Stereotactic Systems and Procedures for Depth Electrode Placement: Technical Aspects

Abstract

The authors describe the conversion of the Leksell spherical system to that of the orthogonal approach for depth electrode placement, by the addition of relatively simple devices to the main frame. These modifications have created the need for new instrumentation such as teleradiology with laser beam centering and the use of an all-purpose stereotactic chair. The main device used for the orthogonal approach is an instrument and electrode carrier moving on sliding side bars. This system can also take advantage of the newer imaging techniques, such as CT scanning, digital angiography and NMR, by the addition of computer markers which are interchangeable with the frame side bars.

The Role of Computed Tomographic and Digital Radiographic Techniques in Stereotactic Procedures for Electrode Implantation and Mapping, and Lesion Localization

“…Analysis of the CT scans and angiogram is made possible by simple accessories which are attached to the modified Leksell frame used for stereotactic procedures [1]. These accessories consist of a pair of side plates, in which are em bedded metallic markers, the images of which are detected by the com puter in order to establish a set of coordinates related to those of the frame.…”

“…The angiograms which are used in conjunction with our stereotac tic procedures are made with a teleradiographic system (FSD 16 feet) [1] in order to minimize magnification distortion between the left and right sides of the brain. The coordinate graduations on the frame are lead-filled so they may be visualized on the angiogram film, but be cause of the small differential magnification between the images of the proximal and distal posts, and the effect of overlying contributions from the image of the patient's skull, these markings are often difficult to interpret either visually or using the computer.…”

pyElectrode: An open-source tool using structural MRI for electrode positioning and neuron mapping

“…MRI guidance was used as early as the 1980s for the stereotaxic placement of electrodes and radiosurgery probes (Olivier et al, 1983, 1987). In contrast to X-ray, this emerging method allowed the visualization of soft tissue landmarks, such as the anterior and posterior commissures, for surgical planning and execution (Villemure et al, 1987) (for a review, see (Peters, 2006)).…”