Assessment of Liver Function With MRI: Where Do We Stand?

Abstract

Liver disease and hepatocellular carcinoma (HCC) have become a global health burden. For this reason, the determination of liver function plays a central role in the monitoring of patients with chronic liver disease or HCC. Furthermore, assessment of liver function is important, e.g., before surgery to prevent liver failure after hepatectomy or to monitor the course of treatment. Liver function and disease severity are usually assessed clinically based on clinical symptoms, biopsy, and blood parameters. These are rather static tests that reflect the current state of the liver without considering changes in liver function. With the development of liver-specific contrast agents for MRI, noninvasive dynamic determination of liver function based on signal intensity or using T1 relaxometry has become possible. The advantage of this imaging modality is that it provides additional information about the vascular structure, anatomy, and heterogeneous distribution of liver function. In this review, we summarized and discussed the results published in recent years on this technique. Indeed, recent data show that the T1 reduction rate seems to be the most appropriate value for determining liver function by MRI. Furthermore, attention has been paid to the development of automated tools for image analysis in order to uncover the steps necessary to obtain a complete process flow from image segmentation to image registration to image analysis. In conclusion, the published data show that liver function values obtained from contrast-enhanced MRI images correlate significantly with the global liver function parameters, making it possible to obtain both functional and anatomic information with a single modality.

Keywords: MRI; T1 relaxometry; artificial intelligence; deep learning; liver function.

Figure 1

Native and hepatobiliary-phase (HBP) T1 images of a healthy liver (56 years, male), a liver with an adenoma in liver segment VII (48 years, female), a cirrhotic liver (60 years, female), and a cirrhotic liver with a hepatocellular carcinoma (HCC) in liver segment VI (59 years, male) using gadoxetic acid as the contrast agent. The healthy liver clearly appears more hyperintense than the cirrhotic liver in the HBP image relative to the native image due to the ability of more functional hepatocytes to take up the contrast agent. Both adenoma and HCC appear hypointense in the HBP images.

Figure 2

Diagram illustrating the steps needed for automated image analysis to quantify liver function.