Imaging of the septum pellucidum: normal, variants and pathology

The septum pellucidum is a largely neglected anatomical midline structure during post-natal neuroimaging interpretation. Conversely, it is one of the anatomical landmarks used on pre-natal ultrasound to access normal midline formation. Because of its importance during the pre-natal period, the awareness of its primary malformative abnormalities is much higher than its disruptive acquired pathologies, often leading the misinterpretation. In this article, we will review the normal septum pellucidum formation, anatomy, and anatomical variants and will describe the imaging findings in primary malformative and secondary disruptive abnormalities affecting the septum pellucidum.