Comparison between eight- and sixteen-channel TEM transceive arrays for body imaging at 7 T

• Published in: Magnetic resonance in medicine Vol. 67; no. 4; pp. 954 - 964
• Main Authors: Snyder, C. J., DelaBarre, L., Moeller, S., Tian, J., Akgun, C., Van de Moortele, P.-F., Bolan, P. J., Ugurbil, K., Vaughan, J. T., Metzger, G. J.
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 01.04.2012
• Subjects: 7 T body imaging; 7 tesla; Computer Simulation; Equipment Design; Humans; Image Enhancement - methods; Image Interpretation, Computer-Assisted; Magnetic Resonance Imaging - instrumentation; Male; Models, Statistical; Pelvis - anatomy & histology; SAR; TEM coil; transmit/receive arrays; ultra high field
• ISSN: 0740-3194; 1522-2594
• DOI: 10.1002/mrm.23070

Eight‐ and sixteen‐channel transceive stripline/TEM body arrays were compared at 7 T (297 MHz) both in simulation and experiment. Despite previous demonstrations of similar arrays for use in body applications, a quantitative comparison of the two configurations has not been undertaken to date. Results were obtained on a male pelvis for assessing transmit, signal to noise ratio, and parallel imaging performance and to evaluate local power deposition versus transmit B1 (B1+). All measurements and simulations were conducted after performing local B1+ phase shimming in the region of the prostate. Despite the additional challenges of decoupling immediately adjacent coils, the sixteen‐channel array demonstrated improved or nearly equivalent performance to the eight‐channel array based on the evaluation criteria. Experimentally, transmit performance and signal to noise ratio were 22% higher for the sixteen‐channel array while significantly increased reduction factors were achievable in the left–right direction for parallel imaging. Finite difference time domain simulations demonstrated similar results with respect to transmit and parallel imaging performance, however, a higher transmit efficiency advantage of 33% was predicted. Simulations at both 3 and 7 T verified the expected parallel imaging improvements with increasing field strength and showed that, for a specific B1+ shimming strategy used, the sixteen‐channel array exhibited lower local and global specific absorption rate for a given B1+. Magn Reson Med, 2011. © 2011 Wiley Periodicals, Inc.