[1] Johns Hopkins Univ, Sch Med, Dept Otolaryngol Head & Neck Surg, Div Head & Neck Endocrine Surg, Baltimore, MD 21205 USA
[2] Johns Hopkins Univ, Sch Med, Dept Radiol & Radiol Sci, Baltimore, MD USA
[3] Johns Hopkins Bloomberg Sch Publ Hlth, Dept Epidemiol, Baltimore, MD USA