title: Effects of electrocardiogram gating on CT pulmonary angiography image quality.
abstract: BACKGROUND
  Pulmonary embolism (PE) is the third most common cause of death from cardiovascular disease. Computed-tomographic pulmonary angiography (CTPA) is an accurate and safe test for diagnosing PE. The aim of this retrospective analysis was to evaluate the effects on image quality (IQ) of electrocardiogram (ECG) gating during CTPA.
  
  
  METHODS
  Fifty consecutive patients presenting for CTPA were included in the study. A single acquisition was performed, resulting in two reconstructions: one at 75% of the R-R interval and the other without ECG influence. IQ evaluation was undertaken by two radiologists, focusing on respiratory and cardiac motion, image noise, low-contrast resolution, vessel and lung clarity, contrast media opacification and artefacts. Various regions of the lungs and vasculature were evaluated, and IQ scores were statistically compared.
  
  
  RESULTS
  For the ECG-tagged reconstructions, IQ was noted to be better overall with regard to vessel clarity (P < 0.05) and cardiac motion (P < 0.05), while lung clarity was better only in the left lower zone (P < 0.05). IQ was better with regard to image noise (P < 0.05) and low-contrast resolution (P < 0.05) in the non-ECG-tagged reconstructions. No statistical IQ difference between the two types of reconstruction was noted with regard to respiratory motion, contrast media opacification or presence of artefacts.
  
  
  CONCLUSIONS
  The two types of reconstruction provide complementary information for evaluating CTPA results.
authors.affiliation: Department of Diagnostic Imaging, Monash Medical Centre, Monash Health.
authors.forename: Nicholas D
authors.initials: ND
authors.lastname: Ardley
authors.forename: Ken K
authors.initials: KK
authors.lastname: Lau
authors.forename: Kevin
authors.initials: K
authors.lastname: Buchan
authors.forename: Eldho
authors.initials: E
authors.lastname: Paul
authors.forename: John M
authors.initials: JM
authors.lastname: Troupis
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000792:Angiography / Q000379:methods*; D055424:Cardiac-Gated Imaging Techniques / Q000379:methods*; D003287:Contrast Media / Q000008:administration & dosage; D005260:Female; D006801:Humans; D007275:Injections, Intravenous; D007472:Iohexol / Q000008:administration & dosage; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011651:Pulmonary Artery / Q000000981:diagnostic imaging*; D011655:Pulmonary Embolism / Q000000981:diagnostic imaging*; D011856:Radiographic Image Enhancement / Q000379:methods*; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media; D007472:Iohexol
keywords: ECG gating; cardiopulmonary anatomy; computed tomography; pulmonary embolism; vascular