Abstract #3713
Multi Echo GRE for Thermal Imaging
Yuval Zur 1 , Benny Assif 2 , Alex Volovick 2 , and William Grissom 3
1
GE Healthcare, Tirat Carmel, Israel,
2
Insightec
Ltd., Tirat Carmel, Israel,
3
Biomedical
Engineering, Vanderbilt University, Nashville, Tennesee,
United States
The thermometry sequence used for Focused Ultrasound
(MRgFUS) is multi slice gradient echo. Long TE gives
higher temperature accuracy. To lengthen TE and reduce
noise a low receiver bandwidth is used. However, lower
bandwidth increases spatial shifts due to B0
inhomogeneity. For brain applications accuracy is
mandatory so low bandwidth is not allowed. To overcome
this we use a multi echo GRE sequence where N > 1 echoes
are acquired in each TR. For each echo the bandwidth is
high and therefore spatial shifts are low. The
temperature signal to noise ratio (TSNR) is preserved by
combining signals from all the echoes into a unified
temperature image. Compared to the standard GRE
sequence, the new sequence provides similar or higher
TSNR with a 5 8 fold reduction in spatial shifts.
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