High-resolution myocardial T  1 mapping using single-shot inversion recovery fast low-angle shot MRI with radial undersampling and iterative reconstruction

Abstract

Objective:To develop a novel method for rapid myocardial T1 mapping at high spatial resolution.Methods:The proposed strategy represents a single-shot inversion recovery experiment triggered to early diastole during a brief breath-hold. The measurement combines an adiabatic inversion pulse with a real-time readout by highly undersampled radial FLASH, iterative image reconstruction and T1 fitting with automatic deletion of systolic frames. The method was implemented on a 3-T MRI system using a graphics processing unit-equipped bypass computer for online application. Validations employed a T1 reference phantom including analyses at simulated heart rates from 40 to 100 beats per minute. In vivo applications involved myocardial T1 mapping in short-axis views of healthy young volunteers.Results:At 1-mm in-plane resolution and 6-mm section thickness, the inversion recovery measurement could be shortened to 3 s without compromising T1 quantitation. Phantom studies demonstrated T1 accuracy and high precision for values ranging from 300 to 1500 ms and up to a heart rate of 100 beats per minute. Similar results were obtained in vivo yielding septal T1 values of 1246 ± 24 ms (base), 1256 ± 33 ms (mid-ventricular) and 1288 ± 30 ms (apex), respectively (mean ± standard deviation, n = 6).Conclusion:Diastolic myocardial T1 mapping with use of single-shot inversion recovery FLASH offers high spatial resolution, T1 accuracy and precision, and practical robustness and speed.Advances in knowledge:The proposed method will be beneficial for clinical applications relying on native and post-contrast T1 quantitation.

Model‐based T1 mapping with sparsity constraints using single‐shot inversion‐recovery radial FLASH

“…T 1 mapping approaches typically are based on an inversion‐recovery (IR) Look‐Locker sequence with quantitations performed as a post‐processing step by pixel‐wise fitting and suitable corrections for multiple radiofrequency (RF) excitations . Recent improvements toward single‐shot T 1 mapping exploit advances in real‐time MRI , which define the IR readout by a series of highly undersampled radial fast low‐angle shot (FLASH) images with nonlinear inversion (NLINV) reconstruction. On the other hand, various acceleration techniques for MRI parameter mapping have been proposed that include a priori information about the signal model to constrain the parameter space during reconstruction.…”

Simultaneous multislice imaging for native myocardial T1 mapping: Improved spatial coverage in a single breath-hold

“…Image acceleration techniques, such as parallel imaging, are frequently used in breath‐held myocardial T 1 mapping to provide sufficient spatial resolution in the single‐shot acquisitions during the brief diastolic quiescence . Compressed sensing has also been used to improve spatial resolution in T 1 mapping in a single breath‐hold . However, these approaches, as commonly used, do not affect the coverage or the total acquisition time and thus do not change the breath‐hold duration.…”

Whole‐heart T1 mapping using a 2D fat image navigator for respiratory motion compensation

“…To obtain similar image quality with the fat‐iNAV as with the gated NAV scans, more advanced motion correction techniques such as affine or non‐rigid correction will be required, which would better approximate the respiratory motion of the heart . Alternatively, more motion tolerant k‐space trajectories could be used for T 1 mapping such as radial acquisitions . This could also permit discarding a small subset of the most motion corrupted k‐space data without introducing detrimental undersampling artifacts.…”

“…[25][26][27] Alternatively, more motion tolerant k-space trajectories could be used for T 1 mapping such as radial acquisitions. [28][29][30] This could also permit discarding a small subset of the most motion corrupted k-space data without introducing detrimental undersampling artifacts.…”