Predicting the Need for Imaging in IBD: Radiating Only Badness?

Multiple imaging tests are needed to diagnose, evaluate symptoms of, and manage Crohn’s disease (CD) patients, with particular regard to excluding complications such as obstruction, perforation, and abscess [1]. Imaging modalities used in evaluating CD include conventional radiography, fluoroscopy, computed tomography (CT), ultrasound (US), and magnetic resonance imaging (MRI) [1]. CT use has increased extensively in general but especially for those with CD, raising concerns about the effects of radiation exposure and subsequent risk of cancer [2]. The estimated lifetime attributable risk of malignancy from a single abdominal-pelvic CT scan is *0.7 % [3]. The radiation exposure from a single CT scan can vary greatly based on scanner type, protocol settings, and patient size, with newer protocols that reduce radiation exposure increasingly utilized [4, 5]. CT, especially CT enterography (CTE), is considered the ‘‘gold-standard’’ imaging examination for patients with symptomatic CD. CT provides critical information to treating physicians regarding the presence or absence of disease, disease activity, severity of disease, and complications of penetrating disease such as abscess. Supporting this, a recent study reported that CT performed in the emergency department (ED) changed the management of 81 % of patients with CD with urgent findings in 48 % (35 % penetrating or obstructive disease, 13 % non-IBD urgent findings) [6]. One-third of the patients in this study had a cumulative effective dose (CED) of [75 millisieverts (mSv). Thus, CT remains a ‘‘doubleedged sword’’ given its associated radiation exposure, particularly for younger patients. Multiple retrospective studies have reported radiation exposures in CD patients to be higher than that of the general population [7, 8]. The use of CT in patients with inflammatory bowel disease (IBD) has increased noticeably in the last decade with an 840 % increase from 2003 to 2007 reported at one institution [9]. A retrospective cohort study of 415 patients over 20 years found that usage of CTs increased by 310 % and that 1 in 13 patients was exposed to potentially harmful levels of ionizing radiation defined as CED[50 mSv. A history of IBD-related surgery was a risk factor for high exposure [10]. CD patients are commonly diagnosed in their 20s and 30s with *20 % diagnosed during childhood [11]. Furthermore, there is an increased risk of radiation-induced malignancies in patients exposed at a younger age given the elevated biologic activity of their tissues and the longer available ‘‘lag-time’’ for the development of malignancy [12]. A recent study by Brenner and Hall [13] suggests that it is not until patients reach 35 years of age that the risks of ionizing radiation decrease substantially. Since many of the CT scans in CD patients are performed acutely in the ED, it is important to evaluate whether there are predictors of positive or negative factors that would maximize benefit and minimize risk of imaging in this setting. Previous studies of CT use in IBD have identified several risk factors associated with higher radiation exposure. Levi et al. [14] from a single IBD center in Israel reviewed 199 CD and 125 UC patients and reported on the basis of multivariate analysis that IBD-related surgery, CD, prednisone use, first year of diagnosis, and age in the upper quartile were independent predictors. Butcher et al. [15] from a single-center retrospective review of 280 consecutive IBD patients reported that CD, S. A. Shah Gastroenterology Associates, Inc., 44 West River Street, Providence, RI 02904, USA