7T vs. 4T: RF power, homogeneity, and signal‐to‐noise comparison in head images

TLDR

Experimental results were consistent with calculations using a human head model and Maxwell's equations. SNR, RF field (B1), and RF power requirements for human head imaging were examined at 7 T and 4 T. At 7 T, B1 variation is nearly twice that at 4 T, the 90° pulse power is about double, and brain‑averaged SNR is at least 1.6 times higher. Published in Magn Reson Med 46:24–30 (2001); © 2001 Wiley‑Liss, Inc.

Abstract

Abstract Signal‐to‐noise ratio (SNR), RF field ( B 1 ), and RF power requirement for human head imaging were examined at 7T and 4T magnetic field strengths. The variation in B 1 magnitude was nearly twofold higher at 7T than at 4T (∼42% compared to ∼23%). The power required for a 90° pulse in the center of the head at 7T was approximately twice that at 4T. The SNR averaged over the brain was at least 1.6 times higher at 7T compared to 4T. These experimental results were consistent with calculations performed using a human head model and Maxwell's equations. Magn Reson Med 46:24–30, 2001. © 2001 Wiley‐Liss, Inc.