Normative parameters of the Evans Index using Computer Tomography in the Saudi population.

Objectives: To calculate The Evans Index (EI) in normal Individuals. Ventricular enlargement is referred to as hydrocephalus. Computer tomography (CT) scans are commonly used to investigate such intracranial pathologies. The EI is an important parameter for diagnosing hydrocephalus.

Methods: We included all patients who underwent Computer tomography (CT) scan of the brain that was reported as normal. The mean EI was calculated for the whole sample stratified by age, gender, and ethnicity. Patients with an initial report indicating any intracranial pathology, such as hydrocephalus, tumors, hemorrhages, or neurodegenerative disorders, were excluded.

Results: A total of 1,330 brain CT scans carried out at our institution were reviewed retrospectively from August 2021 to December 2021. A total of 423 CT scans were screened after excluding 25 patients with abnormal imaging findings and 14 repeated images for the same patients. A total of 384 patients were included. The mean EI for the entire sample was 0.2550±0.0277. There was a minimal but statistically significant difference based on gender, with a mean EI of 0.2588±0.0274 for males and 0.2517±0.0276 for females (=0.012). There was no statistically significant difference between Saudi and non-Saudi patients. EI increased progressively with age in both genders.

Conclusion: Our EI values were similar to many of those reported in other countries, which supports the use of the 0.3 cutoff for the diagnosis of hydrocephalus, regardless of gender, age, or ethnicity.