Markus Finke

Robot-assisted image-guided transcranial magnetic stimulation for somatotopic mapping of the motor cortex: a clinical pilot study.

PurposeShape and exact location of motor cortical areas varies among individuals. The exact knowledge of these locations is crucial for planning of neurosurgical procedures. In this study, we have used robot-assisted image-guided transcranial magnetic stimulation (Ri-TMS) to elicit MEP response recorded for individual muscles and reconstruct functional motor maps of the primary motor cortex.MethodsOne healthy volunteer and five patients with intracranial tumors neighboring the precentral gyrus were selected for this pilot study. Conventional MRI and fMRI were obtained. Transcranial magnetic stimulation was performed using a MagPro X100 stimulator and a standard figure-of-eight coil positioned by an Adept Viper s850 robot. The fMRI activation/Ri-TMS response pattern were compared. In two cases, Ri-TMS was additionally compared to intraoperative direct electrical cortical stimulation.ResultsMaximal MEP response of the m. abductor digiti minimi was located in an area corresponding to the “hand knob” of the precentral gyrus for both hemispheres. Repeated Ri-TMS measurements showed a high reproducibility. Simultaneous registration of the MEP response for m. brachioradialis, m. abductor pollicis brevis, and m. abductor digiti minimi demonstrated individual peak areas of maximal MEP response for the individual muscle groups. Ri-TMS mapping was compared to the corresponding fMRI studies. The areas of maximal MEP response localized within the “finger tapping” activated areas by fMRI in all six individuals.ConclusionsRi-TMS is suitable for high resolution non-invasive preoperative somatotopic mapping of the motor cortex. Ri-TMS may help in the planning of neurosurgical procedures and may be directly used in navigation systems.

Hey, I'm over here - How can a robot attract people's attention?

This paper describes how sonar sensors can be used to recognize human movements. The robot distinguishes objects from humans by assuming that only people move by themselves. Two methods using either rules or hidden Markov models are described. The robot classifies different movements to provide a basis for judging if a person is interested in an interaction. A comparison of two experiment results is presented. The use of orienting cues by the robot in response to detected human movement for eliciting interaction is also studied.

Evaluation of a Completely Robotized Neurosurgical Operating Microscope

BACKGROUND Operating microscopes are essential for most neurosurgical procedures. Modern robot-assisted controls offer new possibilities, combining the advantages of conventional and automated systems. OBJECTIVE We evaluated the prototype of a completely robotized operating microscope with an integrated optical coherence tomography module. METHODS A standard operating microscope was fitted with motors and control instruments, with the manual control mode and balance preserved. In the robot mode, the microscope was steered by a remote control that could be fixed to a surgical instrument. External encoders and accelerometers tracked microscope movements. The microscope was additionally fitted with an optical coherence tomography-scanning module. RESULTS The robotized microscope was tested on model systems. It could be freely positioned, without forcing the surgeon to take the hands from the instruments or avert the eyes from the oculars. Positioning error was about 1 mm, and vibration faded in 1 second. Tracking of microscope movements, combined with an autofocus function, allowed determination of the focus position within the 3-dimensional space. This constituted a second loop of navigation independent from conventional infrared reflector-based techniques. In the robot mode, automated optical coherence tomography scanning of large surface areas was feasible. CONCLUSION The prototype of a robotized optical coherence tomography-integrated operating microscope combines the advantages of a conventional manually controlled operating microscope with a remote-controlled positioning aid and a self-navigating microscope system that performs automated positioning tasks such as surface scans. This demonstrates that, in the future, operating microscopes may be used to acquire intraoperative spatial data, volume changes, and structural data of brain or brain tumor tissue.

Automatic scanning of large tissue areas in neurosurgery using optical coherence tomography

With its high spatial and temporal resolution, optical coherence tomography (OCT) is an ideal modality for intra‐operative imaging. One possible application is to detect tumour invaded tissue in neurosurgery, e.g. during complete resection of glioblastoma. Ideally, the whole resection cavity is scanned. However, OCT is limited to a small field of view (FOV) and scanning perpendicular to the tissue surface.

Motorization of a surgical microscope for intra-operative navigation and intuitive control

During surgical procedures, various medical systems, e.g. microscope or C‐arm, are used. Their precise and repeatable manual positioning can be very cumbersome and interrupts the surgeons work flow. Robotized systems can assist the surgeon but they require suitable kinematics and control. However, positioning must be fast, flexible and intuitive.

Brain-mapping using robotized TMS

We present first results of brain-mapping using robotic Transcranial Magnetic Stimulation. This non-invasive procedure enables the reliable detection of the representation of indiviual muscles or muscle groups in the motor-cortex. The accuracy is only exceeded by direct electrical stimulation of the brain during surgery. Brain-mapping using robotic TMS can also be used to detect displacements of brain regions caused by tumors. The advantage of TMS is that it is non-invasive. In this study, we compare results from statistical mapping with robotic TMS to results achived from direct stimulation done during tumor surgery. To our knowledge this is the first study of this type. We mapped the representation of three muscle groups (forearm, pinky and thumb) in tumor patients with the robot-aided TMS protocoll and with direct stimulation. The resulting maps agree within 5mm.

Brain mapping with transcranial magnetic stimulation using a refined correlation ratio and Kendall's τ

Transcranial magnetic stimulation provides a mean to stimulate the brain non-invasively and painlessly. The effect of the stimulation hereby depends on the stimulation coil used and on its placement. This paper presents a mapping algorithm based on the assumption of a monotonous functional relationship between the applied electric field strength at the representation point of a muscle and the evoked motor potential. We combine data from coil characteristics, coil placement, and stimulation outcome to calculate a likelihood map for the representation of stimulated muscles in the brain. Hereby, correlation ratio (CR) and Kendalls rank coefficient tau are used to find areas in the brain where there is most likely a functional or monotonous relationship between electric field strength applied to this area and the muscle response. First results show a good accordance of our method with mapping from functional magnetic resonance imaging. In our case, classical evaluation of CR with binning is impossible, because sample data sets are too small and data are continuous. We therefore introduce a refined CR formula based on a Parzen windowing of the X-data to solve the problem. In contrast to usual windowing approaches, which require numeric integration, it can be evaluated directly in O(n2) time. Hence, its advantage lies in fast evaluation while maintaining robust applicability to small sample sets. We suggest that the presented formula can generally be used in CR-related problems where sample size is small and data range is continuous.

Kinematics of a robotized operation microscope

We present the methods for calculating the forward and inverse kinematics of a fully motorized operation microscope. With these procedures the handling of the microscope in the surgical theatre can be facilitated. Computer-controlled positioning simplifies the pivotation around a defined focus point, improves its accuracy and makes the handling intuitive. The kinematics calculations enable new functions, such as automatic alignment of the microscope at the desired position or following a trajectory of previously chosen points.

Usability of a robotic surgical microscope

During surgical procedures, various medical systems (e.g. microscope or C-arm) are used. Their precise and repeatable manual positioning can be very cumbersome and interrupts the surgeons workflow. Robotized systems can assist the surgeon but they require suitable kinematics and control. However, positioning must be fast, flexible and intuitive.

3D Simulation of a Motorized Operation Microscope

We present a 3D-simulation which is used to develop automatic applications for a motorized operation microscope. It is implemented using java and java3d and enables a hardware independent evaluation of the system by the manufacturer as well as the user. An easy switch-over from simulation to the real system is possible because of software interfaces which are used to separate input and output methods. The simulation is also used to specify the parameters of the motorisation so that the microscope can be positioned accurately.