title: Fluid tagging for CT colonography: effectiveness of a 2-hour iodinated oral preparation after incomplete optical colonoscopy.
abstract: OBJECTIVE
  To evaluate the distal extent and attenuation of bowel opacification achieved after administration of a single low volume dose of oral contrast 2 hours before computed tomographic colonography (CTC) after incomplete optical colonoscopy.
  
  
  METHODS
  This retrospective study included 144 patients undergoing CTC after incomplete colonoscopy from April 2006 to July 2008 at 2 separate medical centers. Each patient received 20 to 30 mL of diatrizoate meglumine and diatrizoate sodium solution 2 hours before being scanned.
  
  
  RESULTS
  The distalmost extent of opacification was: stomach/small bowel, n = 13; cecum, n = 2; ascending colon, n = 7; transverse colon, n = 19; descending colon, n = 14; sigmoid colon, n = 24; rectum, n = 65. The mean attenuation of each opacified segment was: cecum, 449 Hounsfield units (HU); ascending colon, 474 HU; transverse colon, 468 HU; descending colon, 421 HU; sigmoid colon, 391 HU; and rectum, 382 HU. In 103 (71.5%) patients, oral contrast reached the distal colon (descending colon, sigmoid colon, or rectum). The oral contrast did not reach the colon in only 13 (9.0%) patients.
  
  
  CONCLUSIONS
  Oral administration of a small volume hyperosmolar oral contrast agent 2 hours before CTC results in satisfactory colonic opacification in the majority of patients. Adding same-day fluid tagging in incomplete colonoscopy patients presenting for completion CTC should result in adequate fluid opacification for most of the colon, especially proximal segments not visualized at the time of incomplete colonoscopy.
authors.affiliation: Department of Diagnostic Imaging, Rhode Island Hospital and Brown University Alpert Medical School, Providence, RI 02903, USA. kchang@lifespan.org
authors.forename: Kevin J
authors.initials: KJ
authors.lastname: Chang
authors.forename: Satinder S
authors.initials: SS
authors.lastname: Rekhi
authors.forename: Stephan W
authors.initials: SW
authors.lastname: Anderson
authors.forename: Jorge A
authors.initials: JA
authors.lastname: Soto
mesh_terms: D000284:Administration, Oral; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002400:Cathartics / Q000008:administration & dosage; D003108:Colonic Diseases / Q000000981:diagnostic imaging*; D023881:Colonography, Computed Tomographic / Q000379:methods*; D003113:Colonoscopy / Q000379:methods*; D003287:Contrast Media / Q000008:administration & dosage*; D003973:Diatrizoate / Q000008:administration & dosage*; D003974:Diatrizoate Meglumine / Q000008:administration & dosage*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011857:Radiographic Image Interpretation, Computer-Assisted; D012189:Retrospective Studies; D013997:Time Factors
chemical_list: D002400:Cathartics; D003287:Contrast Media; D003973:Diatrizoate; D003974:Diatrizoate Meglumine