title: Attenuation characteristics and application of gadolinium-DTPA in fast helical computed tomography.
abstract: OBJECTIVE
  The computed tomography (CT) attenuation characteristics of gadolinium (Gd)-DTPA have been analyzed both in vitro and in vivo to evaluate the possibility of its substitution for iodine in patients with contraindications for iodine utilization.
  
  
  METHODS
  In vitro attenuation values of Gd-DTPA were measured relative to those of iodine under variation of concentration, voltage, preattenuation, and beam hardening. In vivo iodine attenuation values were obtained for different injection rates (3.0 mL/second and 4.5 mL/second) to calculate the attenuation values of 0.5 molar Gd-DTPA to be expected in vivo by the help of the previously obtained attenuation-concentration curves. Subsequently, CT enhancement after an injection of 0.3 mmol/kg body weight Gd-DTPA was evaluated in five patients with contraindications for iodine administration.
  
  
  RESULTS
  The injection of a 0.7 molar Gd-DTPA solution at a flow rate of 4.5 mL/second was calculated to be equivalent to that of 2.36 molar iodine at a flow rate of 3 mL/ second. Sufficient enhancement for diagnosis of dissections/ aneurysms of arterial vessels could be achieved. Both arterial and venous cervical or thoracic vessels could be enhanced to 100 Hounsfield units with a bolus injection. In contrast to the thyroid gland, the parenchyma of the liver and the kidney was not sufficiently enhanced.
  
  
  CONCLUSIONS
  Gadolinium-DTPA is more effective than iodine in x-ray attenuation; however, its present concentration of 0.5 molar and permitted dose of 0.3 mmol/kg body weight are insufficient to provide parenchymal enhancement with CT. The visualization of arterial vessels appears possible with gadolinium enhanced CT but requires optimal timing and fast scanning capabilities.
authors.affiliation: Department of Radiology, University Hospital Grosshadern, Munich, Germany.
authors.forename: W
authors.initials: W
authors.lastname: Luboldt
authors.forename: M
authors.initials: M
authors.lastname: De Santis
authors.forename: A
authors.initials: A
authors.lastname: von Smekal
authors.forename: M
authors.initials: M
authors.lastname: Reiser
mesh_terms: D000784:Aortic Dissection / Q000000981:diagnostic imaging; D000792:Angiography / Q000379:methods*; D003287:Contrast Media / Q000008:administration & dosage*; D004305:Dose-Response Relationship, Drug; D019786:Gadolinium DTPA / Q000008:administration & dosage; D006801:Humans; D007275:Injections, Intravenous; D007668:Kidney / Q000098:blood supply / Q000000981:diagnostic imaging; D008099:Liver / Q000098:blood supply / Q000000981:diagnostic imaging; D019047:Phantoms, Imaging; D011237:Predictive Value of Tests; D011856:Radiographic Image Enhancement / Q000379:methods*; D013154:Spleen / Q000098:blood supply / Q000000981:diagnostic imaging; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA