Three-dimensional isotropic contrast-enhanced MR angiography of the carotid artery using sensitivity-encoding and random elliptic centric k-space filling: technique optimization

We present a study that helped optimize a three-dimensional isotropic contrast-enhanced MR angiographic (CE-MRA) technique, using sensitivity encoding (SENSE) and random elliptic centric k-space filling. Two-dimensional gradient-echo sequence (TR/TE/flip angle 3.4/0.97/40 ) was used to generate time-intensity curves in porcine carotid arteries for a fixed dose of Gd-DTPA (0.02 mmol/kg) at the following intravenous injection rates: 0.1, 0.3, 0.5, 1.0, 1.5, 2.0, and 3.0 ml/s. The time of contrast arrival and time to peak were recorded. Based on the time-intensity curves, three-dimensional high-resolution isotropic (1 mm3) CE-MRA sequence (TR/TE/flip angle: 4.9/2.4/30 ), using SENSE (reduction factor of 2) and random elliptic centric k-space filling, was initiated twice for each of the above injection rates: first at the time of contrast arrival and second at the time of peak contrast. The three-dimensional CE-MRA images were analyzed for artifacts, signal-to-noise ratio, and venous contamination. For the three-dimensional CE-MRA acquisitions that were initiated at the time of contrast arrival, there was a gradual improvement in signal-to-noise ratio (SNR) in the carotid arteries with increasing injection rate. The same trend was not observed for the acquisitions that were initiated at the time of peak contrast. SENSE combined with random elliptic k-space acquisition in CE-MRA allows for higher SNR with fewer ringing artifacts at faster contrast injection rates. (orig.)