T1 measurements in the human myocardium: The effects of magnetization transfer on the SASHA and MOLLI sequences
Article first published online: 15 JUL 2013
Copyright © 2013 Wiley Periodicals, Inc.
Magnetic Resonance in Medicine
Volume 70, Issue 3, pages 664–670, September 2013
How to Cite
Robson, M. D., Piechnik, S. K., Tunnicliffe, E. M. and Neubauer, S. (2013), T1 measurements in the human myocardium: The effects of magnetization transfer on the SASHA and MOLLI sequences. Magn Reson Med, 70: 664–670. doi: 10.1002/mrm.24867
- Issue published online: 27 AUG 2013
- Article first published online: 15 JUL 2013
- Manuscript Accepted: 11 JUN 2013
- Manuscript Revised: 17 MAY 2013
- Manuscript Received: 13 APR 2013
- MRC. Grant Number: G0900883 and G0700796
- National Institute for Health Research (NIHR) Oxford Biomedical Research Centre based at The Oxford University Hospitals Trust at the University of Oxford
- T1 mapping;
- cardiac MRI;
- tissue characterization;
- magnetization transfer
Quantitative mapping of the native T1 of the heart using the modified look-locker inversion recovery (MOLLI) technique provides high quality diagnostic information without requiring contrast agents. Previous work has considered the effects of T2 relaxation on MOLLI T1 measurements, finding that the T1 measured by MOLLI is biased, and that Saturation-recovery single-Shot Acquisition generates a more precise T1. However, despite detailed experiments and simulation the exact relaxation times observed in vivo remain unexplained, but might be due to magnetization transfer (MT).
We used an MT simulation based on the Bloch-McConnell equations to evaluate the most common MOLLI and saturation-recovery single-shot acquisition sequence variants.
For myocardial tissue we find that the T1 measured by saturation-recovery single-shot acquisition is insensitive to MT and T2, whereas MT reduces the T1 measured by MOLLI (>10%) in addition to the effects due to T2 relaxation.
The consequences of this T1 underestimation by MOLLI are relevant. Increases in the actual T1 and T2 and decreases in MT will all result in an increase in T1 measured by MOLLI. Myocardial infarction demonstrates increased native T1 and T2 and decreased MT, indicating that these biases enhance the sensitivity of MOLLI to detect this and possibly other cardiovascular disease states. Magn Reson Med 70:664–670, 2013. © 2013 Wiley Periodicals, Inc.