In vivo MRI measurement of blood oxygen saturation in children with congenital heart disease

Objective: The purpose of this prospective study was to measure in vivo blood oxygen saturation (%O-2) by MRI in children with congenital heart disease (CHD) using population-based values for T2O (T-2 signal decay of fully oxygenated blood) and K (a parameter representing the deoxyhemoglobin effect) and compare the %O-2 with direct cardiac catheterization measurements. Background: MRI can determine %O-2 using in vivo measurement of signal decay (T-2) and an in vitro calibration curve relating T-2 and %O-2, based on the equation: 1/T-2=1/T2O+K(1-%O-2/100)(2). Recent studies have correlated the T-2/%O-2 in children with CHD with the adult calibration statistics. Methods: A total of ten children (five male, five female) with single ventricle CHD (median age 4.8 months, range 2 months to 4.4 years) undergoing cardiac catheterization were included in the study. The blood T-2 measurements for each patient were performed in a 1.5 T GE CV scanner. The %O-2 was then calculated based on the equation using values of T2O determined from individual hematocrits, and a population average value of K derived for children. The %O-2 values were compared with direct %O-2 measurements from cardiac catheterization. Results: The %O-2 values by MRI were strongly correlated with direct cardiac catheterization measurements (R=0.825; P<0.001). Conclusion: The study indicates that the noninvasive measurement of %O-2 by MRI can accurately measure oxygen saturation in children with complex CHD.