Self‐navigation under non‐steady‐state conditions: Cardiac and respiratory self‐gating of inversion recovery snapshot FLASH acquisitions in mice

Winter, Patrick; Kampf, Thomas; Helluy, Xavier; Gutjahr, Fabian Tobias; Meyer, Cord; Bauer, Wolfgang R.; Jakob, Peter M.; Herold, Volker

doi:10.1002/mrm.26068

Cited by 13 publications

(22 citation statements)

References 28 publications

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“…Variability in T 1 SDs can be caused by respiration motion, which could prevent a perfect overlap between inversion slabs and imaging slices. Another source of T 1 errors might come from motion between the acquisitions of the GRE1 and GRE2 blocks of the same slice, which may be corrected through the deletion of motion‐corrupted projections identified by a self‐gating method . Another solution would be to perform 9‐second apnea, which can easily be implemented on humans.…”

Section: Discussionsupporting

confidence: 89%

2D multislice MP2RAGE sequence for fast T₁ mapping at 7 T: Application to mouse imaging and MR thermometry

Faller

Trotier

Rousseau

et al. 2020

Magnetic Resonance in Med

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Purpose:To develop a 2D radial multislice MP2RAGE sequence for fast and reliable T 1 mapping at 7 T in mice and for MR thermometry. Methods: The 2D-MP2RAGE sequence was performed with the following parameters: TI 1 -TI 2 -MP2RAGE TR = 1000-3000-9000 ms. The multiple dead times within the sequence were used for interleaved multislice acquisition, enabling one to acquire six slices in 9 seconds. The excitation pulse shape, inversion selectivity, and interslice gap were optimized. In vitro comparison with the inversion-recovery sequence was performed. The T 1 variations with temperature were measured on tubes with T 1 ranging from 800 ms to 2000 ms. The sequence was used to acquire T 1 maps continuously during 30 minutes on the brain and abdomen of healthy mice. Results: A three-lobe cardinal sine excitation pulse, combined with an inversion slice thickness and an interslice gap of respectively 150% and 50% of the imaging slice thickness, led to a SD and bias of the T 1 measurements below 1% and 2%, respectively. A linear dependence of T 1 with temperature was measured between 10°C and 60°C. In vivo, less than 1% variation was measured between successive T 1 maps in the mouse brain. In the abdomen, no obvious in-plane motion artifacts were observed but respiratory motion in the slice dimension led to 6% T 1 underestimation. Conclusion: The multislice MP2RAGE sequence could be used for fast wholebody T 1 mapping and MR thermometry. Its reconstruction method would enable onthe-fly reconstruction.

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Section: Discussionsupporting

confidence: 89%

2D multislice MP2RAGE sequence for fast T₁ mapping at 7 T: Application to mouse imaging and MR thermometry

Faller

Trotier

Rousseau

et al. 2020

Magnetic Resonance in Med

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“…By considering typical relaxation times of myocardial tissue ( T 1ρ = 40 ms [ 20 ], T 1 = 1400 ms [ 32 ]) and the sequence timings (TR = 5 ms, t rec = 1500 ms) described above, the signal maximum is reached at a slightly different value. In Fig.…”

Section: Methodsmentioning

confidence: 99%

Fast myocardial T1ρ mapping in mice using k-space weighted image contrast and a Bloch simulation-optimized radial sampling pattern

Gram

Gensler

Winter

et al. 2021

Magn Reson Mater Phy

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Purpose T1ρ dispersion quantification can potentially be used as a cardiac magnetic resonance index for sensitive detection of myocardial fibrosis without the need of contrast agents. However, dispersion quantification is still a major challenge, because T1ρ mapping for different spin lock amplitudes is a very time consuming process. This study aims to develop a fast and accurate T1ρ mapping sequence, which paves the way to cardiac T1ρ dispersion quantification within the limited measurement time of an in vivo study in small animals. Methods A radial spin lock sequence was developed using a Bloch simulation-optimized sampling pattern and a view-sharing method for image reconstruction. For validation, phantom measurements with a conventional sampling pattern and a gold standard sequence were compared to examine T1ρ quantification accuracy. The in vivo validation of T1ρ mapping was performed in N = 10 mice and in a reproduction study in a single animal, in which ten maps were acquired in direct succession. Finally, the feasibility of myocardial dispersion quantification was tested in one animal. Results The Bloch simulation-based sampling shows considerably higher image quality as well as improved T1ρ quantification accuracy (+ 56%) and precision (+ 49%) compared to conventional sampling. Compared to the gold standard sequence, a mean deviation of − 0.46 ± 1.84% was observed. The in vivo measurements proved high reproducibility of myocardial T1ρ mapping. The mean T1ρ in the left ventricle was 39.5 ± 1.2 ms for different animals and the maximum deviation was 2.1% in the successive measurements. The myocardial T1ρ dispersion slope, which was measured for the first time in one animal, could be determined to be 4.76 ± 0.23 ms/kHz. Conclusion This new and fast T1ρ quantification technique enables high-resolution myocardial T1ρ mapping and even dispersion quantification within the limited time of an in vivo study and could, therefore, be a reliable tool for improved tissue characterization.

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“…Compared to humans, where the cardiac cycle has a duration of 600–1000 ms at rest, the cardiac cycle of mice is extremely short, commonly 100–140 ms [ 37 ]. As a result, complete acquisition in one cycle cannot be carried out for a single T 1ρ weighted image.…”

Section: Introductionmentioning

confidence: 99%

Quantification correction for free-breathing myocardial T1ρ mapping in mice using a recursively derived description of a T1ρ* relaxation pathway

Gram

Gensler

Albertova

et al. 2022

Journal of Cardiovascular Magnetic Resonance

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Background Fast and accurate T1ρ mapping in myocardium is still a major challenge, particularly in small animal models. The complex sequence design owing to electrocardiogram and respiratory gating leads to quantification errors in in vivo experiments, due to variations of the T1ρ relaxation pathway. In this study, we present an improved quantification method for T1ρ using a newly derived formalism of a T1ρ* relaxation pathway. Methods The new signal equation was derived by solving a recursion problem for spin-lock prepared fast gradient echo readouts. Based on Bloch simulations, we compared quantification errors using the common monoexponential model and our corrected model. The method was validated in phantom experiments and tested in vivo for myocardial T1ρ mapping in mice. Here, the impact of the breath dependent spin recovery time Trec on the quantification results was examined in detail. Results Simulations indicate that a correction is necessary, since systematically underestimated values are measured under in vivo conditions. In the phantom study, the mean quantification error could be reduced from − 7.4% to − 0.97%. In vivo, a correlation of uncorrected T1ρ with the respiratory cycle was observed. Using the newly derived correction method, this correlation was significantly reduced from r = 0.708 (p < 0.001) to r = 0.204 and the standard deviation of left ventricular T1ρ values in different animals was reduced by at least 39%. Conclusion The suggested quantification formalism enables fast and precise myocardial T1ρ quantification for small animals during free breathing and can improve the comparability of study results. Our new technique offers a reasonable tool for assessing myocardial diseases, since pathologies that cause a change in heart or breathing rates do not lead to systematic misinterpretations. Besides, the derived signal equation can be used for sequence optimization or for subsequent correction of prior study results.

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Self‐navigation under non‐steady‐state conditions: Cardiac and respiratory self‐gating of inversion recovery snapshot FLASH acquisitions in mice

Cited by 13 publications

References 28 publications

2D multislice MP2RAGE sequence for fast T₁ mapping at 7 T: Application to mouse imaging and MR thermometry

2D multislice MP2RAGE sequence for fast T₁ mapping at 7 T: Application to mouse imaging and MR thermometry

Fast myocardial T1ρ mapping in mice using k-space weighted image contrast and a Bloch simulation-optimized radial sampling pattern

Quantification correction for free-breathing myocardial T1ρ mapping in mice using a recursively derived description of a T1ρ* relaxation pathway

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Self‐navigation under non‐steady‐state conditions: Cardiac and respiratory self‐gating of inversion recovery snapshot FLASH acquisitions in mice

Cited by 13 publications

References 28 publications

2D multislice MP2RAGE sequence for fast T1 mapping at 7 T: Application to mouse imaging and MR thermometry

2D multislice MP2RAGE sequence for fast T1 mapping at 7 T: Application to mouse imaging and MR thermometry

Fast myocardial T1ρ mapping in mice using k-space weighted image contrast and a Bloch simulation-optimized radial sampling pattern

Quantification correction for free-breathing myocardial T1ρ mapping in mice using a recursively derived description of a T1ρ* relaxation pathway

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2D multislice MP2RAGE sequence for fast T₁ mapping at 7 T: Application to mouse imaging and MR thermometry

2D multislice MP2RAGE sequence for fast T₁ mapping at 7 T: Application to mouse imaging and MR thermometry