Interim analysis was sufficient to demonstrate accuracy of the evaluated test

This study aims to evaluate the accuracy of dual energy computerized tomography (DE-CT) in predicting the need for surgery in patients with Crohn's disease and intestinal lesions with obstructive symptoms.

Patients with known Crohn's disease which were scheduled to perform abdominal CT for obstructive symptoms preformed it in a dual energy protocol and then followed for an outcome of surgery. DE-CT parameters were then compared between patients who underwent surgery and those who did not.

INTRODUCTION Intestinal strictures are common in patients with Crohn's (CD) disease and may result in intestinal obstruction. Current available imaging studies can usually identify and locate the stricture, but can not reliably differentiate the patients who will require surgery from those who will respond to medical therapy.

Dual Energy computerized tomography (DE-CT) uses two energy sources using high and low tube voltage, thus creating two data sets. Dedicated software creates overlay of the low and high energy images, in which enhancement of tissues with iodine can be better appreciated and quantified compared to standard CT. The investigators hypothesize that dual energy can better visualize the iodine uptake in bowl wall as a marker of inflammation within intestinal lesions, and may help in identifying the patients who will or will not require surgery.

AIM To evaluate the efficacy of DE-CT studies in predicting need for surgery within 3 months.

METHODS Patients with known CD undergoing abdominal CT for possible obstructive presentation prospectively underwent a DE-CT using intravenous iodinated contrast material, and were followed for 3 months for an outcome of surgery.

The DE-CT was interpreted by a radiologist blinded to the clinical outcome, and the attending physicians of the patients were blinded to the interpretation of the DE-CT. DE-CT parameters were then compared between patients who underwent surgery and those who did not. Receiver operating characteristic (ROC) curve analysis was used to find the optimal cut off point to distinguish between patients which did or did not eventually underwent surgery. Based on the cut off points found from the ROC analysis, the negative and positive predictive values were calculated.

Inclusion Criteria:

• Age over 18 years,
• known Crohn's disease (at least 3 moths prior)
• obstructive symptoms
• scheduled for abdominal CT for evaluation of symptoms (regardless of participation in the study)

Exclusion Criteria:

• Pregnancy
• Contraindication to perform CT with IV contrast media

Patients with known Crohn's disease undergoing abdominal CT for possible obstructive presentation