Dataset Information

3D SASHA myocardial T1 mapping with high accuracy and improved precision.

ABSTRACT:

Purpose

To improve the precision of a free-breathing 3D saturation-recovery-based myocardial T1 mapping sequence using a post-processing 3D denoising technique.

Methods

A T1 phantom and 15 healthy subjects were scanned on a 1.5?T MRI scanner using 3D saturation-recovery single-shot acquisition (SASHA) for myocardial T1 mapping. A 3D denoising technique was applied to the native T1-weighted images before pixel-wise T1 fitting. The denoising technique imposes edge-preserving regularity and exploits the co-occurrence of 3D spatial gradients in the native T1-weighted images by incorporating a multi-contrast Beltrami regularization. Additionally, 2D modified Look-Locker inversion recovery (MOLLI) acquisitions were performed for comparison purposes. Accuracy and precision were measured in the myocardial septum of 2D MOLLI and 3D SASHA T1 maps and then compared. Furthermore, the accuracy and precision of the proposed approach were evaluated in a standardized phantom in comparison to an inversion-recovery spin-echo sequence (IRSE).

Results

For the phantom study, Bland-Altman plots showed good agreement in terms of accuracy between IRSE and 3D SASHA, both on non-denoised and denoised T1 maps (mean difference -1.4?±?18.9 ms and -4.4?±?21.2 ms, respectively), while 2D MOLLI generally underestimated the T1 values (69.4?±?48.4 ms). For the in vivo study, there was a statistical difference between the precision measured on 2D MOLLI and on non-denoised 3D SASHA T1 maps (P?=?0.005), while there was no statistical difference after denoising (P?=?0.95).

Conclusion

The precision of 3D SASHA myocardial T1 mapping was substantially improved using a 3D Beltrami regularization based denoising technique and was similar to that of 2D MOLLI T1 mapping, while preserving the higher accuracy and whole-heart coverage of 3D SASHA.

SUBMITTER: Nordio G

PROVIDER: S-EPMC6424941 | biostudies-literature | 2019 Apr

REPOSITORIES: biostudies-literature

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Publications

3D SASHA myocardial T1 mapping with high accuracy and improved precision.

Nordio Giovanna G Bustin Aurélien A Henningsson Markus M Rashid Imran I Chiribiri Amedeo A Ismail Tevfik T Odille Freddy F Prieto Claudia C Botnar René Michael RM

Magma (New York, N.Y.) 20180906 2

<h4>Purpose</h4>To improve the precision of a free-breathing 3D saturation-recovery-based myocardial T1 mapping sequence using a post-processing 3D denoising technique.<h4>Methods</h4>A T1 phantom and 15 healthy subjects were scanned on a 1.5 T MRI scanner using 3D saturation-recovery single-shot acquisition (SASHA) for myocardial T1 mapping. A 3D denoising technique was applied to the native T1-weighted images before pixel-wise T1 fitting. The denoising technique imposes edge-preserving regular ...[more]

PMID: 30191345

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Project description:BACKGROUND:Cardiovascular magnetic resonance (CMR) T1? mapping can be used to detect ischemic or non-ischemic cardiomyopathy without the need of exogenous contrast agents. Current 2D myocardial T1? mapping requires multiple breath-holds and provides limited coverage. Respiratory gating by diaphragmatic navigation has recently been exploited to enable free-breathing 3D T1? mapping, which, however, has low acquisition efficiency and may result in unpredictable and long scan times. This study aims to develop a fast respiratory motion-compensated 3D whole-heart myocardial T1? mapping technique with high spatial resolution and predictable scan time. METHODS:The proposed electrocardiogram (ECG)-triggered T1? mapping sequence is performed under free-breathing using an undersampled variable-density 3D Cartesian sampling with spiral-like order. Preparation pulses with different T1? spin-lock times are employed to acquire multiple T1?-weighted images. A saturation prepulse is played at the start of each heartbeat to reset the magnetization before T1? preparation. Image navigators are employed to enable beat-to-beat 2D translational respiratory motion correction of the heart for each T1?-weighted dataset, after which, 3D translational registration is performed to align all T1?-weighted volumes. Undersampled reconstruction is performed using a multi-contrast 3D patch-based low-rank algorithm. The accuracy of the proposed technique was tested in phantoms and in vivo in 11 healthy subjects in comparison with 2D T1? mapping. The feasibility of the proposed technique was further investigated in 3 patients with suspected cardiovascular disease. Breath-hold late-gadolinium enhanced (LGE) images were acquired in patients as reference for scar detection. RESULTS:Phantoms results revealed that the proposed technique provided accurate T1? values over a wide range of simulated heart rates in comparison to a 2D T1? mapping reference. Homogeneous 3D T1? maps were obtained for healthy subjects, with septal T1? of 58.0 ± 4.1?ms which was comparable to 2D breath-hold measurements (57.6 ± 4.7?ms, P?=?0.83). Myocardial scar was detected in 1 of the 3 patients, and increased T1? values (87.4 ± 5.7?ms) were observed in the infarcted region. CONCLUSIONS:An accelerated free-breathing 3D whole-heart T1? mapping technique was developed with high respiratory scan efficiency and near-isotropic spatial resolution (1.7 × 1.7 × 2?mm3) in a clinically feasible scan time of ~?6 mins. Preliminary patient results suggest that the proposed technique may find applications in non-contrast myocardial tissue characterization.

Project description:BackgroundQuantitative relaxation time measurements by cardiovascular magnetic resonance (CMR) are of paramount importance in contrast-enhanced studies of experimental myocardial infarction. First, compared to qualitative measurements based on signal intensity changes, they are less sensitive to specific parameter choices, thereby allowing for better comparison between different studies or during longitudinal studies. Secondly, T1 measurements may allow for quantification of local contrast agent concentrations. In this study, a recently developed 3D T1 mapping technique was applied in a mouse model of myocardial infarction to measure differences in myocardial T1 before and after injection of a liposomal contrast agent. This was then used to assess the concentration of accumulated contrast agent.Materials and methodsMyocardial ischemia/reperfusion injury was induced in 8 mice by transient ligation of the LAD coronary artery. Baseline quantitative T1 maps were made at day 1 after surgery, followed by injection of a Gd-based liposomal contrast agent. Five mice served as control group, which followed the same protocol without initial surgery. Twenty-four hours post-injection, a second T1 measurement was performed. Local ΔR1 values were compared with regional wall thickening determined by functional cine CMR and correlated to ex vivo Gd concentrations determined by ICP-MS.ResultsCompared to control values, pre-contrast T1 of infarcted myocardium was slightly elevated, whereas T1 of remote myocardium did not significantly differ. Twenty-four hours post-contrast injection, high ΔR1 values were found in regions with low wall thickening values. However, compared to remote tissue (wall thickening > 45%), ΔR1 was only significantly higher in severe infarcted tissue (wall thickening < 15%). A substantial correlation (r = 0.81) was found between CMR-based ΔR1 values and Gd concentrations from ex vivo ICP-MS measurements. Furthermore, regression analysis revealed that the effective relaxivity of the liposomal contrast agent was only about half the value determined in vitro.Conclusions3D cardiac T1 mapping by CMR can be used to monitor the accumulation of contrast agents in contrast-enhanced studies of murine myocardial infarction. The contrast agent relaxivity was decreased under in vivo conditions compared to in vitro measurements, which needs consideration when quantifying local contrast agent concentrations.

Dataset Information

3D SASHA myocardial T1 mapping with high accuracy and improved precision.

Purpose

Methods

Results

Conclusion

Publications

3D SASHA myocardial T1 mapping with high accuracy and improved precision.

Similar Datasets

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