title: Optimisation of contrast medium volume and injection-related factors in CT pulmonary angiography: 64-slice CT study.
abstract: OBJECTIVE
  To compare the image quality of computed tomography pulmonary angiography (CTPA) obtained with the injection of various low doses of contrast medium (CM) with different injection-related factors.
  
  
  METHODS
  A total of 90 patients (42 females, 48 males; 54.3 +/- 18.6 years) undergoing CTPA were included. Three CM protocols, each containing 30 patients, were created. Protocols 1, 2 and 3 consisted of a CM of 60 ml, 55 ml and 50 ml, and a bolus trigger level of 120 HU, 90 HU and 75 HU, respectively. Injection was uniphasic for protocols 1 and 2 (flow rate 5 ml/s), and biphasic for protocol 3 (flow rates 5 and 4 ml/s); with saline flushing afterwards. Enhancement was measured in three central and six peripheral pulmonary arteries.
  
  
  RESULTS
  The mean attenuation value for pulmonary arteries was over 250 HU for all protocols. There was no difference between the attenuation levels with the protocols (p > 0.05). The percentage of pulmonary arteries exceeding optimal attenuation (> or =250 HU) showed that protocols 2 and 3 were 90-100% successful (p < 0.05).
  
  
  CONCLUSIONS
  The use of proper injection-related factors during CTPA, such as a low trigger level and a high flow rate with saline injection following a decreased CM volume (55 ml or 50 ml), will enable adequate pulmonary artery contrast enhancement.
authors.affiliation: Department of Radiology, Ankara Training and Research Hospital, Ankara, Turkey. uysalselma@yahoo.com
authors.forename: Selma Uysal
authors.initials: SU
authors.lastname: Ramadan
authors.forename: Pinar
authors.initials: P
authors.lastname: Kosar
authors.forename: Iclal
authors.initials: I
authors.lastname: Sonmez
authors.forename: Sevilay
authors.initials: S
authors.lastname: Karahan
authors.forename: Ugur
authors.initials: U
authors.lastname: Kosar
mesh_terms: D000792:Angiography / Q000187:drug effects / Q000379:methods*; D003287:Contrast Media / Q000008:administration & dosage; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D007455:Iodine / Q000008:administration & dosage*; D008297:Male; D008875:Middle Aged; D011651:Pulmonary Artery / Q000000981:diagnostic imaging*; D011655:Pulmonary Embolism / Q000000981:diagnostic imaging*; D011856:Radiographic Image Enhancement / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media; D007455:Iodine