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Alternating repetition time balanced steady state free precession.
J Leupold1, J Hennig, K Scheffler
1Department of Diagnostic Radiology, Medical Physics, University Hospital Freiburg, Freiburg, Germany. jochen.leupold@freiburg.de
Magnetic Resonance in Medicine
|February 1, 2006
Summary
A new balanced steady-state free precession (SSFP) method uses two repetition times to suppress fat signals. This technique offers rapid, fat-suppressed imaging for phantoms and volunteers.
Area of Science:
- Magnetic Resonance Imaging
- Pulse Sequence Design
Background:
- Balanced steady-state free precession (SSFP) is a widely used MRI technique.
- Fat suppression is crucial for many MRI applications, but conventional methods can be time-consuming or introduce artifacts.
Purpose of the Study:
- To develop a novel balanced SSFP technique for efficient fat suppression.
- To manipulate the frequency response of balanced SSFP to achieve selective signal suppression.
Main Methods:
- The proposed method employs two alternating repetition times, TR(1) and TR(2), with TR(2) being one-third of TR(1).
- An RF pulse phase increment of 90 degrees is applied.
- The TR(2) is kept short (approx. 1 ms) to alter frequency sensitivity without gradient switching.
- TR(1) is varied (approx. 2.5-4.5 ms) while TR(2) and phase cycling remain constant.
Main Results:
- The technique successfully suppresses off-resonance frequencies, such as fat signals.
- On-resonance spins exhibit magnetization behavior similar to conventional balanced SSFP, with optimal flip angles shifted slightly lower.
- The total scan time increases by approximately 30% compared to standard balanced SSFP.
- Rapid, fat-suppressed images were acquired in phantoms and volunteers.
Conclusions:
- The novel balanced SSFP technique provides effective fat suppression.
- This method offers a viable alternative for rapid, fat-suppressed imaging in MRI.
- The technique demonstrates potential for clinical applications requiring efficient fat suppression.