Free-breathing MOLLI: Application to myocardial T1 mapping

摘要

Purpose: Of the myocardial T1 mapping techniques, the modified Look-Locker inversion recovery (MOLLI) sequence is accurate and highly reproducible. The MOLLI sequence requires patients to hold their breath for 17 heartbeats during the scanning process to minimize respiratory motion-related artifacts. However, some patients are unable to hold their breath because of illness or limited breath-hold capacity. This study, therefore, aimed to develop a robust myocardial T1 mapping method based on the MOLLI sequence for patients unable to perform voluntary breath-holds. Methods: This study presents a free-breathing MOLLI (FB-MOLLI) sequence and an optimized reconstruction method to allow myocardial T1 mapping in vivo without breath-hold. Nine healthy volunteers participated in this study after providing institutionally approved consent. The FB-MOLLI sequence acquires 20 images within 29 heartbeats. The reconstruction program employs a two-step automatic image registration technique and an image selection method inspired by the self-gating cardiac imaging method. Results: Results indicate that the proposed reconstruction method increases the accuracy and reproducibility of free-breathing T1 measurements significantly (p 0.001). Conclusions: The FB-MOLLI method provides a robust tool for clinical application in free-breathing myocardial T1 mapping, and could greatly facilitate acquisition procedures during routine examinations.