title: Using a saline chaser to decrease contrast media in abdominal CT.
abstract: OBJECTIVE
  The purpose of this study was to compare hepatic tumor conspicuity on CT after injection of either 150 mL of contrast material or 100 mL of contrast material plus a 50-mL saline chaser.
  
  
  METHODS
  We evaluated 86 hypoattenuating liver metastases in 26 patients. Patients underwent CT in two sessions separated by a mean of 85 days: one time with 150 mL of contrast material and the other time with 100 mL of contrast material followed by a 50-mL saline chaser. The order of the sessions was randomized. Contrast material was administered via power injector and matched for injection rate and delay time. Attenuation values were obtained from normal liver tissue and metastases and from the spleen, kidney, aorta, and inferior vena cava.
  
  
  RESULTS
  The 150 mL dose of contrast material caused slightly greater liver and tumor attenuation than 100 mL of contrast material with a chaser (mean hepatic attenuation, 95.6 vs 89.8 H, respectively; p < 0.03, paired t test; mean tumor attenuation, 53.2 vs 49.1 H, respectively; r = 0.71, p = 0.09). The difference in conspicuity of liver lesions was slightly greater with 150 mL than with 100 mL with a chaser (46.8 H vs 44.2 H; r = 0.46, p = 0.08, paired t test), but was of doubtful clinical significance (2.6 H). Kidney, spleen, and vascular structures enhanced more with 150 mL than with 100 mL and a chaser.
  
  
  CONCLUSIONS
  Using 100 mL of contrast material and a saline chaser did not result in a meaningful difference in liver parenchyma attenuation or lesion conspicuity compared with using 150 mL of contrast medium alone. Routine use of a chaser for abdominal CT may yield cost savings and a decreased risk of contrast nephropathy.
authors.affiliation: Department of Radiology, University of Wisconsin Hospital & Clinics, 600 Highland Ave., Madison, WI 53792-3252, USA.
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Dorio
authors.forename: Fred T
authors.initials: FT
authors.lastname: Lee
authors.forename: Kevin P
authors.initials: KP
authors.lastname: Henseler
authors.forename: Mark
authors.initials: M
authors.lastname: Pilot
authors.forename: Myron A
authors.initials: MA
authors.lastname: Pozniak
authors.forename: Thomas C
authors.initials: TC
authors.lastname: Winter
authors.forename: Sarah A
authors.initials: SA
authors.lastname: Shock
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003287:Contrast Media / Q000008:administration & dosage* / Q000009:adverse effects / Q000191:economics; D017046:Cost Savings; D005260:Female; D006801:Humans; D007472:Iohexol / Q000009:adverse effects / Q000191:economics; D007674:Kidney Diseases / Q000139:chemically induced / Q000517:prevention & control; D008113:Liver Neoplasms / Q000000981:diagnostic imaging* / Q000556:secondary*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011856:Radiographic Image Enhancement / Q000191:economics / Q000379:methods; D012680:Sensitivity and Specificity; D012965:Sodium Chloride / Q000008:administration & dosage; D036542:Tomography, Spiral Computed / Q000191:economics / Q000379:methods*
chemical_list: D003287:Contrast Media; D007472:Iohexol; D012965:Sodium Chloride