Recently, Gadoxetic acid (Gd-EOB-DTPA; Primovist®; Bayer Schering Pharma), a tissue-specific contrast material, has been used for clinical MR imaging. This agent is a biphasic hepatobiliary contrast agent because it behaves as both an extracellular and a hepatocyte-specifi c agent as it undergoes both renal and biliary excretion. Up to 50% of the injected dose is taken up into normal hepatocytes due to the presence of the lipophilic ethoxybenzyl group in its chemical structure. As such, dynamic imaging can be performed using this agent for the evaluation of hemodynamic perfusion or status and for hepatobiliary phase imaging (10 to 20 minutes after injection) for the evaluation of functional status. Compared to extracellular contrast materials, Gadoxetic acid-enhanced magnetic resonance imaging (MRI) provides comparable arterial enhancement and prominent venous washout of hepatocellular carcinoma (HCC) during dynamic imaging. Additional hepatobiliary phase images are useful for the detection of small lesions that are not readily visible during dynamic imaging. Current evidence and experience suggest that Gadoxetic acid-enhanced MRI will improve the accuracy of HCC imaging diagnosis by allowing better characterization of hypovascular lesions and better differentiation of small arterial enhancing lesions as well as by providing improved preoperative staging accuracy. Therefore, with the aid of Gadoxetic acid-enhanced MRI, very early HCC will be more commonly diagnosed, with patient treatment occurring in earlier stages of the disease.
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