Partial volume correction for quantitative CEST imaging of acute ischemic stroke

Area of Science:

• Biomedical Imaging
• Magnetic Resonance Imaging
• Quantitative MRI

Background:

• Cerebrospinal fluid (CSF) dilution effects are not accounted for in standard Amide Proton Transfer (APT) chemical exchange saturation transfer (CEST) quantification.
• Correcting for CSF dilution may enhance the robustness of CEST signal measurements.
• Partial volume effects can influence the accuracy of quantitative MRI techniques.

Purpose of the Study:

• To compare the robustness of a partial volume (PV) correction model against a standard 4-pool model for quantifying APT CEST effects.
• To evaluate the ability of these models to quantify CEST effects in healthy, normal, and pathological tissues.
• To assess the impact of PV correction on repeatability and pathological tissue contrast.

Main Methods:

• Retrospective analysis of MRI data from 12 ischemic stroke patients and 6 healthy subjects.
• Comparison of CEST signals derived from a 4-pool model and a PV correction model.
• Assessment of PV correction effects across high, low, and whole-slice tissue partial volume estimates (PVE).

Main Results:

• PV correction did not significantly alter absolute $$ in high PVE voxels.
• The PV correction model showed decreased ischemic core signal in low PVE voxels.
• PVC measures demonstrated higher repeatability (2.4%) compared to the 4-pool model (3.4%) in healthy subjects, with similar ischemic core CNR.

Conclusions:

• PV correction provides a more repeatable measure of APT effects than standard 4-pool analysis.
• PV-corrected analysis achieves similar contrast in pathological tissue.
• PV-corrected analysis is more robust, particularly at low tissue PVE values.