Venous oxygenation in sickle cell patients and controls using quantitative susceptibility mapping versus T2- relaxation-under-spin-tagging

In 15 homozygous sickle-cell disease patients (SCD; hemoglobin-SS) and 12 healthy controls (HC; 10 Hb-AA, 2 Hb-AS), we compared a quantitative susceptibility mapping (QSM)-based estimate of venous oxygen saturation (Yv) with T2-relaxation-under-spin-tagging (TRUST)-based estimates using bovine-hemoglobin (TRUST-HbBV), hemoglobin-S (TRUST-HbS), or hemoglobin-A (TRUST-HbA) calibrations. Agreement between methods varied, with QSM-Yv estimates in HC and SCD respectively on average 5-6% higher versus TRUST-HbBV, 5% higher and 9% lower versus TRUST-HbS, and 9% higher and 2% lower versus TRUST-HbA. Across all comparisons, the limits of agreement were wide (18-26%) underscoring the need for further studies comparing non-invasive methods with gold-standard jugular vein catheterization.