1 Department of Respiratory and Critical Care Medicine, National Cancer Centre, Singapore General Hospital, Singapore. Electronic address: chinnjing@pacific.net.sg.
2 Department of Respiratory and Critical Care Medicine, National Cancer Centre, Singapore General Hospital, Singapore.
3 Department of Diagnostic and Therapeutic Radiology, National Cancer Centre, Singapore General Hospital, Singapore.
4 Department of Oncology, National Cancer Centre, Singapore General Hospital, Singapore.