RESUMO
Objective To investigate the MR imaging technique and features of acute radiation- induced hepatic injury with superparamagnetic iron oxide(SPIO)enhancement in a rabbit model.Methods On the 10th day after half-liver single 40 Gy X-ray irradiation,MR imaging before and after SPIO administration and pathologic study of 12 adult rabbits were performed.Results On the 10th post-irradiation day,TSE T_2 WI before SPIO enhancement,the irradiated liver of two rabbits showed relatively higher signal, and 1 showed slightly lower signal.With SPIO enhancement,the irradiated livers of 9 rabbits were found to be abnormal,manifesting as higher or slightly higher areas on multiple MR imaging sequences,especially the TFE T_1 WI sequence.Histological specimen with HE stain under light microscopy revealed occlusive injury of central veins(veno-occlusive disease,VOD)in each irradiated liver to some extent.Electron microscopy investigation of the irradiated liver disclosed intracellular edema,fibrin deposition,and widening of the Disse-space.Conclusion The early pathologic feature of the irradiated liver is occlusive injury of the central vein.MR imaging with SPIO enhancement is effective to valuate the early irradiation-induced liver injury.