[1] UNIV WASHINGTON, DEPT NEUROL, SEATTLE, WA 98195 USA
[2] UNIV WASHINGTON, DEPT EPIDEMIOL, SEATTLE, WA 98195 USA
[3] UNIV WASHINGTON, DEPT BIOSTAT, SEATTLE, WA 98195 USA
[4] NHLBI, DIV EPIDEMIOL & CLIN APPLICAT, BETHESDA, MD 20892 USA
[5] WAKE FOREST UNIV, BOWMAN GRAY SCH MED, DEPT PUBL HLTH SCI, WINSTON SALEM, NC 27103 USA
[6] JOHNS HOPKINS UNIV, SCH MED, DEPT RADIOL, NEURORADIOL DIV, BALTIMORE, MD 21205 USA
[7] JOHNS HOPKINS UNIV, SCH MED, DEPT MED, BALTIMORE, MD 21205 USA
[8] UNIV PITTSBURGH, MED CTR, DEPT RADIOL & NEUROL SURG, PITTSBURGH, PA USA
[9] UNIV ARIZONA, CTR RESP SCI, TUCSON, AZ USA
[10] TUFTS UNIV NEW ENGLAND MED CTR, DEPT RADIOL, BOSTON, MA 02111 USA