Dolichocephaly (i.e., a long, thin head) is present on this sonogram, and can only be revealed by determining the cephalic index.
在图中所见的长头(头特别长、扁),只能用头指数来定量诊断。
英语百科
Cephalic index
The cephalic index or cranial index is the ratio of the maximum width of the head of an organism (human or animal) multiplied by 100 divided by its maximum length (i.e., in the horizontal plane, or front to back). The index is also used to categorize animals, especially dogs and cats.