Perfusion-weighted MRI in evaluating the intranodular hemodynamic characteristics of dysplastic nodules and hepatocellular carcinomas in an experimental rat model.

PURPOSE To investigate the value of perfusion-weighted MRI in the evaluation of the intranodular hemodynamic characteristics of dysplastic nodules (DNs) and hepatocellular carcinomas (HCCs) in an experimental rat model. MATERIALS AND METHODS A total of 40 rats with chemically-induced DNs and HCCs were investigated. Single-slice gadolinium-enhanced perfusion-weighted MRI was performed to evaluate the nodules. Time to peak (Tp), maximal relative signal enhancement (REmax), and the initial slope of signal intensity (SI) vs. time curves of the nodules and cirrhotic liver were evaluated. Nodules precisely corresponding to MRI were examined histologically. Paired Student's t-tests were used to compare the difference between nodules and cirrhotic liver. RESULTS A total of 20 HCCs and 14 DNs were evaluated. HCCs showed a significantly higher REmax, shorter Tp, and higher slope than adjacent cirrhotic liver. The REmax and slope of DNs were significantly lower than adjacent cirrhotic liver parenchyma. Although the Tp of DNs was delayed two to three seconds compared to adjacent cirrhotic liver, there was no significant difference between them. CONCLUSION Perfusion-weighted MRI detected the intranodular hemodynamic characteristics of DNs and HCCs in an experimental rat model. DNs were hypovascular compared to cirrhotic liver, while HCCs were markedly hypervascular.