Abstract
Purpose
Early deep-learning-based image denoising techniques mainly focused on a fully supervised model that learns how to generate a clean image from the noisy input (noise2clean: N2C). The aim of this study is to explore the feasibility of the self-supervised methods (noise2noise: N2N and noiser2noise: Nr2N) for PET image denoising based on the measured PET data sets by comparing their performance with the conventional N2C model.
Methods
For training and evaluating the networks, 18F-FDG brain PET/CT scan data of 14 patients was retrospectively used (10 for training and 4 for testing). From the 60-min list-mode data, we generated a total of 100 data bins with 10-s duration. We also generated 40-s-long data by adding four non-overlapping 10-s bins and 300-s-long reference data by adding all list-mode data. We employed U-Net that is widely used for various tasks in biomedical imaging to train and test proposed denoising models.
Results
All the N2C, N2N, and Nr2N were effective for improving the noisy inputs. While N2N showed equivalent PSNR to the N2C in all the noise levels, Nr2N yielded higher SSIM than N2N. N2N yielded denoised images similar to reference image with Gaussian filtering regardless of input noise level. Image contrast was better in the N2N results.
Conclusion
The self-supervised denoising method will be useful for reducing the PET scan time or radiation dose.
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Funding
This work was supported by grants from National Research Foundation of Korea (NRF) funded by Korean Ministry of Science, ICT and Future Planning (grant no. NRF-2016R1A2B3014645).
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Si Young Yie, Seung Kwan Kang, Donghwi Hwang, and Jae Sung Lee declare that there is no conflict of interest.
Ethical Approval
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. The retrospective use of the scan data was approved by the Institutional Review Board of our institute.
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Waiver of consent was approved by the Institutional Review Board of our institute.
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Yie, S.Y., Kang, S.K., Hwang, D. et al. Self-supervised PET Denoising . Nucl Med Mol Imaging 54, 299–304 (2020). https://doi.org/10.1007/s13139-020-00667-2
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DOI: https://doi.org/10.1007/s13139-020-00667-2