dorsal/arxiv
View SchemaParallel MRI at microtesla fields
| Authors | V. S. Zotev, P. L. Volegov, A. N. Matlashov, M. A. Espy, J. C. Mosher, R. H. Kraus Jr |
|---|---|
| Categories | |
| ArXiv ID | physics/0701188 |
| URL | https://arxiv.org/abs/physics/0701188 |
| DOI | 10.1016/j.jmr.2008.02.015 |
| Journal | J.Magn.Resonance192:197,2008 |
Abstract
Parallel imaging techniques have been widely used in high-field magnetic resonance imaging (MRI). Multiple receiver coils have been shown to improve image quality and allow accelerated image acquisition. Magnetic resonance imaging at ultra-low fields (ULF MRI) is a new imaging approach that uses SQUID (superconducting quantum interference device) sensors to measure the spatially encoded precession of pre-polarized nuclear spin populations at microtesla-range measurement fields. In this work, parallel imaging at microtesla fields is systematically studied for the first time. A seven-channel SQUID system, designed for both ULF MRI and magnetoencephalography (MEG), is used to acquire 3D images of a human hand, as well as 2D images of a large water phantom. The imaging is performed at 46 microtesla measurement field with pre-polarization at 40 mT. It is shown how the use of seven channels increases imaging field of view and improves signal-to-noise ratio for the hand images. A simple procedure for approximate correction of concomitant gradient artifacts is described. Noise propagation is analyzed experimentally, and the main source of correlated noise is identified. Accelerated imaging based on one-dimensional undersampling and 1D SENSE (sensitivity encoding) image reconstruction is studied in the case of the 2D phantom. Actual 3-fold imaging acceleration in comparison to single-average fully encoded Fourier imaging is demonstrated. These results show that parallel imaging methods are efficient in ULF MRI, and that imaging performance of SQUID-based instruments improves substantially as the number of channels is increased.
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"abstract": "Parallel imaging techniques have been widely used in high-field magnetic\nresonance imaging (MRI). Multiple receiver coils have been shown to improve\nimage quality and allow accelerated image acquisition. Magnetic resonance\nimaging at ultra-low fields (ULF MRI) is a new imaging approach that uses SQUID\n(superconducting quantum interference device) sensors to measure the spatially\nencoded precession of pre-polarized nuclear spin populations at\nmicrotesla-range measurement fields. In this work, parallel imaging at\nmicrotesla fields is systematically studied for the first time. A seven-channel\nSQUID system, designed for both ULF MRI and magnetoencephalography (MEG), is\nused to acquire 3D images of a human hand, as well as 2D images of a large\nwater phantom. The imaging is performed at 46 microtesla measurement field with\npre-polarization at 40 mT. It is shown how the use of seven channels increases\nimaging field of view and improves signal-to-noise ratio for the hand images. A\nsimple procedure for approximate correction of concomitant gradient artifacts\nis described. Noise propagation is analyzed experimentally, and the main source\nof correlated noise is identified. Accelerated imaging based on one-dimensional\nundersampling and 1D SENSE (sensitivity encoding) image reconstruction is\nstudied in the case of the 2D phantom. Actual 3-fold imaging acceleration in\ncomparison to single-average fully encoded Fourier imaging is demonstrated.\nThese results show that parallel imaging methods are efficient in ULF MRI, and\nthat imaging performance of SQUID-based instruments improves substantially as\nthe number of channels is increased.",
"arxiv_id": "physics/0701188",
"authors": [
"V. S. Zotev",
"P. L. Volegov",
"A. N. Matlashov",
"M. A. Espy",
"J. C. Mosher",
"R. H. Kraus Jr"
],
"categories": [
"physics.med-ph",
"physics.ins-det"
],
"doi": "10.1016/j.jmr.2008.02.015",
"journal_ref": "J.Magn.Resonance192:197,2008",
"title": "Parallel MRI at microtesla fields",
"url": "https://arxiv.org/abs/physics/0701188"
},
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