High-resolution fast spin echo imaging of the human brain at 4.7 T: Implementation and sequence characteristics
Corresponding Author
David L. Thomas
Wellcome Trust High Field MR Research Laboratory, Department of Medical Physics and Bioengineering, University College London, London, UK
Wellcome Trust High Field MR Research Laboratory, Department of Medical Physics and Bioengineering, 12 Queen Square, London WC1N 3AR, UK===Search for more papers by this authorEnrico De Vita
Wellcome Trust High Field MR Research Laboratory, Department of Medical Physics and Bioengineering, University College London, London, UK
Search for more papers by this authorRobert Turner
Wellcome Trust High Field MR Research Laboratory, Department of Medical Physics and Bioengineering, University College London, London, UK
Search for more papers by this authorTarek A. Yousry
Institute of Neurology, Queen Square, London, UK
Search for more papers by this authorRoger J. Ordidge
Wellcome Trust High Field MR Research Laboratory, Department of Medical Physics and Bioengineering, University College London, London, UK
Search for more papers by this authorCorresponding Author
David L. Thomas
Wellcome Trust High Field MR Research Laboratory, Department of Medical Physics and Bioengineering, University College London, London, UK
Wellcome Trust High Field MR Research Laboratory, Department of Medical Physics and Bioengineering, 12 Queen Square, London WC1N 3AR, UK===Search for more papers by this authorEnrico De Vita
Wellcome Trust High Field MR Research Laboratory, Department of Medical Physics and Bioengineering, University College London, London, UK
Search for more papers by this authorRobert Turner
Wellcome Trust High Field MR Research Laboratory, Department of Medical Physics and Bioengineering, University College London, London, UK
Search for more papers by this authorTarek A. Yousry
Institute of Neurology, Queen Square, London, UK
Search for more papers by this authorRoger J. Ordidge
Wellcome Trust High Field MR Research Laboratory, Department of Medical Physics and Bioengineering, University College London, London, UK
Search for more papers by this authorAbstract
In this work, a number of important issues associated with fast spin echo (FSE) imaging of the human brain at 4.7 T are addressed. It is shown that FSE enables the acquisition of images with high resolution and good tissue contrast throughout the brain at high field strength. By employing an echo spacing (ES) of 22 ms, one can use large flip angle refocusing pulses (162°) and a low acquisition bandwidth (50 kHz) to maximize the signal-to-noise ratio (SNR). A new method of phase encode (PE) ordering (called “feathering”) designed to reduce image artifacts is described, and the contributions of RF (B1) inhomogeneity, different echo coherence pathways, and magnetization transfer (MT) to FSE signal intensity and contrast are investigated. B1 inhomogeneity is measured and its effect is shown to be relatively minor for high-field FSE, due to the self-compensating characteristics of the sequence. Thirty-four slice data sets (slice thickness = 2 mm; in-plane resolution = 0.469 mm; acquisition time = 11 min 20 s) from normal volunteers are presented, which allow visualization of brain anatomy in fine detail. This study demonstrates that high-field FSE produces images of the human brain with high spatial resolution, SNR, and tissue contrast, within currently prescribed power deposition guidelines. Magn Reson Med 51:1254–1264, 2004. © 2004 Wiley-Liss, Inc.
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