Impact of measurement parameters on apparent diffusion coefficient quantification in diffusion-weighted-magnetic...

Area of Science:

• Medical Imaging
• Diffusion-Weighted Imaging (DWI)
• Quantitative MRI

Background:

• Apparent diffusion coefficient (ADC) is a key MRI biomarker.
• Reproducibility of ADC measurements is critical for clinical applications.
• Understanding the impact of imaging parameters on ADC is essential.

Purpose of the Study:

• To systematically evaluate the reproducibility of DWI.
• To assess the impact of b values and echo time (TE) on ADC quantification.
• To determine the minimum upper b value for reliable ADC measurements.

Main Methods:

• Phantom studies with varying diffusivities and T2 relaxation times.
• Diffusion-weighted imaging acquired with multiple b values and TEs.
• ADC calculated using various b value combinations; reproducibility assessed via coefficient of variation (CV) and CVsta.
• Volunteer studies evaluating ADC in 7 organs.

Main Results:

• ADC reproducibility improves with higher b values and increased diffusivity.
• An upper b value of 600 s/mm provides reliable ADC results (max CVsta 7.5%).
• ADC values decrease with increasing upper b value and TE; increase with T2 relaxation time.

Conclusions:

• ADC measurements exhibit high reproducibility but are sensitive to b values and TE.
• Constant TE is recommended for consistent ADC quantification.
• An upper b value of 600 s/mm offers a balance of ADC stability, SNR, and measurement time for diverse tissues.