Ungated, plug-and-play preclinical cardiac CEST-MRI using radial FLASH with segmented saturation

Area of Science:

• Biomedical Imaging
• Magnetic Resonance Imaging (MRI)
• Molecular Imaging

Background:

• Preclinical cardiac CEST-MRI is challenging due to T1 variability, RF interference, and cardiac/respiratory motion.
• Traditional gating methods (ECG, respiratory) introduce complexity and potential for error in cardiac MRI.
• Accurate quantification of CEST contrasts (amide, Cr) is crucial for preclinical cardiac studies.

Purpose of the Study:

• To develop and validate an ungated method for preclinical cardiac CEST-MRI in mice.
• To assess the feasibility of simplifying cardiac CEST-MRI acquisition without gating.
• To compare quantitative CEST contrasts obtained with gated and ungated methods.

Main Methods:

• A novel segmented saturation module with radial FLASH readouts and golden angle progression was employed.
• Steady-state saturation was achieved and dominated contrast during gridding and reconstruction.
• Z-spectra were acquired in healthy mice using both gated and ungated methods at various B1 values.

Main Results:

• No significant differences in amide, Cr, or magnetization transfer CEST contrasts were observed between gated and ungated methods.
• An optimal saturation power of 1.8μT was identified for amide and Cr contrast without complicating quantification.
• The ungated radial FLASH acquisition significantly reduced variability in CEST contrast measurements (p < 0.01).

Conclusions:

• The developed ungated method enables reliable CEST mapping in the murine myocardium.
• Quantitative CEST contrasts are consistent with gated sequences, with significantly reduced variance.
• This approach enhances accessibility of preclinical cardiac CEST-MRI for broader research applications.