Real time three-dimensional image rendering in suboccipital approaches to the skull base

摘要

The neurosurgeon's orientation in approaches to the skull base depends on mental reconstruction of complex anatomical structures from tri-axial images with few visible landmarks. The study was carried out to define a protocol for intraoperative 3D navigation for the standard retrosigmoid approach. A CT sequence was combined with an intravenous CT angiography in a total of 82 patients suffering from a variety of tumors in the posterior cranial fossa. Volumetric image rendering was employed to reconstruct the intracranial vasculature and the skull bone. By fine-tuned opacity modulation of the bone it was possible to gradually "look through" the bone on dural venous structures in 3D images (CBYON~R suite). The transverse-sigmoid transition and its relation to the asterion on the surface of the skull could be visualized in a single image. The location of these key structures was drawn to the skin to custom-tailor the incision. Major emissary veins could be followed in 3D images. The asterion proved to be as far as 13 mm off the transverse-sigmoid transition. Our current protocol provides real-time 3D images that closely match individual patient anatomy. For the retrosigmoid approach, this technology offers a small but significant improvement in safety, speed and quality.