State-of-the-art ultrasonography of hepatocellular carcinoma

Diagnosis of hepatocellular carcinoma: newer radiological tools

With the recent dramatic advances in diagnostic modalities, the diagnosis of hepatocellular carcinoma (HCC) is primarily based on imaging. Ultrasound (US) plays a crucial role in HCC surveillance. Dynamic multiphasic multidetector-row CT (MDCT) and magnetic resonance imaging (MRI) are the standard diagnostic methods for the noninvasive diagnosis of HCC, which can be made based on hemodynamic features (arterial enhancement and delayed washout). The technical development of MDCT and MRI has made possible the fast scanning with better image quality and resolution, which enables an accurate CT hemodynamic evaluation of hepatocellular tumor, as well as the application of perfusion CT and MRI in clinical practice. Perfusion CT and MRI can measure perfusion parameters of tumor quantitatively and can be used for treatment response assessment to anti-vascular agents. Besides assessing the hemodynamic or perfusion features of HCC, new advances in MRI can provide a cellular information of HCC. Liver-specific hepatobiliary contrast agents, such as gadoxetic acid, give information regarding hepatocellular function or defect of the lesion, which improves lesion detection and characterization. Diffusion-weighted imaging (DWI) of the liver provides cellular information of HCC and also has broadened its role in lesion detection, lesion characterization, and treatment response assessment to chemotherapeutic agents. In this article, we provide an overview of the state-of-the art imaging techniques of the liver and their clinical role in management of HCC.

Posterior acoustic enhancement in hepatocellular carcinoma

OBJECTIVES

The purpose of this study was to assess sonographic appearances of hepatocellular carcinoma with particular attention to posterior acoustic effects.

METHODS

We performed an Institutional Review Board-approved retrospective review of patients with hepatocellular carcinoma who had undergone sonographically guided procedures in our department between 2001 and 2010. A total of 247 masses thought to represent hepatocellular carcinoma were identified; 27 were excluded because of prior angioembolization (altering the sonographic appearance), alternate histologic diagnoses, and incomplete patient information or imaging. Ultimately, 220 masses in 185 patients (138 men and 47 women; average age, 59.1 years) constituted the study population. Preprocedure sonograms were reviewed in consensus by 3 abdominal radiologists; the liver echo texture, lesion echogenicity, and posterior acoustic effect were rated and correlated with patient data.

RESULTS

The average mass size was 3.1 cm (range, 0.7-17 cm). In total, 84.1% of the masses (n = 185) arose in abnormally echogenic/attenuating livers; 54.1% of the masses (n = 119) were predominantly hypoechoic, 23.2% (n = 51) isoechoic, and 22.7% (n = 50) hyperechoic. Target-type morphologic characteristics were noted in 41 masses. Many masses (52.7% [n = 116]) had no specific posterior acoustic effect, but nearly half (46.4%) had either mild (n = 64) or marked (n = 38) posterior acoustic enhancement. The remaining masses (0.9% [n = 2]) had posterior shadowing. Posterior acoustic enhancement was most common among hyperechoic masses (62% with posterior acoustic enhancement), target-type masses (63%), and masses larger than 5 cm (81.5%).

CONCLUSIONS

Posterior acoustic enhancement is present to some degree in almost half of hepatocellular carcinomas, which may relate to the tissue characteristics of the tumor or the cirrhotic liver itself. Attention to this finding, including scanning without spatial compounding, is recommended during sonographic screening for hepatocellular carcinoma in the growing population of patients with liver disease.

Focal liver lesions: role of contrast-enhanced ultrasound

The introduction of microbubble contrast agents and the development of contrast-specific techniques have opened new possibilities in liver imaging. Initially, only intermittent imaging with Doppler detection was available. Second-generation contrast agents and low mechanical index real-time scanning techniques are decisive advances that enable convenient liver examinations with high sensitivity and specificity. Hepatic lesions usually show typical perfusion and enhancement patterns through the various contrast phases, which help their characterization. Several published studies and the daily clinical routine show that, as opposed to conventional ultrasound (US), contrast-enhanced US can substantially improve detection and differentiation of focal liver lesions. Today, contrast-enhanced US is the dynamic imaging modality of choice for differentiation of focal liver lesions. Contrast uptake patterns of the most relevant liver lesions, as well as important clinical indications are presented and discussed.