Accuracy of the Cylinder Approximation for Susceptometric Measurement of Intravascular Oxygen Saturation Versus Numerical Calculation of Induced Field

Cheng Li¹, Michael C. Langham¹, Jeremey F. Magland¹, Charles L. Epstein^1,2, Jue Wu¹, James C. Gee¹, Felix W. Wehrli¹

Quantification of blood oxygen saturation level in large vessels with MR susceptometry-based oximetry has previously been used for quantifying peripheral vascular reactivity and global cerebral metabolic rate of oxygen utilization. A key assumption underlying this method is modeling large vessels as long paramagnetic cylinders. Here, we evaluate the long cylinder approximation by numerically computing the induced magnetic field of 3D segmented femoral vein and superior sagittal sinus. Analytical and numerical solutions were found to be in good agreement for tilt angles less than 40o despite vessel tapering and curvature.