Highly accelerated chemical exchange saturation transfer (CEST) measurements with linear algebraic modeling

Area of Science:

• Magnetic Resonance Imaging
• Biomedical Engineering
• Medical Physics

Background:

• Chemical Exchange Saturation Transfer (CEST) imaging is valuable for evaluating diagnostic markers in clinical studies.
• Conventional CEST methods can be time-consuming, limiting their widespread clinical adoption.
• Compartmental average CEST measurements may be sufficient for diagnostic purposes, offering an alternative to voxel-by-voxel analysis.

Purpose of the Study:

• To evaluate the feasibility of adapting Spectroscopy with Linear Algebraic Modeling (SLAM) for accelerated CEST acquisitions.
• To determine if SLAM can provide accurate compartmental CEST measures with significantly reduced scan times.
• To assess the potential of SLAM-CEST in clinical settings where scan time is a constraint.

Main Methods:

• SLAM was applied to CEST k-space data from seven brain tumor patients with acceleration factors ranging from R=1 to R=45.
• Compartments were segmented from co-registered anatomical images.
• SLAM-CEST measures were compared against conventional Fourier Transform (FT) CEST average values within the same compartments.

Main Results:

• SLAM-CEST generated z-spectra comparable to conventional FT-CEST for acceleration factors up to R=45.
• High correlation (r² ≥ 0.98 for R≤9, r² ≥ 0.995 for R≤45) was observed between SLAM-CEST and FT-CEST measures at ±3.5 ppm.
• The average error for SLAM-CEST compared to FT-CEST was ≤10% for R≤45, even with minimal k-space data acquisition.

Conclusions:

• SLAM-CEST provides quantitatively equivalent results to conventional CEST up to 45 times faster.
• This accelerated acquisition method holds significant potential for clinical applications, especially in time-constrained scenarios.
• SLAM-CEST enables efficient and accurate compartmental CEST measurements, facilitating broader clinical use.