title: An optimised patient-specific approach to administration of contrast agent for CT pulmonary angiography.
abstract: OBJECTIVE
  To investigate pulmonary vasculature opacification during CTPA using an optimised patient-specific protocol for administering contrast agent.
  
  
  METHODS
  CTPA was performed on 200 patients with suspected PE. Patients were assigned to two protocol groups: protocol A, fixed 80 ml contrast agent; protocol B used a patient-specific approach. The mean cross-sectional opacification profile of 8 central and 11 peripheral pulmonary arteries and veins was measured and the arteriovenous contrast ratio (AVCR) calculated. Protocols were compared using Mann-Whitney U non-parametric statistics. Jack-knife alternative free-response receiver-operating characteristic (JAFROC) analyses assessed diagnostic efficacy. Interobserver variations were investigated using kappa methods.
  
  
  RESULTS
  A number of pulmonary arteries demonstrated increases in opacification (P < 0.03) for protocol B compared to A, whilst opacification in the heart and veins was reduced in protocol B (P = 0.05). Increased AVCR in protocol B compared with A was observed at all anatomic locations (P < 0.0002). Increased JAFROC (P < 0.0002) and kappa variation were observed with protocol B (κ = 0.78) compared to A (κ = 0.25). Mean contrast volume was reduced in protocol B (33 ± 9 ml) compared to A (80 ± 1 ml).
  
  
  CONCLUSIONS
  Significant improvements in visualisation of the pulmonary vasculature can be achieved with a low volume of contrast agent using injection timing based on a patient-specific contrast formula.
  
  
  CONCLUSIONS
  • Optimal opacification of the pulmonary arteries is essential for CT pulmonary angiography. • Matching timing with vessel dynamics significantly improves vessel opacification. • This leads to increased arterial opacification and reduced venous opacification. • This can also lead to a reduced volume of contrast agent.
authors.affiliation: Department of Radiology, Royal Prince Alfred Hospital, Missenden Rd, Camperdown, 2050, Sydney, NSW, Australia, info@mdct.com.au.
authors.forename: Charbel
authors.initials: C
authors.lastname: Saade
authors.forename: Roger
authors.initials: R
authors.lastname: Bourne
authors.forename: Fadi
authors.initials: F
authors.lastname: El-Merhi
authors.forename: Arjuna
authors.initials: A
authors.lastname: Somanathan
authors.forename: Dev
authors.initials: D
authors.lastname: Chakraborty
authors.forename: Patrick
authors.initials: P
authors.lastname: Brennan
mesh_terms: D000792:Angiography / Q000379:methods*; D003287:Contrast Media / Q000008:administration & dosage*; D005260:Female; D006801:Humans; D007267:Injections; D008297:Male; D008875:Middle Aged; D011651:Pulmonary Artery / Q000000981:diagnostic imaging*; D011655:Pulmonary Embolism / Q000000981:diagnostic imaging*; D011667:Pulmonary Veins / Q000000981:diagnostic imaging*; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media