The Bicaudate Index (BCI) can be used to evaluate a patient for lateral ventricular dilatation.

Exam: head CT in the transverse plane


Measurement taken along lines perpendicular to midline of the brain:

(1) minimum distance between the two caudate nuclei in mm

(2) internal skull diameter along the same line in mm


bicarudate index =

= (bicaudate distance) / (internal skull diameter)



• The ratio is analyzed against tables of the age-appropriate reference range (see Table 11 of Wilk et al).

• A value above the upper limit of normal for age may indicate the presence of hydrocephalus.

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