OBJECTIVE: This article demonstrates the usefulness and the problems o
f present-state software for virtual endoscopy as a tool for the plann
ing and simulation of minimally invasive neurosurgical procedures. MET
HODS: The software Navigator (General Electric Medical Systems, Buc, F
rance) was applied for virtual endoscopic visualization of three-dimen
sional magnetic resonance data sets of healthy volunteers and neurosur
gical patients, using a clinical magnetic resonance scanner (1.5-T Sig
na Hispeed; General Electric Medical Systems). Classical approaches fo
r minimally invasive procedures were simulated. RESULTS: Virtual endos
copy provided impressive three-dimensional views of intracranial and i
ntracerebral cavities, with visualization of many anatomic details of
the brain's inner and outer surfaces. The method proved to be especial
ly suited for the simulation and planning of operations of intraventri
cular lesions, for which the technical limitations of the present stat
e of development of this method have fewer implications. However, the
present state of technology, as described in this article, has two maj
or shortcomings: 1) the blood vessels cannot be visualized together wi
th the brain tissue and cranial nerves; and 2) different tissue compar
tments cannot be stained in their original coloring, which would facil
itate their recognition and thus orientation in space by anatomic land
marks. Another important disadvantage at this stage is time consumptio
n for many single working steps. CONCLUSION: Virtual endoscopy is a pr
omising tool for teaching and training in intracranial neuroanatomy as
well as for planning and simulation of minimally invasive (e.g., endo
scopic), mainly intraventricular, operations. Direct clinical applicat
ion is, at this stage of development, limited by several technical sho
rtcomings of visualization and quantification of distances and modelin
g of surfaces.