Zhi Hua Ren1, Jason P. Stockmann2,3, Andrew Dewdney4, and Ray F. Lee1
1Zuckerman Institute, Columbia University, New York, NY, United States, 2Harvard Medical School, Boston, MA, United States, 3Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, MA, United States, 4Siemens Healthcare GmbH, Erlangen, Germany
1Zuckerman Institute, Columbia University, New York, NY, United States, 2Harvard Medical School, Boston, MA, United States, 3Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, MA, United States, 4Siemens Healthcare GmbH, Erlangen, Germany
The spherical harmonic based shimming routine is nonoptimal for the bilateral regions of intersest that are far off isocenter. To address this, a hybrid active and passive local shimming (HAPLS) technique is proposed to shim two isolated areas in one field of view (FOV) simultaneously.
Fig. 3 The photo of the experimental setup
Fig.1 The illustration of the proposed HAPLS approach. The grey cylinder depicts the 60-cm MRI scanner bore, and two 200-mm FoVs with 283 mm apart along the x-axis are surrounded by a total of 8 rows of passive shimming chips and a total of 58 channels of active shimming coils. The dimensions and locations of all chips and current amplitudes in all active shim coils are optimized to improve the field homogeneity in two targeted FOVs.
