A physical phantom for amine chemical exchange saturation transfer (CEST) MRI

Area of Science:

• Magnetic Resonance Imaging
• Biomedical Engineering
• Chemical Engineering

Background:

• Chemical Exchange Saturation Transfer (CEST) MRI is a promising technique for molecular imaging.
• Developing stable phantoms is crucial for validating CEST MRI sequences and ensuring reliable results.
• Existing phantoms may lack the necessary stability or versatility for comprehensive testing.

Purpose of the Study:

• To develop a robust amine CEST MRI physical phantom.
• To validate the temporal stability of the phantom's chemical and MRI properties.
• To create supporting software for automated image processing and quality assurance.

Main Methods:

• An acrylic rack with 18 vials containing solutions of varying pH, glycine, and gadolinium concentrations was designed.
• Glycine degradation was assessed via UV absorbance over 70 days.
• pH, relaxation rates (R1, R2), and CEST contrast were measured for 94 days post-preparation.
• Spearman's correlation, linear regression, and Bland-Altman analysis were used for stability validation.

Main Results:

• No significant degradation of glycine was observed over the study period (p > 0.05).
• The phantom demonstrated excellent temporal stability for pH and MRI measurements for up to 3 months.
• High consistency across time points was confirmed with R² values of 1.00 for pH, R1, R2, and CEST contrast.
• Bland-Altman plots further validated the stability and consistency of the measurements.

Conclusions:

• A robust, easily assembled, and transferable amine CEST MRI phantom with 18 distinct solutions was successfully developed.
• The phantom exhibits excellent short-term chemical and MRI stability.
• This phantom is expected to significantly aid in the development of novel CEST MRI sequences and facilitate cross-scanner validation studies.