Free-running 3D whole heart myocardial T1 mapping with isotropic spatial resolution.

Haikun Qi,Olivier Jaubert,Claudia Prieto,Aurelien Bustin,Huijun Chen,René Botnar,Gastao Cruz

doi:10.1002/mrm.27811

Haikun Qi, Olivier Jaubert + Show 5 more

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https://doi.org/10.1002/mrm.27811

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Abstract

PurposeTo develop a free‐running (free‐breathing, retrospective cardiac gating) 3D myocardial T1 mapping with isotropic spatial resolution.MethodsThe free‐running sequence is inversion recovery (IR)‐prepared followed by continuous 3D golden angle radial data acquisition. 1D respiratory motion signal is extracted from the k‐space center of all spokes and used to bin the k‐space data into different respiratory states, enabling estimation and correction of 3D translational respiratory motion, whereas cardiac motion is recorded using electrocardiography and synchronized with data acquisition. 3D translational respiratory motion compensated T1 maps at diastole and systole were generated with 1.5 mm isotropic spatial resolution with low‐rank inversion and high‐dimensionality patch‐based undersampled reconstruction. The technique was validated against conventional methods in phantom and 9 healthy subjects.ResultsPhantom results demonstrated good agreement (R2 = 0.99) of T1 estimation with reference method. Homogeneous systolic and diastolic 3D T1 maps were reconstructed from the proposed technique. Diastolic septal T1 estimated with the proposed method (1140 ± 36 ms) was comparable to the saturation recovery single‐shot acquisition (SASHA) sequence (1153 ± 49 ms), but was higher than the modified Look‐Locker inversion recovery (MOLLI) sequence (1037 ± 33 ms). Precision of the proposed method (42 ± 8 ms) was comparable to MOLLI (41 ± 7 ms) and improved with respect to SASHA (87 ± 19 ms).ConclusionsThe proposed free‐running whole heart T1 mapping method allows for reconstruction of isotropic resolution 3D T1 maps at different cardiac phases, serving as a promising tool for whole heart myocardial tissue characterization.

Highlights

To address the current technical challenges of myocardial T1 mapping, we propose a free‐running 3D whole heart T1 mapping technique with high isotropic spatial resolution (1.5 mm3), which is able to provide images in any desired orientation
Where ||·||F and ||·||* denote the Frobenius norm and nuclear norm respectively; I is√the compressed T1 image series to be reconstructed; E = DAUrFS is the encoding operator, with S being sensitivity maps, F being Fourier transform, Ur being the low‐rank operator obtained by truncating the singular value decomposition (SVD) of a dictionary generated by Bloch simulation,[20] A being the convolutional gridding operator, transforming Cartesian data back to 3D radial, and D being the non‐Cartesian density compensation function; K is the undersampled data; Pp(·) is the patch selection operator at pixel p of a 3D multi‐contrast image set
No significant differences were found between the diastolic and systolic T1 values estimated with the proposed technique in most of the American Heart Association (AHA) segments, except for the inferior segments in the apical and mid ventricular slices, and the inferoseptal segment in the basal slice, with significantly longer T1 values in diastole than in systole

Summary

Funding information

Purpose: To develop a free‐running (free‐breathing, retrospective cardiac gating) 3D myocardial T1 mapping with isotropic spatial resolution. 3D translational respiratory motion compensated T1 maps at diastole and systole were generated with 1.5 mm isotropic spatial resolution with low‐rank inversion and high‐dimensionality patch‐based undersampled reconstruction. Homogeneous systolic and diastolic 3D T1 maps were reconstructed from the proposed technique. Diastolic septal T1 estimated with the proposed method (1140 ± 36 ms) was comparable to the saturation recovery single‐shot acquisition (SASHA) sequence (1153 ± 49 ms), but was higher than the modified Look‐Locker inversion recovery (MOLLI) sequence (1037 ± 33 ms). Conclusions: The proposed free‐running whole heart T1 mapping method allows for reconstruction of isotropic resolution 3D T1 maps at different cardiac phases, serving as a promising tool for whole heart myocardial tissue characterization

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