Functional MR angiography using phase contrast imaging technique at 3T MRI.

Purpose: Phase contrast magnetic resonance angiography (PC MRA) is an important, non-invasive method for obtaining quantitative information on blood flow. The purpose of the present study was to investigate the dynamic cerebral arterial response in humans to visual stimulation by quantitative velocity analysis using PC MRA.

Methods: Functional PC MRA (fPCA) images at 3 Tesla MRI were acquired with a total acquisition time of 10 m 18 s for 2 rest and 1 visual stimulation sessions using a flashing checker board. Twelve healthy subjects participated in this study. Circular regions of interest (ROIs) consisting of 21 pixels were analyzed to determine the velocity changes due to visual stimulation in selected vessel segments supplying the visual cortex. Time-of-flight (TOF) MRA and PC MRA reference volume images were then compared to measure the signal intensity and quantitative blood velocity changes in the cerebral vessels.

Results: The mean velocity changes measured by PC MRA between rest and stimulation were 0.64 and 0.42 cm/s within the peak ROI and distal ROIs of the selected blood vessels, which corresponds to a 42.9% and 30.1% increase, respectively. Both TOF MRA and PC MRA reference volume images also exhibited an increase in the signal intensity of the target vessels during stimulation.

Conclusion: This study demonstrated that fPCA could play a role in the quantitative analysis of the functional cerebral vascular response by measuring dynamic vascular changes in intensity and velocity in small arteries.