Noninvasive Quantification Of Cerebral Blood Flow Using Phase-Contrast Magnetic Resonance Angiography

Purpose: Noninvasive quantification of cerebral blood flow using phase-contrast magneticresonance angiography (PC MRA) has been wildly applicated in experiment and clinics. However, most of the results are conflicted due to lack of standardized protocol. The blood flow volume (BFV) of the common carotid artery (CCA) is equal to the sum of BFV in the ipsilateral internal carotid artery (ICA) and external carotid artery (ECA) in theory (internal standard). The purpose of this study is to construct a reasonable protocol by choicing a range of velocity enconding and then demonstrate the discrepancy of cerebral BFV estimation with PC MRA by using the "internal" standard.Methods: The methods of this study were divided by two steps. The first step was to optimalthe velocity encoding (Venc) for cerebral BFV quantification: Ten healthy volunteers were examined using an axial two-dimensional cardiac gated PC MRA sequence centered on the second cervical vertebral body. Velocity encoding (Venc) was set from 30 to 90 cm/sec at 10cm/sec interval for total of 7 scans per volunteer. Arterial inflow, venous outflow, peak velocity, and mean velocity were obtained for the internal carotid artery (ICA), vertebral artery (VA), and jugular vein (JV) bilaterally. The second step was to evaluate the accuracy of cerebral BFV measurement by using 2D PC MRA: 20 groups of the common (CCA), internal (ICA), and external (ECA) carotid arteries in 10 healthy subjects (8 women, 2 men, age range 20 to 50 years) were examined with 2D PC MRA guided by 3D TOF MR angiograms. The sum BFV of the internal and external carotid arteries was then compared with the ipsilateral common carotid artery flow. An accurate technique would demonstrate no difference. The difference was therefore a measure of accuracy of the method.Results: In the first step, the aliasing in bilateral internal carotid arteries and vertebral arteries...