Non-Uniformity Normalization Using 3D Canny Edges and Legendre Polynomial Approximation of the Bias Field: Validation on 7T  T1W Brain Images.  ISMRM 2013. Artem Mikheev, Henry Rusinek, Graham Wiggins.

Ultra High Field MRI: What is in Full Bloom & What is Sprouting? ISMRM SCIENTIFIC WORKSHOP  2013.  Artem Mikheev, Henry Rusinek, Graham Wiggins.

Original (Non-uniformity: WM=28.5%  GM=33.5%)

N3-corrected (field smoothness = 10mm.  Nonuniformity WM=13.5%  GM=19.8%)

BiCal (Nonuniformity: WM=7.1%   GM=13.4%)

All acquisitions were performed on a 7T imager (Magnetom; Siemens, Erlangen, Germany) by using a volume-transmit 24-element receive coil array (Nova Medical, Boston, Mass). A 3D automatic shimming was first performed by adjusting all fist and second order shim currents, then shim performance was verified by using the interface on the imager console. This was followed by either sagittal (n=2) or axial (n=2) 3D MPRAGE sequences acquired on four volunteers (28-54 year old, 3 males). The acquisition parameters were: TR/TE/TI=2.6/2600/1100 msec, FA=6°, 248  SL=0.6 mm, 346 × 323 x 248 matrix, acceleration factor of two.