Human umbilical cord blood relaxation times and susceptibility at 3 T

This is the peer reviewed version of the following article: Portnoy,S. , Milligan, N. , Seed, M. , Sled, J. G. and Macgowan, C. K. (2018), Human umbilical cord blood relaxation times and susceptibility at 3 T. Magn. Reson. Med, 79: 3194-3206. doi:10.1002/mrm.26978 which has been published in final form at https://doi.org/10.1002/mrm.26978. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived VersionsPurpose To characterize the magnetic susceptibility and relaxation times (T1 and T2) of fetal blood at 3 T as a function of the hematocrit (Hct) and oxygen saturation (sO2). Methods Susceptibility and relaxometry measurements were performed on cord blood specimens (N = 90, derived from six caesarean deliveries) with a range of hematocrits and oxygen saturations (0.09 < Hct < 0.82, 7 < sO2 < 100%). To obtain simple, analytic relationships between MRI properties and blood properties, data were fit to established two‐compartment (plasma and erythrocytes) models. Results Two‐compartment models effectively described the cord blood data. The root‐mean‐squared deviation between the model and the data was 6.3, 10.3, and 1.3% for fits to T1, T2, and susceptibility measurements. Relaxometry data and estimated T1 and T2 model parameters were generally consistent with those reported in cord blood at 1.5 T and comparable to published values for adult blood. Notably, the measured value of Δχdeo, the susceptibility difference between fully oxygenated (sO2 = 100%) and deoxygenated (sO2 = 0) cord blood was approximately 20% lower than the established adult blood value (Δχdeo,cord = 2.64 ppm, Δχdeo,adult = 3.4 ppm). Conclusions The described models and associated parameter values can be used to inform acquisition parameters, and interpret fetal/neonatal blood susceptibility measurements and relaxometry data acquired at 3 T with respect to hematocrit and sO2. Magn Reson Med 79:3194–3206, 2018. © 2017 International Society for Magnetic Resonance in Medicine.Canadian Institutes of Health Research . Grant Number: MOP13040