[Anatomy of the circle of Willis with 3D time of flight magnetic resonance angiography and analysis of partitions].

The purpose of this study was to analyse with 3D TOF MR angiography the anatomical variants of the circle of Willis (CW) in 109 consecutive patients. In all cases, the quality of exams was sufficient to analyse the anatomy of CW. Nevertheless, MRA over estimated hypoplastic segments because incomplete CW were more frequently demonstrated with MRA than in anatomic literature. This lack of MRA sensitivity was related to artifacts as MIP artifacts and blood flow artifacts. MRA sensitivity was improved by analysis of partitions with MIP reconstructions.