Abstract
Susceptibility induced signal loss is a limitation in gradient echo functional MRI. The through-plane artifact in axial slices is particularly problematic due to the inferior position of air cavities in the brain. Spectral-spatial radiofrequency pulses have recently been shown to reduce signal loss in a single excitation. The pulses were successfully demonstrated assuming a linear relationship between susceptibility gradient and frequency, however, the exact frequency and spatial distribution of the susceptibility gradient in the brain is unknown. We present a spiral spectroscopic imaging sequence with a time-shifted radiofrequency pulse that can spectrally decompose the through-plane susceptibility gradient for spectral-spatial radiofrequency pulse design. Maps of the through-plane susceptibility gradient as a function of frequency were generated for the human brain at 3T. We found that the linear relationship holds well for the whole brain with an optimal slope of -1.0 μT/m/Hz.
Original language | English |
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Pages (from-to) | 1905-1910 |
Number of pages | 6 |
Journal | Magnetic Resonance in Medicine |
Volume | 68 |
Issue number | 6 |
DOIs | |
Publication status | Published - Dec 2012 |
Externally published | Yes |
Keywords
- Algorithms
- Artifacts
- Brain
- Brain Mapping
- Humans
- Image Enhancement
- Image Interpretation, Computer-Assisted
- Magnetic Resonance Imaging
- Radio Waves
- Reproducibility of Results
- Sensitivity and Specificity