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. Author manuscript; available in PMC: 2014 Jun 16.
Published in final edited form as: Phys Med Biol. 2011 Apr 20;56(10):3091–3106. doi: 10.1088/0031-9155/56/10/013

Table 3.

Measurement of the MRI magnet main magnetic field B0 homogeneity in the FOV after the standard MRI shimming procedure before and after the PET gantry was installed in the PET–MR suite. B0 homogeneity was calculated on the characterization volumes based on spherical harmonic representation of the data, as determined from 24-plane, 24-angle measurements on a larger volume.

Volume dimensions
(X/Y/Z, each in cm)		 Standalone MRI
(Vrms, ppm)		 After PET installation
(Vrms, ppm)		 MRI specification
(Vrms, ppm)
40 × 40 × 40 0.37 0.32 <0.5
30 × 30 × 30 0.07 0.08 <0.12
20 × 20 × 20 0.014 0.017 <0.03
10 × 10 ×10 0.002 0.002 <0.004