Minimally invasive neurosurgery within a 0.5 tesla intraoperative magnetic resonance scanner using an off-line neuro-navigation system.

BACKGROUND AND PURPOSE: We evaluated an advanced concept for patient-based navigation during minimally invasive neurosurgical procedures. METHODS: An infrared-based, off-line neuro-navigation system (LOCALITE, Bonn, Germany) was applied during operations within a 0.5 T intraoperative MRI scanner (iMRI) (Signa SF, GE Medical Systems, Milwaukee, WI, USA) in addition to the conventional real-time system. The three-dimensional (3D) data set was acquired intraoperatively and up-dated when brain-shift was suspected. Twenty-three patients with subcortical lesions were operated upon with the aim to minimise the operative trauma. RESULTS: Small craniotomies (median diameter 30 mm, mean diameter 27 mm) could be placed exactly. In all cases, the primary goal of the operation (total resection or biopsy) was achieved in a straightforward procedure without permanent morbidity. The navigation system could be easily used without technical problems. In contrast to the real-time navigation mode of the MR system, the higher quality as well as the real-time display of the MR images reconstructed from the 3D reference data provided sufficient visual-manual coordination. CONCLUSION: The system combines the advantages of conventional neuro-navigation with the ability to adapt intraoperatively to the continuously changing anatomy. Thus, small and/or deep lesions can be operated upon in straightforward minimally invasive operations.

[First clinical experience with extended planning and navigation in an interventional MRI unit]. / Erste klinische Erfahrungen mit einer erweiterten Eingriffsplanung und Navigation am interventionellen MRT.

PURPOSE: To present an advanced concept for patient-based navigation and to report on our first clinical experience with interventions in the cranium, of soft-tissue structures (breast, liver) and in the musculoskeletal system. MATERIALS AND METHODS: A PC-based navigation system was integrated into an existing interventional MRI environment. Intraoperatively acquired 3D data were used for interventional planning. The information content of these reference data was increased by integration of additional image modalities (e. g., fMRI, CT) and by color display of areas with early contrast media enhancement. Within 18 months, the system was used in 123 patients undergoing interventions in different anatomic regions (brain: 64, paranasal sinus: 9, breast: 20, liver: 17, bone: 9, muscle: 4). The mean duration of 64 brain interventions was compared with that of 36 procedures using the scanner's standard navigation. RESULTS: In contrast with the continuous scanning mode of the MR system (0.25 fps), the higher quality as well as the real time display (4 fps) of the MR images reconstructed from the 3D reference data allowed adequate hand-eye coordination. With our system, patient movement and tissue shifts could be immediately detected intraoperatively, and, in contrast to the standard procedure, navigation safely resumed after updating the reference data. The navigation system was characterized by good stability, efficient system integration and easy usability. Despite additional working steps still to be optimized, the duration of the image-guided brain tumor resections was not significantly longer. CONCLUSION: The presented system combines the advantage of intraoperative MRI with established visualization, planning, and real time capabilities of neuronavigation and can be efficiently applied in a broad range of non-neurosurgical interventions.