From the Research
The mesenteric aorta ratio (MAR) is a radiological measurement used to assess for mesenteric ischemia, particularly chronic mesenteric ischemia, and is calculated by dividing the diameter of the superior mesenteric artery (SMA) by the diameter of the adjacent aorta at the same level on CT imaging, with a normal MAR typically being greater than 0.4, as suggested by the most recent and highest quality study available 1.
Key Points to Consider
- The MAR is a useful measurement for evaluating patients with symptoms of chronic mesenteric ischemia, such as postprandial abdominal pain, weight loss, and food fear.
- A ratio below 0.4 may suggest significant stenosis of the SMA, leading to inadequate blood flow to the intestines.
- The MAR accounts for individual variations in vessel size by comparing the SMA to the patient's own aorta, rather than using absolute measurements.
- When used alongside other clinical and imaging findings, the MAR can contribute to diagnostic decision-making and help determine if further vascular intervention is warranted.
Relevant Studies
- A study published in 2022 1 found that the normal range of aorto-SMA angle and distance in the Iraqi population was wider than previously reported, with a significant reduction in values in underweight participants, female patients, and those younger than 20.
- Another study published in 2021 2 found that patients with severe aortic stenosis were at a higher risk for mesenteric artery stenosis, and that chronic mesenteric ischemia should be considered in patients with symptoms such as non-specific abdominal pain and weight loss.
Clinical Implications
- Clinicians should consider using the MAR as a diagnostic tool for evaluating patients with suspected chronic mesenteric ischemia.
- Further vascular intervention may be warranted in patients with a low MAR, and clinicians should use their clinical judgment to determine the best course of treatment.
- The MAR should be used in conjunction with other clinical and imaging findings to ensure accurate diagnosis and treatment.