Manojkumar Saranathan1, Michael Zeineh2, Geoffrey A. Kerchner3, Mohammad Mehdi Khalighi4, Marcus T. Alley2, Brian K. Rutt2
1Radiology, Stanford University, Stanford, CA , United States; 2Radiology, Stanford University, Stanford, CA, United States; 3Neurology and Neurological Sciences , Stanford University, Stanford, CA, United States; 4Global Applied Science Labatory, GE Healthcare, Menlo Park, CA, United States
Fast Spin Echo (FSE) imaging is increasingly used for fast T2 weighted imaging applications. However, at 7T, the sequence is heavily limited by SAR considerations, severely reducing its time efficiency. Flip angle modulation schemes like SPACE and XETA [1-2], have been proposed for 3D FSE that enable the use of longer echo-train-lengths and help lower SAR due to reduced refocusing flip angles. We optimized the 3D XETA refocusing flip angle train for T2 weighted brain imaging at 7T based on SAR, signal intensity, contrast and point spread function (PSF) considerations, using T1 and T2 values of white/grey matter at 7T. Additionally, we explored the use of composite excitation pulses to mitigate signal loss from B1 inhomogeneity effects. Whole brain 3D T2 imaging was performed on patients using these modifications.
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