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: Fe2+ or Ca2+-loaded DCBs were prepared by mixing DCBs in 100 mM FeSO4 or CaSO4 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 FeSO4 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 FeSO4 and CaCl2 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 FeSO4 solution increased and achieved equilibrium at 120 min, and was 120.5 and higher than in the other FeSO4 solutions. The SNR of blood was 49.7. CONCLUSION: Optimally Fe2+-loaded DCBs can be discriminated from venous blood on 40-keV monochromatic images from DECT and T1-GRE.

Detection of Increased Vascular Signal in Arthritis-Prone Rats Without Joint Swelling Using Superb Microvascular Imaging Ultrasonography.

This study aimed to determine whether ultrasonography (US) can detect increased vascular signal in the synovial tissue before overt synovitis in rheumatoid arthritis (RA). Env-pX rats that spontaneously develop RA-like synovitis were used. Ankle joints of 15 pre-morbid env-pX rats were observed with power Doppler and superb microvascular imaging (SMI) using an ultrahigh-frequency (8-24 MHz) probe. Signal values were counted as the number of pixels. The total number of vessels and vessel area in the synovial tissue were histologically evaluated. Dilated vessels were determined from the mean value of synovial vessels in three wild-type rats. In all env-pX rats, apparent synovial proliferation was not observed. However, vasodilation was evident. Only SMI values were significantly correlated with the number of dilated vessels (r = 0.585, p = 0.022) but not with the total number of vessels. US with SMI using ultrahigh-frequency probe can detect increased vascular signal in the synovial tissue of arthritis-prone rats.