A Standardized Parameter-Free Algorithm for Combined Intravoxel Incoherent Motion and Diffusion Kurtosis Analysis of...

Area of Science:

• Magnetic Resonance Imaging
• Diffusion MRI Analysis
• Quantitative Imaging

Background:

• Diffusion MRI is crucial for tissue characterization.
• Intravoxel incoherent motion (IVIM) and diffusion kurtosis imaging (DKI) models offer complementary information.
• Accurate separation of IVIM and DKI effects is challenging.

Purpose of the Study:

• To implement and evaluate a novel parameter-free segmented algorithm for diffusion MRI analysis.
• To compare a combined IVIM-DKI model with the standard IVIM model.
• To assess the algorithm's performance in separating diffusion kurtosis from IVIM effects.

Main Methods:

• A multistep algorithm using an adaptive b-value threshold was developed.
• The algorithm separates diffusion kurtosis (high b-values) from IVIM (low b-values) effects.
• Model selection was based on the Akaike information criterion; tested on upper abdomen diffusion data from 8 healthy volunteers.

Main Results:

• The proposed algorithm successfully fitted signal decay in all assessed organs (P < 0.03).
• The IVIM-DKI model significantly increased pure diffusion and pseudodiffusion coefficients (P < 0.03).
• Perfusion fraction decreased in liver, pancreas, renal cortex, and skeletal muscle (P < 0.02) with IVIM-DKI.

Conclusions:

• The novel algorithm effectively separates IVIM and kurtosis effects in diffusion MRI.
• It provides a parameter-free approach adaptable across different organs.
• This method enhances the accuracy of diffusion MRI parameter estimation.