title: Prediction of maximum hepatic enhancement on computed tomography from dose of contrast material and patient weight: proposal of a new formula and evaluation of its accuracy.
abstract: OBJECTIVE
  To evaluate the accuracy of formulas for predicting maximum hepatic enhancement (MHE) on computed tomography (CT) from patient weight and dose of contrast material.
  
  
  METHODS
  A total of 104 patients weighing 40-80 kg (mean 58+/-9.7 kg) underwent contrast enhanced abdominal CT. Contrast material [100 ml at 300 mgI/ml (n=54) or 370 mgI/ml (n=50)] was administered at the rate of 2 ml/sec. MHE (HU) was obtained in each patient. We assumed the following exponential model: MHE = C1W(C2)D(C3) (W: body weight in kg, D: dose of iodine in gram, C1, C2, and C3: coefficients). These coefficients were obtained by a multiple regression analysis performed on the data. The accuracy of our formula was evaluated by the ratio (AR) of calculated MHE to measured MHE, and the difference (AD) between calculated MHE and measured MHE. The values of AR and AD in our formula were compared with those in Heiken's formula: MHE=CD/W (C: coefficient).
  
  
  RESULTS
  We derived MHE=13.2 D/W(0.5) as our exponential formula and MHE =101 D/W as Heiken's formula. AR was 1.04+/-0.20 (mean +/- SD) and AD was 9.03+/-6.35 with our formula, while the corresponding values were 1.04+/-0.21 and 9.55+/-6.88 with Heiken's formula. The values of AR and AD were not significantly different between the two formulas.
  
  
  CONCLUSIONS
  The combination of our formula and Heiken's formula may be useful in determining the optimal dose of contrast material according to patient weight for the detection of hypovascular liver tumors.
authors.affiliation: Department of Radiology, Teikyo University School of Medicine Tokyo, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Takeshita
mesh_terms: D001835:Body Weight; D003287:Contrast Media; D005260:Female; D006801:Humans; D007479:Iopamidol; D008099:Liver / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D013997:Time Factors; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media; D007479:Iopamidol