Figure 1 .

Coronal scan of an infant at 33 weeks of gestational age. The subarachnoid space is measured in perpendicular fashion, with electronic calipers, from the edge of the triangular sagittal sinus to the surface of the cortex. The right subarachnoid space is 0.17 cm, and the left is 0.21 cm, resulting in a mean measurement of 1.9 mm. Note that the skin line of the scalp is evident (arrow), indicating that there is no effective pressure from the transducer.