Novel PET scan improves diagnosis, monitoring of inflammatory bowel disease

Immuno-PET offers a more efficient diagnosis of inflammation in inflammatory bowel disease (IBD) compared to traditional invasive methods, according to a new study published in the June issue of the Journal of Nuclear Medicine.

Nearly three million adults in the U.S. live with IBD, which includes diseases such as Crohn’s and ulcerative colitis, wrote co-author Patrick A. Hughes, PhD, head of the Gastrointestinal Neuro-immune Interactions Group at the University of Adelaide in Australia. Patients experience chronic relapsing and remitting inflammation in the lower gastrointestinal track, which must be constantly monitored and comes with an increased risk of colon cancer.

“The diagnosis and maintenance of IBD is heavily reliant on endoscopy, which is invasive and does not provide real-time information regarding the role of specific mediators and drug targets,” said Hughes in a prepared statement. “There is a need to develop less invasive tools that provide quick diagnostic information for IBD. This is particularly relevant when the area of inflammation is beyond the reach of the endoscope, such as difficult-to-access regions of the small intestine, and in patient populations that have increased risk in endoscopy, including pediatrics and hemophiliacs.”

In their study, the authors compared immune-PET with 89Zr-conjugated antibodies against IL-1β and CD11b versus the ability of 18F-FDG PET and magnetic resonance imaging (MRI) to detect inflammation in mice with ulcerative colitis and healthy controls. CD11b is a cell surface receptor that marks the innate immune cells, which, when activated, are linked to inflammation. These surface receptors secrete IL-1β to create immune responses.

The researchers compared body weight loss, colon shortening and epithelial barrier permeability between the two mouse groups, measuring the levels of IL-1β and CD11b concentration.

In colitic mice imaged with immune-PET, distal colinic uptake of 89Z-α-IL-1β was increased by approximately three-fold, uptake of 89Z-α-CD11b was increased by approximately five-fold and uptake of 18F-FDG was increased approximately 3.5-fold. MRI showed an approximate two-fold increase in the T2 signal intensity ratio in mice with colitis. A “robust positive correlation” was seen in colonic uptake of 18F-FDG and percentage body weight loss, with a strong trend toward a similar effect observed for 89Z-α-IL-1β, but not for 89Z-α-CD11b, the researchers noted.

Overall, the results showed immune-PET may offer a superior method for diagnosing and monitoring IBD and other inflammatory diseases.

“These findings are important for inflammatory diseases in general, as many of the biologics used to treat these diseases are directed against specific immune mediators; however, these drugs are also associated with primary and secondary non-response,” Hughes said. “Future refinements will lead to theranostic applications where the efficacy of drugs can be rapidly and non-invasively determined, leading to precision treatment not only in IBD, but also in other inflammatory diseases.”