Feasibility of Ferumoxytol-enhanced MRI for Detection of Gastrointestinal Bleeding when Conventional Evaluation is Negative

Background The evaluation of gastrointestinal (GI) bleeding is frequently negative despite a prolonged workup involving several different radiologic and endoscopic tests. Ferumoxytol, a superparamagnetic iron oxide agent used for treatment of iron deficiency anemia, can be used off label as a blood pool contrast agent at MRI. Purpose To perform a proof-of-concept study to determine if Ferumoxytol-enhanced MRI (FeMRI) can be performed to assist in detecting the presence and location of GI bleeding in patients who have undergone a negative standard evaluation. Methods A retrospective convenience cohort of patients examined with FeMRI at a single center over a 2-year period was evaluated. Inclusion criteria included clinical suspicion for slow or intermittent, active GI bleeding not localized following conventional testing. Exclusion criteria included any allergy to ferumoxytol or iron containing agents, additional MRI scans scheduled within the following 72 hours, current pregnancy or breast feeding, history of medication related hypotensive episodes not related to an acute illness, syncopal events, arrhythmia, or low resting blood pressure. The patient’s clinical characteristics, exam results and outcome during their hospital stay were examined. Results 5 males and 1 female with average age of 66 years (range 37 to 79 years) were imaged with FeMRI. All had undergone full diagnostic evaluation of the GI tract including upper and lower endoscopy, small bowel evaluation with imaging and/or endoscopic testing; in all patients repeated rounds of testing were performed. Diagnostic images were obtained in all patients who underwent FeMRI. In 4/6 (67%) patients FeMRI demonstrated active bleeding in the small bowel (n = 3) and colon (n = 1). Conclusion FeMRI was able to demonstrate the presence and location of active GI bleeding in hospitalized patients with previous extensive negative evaluation. FeMRI should be further evaluated to determine its performance characteristics as an exam in the evaluation of GI bleeding patients.