Multi-structure bone segmentation in pediatric MR images with combined regularization from shape priors and adversarial network

TL;DR

This paper introduces a novel pre-trained regularized convolutional network for pediatric bone segmentation in MR images, combining shape priors and adversarial regularization to improve accuracy on scarce datasets.

Contribution

It proposes a new optimization scheme with shape prior and adversarial regularization, enhancing segmentation performance on limited pediatric MR data.

Findings

Achieved comparable or better segmentation metrics than existing methods.

Effectively integrated into various bone segmentation strategies.

Improved prediction accuracy using pre-trained models on large non-medical datasets.

Abstract

Morphological and diagnostic evaluation of pediatric musculoskeletal system is crucial in clinical practice. However, most segmentation models do not perform well on scarce pediatric imaging data. We propose a new pre-trained regularized convolutional encoder-decoder network for the challenging task of segmenting heterogeneous pediatric magnetic resonance (MR) images. To this end, we have conceived a novel optimization scheme for the segmentation network which comprises additional regularization terms to the loss function. In order to obtain globally consistent predictions, we incorporate a shape priors based regularization, derived from a non-linear shape representation learnt by an auto-encoder. Additionally, an adversarial regularization computed by a discriminator is integrated to encourage precise delineations. The proposed method is evaluated for the task of multi-bone segmentation on two scarce pediatric imaging datasets from ankle and shoulder joints, comprising pathological as well as healthy examinations. The proposed method performed either better or at par with previously proposed approaches for Dice, sensitivity, specificity, maximum symmetric surface distance, average symmetric surface distance, and relative absolute volume difference metrics. We illustrate that the proposed approach can be easily integrated into various bone segmentation strategies and can improve the prediction accuracy of models pre-trained on large non-medical images databases. The obtained results bring new perspectives for the management of pediatric musculoskeletal disorders.