title: Optimization of thoracic spiral CT: effects of iodinated contrast medium concentration.
abstract: OBJECTIVE
  To determine the effect of varying iodine concentration on arterial enhancement and perivenous artifact during thoracic spiral computed tomographic (CT) scanning.
  
  
  METHODS
  One hundred thirty-eight outpatients received 15.0 g (n = 76) or 22.5 g (n = 62) of iodine (300 mg/mL iodine) while undergoing thoracic spiral CT. Patients received either undiluted contrast medium, 1:1 normal saline dilution, or 3:1 normal saline dilution. Contrast medium was injected at a flow rate determined to deliver the entire iodine dose within 40 seconds. Attenuation was measured within arteries and veins. Three blinded thoracic radiologists independently graded perivenous artifact and arterial enhancement.
  
  
  RESULTS
  Perivenous artifacts were statistically significantly reduced with successive iodine dilution (P < .002). Arterial enhancement was statistically significantly better with 15.0 g of iodine diluted 1:1 when compared with the same iodine dose undiluted or diluted 3:1 (P < .01). Arterial enhancement achieved with 15.0 g of iodine diluted 1:1 was not statistically significantly lower than that achieved with 22.5 g of iodine diluted 1:1 (P > .31); however, venous artifact was greater with 22.5 g of iodine (P < .004).
  
  
  CONCLUSIONS
  Reduced iodine concentration appears to diminish perivenous artifact and to result in improved arterial enhancement during thoracic spiral CT.
authors.affiliation: Department of Radiology, Stanford University School of Medicine, CA 94305-5105, USA.
authors.forename: G D
authors.initials: GD
authors.lastname: Rubin
authors.forename: M J
authors.initials: MJ
authors.lastname: Lane
authors.forename: D A
authors.initials: DA
authors.lastname: Bloch
authors.forename: A N
authors.initials: AN
authors.lastname: Leung
authors.forename: P
authors.initials: P
authors.lastname: Stark
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016477:Artifacts; D003287:Contrast Media / Q000008:administration & dosage*; D006801:Humans; D007455:Iodine / Q000008:administration & dosage*; D007479:Iopamidol / Q000008:administration & dosage; D008875:Middle Aged; D013902:Radiography, Thoracic / Q000379:methods*; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media; D007455:Iodine; D007479:Iopamidol