Dataset Information

3D myocardial T1 mapping using saturation recovery.

ABSTRACT: To propose a 3D quantitative high-resolution T1 mapping technique, called 3D SASHA (saturation-recovery single-shot acquisition), which combines a saturation recovery pulse with 1D-navigator-based-respiratory motion compensation to acquire the whole volume of the heart in free breathing. The sequence was tested and validated both in a T1 phantom and in healthy subjects.The 3D SASHA method was implemented on a 1.5T scanner. A diaphragmatic navigator was used to allow free-breathing acquisition and the images were acquired with a resolution of 1.4 × 1.4 × 8?mm3 . For assessment of accuracy and precision the sequence was compared with the reference gold-standard inversion-recovery spin echo (IRSE) pulse sequence in a T1 phantom, while for the in vivo studies (10 healthy volunteers) 3D SASHA was compared with the clinically used 2D MOLLI (3-3-5) and 2D SASHA protocols.There was good agreement between the T1 values measured in a T1 phantom with 3D SASHA and the reference IRSE pulse sequences (1111.6?±?31 msec vs. 1123.6?±?8 msec, P?=?0.9947). Mean and standard deviation of the myocardial T1 values in healthy subjects measured with 2D MOLLI, 2D SASHA, and 3D SASHA sequences were 881?±?40 msec, 1181.3?±?32 msec, and 1153.6?±?28 msec respectively.The proposed 3D SASHA sequence allows for high-resolution free-breathing whole-heart T1 -mapping with T1 values in good agreement with the 2D SASHA and improved precision.2 Technical Efficacy: Stage 1 J. MAGN. RESON. IMAGING 2017;46:218-227.

SUBMITTER: Nordio G

PROVIDER: S-EPMC5518207 | biostudies-other | 2017 Jul

REPOSITORIES: biostudies-other

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3D myocardial T<sub>1</sub> mapping using saturation recovery.

Nordio Giovanna G Henningsson Markus M Chiribiri Amedeo A Villa Adriana D M ADM Schneider Torben T Botnar René M RM Botnar René M RM

Journal of magnetic resonance imaging : JMRI 20170202 1

<h4>Purpose</h4>To propose a 3D quantitative high-resolution T<sub>1</sub> mapping technique, called 3D SASHA (saturation-recovery single-shot acquisition), which combines a saturation recovery pulse with 1D-navigator-based-respiratory motion compensation to acquire the whole volume of the heart in free breathing. The sequence was tested and validated both in a T<sub>1</sub> phantom and in healthy subjects.<h4>Materials and methods</h4>The 3D SASHA method was implemented on a 1.5T scanner. A dia ...[more]

PMID: 28152227

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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.

Project description:BackgroundMyocardial T1-mapping recently emerged as a promising quantitative method for non-invasive tissue characterization in numerous cardiomyopathies. Commonly performed with an inversion-recovery (IR) magnetization preparation at 1.5T, the application at 3T has gained due to increased quantification precision. Alternatively, saturation-recovery (SR) T1-mapping has recently been introduced at 1.5T for improved accuracy. Thus, the purpose of this study is to investigate the robustness and precision of SR T1-mapping at 3T and to establish accurate reference values for native T1-times and extracellular volume fraction (ECV) of healthy myocardium.MethodsBalanced Steady-State Free-Precession (bSSFP) Saturation-Pulse Prepared Heart-rate independent Inversion-REcovery (SAPPHIRE) and Saturation-recovery Single-SHot Acquisition (SASHA) T1-mapping were compared with the Modified Look-Locker inversion recovery (MOLLI) sequence at 3T. Accuracy and precision were studied in phantom. Native and post-contrast T1-times and regional ECV were determined in 20 healthy subjects (10 men, 27?±?5 years). Subjective image quality, susceptibility artifact rating, in-vivo precision and reproducibility were analyzed.ResultsSR T1-mapping showed <4 % deviation from the spin-echo reference in phantom in the range of T1?=?100-2300 ms. The average quality and artifact scores of the T1-mapping methods were: MOLLI:3.4/3.6, SAPPHIRE:3.1/3.4, SASHA:2.9/3.2; (1: poor - 4: excellent/1: strong - 4: none). SAPPHIRE and SASHA yielded significantly higher T1-times (SAPPHIRE: 1578?±?42 ms, SASHA: 1523?±?46 ms), in-vivo T1-time variation (SAPPHIRE: 60.1?±?8.7 ms, SASHA: 70.0?±?9.3 ms) and lower ECV-values (SAPPHIRE: 0.20?±?0.02, SASHA: 0.21?±?0.03) compared with MOLLI (T1: 1181?±?47 ms, ECV: 0.26?±?0.03, Precision: 53.7?±?8.1 ms). No significant difference was found in the inter-subject variability of T1-times or ECV-values (T1: p?=?0.90, ECV: p?=?0.78), the observer agreement (inter: p?>?0.19; intra: p?>?0.09) or consistency (inter: p?>?0.07; intra: p?>?0.17) between the three methods.ConclusionsSaturation-recovery T1-mapping at 3T yields higher accuracy, comparable inter-subject, inter- and intra-observer variability and less than 30 % precision-loss compared to MOLLI.

Dataset Information

3D myocardial T1 mapping using saturation recovery.

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3D myocardial T<sub>1</sub> mapping using saturation recovery.

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