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Abstract #2153

Active Head Coil Detuning: A Method to Reduce SAR in CASL at 7T

Randall B. Stafford1, 2, Se-Hong Oh1, 2, Myung-Kyun Woo3, Tiejun Zhao4, Kyoung-Nam Kim3, Young-Bo Kim3, Zang-Hee Cho3, John A. Detre1, 2, Jongho Lee1, 2

1Radiology, University of Pennsylvania, Philadelphia, PA, United States; 2Center for Functional Neuroimaging, University of Pennsylvania, Philadelphia, PA, United States; 3Neuroscience Research Institute, Gachon University, Incheon, Korea; 4Siemens Healthcare USA, University of Pittsburgh, Pittsburgh, PA, United States

Arterial spin labeling has the dual benefit of increased spin polarity and elongation of the T1 relaxation time of arterial blood at 7T. In order to realize these benefits at 7T, specific absorption rate limits must be mitigated. One way to reduce the SAR deposition is to eliminate the need for RF power during ASL control acquisitions. Here, we use a novel ASL head/labeling coil system with active detuning to eliminate magnetization transfer effects during labeling, thereby allowing us to remove the control RF. This reduces the SAR deposition by almost 50%, and allows for shorter TRs. We demonstrate the utility of this system for CASL in healthy volunteers with a SAR-minimum TR under 7 seconds.