title: Measurement of cardiac output from dynamic pulmonary circulation time CT.
abstract: OBJECTIVE
  To introduce a method of estimating cardiac output from the dynamic pulmonary circulation time CT that is primarily used to determine the optimal time window of CT pulmonary angiography (CTPA).
  
  
  METHODS
  Dynamic pulmonary circulation time CT series, acquired for eight patients, were retrospectively analyzed. The dynamic CT series was acquired, prior to the main CTPA, in cine mode (1 frame/s) for a single slice at the level of the main pulmonary artery covering the cross sections of ascending aorta (AA) and descending aorta (DA) during the infusion of iodinated contrast. The time series of contrast changes obtained for DA, which is the downstream of AA, was assumed to be related to the time series for AA by the convolution with a delay function. The delay time constant in the delay function, representing the average time interval between the cross sections of AA and DA, was determined by least square error fitting between the convoluted AA time series and the DA time series. The cardiac output was then calculated by dividing the volume of the aortic arch between the cross sections of AA and DA (estimated from the single slice CT image) by the average time interval, and multiplying the result by a correction factor.
  
  
  RESULTS
  The mean cardiac output value for the six patients was 5.11 (l/min) (with a standard deviation of 1.57 l/min), which is in good agreement with the literature value; the data for the other two patients were too noisy for processing.
  
  
  CONCLUSIONS
  The dynamic single-slice pulmonary circulation time CT series also can be used to estimate cardiac output.
authors.affiliation: Department of Radiation Oncology, Beaumont Health System, Royal Oak, Michigan 48073.
authors.forename: Seonghwan
authors.initials: S
authors.lastname: Yee
authors.affiliation: Department of Radiology, SUNY Upstate Medical University, Syracuse, New York 13210.
authors.forename: Ernest M
authors.initials: EM
authors.lastname: Scalzetti
mesh_terms: D000328:Adult; D000368:Aged; D000792:Angiography / Q000379:methods; D001027:Aortography / Q000379:methods; D016477:Artifacts; D001794:Blood Pressure; D002302:Cardiac Output; D006339:Heart Rate; D006801:Humans; D016018:Least-Squares Analysis; D008297:Male; D008875:Middle Aged; D009929:Organ Size; D011651:Pulmonary Artery / Q000000981:diagnostic imaging; D011652:Pulmonary Circulation; D012189:Retrospective Studies; D012815:Signal Processing, Computer-Assisted; D013997:Time Factors; D014057:Tomography, X-Ray Computed / Q000379:methods*