ventricular-brain ratio ventricular-brain ratio ventricular-brain ratio (vbr), also known as the ventricle-to-brain ratio or ventricle-brain ratio, is the ratio of total ventricle area to total brain area, which can be calculated with planimetry from brain imagining techniques such as ct scans. it is a common measure of ventricular dilation or cerebral atrophy in patients with traumatic brain injury or hydrocephalus ex vacuo. vbr also tends to increase with age. example of enlarged lateral ventricles in schizophrenia. generally, a higher vbr means a worse prognosis for recovering from a brain injury. for example, vbr is significantly correlated with performance on the luria-nebraska neuropsychological battery. studies have found people with schizophrenia have larger third ventricles and vbr. correlational studies have found relationships between ventricle-brain ratio and binge eating and inversely with plasma thyroid hormone concentration.