Combination of optimized transmit arrays and some receive array reconstruction methods can yield homogeneous images at very high frequencies.
Image inhomogeneity related to high radiofrequencies is one of the major challenges for high field imaging. This inhomogeneity can be thought of as having 2 radiofrequency-field related contributors: the transmit field distribution and the reception field distribution. Adjusting magnitude and phase of currents in elements of a transmit array can significantly improve flip angle homogeneity at high field. Effective application of some well-known parallel imaging and other receive array post-processing methods removes receptivity patterns from the intensity distribution in the final image, though noise then becomes a function of position in the final image. Here simulations are used to show that, assuming high signal-to-noise ratio, very homogeneous images in the human head can be acquired with the combination of transmit arrays and some receive array reconstruction methods at frequencies as high as 600 MHz.
Collins
Christopher M
CM
Center for NMR Research, Penn State College of Medicine, Hershey, PA 17033, USA. cmcollins@psu.edu
Liu
Wanzhan
W
Swift
Bryan J
BJ
Smith
Michael B
MB
D000465:Algorithms; D001921:Brain / Q000033:anatomy & histology*; D003198:Computer Simulation; D017076:Computer-Aided Design; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000295:instrumentation / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000295:instrumentation* / Q000379:methods*; D008954:Models, Biological; D019047:Phantoms, Imaging; D011846:Radio Waves; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014159:Transducers