title: Uniform vascular enhancement of lower-extremity artery on CT angiography using test-injection monitoring at the central level of the scan range: a simulation flow phantom study with clinical correlation.
abstract: OBJECTIVE
  To evaluate the efficacy of variable contrast injection durations and scanning delay determined by test injection analysis of computed tomography angiography (CTA) of peripheral arteries.
  
  
  METHODS
  We used a flow phantom that simulates the hemodynamics in a lower extremity artery. We set the flow rate at the pump to 2.0 or 5.0 L/minute. In protocol 1, we adopted a variable contrast injection duration based on the peak enhancement time of the test injection monitoring at the central level of the scan range. In protocol 2, we adopted a fixed contrast injection duration. The scanning delay was determined with a conventional bolus-tracking technique monitoring at the top of the scan range. Mean arterial attenuation and difference between the maximum and minimum attenuation values were calculated. To verify the phantom study results, clinical study, including 16 patients was performed under protocol 1.
  
  
  RESULTS
  The mean attenuation values under protocols 1 and 2 were comparable (563.6 Hounsfield units [HU] and 535.0 HU, respectively) at a pump flow rate of 2.0 L/minute; at 5.0 L/minute, they were 289.4 HU and 328.8 HU. The difference between the maximum and minimum attenuation values was smaller under protocol 1 than protocol 2 (76.8 HU vs. 184.9 HU) at a pump flow of 2.0 L/minute and also smaller under protocol 1 than protocol 2 (79.7 HU vs. 203.8 HU) at 5.0 L/minute. In clinical study, the mean attenuation value was 332.6 +/- 51.9 HU, and the difference between the maximum and minimum attenuation values was 55.1 +/- 24.4 HU.
  
  
  CONCLUSIONS
  The object-specific injection duration based on test injection at the central level of the scan range provides sufficient and constant vascular enhancement at CTA.
authors.affiliation: Central Radiology, Kumamoto University, Kumamoto-shi, Kumamoto, 860-8556, Japan.
authors.forename: Kie
authors.initials: K
authors.lastname: Shimizu
authors.forename: Daisuke
authors.initials: D
authors.lastname: Utsunomiya
authors.forename: Takeshi
authors.initials: T
authors.lastname: Nakaura
authors.forename: Kazuo
authors.initials: K
authors.lastname: Awai
authors.forename: Seitaro
authors.initials: S
authors.lastname: Oda
authors.forename: Yumi
authors.initials: Y
authors.lastname: Yanaga
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Funama
authors.forename: Toshinori
authors.initials: T
authors.lastname: Hirai
authors.forename: Masahiro
authors.initials: M
authors.lastname: Hashida
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Yamashita
mesh_terms: D000792:Angiography / Q000379:methods*; D003287:Contrast Media / Q000008:administration & dosage; D006801:Humans; D007479:Iopamidol / Q000008:administration & dosage*; D035002:Lower Extremity / Q000098:blood supply* / Q000000981:diagnostic imaging*; D008954:Models, Biological; D058729:Peripheral Arterial Disease / Q000000981:diagnostic imaging; D019047:Phantoms, 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; D007479:Iopamidol