Fusion MRI imaging and Virtual Cisternography in neurovascular conflicts

Introduction. Neurovascular conflicts are cranial nervedysfunction syndromes caused by an abnormal contactbetween cranial nerves and arterial or venous vessels.Magnetic Resonance Imaging (MRI) has a fundamentalrole in the neuroradiological diagnosis of neurovascu-lar conflicts. 3D Constructive Interference in Steady-State (CISS) and 3D Time-of-Flight (TOF) sequences canbe considered today as the traditional imaging to assessthe anatomic relationship between cranial nerves andvessels within the cisternal spaces of the skull base.These three-dimensional techniques allow to obtain alarge number of thin source images characterized byhigh spatial and contrast resolution. New possibilitiesare related to “virtual” MRI techniques, like 3D CISS and3D-TOF Fusion Image and MR Cisternography, whichhave profoundly changed the diagnostic approach toneurovascular conflict.Object. Aim of the study was the evaluation of Magne-tic Resonance virtual techniques advantages and limitsin planning surgery for microvascular decompressionin patients with neurovascular conflict.Materials and Methods. Between December 2010 andMay 2012, we prospectively studied 32 patients (30with trigeminal neuralgia and 2 with hemifacial spasm),with a suspected clinical diagnosis of neurovascular conflict. To assess the contact between nerves andvessels, CISS and TOF sequences were used in all cases.Moreover, we performed presurgical simulation of mi-crovascular decompression using 3D-CISS and 3D-TOFimage fusion and virtual cisternography. Neuroradiolo-gical findings were compared with surgical findings.Results and Conclusions. In all cases, we demonstra-ted the anatomic relations between cranial nerves andoffending vessels with an optimal correlation betweenradiological and surgical patterns. The position of othercritical structures like the petrosal vein, the vertebralartery and the cerebellar flocculus was adequately pre-dicted.Advanced virtual MRI techniques, such as Image Fusionand Virtual Cisternography, are able to depict the com-plex anatomic relationships between neurovascularstructures within the cisternal spaces of the skull base.These techniques can be considered an optimal presur-gical tool which supports the traditional MRI study ofthis region and allows the simulation of the surgicalapproach, limiting cerebellar injury and predicting theposition of critical neurovascular structures.The ability to view this complex anatomic region in acolored image increases, in our opinion, the diagnosticconfidence in patients with neurovascular conflict.