A segmented modified look-locker inversion recovery (MOLLI) sequence for high heart rate T1 mapping of mice
KeywordsHigh Heart Rate Inversion Pulse Mouse Imaging British Heart Foundation Myocardial Tissue Characterization
Quantitative T1 mapping provides myocardial tissue characterization for assessment of various cardiomyopathies. The Modified Look-locker (MOLLI) sequence is widely used for mapping the T1quantification, where multiple single-shot images are acquired along the T1 recovery curve after an inversion pulse. However, single-shot imaging becomes infeasible for mouse imaging at high heart rates due to motion artifacts and requirements of resolution/coverage. Additionally, typical MOLLI sampling schemes  (3-3-5) and the pauses between blocks have to be adapted to the high heart rates in mice. In this work, we propose a segmented acquisition scheme for T1 mapping of mouse at high heart rates. After an initial inversion pulse we acquire segments for 20 images in subsequent heartbeats followed by 20 pause heartbeats to allow for full magnetization recovery. The complete k-space is acquired in this fashion over 5 segments per image. Experiments were performed with a T1 phantom by simulating high heart rates to evaluate the accuracy of the proposed sequence. Proof of concept T1 maps were also acquired in one healthy mouse.
We demonstrate the feasibility of T1 mapping for high heart rates observed in mice. The proposed segmented MOLLI sequence provides accurate T1 estimates for short T1 values, while an underestimation is observed for higher T1 values, as typical of MOLLI.
British Heart Foundation : RG/12/1/29262.
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