Skeletal bone age prediction based on a deep residual network with spatial transformer

https://doi.org/10.1016/j.cmpb.2020.105754Get rights and content

Highlights

  • Clinicians predict bone age by manually reading X-ray hand bone images.

  • SVM automatic bone age assessment method has bone age prediction capability.

  • ST-ResNet network model is based on ResNet and spatial transformer.

  • ST-ResNet network model demonstrates better bone age prediction accuracy.

  • Deep learning can facilitate bone age detection more effectively.

Abstract

Objective

Bone age prediction can be performed by medical experts manually assessment of X-ray images of the hand bone. In practice, the workload is huge, resource consumption is large, measurement takes a long time, and it is easily influenced by human factors. As such, manual estimation of bone age takes a long time and the results fluctuate greatly depending on the proficiency of the radiologist.

Methods

The left-hand X-ray image data was identified and pre-processed. X-ray image analysis method using on deep neural network was used to automatically extract the key features of the left-hand joint bone age, and evaluation performance of the model was implemented.

Results

In this paper, the deep learning method can be used to obtain the X-ray bone image features, and the convolutional neural network is used to automatically assess the age of bone. The feature region extraction method based on deep learning can extract feature information with superior performance compared to the traditional image analysis technique. Based on the residual network (ResNet) model in the deep learning algorithm, the average absolute error of the age of bones detected by the bone age assessment model is 0.455 better than traditional methods and only end-to-end deep learning methods. When the learning rate is greater than 0.0005, the MAE of Inception Resnet v2 model is higher than most models. Accuracy of bone age prediction is as high as 97.6%.

Conclusion

In comparison with the traditional machine learning feature extraction technique, the convolutional neural network based on feature extraction has better performance in the bone age regression model, and further improves the accuracy of image-based age of bone assessment.

Introduction

In the medical field, human growth and development is mainly measured by the following types of 'ages', namely the chronological age and biological age. Among them, age of chronology is relatively simple, and is determined by the date of birth. The biological age mainly reflects the development of human beings, which is mainly determined by the age of teeth and bone age. Among them, the tooth age is the earliest used biological age indicator [1]. During the Roman Empire, eruption of second molar was used as the standard of service. Before the 19th century, the age of the teeth was widely accepted by medical scientists. However, in 1846, the British doctor by the name of Petro proposed that the eruption of specific teeth as the criterion for biological age is extremely imprecise [2]. Therefore, in 1886, Angererr [[22]] first proposed that the biological age of adolescents could be determined by hand bones. Compared with the dental age, the bone age shows the growth and development of whole-body bone of test subject, is more suitable as a criterion for determining the biological age.

Skeletal bone age prediction has been commonly used in clinical medicine, preventive medicine, biology, sports science, forensic anthropology and other fields. In the pediatric clinical, through the analysis of skeletal bone age, combined with physical examination and laboratory tests, it is possible to detect the causes of growth and disease in children in a timely manner, and timely take effective interventions to obtain a good prognosis [3].

With continuous innovation and computer technology, the application of computer technology has penetrated into various fields and has had a tremendous impact on people's lives. In medicine, incorporation of computer vision technique in image recognition and image understanding, bone age assessment technology has also been rapidly developed and improved.

Although the method based on deep learning has made great achievements in bone age prediction [[29]], it still faces considerable challenges. Among them, previous work focused on improving the prediction accuracy, and then in the real scene, various reasons may lead to poor quality of X-ray images, but the existing work has ignored this point. In addition, compared with ordinary natural images, because medical image acquisition is more costly and marking requires professional radiologists, so the dataset dedicated to bone age prediction and with high-quality labels is very limited. As such, this poses a challenge to the training of neural networks [4].

Compared with traditional simple learning [[30], [31], [32], [33]], the difference between deep learning is that the former uses a multi-layer network structure to learn the characteristics of the data autonomously, while the latter mostly needs to manually extract feature information. The features extracted manually are often not accurate enough or is unable to represent the essence of things well, and it is difficult to improve the learning effect. Neural network is a successful application of deep learning in the field of images, and so we use deep learning framework to predict bone age.

Section snippets

Image scaling

Images with inconsistent resolution are training samples that cannot be used as a classification model, so you first need to scale the image to a uniform size, where the original image in the dataset is uniformly scaled to 300 × 300 pixels resolution. This is because after the image is scaled, the feature information of the image is not greatly lost, and the feature extraction of the scaled image is not greatly affected, and the huge computational amount of the feature extraction process can be

Image scaling

First, the image pyramid is used to complete the scaling of the image. The image pyramid is composed of a plurality of sample images of the same image arranged in a pyramid form from bottom to top in descending order of resolution. The two common types of image pyramids are divided into Gaussian pyramids and Laplacian pyramids. This section uses the Gaussian pyramid to downsample the image, i.e. to create (i+1)-th layer from the i-th layer of the pyramid. To obtain (i+1)-th sampled image, the

Comparison between deep learning and traditional methods

Bone age studies range from early percentile methods, counting methods, GP mapping methods to recent CHN methods, TW3 methods, etc. [[12],[13]]. Currently, GP mapping is the most widely used, and radiologists usually treat patients' left wrist X. The results are affected by the level and ability of the reader and the consistency is poor. Compared with the G-P map method commonly used in hospitals, automatic image analysis has always been the goal of computer vision and radiology research.

Early

Conclusion

Skeletal bone age prediction is a common technique method usually based on determination of bone development characteristics to obtain a numerical assessment of human development. It is widely used in the prediction of teenagers' physical development, the discovery and prevention of diseases, sports selection, etc. It has important social significance. At present, the work in our country is mainly carried out by medical experts to read the X-ray hand bone images manually, but the workload is

Declaration of Competing Interest

The authors declare that there is no conflict of interests.

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