Double-Step R1rho-Based Lorentzian Fitting (DROF): A New CEST Analysis Approach and Its Comparison With Existing...

Area of Science:

• Magnetic Resonance Imaging
• Biomedical Engineering

Background:

• Chemical Exchange Saturation Transfer (CEST) MRI quantification at 3 Tesla is limited by peak overlap and background signal.
• Existing four-pool Lorentzian fitting methods simplify CEST analysis by treating multiple contrasts as a single pool.
• Fitting accuracy in current methods is sensitive to initial values and boundary conditions.

Purpose of the Study:

• To develop and evaluate a novel CEST analysis method, double-step R1rho-based Lorentzian fitting (DROF), for improved five-pool parameter extraction at 3 Tesla.
• To introduce a comprehensive evaluation framework with three metrics for assessing CEST analysis performance.
• To compare the accuracy and robustness of DROF against existing methods.

Main Methods:

• Development of DROF, incorporating initial value randomization for enhanced fitting.
• Application of DROF for five-pool Lorentzian fitting, including an additional CEST at 2 ppm pool.
• Evaluation using simulated data and in vivo human data at 3 Tesla, compared to existing techniques.

Main Results:

• DROF demonstrated improved specificity and stability in CEST quantification at 3 Tesla.
• The proposed evaluation framework provided a robust assessment of CEST analysis methods.
• DROF outperformed existing methods in accuracy and robustness for CEST analysis.

Conclusions:

• DROF offers a more accurate and stable approach for CEST analysis at 3 Tesla MRI.
• The method has the potential to significantly enhance the applicability of CEST imaging.
• Further validation may confirm DROF as a valuable tool for quantitative CEST MRI.