Optimized analytical segmented method for improved intravoxel incoherent motion parameter extraction in low-perfused...

Area of Science:

• Biomedical Imaging
• Diffusion MRI
• Quantitative Imaging

Background:

• Intravoxel incoherent motion (IVIM) diffusion-weighted imaging is crucial for assessing tissue perfusion and diffusion.
• Limited signal in low-perfused tissues challenges accurate IVIM parameter measurement.
• Existing segmented (S), oversegmented (OS), and analytical segmented (AS) fitting methods have limitations.

Purpose of the Study:

• To introduce and evaluate an optimized analytical segmented (opAS) method for IVIM parameter extraction.
• To compare the performance of opAS against S, OS, and AS methods.
• To assess the sensitivity of these methods in detecting perfusion changes in ischemic tissues.

Main Methods:

• Numerical simulations were conducted to compare accuracy and precision of the four fitting methods across various signal-to-noise ratio (SNR) levels and parameter combinations.
• Retrospective analysis of IVIM data from 11 piglets with induced bone marrow ischemia was performed.
• The methods' ability to detect differences in perfusion between ischemic and perfused femoral heads was evaluated.

Main Results:

• The opAS method demonstrated the lowest errors in estimating diffusion (D), pseudo-diffusion fraction (f), and pseudo-diffusion coefficient (D*) in simulations, particularly for low f and D* values.
• In vivo, all methods detected increased D and decreased f and f × D* in ischemic compared to perfused femoral heads.
• Only AS and opAS methods consistently detected decreased D* in ischemic regions.

Conclusions:

• The opAS method offers superior accuracy for IVIM parameter estimation compared to S, OS, and AS methods.
• opAS is particularly advantageous for accurately quantifying perfusion-related parameters (D* and f) in low-perfusion states.
• This optimized method enhances the reliability of IVIM for studying tissue perfusion dynamics.