Abstract
BackgroundTo overcome flow and electrocardiogram-trigger artifacts in cardiovascular magnetic resonance (CMR), we have implemented a cardiac and respiratory self-gated cine ultra-short echo time (UTE) sequence. We have assessed its performance in healthy mice by comparing the results with those obtained with a self-gated cine fast low angle shot (FLASH) sequence and with echocardiography.Methods2D self-gated cine UTE (TE/TR = 314 μs/6.2 ms, resolution: 129 × 129 μm, scan time per slice: 5 min 5 sec) and self-gated cine FLASH (TE/TR = 3 ms/6.2 ms, resolution: 129 × 129 μm, scan time per slice: 4 min 49 sec) images were acquired at 9.4 T. Volume of the left and right ventricular (LV, RV) myocardium as well as the end-diastolic and -systolic volume was segmented manually in MR images and myocardial mass, stroke volume (SV), ejection fraction (EF) and cardiac output (CO) were determined. Statistical differences were analyzed by using Student t test and Bland-Altman analyses.ResultsSelf-gated cine UTE provided high quality images with high contrast-to-noise ratio (CNR) also for the RV myocardium (CNRblood-myocardium = 25.5 ± 7.8). Compared to cine FLASH, susceptibility, motion, and flow artifacts were considerably reduced due to the short TE of 314 μs. The aortic valve was clearly discernible over the entire cardiac cycle. Myocardial mass, SV, EF and CO determined by self-gated UTE were identical to the values measured with self-gated FLASH and showed good agreement to the results obtained by echocardiography.ConclusionsSelf-gated UTE allows for robust measurement of cardiac parameters of diagnostic interest. Image quality is superior to self-gated FLASH, rendering the method a powerful alternative for the assessment of cardiac function at high magnetic fields.
Highlights
To overcome flow and electrocardiogram-trigger artifacts in cardiovascular magnetic resonance (CMR), we have implemented a cardiac and respiratory self-gated cine ultra-short echo time (UTE) sequence
Image quality Image contrast Stacks of high resolution short-axis cardiac images covering the entire mouse heart were acquired from six healthy mice using the 2D cardiac-respiratory self-gated cine UTE sequence
Image quality was assessed with respect to contrast-to-noise ratio (CNR), and was compared with the results obtained with a conventional cartesian gradient echo (FLASH) sequence that is routinely used in CMR on mouse models
Summary
To overcome flow and electrocardiogram-trigger artifacts in cardiovascular magnetic resonance (CMR), we have implemented a cardiac and respiratory self-gated cine ultra-short echo time (UTE) sequence. Cardiovascular magnetic resonance (CMR) is increasingly often performed at very high magnetic field strength, up to 7 T for human subjects and up to 17.6 T for small animal models [1,2,3,4,5,6,7]. While higher magnetic fields hold the promise of providing better signal-to-noise ratio (SNR), higher spatial resolution or better dynamics, several additional scans to record reference data and do not increase scan time. These techniques, do not mitigate the second crucial issue, flow artifacts. Susceptibility artifacts often impede quantification of right ventricular (RV) mass, which is already difficult due to lower contrast to other tissues at high magnetic fields
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