Ultrasonography, Computed Tomography and Magnetic Resonance Imaging of Hepatocellular Carcinoma: Toward Improved Treatment Decisions

Abstract

Detection, characterization, staging, and treatment monitoring are major roles in imaging diagnosis in liver cancers. Contrast-enhanced ultrasonography (CEUS) using microbubble contrast agents has expanded the role of US in the detection and diagnosis of liver nodules in patients at high risk of hepatocellular carcinoma (HCC). CEUS provides an accurate differentiation between benign and malignant liver nodules, which is critical for adequate management of HCC and is also useful for guidance of percutaneous local therapy of HCC and postprocedure monitoring of the therapeutic response. The technology of multidetector-row computed tomography (MDCT) has increased spatial and temporal resolutions of computed tomography (CT). It has made possible a more precise evaluation of the hemodynamics of liver tumor, and the diagnostic accuracy of dynamic MDCT has improved. Perfusion CT can measure tissue perfusion parameters quantitatively and can assess segmental hepatic function. Dynamic MDCT with high spatial and temporal resolution enables us to reconstruct 3- and 4-dimensional imaging, which is very useful for pretreatment evaluation. Dual-energy CT makes possible the differentiation of materials and tissues in images obtained based on the differences in iodine and water densities. Monochromatic images, which can be reconstructed by dual-energy CT data, provide some improvement in contrast and show a higher contrast-to-noise ratio for hypervascular HCCs. Dynamic magnetic resonance imaging with fast imaging sequence of 3-dimensional Fourier transformation T₁-weighted gradient echo and nonspecific contrast medium can show high detection sensitivity of hypervascular HCC. However, the hepatic tissue-specific contrast medium, gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid, has become an essential contrast medium for liver imaging because of its higher diagnostic ability. It may replace CT during hepatic arteriography and during arterioportography.

Ultrasonography Fusion Imaging System Increases the Chance of Radiofrequency Ablation for Hepatocellular Carcinoma with Poor Conspicuity on Conventional Ultrasonography

“…In recent years, the US fusion imaging system for the guidance of RFA has become available [8,17,20,21]. In the US fusion imaging system, any cross-sectional multiplanar reconstruction images of the volume data of CT or MRI are synchronously displayed side-by-side with the real-time US images, in accordance with the movement of the probe [15,16,17,20].…”

“…CEUS with Sonazoid is reported to be useful for the diagnosis and treatment of HCC [8,11,29,30]. Sonazoid provides a fine vascular image of hepatic tumors in vascular phase, and is very sensitive in detecting an early stain of HCC.…”

“…Since second-generation contrast medium for ultrasonography (US) including Sonazoid (Daiichi-sankyo, Tokyo, Japan) and gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA; Primovist, Bayer Healthcare, Osaka, Japan), a liver-specific magnetic resonance (MR) contrast agent, became available, imaging diagnosis of HCC has dramatically advanced [8,9,10,11,12,13,14]. As a result, the diagnosis of HCC has come to be made at an earlier stage.…”

Hepatocellular Carcinoma: Current Concepts in Diagnosis, Staging and Treatment

“…In Asia it is therefore recommended as a decisional tool concerning hypovascular lesions <1 cm in size [16]. Sonazoid-enhanced ultrasound was even more sensitive in the detection of focal liver lesions than CT [17]. …”

Contrast-enhanced ultrasound-guided radiofrequency ablation in inconspicuous hepatocellular carcinoma on B-mode ultrasound

“…It enhances the blood and consequently improves the signal-to-noise ratio in US. Contrast-enhanced ultrasound (CEUS) with SonoVue showed improved diagnostic sensitivity and detectability for small and inconspicuous HCCs, compared with conventional B-mode US (10,11). Moreover, detection of hypervascularity in early HCC was significantly improved with CEUS compared with dynamic studies such as CT or MRI (12).…”