Imaging of hepatocellular carcinoma: qualitative and quantitative analysis of postvascular phase contrast-enhanced ultrasonography with sonazoid. Comparison with superparamagnetic iron oxide magnetic resonance images.

PURPOSE

To evaluate the usefulness of vascular phase images of contrast-enhanced ultrasonography (CE-US) with Sonazoid for hepatocellular carcinomas (HCCs), a retrospective, comparative study was conducted of images of HCCs obtained by CE-US and superparamagnetic iron oxide (SPIO) magnetic resonance imaging (MRI) and evaluated qualitatively and quantitatively.

METHODS

Seventy-seven patients with 88 HCCs who received CE-US and SPIO-MRI were reviewed. The ratio of the echogenicity of the tumor and nontumor areas was calculated with postvascular phase CE-US (postvascular phase ratio). The ratio of the intensity of the nontumor to tumor areas on SPIO-enhanced MRI (SPIO intensity index) was also calculated. The Pearson correlations were calculated for all values between the postvascular phase ratio and SPIO intensity index for quantitative comparison. These images were also compared qualitatively for the detection rate of the tumors.

RESULTS

The sensitivities of CE-US and SPIO-MRI in detecting tumors were 98 and 95%, respectively (nonsignificant, chi(2) test). The postvascular phase ratio correlated with the SPIO intensity index for HCCs (Pearson r = 0.803, p < 0.05). The image conformity of the result from the liver parenchymal phase CE-US and SPIO-MRI was 92%. Dedifferentiation spots of nodule-in-nodule HCCs were detected in 4 (80%) of 5 on postvascular phase images of CE-US, and in 2 (40%) of 5 on SPIO-MRI (nonsignificant, chi(2) test).

CONCLUSIONS

Postvascular phase images of CE-US with Sonazoid appear promising as an alternative to SPIO-enhanced MRI. Further study cases are needed to confirm the usefulness of postvascular phase images of CE-US compared to SPIO-MRI for the detection of dedifferentiation foci in hepatic tumors.