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Frontal and occipital horn ratio: A linear estimate of ventricular size for multiple imaging modalities in pediatric
B B O'Hayon1, J M Drake, M G Ossip
1Division of Neurosurgery, Hospital for Sick Children, Toronto, Ont., Canada.
Insights
A new frontal and occipital horn ratio effectively measures ventricular size in pediatric hydrocephalus patients with cerebrospinal fluid (CSF) shunts, offering a simpler alternative to volumetric methods.
Area of Science:
- Pediatric Neurology
- Neuroradiology
- Medical Imaging
Background:
- Accurate ventricular size measurement is crucial for managing pediatric hydrocephalus, particularly in patients with cerebrospinal fluid (CSF) shunts.
- Volumetric methods provide precise ventricular volume but are often impractical with diverse imaging modalities like ultrasound.
- Linear and area-based measurements are commonly used but may not fully capture complex ventricular changes.
Purpose of the Study:
- To compare linear and volumetric measurements for assessing ventricular size in pediatric hydrocephalus.
- To evaluate the efficacy of a novel frontal and occipital horn ratio against established methods.
- To determine the most practical and reliable measurement for clinical use.
Main Methods:
- Analyzed 64 CT, MRI, and ultrasound scans from 25 pediatric hydrocephalus patients (0-17 years) before and after treatment.
- Measured ventricular volume, ventricular/brain ratio, and four standard linear measures (Evans' ratio, Huckman's measurement, minimal lateral ventricular width, lateral ventricular span).
- Introduced and assessed the frontal and occipital horn ratio, comparing it with other metrics using Spearman's correlation and Z tests; normal values were established in 44 controls.
Main Results:
- The frontal and occipital horn ratio demonstrated the strongest linear correlation with ventricular size (r = 0.852), comparable to the ventricular/brain ratio (r = 0.891).
- Established linear measures like Evans' ratio showed weaker correlations (r = 0.423).
- The normal frontal and occipital horn ratio was determined to be 0.37, independent of age.
Conclusions:
- The frontal and occipital horn ratio offers a simple and effective method for evaluating ventricular size in pediatric hydrocephalus.
- This ratio provides a reliable alternative to more complex volumetric measurements in clinical practice.
- Its independence from age simplifies its application across pediatric age groups.
Objective:
Measurement of ventricular size is important in pediatric patients with hydrocephalus, especially those who are being followed with cerebrospinal fluid (CSF) shunts. While volumetric techniques are a more accurate estimate of true ventricular volume, they are often impracticable when multiple modalities including ultrasound are used. Volumetric area and linear measurements were compared to find the most reasonable measurement method.
Methods:
Sixty-four computed tomography (CT), magnetic resonance imaging (MRI), and ultrasound (US) scans from 25 children aged 0-17 years with hydrocephalus, before and after treatment, were measured. Measurements included ventricular volume, a ventricular/brain ratio, and four standard linear measures (Evans' ratio, Huckman's measurement, minimal lateral ventricular width, and lateral ventricular span at the body). We also included a new ratio, which accounts for often disproportionate occipital horn expansion in pediatric patients, called the frontal and occipital horn ratio. Volume and linear measurements were compared using the Spearman's correlation coefficients and correlations were further differentiated using a Z test statistic. The frontal and occipital horn ratio was also measured on CT, MRI, and US scans 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), previously shown to have the highest correlation with ventricular volume. Evans' ratio correlates less well (r = 0.423). The normal frontal and occipital horn ratio is 0.37 and is independent of age.
Conclusions:
The frontal and occipital horn ratio is a simple method of evaluating ventricular size in pediatric hydrocephalus patients with CSF shunts.