1. Kaiser Permanente Division of Research, Oakland, California, USA.
2. Department of Radiological Sciences, University of California Irvine School of Medicine, Irvine, California, USA.
3. Safety Measurement Institute, Korea Research Institute of Standards and Science (KRISS), Daejeon, Republic of Korea.
4. Departments of Psychiatry and Neurology and Epidemiology and Biostatistics, University of California San Francisco, San Francisco, California, USA.