Magnetic resonance imaging characteristics of choroid plexus papilloma in the fourth ventricle.

The computed tomography (CT) and magnetic resonance (MR) imaging characteristics of two cases of small choroid plexus papilloma within the fourth ventricle are reported. CT showed the tumors as high density areas with postcontrast enhancement. MR imaging showed the tumors as basically isointense areas with marked enhancement by gadolinium-diethylenetriaminepenta-acetic acid. Important MR imaging findings included clear evidence of tumor attachment to the normal choroid plexus, location in the lower part of the fourth ventricle, and separation from the fourth ventricular floor.