title: Author reply to comments.
authors.affiliation: Department of Radiodiagnosis, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Ashu Seith
authors.initials: AS
authors.lastname: Bhalla
authors.affiliation: Department of Radiodiagnosis, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Ankur
authors.initials: A
authors.lastname: Goyal
authors.affiliation: Department of Pulmonary Medicine, All India Institute of Medical Sciences, New Delhi, India E-mail: ashubhalla1@yahoo.com.
authors.forename: Randeep
authors.initials: R
authors.lastname: Guleria
authors.affiliation: Department of Radiodiagnosis, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Arun Kumar
authors.initials: AK
authors.lastname: Gupta