So on a CT scan, subdural hematomas follow the contour of the brain and form a crescent shape and cross suture lines.

所以CT上，硬膜下轮廓和大脑轮廓一致，呈新月形，过缝。

Since the outer layer of the dura mater adheres tightly to the skull at sutures, epidural hematoma don't cross suture lines, and they push on the brain, forming a bi-convex shape.

由于硬脑膜外层与缝处紧紧相贴，硬膜外出不会过缝，且会压迫大脑，形成双凸镜形。

Subdural hematomas cross suture lines and follow the contour of the brain forming a crescent shape, unlike epidural hematomas which don't cross suture lines and push on the brain and form a bi-convex shape.

硬膜下可过缝，与大脑轮廓一致，呈新月形；相形之下，硬膜外不过缝，而且压迫大脑呈双凸镜形。