title: Role of low dose CT angiography in the follow-up after endovascular aneurysm repair of abdominal aorta.
abstract: BACKGROUND
  Computed tomography angiography (CTA) is the most employed modality in the follow-up after endovascular aneurysm repair (EVAR) of abdominal aorta (AA); repeated standard controls expose patients to a high cumulative radiation dose (RD).
  
  
  OBJECTIVE
  To compare image quality and RD between 100 kV and 120 kV protocols in the same group of patients, previously treated with EVAR.
  
  
  METHODS
  Thirty patients, who had performed a previous CTA at 120 kV, underwent a low dose CTA with the same 64-detector machine. Images were evaluated qualitatively and quantitatively. The influence of body mass index (BMI), considering three groups of patients (normal weight, overweight, and obese) was also assessed. RD values (volume CT dose index and effective dose) were calculated.
  
  
  RESULTS
  The mean qualitative score at 100 kV was worse than that at 120 kV, but the difference was not statistically significant and in all cases the image quality was satisfactory. At 100 kV the vessels mean attenuation value was significantly higher; signal-to-noise ratio significantly lower; contrast-to-noise ratio lower, but the difference was not significant. Regarding BMI, the difference in the qualitative score was significant in the obese group, but not in the other two groups; of the quantitative parameters only the signal-to-noise ratio presented a significant difference in the obese group. The average CTDIvol was reduced by 22% and the mean effective dose by 36% with the 100 kV protocol compared to the 120 kV protocol. Both differences were significant.
  
  
  CONCLUSIONS
  The 100 kV protocol allowed a consistent RD reduction, maintaining a satisfactory image quality in all patients.
authors.affiliation: Department of Radiology. University Hospital. Varese, Italy carlo.fugazzola@ospedale.varese.it.
authors.forename: Monica
authors.initials: M
authors.lastname: Macchi
authors.affiliation: Department of Radiology. University Hospital. Varese, Italy.
authors.forename: Chiara
authors.initials: C
authors.lastname: Floridi
authors.affiliation: Department of Medical Physics. University Hospital. Varese, Italy.
authors.forename: Sabina
authors.initials: S
authors.lastname: Strocchi
authors.affiliation: Department of Radiology. University Hospital. Varese, Italy.
authors.forename: Federico
authors.initials: F
authors.lastname: Fontana
authors.affiliation: Department of Radiology. University Hospital. Varese, Italy.
authors.forename: Monica
authors.initials: M
authors.lastname: Mangini
authors.affiliation: Department of Radiology. University Hospital. Varese, Italy.
authors.forename: Filippo
authors.initials: F
authors.lastname: Piacentino
authors.affiliation: Department of Radiology. University Hospital. Varese, Italy.
authors.forename: Ejona
authors.initials: E
authors.lastname: Duka
authors.affiliation: Interventional Radiology Research Center. University of Insubria, Varese, Italy.
authors.forename: Alberto V
authors.initials: AV
authors.lastname: Donati
authors.affiliation: Department of Radiology. University Hospital. Varese, Italy.
authors.forename: Carlo
authors.initials: C
authors.lastname: Fugazzola
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001012:Aorta, Abdominal / Q000000981:diagnostic imaging / Q000601:surgery; D017544:Aortic Aneurysm, Abdominal / Q000000981:diagnostic imaging* / Q000601:surgery*; D003287:Contrast Media; D057510:Endovascular Procedures; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007472:Iohexol / Q000031:analogs & derivatives; D008297:Male; D008875:Middle Aged; D011829:Radiation Dosage; D011857:Radiographic Image Interpretation, Computer-Assisted; D059629:Signal-To-Noise Ratio; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome
chemical_list: D003287:Contrast Media; C093233:iobitridol; D007472:Iohexol
keywords: Computed tomography (CT) angiography; EVAR; abdominal aorta; low dose CT; radiation dose