Table 2.
CAMH | MPRC | ZHH | |
---|---|---|---|
MRI system | GE MR750 Discovery | Siemens Trio | GE HDx |
Year of Installation | 2010 | 2011 | 2004 |
Head Coil | 8‐channel | 12‐channel | 8‐channel |
Acceleration | Asset=2 | GRAPPA=2 | Asset=2 |
Echo Time (ms) | 88 | 85 | 88 |
Repetition Time (ms) | 8,800 | 8,800 | 17,000 |
Flip Angle (degrees) | 90/180/180 | 90/180 | 90/180/180 |
FOV (mm) | 256 | 256 | 256 |
In‐plane resolution (mm) | 2.0 × 2.0 | 2.0 × 2.0 | 2.0 × 2.0 |
Slice Thickness (mm) | 2.0 | 2.0 | 2.0 |
Number of Slices | 66 | 66 | 66 |
Partial k‐space acceleration techniques, Array Spatial Sensitivity Encoding Technique (Asset), and Generalized Autocalibrating Partially Parallel Acquisitions (GRAPPA) were used on GE and Siemens scanners, respectively, to reduce effective TE and TE by undersampling k‐space along the phase encoding direction. A twice refocused spin‐echo EPI sequence was used on the GE scanners to improve spatial distortions. A refocused monopolar EPI sequence was used on the Siemens scanner to improve SNR.