[Prevention of vascular complications in endonasal paranasal sinus surgery. Part II: Pre- and intraoperative imaging].

Computer-assisted surgery (CAS) is a new intraoperative localization system that is based on digital image generation devices. The system has been used in 189 cases of paranasal sinus procedures, employing computed tomography (CT) image data. Highly accurate imaging and localization of bony structures can be achieved in this way, although definition of vascular structures is limited by representation attributes of vessels in CT. Algorithms have now been developed for the use of magnetic resonance angiography (MRA) data with the system. CAS was used in six cases of endonasal surgery. Imaging helped substantially in all cases, but its application was limited by incomplete reflection of small vessels. In one case, intraoperative findings showed MRA-inherent inaccuracies. These might be avoided using correction programs and phantom selection (shimming) procedures in the future. Additionally, matching of different imaging modalities should improve intraoperative applications of CAS.