K-T Points Design Choices

Scan Parameters

• Phantom @7T, sagittal• 2D 64x64 B-S B1 map• 5mm slice resolution• Ran many iterations of kzfast3d_1ch.m to

explore the design space and its predicted output B1

• B0 inhomogeneity is ignored

Design Requirements

• Choose parameters that has best uniformity given these constraints:– TR < 5ms– Max FA >= 60 deg.– SAR, need to figure out how to relate computed

RF power to this

Partial Dependence on # Subpulses and RF Power Penalty

Questions

• What is the criterion used for uniformity?• Given a # of subpulses and their width, should

the error criterion be monotonically increasing with greater RF penalty?– Will always be achieving less uniformity, so 1st

term is always increasing, can weighted RF power term be any smaller with a change in penalty?

Partial Dependence on Subpulse Width and RF Power Penalty

Partial Dependence on # Subpulses and Subpulse Width

# Subpulses vs. RF Power Penalty with Subpulse Width changing in time

Conclusions

• 12-18 subpulses• 1-7 RF penalty• 0.12-0.2 ms subpulse width, but depends on

B0