Purpose: 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).
Materials and Methods: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.Results: 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.
Conclusion: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.