Halting the Effects of Flow Enhancement With Effective Intermittent Zeugmatographic Encoding (HEFEWEIZEN) in SSFP

Purpose: To describe a new method for performing dark blood (DB) magnetization preparation in TrueFISP (bSSFP) and apply the technique to high-resolution carotid artery imaging. Materials and Methods: The developed method (HEFE- WEIZEN) provides directional flow suppression, while pre- serving bSSFP contrast, by periodically applying spatial saturation in short repetition time (TR) TrueFISP. Steady- state free precession (SSFP) conditions are maintained throughout the acquisition for the imaging slice magneti- zation. HEFEWEIZEN was implemented on a 1.5 T scanner with standard receiver coils. Studies were performed in phantoms, eight asymptomatic volunteers, and two pa- tients with low- and high-grade carotid artery stenosis. Results: Average flow suppression was 88% 4% (arterial) and 85% 3% (venous) in a multislice study. Stationary signal, contrast, and fine details were maintained with only slight signal suppression (11% 11%). Comparison to dif- fusion-prepared SSFP in the common carotid artery dem- onstrated significant improvement in wall-lumen contrast- to-noise ratio efficiency (P 0.024). DB contrast was achieved with only 13% increased acquisition time (14.3 sec). Further acceleration was possible by confining the DB preparation to the central 60% of k-space. Conclusion: A fast, short TR, DB TrueFISP pulse sequence was developed and tested in the carotid arteries of asymp- tomatic volunteers and patients.