Stereotactic guided laser-induced interstitial thermotherapy (SLITT) in gliomas with intraoperative morphologic monitoring in an open MR-unit.

Stereotactic guided laser-induced interstitial thermotherapy (SLITT) represents a minimal invasive method to produce necrosis in cerebral tumor tissue by local heating. The dose/response relationship relies on experimental studies and few clinical data performed in high field MR systems. A better understanding of the energy-dose/tissue response in human brain tumors is important to optimize this treatment modality. Twenty-four patients with gliomas were treated with SLITT, with a total of 30 laser procedures performed. Under local anesthesia 600 microns laser-fibers were inserted by stereotactic-guided technique into the center of the tumor. In a low field open MR system (0.2 T) the denaturation of the tumor using a neodymium YAG laser (1064 nm) was monitored by 3D-turbo FLASH T1-weighted sequences. Laser energy was applied in steps of 400 to 1200 Joules. Development of necrosis at a mean total energy dose of 2979 Joules could be monitored in all procedures. Two different thermal lesion architectures were observed. First signal changes were monitored after a mean of 1108 Joules and 1393 Joules, respectively. Mean max. total lesion size was 21.2 mm. The higher the total energy the larger was the thermolesion, but no linear relationship could be seen. Tumor tissue response showed no dependency on tumor grading. Monitoring of stereotactic guided laser-induced thermolesions in the low-power MR OPEN is feasible and safe. Although lesion size basically is energy dependent, it should be applied individually, since the thermal response in brain tumors varies due to different optical properties, even in the same tumor gradings.

BrainLab VectorVision Neuronavigation System: technology and clinical experiences in 131 cases.

OBJECTIVE: The BrainLab VectorVision neuronavigation system was used in 131 cases of different brain pathological conditions. The neuronavigation system was used without problems in 125 cases. These cases included 114 microsurgical operations, 4 endoscopic procedures, 4 frameless stereotactic biopsies, and 3 catheter placements. METHODS: The BrainLab VectorVision neuronavigation system is an intraoperative, image-guided, frameless, localization system. The system consists of a computer workstation for registration of images and physical spaces, an intraoperative localization device, and a computer image display. The system provides real-time responses regarding the locations of surgical instruments. VectorVision is based on passive reflections of infrared flashes. Universal adapters with reflective markers for surgical instruments, endoscopes, and the operating microscope are used. RESULTS: In six cases, the system could not be used because of system failure or mishandling. In 125 neurosurgical cases, the neuronavigation system was useful, with a target-localizing accuracy of 4+/-1.4 mm (mean+/-standard deviation). For small cerebral lesions, we never performed an exploration with negative results. CONCLUSION: The BrainLab neuronavigation system has been shown to be very helpful and user-friendly for routine neurosurgical interventions. Its advantage lies in its mobility, based on wireless reflective adapters for surgical instruments, endoscopes, and the operating microscope.

Three-dimensional computer-assisted stereotactic-guided microneurosurgery combined with cortical mapping of the motor area by direct electrostimulation.

TIM (Zeppelin Chirurgische Instrumente GmbH, 82 049 Pullach, Germany) is a tomographic imaging system which enables surgeons to visualize the pathologic lesions three dimensionally in relationship to the surrounding structures. The distance and the angle between the pathologic lesion and the anatomical and/or bony landmarks as well as the volume of the mass lesion can be measured. Therefore an accurate localization of the lesion is possible with this technique. It is very applicable for planning of surgery on skull base tumors. The surgical procedure for small and well-defined, intrinsic pathologic deep-seated brain lesions, however, becomes much easier by using the stereotactic techniques of this system. The target point and the direction brain-surface-to-lesion can be determined within seconds. Before the aiming probe is inserted to the target, the cortical motor area is mapped by direct electrical stimulation. The approach can be varied depending on the results of these neurophysiologic investigations of the brain surface. The dissection is made along the aiming probe up to the target point. Because of the fixation of the brain with the needle, a brain shifting due to the dissection as well as to CSF release is diminished. Forty patients with deep-seated intracerebral lesions were operated on during a 13 months period by these combined techniques in our service. Using this technique, we never made a negative exploration. In all but three patients, total removal of the mass lesion was achieved. Permanent neurological deficits were observed in two patients only. In our opinion, this combined imaging and neurophysiological technique is easy to perform, and of major benefit for the patients due to its accuracy and is preferable in comparison with other single computer localizer techniques without neurophysiological monitoring.