Ultrasound Diagnosis of Hepatocellular Carcinoma: Is the Future Defined by Artificial Intelligence?

Introduction

Technological progress and the development of complex mathematical models that allow the analysis of large and partially unstructured data have led to the rapid development of artificial intelligence (AI) since the 2010 s [1]. New AI applications, such as the recent “chatbot” ChatGPT, regularly attract a great deal of media attention with headlines ranging from euphoric to critical. As a result, the population developed specific expectations of the benefits, but also concerns about the potential risks of AI. In a survey published in 2023 by the digital association Bitkom, 73 % of the 1007 people surveyed saw AI as an opportunity [2]. Two thirds wanted AI to be used when it would bring specific benefits, for example in medicine or transportation. 14 % and 10 % of respondents saw AI rather or exclusively as a risk, respectively. The majority of respondents assumed that AI would noticeably change our society in the coming years. These survey results impressively show how much is already expected of AI. And indeed, AI accompanies us consciously or unconsciously in many everyday situations. There are also several examples in clinical medicine, e. g., in the automated evaluation of ECGs, differential blood counts, etc. [1]. Intensive research has been carried out into the possible use of AI in medical imaging since its beginnings over 80 years ago. In addition to approaches for image optimization, this primarily includes automated diagnosis for disease detection and classification as well as therapeutic monitoring. Enormous progress has been made in the field of imaging in recent years through the use of deep learning (DL) technologies. In contrast to classic forms of machine learning (ML), DL is based on neural networks in which several network levels are linked together [3]. Convolutional neural networks (CNNs) are frequently used in the field of image recognition. These are characterized by a hierarchical recognition of image patterns by the different network levels [3]. If initial structures such as corners, edges, or simple shapes are recognized, the linking of these simple structures in the deeper network levels enables the classification of complex structures such as malignancies in clinical imaging. In addition to better predictability, CNNs are more flexible than traditional ML. Furthermore, the time-consuming extraction of diagnostically relevant image information (“feature extraction”), which is necessary with classic ML, is no longer required, as image features are recognized independently by CNNs.

Particularly in radiological imaging (including computed tomography and magnetic resonance imaging), CNNs have achieved outstanding results in clinical diagnostics and therapeutic monitoring. These have already led to various commercially available and approved AI applications in the field of oncological imaging, among others [4] ([Fig. 1]).

Fig. 1 Use of artificial intelligence (AI) in oncological imaging. Previous studies have investigated the possible use of AI in the detection, characterization, and therapeutic monitoring of oncological diseases. Illustration modified according to El Naqa et al., Br J Radiol, 2020 [5].

Compared to radiological imaging, the use of AI in sonographic imaging involves particular challenges [6]. Due to the examiner dependency in sonographic image acquisition, possible image material for training AI generally has a higher variability. The representation of identical findings in different scanning planes can, for example, lead to considerable differences in image interpretation and thus make correct classification by the AI more difficult. Similar effects can be caused by differences in the devices or transducers used.

In the following, we will discuss the extent to which these effects impact the use of AI in sonography, where AI currently stands in sonography, what limitations are to be expected, and what steps are needed next to enable the successful translation of AI into clinical sonography, using the example of the sonographic diagnosis of hepatocellular carcinoma (HCC).

Publication History

Article published online:
01 February 2024

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