Work

Array‐optimized composite pulse for excellent whole‐brain homogeneity in high‐field MRI

Year: 2007

Type: article

Abstract: A number of methods to improve excitation homogeneity in high-field MRI have been proposed, and some of these methods rely on separate control of radiofrequency (RF) coils in a transmit array. In this work we combine accurate RF field calculations and the Bloch equation to demonstrate that by using a sequence of pulses with individually optimized current distributions (i.e., an array-optimized composite pulse), one can achieve remarkably homogeneous distributions of available signal intensity over the entire brain volume. This homogeneity is greater than that achievable using the same transmit array to produce either a single optimized (or RF shimmed) pulse or a single RF shimmed field distribution in a standard 90x-90y composite pulse arrangement. Simulations indicate that with a very simple array-optimized composite pulse, excellent whole-brain excitation homogeneity can be achieved at up to 600 MHz.

Source: Magnetic Resonance in Medicine

DOI: 10.1002/mrm.21172

Authors: Christopher M. Collins, Zhangwei Wang, Weihua Mao, Jieming Fang, Wanzhan Liu, Michael B. Smith

Institutions: Pennsylvania State University, University of Minnesota

Language: English

Topic: Advanced MRI Techniques and Applications

Subfield: Radiology, Nuclear Medicine and Imaging

Field: Medicine

Domain: Health Sciences

Open Access status: green

Funders: National Institutes of Health, National Institute of Biomedical Imaging and Bioengineering, National Center for Research Resources