Background: Model-based iterative reconstruction (MBIR) is a promising reconstruction method which could\nimprove CT image quality with low radiation dose. The purpose of this study was to demonstrate the advantage of\nusing MBIR for noise reduction and image quality improvement in low dose chest CT for children with necrotizing\npneumonia, over the adaptive statistical iterative reconstruction (ASIR) and conventional filtered back-projection\n(FBP) technique.\nMethods: Twenty-six children with necrotizing pneumonia (aged 2 months to 11 years) who underwent standard\nof care low dose CT scans were included. Thinner-slice (0.625 mm) images were retrospectively reconstructed using\nMBIR, ASIR and conventional FBP techniques. Image noise and signal-to-noise ratio (SNR) for these thin-slice images\nwere measured and statistically analyzed using ANOVA. Two radiologists independently analyzed the image quality\nfor detecting necrotic lesions, and results were compared using a Friedmanâ��s test.\nResults: Radiation dose for the overall patient population was 0.59 mSv. There was a significant improvement in\nthe high-density and low-contrast resolution of the MBIR reconstruction resulting in more detection and better\nidentification of necrotic lesions (38 lesions in 0.625 mm MBIR images vs. 29 lesions in 0.625 mm FBP images). The\nsubjective display scores (mean �± standard deviation) for the detection of necrotic lesions were 5.0 �± 0.0, 2.8 �± 0.4\nand 2.5 �± 0.5 with MBIR, ASIR and FBP reconstruction, respectively, and the respective objective image noise was 13.\n9 �± 4.0HU, 24.9 �± 6.6HU and 33.8 �± 8.7HU. The image noise decreased by 58.9 and 26.3% in MBIR images as\ncompared to FBP and ASIR images. Additionally, the SNR of MBIR images was significantly higher than FBP images\nand ASIR images.\nConclusions: The quality of chest CT images obtained by MBIR in children with necrotizing pneumonia was\nsignificantly improved by the MBIR technique as compared to the ASIR and FBP reconstruction, to provide a more\nconfident and accurate diagnosis for necrotizing pneumonia.
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