ABSTRACT
Ventriculomegaly refers to enlargement of the cerebral ventricles without specifying a cause. It is diagnosed on prenatal sonograms when the lateral ventricles measure 10 mm or greater on a transverse image at the level of the glomus of the choroid plexus (19). This measurement can be obtained on MR images in a manner similar to that with ultrasound. Ventriculomegaly can be graded into mild (10-15 mm), moderate (>15 mm with > 3 mm of adjacent cortical thickness), and severe (ventriculomegaly with < 2 mm of adjacent cortical thickness) categories (4). Ventricular measurements with fetal MR imaging corre late well with those obtained sonographically (4). Hydro cephalus is the term that indicates increased ventricular or subarachnoid space volume due to abnormal cerebro spinal fluid (CSF) dynamics (i.e., CSF overproduction, CSF underabsorption, or CSF pathway obstruction). This term is not ordinarily used unless a causal abnormality is specifically identified.
