Oxygen saturation of blood in the superior mesenteric vein: in vivo verification of MR imaging measurements in a canine model. Work in progress.

Abstract

To evaluate the accuracy of magnetic resonance (MR) imaging in estimating oxygen saturation of blood (%HbO2) in the superior mesenteric vein (SMV) of a canine model in vivo. MR imaging was used to measure the T2 of blood in samples obtained via a catheter placed in the SMV in seven mongrel dogs. %HbO2 was measured with a reflectance oximeter. These measurements were obtained at the resting state, during superior mesenteric artery occlusion, and after reperfusion. MR imaging and oximeter measurements were then compared by using linear regression analysis. Refocusing intervals (tau 180) of 12 and 24 msec were used for 17 and 18 %HbO2 measurements with MR imaging, respectively. With tau 180 of 12 msec, there was an excellent correlation between MR imaging measurements and oximeter measurements (r = .969). The intercept was 5.3% and the slope was 0.959. With tau 180 of 24 msec, r = .953, the intercept was 15.4%, and the slope was 0.817. Estimates of %HbO2 in the SMV with MR imaging are accurate in the range of most clinical interest.