Correcting pulse duration effects in the diffusional kurtosis of the multi-compartment Kärger model

Area of Science:

• Magnetic Resonance Imaging
• Diffusion MRI Physics
• Quantitative MRI

Background:

• Accurate estimation of diffusional kurtosis in multi-compartment models is crucial for understanding tissue microstructure.
• Non-zero pulse durations in Stejskal-Tanner diffusion-weighted imaging sequences introduce errors in kurtosis measurements.
• The Kärger model (KM) is widely used but sensitive to pulse duration artifacts.

Purpose of the Study:

• To develop and validate a method for reducing pulse duration effects on diffusional kurtosis estimation.
• To introduce an effective diffusion time correction for the multi-compartment Kärger model.
• To improve the accuracy of kurtosis measurements in diffusion MRI.

Main Methods:

• An effective diffusion time was introduced to correct for non-zero pulse duration (δ) effects in the multi-compartment Kärger model.
• The correction was evaluated for its accuracy to first order in diffusion time (Δ).
• Numerical simulations were performed for two-compartment and general multi-compartment Kärger models using Stejskal-Tanner sequences.

Main Results:

• The effective diffusion time correction significantly reduced deviations in apparent kurtosis and its time derivative for the two-compartment Kärger model.
• For the general multi-compartment Kärger model, the maximum kurtosis deviation was reduced from 2.26% to 0.57%.
• The maximum deviation in the kurtosis derivative was reduced from 46% to less than 1% after correction.

Conclusions:

• The proposed effective diffusion time correction effectively suppresses pulse duration artifacts in multi-compartment Kärger model kurtosis estimation.
• This method enhances the reliability of quantitative diffusion MRI metrics.
• The correction is vital for accurate microstructural analysis using advanced diffusion models.