1. Department of Medicine, Respiratory Division, Vancouver General Hospital, V5Z 1M9, and The University of British Columbia, V6T 1Z4, Canada
2. Department of Pathology, Vancouver General Hospital, V5Z 1M9, and The University of British Columbia, V6T 1Z4, Canada
3. Department of Radiology, Vancouver General Hospital, V5Z 1M9, and The University of British Columbia, V6T 1Z4, Canada