The role of contrast-enhanced ultrasound in the detection of focal liver leasions

Abstract

IntroductionOver the last decade, the therapeutic approach for treating focal liver malignancies, including both hepatocellular carcinoma (HCC) and metastatic lesions, has changed dramatically, particularly due to the proliferation of new treatment strategies. These have included percutaneous ablative therapies such as percutaneous ethanol injection (PEI), thermal therapies such as radiofrequency (RF), laser, and microwaves, as well as angiographic therapies such as segmental chemoembolization and hypoxic perfusion, and orthotopic liver transplantation (OLT). Furthermore, at the same time, there has been a general greater acceptance of previously characterized, more standard treatment modalities such as surgical resection and systemic chemotherapy. Given this wide range of potential therapeutic options, a main aim of current medical management of focal liver cancer is to tailor therapy for every patient by selecting the therapeutic modality which will ideally provide the highest success rate, fewest risks and lowest costs for each given situation. However, in order to provide this level of optimized, individualized care, accurate detection of neoplastic lesions by imaging modalities including ultrasound (US), computed tomography (CT), and magnetic resonance imaging (MRI) is mandatory.Worldwide, US is the most widely available imaging modality for the screening of liver pathology, and has furthermore functioned as the mainstay for screening efforts for the detection of small incidental hepatomas in high-risk patients. Nevertheless, the limitations of conventional gray-scale B-mode US for the detection of focal liver lesions have been well documented [1,2]. Color Doppler and power Doppler increased the sensitivity for hepatic lesion detection compared to grayscale US, but they did not allow levels of sensitivity comparable to those of contrast enhanced axial imaging (CT and MRI). Two breakthroughs in US, harmonic imaging and the development of second-generation contrast agents, have recently been described and have demonstrated the potential to dramatically broaden the scope of US diagnosis of hepatic lesions. This paper will review the prior state of the art for the sonographic detection of the two most common forms of focal liver neoplasia (HCC and metastases), and illustrate the potential of the newer techniques for improving the sensitivity of US . Historical review of conventional ultrasonography Hepatocellular carcinomasThe detection rate of HCC using US is related to the size, location, and echotexture of the lesions, as well as to both the US technology employed and operator experience. Nevertheless, due to successive technologic improvements, there has been a trend toward detecting ever smaller lesions. Given a wide range of techniques and technology, the reported detection rate of HCCs measuring less than 2 cm in diameter has been variable, ranging from 46% to 95% [1, 3, 4], with accurate detection of 82-93% of HCCs measuring between 2 and 3 cm. For HCCs smaller than 1 cm, US is reported to have a detecti...

Detection of focal liver lesions in cirrhotic liver using contrast-enhanced ultrasound

“…Many studies have confirmed the improvement in accuracy of CEUS in diagnosing MLC [40,51,52] . CEUS also improved the detection of miliary metastases (0.5-1 cm) [53] . In the arterial phase, hypovascular metastases appear as hypo-enhanced lesions, with a typical rim enhancement of varying size ("halo sign", "rim sign"), whereas hypervascular metastases appear as hyper-enhanced and homogeneous lesions [28] .…”

How useful is preoperative imaging for tumor, node, metastasis (TNM) staging of gastric cancer? A meta-analysis

“…AUS has difficulty in evaluating the wall of the gastric fundus and greater curvature, as well as lymphatic spread [7,8]. It is also highly dependent on patient body habitus and the operator [9]. Traditional single detector scanners (S-CT) are limited by large section thickness, low image resolution, and slow scanning causing respiratory motion artifacts, and they are unable to provide multi-planar reformations [10,11].…”

Hepatic metastases of hemangiopericytoma: contrast-enhanced MRI, contrast-enhanced ultrasonography and angiography findings

“…Contrastenhanced MRI with Gd-BOPTA or ferumoxides and US with BR1 can be used for supplementary liver imaging. US with BR1 is an upcoming way to illustrate liver lesions in various vascular phases, and has some advantages over other modalities for imaging of liver metastases, such as convenience, the probability of fewer side-effects, no exposure to radiation, and no risk of missing the optimal time for observation [9] .…”

“…US was performed with BR1 (Sonovue, Bracco, Milan, Italy) [9] . Unenhanced US scan of the liver showed multiple hypoechoic lesions ( Fig.…”

“…Recently, contrastenhanced MRI has emerged as a valuable non-invasive technique which provides a rich analysis of the regional vascular properties of a tumour [7,8] . Ultrasonography (US) with the use of second-generation contrast agent has the potential to increase the detection of hypervascular tumours [9] . We describe the CT, contrast-enhanced MRI, US with second-generation contrast agent, and angiography findings in a patient with hepatic metastases of hemangiopericytoma.…”