Role of contrast enhanced ultrasonography in the assessment of hepatic metastases: A review

Contrast enhanced ultrasonography (CEUS) has improved both the detection and characterization of focal liver lesions. It is now possible to evaluate in real time the perfusion of focal liver lesions in the arterial, portal and late contrast phases, and thus to characterize focal liver lesions with high diagnostic accuracy. As a result, CEUS has taken a central diagnostic role in the evaluation of focal liver lesions that are indeterminate upon computed tomography (CT) and magnetic resonance imaging. The combined use of second generation contrast agents and low mechanical index techniques is essential for the detection of liver metastases, and it now allows the examination of the entire liver in both the portal and late phases. Several studies have shown that using CEUS instead of conventional ultrasonography without contrast agents significantly improves sensitivity in detection of liver metastases. Furthermore, the detection rate with CEUS seems to be similar to that of CT. This review describes the clinical role of CEUS in detecting liver metastases, including details about examination techniques, features of metastases observed with CEUS, and clinical results and guidelines.     

Contrast-enhanced ultrasonography to detect liver metastases

Background/aims The advent of contrast-enhanced ultrasound (CEUS) has called into question the efficacy of standard ultrasonographic techniques. In this study, we evaluated B-mode and color-duplex imaging and CEUS in the detection of liver metastases, using intraoperative and histological findings as a reference. Materials and methods Before laparotomy, 108 patients suspected of having liver metastases were prospectively examined with B-mode and color-duplex imaging, followed by contrast-enhanced ultrasound (2.4 ml SonoVue). Patients with unresectable tumors (n=8) were excluded from the analysis. The sonographic diagnosis in the remaining 100 patients was compared to the intraoperative and histological findings. Results/findings CEUS improved the sensitivity for detecting liver lesions from 56.3% (B-mode) to 83.8% (CEUS) (p=0.004). In particular, the contrast agent led to an improvement in ultrasonographic detection in the following cases: nodular metastases smaller than one centimeter; after adjuvant chemotherapy; for tumors near the surface of the liver; and for lesions situated around the ligamentum teres. Interpretation/conclusions CEUS provides significant improvement in the detection of liver metastases, and should therefore, be performed routinely in the surveillance of cancer patients. Dr. Konopke and Dr. Kersting contributed equally to this work.     

Contrast‐enhanced ultrasound in the preoperative,intraoperative and postoperative assessment of liver lesions

The use of contrast agents (CA) with liver ultrasound (US) has gained recently an established role for the diagnosis of various hepatic diseases due to their safety, high versatility and low costs (contrast‐enhanced ultrasound: CEUS). The purpose of this review is to provide a state‐of‐the‐art summary of the available evidence for their use in the characterization of focal liver lesions. A published work search was conducted for all preclinical and clinical studies involving CA on hepatic US imaging. CEUS increases the sensitivity for lesion detection and the specificity to differentiate between benign and malignant diseases due to the enhanced visualization of the tumor microcirculation. Results achieved seem at least equivalent to those of spiral computed tomography or magnetic resonance imaging. The association of CA with intraoperative ultrasound has changed the surgical approach in 25% of patients and guarantees complete ablations by a single session in most of them. CEUS provides detailed information about tumor vasculature, improves the preoperative characterization and therefore the therapeutic strategy, and can evaluate the intraoperative completeness of the ablation.     

Contrast‐enhanced ultrasound for quantification of tissue perfusion in humans

Contrast‐enhanced ultrasound is an imaging technique that can be used to quantify microvascular blood volume and blood flow of vital organs in humans. It relies on the use of microbubble contrast agents and ultrasound‐based imaging of microbubbles. Over the past decades, both ultrasound contrast agents and experimental techniques to image them have rapidly improved, as did experience among investigators and clinicians. However, these improvements have not yet resulted in uniform guidelines for CEUS when it comes to quantification of tissue perfusion in humans, preventing its uniform and widespread use in research settings. The objective of this review is to provide a methodological overview of CEUS and its development, the influences of hardware and software settings, type and dosage of ultrasound contrast agent, and method of analysis on CEUS‐derived perfusion data. Furthermore, we will discuss organ‐specific imaging challenges, advantages, and limitations of CEUS.     

Imaging evaluation of the liver in oncology patients: A comparison of techniques

The liver is commonly affected by metastatic disease. Therefore, it is essential to detect and characterize liver metastases, assuming that patient management and prognosis rely on it. The imaging techniques that allow non-invasive assessment of liver metastases include ultrasonography, computed tomography (CT), magnetic resonance imaging (MRI), positron emission tomography (PET)/CT, and PET/MRI. In this paper, we review the imaging findings of liver metastases, focusing on each imaging modality’s advantages and potential limitations. We also assess the importance of different imaging modalities for the management, follow-up, and therapy response of liver metastases. To date, both CT and MRI are the most appropriate imaging methods for initial lesion detection, follow-up, and assessment of treatment response. Multiparametric MRI is frequently used as a problem-solving technique for liver lesions and has evolved substantially over the past decade, including hardware and software developments and specific intravenous contrast agents. Several studies have shown that MRI performs better in small-sized metastases and moderate to severe liver steatosis cases. Although state-of-the-art MRI shows a greater sensitivity for detecting and characterizing liver metastases, CT remains the chosen method. We also present the controversial subject of the "economic implication" to use CT over MRI.     

Contrast-enhanced ultrasound in differentiating malignant from benign portal vein thrombosis in hepatocellular carcinoma

Portal vein thrombosis (PVT) may occur in liver cirrhosis patients. Malignant PVT is a common complication in cirrhotic patients with concomitant hepatocellular carcinoma (HCC) and, in some cases, it may be even the initial sign of an undetected HCC. Detection of malignant PVT in a patient with liver cirrhosis heavily affects the therapeutic strategy. Gray-scale ultrasound (US) is widely unreliable for differentiating benign and malignant thrombi. Although effective for this differential diagnosis, fine-needle biopsy remains an invasive technique. Sensitivity of color-doppler US in detection of malignant thrombi is highly dependent on the size of the thrombus. Contrast-enhanced computed tomography (CT) and contrast-enhanced magnetic resonance (MRI) can be useful to assess the nature of portal thrombus, while limited data are currently available about the role of positron emission tomography (PET) and PET-CT. In contrast with CT, MRI, PET, and PET-CT, contrast-enhanced ultrasound (CEUS) is a fast, effective, well tolerated and cheap technique, that can be performed even in the same session in which the thrombus has been detected. CEUS can be performed bedside and can be available also in transplanted patients. Moreover, CT and MRI only yield a snapshot analysis during contrast diffusion, while CEUS allows for a continuous real-time imaging of the microcirculation that lasts several minutes, so that the whole arterial phase and the late parenchymal phase of the contrast diffusion can be analyzed continuously by real-time US scanning. Continuous real-time monitoring of contrast diffusion entails an easy detection of thrombus maximum enhancement. Moreover, continuous quantitative analyses of enhancement (wash in - wash out studies) by CEUS during contrast diffusion is nowadays available in most CEUS machines, thus giving a more sophisticated and accurate evaluation of the contrast distribution and an increased confidence in diagnosis in difficult cases. In conclusion, CEUS is a very reliable technique with a high intrinsic sensitivity for portal vein patency assessment. More expensive and sophisticated techniques (i.e., CT, MRI, PET, and PET-CT) should only be indicated in undetermined cases at CEUS.     

Differentiation of atypical hepatic hemangioma from liver metastases: Diagnostic performance of a novel type of color contrast enhanced ultrasound

BACKGROUND In clinical practice,the diagnosis is sometimes difficult with contrast-enhanced ultrasound(CEUS)when the case has an atypical perfusion pattern.Color parametric imaging(CPI)is an analysis software for CEUS with better detection of temporal differences in CEUS imaging using arbitrary colors.It measures the differences in arrival time of the contrast agent in lesions so that the perfusion features of atypical hemangioma and colorectal cancer(CRC)liver metastasis can be distinguished.AIM To evaluate the role of a novel type of CPI of CEUS in the differential diagnosis of atypical hemangioma from liver metastases in patients with a history of CRC.METHODS From January 2016 to July 2018,42 patients including 20 cases of atypical hemangioma and 22 cases of liver metastases from CRC were enrolled.These patients had a mean age of 60.5±9.3 years(range:39-75 years).All patients received ultrasound,CEUS and CPI examinations.Resident and staff radiologists independently and retrospectively reviewed CEUS and CPI images.Two sets of criteria were assigned:(1)Routine CEUS alone;and(2)CEUS and CPI.The diagnostic sensitivity,specificity,accuracy and receiver operating characteristic(ROC)curve of resident and staff radiologists were analyzed.RESULTS The following CPI features were significantly different between liver hemangioma and liver metastases analyzed by staff and resident radiologists:Peripheral nodular enhancement(65%-70.0%vs 4.5%-13.6%,P<0.001,P=0.001),mosaic/chaotic enhancement(5%-10%vs 68.2%-63.6%,P<0.001,P<0.001)and feeding artery(20%vs 59.1%-54.5%,P=0.010,P=0.021).CPI imaging offered significant improvements in detection rates compared with routine CEUS in both resident and staff groups.By resident radiologists,the specificity and accuracy of CEUS+CPI were significantly increased compared with that of CEUS(77.3%vs 45.5%,P=0.030;78.6%vs 50.0%,P=0.006).In addition,the area under the curve(AUC)of CEUS+CPI was significantly higher than that of CEUS(0.803 vs 0.757,P=0.036).By staff radiologists,accuracy was improved in CEUS+CPI(81.0%vs 54.8%,P=0.010),whereas no significant differences in specificity and sensitivity were found(P=0.144,P=0.112).The AUC of CEUS+CPI was significantly higher than that of CEUS(0.890 vs 0.825,P=0.013)by staff radiologists.CONCLUSION Compared with routine CEUS,CPI could provide specific information on the hemodynamic features of liver lesions and help to differentiate atypical hemangioma from liver metastases in patients with CRC,even for senior radiologists.     

One stop shop approach for the diagnosis of liver hemangioma

Hepatic hemangioma is usually detected on a routine ultrasound examination because of silent clinical behaviour. The typical ultrasound appearance of hemangioma is easily recognizable and quickly guides the diagnosis without the need for further investigation. But there is also an entire spectrum of atypical and uncommon ultrasound features and our review comes to detail these particular aspects. An atypical aspect in standard ultrasound leads to the continuation of explorations with an imaging investigation with contrast substance [ultrasound/ computed tomography/or magnetic resonance imaging (MRI)]. For a clinician who practices ultrasound and has an ultrasound system in the room, the easiest, fastest, non-invasive and cost-effective method is contrast enhanced ultrasound (CEUS). Approximately 85% of patients are correctly diagnosed with this method and the patient has the correct diagnosis in about 30 min without fear of malignancy and without waiting for a computer tomography (CT)/MRI appointment. In less than 15% of patients CEUS does not provide a conclusive appearance; thus, CT scan or MRI becomes mandatory and liver biopsy is rarely required. The aim of this updated review is to synthesize the typical and atypical ultrasound aspects of hepatic hemangioma in the adult patient and to propose a fast, non-invasive and cost-effective clinical-ultrasound algorithm for the diagnosis of hepatic hemangioma.     

LI-RADS分级系统的临床应用现状分析

[摘要]?美国放射协会（American College of Radiology, ACR）2011年首次发布了肝脏影像报告和数据系统（liver imaging reporting and data system, LI-RADS）,目的是将高危肝细胞癌（hepatocellular carcinoma, HCC）患者检查图像的采集、分析、报告和数据收集标准化。LI-RADS最早是根据CT/MRI的影像学表现分类,随着超声造影（contrast-enhanced ultrasound, CEUS）在临床上的广泛应用,ACR 2016年发布了CEUS LI-RADS。尽管CEUS和CT/MRI对高危HCC患者的肝局灶性病变进行LI-RADS分类的概念和原则相似,但2者之间还是有显著区别。本综述旨在通过与CT/MRI LI-RADS进行比较,探讨CEUS LI-RADS的临床应用价值。     

Ultraschall in der Onkologie

This is a review on the role of ultrasound for early detection and staging of cancer. In breast cancer screening ultrasound serves to clarify mammographically unclear lesions and is a primary screening tool for hereditary breast cancer. Renal neoplasms are commonly diagnosed as incidental sonographic findings and in this case are more often in a curable stage than symptomatic neoplasms. In chronic hepatitis or liver cirrhosis the annual incidence of hepatocellular cancer is more than 2% and ultrasound is used as a screening tool with 60% sensitivity and 97% specificity. According to the literature the sensitivity of native ultrasound for detecting metastases is 60% and the sensitivity of contrast-enhanced ultrasound (CEUS) is 79% or higher, i.e comparable with the sensitivity of contrast-enhanced computed tomography (CT) or magnetic resonance imaging (MRI). Its role in staging is, however, limited as CT and MRI are necessary for local staging of the primary tumor and also include the liver. In the differential diagnosis of liver lesions the specificity of CEUS ranges from 82% to 99% depending on the lesion entity and is thereby comparable to contrast-enhanced CT. For staging of cervical lymph node metastases ultrasound is preferable to CT or MRI as the sensitivity lies between 79% and 90% and specificity is reported to be 90%.     

Contrast enhanced endoscopic ultrasound: More than just a fancy Doppler

Contrast enhanced endoscopic ultrasound (CEUS) is a new modality that takes advantage of vascular structure and blood flow to distinguish different clinical entities. Contrast agents are microbubbles that oscillate when exposed to ultrasonographic waves resulting in characteristic acoustic signals that are then converted to colour images. This permits exquisite imaging of macro- and microvasculature, providing information to help delineate malignant from non-malignant processes. The use of CEUS may significantly increase the sensitivity and specificity over conventional endoscopic ultrasound. Currently available contrast agents are safe, with infrequent adverse effects. This review summarizes the theory and technique behind CEUS and the current and future clinical applications.     

Response evaluation of chemotherapy in metastatic colorectal cancer by contrast enhanced ultrasound

AIM: To evaluate whether contrast enhanced ultrasound (CEUS) might also be used for response prediction and early response evaluation in patients receiving bevacizumab based chemotherapy for metastasized colorectal cancer.METHODS: Thirty consecutive patients with non primary resectable liver metastases from colorectal cancer underwent CEUS before treatment (CEUS date 1) and before the second (CEUS date 2) and fourth (CEUS date 3) cycle of bevacizumab based chemotherapy. Three parameters [PEAK, Time to peak (TTP) and RISE RATE]were correlated with radiological response.RESULTS: For neoadjuvant purpose a reduction of tumour mass was required to assume clinical response. Based on these response criteria there was a significant (P < 0.001) correlation in TTP between metastases of responders (9.08 s) and non-responders (14.76 s) archived on CEUS date 1. By calculating a standardized quotient (metastases divided by normal liver tissue) we were able to define a cut off, predicting response with a sensitivity of 92.3 % and a specificity of 100 %. To reflect a palliative intention only those patients with progressive disease were classified as non-responders. In this stetting TTP was also significantly (P < 0.01) different between responders and non-responders. In contrast, Peak and Rise rate did not show any significant difference between responder and non-responder.CONCLUSION: CEUS might serve as a surrogate marker to predict treatment response in patients with metastasized colorectal cancer who receive antiangiogenic therapy.     

Primary gastrointestinal stromal tumor of the liver： A case report

We report a case of primary gastrointestinal stromal tumor （GIST） of the liver. A 17-year-old man with a solid mass in the anterior segment of the right liver was asymptomatic with negative laboratory examinations with the exception of positive HBV. Contrast-enhanced ultrasound （CEUS） revealed a hypervascular lesion in the arterial phase and hypoechoic features during the portal and late phases. However, enhanced spiral computed tomography （CT） showed hypoattenuation in all three phases. Following biopsy, immunohistochemical evaluation demonstrated positive CDl17. Different imaging features of primary GISTs of the liver are due to pathological properties and different working systems between CEUS and enhanced spiral CT.     

Colorectal cancer:Current imaging methods and future perspectives for the diagnosis,staging and therapeutic response evaluation

In the last 10 years the mortality rate of colorectal cancer(CRC)has decreased by more than 20%due to the rising developments in diagnostic techniques and optimization of surgical,neoadjuvant and palliative therapies.Diagnostic methods currently used in the evaluation of CRC are heterogeneous and can vary within the countries and the institutions.This article aims to discuss in depth currently applied imaging modalities such as virtual computed tomography colonoscopy,endorectal ultrasound,computed tomography(CT)and magnetic resonance imaging(MRI)in the diagnosis of CRC.Special focus is put on the potential of recent diagnostic developments as diffusion weighted imaging MRI,MRI biomarkers(dynamic enhanced MRI),positron emission tomography with 2-(fluorine-18)-fluoro-2-deoxy-D-glucose(FDG-PET)combined with computed tomography(PET/CT)and new hepatobiliary MRI contrast agents.The precise role,advantage and disadvantages of these modalities are evaluated controversially in local staging,metastatic spread and treatment monitoring of CRC.Finally,the authors will touch upon the future perspectives in functional imaging evaluating the role of integrated FDG-PET/CT with perfusion CT,MRI spectroscopy of primary CRC and hepatic transit time analysis using contrast enhanced ultrasound and MRI in the detection of liver metastases.Validation of these newer imaging techniques may lead to significant improvements in the management of patients with colorectal cancer.     

Contrast-enhanced ultrasound in the diagnosis of nodules in liver cirrhosis

Contrast-enhanced ultrasound(CEUS)using microbubble contrast agents are useful for the diagnosis of the nodules in liver cirrhosis.CEUS can be used as a problem-solving method for indeterminate nodules on computed tomography(CT)or magnetic resonance imaging(MRI)or as an initial diagnostic test for small newly detected liver nodules.CEUS has unique advantages over CT and MRI including no renal excretion of contrast,real-time imaging capability,and purely intravascular contrast.Hepatocellular carcinoma(HCC)is characterized by arterial-phase hypervascularity and later washout(negative enhancement).Benign nodules such as regenerative nodules or dysplastic nodules are usually isoechoic or slightly hypoechoic in the arterial phase and isoechoic in the late phase.However,there are occasional HCC lesions with atypical enhancement including hypovascular HCC and hypervascular HCC without washout.Cholangiocarcinomas are infrequently detected during HCC surveillance and mostly show rimlike or diffuse hypervascularity followed by rapid washout.Hemangiomas are often found at HCC surveillance and are easily diagnosed by CEUS.CEUS can be effectively used in the diagnostic work-up of small nodules detected at HCC surveillance.CEUS is also useful to differentiate malignant and benign venous thrombosis and to guide and monitor the local ablation therapy for HCC.     

Contrast enhanced ultrasound (CEUS) imaging of solid benign focal liver lesions

Introduction: Ultrasound is well accepted worldwide for imaging of the liver. Absences of radiation exposure, low cost and large diffusion are some of the advantages that make this technique the first to be used in the assessment of focal liver lesions (FLL).

Areas covered: Contrast enhanced ultrasound (CEUS) has been introduced more than twenty years ago, and its detection rate is comparable to that of contrast enhanced magnetic resonance imaging (CEMRI) and contrast enhanced computed tomography (CECT). In this narrative review, we discuss the main CEUS features of benign liver lesions and controversies in published results including the gold standard chosen and the quality and knowledge of the preferred techniques.

Expert commentary: CEUS is safe and allows an immediate evaluation of the nature of FLL. CEUS permits differentiation between malignant and benign FLL in healthy liver parenchyma by analysing the arterial, portal venous and late phases. CEMRI and CECT are reliable to characterize FLL but higher costs, radiation exposure, nephrotoxicity (in particular for CECT) and absence of real time imaging limit the appropriate evaluation of FLL. Therefore CEUS can be preferred in most clinical situations, and when results are unclear or suggestive for malignant FLL, biopsy and histological examination can be directly initiated avoiding unnecessary additional imaging.     

Hepatocellular carcinoma after ablation:The imaging follow-up scheme

Percutaneous ablation using thermal or chemical methods has been widely used in the treatment of hepatocellular carcinoma (HCC).Nowadays,contrast-enhanced imaging modalities such as computed tomography (CT),magnetic resonance imaging (MRI),and contrast-enhanced ultrasound (CEUS) are widely used to evaluate local treatment response after ablation therapies.CEUS is gaining increasing attention due to its characteristics including real-time scanning,easy performance,lack of radiation,wide availability,and lack of allergy reactions.Several studies have documented that CEUS is comparable to CT or MRI in evaluating local treatment efficacy within 1 mo of treatment.However,little information is available regarding the role of CEUS in the followup assessment after first successful ablation treatment.Zheng et al found that in comparison with contrastenhanced computed tomography (CECT),the sensitivity,specificity,positive predictive value,negative predictive value and overall accuracy of CEUS in detecting local tumor progression (LTP) were 67.5%,97.4%,81.8%,94.4% and 92.3%,respectively,and were 77.7%,92.0%,92.4%,76.7% and 84.0%,respectively for the detection of new intrahepatic recurrence.They concluded that the sensitivity of CEUS in detecting LTP and new intrahepatic recurrence after ablation is relatively low in comparison with CECT,and CEUS cannot replace CECT in the follow-up assessment after percutaneous ablation for HCC.These results are meaningful and instructive,and indicated that in the follow-up period,the use of CEUS alone is not sufficient.In this commentary,we discuss the discordance between CT and CEUS,as well as the underlying mechanisms involved.We propose the combined use of CT and CEUS which will reduce false positive and negative results in both modalities.We also discuss future issues,such as an evidence-based ideal imaging follow-up scheme,and a cost-effectiveness analysis of this imaging follow-up scheme.     

Vascular complications after adult living donor liver transplantation:Evaluation with ultrasonography

Living donor liver transplantation(LDLT) has beenwidely used to treat end-stage liver disease with improvement in surgical technology and the application of new immunosuppressants. Vascular complications after liver transplantation remain a major threat to the survival of recipients. LDLT recipients are more likely to develop vascular complications because of their complex vascular reconstruction and the slender vessels. Early diagnosis and treatment are critical for the survival of graft and recipients. As a non-invasive, cost-effective and non-radioactive method with bedside availability, conventional gray-scale and Doppler ultrasonography play important roles in identifying vascular complications in the early postoperative period and during the follow-up. Recently, with the detailed vascular tracing and perfusion visualization, contrastenhanced ultrasound(CEUS) has significantly improved the diagnosis of postoperative vascular complications. This review focuses on the role of conventional grayscale ultrasound, Doppler ultrasound and CEUS for early diagnosis of vascular complications after adult LDLT.     

Diagnostic imaging of liver tumours. Current status

Nowadays, contrast enhanced ultrasound (CEUS) is an imaging technique equivalent to multidetector computed tomography (MDCT) and magnetic resonance imaging (MRI) for the detection and characterization of focal liver lesions. These methods have comparable sensitivity and specificity in differentiating a liver lesion as "benign" or "malignant". For benign lesions, CEUS is the recommended method of the choice. In unclear cases, or if CEUS is not available, MRI or CT are the methods of the second choice. If a benign tumor remains unclear, then a needle biopsy is recommended. In the case of a malignant tumor, it is necessary to use a second imaging technique besides CEUS. In addition to the detection and characterization of a liver tumor, CT and MRI provide information on the extrahepatic spread of a tumor, particularly into the lung or retroperitoneum. The rapid development of surgical and interventional approaches requires accurate information on the character and number of malignant liver lesions. Therefore, the combined use of CEUS and MDCT or MRI currently represents the most modern and optimal standard of imaging. The standardization of CT and MRI protocols has increased the general diagnostic level of these images. Adequate training and a certificate for the use of CEUS is recommended in order to maintain the high diagnostic level of this method (EFSUMB guide lines). An optimal interdisciplinary imaging strategy for focal liver lesions minimises unnecessary invasive or potentially harmful imaging and reduces health costs.     

Bildgebende Diagnostik von Lebertumoren

Nowadays, contrast enhanced ultrasound (CEUS) is an imaging technique equivalent to multidetector computed tomography (MDCT) and magnetic resonance imaging (MRI) for the detection and characterization of focal liver lesions. These methods have comparable sensitivitiy and specifity in differentiating a liver lesion as “benign” or “malignant”. For benign lesions, CEUS is the recommended method of the choice. In unclear cases, or if CEUS is not available, MRI or CT are the methods of the second choice. If a benign tumor remains unclear, then a needle biopsy is recommended. In the case of a malignant tumor, it is necessary to use a second imaging technique besides CEUS. In addition to the detection and characterization of a liver tumor, CT and MRI provide information on the extrahepatic spread of a tumor, particularly into the lung or retroperitoneum. The rapid development of surgical and interventional approaches requires accurate information on the character and number of malignant liver lesions. Therefore, the combined use of CEUS and MDCT or MRI currently represents the most modern and optimal standard of imaging. The standardization of CT and MRI protocols has increased the general diagnostic level of these images. Adequate training and a certificate for the use of CEUS is recommended in order to maintain the high diagnostic level of this method (EFSUMB guide lines). An optimal interdisciplinary imaging strategy for focal liver lesions minimises unnecessary invasive or potentially harmful imaging and reduces health costs.