Quantification of Regional Cerebral Blood Flow Using Diffusion Imaging With Phase Contrast

Area of Science:

• Neuroimaging
• Medical Physics
• Radiology

Background:

• Perfusion-related diffusion coefficients from triexponential analysis correlate with regional cerebral blood flow (rCBF).
• Current arterial spin labeling (ASL) methods provide semiquantitative rCBF measures, limiting absolute quantification.
• Developing noninvasive techniques for accurate rCBF assessment is crucial.

Purpose of the Study:

• To introduce and validate a novel diffusion imaging with phase contrast (DPC) method for noninvasive rCBF quantification.
• To utilize total cerebral blood flow (CBF) from phase-contrast (PC) MRI to convert diffusion coefficients to absolute rCBF values.
• To compare DPC-derived rCBF with ASL and established positron emission tomography (PET) methods.

Main Methods:

• Prospective study involving eleven healthy volunteers.
• Utilized 3.0T MRI with diffusion echo-planar imaging (b-values 0-3000 s/mm²), PC-MRI, pulsed continuous ASL, and 3D T1-weighted fast field echo.
• Compared rCBF in gray matter (GM) and white matter (WM) between DPC and ASL, and validated against [15O]-water PET literature values.

Main Results:

• A significant positive correlation (R=0.9) was found between DPC and ASL rCBF in GM; correlation was poor in WM (R=0.09).
• DPC-derived rCBF values in GM and WM, and the GM/WM ratio, were consistent with [15O]-water PET literature values.
• DPC yielded significantly higher rCBF values in both GM and WM compared to ASL.

Conclusions:

• Diffusion imaging with phase contrast (DPC) enables noninvasive quantification of regional cerebral blood flow (rCBF).
• DPC provides accurate and absolute rCBF measurements, comparable to PET standards.
• This technique offers a promising advancement over semiquantitative ASL methods for rCBF assessment.