Multiparametric quantitative magnetic-resonance imaging mapping for the non-invasive assessment of liver fibrosis and disease severity

Abstract

Despite the global burden and clinical importance of CLDs, non-invasive, reliable, accurate, and reproducible imaging-based biomarkers for comprehensive assessment and monitoring of liver disease severity, periprocedural planning, and prognosis estimation are still insufficient. Therefore, active research in this field continues. <br /> In this cumulative habilitation thesis, we presented and discussed studies investigating the diagnostic utility of MRI-derived quantitative mapping parameters for the assessment of liver fibrosis and liver cirrhosis severity. Moreover, we proposed a simple to obtain and reliable method for ECV calculation without the need for hematocrit sampling. <br /> The high diagnostic utility of T1 mapping with the calculation of ECV was demonstrated for the assessment and differentiation between different fibrosis stages in patients with AIH and PSC. The results of these studies support the clinical application of quantitative mapping parameters in these specific patient cohorts for the non-invasive assessment and monitoring of liver fibrosis. Furthermore, we expanded the clinical application of quantitative mapping techniques in patients with CLDs demonstrating their value and high diagnostic performance for the assessment of liver cirrhosis severity as defined by the Child-Pugh score. In particular, hepatic ECV revealed high diagnostic performance in discrimination between different Child-Pugh classes of liver cirrhosis. Hepatic ECV also outperformed other mapping parameters and clinical markers/scores in differentiation between different Child-Pugh classes of liver cirrhosis. Additionally, not only hepatic mapping parameters were shown to be useful for the assessment of liver cirrhosis severity, but splenic parameters were as well. In particular, we demonstrated and discussed significant correlations between splenic ECV and invasive portal pressure measurements. <br /> Interestingly, among all quantitative mapping parameters being under investigation in the presented studies, hepatic and splenic ECV have proven to be more accurate and reliable biomarkers. They outperformed native T1, post-contrast T1, and T2 in both staging liver fibrosis and assessing liver cirrhosis severity. Further, the results of our studies suggest that mapping parameters may overcome the limitation of conventional morphological imaging and provide valuable information beyond morphology in a single imaging setting. Further prospective studies are needed to establish the results of these studies and to ensure further development, validation and implementation of non-invasive imaging-based parameters into routine clinical practice. <br /> Last but not least, the proposed method of synthetic ECV calculation without hematocrit sampling was shown to be reliable, accurate, and reproducible. The use of synthetic ECV may overcome a limitation related to hematocrit sampling and allow for broader ECV implementation into routine clinical practice for hepatic applications. <br /> In summary, this cumulative work broadens our understanding and knowledge of clinical applications of quantitative MRI biomarkers for the assessment of liver disease severity in patients with CLD, including autoimmune liver diseases, and highlights the importance of novel imaging-based biomarkers in the detection and characterization of liver fibrosis and liver cirrhosis severity. Therefore, based on the finding of our studies the clinical application of quantitative mapping techniques for hepatic applications should be expanded.