Reprint requests to: publications@acr.org Crohn Disease which occurs with water, allowing for increased distal luminal distention. If the patient cannot tolerate the oral contrast requirements of the enterography technique, CT can still be performed but with a loss of sensitivity. Although positive oral contrast often obscures the presence of subtle inflammation, it has been shown to improve detection of potential complications related to ongoing CD, including abscess formation, fistula and sinus tract formation, compared with neutral agents [16]. Thus, in some circumstances, positive luminal contrast may be the preferred agent at a standard CT to detect such complications. CT enterography or MR enterography involves oral ingestion by the patient, whereas CT enteroclysis and MR enteroclysis involves placement of a nasoduodenal tube to allow oral contrast infusion directly into the small bowel at a predetermined rate. These procedures are more invasive and may not be well tolerated by acutely ill patients. The technical demands of the enteroclysis protocol related to placement of a nasoduodenal tube and the need for radiologist monitoring throughout the procedure have been negative impediments to widespread use. Bowel distention of the jejunum is typically less at enterography than at enteroclysis but is considered acceptable with good technique [17,18]. CT Enterography CT enterography represents a CT examination with a specialized protocol. Neutral contrast by mouth is given in large amounts over a set time to promote optimal distention of the small bowel [19-21]. Combined with other technical modifications, including thin collimation, multiplanar reconstruction, and intravenous (IV) contrast, this protocol maximizes the technique to depict inflammatory changes in the small bowel related to CD [20,22,23]. It is difficult to precisely determine the test characteristics in CD exactly because of the lack of a true reference standard.
Crohn Disease. Reprint requests to: publications@acr.org Crohn Disease which occurs with water, allowing for increased distal luminal distention. If the patient cannot tolerate the oral contrast requirements of the enterography technique, CT can still be performed but with a loss of sensitivity. Although positive oral contrast often obscures the presence of subtle inflammation, it has been shown to improve detection of potential complications related to ongoing CD, including abscess formation, fistula and sinus tract formation, compared with neutral agents [16]. Thus, in some circumstances, positive luminal contrast may be the preferred agent at a standard CT to detect such complications. CT enterography or MR enterography involves oral ingestion by the patient, whereas CT enteroclysis and MR enteroclysis involves placement of a nasoduodenal tube to allow oral contrast infusion directly into the small bowel at a predetermined rate. These procedures are more invasive and may not be well tolerated by acutely ill patients. The technical demands of the enteroclysis protocol related to placement of a nasoduodenal tube and the need for radiologist monitoring throughout the procedure have been negative impediments to widespread use. Bowel distention of the jejunum is typically less at enterography than at enteroclysis but is considered acceptable with good technique [17,18]. CT Enterography CT enterography represents a CT examination with a specialized protocol. Neutral contrast by mouth is given in large amounts over a set time to promote optimal distention of the small bowel [19-21]. Combined with other technical modifications, including thin collimation, multiplanar reconstruction, and intravenous (IV) contrast, this protocol maximizes the technique to depict inflammatory changes in the small bowel related to CD [20,22,23]. It is difficult to precisely determine the test characteristics in CD exactly because of the lack of a true reference standard.