VarioGuide: A new frameless image-guided stereotactic system - Accuracy study and clinical assessment

OBJECTIVE: VarioGuide (BrainLAB AG, Feldkirchen, Germany) is a new system for frameless image-guided stereotaxy. In the present study, we aimed to assess target point accuracy in a laboratory setting and the clinical feasibility of the system. METHODS: Using the phantom of our frame-based stereotactic system (Riechert-Mundinger; Inomed Medizintechnik GmbH, Teningen, Germany), target points were approached from different angles with the frameless system. Target point deviation in the x, y, and zplanes was assessed. Furthermore, patients harboring intracranial lesions were diagnostically biopsied using VarioGuide. RESULTS: Phantom- based accuracy measurements yielded a mean target point deviation of 0.7 mm. Between February 2007 and April 2008, 27 patients were diagnostically biopsied. Lesion volumes ranged from 0.2 to 117.6 cm³, trajectory length ranged from 25.3 to 64.1 mm, and the diagnostic yield was 93%. CONCLUSION: Concluding from the phantom measurements with ideal image-object registration, assumed spherical lesions with a volume of 0.524 cm³ can be biopsied with 100% target localization. Early clinical data revealed VarioGuide to be safe and accurate for lesions of 0.2 cm ³ and larger. Thereby, the system seems feasible for the biopsy of most intracranial lesions.