Reconstructing and analyzing the invariances of low‐dose CT image denoising networks

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Main Authors: Elias Eulig, Fabian Jäger, Joscha Maier, Björn Ommer, Marc Kachelrieß
Format: Artículo Open Access
Published: Wiley 2024
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author Elias Eulig
Fabian Jäger
Joscha Maier
Björn Ommer
Marc Kachelrieß
author_facet Elias Eulig
Fabian Jäger
Joscha Maier
Björn Ommer
Marc Kachelrieß
Elias Eulig
Fabian Jäger
Joscha Maier
Björn Ommer
Marc Kachelrieß
collection Wiley Open Access
contents Reconstructing and analyzing the invariances of low‐dose CT image denoising networks Elias Eulig Fabian Jäger Joscha Maier Björn Ommer Marc Kachelrieß Medical Physics AbstractBackgroundDeep learning‐based methods led to significant advancements in many areas of medical imaging, most of which are concerned with the reduction of artifacts caused by motion, scatter, or noise. However, with most neural networks being black boxes, they remain notoriously difficult to interpret, hindering their clinical implementation. In particular, it has been shown that networks exhibit invariances w.r.t. input features, that is, they learn to ignore certain information in the input data.PurposeTo improve the interpretability of deep learning‐based low‐dose CT image denoising networks.MethodsWe learn a complete data representation of low‐dose input images using a conditional variational autoencoder (cVAE). In this representation, invariances of any given denoising network are then disentangled from the information it is not invariant to using a conditional invertible neural network (cINN). At test time, image‐space invariances are generated by applying the inverse of the cINN and subsequent decoding using the cVAE. We propose two methods to analyze sampled invariances and to find those that correspond to alterations of anatomical structures.ResultsThe proposed method is applied to four popular deep learning‐based low‐dose CT image denoising networks. We find that the networks are not only invariant to noise amplitude and realizations, but also to anatomical structures.ConclusionsThe proposed method is capable of reconstructing and analyzing invariances of deep learning‐based low‐dose CT image denoising networks. This is an important step toward interpreting deep learning‐based methods for medical imaging, which is essential for their clinical implementation. 10.1002/mp.17413 http://creativecommons.org/licenses/by/4.0/
doi_str_mv 10.1002/mp.17413
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institution Wiley Open Access
license_str_mv http://creativecommons.org/licenses/by/4.0/
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spellingShingle Reconstructing and analyzing the invariances of low‐dose CT image denoising networks
Elias Eulig
Fabian Jäger
Joscha Maier
Björn Ommer
Marc Kachelrieß
Medical Physics
Reconstructing and analyzing the invariances of low‐dose CT image denoising networks Elias Eulig Fabian Jäger Joscha Maier Björn Ommer Marc Kachelrieß Medical Physics AbstractBackgroundDeep learning‐based methods led to significant advancements in many areas of medical imaging, most of which are concerned with the reduction of artifacts caused by motion, scatter, or noise. However, with most neural networks being black boxes, they remain notoriously difficult to interpret, hindering their clinical implementation. In particular, it has been shown that networks exhibit invariances w.r.t. input features, that is, they learn to ignore certain information in the input data.PurposeTo improve the interpretability of deep learning‐based low‐dose CT image denoising networks.MethodsWe learn a complete data representation of low‐dose input images using a conditional variational autoencoder (cVAE). In this representation, invariances of any given denoising network are then disentangled from the information it is not invariant to using a conditional invertible neural network (cINN). At test time, image‐space invariances are generated by applying the inverse of the cINN and subsequent decoding using the cVAE. We propose two methods to analyze sampled invariances and to find those that correspond to alterations of anatomical structures.ResultsThe proposed method is applied to four popular deep learning‐based low‐dose CT image denoising networks. We find that the networks are not only invariant to noise amplitude and realizations, but also to anatomical structures.ConclusionsThe proposed method is capable of reconstructing and analyzing invariances of deep learning‐based low‐dose CT image denoising networks. This is an important step toward interpreting deep learning‐based methods for medical imaging, which is essential for their clinical implementation. 10.1002/mp.17413 http://creativecommons.org/licenses/by/4.0/
title Reconstructing and analyzing the invariances of low‐dose CT image denoising networks
topic Medical Physics
url https://aapm.onlinelibrary.wiley.com/doi/10.1002/mp.17413