An official website of the United States government
The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before
sharing sensitive information, make sure you’re on a federal
government site.
The site is secure.
The https:// ensures that you are connecting to the
official website and that any information you provide is encrypted
and transmitted securely.
Cheng J, Serra-Hsu F, Tian Y, Lin W, Qin YX.Cheng J, et al. Among authors: tian y.Ultrasound Med Biol. 2011 Dec;37(12):2116-25. doi: 10.1016/j.ultrasmedbio.2011.08.009. Epub 2011 Oct 26.Ultrasound Med Biol. 2011.PMID: 22033134Free PMC article.