Radiological and anatomical evaluation of the internal venous system in the context of access to the third ventricle - proposal of a new classification

Abstract

Background

The internal venous system of the brain is a crucial anatomical landmark during accesses to the third ventricle through the foramen of Monro. Many classifications based on radiological assessment of the system have been developed, but they tend to be descriptive and do not highlight favorable anatomical variants. The aim of our study was to create a system based on morphometric measurements to facilitate preoperative decision-making regarding access to third ventricle tumors.

Methods

We conducted an analysis of 119 MRI scans with SWI sequence using BrainLab software to create a model of the ventricular system, which allowed us to perform radiological measurements. We then validated these findings anatomically using 32 human brain specimens. The analyzed structures included the foramen of Monro (FM), the anterior septal vein (ASV), the thalamostriate vein (TSV), the venous angle (VA), the internal cerebral vein (ICV), and the distance between the FM and VA.

Results

Based on the radiological analysis, we identified 9 internal venous systems, accounting for variations in each analyzed structure. The statistical analysis revealed no differences in the frequency of subtypes between radiological and anatomical studies (p = 0.097), nor in the occurrence of false venous angles (p = 0.520). We identified venous configurations that, in our assessment, are unfavorable in the context of accessing the third ventricle.

Conclusion

The resulting classification accounts for significant clinical anatomical variations and, for the first time, provides specific morphometric values for each anatomical subtype. Consequently, it serves as a reproducible reference framework for preoperative planning of access to the third ventricle.