Semiquantitative characterization of perfusion with contrast-enhanced ultrasound and perfusion analysis – comparison of hepatocellular carcinoma (HCC) and focal nodular hyperplasia (FNH)

Aims: Several imaging modalities are available for the detection of focal liver lesions. Due to the therapeutic implications differentiation between focal nodular hyperplasia (FNH) and hepatocellular carcinoma (HCC) is important. At the moment, there is only poor specificity of HCC-detection in tumors smaller than two centimeters. Focal nodular hyperplasia is a common benign tumor in normally younger female patients. Particularly in smaller FNH lesions the prescence of a central artery and the typical scarring, centrifugal progression of enhancement is missing.

Therefore, efforts have to be made to optimize the distinction between these two hypervascular tumor entities.

Aims: The aim of our study was the comparison between the particular perfusion patterns of hepatocellular carcinoma and focal nodular hyperplasia using a specific quantification software.

Methods: We evaluated 25 patients with proven hepatocellular carcinoma and 24 patients with proven focal nodular hyperplasia, who underwent dynamic contrast-enhanced ultrasound (CEUS) using a second generation contrast agent (SonoVue®, Bracco, Germany). Retrospectively, we applied the quantification software Qontrast® (Bracco, Milan, Italy) to obtain contrast-enhanced sonographic perfusion maps for each lesion.

Results: There was a noticeable difference in the perfusion parameters peak (PEAK), time-to-peak (TTP), and regional blood volume (RBV) between the both entities. Focal nodular hyperplasia showed a significantly shorter time-to-peak (p < 0,001) and a significantly lower regional blood volume (p < 0,05) than HCC lesions, whereas the trend to higher peak values in FNH was not significant.

Conclusion: Tumor-specific vascularization pattern in CEUS has a high diagnostic impact diagnostic accuracy of CEUS for the differenzial diagnosis of hepatic tumors in clinical practice. Rapid washout in contrast-enhanced sonography characterizes metastases, whereas HCCs show variable, often slow, washout if at all.

Our results suggest a faster contrast enhancement in FNH lesions than in HCC tumors. However, the peak value of perfusion showed no significant difference. In summary, comparing these tumor entities our data show only slight differences in arterial perfusion, a specific perfusion pattern useful in differentiation was not detectable. Therefore sonographic differenzial diagnosis in small lesions still remains difficult and has to be based on further investigations.