13-Year-Old Boy with a 3-Day History of Melena

A 13-y-old boy presented to the emergency center with a 3-d history of melena. On admission the patient was anemic (hemoglobin = 9.3 g/dL, hematocrit = 26.2%). The patient was injected with 334 MBq (9 mCi) of 99mTc-pertechnetate. Anterior, posterior, and lateral views of the abdomen were acquired at