Time-Resolved TOF MR Angiography in Mice Using a Prospective 3D Radial Double Golden Angle Approach

PurposeTo develop an undersampled anatomical, three-dimensional (3-D) time-resolved magnetic resonance angiography (MRA) method for small animals based on time-of-flight (TOF) effect and radial sampling. MethodsMouse carotid arteries and Circle of Willis images were acquired on a 7T scanner with an electrocardiogram (ECG)-triggered sequence. Preliminary experiments were used to generate an approximately uniform distribution of radial projections with a first golden angle and to produce anatomical TOF images. A second golden angle ratio between consecutive projections of cine acquisitions was added to make it possible to use a temporal filter during reconstruction of time-resolved angiography. A decreasing number of projections were tested, and their impact on signal-to-noise ratio (SNR) and spatial resolution was assessed. ResultsIn anatomical MRA, the undersampled radial approach efficiently allows fast acquisition of mouse angiogram in 3D (22 sec). It was also only slightly sensitive to motion and flow artifacts. The time-resolved sequence can be performed with only 2,500 projections per cine and a temporal resolution under 4 ms in a relatively short acquisition time (less than 5 min). ConclusionThis technique simultaneously provided high 3D isotropic spatial resolution and excellent temporal resolution with a good SNR level, allowing blood flow to be visualized in a restricted acquisition time. Magn Reson Med 73:984-994, 2015. (c) 2014 Wiley Periodicals, Inc.