MRI findings in patients with central neurocytomas with special reference to differential diagnosis from other ventricular tumours near the foramen of Monro.

We retrospectively evaluated 12 patients with histologically verified central neurocytoma (CN) to identify the MRI characteristics associated with this tumour. All tumours had heterogeneous signal intensity in their solid components and seven had a "soap bubble" or spongy appearance. Spicules were identified at the tumour periphery interfacing with the lateral ventricular walls. These spicules were formed by walls of multiple cysts of medium size. Undulation of the lateral ventricular wall attached to the tumour capsule was seen in nine patients. These spicules and undulations resulted in a "scalloping" appearance. In a diagnostic experiment to test the differential diagnosis of CN from other neoplasms near the foramen of Monro, the identification of scalloping made a greater contribution to the specificity and accuracy of the diagnosis than the soap bubble appearance. Thus, recognition of multiple cystic interfaces between the solid part of the tumour and the lateral ventricular wall on MRI may contribute to a correct preoperative diagnosis of CN.