Saturation recovery single-shot acquisition and saturation pulse prepared heart rate independent inversion recovery have superior accuracy, inferior precision, and similar reproducibility compared ... PurposeTo compare accuracy, precision, and reproducibility of four commonly used myocardial T1 mapping sequences: modified Look-Locker inversion recovery (MOLLI), shortened MOLLI (ShMOLLI), saturat...

Purpose: To develop arrhythmia‐insensitive inversion recovery sequences for improved visualization of myocardial scar and quantification of diffuse fibrosis.Methods: A novel preparation pre‐pulse, called saturation pulse prepared heart‐rate‐independent inversion recovery, is introduced, which consists of a combination of saturation and inversion pulses to remove the magnetization history in each heartbeat in late gadolinium enhancement (LGE) imaging and eliminate the need for rest periods in T₁ mapping. The proposed LGE and T₁ mapping sequences were evaluated against conventional LGE and modified Look‐Locker inversion sequences using numerical simulations, phantom and imaging in healthy subjects and patients with suspected or known cardiovascular disease.Results: Simulations and phantom experiments show that the saturation pulse prepared heart‐rate‐independent inversion recovery pre‐pulse in LGE reduces ghosting artifacts and results in perfect nulling of the healthy myocardium in the presence of arrhythmia. In T₁ mapping, saturation pulse prepared heart‐rate‐independent inversion recovery results in (a) reduced scan time (17 vs. 9 heartbeats), (b) insensitivity to heart rate for long T₁, and (c) increased signal homogeneity for short T₁. LGE images in a patient in atrial fibrillation during the scan show improved myocardial nulling. In vivo T₁ maps demonstrate increased signal homogeneity in blood pools and myocardium.Conclusion: The proposed sequences are insensitive to heart rate variability, yield improved LGE images in the presence of arrhythmias, as well as T₁ mapping with shorter scan times. Magn Reson Med 71:1024–1034, 2014. © 2013 Wiley Periodicals, Inc.

Quantitative myocardial and blood T₁ have recently achieved clinical utility in numerous pathologies, as they provide non-invasive tissue characterization with the potential to replace invasive biopsy. Native T₁ time (no contrast agent), changes with myocardial extracellular water (edema, focal or diffuse fibrosis), fat, iron, and amyloid protein content. After contrast, the extracellular volume fraction (ECV) estimates the size of the extracellular space and identifies interstitial disease. Spatially resolved quantification of these biomarkers (so-called T₁ mapping and ECV mapping) are steadily becoming diagnostic and prognostically useful tests for several heart muscle diseases, influencing clinical decision-making with a pending second consensus statement due mid-2017. This review outlines the physics involved in estimating T₁ times and summarizes the disease-specific clinical and research impacts of T₁ and ECV to date. We conclude by highlighting some of the remaining challenges such as their community-wide delivery, quality control, and standardization for clinical practice.

Purpose: To develop a novel pulse sequence for free‐breathing, multislice, native myocardial T₁ mapping.Methods: The slice‐interleaved T₁ (STONE) sequence consists of multiple sets of single‐shot images of different slices, acquired after a single nonselective inversion pulse. Each slice is only selectively excited once after each inversion pulse to allow sampling of the unperturbed longitudinal magnetization in the adjacent slices. For respiratory motion, a prospective slice‐tracking respiratory navigator is used to decrease through‐plane motion followed by a retrospective image registration to reduce in‐plane motion. STONE T₁ maps were calculated using both a two‐parameter and three‐parameter fit model. The accuracy and precision of the STONE sequence for different T₁, T₂, and inversion pulse efficiency were studied using numerical simulations and phantom experiments. T₁ maps from 14 subjects were acquired with the STONE sequence and T₁s were compared to the MOdified Look‐Locker Inversion recovery sequence (MOLLI).Results: In numerical simulations and phantom experiments, the STONE sequence using a two‐parameter fit model yields more accurate T₁ times compared to MOLLI, with similar high precision. The three‐parameter fit model further improves the accuracy, but with a reduced precision. The native myocardial T₁ times were higher in the STONE sequence using two‐ or three‐parameter fit compared to MOLLI. The standard deviation of the T₁ times was lower in the STONE T₁ maps with a two‐parameter fit compared with MOLLI or a three‐parameter fit.Conclusion: The STONE sequence allows accurate and precise quantification of native myocardial T₁ times with the additional benefit of covering the entire ventricle. Magn Reson Med 74:115–124, 2015.

Purpose: To develop an improved T₂ prepared (T₂prep) balanced steady‐state free‐precession (bSSFP) sequence and signal relaxation curve fitting method for myocardial T₂ mapping.Methods: Myocardial T₂ mapping is commonly performed by acquisition of multiple T₂prep bSSFP images and estimating the voxel‐wise T₂ values using a two‐parameter fit for relaxation. However, a two‐parameter fit model does not take into account the effect of imaging pulses in a bSSFP sequence or other imperfections in T₂prep RF pulses, which may decrease the robustness of T₂ mapping. Therefore, we propose a novel T₂ mapping sequence that incorporates an additional image acquired with saturation preparation, simulating a very long T₂prep echo time. This enables the robust estimation of T₂ maps using a 3‐parameter fit model, which captures the effect of imaging pulses and other imperfections. Phantom imaging is performed to compare the T₂ maps generated using the proposed 3‐parameter model with the conventional two‐parameter model, as well as a spin echo reference. In vivo imaging is performed on eight healthy subjects to compare the different fitting models.Results: Phantom and in vivo data show that the T₂ values generated by the proposed 3‐parameter model fitting do not change with different choices of the T₂prep echo times, and are not statistically different than the reference values for the phantom (P = 0.10 with three T₂prep echoes). The two‐parameter model exhibits dependence on the choice of T₂prep echo times and are significantly different than the reference values (P = 0.01 with three T₂prep echoes).Conclusion: The proposed imaging sequence in combination with a three‐parameter model allows accurate measurement of myocardial T₂ values, which is independent of number and duration of T₂prep echo times. Magn Reson Med 74:93–105, 2015.