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

Abstract

Purpose To combine a 3D saturation-recovery-based myocardial T1 mapping (3D SASHA) sequence with a 2D image navigator with fat excitation (fat-iNAV) to allow 3D T1 maps with 100% respiratory scan efficiency and predictable scan time. Methods Data from T1 phantom and 10 subjects were acquired at 1.5T. For respiratory motion compensation, a 2D fat-iNAV was acquired before each 3D SASHA k-space segment to correct for 2D translational motion in a beat-to-beat fashion. The effect of the fat-iNAV on the 3D SASHA T1 estimation was evaluated on the T1 phantom. For 3 representative subjects, the proposed free-breathing 3D SASHA with fat-iNAV was compared to the original implementation with the diaphragmatic navigator. The 3D SASHA with fat-iNAV was compared to the breath-hold 2D SASHA sequence in terms of accuracy and precision. Results In the phantom study, the Bland-Altman plot shows that the 2D fat-iNAVs does not affect the T1 quantification of the 3D SASHA acquisition (0 ± 12.5 ms). For the in vivo study, the 2D fat-iNAV permits to estimate the respiratory motion of the heart, while allowing for 100% scan efficiency, improving the precision of the T1 measurement compared to non-motion-corrected 3D SASHA. However, the image quality achieved with the proposed 3D SASHA with fat-iNAV is lower compared to the original implementation, with reduced delineation of the myocardial borders and papillary muscles. Conclusions We demonstrate the feasibility to combine the 3D SASHA T1 mapping imaging sequence with a 2D fat-iNAV for respiratory motion compensation, allowing 100% respiratory scan efficiency and predictable scan time.

Faster 3D saturation-recovery based myocardial T1 mapping using a reduced number of saturation points and denoising

“…Nevertheless, it was still dependent on the efficiency of the diaphragmatic navigator and its unpredictable scan time, which can severely drop in patients with irregular breathing patterns. Alternative motion compensation techniques, such as image-based navigation and self-navigation [25][26][27][28], will be investigated in future studies to achieve 100% respiratory scan efficiency and consequently to further accelerate the scan, which can provide more comfort to the patient and reduce the risk of introducing additional bulk motion artifacts associated with long scans.…”

3D whole‐heart isotropic‐resolution motion‐compensated joint T1/T2 mapping and water/fat imaging

“…Recently, 3D free breathing T 1 and T 2 mapping techniques have been proposed to overcome the need for breath-holds, increase spatial resolution, and minimize through-plane motion artifacts. [14][15][16][17][18][19][20][21][22][23] Some of these approaches were designed for postcontrast application; thus, a direct extension to precontrast acquisition would not be straightforward. 14,15 Acquisition of 3D free-breathing native T 1 or T 2 maps has been demonstrated using 1D diaphragmatic navigators, but this approach leads to long and unpredictable scan time, limiting spatial resolution and clinical adoption.…”

“…Recently, 3D free breathing T 1 and T 2 mapping techniques have been proposed to overcome the need for breath‐holds, increase spatial resolution, and minimize through‐plane motion artifacts 14‐23 . Some of these approaches were designed for postcontrast application; thus, a direct extension to precontrast acquisition would not be straightforward 14,15 .…”

“…14,15 Acquisition of 3D free-breathing native T 1 or T 2 maps has been demonstrated using 1D diaphragmatic navigators, but this approach leads to long and unpredictable scan time, limiting spatial resolution and clinical adoption. 14,16,17,19 1D and 2D self-navigation or fat image navigators enabled the acquisition of 3D T 1 or T 2 maps with 100% respiratory scan efficiency 18,21,24 ; however, recovery heart beats for magnetization recovery affect the total scan time, leading to a tradeoff between spatial resolution 18 and acquisition time. 21 A matching approach for T 2 map generation was adopted to avoid the need of pauses for magnetization recovery, enabling the acquisition of high-resolution 3D T 2 maps within a scan time of ~10 min or less, 22,23 relying on 2D image navigators and undersampled acquisition; however, these approaches do not provide T 1 quantification.…”

Single breath-hold saturation recovery 3D cardiac T1 mapping via compressed SENSE at 3T

“…They require navigator-triggered free-breathing and, therefore, rely on the respiratory navigation performance to achieve good image quality and acceptable acquisition time. Acquisition time is nevertheless in the range of minutes, even when denoising and optimization techniques are used [ 13 , 14 ]. Such long acquisition time compromises the feasibility of T1 mapping during contrast equilibrium and reduce clinical applicability.…”