Magnetic resonance angiography can be used if the source of bleeding can't be found using the more conventional methods.
Angiodysplasia MRI
Angiodysplasia CT
Fibromuscular dysplasia arteriography
Angiodysplasia physical examination
Takayasu's arteritis physical examination
Varicose veins MRI
Portal hypertension MRI
Carcinoid syndrome MRI