An official website of the United States government
Here's how you know
Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Active surveillance (AS) – schematic depicting disease re-classification and termination of active surveillance after serial magnetic resonance imaging (MRI) monitoring. The mean interval between MRI scans was 1.9 years.