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Background
Intraventricular lesions are relatively rare and arise from ventricular structures such as the walls of the ventricular system, the septum pellucidum, and the choroid plexus. A number of factors assist in defining the differential diagnosis, both radiological and clinical, including where the lesion is positioned within the ventricle as well as age and any associated conditions. Using both computed tomography (CT) and magnetic resonance imaging (MRI) studies, this exhibit will highlight key features to distinguish various intraventricular pathologies through a systematic approach so that interpreting radiologists will be able to confidently identify lesions and communicate effectively with the consultant clinician.

Educational Goals / Teaching Points
Explore and learn the complex anatomy of the ventricular system and its adjacent structures. Review the diagnostic algorithm for delineating ventricular lesions. Consider the most common CT and MRI features for listed ventricular lesions

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
To truly grasp intraventricular lesions, we must first understand the flow of CSF through the ventricular system as well as some relevant anatomy. The differential depends on the location of the intraventricular lesion since these lesions tend to have a preference on where they develop. Lateral ventricles are the largest, and most proximal, ventricles in the central nervous system (CNS); interventricular foramen of Monro: Connects the lateral ventricle to the third ventricle; cerebral aqueduct of Sylvius: Connects the third ventricle to the fourth ventricle; 4th ventricle CSF will leave the 4th ventricle to the surrounding CNS tissue or to the central spinal canal; septum pelluicidum a thin transparent membrane located in the brain between the body and anterior horns of the lateral ventricles; choroid plexus located within the cerebral ventricles and is made of choroidal epithelial cells, loose connective tissue, and permeable capillaries. It produces cerebrospinal fluid. Different lesions have a predilection to specific parts of the ventricular system. The lesions commonly present with characteristic CT and MRI features.

Conclusion
Differential diagnosis for intraventricular lesions is broad and includes benign and neoplastic lesions. This exhibit provides an overview of various intraventricular lesions and how to approach their diagnosis using CT and MRI findings. The goal is a careful evaluation of imaging findings to allow for a narrow and accurate differential diagnosis and faster appropriate treatment.