Navigated interventions in the head and neck area: standardized assessment of a new handy field generator

Electromagnetic (EM) tracking enables localization of surgical instruments within the magnetic field emitted by an EM field generator (FG). Usually, the larger a FG is, the larger its tracking volume is. However, the company NDI (Northern Digital Inc., Waterloo, ON, Canada) recently introduced the Planar 10-11 FG, which combines a compact construction (97mm x 112mm x 31mm) with a relatively large, cylindrical tracking volume (diameter: 340mm, height: 340mm). Using the standardized assessment protocol of Hummel et al., the FG was tested with regard to its tracking accuracy and to its robustness with respect to external sources of disturbance. The mean positional error (5cm distance metric according to Hummel protocol) was 0.59mm, with a mean jitter of 0.26mm in the standard setup. The mean orientational error was found to be 0.10{\deg}. The highest positional error (4.82mm) due to metallic sources of disturbance was caused by the steel SST 303. In contrast, steel SST 416 caused the lowest positional error (0.10mm). Overall, the Planar 10-11 FG tends to achieve better tracking accuracy results compared to other NDI FGs. Due to its compact construction and portability, the FG could contribute to increased clinical use of EM tracking systems.Comment: This is the preprint version of the BVM paper already published in the conference proceedings of "Bildverarbeitung in der Medizin 2019". Paper written in Germa

Pre-hospital detection of acute ischemic stroke secondary to emergent large vessel occlusion: lessons learned from electrocardiogram and acute myocardial infarction

Currently, there is no device capable of detecting acute ischemic stroke (AIS) secondary to emergent large vessel occlusion (ELVO) in the pre-hospital setting. The inability to reliably identify patients that would benefit from primary treatment with endovascular thrombectomy remains an important limitation to optimizing emergency medical services (EMS) triage models and time-to-treatment. Several clinical grading scales that rely solely on clinical examination have been proposed and have demonstrated only moderate predictive ability for ELVO. Consequently, a technology capable of detecting ELVO in the pre-hospital setting would be of great benefit. An analogous scenario existed decades ago, in which pre-hospital detection of acute myocardial infarction (AMI) was unreliable until the emergence of the 12-lead ECG and its adoption by EMS providers. This review details the implementation of pre-hospital ECG (PHECG) for the detection of AMI and explores how early experience with PHECG may be applied to ELVO detection devices, once they become available.</jats:p

Republished: Intracavitary ultrasound (ICARUS): a neuroendoscopic adaptation of intravascular ultrasound for intracerebral hemorrhage evacuation

Neurosurgeons performing intracerebral hemorrhage evacuation procedures have limited options for monitoring hematoma evacuation and assessing residual hematoma burden intraoperatively. Here, we report the successful neuroendoscopic adaptation of intravascular ultrasound, referred to here as intracavitary ultrasound (ICARUS), in two patients. Pre-evacuation ICARUS demonstrated dense hematomas in both patients. Post-evacuation ICARUS in patient 1 demonstrated significant reduction in clot burden and two focal hyperechoic regions consistent with pockets of hematoma not previously seen with the endoscope or burr hole ultrasound. These areas were directly targeted and resected with the endoscope and suction device. Post-evacuation ICARUS in patient 2 showed significant reduction of hematoma volume without indication of residual blood. ICARUS findings were confirmed on intraoperative DynaCT and postoperative CT 24 hours later. ICARUS is feasibly performed in a hematoma cavity both before and after hematoma aspiration. ICARUS may provide additional information to the operating surgeon and assist in maximizing hematoma removal.</jats:p

The bumper technique for advancing a large profile microcatheter

Operators commonly encounter difficulty maneuvering a microcatheter beyond the distal lip of wide neck aneurysms and aneurysms in challenging locations. Few techniques have been described to guide operators in these particular situations. In this case report of a 56-year-old woman with a 16 mm ophthalmic artery aneurysm, the microcatheter continually snagged the distal aneurysm lip, preventing delivery of a flow diverter into the distal parent vessel. In troubleshooting this obstacle, a second microguidewire was introduced alongside the microcatheter and was used to cover the distal lip of the aneurysm to prevent further snagging. The second guidewire successfully deflected the microcatheter into the distal vessel, a technique that we have aptly dubbed the ‘bumper technique’

A review and comparison of three neuronavigation systems for minimally invasive intracerebral hemorrhage evacuation

Advances in stereotactic navigation technology have helped to improve the ease, reliability, and workflow of neurosurgical intraoperative navigation. These advances have also allowed novel, minimally invasive neurosurgical techniques to emerge. Minimally invasive techniques for intracerebral hemorrhage (ICH) evacuation, including endoscopic evacuation and passive catheter drainage, are notable examples, and as these gain support in the literature and their use expands, stereotactic navigation will take on an increasingly important and central role. Each neurosurgical navigation system has unique characteristics. Operators may find that certain aspects are more important than others, depending on the environment in which the evacuation is performed and operator preferences. This review will describe the characteristics of three popular stereotactic neuronavigation systems and compare their advantages and disadvantages as they relate to minimally invasive ICH evacuation.</jats:p