In this study the investigators will, with an Magnetic Resonance Imaging (MRI) method, measure the oxygen content in the portal vein, which conduct the blood from the guts to the liver. Examinations will be performed on 20 subjects with meal related abdominal pain due to severe narrowing of the vessels conduction blood to the guts,compared to 20 subjects with similar narrowing of the abdominal vessels, but without meal related pain. The goal of the study is to test a non-invasive, radiation free method to diagnose patients with abdominal pain due to compromized blood supply (chronic mesenteric ischemia).