MR imaging of the liver and spleen: A comparison of the effects on signal intensity of two superparamagnetic iron oxide agents

We compared the effects of two superparamagnetic iron oxide (SPIO) contrast agents, ferumoxides and SHU-555A, in MR imaging of the liver and spleen. Thirty-six patients with known malignant lesions of the liver underwent T2W turbo spin-echo (TSE) and T(1)WGRE FLASH opposed-phase imaging before and after SPIO injection on a 1.0 T MR system. Post-ferumoxides images were obtained in 18 patients 90 min after infusion of 15 mu mmol Fe/kg of the agent. In 18 other patients SHU-555A was administered as a rapid bolus at a dose of 7.0 similar to 12.9 mu mmol Fe/kg, T(1)WGRE FLASH images were obtained immediately, 30 s and 480 s and T2WTSE images 10 min after injection. Signal intensity of the liver, spleen, and malignant liver lesions before and after SPIO was measured with operator-defined regions of interest. The effects of ferumoxides and SHU-555A were measured as the percentage signal intensity change (PSIC) and in the malignant liver lesions additionally as changes in lesion-to-liver contrast-to-noise ratio (Delta DCNR). On T2W TSE images, there was no significant difference between the two agents in signal loss of liver parenchyma (p > 0.05), The signal loss in the spleen produced by ferumoxides was greater than with SHU-555A (p < 0.05), Both SPIO agents produced a significant increase in the CNR of malignant liver lesions. Delta CNR was slightly greater with ferumoxides than with SHU-555A (p < 0.05), On T(1)WGRE FLASH images, a slight decrease of liver SI induced by both agents was found on late post-SPIO images. No significant difference of liver PSIC between the two SPIO agents was noted on T1W images. The SI of spleen was significantly increased with both agents on T1W images and no difference in PSIC of spleen was noted (p > 0.05). The T-1 and T-2 effects produced by ferumoxides and SHU-555A were comparable in the liver although ferumoxides produced a stronger T-2 effect in the spleen. (C) 1999 Elsevier Science Inc.