Lincoln Craven-Brightman1, Yulin Chang2, Thomas Witzel3, Nicolas S. Arango4, Meher R. Juttukonda1,5, Luis Hernandez-Garcia6, Marta Vidorreta7, John A. Detre8,9, Lawrence L. Wald5,10, and Jason Stockmann5,10
1Massachusetts General Hospital, Charlestown, MA, United States, 2Siemens Medical Solutions USA, Inc., Malvern, PA, United States, 3Qbio Inc, San Carlos, CA, United States, 4Dept. of Electrical Engineering, Massachusetts Institute of Technology, Cambridge, MA, United States, 5Harvard Medical School, Boston, MA, United States, 6Biomedical Engineering, University of Michigan, Ann Arbor, MI, United States, 7Siemens, S.A., Madrid, Spain, 8Neurology, University of Pennsylvania, Philadelphia, PA, United States, 9Radiology, University of Pennsylvania, Philadelphia, PA, United States, 10A.A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA, United States
1Massachusetts General Hospital, Charlestown, MA, United States, 2Siemens Medical Solutions USA, Inc., Malvern, PA, United States, 3Qbio Inc, San Carlos, CA, United States, 4Dept. of Electrical Engineering, Massachusetts Institute of Technology, Cambridge, MA, United States, 5Harvard Medical School, Boston, MA, United States, 6Biomedical Engineering, University of Michigan, Ann Arbor, MI, United States, 7Siemens, S.A., Madrid, Spain, 8Neurology, University of Pennsylvania, Philadelphia, PA, United States, 9Radiology, University of Pennsylvania, Philadelphia, PA, United States, 10A.A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA, United States
We apply local B0 field control with a multi-coil (MC) shim array to improve ASL labeling. Labeling efficiency can be regulated by dynamically shimming the labeling plane. We demonstrate this capability through territory mapping by shifting target arteries out of the labeling pulse bandwidth.
Figure 3.
Experimental territory mapping using B0 local field control to
selectively label internal carotid (IC) arteries. (a) The 1-cm labeling plane is shown with the baseline B0 field maps and voxel freq. histogram inside vertebral and IC artery masks. (b) Shimmed B0 maps and histograms
showing spectral separation of the “desired” left IC from the
“reject”. (c) Similar for right IC. Mean perfusion maps (difference between
labeled and control case) at right show the applied shim field
successfully shifts most of the “reject” arterial spins outside the passband of
the labeling pulse.
Figure 1. Loop geometry and photo/rendering of experimental and simulated B0 shim array hardware considered for ASL applications. B0 field map coverage for each array is shown at left. Representative element field maps are shown for both designs at level of slice shown, in the ASL labeling region. (a) 32-ch “AC/DC” shim array used for proof-of-concept territory mapping experiments. (b) Simulated 12-ch shim array specialized for ASL shimming applications, now under development.