title: Size of colorectal liver metastases at abdominal CT: comparison of precontrast and postcontrast studies.
abstract: OBJECTIVE
  To investigate whether measurements of hepatic metastases from colorectal carcinoma before contrast material administration are significantly different statistically from measurements after contrast material administration.
  
  
  METHODS
  Twenty-four patients with hepatic metastases from colorectal carcinoma underwent spiral computed tomography (CT) with 7-mm collimation. The liver was imaged before and in the portal-dominant phase after intravenous contrast material administration. For each scan, one to three discrete liver lesions were selected for measurement (n = 49). Three experienced radiologists performed independent measurements of the selected lesions on both pre- and postcontrast images at a computer workstation. A three-way analysis of variance (ANOVA) was performed: subjects by raters (the three independent radiologists) by pre- or postcontrast status. The dependent variable was the product of bidimensional measurements.
  
  
  RESULTS
  Sixty-seven percent (33 of 49) of the lesions were measured as larger on precontrast images; 33% (16 of 49), as smaller. There was high interrater reliability, with an intraclass correlation coefficient greater than 0.9 ANOVA showed significant subject, rater, and contrast material effects (P < .001) for the largest lesions in each liver. Contrast material status was a significant factor for all lesion sizes (P < .003).
  
  
  CONCLUSIONS
  On average, hepatic metastases from colorectal carcinoma are significantly smaller after contrast material administration.
authors.affiliation: Department of Radiology, Thomas Jefferson University Hospital, Philadelphia, PA 19107-5244, USA.
authors.forename: L N
authors.initials: LN
authors.lastname: Nazarian
authors.forename: J H
authors.initials: JH
authors.lastname: Park
authors.forename: E J
authors.initials: EJ
authors.lastname: Halpern
authors.forename: L
authors.initials: L
authors.lastname: Parker
authors.forename: P T
authors.initials: PT
authors.lastname: Johnson
authors.forename: A S
authors.initials: AS
authors.lastname: Lev-Toaff
authors.forename: R J
authors.initials: RJ
authors.lastname: Wechsler
mesh_terms: D000328:Adult; D000368:Aged; D001466:Barium Sulfate; D015179:Colorectal Neoplasms / Q000000981:diagnostic imaging*; D003287:Contrast Media; D003973:Diatrizoate; D003974:Diatrizoate Meglumine; D005260:Female; D006801:Humans; D007482:Iothalamate Meglumine; D008099:Liver / Q000000981:diagnostic imaging; D008113:Liver Neoplasms / Q000000981:diagnostic imaging / Q000556:secondary*; D008297:Male; D008875:Middle Aged; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed; D014283:Triiodobenzoic Acids
chemical_list: D003287:Contrast Media; D014283:Triiodobenzoic Acids; D003973:Diatrizoate; D001466:Barium Sulfate; D003974:Diatrizoate Meglumine; C054871:ioversol; D007482:Iothalamate Meglumine