ABSTRACT
Background: As the humans age, there is decrease in size of brain tissue, increase in cerebrospinal fluid volumeand enlargement of ventricles. Brain ventricles can be studied by taking linear, planimetric or volumetricmeasurements. Linear ratios of width of ventricles to the width of skull or brain are considered to be an easy andreproducible measurement for assessment of ventricles. Evans’ index is one such linear ratio; it is the ratio ofmaximum width of frontal horns and maximum transverse internal diameter of skull in the same plane.Purpose of study: The purpose of our study was to obtain a baseline data of reference values of Evans index, inhealthy north Indian population.Materials and Methods: This study was jointly conducted by Department of Anatomy and Department ofRadiodiagnosis, King George’s Medical University, U.P, Lucknow. Axial CT scans of head region reportedradiologically normal, belonging to 100 individuals of different age groups were retrospectively collected andthoroughly analyzed using Radiant DICOM Viewer Software. Study subjects were categorized into V groups as perage: 18-30years, 31-40years, 41-50years, 51-60years and above 60years. Evans’ index was calculated.Results: Among study subjects, Evans’index ranged from 0.167 to 0.29 with a mean value of 0.23±0.02. Nosignificant association was observed between age and mean Evans’ Index (p>0.05). Mean Evans’ index was equalfor male and female and was not found to change with age.Conclusion: Study provided values for normal range of Evans’ index and proposes age dependent values of thesame for healthy adult males and females. The data could be utilized in routine radiological practice and byothers where required