MRI Differentiating Gut TB and Crohn's

The clinical presentation of gut tuberculosis and Crohn's disease is very similar. In areas endemic of tuberculosis infection, differentiating the two diseases remains difficult. Both disease entities can have similar clinical, endoscopic and histological findings. Yet, wrongly diagnosing gut tuberculosis as Crohn's disease can potentially result in disastrous outcomes, especially when anti-tumor necrosis factor therapy, an important therapeutic option for Crohn's disease, can result in fulminant reactivation of tuberculosis.

Magnetic resonance enterography (MRE) is emerging as a effective imaging modality in evaluating the disease status of Crohn's disease. MRE, unlike computed tomography, emits no radiation, and is suitable for repeated serial imaging in younger-age populations. Ulcerations, strictures, transmural enhancement and mesenteric combing of the small bowel can be clearly demonstrated via MRE in Crohn's disease. Yet, the utilization of MRE in diagnosing gut tuberculosis remains largely unexplored. Whether MRE can be used to differentiate gut tuberculosis from Crohn's disease remains unknown.

The investigators plan to consecutively recruit 150 patients presenting to our hospital in Shenzhen, China, for new onset of lower gastrointestinal symptoms and ileocecal mucosal lesions of uncertain diagnosis as evidenced by the presence of inflammation, ulceration, strictures or nodules on colonoscopy.All recruited participants will undergo MRE, to be performed on a 1.5 Tesla scanner (Magnetom Avanto, Siemens Healthcare, Erlangen, Germany). MRE findings will be independently interpreted by two radiologists with special expertise in abdominal MR imaging and blinded to the patients' clinical data. The relationship between radiological patterns and clinical, endoscopic and histological findings will be analyzed. The role of MRE in distinguishing gut tuberculosis from Crohn's disease will be determined.

Inclusion criteria

• New-onset lower gastrointestinal symptoms of less than 3 months
• Ileocecal mucosal lesions of uncertain diagnosis as evidenced by the presence of inflammation, ulceration, strictures or nodules on colonoscopy.
• No prior tuberculosis treatment
• No prior immunomodulatory or anti-tumor necrosis factor treatment

Exclusion criteria

• Stage 4 or 5 chronic kidney disease, i.e. a glomerular filtration rate of <=30 ml/min.
• Contraindications to magnetic resonance imaging, including the installation of metallic devices or implants in-situ (e.g. pacemakers)
• Prior intestinal resection
• Known concomitant chronic small / large bowel disease, including ulcerative colitis, eosinophilic gastroenteritis, NSAID-related enterography etc.