Final answer:
CT angiography is generally the preferred imaging study for the diagnosis of acute mesenteric ischemia, providing fast and detailed images necessary for diagnosing vascular blockages or abnormalities.
Step-by-step explanation:
To diagnose acute mesenteric ischemia, the most appropriate choice would be CT angiography. This is because CT angiography provides detailed images of the blood vessels and can help identify blockages or other abnormalities that are characteristic of mesenteric ischemia. While other imaging modalities like Magnetic Resonance Angiography (MRA) and Ultrasound can also be used, CT angiography is often the first choice due to its speed, availability, and high-resolution images that are useful for making a quick diagnosis in acute situations.
However, if available and in cases where the patient has contraindications to iodinated contrast used in CT angiography, MRA could be considered a non-invasive alternative. It should be noted that an abdominal X-ray is not usually diagnostic for this condition, and while it might show complications such as bowel gas patterns suggesting intestinal ischemia or perforation, it is not the imaging modality of choice.