Chronic Mesenteric Ischemia: This condition is characterized by the narrowing or occlusion of the mesenteric arteries, leading to reduced blood flow to the intestines. The symptoms and imaging findings, such as those from a CTA, can help identify this condition as the most likely diagnosis due to its direct impact on the mesenteric vessels.

Acute Mesenteric Ischemia: This is a sudden onset of insufficient blood flow to the intestines, which can be due to an embolus, thrombosis, or venous thrombosis. A CTA can help identify the occlusion or significant narrowing of the mesenteric vessels, making this a likely diagnosis.
Mesenteric Venous Thrombosis: This condition involves a blood clot in the veins that drain blood from the intestines. While less common than arterial occlusion, it can still cause ischemia and is identifiable on a CTA.
Non-occlusive Mesenteric Ischemia: This condition occurs when there is a low blood flow state without a fixed occlusion of the mesenteric arteries, often seen in critically ill patients or those with heart failure. A CTA might show indirect signs or normal findings, but clinical correlation is key.

Dissection of the Aorta or Mesenteric Arteries: Although less common, a dissection can lead to acute mesenteric ischemia by compromising blood flow. Missing this diagnosis could be catastrophic, making it crucial to consider, especially if the patient presents with severe abdominal pain and a history suggestive of aortic disease.
Vasculitis: Inflammatory diseases affecting the blood vessels, such as polyarteritis nodosa, can cause ischemia by narrowing or weakening the vessel walls. While less likely, the consequences of missing vasculitis can be severe, necessitating its consideration.

Fibromuscular Dysplasia: A rare condition that affects the medium and large arteries, most commonly the renal and internal carotid arteries, but can also involve the mesenteric arteries, leading to stenosis or aneurysms.
Median Arcuate Ligament Syndrome: A rare condition where the median arcuate ligament compresses the celiac trunk, potentially leading to chronic mesenteric ischemia. It's more of a consideration in younger patients with chronic abdominal pain and weight loss.
Thromboangiitis Obliterans (Buerger's Disease): A rare disease of the blood vessels in the arms and legs, which can also affect the mesenteric vessels, leading to ischemia. It's primarily seen in young smokers.