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 (TOF) 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 (TE). Here, a reverse elliptical centric dual-echo 3D TOF MRA pulse sequence was developed to reduce the scan time and minimize the effective TE. 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 (TE) was also minimized from 4.8ms to 4.1ms. The developed pulse sequence was tested on clinical MRI systems and the contrast to noise ratio (CNR) was measured to evaluate the results. The 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 TOF. Compared with the conventional dual-echo 3D TOF 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 TOF acquisition, the results show that reverse elliptical centric dual-echo 3D TOF acquisition increase CNR by 54.3%.