AbdElMonem M. El-Sharkawy1, Di Qian, 1,2,
Paul A. Bottomley1,2, William A. Edelstein1
1Russell H. Morgan Department of
Radiology and Radiological Science, Johns Hopkins University, Baltimore, MD,
United States; 2Electrical and Computer Enginnering, Johns Hopkins
University, Baltimore, MD, United States
Accurate
measurements of RF power deposition are central to safe MRI operation,
especially at higher fields. We have characterized the losses in the body
coil, cables, filter box, transmit-switch and quadrature hybrid. We find that
transmit chain and body coil losses are such that the power reaching the
patient is < 50% of the power supplied by the transmitter. Measured power
deposition in four subjects of different body mass indices varied from 46-83%
of the scanner estimated power deposition. This indicates that scanner
estimates are not accurate indicators of MRI RF exposure.
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