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Accuracy and precision of myocardial T1mapping with MOLLI and ShMOLLI at 1.5T and 3.0T: a phantom study
© Falque et al.; licensee BioMed Central Ltd. 2014
Published: 16 January 2014
Previous studies have demonstrated that an increase in extracellular volume measured on MRI is directly proportionate to myocardial fibrosis. Myocardial extracellular volume is proportionate to partition coefficient (λ) and extracellular volume = λ × (1-hematocrit). λ can be measured by assessing the T1 relaxation time before and after injection of contrast medium. The goal of this study is to assess the accuracy and precision of several T1 mapping sequences using a phantom at 1.5 and 3.0T.
Experiments were performed on two magnets; a 1.5T magnet (Avanto, Siemens) and on a 3.0T magnet (Verio, Siemens) with a 32 phased array cardiovascular coil. phantoms were built using 15 separate tubes to produce similar T1 and T2 values of myocardium and blood before and after gadolinium administration. All sequences were tested with an ECG simulation at heart rates 40, 60, 90, 120. To assess the standard T1 value for each tube, we used a tubo spin echo inversion-recovery sequence (TR/TE = 13000/18 ms, with 17 inversion times between 30-9000 ms turbo factor = 7). The T1 value was assessed using an ECG gated single shot modified Look Locker inversion recovery (MOLLI) and several different schemes of Short MOLLI: at 1.5T (α:35°, 5-2 and 4-3-2 sampling schemes; with a pause of 3 HB) and at 3.0T (α:35° and 20°; 5-2 and 4-3-2 sampling schemes; pause: 3 and 4 HB). We calculated errors in the MOLLI T1 estimation according to Error T1 (%) = ((T1MOLLI-T1reference)/T1reference)x100. We assessed the effect of T2 value, T1 value, heart rate and MOLLI schemes on T1 errors.
ShMOLLI sequences provide an accurate assessment of T1 at 1.5T and 3.0T.
This study was supported by the PHRC 2011-A00887-34.
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