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Truncated sinc slice excitation for 31P spectroscopic imaging
J R MacFall1, H C Charles, R Prost
1Department of Radiology, Duke University, Durham, North Carolina 27710.
Magnetic Resonance Imaging
|January 1, 1990
Summary
Truncated sinc excitation significantly reduces delay (Td) in 31P magnetic resonance spectroscopy, improving spectral quality. This method offers shorter acquisition times and reduced spectral distortion compared to conventional sinc excitation.
Area of Science:
- Magnetic Resonance Imaging
- Spectroscopy
- Biophysics
Background:
- Shortest possible delay (Td) is crucial for high-quality 31P spectra in multivoxel spectroscopic imaging.
- Conventional sinc excitation can lead to spectral distortion and signal loss due to limitations in radiofrequency (rf) pulse design and gradient switching times.
- Truncated sinc excitation offers a potential solution for achieving shorter Td values.
Purpose of the Study:
- To compare slice profiles, signal-to-noise ratio (SNR), and spectral distortions between conventional sinc and truncated sinc excitation methods.
- To evaluate the performance of these methods at the minimum achievable delay (Td) on a commercial MRI system.
- To assess the impact of truncated sinc excitation on 31P spectroscopic imaging quality.
Main Methods:
- Slice profiles were calculated using Bloch equations and validated with phantom measurements.
- Signal-to-noise ratio (SNR) and spectral distortions were assessed from whole-slice spectra in human volunteers.
- Conventional and truncated sinc rf excitation pulses were compared on a commercial MRI system with 1 G/cm gradients.
Main Results:
- Truncated sinc excitation achieved a shorter Td (1.5 msec) compared to conventional sinc excitation (2.5 msec) for a 2.5-cm slice at 31P frequencies.
- Truncated sinc excitation resulted in significantly smaller spectral distortions.
- While slice profile corrected SNR for the beta-ATP peak was equivalent, truncated sinc showed improved SNR in the phosphodiester (PDE) region.
Conclusions:
- Truncated sinc excitation is a viable method for reducing Td in 31P spectroscopic imaging, leading to improved spectral quality.
- Despite minor dispersive tails in its slice profile, truncated sinc excitation offers advantages in reducing spectral distortion and potentially enhancing SNR in specific spectral regions.
- This technique holds promise for advancing high-quality 31P spectroscopy in clinical and research settings.