Reduction of Scan Time and Echo Time in 3D Time-of-Flight (TOF) MR Angiography, Using Reverse Elliptical Centric Dual-Echo Acquisition

Abstract

In the conventional single-echo three dimension (3D) time-of-flight (T OF) magnetic resonance angiography (MRA), it always takes long scan time to obtain the good images. In addition, high-resolution MRA with flow compensation requires long echo time (T E). Here, a reverse elliptical centric dual-echo 3D T OF MRA p ulse se quence was developed to reduce the scan time and minimize the effective T E. Dual-echo and reverse elliptical centric acquisition in the phase encoding and slice phase encoding direction were used to reduce the scan time by 61%. Furthermore, the effective echo time (T E) was also minimized from 4.8ms to 4 .1ms. T he developed pulse sequence was tested on clinical MRI systems and the contrast to noise ratio (CNR) was measured to evaluate the results. T he results show that the CNR only decrease by 2.5% with the scan time reduced to 39% when compared with the conventional single-echo 3D T OF. Compared with the conventional dual-echo 3D T OF acquisition, the developed pulse sequence brings advantages in three aspects: (1) reduce scan time by 22%; (2) increase CNR by 10%; (3) reduce the artifacts induced by dual-echo effects. In addition, while keeping the similar scan time as the conventional single-echo 3D T OF acquisition, the results show that reverse elliptical centric dual-echo 3D T OF acquisition increase CNR by 54.3%.