MRI using radiofrequency magnetic field phase gradients

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Journal titleMagnetic Resonance in Medicine
Pages151161; # of pages: 11
SubjectMRI; radiofrequency; RF phase gradient; low field; TRASE
AbstractConventionally, MR images are formed by applying gradients to the main static magnetic field (B0). However, the B0 gradient equipment is expensive, power-hungry, complex, and noisy and can induce eddy currents in nearby conducting structures, including the patient. Here, we describe a new silent, B0 gradient-free MRI principle, Transmit Array Spatial Encoding (TRASE), based on phase gradients of the radio-frequency (RF) field. RF phase gradients offer a new method of k-space traversal. Echo trains using at least two different RF phase gradients allow spin phase to accumulate, causing k-space traversal. Two such RF fields provide one-dimensional imaging and three are sufficient for two-dimensional imaging. Since TRASE is a k-space method, analogues of many conventional pulse sequences are possible. Experimental results demonstrate one-dimensional and two-dimensional RF MRI and slice selection using a single-channel, transmit/receive, 0.2 T, permanent magnet, human MR system. The experimentally demonstrated spatial resolution is much higher than that provided by RF receive coil array sensitivity encoding alone but lower than generally achievable with B0 gradients. Potential applications are those in which one or more of the features of simplified equipment, lower costs, silent MRI, or the different physics of the image formation process are particularly advantageous
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AffiliationNRC Institute for Biodiagnostics; National Research Council Canada
Peer reviewedYes
NPARC number17541794
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Record identifierdcb1afce-003d-449d-b833-c5ace85ef71e
Record created2011-04-03
Record modified2016-05-09
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