A new tool for touch-free patient registration for robot-assisted intracranial surgery: application accuracy from a phantom study and a retrospective surgical series.

OBJECTIVE The purpose of this study was to compare the accuracy of Neurolocate frameless registration system and frame-based registration for robotic stereoelectroencephalography (SEEG). METHODS The authors performed a 40-trajectory phantom laboratory study and a 127-trajectory retrospective analysis of a surgical series. The laboratory study was aimed at testing the noninferiority of the Neurolocate system. The analysis of the surgical series compared Neurolocate-based SEEG implantations with a frame-based historical control group. RESULTS The mean localization errors (LE) ± standard deviations (SD) for Neurolocate-based and frame-based trajectories were 0.67 ± 0.29 mm and 0.76 ± 0.34 mm, respectively, in the phantom study (p = 0.35). The median entry point LE was 0.59 mm (interquartile range [IQR] 0.25-0.88 mm) for Neurolocate-registration-based trajectories and 0.78 mm (IQR 0.49-1.08 mm) for frame-registration-based trajectories (p = 0.00002) in the clinical study. The median target point LE was 1.49 mm (IQR 1.06-2.4 mm) for Neurolocate-registration-based trajectories and 1.77 mm (IQR 1.25-2.5 mm) for frame-registration-based trajectories in the clinical study. All the surgical procedures were successful and uneventful. CONCLUSIONS The results of the phantom study demonstrate the noninferiority of Neurolocate frameless registration. The results of the retrospective surgical series analysis suggest that Neurolocate-based procedures can be more accurate than the frame-based ones. The safety profile of Neurolocate-based registration should be similar to that of frame-based registration. The Neurolocate system is comfortable, noninvasive, easy to use, and potentially faster than other registration devices.

Cerebral Angiography for Multimodal Surgical Planning in Epilepsy Surgery: Description of a New Three-Dimensional Technique and Literature Review.

OBJECTIVE: Cerebrovascular imaging is critical for safe and accurate planning of Stereo-ElectroEncephaloGraphy (SEEG) electrode trajectory. We developed a new technique for Cone Beam Computed Tomography (CBCT) Three-Dimensional Digital Subtraction Angiography (3D DSA). METHODS: The workflow core is the acquisition of computed tomography datasets without (bone mask) and with selective injection of contrast medium in the main brain-feeding arteries, followed by dataset registration and subtraction. The images were acquired with the O-armTM 1000 System (Medtronic). Images were postprocessed with FSL software package. We retrospectively analyzed 191 3D DSA procedures and qualitatively analyzed the quality of each 3D DSA dataset. RESULTS: The quality of 3D DSA was good in 150 procedures, sufficient in 37, and poor in 4. 3D rendering of the vascular tree was helpful for both SEEG implantation and resective surgery planning. Angiography complications occurred in only one procedure that was aborted due to a major allergic reaction to contrast medium. No other complications directly related to 3D DSA occurred. Minor intracerebral hemorrhage occurred in 2/191 patients after SEEG implantation, with no permanent sequelae. CONCLUSIONS: CBCT 3D DSA is a safe diagnostic procedure for SEEG electrode trajectory planning and for 3D reconstructions of the vascular tree in multimodal scenes for resections. The high fidelity and geometric accuracy contribute to the safety of electrode implantation.

Review of potential improvements using MRI in the radiotherapy workflow.

The goal of modern radiotherapy is to deliver a lethal amount of dose to tissue volumes that contain a significant amount of tumour cells while sparing surrounding unaffected or healthy tissue. Online image guided radiotherapy with stereotactic ultrasound, fiducial-based planar X-ray imaging or helical/conebeam CT has dramatically improved the precision of radiotherapy, with moving targets still posing some methodical problems regarding positioning. Therefore, requirements for precise target delineation and identification of functional body structures to be spared by high doses become more evident. The identification of areas of relatively radioresistant cells or areas of high tumor cell density is currently under development. This review outlines the state of the art of MRI integration into treatment planning and its importance in follow up and the quantification of biological effects. Finally the current state of the art of online imaging for patient positioning will be outlined and indications will be given what the potential of integrated radiotherapy/online MRI systems is.

Stereoelectroencephalography: surgical methodology, safety, and stereotactic application accuracy in 500 procedures.

BACKGROUND: Stereoelectroencephalography (SEEG) methodology, originally developed by Talairach and Bancaud, is progressively gaining popularity for the presurgical invasive evaluation of drug-resistant epilepsies. OBJECTIVE: To describe recent SEEG methodological implementations carried out in our center, to evaluate safety, and to analyze in vivo application accuracy in a consecutive series of 500 procedures with a total of 6496 implanted electrodes. METHODS: Four hundred nineteen procedures were performed with the traditional 2-step surgical workflow, which was modified for the subsequent 81 procedures. The new workflow entailed acquisition of brain 3-dimensional angiography and magnetic resonance imaging in frameless and markerless conditions, advanced multimodal planning, and robot-assisted implantation. Quantitative analysis for in vivo entry point and target point localization error was performed on a sub--data set of 118 procedures (1567 electrodes). RESULTS: The methodology allowed successful implantation in all cases. Major complication rate was 12 of 500 (2.4%), including 1 death for indirect morbidity. Median entry point localization error was 1.43 mm (interquartile range, 0.91-2.21 mm) with the traditional workflow and 0.78 mm (interquartile range, 0.49-1.08 mm) with the new one (P < 2.2 × 10). Median target point localization errors were 2.69 mm (interquartile range, 1.89-3.67 mm) and 1.77 mm (interquartile range, 1.25-2.51 mm; P < 2.2 × 10), respectively. CONCLUSION: SEEG is a safe and accurate procedure for the invasive assessment of the epileptogenic zone. Traditional Talairach methodology, implemented by multimodal planning and robot-assisted surgery, allows direct electrical recording from superficial and deep-seated brain structures, providing essential information in the most complex cases of drug-resistant epilepsy.

Stimulus-induced, sleep-bound, focal seizures: a case report.

STUDY OBJECTIVES: In nocturnal frontal lobe epilepsy (NFLE), seizures occur almost exclusively during NREM sleep. Why precisely these seizures are sleep-bound remains unknown. Studies of patients with nonlesional familial forms of NFLE have suggested the arousal system may play a major role in their pathogenesis. We report the case of a patient with pharmaco-resistant, probably cryptogenic form of non-familial NFLE and strictly sleep-bound seizures that could be elicited by alerting stimuli and were associated with ictal bilateral thalamic and right orbital-insular hyperperfusion on SPECT imaging. DESIGN: Case report. SETTING: University Hospital Zurich. PATIENTS OR PARTICIPANTS: One patient with pharmaco-resistant epilepsy. CONCLUSION: This case shows that the arousal system plays a fundamental role also in cryptogenic non-familial forms of NFLE.