Iterative Image Reconstruction with Under-Sampled Data Assisted by a Neural Network

TL;DR

This paper introduces a new method for improving image reconstruction from incomplete data using a neural network to reduce artifacts.

Contribution

A novel Bayesian term, the CNN score, is introduced to suppress artifacts in image reconstruction using a neural network classifier.

Findings

The CNN score correlates well with the severity of artifacts in images from incomplete data.

Using the CNN score in iterative reconstruction reduces artifacts effectively.

The neural network is trained on images reconstructed from both complete and incomplete data.

Abstract

Image reconstruction with under-sampled data is usually achieved by an iterative algorithm, which minimizes an objective function. The objective function commonly contains a data fidelity term and one or more Bayesian terms. A popular Bayesian term is the total variation (TV) norm of the image.

This paper suggests an addition Bayesian term that is generated by a neural network. This neural network is essentially a classifier. This classifier can recognize the artifacts caused by the incomplete data. This classifier is trained by patient images reconstructed by complete and incomplete data sets. This newly introduced Bayesian term is referred to as the CNN score, which is a real number in (−∞, ∞).

Patient studies show the good correlation between the CNN score and the severeness of the artifacts due to the incomplete measurements.

A neural network can extract features from images that are suffering from incomplete measurements and convert the features into a CNN score. An iterative image reconstruction algorithm can be developed to minimize this CNN score to suppress the artifacts in the reconstructed image.

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