A 70-year-old woman complained of sudden onset of severe abdominal pain in the epigastric region which was progressively increasing rapidly. She has a history of myocardial ischemia and peripheral vascular disease. The patient states that she has had nausea and vomiting. On examination, she was writhing in pain. Bowel sounds were normal and there was minimal tenderness. A small amount of blood was present in the stool specimen.The electrolytes showed bicarbonate level at 15 mEq/L, and the serum lactate level was high, which were indicative of tissue receiving insufficient oxygenation leading to tissue injury. CT was planned with following finding. (source - radiopedia.org) What anatomical structure is likely involved?