Through the American Registry for Diagnostic Medical Sonography (ARDMS), sonographers can also pursue certification, such as the registered diagnostic medical sonographer (RDMS), registered diagnostic cardiac sonographer (RDCS), registered vascular technologist (RVT) or registered in musculoskeletal (RMSK).nly a few states require sonographers to be licensed. While state requirements can vary, a professional certification from a national credentialing organization is often required to become licensed.