title: First-pass CT perfusion in small peripheral lung cancers: effect of the temporal interval between scan acquisitions on the radiation dose and quantitative vascular parameters.
abstract: OBJECTIVE
  To evaluate the effect of the temporal interval (TI) between scan acquisitions on the radiation dose and vascular parameters of computed tomography perfusion (CTP) in small peripheral lung cancers.
  
  
  METHODS
  With 7 excluded, 40 patients with peripheral lung cancer (diameter ≤4 cm) prospectively underwent a 30-second CTP study. Vascular parameters were calculated for TI datasets of 0, 1, 1.5, 2, 2.5, and 3.5 seconds. With the TI and tumor diameter as fixed effects, univariate general linear model analysis was used to compare the vascular parameters at interval datasets with the reference CTP of 0 seconds.
  
  
  RESULTS
  The TI had an impact on the blood flow and transit time (P < .001 for both) but not on the blood volume and permeability surface area. The diameter influenced four vascular parameters (P < .001 for all). Compared to the reference, no statistical differences were found in the four parameters at intervals of 0.5, 1, and 1.5 seconds (P > .05 for all). In addition, blood flow was overestimated and transit was underestimated with increasing intervals of 2, 2.5, and 3.5 seconds (P < .05 for all), but not the remaining parameters. An increased TI of 0.5-1.5 seconds resulted in an estimated radiation dose reduction of 50-73%.
  
  
  CONCLUSIONS
  The TI of 1.5 seconds between scan acquisitions in first-pass phase of CTP could be used to optimally balance the radiation dose and quantitative estimation in small peripheral lung cancers.
authors.affiliation: Department of Radiology, The Third Affiliated Hospital of Suzhou University, Changzhou, P. R. China.
authors.forename: Fei
authors.initials: F
authors.lastname: Shan
authors.forename: Wei
authors.initials: W
authors.lastname: Xing
authors.forename: Jianguo
authors.initials: J
authors.lastname: Qiu
authors.forename: Zhiyong
authors.initials: Z
authors.lastname: Zhang
authors.forename: Shan
authors.initials: S
authors.lastname: Yang
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001783:Blood Flow Velocity; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D009389:Neovascularization, Pathologic / Q000000981:diagnostic imaging* / Q000503:physiopathology; D055420:Perfusion Imaging / Q000379:methods*; D011829:Radiation Dosage; D011856:Radiographic Image Enhancement / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013997:Time Factors; D014057:Tomography, X-Ray Computed / Q000379:methods*
keywords: Lung neoplasms; X-ray computed; blood supply; diagnostic imaging; radiation dosage; tomography