Visualization of external carotid artery and its branches: Non–contrast‐enhanced MR angiography using balanced steady‐state free‐precession sequence and a time‐spatial labeling inversion pulse

Abstract

To evaluate visibility of the external carotid artery (ECA) and its branches using three-dimensional (3D) balanced steady-state free-precession (SSFP) MR angiography with a time-spatial labeling inversion pulse (Time-SLIP), and to provide an optimal value of the inversion time (TI). Peripheral-pulse-wave-gated 3D balanced SSFP images were obtained in 20 healthy volunteers. Images with a Time-SLIP using four different TIs (600, 900, 1200, and 1500 ms) and without a Time-SLIP, referred to as sequence A to E, were acquired for each subject and compared for visibility scores of ECA system and relative signal intensity (SI) of ECA. Average Friedman rank for overall visibility was 1.63, 3.01, 3.59, 3.58, and 3.20 for sequence A to E, respectively. Sequence C and D yielded significantly higher visibility than sequence A, B, and E. The mean relative SI value was 0.97, 0.87, 0.81, 0.76, and 0.67 for sequence A to E, respectively. Balanced SSFP MR angiography with a Time-SLIP is superior to that without a Time-SLIP, showing excellent visualization of ECA system in approximately 3 min in average with sufficient background suppression including veins and salivary ducts. A TI of 1200 ms was considered to be optimal for this purpose.