Whole-cerebrum guanidino and amide CEST mapping at 3 T by a 3D stack-of-spirals gradient echo acquisition

Area of Science:

• Biomedical Engineering
• Neuroimaging
• Magnetic Resonance Imaging

Background:

• Chemical Exchange Saturation Transfer (CEST) MRI is a valuable technique for assessing tissue biochemistry.
• Conventional CEST imaging methods often face limitations in speed, sensitivity, and robustness to motion.

Purpose of the Study:

• To develop and evaluate a novel 3D, high-sensitivity CEST mapping technique using a 3D stack-of-spirals (SOS) gradient echo readout.
• To compare the proposed 3DSOS method against conventional acquisition techniques for concurrent guanidino (Guan) and amide CEST mapping in the human brain at 3T.

Main Methods:

• The 3D stack-of-spirals (SOS) technique was optimized for saturation time and recovery delay for maximal CEST time efficiency.
• The 3DSOS method was compared with segmented 3D EPI (3DEPI), turbo spin echo, and GRASE techniques.
• Image quality, temporal signal-to-noise ratio (tSNR), and test-retest reliability were assessed. Polynomial Lorentzian line-shape fitting (PLOF) was used for analysis.

Main Results:

• Optimized parameters were 1.4s recovery delay and 2s saturation time for both Guan and amide CEST.
• The 3DSOS technique demonstrated comparable GuanCEST signal to 3DEPI in gray and white matter.
• Significantly higher amideCEST signal was achieved with 3DSOS in both gray and white matter compared to 3DEPI.
• 3DSOS exhibited superior scan-rescan reliability and motion robustness over 3DEPI.

Conclusions:

• The developed 3D stack-of-spirals (SOS) CEST technique shows significant promise for whole-cerebrum imaging.
• This novel approach offers uniform contrast and enhanced robustness against motion artifacts.
• The 3DSOS method provides a valuable advancement for quantitative CEST MRI.