Ultrasound of focal liver lesions

This paper gives a comprehensive overview of ultrasound of focal liver lesions. Technical aspects such as examination technique and the use of Doppler modes as well as recent developments such as tissue harmonic imaging and microbubble contrast agents are discussed. The clinical significance and sonographic features of various liver lesions such as haemangioma, focal nodular hyperplasia, adenoma, regenerative nodule, metastasis, hepatocellular carcinoma and various types of focal infections are described. With the exception of cysts and typical haemangiomas, definitive characterisation of a liver lesion is often not possible on conventional ultrasound. This situation has changed with the recent advent of ultrasound contrast agents, which permit definitive diagnosis of most lesions. Contrast-enhanced sonography using recently developed contrast-specific imaging modes dramatically extends the role of liver ultrasound by improving its specificity in the detection and characterisation of focal lesions to rival CT and MRI.     

Incidental focal solid liver lesions: diagnostic performance of contrast-enhanced ultrasound and MR imaging

Objective  

To prospectively assess the diagnostic performance of contrast-enhanced ultrasound (CEUS) and MR imaging in incidental solid focal liver lesions not characterised on ultrasound.     

Routine MR imaging protocol with breath-hold fast scans: diagnostic efficacy for focal liver lesions

PURPOSE: To qualitatively and quantitatively evaluate the diagnostic efficacy of the breath-hold magnetic resonance (MR) imaging sequences in widespread clinical use for detection and characterization of focal hepatic lesions. MATERIALS AND METHODS: Fifty patients with 143 lesions [57 hepatocellular carcinomas (HCC), 10 borderline lesions, 18 metastatic tumors, 21 hemangiomas, and 37 cysts] underwent single-shot fast spin echo (SSFSE), fast spin echo (FSE), and gadolinium-enhanced dynamic fast spoiled gradient-recalled acquisition in steady state (FSPGR) breath-hold MR imaging of the liver. Alternative free receiver operating characteristic (AFROC) analysis was performed to independently and prospectively assess each sequence. RESULTS: For solid lesions, dynamic FSPGR allowed the most sensitive lesion detection and produced the highest lesion conspicuity and lesion-liver contrast-to-noise ratio (CNR). For non-solid benign lesions, SSFSE and FSE produced better results than dynamic FSPGR. SSFSE allowed the most sensitive detection and produced the best lesion conspicuity and lesion-liver CNR. CONCLUSION: SSFSE and dynamic FSPGR comprise the optimal imaging protocol for breath-hold MR assessment of focal hepatic lesions. This combination of sequences allows acquisition of critical diagnostic information about both inherent T2 and T1 lesion contrast and lesion vascularity.     

Clinical value of MRI liver-specific contrast agents: a tailored examination for a confident non-invasive diagnosis of focal liver lesions

Screening of the liver for hepatic lesion detection and characterization is usually performed with either ultrasound or CT. However, both techniques are suboptimal for liver lesion characterization and magnetic resonance (MR) imaging has emerged as the preferred radiological investigation. In addition to unenhanced MR imaging techniques, contrast-enhanced MR imaging can demonstrate tissue-specific physiological information, thereby facilitating liver lesion characterization. Currently, the classes of contrast agents available for MR imaging of the liver include non-tissue-specific extracellular gadolinium chelates and tissue-specific hepatobiliary or reticuloendothelial agents. In this review, we describe the MR features of the more common focal hepatic lesions, as well as appropriate imaging protocols. A special emphasis is placed on the clinical use of non-specific and liver-specific contrast agents for differentiation of focal liver lesions. This may aid in the accurate diagnostic workup of patients in order to avoid invasive procedures, such as biopsy, for lesion characterization. A diagnostic strategy that considers the clinical situation is also presented.     

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

Patients with liver cirrhosis are at increased risk of hepatocellular carcinoma (HCC). Conventional or baseline ultrasound (BUS) is often used as the first-line tool for HCC surveillance or detection, but the accuracy of BUS in HCC detection or differentiation from other focal liver lesions (FLLs) is limited. Contrast-enhanced ultrasound (CEUS) represents a recent revolution in the field of ultrasonography and it has become increasingly important in the detection and evaluation of FLLs. In CEUS, HCC typically exhibits arterial hyper-enhancement and portal-venous washout represented by hypo-enhanced lesions in the portal venous and late phases. The detection rate of HCC was significantly higher with CEUS compared with BUS. Even regenerative or some dysplastic nodules may exhibit arterial hyper-enhancement as they are differentiated from HCC by its iso-enhancing pattern in portal and late phases. The contrast-enhancement patterns of other different types of benign and malignant FLLs, as well as their detection rates with CEUS, were also discussed.     

Real-time contrast-enhanced ultrasound imaging of focal liver lesions in fatty liver

PurposeThe objective of this study was to investigate the contrast-enhanced ultrasound (CEUS) imaging features of focal liver lesions (FLLs) in fatty liver.MethodOne hundred FLLs in 98 patients with fatty liver were evaluated with real-time CEUS.ResultsAll malignant FLLs showed hyperenhancement in arterial phase and contrast washout in portal and late phases. Among the FLLs, 3.3% of hemangiomas, 12.5% of focal nodular hyperplasias (FNHs), and 2.5% of focal fatty sparing lesions showed contrast washout in the late phase. The sensitivity and specificity for the characterization of hepatocellular carcinoma, metastasis, hemangioma, FNH, and focal fatty sparing lesions were 100% and 95.6%, 60% and 100%, 93.3% and 98.6%, 87.5% and 97.8%, and 92.6% and 100%, respectively.ConclusionsCorrect characterization of FLLs in fatty liver by CEUS is possible based on their typical enhancement patterns.     

Nuclear medical differentiation of focal lesions of the liver

Radio-colloid scintigraphy, hepatobiliary scintigraphy and blood pool scanning with tagged red blood cells are well-established methods of nuclear medicine for the differential diagnosis of hepatic lesions. Hepatic hemangiomas and focal nodular hyperplasia can be differentiated in over 90% of cases. The sensitivity of single-photon emission computer tomography (SPECT) in the detection of liver masses greater than 2 cm diameter is 92%-98%.     

Critical analysis of the diagnostic imaging of focal hepatic lesions]

The aim of this paper is to evaluate the number and type of consecutive initial diagnoses of focal hepatic lesions obtained by abdominal US and CT. The diagnoses were coded according to the Index for Radiological Diagnoses (ACR). From January 1990 through April 1991, US and CT diagnosed focal hepatic lesion in 16.4% and 9.1% of cases, respectively. A lower number of focal hepatic lesions was diagnosed by CT, which however was more accurate as to the nature of the lesion itself. This is due to the fact that CT is often used to stage hepatic neoplasms already confirmed by US-guided fine-needle biopsy (FBN). The correlation between the initial diagnosis and actual clinical status demonstrates a high rate of occasional findings, especially with US. The rate of questionable diagnoses relative to primary or secondary malignancies was very high. This could be explained by caution in making a severe diagnosis, by awareness of the limits of macroscopic diagnostic techniques and by the immediate availability of US-guided FNB. In conclusion, the coding of consecutive initial diagnoses, by US and CT, could contribute to a practical evaluation of diagnostic imaging techniques, especially when correlated with the respective anamnestic and clinical data. Further studies are necessary to confirm this hypothesis.     

MnDPDP enhanced magnetic resonance imaging of focal liver lesions

Mangafodipir trisodium (MnDPDP) is a contrast agent for use in magnetic resonance imaging (MRI) of the liver. The agent is taken up by normal hepatocytes resulting in increased signal on T1-weighted imaging, and is excreted in the biliary system. Hepatocyte-containing liver neoplasms such as hepatomas or focal nodular hyperplasia (FNH), take up MnDPDP and demonstrate varying degrees of enhancement. Metastatic liver deposits and primary liver tumours of non-hepatocyte origin do not typically enhance with MnDPDP thus increasing their conspicuity compared with pre-contrast T1-weighted images. Metastases may demonstrate rim enhancement particularly on delayed imaging at 24 h, which can increase their conspicuity, thus allowing better visualization of small lesions. Functional biliary obstruction due to liver metastases can also result in wedge shaped areas of parenchymal enhancement.The MRI features of various focal liver after continuance with lesions following MnDPDP are discussed and illustrated including primary lesions such as hepatoma and secondary metastases.     

Characterization of hypoechoic focal hepatic lesions in patients with fatty liver: diagnostic performance and confidence of contrast-enhanced ultrasound

The objective of this study was to assess the diagnostic performance of contrast-enhanced ultrasound (CEUS) to characterize hypoechoic focal hepatic lesions (HFHL) in fatty liver (FL). A study group of 105 patients with FL and 105 HFHLs (52 malignant and 53 benign) underwent CEUS after SonoVue administration. Two blinded readers independently reviewed baseline ultrasound (US) and CEUS scans and classified each lesion as malignant or benign on a five-point scale of confidence, and recorded whether further imaging work-up was needed. Sensitivity, specificity, areas under the receiver operating characteristic (ROC) curve (A (z)), and interobserver agreement were calculated. We observed that the diagnostic confidence improved after reviewing CEUS scans for both readers (A (z)=0.706 and 0.999 and A (z)=0.665 and 0.990 at baseline US and CEUS, respectively; p<0.0001). Inter-reader agreement increased (weighted k=0.748 at baseline US vs. 0.882 at CEUS). For both readers, after CEUS, the occurrence of correctly characterized lesions increased (from 27/105 [27.5%] to 94/105 [89.5%], and from 19/105 [18.1%] to 93/105 [88.6%], respectively; p<0.0001) and the need for further imaging decreased (from 93/105 [88.6%] to 26/105 [24.8%], and from 96/105 [91.4%] to 40/105 [38.1%], respectively; p<0.0001). We conclude that CEUS improves the diagnostic performance of radiologists in the characterization of HFHLs in FL and reduces the need for further imaging work-up.     

Benign focal liver lesions: discrimination from malignant mimickers

Focal lesions of the liver often have various imaging characteristics which may be interpreted as either benign or malignant. Understanding the underlying pathophysiology of these liver lesions may lead to characteristic imaging manifestations, which direct the radiologist to the diagnosis. Benign lesions include congenital hepatic cyst, autosomal dominant polycystic disease, hemangioma, focal nodular hyperplasia (FNH), hepatic adenoma, inflammatory pseudotumor, peliosis hepatis, focal fatty infiltration, hamartoma, and infectious processes such as hepatic abscess, echinococcal cyst, and candidiasis. Characteristic imaging features, clinical symptoms, and treatment/prognosis will be discussed. Emphasis will be placed on key reliable features of each disease to develop a method of discriminating these lesions from other benign and malignant disorders.     

Clinical significance of hyperechogenic focal lesions of the cirrhotic liver

A review was made of the ultrasonographic (US) examinations performed over the period 1981-1986; 27 cirrhotic patients with hyperechoic liver lesions were identified, whose diagnoses had been made by means of either US-guided percutaneous biopsy, or laparoscopy, or autopsy. In 24 patients hepatocellular carcinomas nodules (HCC) were found, associated with cirrhosis, while in 3 cases only cirrhosis was seen. In the above mentioned 3 cases, a 2-year US follow-up showed no variation in the size of the nodules. These data confirm the importance of US in the screening of risk HCC patients, and point out that--however small--hyperechoic lesions in a cirrhotic liver suggest the cancerization of the substanding cirrhosis.     

Role of contrast enhanced ultrasound in characterization of focal liver lesions

Aim

The purpose of the study was to describe the enhancement patterns of focal liver lesions (FLLs) on contrast enhanced sonography (CEUS), assessing the potential of this technique for characterizing the lesions and to compare its diagnostic accuracy with conventional baseline sonography including color Doppler.

Materials and methods

Between August 2009 and July 2010, 50 patients with FLLs underwent gray scale sonography, color Doppler and CEUS. The enhancement patterns of these FLL’s were analyzed throughout the arterial phase, the portal venous phase and the extended portal venous phase (the late parenchymal phase). The final diagnosis was established on the basis of histopathologic examination or CT/MRI imaging.

Results

Out of these 50 FLLs, 33 were malignant (4 hepatocellular carcinoma and 29 metastasis) and 17 were benign (5 hemangioma, 5 abscess, 2 cyst and 1 each of FNH, focal fat sparing area, focal fatty infiltration, adenoma and benign/granulomatous lesion). The enhancement patterns after injecting microbubble contrast agent allowed characterization of FLLs. The malignant lesions showed intratumoral and/or peritumoral vascularity during the arterial phase and perfusion defect during the late parenchymal phase. Contrast enhanced sonography improved sensitivity in detecting malignancy (CEUS vs. baseline sonography, 100% vs. 81.8%).

Conclusion

CEUS improves detection and characterization of FLLs. It should be used as problem solving tool in cases where conventional gray scale and color Doppler sonography are non-diagnostic.