Reproducibility and Repeatability of Intravoxel Incoherent Motion MRI Acquisition Methods in Liver.

Area of Science:

• Radiology and Medical Imaging
• Biophysics
• Gastroenterology

Background:

• Intravoxel incoherent motion (IVIM) diffusion-weighted MRI (DWI) shows promise for assessing hepatic fibrosis.
• However, variations in image acquisition techniques can impact the reliability of IVIM diffusion parameter estimates.
• Standard echo-planar imaging (EPI) may introduce distortions and variability in abdominal DWI.

Purpose of the Study:

• To minimize variability and maximize repeatability in abdominal DWI IVIM parameter estimation.
• To compare image quality and diffusion parameter repeatability between simultaneous multislice (SMS) and conventional EPI sequences.
• To optimize DWI acquisition techniques for reliable hepatic fibrosis assessment.

Main Methods:

• Prospective test-retest study comparing SMS and EPI DWI sequences with different respiratory triggering methods (breath-holding, navigator echo, respiratory triggering) at 3 Tesla.
• Analysis of IVIM parameters (fast-diffusion coefficient Df, fraction of fast diffusion f, slow-diffusion coefficient Ds) using a biexponential model.
• Evaluation of scan time, estimated signal-to-noise ratio (eSNR), and distortion ratios.

Main Results:

• Simultaneous multislice (SMS) acquisitions demonstrated significantly lower within-subject coefficients of variation (CoVs) for f and Ds compared to EPI.
• SMS techniques, particularly SMS-RT-HI, showed higher inter-observer agreement (ICC) for Ds estimation.
• SMS sequences offered higher eSNR, reduced distortion in the liver, and shorter scan times compared to EPI.

Conclusions:

• Simultaneous multislice (SMS) DWI acquisitions significantly reduce variability and improve repeatability for IVIM parameter estimation in the abdomen.
• SMS DWI provides superior image quality with higher eSNR and less distortion, making it advantageous for hepatic fibrosis assessment.
• The findings support SMS DWI as a more reliable and efficient technique for quantitative abdominal MRI compared to conventional EPI.