Frontal and occipital horn ratio: A linear estimate of ventricular size for multiple imaging modalities in pediatric hydrocephalus

Objective: Measurement of ventricular size is important in pediatric patien ts with hydrocephalus, especially those who are being followed with cerebro spinal fluid (CSF) shunts. While volumetric techniques are a more accurate estimate of true Ventricular volume, they are often impracticable when mult iple modalities including ultrasound are used. Volumetric area and linear m easurements were compared to find the most reasonable measurement method. M ethods: Sixty-four computed tomography (CT), magnetic reasonance imaging (M RI), and ultrasound (US) scans from 25 children aged 0-17 years with hydroc ephalus, before and after treatment, were measured. Measurements included v entricular volume, a ventricular/brain ratio, and four standard linear meas ures (Evans' ratio, Huckman's measurement, minimal lateral ventricular widt h, and lateral ventricular span at the body). We also included a new ratio, which accounts for often disproportionate occipital horn expansion in pedi atric patients, called the frontal and occipital horn ratio. Volume and lin ear measurements were compared using the Spearman's correlation coefficient s and correlations were further differentiated using a Z test statistic. Th e frontal. and occipital horn ratio was also measured on CT, MRI, and US sc ans from 44 normal children aged 0-17 years to identify normal values. The effect of age was determined by linear regression. Results: The best linear correlation with ventricular size was the frontal + occipital horn ratio ( r = 0.852) and was equivalent to the ventricular/brain ratio (r = 0.891), p reviously shown to have the highest correlation with ventricular volume. Ev ans' ratio correlates less well (r = 0.423). The normal frontal and occipit al horn ratio is 0.37 and is independent of age. Conclusions: The frontal a nd occipital horn ratio is a simple method of evaluating ventricular size i n pediatric hydrocephalus patients with CSF shunts.