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Unbalanced SSFP for super‐resolution in MRI
- Source :
- Magnetic Resonance in Medicine. 85:2477-2489
- Publication Year :
- 2020
- Publisher :
- Wiley, 2020.
-
Abstract
- Purpose To achieve rapid, low specific absorption rate (SAR) super-resolution imaging by exploiting the characteristic magnetization off-resonance profile in SSFP. Theory and methods In the presented technique, low flip angle unbalanced SSFP imaging is used to acquire a series of images at a low nominal resolution that are then combined in a super-resolution strategy analogous to non-linear structured illumination microscopy. This is demonstrated in principle via Bloch simulations and synthetic phantoms, and the performance is quantified in terms of point-spread function (PSF) and SNR for gray and white matter from field strengths of 0.35T to 9.4T. A k-space reconstruction approach is proposed to account for B0 effects. This was applied to reconstruct super-resolution images from a test object at 9.4T. Results Artifact-free super-resolution images were produced after incorporating sufficient preparation time for the magnetization to approach the steady state. High-resolution images of a test object were obtained at 9.4T, in the presence of considerable B0 inhomogeneity. For gray matter, the highest achievable resolution ranges from 3% of the acquired voxel dimension at 0.35T, to 9% at 9.4T. For white matter, this corresponds to 3% and 10%, respectively. Compared to an equivalent segmented gradient echo acquisition at the optimal flip angle, with a fixed TR of 8 ms, gray matter has up to 34% of the SNR at 9.4T while using a ×10 smaller flip angle. For white matter, this corresponds to 29% with a ×11 smaller flip angle. Conclusion This approach achieves high degrees of super-resolution enhancement with minimal RF power requirements.
- Subjects :
- super‐
structured illumination microscopy
SSFP
computer.software_genre
030218 nuclear medicine & medical imaging
White matter
03 medical and health sciences
Magnetization
0302 clinical medicine
Optics
0903 Biomedical Engineering
Flip angle
Voxel
Image Processing, Computer-Assisted
medicine
Radiology, Nuclear Medicine and imaging
High Resolution Imaging
Physics
Science & Technology
Super-Resolution
medicine.diagnostic_test
Phantoms, Imaging
business.industry
Radiology, Nuclear Medicine & Medical Imaging
RF power amplifier
resolution
Specific absorption rate
spatial encoding
Magnetic resonance imaging
Steady-state free precession imaging
Magnetic Resonance Imaging
Nuclear Medicine & Medical Imaging
medicine.anatomical_structure
Artifacts
business
Life Sciences & Biomedicine
computer
030217 neurology & neurosurgery
Subjects
Details
- ISSN :
- 15222594 and 07403194
- Volume :
- 85
- Database :
- OpenAIRE
- Journal :
- Magnetic Resonance in Medicine
- Accession number :
- edsair.doi.dedup.....f4d800cf517747ea3636280e92725f55