Accurate diagnosis of hepatocellular carcinoma(HCC) in the early stage is vital for its treatment.Contrast-enhanced dynamic magnetic resonance imaging(MRI) performed in the presence of extracellular contrast agents such as gadolinium chelates is considered as a useful approach for detecting and characterizing focal liver lesions.However,the sensitivity and specificity of conventional MRI contrast agents are far from satisfaction for the detection and characterization of benign and malignant focal liver lesions in the early stage.The novel molecular contrast agents special for liver with relatively longer metabolic time and stable contrast effect in liver tissue are highly desired.The development of nanotechnology provides an unprecedented opportunity for the diagnostic detection rate of HCC and cell-surface receptor-targeted nanotechnology improves the specificity of the detection of focal liver lesions.In order to maximize lesion detection and characterization,novel gadolinium chelates loaded nanovectors including the solid lipid nanoparticles,nanocomplexes and polymeric nanoparticles have been used as biocompatible molecular MRI contrast agent.In this review,the characterization and the advantages/disadvantages of these Gd-loaded novel nanovectors used as molecular MRI contrast agents were discussed.Furthermore,liver target nanovectors aimed at improving the diagnostic accuracy of liver MRI by targeting additional features of focal liver lesions were highlighted.
