RESUMEN
OBJECTIVE: Superparamagnetic iron oxide (SPIO) particles are phagocytosed by cells of the macrophage-monocytic phagocytic system. They are usually used in MRI as a negative contrast agent, because of their strong T2* effect, to improve detection of tumors in the liver and spleen. However, they also have a potent T1 relaxivity. In the current study, we describe this T1 effect in liver hemangiomas. MATERIALS AND METHODS: Twelve patients (nine women and three men, aged from 38 to 76 years) with liver hemangiomas were examined by means of MRI at 1.5 T before and after intravenous administration of SPIO particles at a dose of 15 mumol Fe/kg body wt. Signal intensity was measured from regions of interest. RESULTS: Whereas on postcontrast T2-weighted SE images the hemangiomas showed on average a signal drop of 20% (p = 0.011) and 49% (p = 0.001) (first and second echo, respectively), their signal increased by 106% (p = 0.001) on postcontrast T1-weighted SE images. CONCLUSION: The T1 effect (signal enhancement) we observed in liver hemangiomas after infusion of SPIO particles could prove to be a useful new diagnostic feature that would help characterize these common lesions and differentiate them from other liver tumors.