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| Main Authors: | , , , , , |
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| Format: | Preprint |
| Published: |
2024
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2410.01501 |
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| _version_ | 1866910628695769088 |
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| author | Šiurytė, Paulina van de Velde, Robert van Leeuwen, Jasper Akgun, Omer Can Brink, Wyger Weingärtner, Sebastian |
| author_facet | Šiurytė, Paulina van de Velde, Robert van Leeuwen, Jasper Akgun, Omer Can Brink, Wyger Weingärtner, Sebastian |
| contents | Inhomogeneity of the transmitted radiofrequency field B1+ is a major factor hindering the image quality in Magnetic Resonance Imaging (MRI) at high field strengths. Here, a novel approach is presented, to locally modulate the B1+ utilizing an array of high permittivity materials with switchable connections. A 3$\times$3 array of barium titanate suspension elements was constructed, with two PIN diode-based switchable connectors per element. Electromagnetic simulations were performed to determine configurations that produce strong B1+ modulation. Remote B1+ field switching was tested in a disk- and and a torso-shaped phantom at 3T by applying different bias voltages to the PIN diodes. The attained B1+ modulation was assessed at various switching pattern positions and various depths within the phantoms. The configuration with the strongest effect size has produced up to 11% modulation in simulations at 15 mm depth, with excellent translation properties. The effects were successfully replicated in phantoms, with a 5 V bias voltage producing up to 11.6$\pm$0.2% modulation. At the relative depth of the human heart, up to 6% of modulation was observed in the torso phantom. The presented method may provide a promising direction for cost-effective, and adaptive B1+ shimming without changes to the scanner hardware. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2410_01501 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Adaptive Radiofrequency Shimming in MRI using Reconfigurable Dielectric Materials Šiurytė, Paulina van de Velde, Robert van Leeuwen, Jasper Akgun, Omer Can Brink, Wyger Weingärtner, Sebastian Medical Physics Applied Physics Inhomogeneity of the transmitted radiofrequency field B1+ is a major factor hindering the image quality in Magnetic Resonance Imaging (MRI) at high field strengths. Here, a novel approach is presented, to locally modulate the B1+ utilizing an array of high permittivity materials with switchable connections. A 3$\times$3 array of barium titanate suspension elements was constructed, with two PIN diode-based switchable connectors per element. Electromagnetic simulations were performed to determine configurations that produce strong B1+ modulation. Remote B1+ field switching was tested in a disk- and and a torso-shaped phantom at 3T by applying different bias voltages to the PIN diodes. The attained B1+ modulation was assessed at various switching pattern positions and various depths within the phantoms. The configuration with the strongest effect size has produced up to 11% modulation in simulations at 15 mm depth, with excellent translation properties. The effects were successfully replicated in phantoms, with a 5 V bias voltage producing up to 11.6$\pm$0.2% modulation. At the relative depth of the human heart, up to 6% of modulation was observed in the torso phantom. The presented method may provide a promising direction for cost-effective, and adaptive B1+ shimming without changes to the scanner hardware. |
| title | Adaptive Radiofrequency Shimming in MRI using Reconfigurable Dielectric Materials |
| topic | Medical Physics Applied Physics |
| url | https://arxiv.org/abs/2410.01501 |