Use of Frameless Stereotactic Navigation System Combined with Intraoperative Magnetic Resonance Imaging and 5-Aminolevulinic Acid

Abstract

We have described the integrated use of a neuronavigation-guided system for frameless stereotaxy (VarioGuide [Brainlab AG, Munich, Germany]) with intraoperative magnetic resonance imaging (iMRI) and 5-aminolevulinic acid (5-ALA) and report the advantages and disadvantages that the use of these tools together can have in the treatment of various types of intracerebral lesions. After the skin incision, creation of a burr hole at the entry point, and dura opening, the VarioGuide procedure was started. Initially, the wizard software will require positioning of the stereotactic arm over the burr hole and provides feedback regarding the correct position. The procedure is performed in an iMRI theater furnished with a surgical microscope (Kinevo [Carl Zeiss AG, Oberkochen, Germany]) supplied with a violet-blue excitation light for 5-ALA fluorescence. At the end of the surgery, iMRI was performed. We present 2 exemplary cases to describe the application and workflow of these tools. When used for traditional biopsy, the possibility of performing a new iMRI scan could be of paramount importance because the brain shift can be compensated for and an alternative trajectory can be calculated from the new images and fiber tracking reconstruction. The fluorescence of the tissue sample examined under the microscope filter can provide immediate information about the nature of the lesion, allowing for the possibility of converting the procedure to open craniotomy and tumor removal. The use of combination frameless stereotaxy with iMRI and 5-ALA has shown benefits in terms of safety and precision. Moreover, the use of these tools can simplify tumor removal after simple biopsy, widening the spectrum of indications.