title: Effect of contrast injection protocols with dose adjusted to the estimated lean patient body weight on aortic enhancement at CT angiography.
abstract: OBJECTIVE
  The objective of our study was to investigate the effect on aortic enhancement of iodine doses adjusted for the patient estimated lean body weight (LBW) at CT angiography (CTA).
  
  
  METHODS
  CTA for the whole aorta using a 64-MDCT scanner was performed in 97 patients (mean age, 67.4 years) with confirmed or suspected aortoiliac disease. The patients were divided into two groups: a total body weight (TBW) group (n = 49) and an estimated LBW group (n = 48). LBW was estimated from the patient weight (TBW) and height. The TBW and estimated LBW groups received 360 mg I/kg of TBW and 450 mg I/kg of estimated LBW of contrast medium, respectively. The relative dose ratio for the estimated LBW group versus the TBW group was based on the fact that the standard percentage of body fat in Japanese adults with an average TBW of 60 kg is 20% (360 = 0.8 x 450). Differences in the degree of aortic enhancement and interpatient variability in aortic enhancement between the estimated LBW and TBW group were evaluated.
  
  
  RESULTS
  Mean aortic enhancement was 308.9 HU for the estimated LBW group and 314.1 HU for the TBW group, indicating no significant difference in the degree of enhancement (Welch's t test, p = 0.61). The interquartile range was smaller for the LBW group than the TBW group (52.8 vs 79.1 HU, respectively); interpatient variability was lower in the estimated LBW group. The aortic attenuation gradient in the TBW group and estimated LBW group was 20.7 and 25.8 HU, respectively; the difference was not statistically significant.
  
  
  CONCLUSIONS
  The CTA protocol using an estimated LBW-tailored dose yielded more consistent aortic enhancement with reduced interpatient variability than the CTA protocol using a TBW-based dose.
authors.affiliation: Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University, 1-1-1 Honjo, Kumamoto 860-8556, Japan.
authors.forename: Yumi
authors.initials: Y
authors.lastname: Yanaga
authors.forename: Kazuo
authors.initials: K
authors.lastname: Awai
authors.forename: Takeshi
authors.initials: T
authors.lastname: Nakaura
authors.forename: Seitaro
authors.initials: S
authors.lastname: Oda
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Funama
authors.forename: Kyongtae T
authors.initials: KT
authors.lastname: Bae
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Yamashita
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000792:Angiography / Q000379:methods*; D001018:Aortic Diseases / Q000000981:diagnostic imaging*; D001835:Body Weight; D003287:Contrast Media / Q000008:administration & dosage*; D005260:Female; D006801:Humans; D007267:Injections; D007472:Iohexol / Q000008:administration & dosage*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D018709:Statistics, Nonparametric; D014057:Tomography, X-Ray Computed
chemical_list: D003287:Contrast Media; D007472:Iohexol