ANATOMICAL VARIANTS OF CIRCLE OF WILLIS W ITH 3D TIME-OF-FLIGHT NIR ANGIOGRAPHY AND ANALYSIS OF PARTITIONS

The purpose of this study was to analyse with 3D TOF MR angiography th e 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 segme nts because incomplete CW were more frequently demonstrated with MRA t han in anatomic literature. This lack of MRA sensitivity was related t o artifacts as MIP artifacts and blood flow artifacts. MRA sensitivity was improved by analysis of partitions with MIP reconstructions .