Free-breathing MRI techniques for fat and R2* quantification in the liver.

Objective: To review the recent advancements in free-breathing MRI techniques for proton-density fat fraction (PDFF) and R₂* quantification in the liver, and discuss the current challenges and future opportunities.

Materials and methods: This work focused on recent developments of different MRI pulse sequences, motion management strategies, and reconstruction approaches that enable free-breathing liver PDFF and R₂* quantification.

Results: Different free-breathing liver PDFF and R₂* quantification techniques have been evaluated in various cohorts, including healthy volunteers and patients with liver diseases, both in adults and children. Initial results demonstrate promising performance with respect to reference measurements. These techniques have a high potential impact on providing a solution to the clinical need of accurate liver fat and iron quantification in populations with limited breath-holding capacity.

Discussion: As these free-breathing techniques progress toward clinical translation, studies of the linearity, bias, and repeatability of free-breathing PDFF and R₂* quantification in a larger cohort are important. Scan acceleration and improved motion management also hold potential for further enhancement.