ABSTRACT
Purpose To investigate the value of simultaneousnon-contrast angiographyand intra-plaquehemorrhage (SNAP) in assessing Willis circle integrity of the brain using three-dimensional time of flight (TOF) MRA as a reference. Materials and Methods According to the inclusion criteria, a total of 62 patients with stroke symptoms within 3 months were collected. All patients underwent head SNAP and TOF on Philips 3.0T MR scanner. TOF and SNAP were treated respectively at the Philips workstation using maximum and minimum intensity projections to generate non-enhanced MRA images which were, afterwards, interpreted using blind reading to determine the presence or absence of individual blood vessels in the circle of Willis. In order to assess the consistency of the interpretation, all images were interpreted again 2 weeks later to avoid memory bias. Finally, The consistency of the two interpretations was analyzed, and the ability of SNAP and TOF in evaluating the integrity of Willis circle was compared. In addition, for 15 patients with VISTA images, the plaque of Willis circle vascular wall was evaluated using SNAP and VISTA images to compare their evaluation ability. Results The results of the first and second interpretations of SNAP and TOF were highly consistent. The arteries with exactly the same interpretation included left anterior cerebral artery A1 (LA1), right anterior cerebral artery A1 (RA1), left posterior cerebral artery P1 (LP1) and right posterior cerebral artery P1 (RP1) (Kappa=1.000). The results in terms of left posterior communicating artery (LPCoA) (Kappa=0.926 and 0.924, respectively), right posterior communicating artery (RPCoA) (Kappa=0.931 and 0.732, respectively) and integrity (Kappa=0.815 and 0.816, respectively) were relatively consistent, while there was a relatively low consistency in terms of anterior communicating artery (ACoA) (Kappa=0.640 and 0.675, respectively). In evaluating the constituent vessels of the circle of Willis and its integrity, SNAP and TOF showed good consistency. Vessels with identical SNAP and TOF interpretations include LA1, RA1, LP1, and RP1 (Kappa=1.000). The interpretation consistency of the two imaging techniques on LPCoA (Kappa=0.852 and 0.848), RPCoA (Kappa=0.796 and 0.796, respectively), and integrity (Kappa=0.701 and 0.742, respectively) was relatively high. While the consistency of SNAP and TOF in terms of ACoA was slightly lower (Kappa=0.680 and 0.714, respectively). In assessing the plaque of Willis circle vascular wall, the evaluation results of SNAP and VISTA were consistent. Conclusion As a non-enhanced angiography technique, the magnetic resonance SNAP sequence can well evaluate the integrity of Willis circle, as well as the presence or absence of plaque on Willis circle vascular wall.