title: Prospectively ECG gated CT pulmonary angiography versus helical ungated CT pulmonary angiography: impact on cardiac related motion artifacts and patient radiation dose.
abstract: OBJECTIVE
  To compare prospectively ECG gated CT pulmonary angiography (CTPA) with routine helical ungated CTPA for cardiac related motion artifacts and patient radiation dose.
  
  
  METHODS
  Twenty patients with signs and symptoms suspicious for pulmonary embolism and who had a heart rate below 85 were scanned with prospectively ECG gated CTPA. These gated exams were matched for several clinical parameters to exams from twenty similar clinical patients scanned with routine ungated helical CTPA. Three blinded independent reviewers subjectively evaluated all exams for overall pulmonary artery enhancement and for several cardiac motion related artifacts, including vessel blurring, intravascular shading, and double line. Reviewers also measured pulmonary artery intravascular density and image noise. Patient radiation dose for each technique was compared. Fourteen clinical prospectively ECG gated CTPA exams from a second institution were evaluated for the same parameters.
  
  
  RESULTS
  Prospectively ECG gated CTPA resulted in significantly decreased motion-related image artifact scores in lung segments adjacent to the heart compared to ungated CTPA. Measured image noise was not significantly different between the two types of CTPA exams. Effective dose was 28% less for prospectively ECG gated CTPA (4.9 mSv versus 6.8 mSv, p=0.02). Similar results were found in the prospectively ECG gated exams from the second institution.
  
  
  CONCLUSIONS
  Compared to routine helical ungated CTPA, prospectively ECG gated CTPA may result in less cardiac related motion artifact in lung segments adjacent to the heart and significantly less patient radiation dose.
authors.affiliation: Department of Radiology, 1959 NE Pacific Street, Box 357115, Seattle, WA 98195, United States. wshuman@u.washington.edu
authors.forename: William P
authors.initials: WP
authors.lastname: Shuman
authors.forename: Jonathon A
authors.initials: JA
authors.lastname: Leipsic
authors.forename: Janet M
authors.initials: JM
authors.lastname: Busey
authors.forename: Douglas E
authors.initials: DE
authors.lastname: Green
authors.forename: Sudhakar N
authors.initials: SN
authors.lastname: Pipavath
authors.forename: Cameron J
authors.initials: CJ
authors.lastname: Hague
authors.forename: Kent M
authors.initials: KM
authors.lastname: Koprowicz
mesh_terms: D016477:Artifacts; D001822:Body Burden; D001955:British Columbia; D055424:Cardiac-Gated Imaging Techniques / Q000379:methods*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009038:Motion; D011651:Pulmonary Artery / Q000000981:diagnostic imaging*; D011655:Pulmonary Embolism / Q000000981:diagnostic imaging*; D011829:Radiation Dosage; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D036542:Tomography, Spiral Computed / Q000379:methods*; D014481:United States