Evaluation of Whole Brain Intravoxel Incoherent Motion (IVIM) Imaging

Area of Science:

• Medical Imaging
• Neuroscience
• Biophysics

Background:

• Intravoxel Incoherent Motion (IVIM) imaging offers non-invasive measurement of tissue perfusion without contrast agents.
• Whole-brain perfusion studies often utilize an isotropic 1 mm voxel size as a standard.
• Developing a clinically viable, time-efficient, and precise whole-brain IVIM protocol is crucial.

Purpose of the Study:

• To evaluate the feasibility of high-resolution IVIM imaging for whole-brain perfusion studies.
• To assess the impact of signal-to-noise ratio (SNR) on the estimation of key IVIM parameters (S₀, f, D*, D).
• To compare the performance of different IVIM parameter estimation techniques under varying SNR conditions.

Main Methods:

• Performed IVIM MRI measurements on a 3T scanner with a 1x1x2 mm voxel size.
• Conducted simulations using MATLAB with known "ground truth" and noised data across 36 SNR levels.
• Evaluated three estimation techniques: segmented grid search, segmented curve fitting, and one-step curve fitting.

Main Results:

• High-resolution IVIM imaging of the whole brain is feasible.
• Mean relative errors for S₀, f, D*, and D using segmented grid search at expected SNR were 5.00%, 81.91%, 76.31%, and 18.34%, respectively.
• Significant variations in accuracy and precision were observed, influenced by SNR and the chosen estimation method.

Conclusions:

• The study confirms the possibility of high-resolution IVIM for whole-brain perfusion.
• The accuracy of IVIM parameter estimation is highly dependent on SNR levels.
• Method selection for parameter estimation critically impacts the reliability of IVIM results in clinical settings.