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High‐order multiband encoding in the heart
Author(s) -
Cunningham Charles H.,
Wright Graham A.,
Wood Michael L.
Publication year - 2002
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.10277
Subject(s) - encoding (memory) , excitation , pulse (music) , sensitivity (control systems) , signal (programming language) , artifact (error) , wafer , materials science , phase (matter) , computer science , hadamard transform , optics , biomedical engineering , acoustics , physics , nuclear magnetic resonance , artificial intelligence , electronic engineering , optoelectronics , medicine , quantum mechanics , detector , programming language , engineering
Spatial encoding with multiband selective excitation (e.g., Hadamard encoding) has been restricted to a small number of slices because the RF pulse becomes unacceptably long when more than about eight slices are encoded. In this work, techniques to shorten multiband RF pulses, and thus allow larger numbers of slices, are investigated. A method for applying the techniques while retaining the capability of adaptive slice thickness is outlined. A tradeoff between slice thickness and pulse duration is shown. Simulations and experiments with the shortened pulses confirmed that motion‐induced excitation profile blurring and phase accrual were reduced. The connection between gradient hardware limitations, slice thickness, and flow sensitivity is shown. Excitation profiles for encoding 32 contiguous slices of 1‐mm thickness were measured experimentally, and the artifact resulting from errors in timing of RF pulse relative to gradient was investigated. A multiband technique for imaging 32 contiguous 2‐mm slices, with adaptive slice thickness, was developed and demonstrated for coronary artery imaging in healthy subjects. With the ability to image high numbers of contiguous slices, using relatively short (1–2 ms) RF pulses, multiband encoding has been advanced further toward practical application. Magn Reson Med 48:689–698, 2002. © 2002 Wiley‐Liss, Inc.