Pilot Study in the Use of Positron Emission Tomography-Computed Tomography (PET-CT)in the Management of Crohn's Disease

Crohn's disease (CD) is a gastrointestinal autoimmune disease thought to result from exposure to luminal antigen. This exposure then results in a robust Th1 mediated immune response which is not downregulated, resulting in intestinal tissue injury. Crohn's disease most commonly involves the distal small intestine, a site that can be difficult to visualize given its central location within the gastrointestinal tract.

A substantial proportion of patients do not respond to any of the standard therapies. Over 40% of patients do not respond to an initial anti-TNF (biologic) agent and approximately 10% per year lose their response to these drugs. There is no standard definition of what constitutes a patient who has primary biologic failure.

Disease activity is measured by indices such as the Crohn's Disease Activity Index (CDAI). The CDAI includes a combination of clinical criteria and lab values. However, the CDAI is limited by reliance on subjective criteria, limiting the score's use as a valid measure of studying response to medical therapy. Clinically, reliance on CDAI can result in inappropriate continuation of an ineffective therapy resulting in worsening of underlying disease, and increasing risk of adverse reactions.

Small studies have demonstrated that PET scans may accurately quantify disease activity in Crohn's. We propose to study CD patients with active flares to assess for a correlation between PET activity and CDAI. Additionally, we will determine whether PET signal intensity is predictive of clinical response to therapy with biologic agents.

The study proposes to test the hypothesis that PET can be used to determine which CD patients with small bowel disease will be true responders (or nonresponders) to biologic therapy at week 12. The use of PET to determine response to biologic therapy in small bowel Crohn's disease would be novel.