Published Online:https://doi.org/10.1148/rg.2017160130

Machine learning is a powerful technique for recognizing patterns on medical images; however, it must be used with caution because it can be misused if the strengths and weaknesses of this technology are not understood.

Machine learning is a technique for recognizing patterns that can be applied to medical images. Although it is a powerful tool that can help in rendering medical diagnoses, it can be misapplied. Machine learning typically begins with the machine learning algorithm system computing the image features that are believed to be of importance in making the prediction or diagnosis of interest. The machine learning algorithm system then identifies the best combination of these image features for classifying the image or computing some metric for the given image region. There are several methods that can be used, each with different strengths and weaknesses. There are open-source versions of most of these machine learning methods that make them easy to try and apply to images. Several metrics for measuring the performance of an algorithm exist; however, one must be aware of the possible associated pitfalls that can result in misleading metrics. More recently, deep learning has started to be used; this method has the benefit that it does not require image feature identification and calculation as a first step; rather, features are identified as part of the learning process. Machine learning has been used in medical imaging and will have a greater influence in the future. Those working in medical imaging must be aware of how machine learning works.

©RSNA, 2017

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Article History

Received: May 5 2016
Revision requested: July 27 2016
Revision received: Oct 28 2016
Accepted: Nov 4 2016
Published online: Feb 17 2017
Published in print: Mar 2017