The opacity of mineral ion-loaded bead (DC beads®) on low-keV monochromatic images from dual energy CT and T1-weighted gradient-echo MRI

Purpose To evaluate the opacity of DC beads ® (DCB) loaded with mineral ions on low-keV monochromatic images from dual energy computed tomography (DECT) and T1-weighted gradient-echo (T1-GRE) MRI. Materials and methods Fe 2+ or Ca 2+ -loaded DCBs were prepared by mixing DCBs in 100 mM FeSO 4 or CaSO 4 solution and scanned by DECT from 10 min to 27 h after mixing. The Hounsfield units (HUs) of sedimented DCBs on 40-keV monochromatic images were measured. Next, we mixed DCBs in 100, 10, 5 and 1 mM FeSO 4 solutions, and scanned these solutions from 15 to 120 min after mixing using a 3 T MR scanner. The signal–noise ratios (SNRs) of sedimented DCBs on T1-GRE were measured. Venous blood was scanned to compare with DCBs. Results The CT values of DCBs in FeSO 4 and CaCl 2 solutions gradually increased, and were 113.3 and 43.1 HU at 27 h, respectively; that of blood was 17.8 HU. The SNR of DCB in 1 mM FeSO 4 solution increased and achieved equilibrium at 120 min, and was 120.5 and higher than in the other FeSO 4 solutions. The SNR of blood was 49.7. Conclusion Optimally Fe 2+ -loaded DCBs can be discriminated from venous blood on 40-keV monochromatic images from DECT and T1-GRE.