difference between 20 mAs images and control-dose FBP images was significant for both readers (P < .01).
An aggressive reduction of the radiation dose would impair the detectability of hypervascular liver lesions, although objective image noise and CNR would be preserved by a hybrid IR algorithm.
• A half-dose scan with a hybrid iterative reconstruction preserves objective image quality.
• A hybrid iterative reconstruction algorithm does not improve diagnostic performance.
• An aggressive dose reduction would impair the detectability of low-contrast lesions.
KeywordsDiagnostic imaging Multidetector computed tomography Image reconstruction Radiation dosage Liver
Filtered back projection
- AIDR 3D
Adaptive iterative dose reduction 3-dimensional
Quantum denoising filter
The scientific guarantor of this publication is Yoshifumi Narumi. The authors of this manuscript declare no relationships with any companies, whose products or services may be related to the subject matter of the article. This study has received funding by Japan Society for the Promotion of Science. No complex statistical methods were necessary for this paper. Institutional Review Board approval was not required because this study was not on human subjects. Written informed consent was not required for this study because this study was not on human subjects. Approval from the institutional animal care committee was not required because this study was not on animals. No study subjects or cohorts have been previously reported. Methodology: prospective, experimental, performed at one institution.
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