Comparison of breath-hold, respiratory navigated and free-breathing MR elastography of the liver

Abstract

$\textit{Purpose:}$ Hepatic magnetic resonance elastography (MRE) is currently a breath-hold imaging technique. Patients with chronic liver disease can have comorbidities that limit their ability to breath-hold (BH) for the required acquisition time. Our aim was to evaluate whether stiffness measurements obtained from a navigator-triggered MRE acquisition are comparable to standard expiratory breath-hold, inspiratory breath-hold or free-breathing in healthy participants. $\textit{Materials and methods:}$ Twelve healthy participants were imaged using the four methods on a clinical 1.5 T MR system equipped with a product MRE system. Mean liver stiffness, and measurable area of stiffness (with a confidence threshold >95%) were compared between sequences using the concordance correlation coefficient. Repeatability of each sequence between two acquisitions was also assessed. $\textit{Results:}$ The standard BH expiratory technique had high concordance with the navigated technique (r = 0.716), and low concordance with the BH inspiration (r = 0.165) and free-breathing (r = 0.105) techniques. The navigator-triggered technique showed no statistical difference in measurable area of liver or in repeatability compared with the standard expiratory acquisition (p = 0.997 and p = 0.407 respectively). The free-breathing technique produced less measurable liver area and was less repeatable than the alternative techniques. The increase in acquisition time for navigator techniques was 3 min 6 s compared to standard expiratory breath-hold. $\textit{Conclusion:}$ Navigator-based hepatic MRE measurements are comparable to the reference standard expiratory breath-hold acquisition in healthy participants.