Improved solvent suppression and increased spatial excitation bandwidths for three-dimensional PRESS CSI using...

Area of Science:

• Magnetic Resonance Imaging
• Spectroscopy
• Biomedical Engineering

Background:

• Proton (1H) chemical shift imaging (CSI) using the Point Resolved Spectroscopy (PRESS) sequence is crucial for metabolite quantification.
• Water and lipid suppression are critical for accurate PRESS-based CSI, but conventional methods can be limited.
• Dependence of the PRESS box location on chemical shift can affect spectral quality.

Purpose of the Study:

• To develop and evaluate novel dual phase-compensating spectral/spatial echo-planar spin-echo (EPSE) pulses for the PRESS sequence.
• To improve water and lipid suppression in 1H CSI.
• To reduce the dependency of the PRESS box location on chemical shift.

Main Methods:

• Incorporation of asymmetric EPSE pulses into the PRESS excitation sequence.
• Design and testing of three distinct EPSE pulses at 1.5 T for specific applications (brain, general, prostate CSI).
• Evaluation of pulse performance using phantom and in vivo experiments, assessing suppression factors and spatial bandwidth.

Main Results:

• EPSE pulses achieved zero phase spectra, improving spectral quality.
• Suppression factors exceeding 10^4 were obtained for water and lipids with EPSE pulses 1 and 2.
• Increased spatial bandwidths (3.3–5.0 kHz) reduced signal contamination and improved metabolite intensity uniformity within the PRESS box.

Conclusions:

• Dual phase-compensating EPSE pulses significantly enhance water and lipid suppression in PRESS CSI.
• These novel pulses improve spectral/spatial imaging accuracy and metabolite quantification.
• The developed EPSE pulses offer superior performance compared to conventional one-dimensional spin-echo pulses.