title: Analysis of contrast time-enhancement curves to optimise CT pulmonary angiography.
abstract: OBJECTIVE
  To assess enhancement profiles of the pulmonary artery (PA) and determine optimal scan timing in PA computed tomography (CT) angiography.
  
  
  METHODS
  One hundred consecutive patients referred for contrast-enhanced chest CT were prospectively studied. Fifteen low-radiation monitoring images were acquired at 2-second intervals, 5 seconds after the start of an injection of 370 mg iodine/I contrast medium for 1 ml/kg of body weight injected over 20 seconds. Contrast time-enhancement data were measured over the PA. The time and magnitude of peak as well as times to five different enhancement thresholds (50, 100, 150, 200, 250 HU) were calculated. A set of candidate fixed and circulation-adjusted scan delays were analysed and compared in terms of the quality of contrast enhancement over the 4-second diagnostic scan duration.
  
  
  RESULTS
  The mean degree of peak PA enhancements was 431.4±65.2HU (range, 263.8-575.3HU). The mean time to peak enhancement was 22.4±3.1 seconds (range, 11-27 seconds). From potential fixed delays ranging 11-27 seconds, 19 seconds showed the highest enhancement quality. For the circulation-adjusted delays, the combination of 150 HU bolus-track threshold with diagnostic delay of 10 seconds had the highest enhancement quality.
  
  
  CONCLUSIONS
  Peak enhancement of PA occurred, on average, right after completion of contrast injection for 20 seconds. The fixed scan delay of 19 seconds or circulation-adjusted delay with the bolus-threshold of 150 HU and diagnostic delay of 10 seconds appear optimal.
authors.affiliation: Department of Radiology, Suzhou Science & Technology Town Hospital, Suzhou, Jiangsu Province, China; Department of Radiology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
authors.forename: J
authors.initials: J
authors.lastname: Zhu
authors.affiliation: Department of Radiology, Huaian Tumor Hospital, Huai'an, Jiangsu Province, China.
authors.forename: Z
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Department of Radiology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Kim
authors.affiliation: Department of Radiology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
authors.forename: S K
authors.initials: SK
authors.lastname: Bae
authors.affiliation: Department of Radiology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
authors.forename: C
authors.initials: C
authors.lastname: Tao
authors.affiliation: Department of Radiology, The Second Affiliated Hospital of Soochow University, Suzhou, Jiangsu Province, China.
authors.forename: J
authors.initials: J
authors.lastname: Gong
authors.affiliation: Department of Radiology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA. Electronic address: baek@upmc.edu.
authors.forename: K T
authors.initials: KT
authors.lastname: Bae
mesh_terms: D000328:Adult; D000368:Aged; D000072226:Computed Tomography Angiography / Q000379:methods*; D003287:Contrast Media / Q000493:pharmacokinetics*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011651:Pulmonary Artery / Q000000981:diagnostic imaging*; D011856:Radiographic Image Enhancement / Q000379:methods*; D013997:Time Factors; D055815:Young Adult
chemical_list: D003287:Contrast Media