Hassan Siddiki MD, Presenter: Nothing to Disclose

Jeff Lynn Fidler MD, Abstract Co-Author: Grant, E-Z-EM, Inc, Lake Success, NY

Joel Garland Fletcher MD, Abstract Co-Author: Research grant, Siemens AG Grant, E-Z-EM, Inc License agreement, General Electric Company

James E. Huprich MD, Abstract Co-Author: Nothing to Disclose

David Maitland Hough MD, Abstract Co-Author: Nothing to Disclose

Sharon Steele Burton MD, Abstract Co-Author: Nothing to Disclose

C. Daniel Johnson MD, Abstract Co-Author: License agreement, General Electric Company License agreement, E-Z-EM, Inc

David Bruining MD, Abstract Co-Author: Nothing to Disclose

et al, Abstract Co-Author: Nothing to Disclose

To assess discordant observations at CT Enterography (CTE), MR Enterograpy (MRE), and ileoscopy, compared to a clinical reference standard in the evaluation of Crohn Disease (CD).

30 patients with known or suspected CD underwent evaluation with CTE, MRE, and colonoscopy with ileoscopy. CTE and MRE were reviewed separately by two blinded radiologists (for a total of 4 independent interpretations) for evidence of active disease. A consensus interpretation was performed for discrepant results. The reference standard was created by a gastroenterologist and incorporated all clinical parameters, imaging and endoscopic findings, and biopsy results. Cases with false negative (FN) or false positive (FP) consensus interpretations were reviewed by a separate unblinded radiologist to determine potential reasons for error. Ileoscopic errors were classified into different types depending on ability to cannulate the ileum and perform biopsies.

The sensitivity for CTE and MRE compared to a clinical reference standard was 95.2% and 90.5% respectively. There was one case with both false negative CTE and MRE results likely secondary to occult disease. There was an additional false negative MRE secondary to perception. There was one false positive CTE secondary to suboptimal distension. There were 3 false positive MRE cases (suboptimal distension 2; fibrosis 1). There were 11 (37%) cases where ileoscopy did not detect active small bowel inflammation that was seen with imaging. There were four failed ileoscopies with positive CTE and MRE. Three patients (10%) had normal appearing ileoscopy without biopsy but active small bowel inflammation either intramural (n=1) or proximal disease (n=2) by imaging. Another three (10%) had negative ileoscopy and biopsy but positive small bowel inflammation in the terminal ileum at imaging (sampling error). Finally one patient had negative ileoscopy with biopsy concurring with positive CT and MR findings.

1. Suboptimal distension and fibrosis can lead to false positive results on both CTE and MRE. 2. Ileoscopy can fail to detect active small bowel inflammation detected at CTE and MRE due to inability to cannulate the TI, intramural or proximal disease, and sampling error.

CTE and MRE can detect active Crohn Disease missed by ileoscopy.  Adequate small bowel distension is critical to reduce false postive examinations at CTE and MRE.

Siddiki, H, Fidler, J, Fletcher, J, Huprich, J, Hough, D, Burton, S, Johnson, C, Bruining, D, et al, , Understanding Pitfalls and Limitations of CT Enterography, MR Enterography, and Ileoscopy in Detecting Active Crohn Disease in the Small Bowel Using a Clinical Reference Standard.  Radiological Society of North America 2008 Scientific Assembly and Annual Meeting, February 18 - February 20, 2008 ,Chicago IL. http://archive.rsna.org/2008/6017382.html