CT beats gold standard in detection of Crohn’s disease abnormalities

CT can outclass fluoro-based enteroclysis, the current imaging standard for small bowel evaluation in patients with Crohn's disease, according to a new study from Austria.

A significant number of patients with inflammatory or obstructive lesions and other complications related to Crohn's disease require immediate treatment. CT's ability to detect these complications and the extent of disease accurately could prove crucial for the proper management of these patients, said principal investigator Dr. Johannes Sailer, a radiologist at the Medical University of Vienna.

"The big advantage of CT enteroclysis is its ability to detect complications that exist outside normal parameters of the diagnosis and identification of Crohn's disease," Sailer said.

Sailer and colleagues enrolled 50 patients with Crohn's disease who underwent CT and conventional enteroclysis while symptomatic. The investigators compared each modality's ability to detect disease and evaluate its implications. They then matched results against surgery and follow-up (AJR 2005;185;1575-1581).

They found that CT enteroclysis proved better than conventional enteroclysis at detecting fistulae, abscesses, and conglomeration of small bowel loops. CT enteroclysis proved equivalent to standard imaging in the detection of minimal mucosal changes, a sign of early-stage Crohn's disease.

Both CT and fluoroscopic enteroclysis were successfully performed in all 50 patients. Significantly more Crohn's disease-associated abnormalities were diagnosed with CT enteroclysis, however, than with the conventional method (p<0.01). CT and conventional enteroclysis detected minimal mucosal inflammation in 88% and 84% of patients and prestenotic dilatation in 40% and 30% of patients, respectively.

Both imaging methods detected stenotic bowel segments in 68% of patients. CT found fistulae, skip lesions, and conglomerations of bowel loops in 36%, 34%, and 26% of patients, respectively. Conventional enteroclysis confirmed the same lesions on 16%, 6%, and 6% of patients, respectively. Only CT detected abscesses in eight patients.

"CT enteroclysis can also be performed in follow-up exams of patients. These results can help the clinicians in adapting their treatment and in deciding whether a surgical resection is needed," Sailer said.

The study has several limitations, however, including selection bias and the time gap between imaging procedures. All patients in the study had well-known, documented Crohn's disease for several years. The high prevalence of disease in the study population thus provided skewed sensitivity and specificity rates, the investigators warned.

In addition, the mean interval of 21.7 days between exams may not reflect the chronic and recurrent course of this condition. The status of the inflammation might have changed - for better or worse - over the three-week lapse.

On the brighter side, the study used a single-slice CT scanner, underscoring multislice CT's potential for diagnosis of all small bowel diseases. Medical University of Vienna radiologists already use CT to detect bowel wall pathologies, especially in patients with inflammatory bowel disease. It has become the institution's standard imaging procedure for the diagnosis of lymphoma and other intestinal tumors.

"CT enteroclysis is the imaging method of choice and should replace conventional enteroclysis in patients with Crohn's disease," Sailer concluded.

For more information from the Diagnostic Imaging archives:

Fishman urges radiologists to capitalize on 64-slice capabilities

MR aids evaluation of pediatric Crohn's disease

MR and CT for Crohn's stay in two different worlds

Oral contrast makes MR enteroclysis more palatable