title: SPECT-CT/VQ versus CTPA for diagnosing pulmonary embolus and other lung pathology: Pre-existing lung disease should not be a contraindication.
abstract: BACKGROUND
  Single Photon Emission Computed Tomography-Ventilation-Perfusion (SPECT-VQ) with low-dose CT (SPECT-CT/VQ) has equivalent diagnostic accuracy to CTPA for diagnosing pulmonary embolus (PE) while using lower radiation doses, but is underutilized owing to perceived inaccuracy of scintigraphy in the setting of pre-existing lung disease. This study assesses the accuracy of SPECT-CT/VQ compared with CTPA for the diagnosis of PE, including in patients with pre-existing lung disease.
  
  
  METHODS
  Retrospective non-inferiority cohort study of all patients who underwent SPECT-CT/VQ scanning at St Vincent's Hospital, NSW, from June 2012 to November 2013, who also had a CTPA within the same admission and <72 h apart (n = 102).
  
  
  RESULTS
  SPECT-CT/VQ had 100% sensitivity and 94.4% specificity when compared with CTPA. Of the 102 patients, 14 were lung transplant patients, and 27 had other pre-existing lung disease (41/102, 40.2%), with SPECT-CT/VQ having a sensitivity of 100% and specificity of 97.2% in this patient group. Non-inferiority of SPECT-CT/VQ was demonstrated at a significance level of 0.005.
  
  
  CONCLUSIONS
  SPECT-CT/VQ has high sensitivity and specificity for diagnosing PE compared with CTPA, even among patients with pre-existing lung disease, with lower radiation doses.
authors.affiliation: Department of Medical Imaging, St Vincent's Hospital, Darlinghurst, New South Wales, Australia.
authors.forename: Kartik Dev
authors.initials: KD
authors.lastname: Bhatia
authors.affiliation: Department of Medical Imaging, St Vincent's Hospital, Darlinghurst, New South Wales, Australia.
authors.forename: Chaitanya
authors.initials: C
authors.lastname: Ambati
authors.affiliation: Department of Medical Imaging, St Vincent's Hospital, Darlinghurst, New South Wales, Australia.
authors.forename: Rajiv
authors.initials: R
authors.lastname: Dhaliwal
authors.affiliation: Department of Medical Imaging, St Vincent's Hospital, Darlinghurst, New South Wales, Australia.|Department of Radiology, Royal Prince Alfred Hospital, Camperdown, New South Wales, Australia.
authors.forename: Royce
authors.initials: R
authors.lastname: Paschkewitz
authors.affiliation: Department of Medical Imaging, St Vincent's Hospital, Darlinghurst, New South Wales, Australia.
authors.forename: Eugene
authors.initials: E
authors.lastname: Hsu
authors.affiliation: Department of Medical Imaging, St Vincent's Hospital, Darlinghurst, New South Wales, Australia.
authors.forename: Bao
authors.initials: B
authors.lastname: Ho
authors.affiliation: Department of Medical Imaging, St Vincent's Hospital, Darlinghurst, New South Wales, Australia.
authors.forename: Andy
authors.initials: A
authors.lastname: Young
authors.affiliation: Department of Medical Imaging, St Vincent's Hospital, Darlinghurst, New South Wales, Australia.
authors.forename: Louise
authors.initials: L
authors.lastname: Emmett
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D000072226:Computed Tomography Angiography / Q000379:methods*; D005260:Female; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging; D008171:Lung Diseases / Q000000981:diagnostic imaging; D008297:Male; D008875:Middle Aged; D011651:Pulmonary Artery / Q000000981:diagnostic imaging; D011655:Pulmonary Embolism / Q000000981:diagnostic imaging*; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*; D055815:Young Adult
keywords: CTPA; SPECT; VQ; pulmonary embolus; radiation dose