1. From: Advanced Cranial Navigation
FIGURE 1. Accuracy experiment. A, accuracy experiment setup. A phantom head with surface fiducial markers and central target points is mounted on a nonferromagnetic skull clamp in an intraoperative magnetic resonance suite. For electromagnetic navigation accuracy tests, the field generator (G) is positioned 25 cm from the target area, and the patient reference tracker (T) is placed in a repositioning device on the skull clamp. B, for continuous instrument navigation, the electromagnet stylet, which is a flexible wire with 2 electromagnetic field detecting coils at its tip (red bars), was introduced into a standard single-use suction.
From: Advanced Cranial Navigation
Neurosurgery. 2013;72(suppl_1):A43-A53. doi: /NEU.0b013e c03
Neurosurgery | Copyright © 2012 by the Congress of Neurological Surgeons

2. From: Advanced Cranial Navigation
FIGURE 2. Comparison of target accuracy in standard vs advanced navigation. No significant difference in target registration accuracy was noted for standard navigation (optic tracking, fiducial marker registration, pointer based) vs advanced navigation setup (electromagnetic [EM] tracking, surface merge, stylet based, instrument/suction tracking). A significant decrease in accuracy was found if the EM system was used closer to the MR magnet and after intraoperative magnetic resonance imaging with intermittent removal of the navigation equipment (P < .001).
From: Advanced Cranial Navigation
Neurosurgery. 2013;72(suppl_1):A43-A53. doi: /NEU.0b013e c03
Neurosurgery | Copyright © 2012 by the Congress of Neurological Surgeons

3. From: Advanced Cranial Navigation
FIGURE 3. Clinical examples of continuous electromagnetic (EM) instrument navigation. A, fluorescence-guided resection of a World Health Organization grade IV left parietal glioma. After removal of the macroscopic tumor bulk, fluorescence indicates further glioma tissue (left). Continuous EM suction navigation (see parallel suctions [S]) can provide a constant update on the surgeon's position related to the corticospinal tract (asterisk), can guide subcortical stimulation, and is useful to prevent inadvertent removal of eloquent white matter tracts. B, robotic resection of left frontal convexity meningioma. The surgeon controlling the robot is provided with constantly updated information about the actual position on an external navigation monitor (N; left;). For continuous EM instrument navigation, the suction device of the left robot manipulator is equipped with the EM stylet (S; right). With optimal setup, EM navigation is possible despite multiple ferromagnetic retractors close to the operating field (R). C, endoscopic transsphenoidal surgery for nonfunctioning pituitary macroadenoma: The surgeon's position is behind the patient's head. CI, clival indentation; OCR, opticocarotid recess; SF, sellar floor; TC, tuberculum sellae. After removal of the sphenoid sinus septum (SS), a landmark accuracy check is performed by pointing on the partially eroded left protuberance of the internal carotid artery (asterisk). Continuous EM multimodality navigation of the suction device proves high accuracy by depicting the current position on top of the magnetic resonance angiography (MRA) internal carotid artery (right). D, endoscopic third ventriculostomy for subacute hydrocephalus owing to aqueductal membrane (red circle). The endoscope has been advanced into the third ventricle through the foramen of Monroe by navigation guidance (left). The EM stylet is then selectively advanced to the target point between the dorsum sellae and basilar artery to perforate the floor of the third ventricle under navigation guidance (green circle; right). The multimodality navigation comprises data from computed tomography (registration, dorsum sellae), MR T2 (third ventricular floor), and MRA (basilar artery). E, endoscopic cyst wall puncture for recurrent occipital arachnoid cyst causing visual disturbances: The endoscope has been advanced into the cyst cavity via a paramedian burr hole in the trajectory of the lateral ventricle by navigation guidance. The EM stylet was then selectively advanced to the target point, and the membrane to the ventricle was perforated with navigation guidance. The resulting opening (left) was finally enlarged by a balloon catheter. F, frameless stereotactic biopsy of left periventricular MR T1 contrast-enhancing lesion. A needle positioning device was placed on the burr hole at the entry point, and a standard side-opening biopsy needle fitted with the EM stylet was advanced under continuous navigational guidance (left). Because of the small size of the lesion, computed tomography has been added to the MR navigation to increase precision (right). Note the 5-mm tip extension (yellow) to display the tip of needle and the crosshair behind to indicate the position of the side opening.
From: Advanced Cranial Navigation
Neurosurgery. 2013;72(suppl_1):A43-A53. doi: /NEU.0b013e c03
Neurosurgery | Copyright © 2012 by the Congress of Neurological Surgeons

4. From: Advanced Cranial Navigation
Neurosurgery. 2013;72(suppl_1):A43-A53. doi: /NEU.0b013e c03
Neurosurgery | Copyright © 2012 by the Congress of Neurological Surgeons