Chronic mesenteric ischemia: use of in vivo MR imaging measurements of blood oxygen saturation in the superior mesenteric vein for diagnosis.

PURPOSE: To determine if dogs and humans with chronic mesenteric ischemia demonstrate a decrease in the percentage of oxygenated hemoglobin (%HbO2) in the superior mesenteric vein (SMV) after a meal.

MATERIALS AND METHODS: In 10 dogs, ameroid rings were surgically implanted around the superior mesenteric arteries to create gradual stenosis. Pre- and postoperative angiograms and pre- and postprandial magnetic resonance (MR) oximetry measurements of the SMV %HbO2, with flow-independent T2 measurements of venous blood, were obtained at different times. In 10 patients with atherosclerotic disease and six patients with symptomatic chronic mesenteric ischemia, the same measurements were obtained after at least 6 hours of fasting and at 15, 35, and 45 minutes after ingestion of a liquid nutritional supplement.

RESULTS: In seven dogs, the postprandial SMV %HbO2 increased an average of 2.5% +/- 0.8 before surgery and decreased an average of 6.3% +/- 2.1 when hemodynamically significant (>70%) stenosis of the superior mesenteric artery developed 7-14 days after surgery. In the 10 patients without ischemia, the SMV %HbO2 increased by 4.6% +/- 0.6, whereas in the symptomatic patients a postprandial decrease of 8.8% +/- 0.7 occurred (P < .0001).

CONCLUSION: Measurement of the SMV %HbO2 with MR oximetry is a promising test for diagnosis of chronic mesenteric ischemia.