BURST Imaging at High Field
BURST is a fast single-shot imaging technique used in magnetic resonance imaging. Most previous implementations of BURST on whole body systems have been carried out at fields of 1.5T and lower. In this work BURST has been implemented on a 3T whole body system. The signal and attenuation character...
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| Format: | Thesis (University of Nottingham only) |
| Language: | English |
| Published: |
2004
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| Online Access: | https://eprints.nottingham.ac.uk/10093/ |
| _version_ | 1848791021268238336 |
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| author | Wilton, Benjamin |
| author_facet | Wilton, Benjamin |
| author_sort | Wilton, Benjamin |
| building | Nottingham Research Data Repository |
| collection | Online Access |
| description | BURST is a fast single-shot imaging technique used in magnetic resonance imaging. Most previous implementations of BURST on whole body systems have been carried out at fields of 1.5T and lower. In this work BURST has been implemented on a 3T whole body system. The signal and attenuation characteristics are discussed, leading to an approximate expression for the optimum echo time.
A novel method for controlling the pulse amplitude envelope is described. It is shown that this can lead to a modest gain in signal with little loss of resolution, or to a much greater gain in signal with more severe blurring of the image.
Frequency modulated RF pulses have been introduced in order to reduce the peak RF power required, which was found to be beyond the range of a 2kW amplifier. The resulting images show a quadratic phase roll in the readout direction, with no reduction in magnitude or image artefacts. A reduction in peak power of more than ten-fold is demonstrated. The maximum reduction factor possible is shown to be approximately equal to the number of pulses applied in the RF train.
The total RF power has been reduced by superimposing a sinusoidal oscillation onto the constant excitation gradient. Each pulse is applied at a gradient minimum, and hence need be of lower bandwidth, while the overall excitation is unchanged. The RF pulses are transformed using VERSE. A reduction in SAR of 32% is demonstrated. Greater reductions can be achieved by increasing the amplitude of the oscillation. However, this technique introduces a moderate amount of acoustic noise into the sequence. |
| first_indexed | 2025-11-14T18:21:53Z |
| format | Thesis (University of Nottingham only) |
| id | nottingham-10093 |
| institution | University of Nottingham Malaysia Campus |
| institution_category | Local University |
| language | English |
| last_indexed | 2025-11-14T18:21:53Z |
| publishDate | 2004 |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | nottingham-100932025-02-28T11:07:08Z https://eprints.nottingham.ac.uk/10093/ BURST Imaging at High Field Wilton, Benjamin BURST is a fast single-shot imaging technique used in magnetic resonance imaging. Most previous implementations of BURST on whole body systems have been carried out at fields of 1.5T and lower. In this work BURST has been implemented on a 3T whole body system. The signal and attenuation characteristics are discussed, leading to an approximate expression for the optimum echo time. A novel method for controlling the pulse amplitude envelope is described. It is shown that this can lead to a modest gain in signal with little loss of resolution, or to a much greater gain in signal with more severe blurring of the image. Frequency modulated RF pulses have been introduced in order to reduce the peak RF power required, which was found to be beyond the range of a 2kW amplifier. The resulting images show a quadratic phase roll in the readout direction, with no reduction in magnitude or image artefacts. A reduction in peak power of more than ten-fold is demonstrated. The maximum reduction factor possible is shown to be approximately equal to the number of pulses applied in the RF train. The total RF power has been reduced by superimposing a sinusoidal oscillation onto the constant excitation gradient. Each pulse is applied at a gradient minimum, and hence need be of lower bandwidth, while the overall excitation is unchanged. The RF pulses are transformed using VERSE. A reduction in SAR of 32% is demonstrated. Greater reductions can be achieved by increasing the amplitude of the oscillation. However, this technique introduces a moderate amount of acoustic noise into the sequence. 2004 Thesis (University of Nottingham only) NonPeerReviewed application/pdf en arr https://eprints.nottingham.ac.uk/10093/1/BURST_Imaging_at_High_Field.pdf Wilton, Benjamin (2004) BURST Imaging at High Field. PhD thesis, University of Nottingham. MRI Magnetic Resonance Imaging RF power RF High Field SAR Specific Absorption Rate VERSE Chirp Chirp pulse |
| spellingShingle | MRI Magnetic Resonance Imaging RF power RF High Field SAR Specific Absorption Rate VERSE Chirp Chirp pulse Wilton, Benjamin BURST Imaging at High Field |
| title | BURST Imaging at High Field |
| title_full | BURST Imaging at High Field |
| title_fullStr | BURST Imaging at High Field |
| title_full_unstemmed | BURST Imaging at High Field |
| title_short | BURST Imaging at High Field |
| title_sort | burst imaging at high field |
| topic | MRI Magnetic Resonance Imaging RF power RF High Field SAR Specific Absorption Rate VERSE Chirp Chirp pulse |
| url | https://eprints.nottingham.ac.uk/10093/ |