Free‐breathing 3D cardiac T1 mapping with transmit B1 correction at 3T. Issue 4 (23rd November 2021)

• Record Type: Journal Article
• Authors: Han, Paul Kyu; Marin, Thibault; Djebra, Yanis; Landes, Vanessa; Zhuo, Yue; El Fakhri, Georges; Ma, Chao
• Is Part Of: Magnetic resonance in medicine. Volume 87:Issue 4(2022)
• Page Start: 1832
• Page End: 1845
• Publication Date: 2021-11-23
• Subjects: cardiac T1 mapping -- free‐breathing -- low‐rank -- myocardial T1 mapping -- spoiled gradient‐echo -- transmit B1 inhomogeneity; Nuclear magnetic resonance -- Periodicals; Electron paramagnetic resonance -- Periodicals; 616.07548
• DOI: 10.1002/mrm.29097
• Languages: English
• ISSNs: 0740-3194

Abstract

Abstract : Purpose: To develop a cardiac T1 mapping method for free‐breathing 3D T1 mapping of the whole heart at 3 T with transmit B1 ( B 1 + ) correction. Methods: A free‐breathing, electrocardiogram‐gated inversion‐recovery sequence with spoiled gradient‐echo readout was developed and optimized for cardiac T1 mapping at 3 T. High‐frame‐rate dynamic images were reconstructed from sparse (k, t)‐space data acquired along a stack‐of‐stars trajectory using a subspace‐based method for accelerated imaging. Joint T1 and flip‐angle estimation was performed in T1 mapping to improve its robustness to B 1 + inhomogeneity. Subject‐specific timing of data acquisition was used in the estimation to account for natural heart‐rate variations during the imaging experiment. Results: Simulations showed that accuracy and precision of T1 mapping can be improved with joint T1 and flip‐angle estimation and optimized electrocardiogram‐gated spoiled gradient echo–based inversion‐recovery acquisition scheme. The phantom study showed good agreement between the T1 maps from the proposed method and the reference method. Three‐dimensional cardiac T1 maps (40 slices) were obtained at a 1.9‐mm in‐plane and 4.5‐mm through‐plane spatial resolution from healthy subjects (n = 6) with an average imaging time of 14.2 ± 1.6 minutes (heartbeat rate: 64.2 ± 7.1 bpm), showing myocardial T1 values comparable to those obtained from modified Look‐Locker inversion recovery. The proposed method generated B 1 + maps with spatially smooth variation showing 21%–32% and 11%–15% variations across the septal–lateral and inferior–anterior regions of the myocardium in the left ventricle. Conclusion: The proposed method allows free‐breathing 3D T1 mapping of the whole heart with transmit B1 correction in a practical imaging time.