Four‐dimensional MR microscopy of the mouse heart using radial acquisition and liposomal gadolinium contrast agent

Abstract

Magnetic resonance microscopy (MRM) has become an important tool for small animal cardiac imaging. In relation to competing technologies (microCT and ultrasound), MR is limited by spatial resolution, temporal resolution, and acquisition time. All three of these limitations have been addressed by developing a four‐dimensional (4D) (3D plus time) radial acquisition (RA) sequence. The signal‐to‐noise ratio (SNR) has been optimized by minimizing the echo time (TE) (300 us). The temporal resolution and throughput have been improved by center‐out trajectories resulting in repetition time (TR) T₁ of the blood to 3 (voxel volume = 2.7 nL) and acquisition time of 16 min; 2) high‐temporal resolution with spatial resolution of 87 × 87 × 352 um³ (voxel volume = 2.7 nL) and temporal resolution at 4.8 ms and acquisition time of 32 minutes; and 3) high‐resolution isotropic imaging at 87 × 87 × 87 um³ (voxel volume = 0.68 nL) and acquisition time of 31 min. The 4D image arrays allow direct measure of cardiac functional parameters dependent on chamber volumes, e.g., ejection fraction (EF), end diastolic volume (EDV), and end systolic volume (ESV). Magn Reson Med 60:111–118, 2008.