The role of contrast-enhanced ultrasound in planning treatment protocols for hepatocellular carcinoma before radiofrequency ablation

Morphometric characterization and temporal temperature measurements during hepatic microwave ablation in swine

PURPOSE

Heat-induced destruction of cancer cells via microwave ablation (MWA) is emerging as a viable treatment of primary and metastatic liver cancer. Prediction of the impacted zone where cell death occurs, especially in the presence of vasculature, is challenging but may be achieved via biophysical modeling. To advance and characterize thermal MWA for focal cancer treatment, an in vivo method and experimental dataset were created for assessment of biophysical models designed to dynamically predict ablation zone parameters, given the delivery device, power, location, and proximity to vessels.

MATERIALS AND METHODS

MWA zone size, shape, and temperature were characterized and monitored in the absence of perfusion in ex vivo liver and a tissue-mimicking thermochromic phantom (TMTCP) at two power settings. Temperature was monitored over time using implanted thermocouples with their locations defined by CT. TMTCPs were used to identify the location of the ablation zone relative to the probe. In 6 swine, contrast-enhanced CTs were additionally acquired to visualize vasculature and absence of perfusion along with corresponding post-mortem gross pathology.

RESULTS

Bench studies demonstrated average ablation zone sizes of 4.13±1.56cm2 and 8.51±3.92cm2, solidity of 0.96±0.06 and 0.99±0.01, ablations centered 3.75cm and 3.5cm proximal to the probe tip, and temperatures of 50 ºC at 14.5±13.4s and 2.5±2.1s for 40W and 90W ablations, respectively. In vivo imaging showed average volumes of 9.8±4.8cm3 and 33.2±28.4cm3 and 3D solidity of 0.87±0.02 and 0.75±0.15, and gross pathology showed a hemorrhagic halo area of 3.1±1.2cm2 and 9.1±3.0cm2 for 40W and 90W ablations, respectfully. Temperatures reached 50ºC at 19.5±9.2s and 13.0±8.3s for 40W and 90W ablations, respectively.

CONCLUSION

MWA results are challenging to predict and are more variable than manufacturer-provided and bench predictions due to vascular stasis, heat-induced tissue changes, and probe operating conditions. Accurate prediction of MWA zones and temperature in vivo requires comprehensive thermal validation sets.

Contrast-enhanced ultrasonography to guide diagnostic and therapeutic interventional procedures

Although not necessary for the vast majority of ultrasound-guided procedures, intravenous contrast agents can be useful for procedures aimed at lesions that require contrast enhancement to be seen on ultrasonography. Using contrast-enhanced ultrasonography to guide procedures has two drawbacks: first, because enhancement from ultrasound contrast agents is short lived, it is often necessary to plan several injections; second, because the needle is poorly seen on contrast-enhanced ultrasonography, a dual image display format is necessary. Contrast-enhanced ultrasonography can be used for planning and monitoring diagnostic and therapeutic procedures, for guiding the procedures, and for follow-up. Using contrast-enhanced ultrasonography enables better results in both types of procedures; moreover, it can be used within cavities.

Comparison of Contrast-Enhanced Ultrasonography to Color Doppler Ultrasound in Evaluation of Carotid Body Tumors

Objective

The objectives of this study were to prospectively 1) explore the characteristics and enhanced patterns of carotid body tumors (CBTs) at color Doppler ultrasound (CDU) and contrast-enhanced ultrasonography (CEUS) qualitatively and quantitatively and 2) compare CDU and CEUS for their morphology and vascularity signature.

Methods

CDU and CEUS with Sonovue^® were used to evaluate 25 CBT lesions. The comparison between these ultrasonic modalities included the size, Shamblin type, vascularity, and feeding vessels of the lesion areas. The time–intensity curve (TIC) analysis was used to obtain the dynamics of the contrast-enhancement features of CBTs.

Results

The TIC analysis presented a fast wash-in [wash-in time: 3.00 ± 1.10 s, mean ± SD] and slow wash-out [wash-out time: 58.79 ± 24.21 s, mean ± SD] pattern in the CBT lesions, with a high area under the curve (AUC) of 669.68 ± 143.46 mm² (mean ± SD). In comparison with CDU, CEUS was superior in identifying Shamblin type I or III CBT lesions (χ² = 17.389, p=0.002). It detected a significant difference in the AUC between moderate and marked vascularity groups (563.33 ± 102.63 vs. 707.22 ± 138.81, t=-2.311, p=0.031.), while CDU observed no significant difference between these two groups. Although CDU was more sensitive than CEUS in detecting feeding vessels (100% vs. 88%), CEUS better visualized the origins of feeding vessels (χ² = 9.162, p=0.010).

Conclusion

CEUS can better investigate the Shamblin type and vascularity of CBT lesions than CDU. CBTs displayed a fast wash-in, slow wash-out pattern with high AUC in the TIC analysis in the CEUS mode. CDU is more sensitive in detecting feeding vessels than CEUS, while CEUS can better visualize the origins of feeding vessels.

Contrast enhancement for ultrasound-guided interventions: when to use it and what to expect?

The use of contrast-enhanced ultrasonography (CEUS) has recently become synonymous with high-standard ultrasonography (US). From expanding the reach of US diagnostics to improving the precision of various invasive procedures, CEUS is rapidly becoming a standard in numerous niches. However, proficiency in CEUS comes with a cost, both from a learning curve and material standpoint, and as every growing field, lacks firm evidence and standardization. Therefore, in the current paper, we aim to provide an evidence-based review of available methods and to discuss the advantages and pitfalls of CEUS in interventional procedures, trying to provide strong evidence whenever available, or at least an educated expert opinion if data are lacking.

Contrast-enhanced ultrasonography to guide diagnostic and therapeutic interventional procedures

Although not necessary for the vast majority of ultrasound-guided procedures, intravenous contrast agents can be useful for procedures aimed at lesions that require contrast enhancement to be seen on ultrasonography. Using contrast-enhanced ultrasonography to guide procedures has two drawbacks: first, because enhancement from ultrasound contrast agents is short lived, it is often necessary to plan several injections; second, because the needle is poorly seen on contrast-enhanced ultrasonography, a dual image display format is necessary. Contrast-enhanced ultrasonography can be used for planning and monitoring diagnostic and therapeutic procedures, for guiding the procedures, and for follow-up. Using contrast-enhanced ultrasonography enables better results in both types of procedures; moreover, it can be used within cavities.

Ten-year survival of hepatocellular carcinoma patients undergoing radiofrequency ablation as a first-line treatment

AIM: To investigate the long-term survival and prognostic factors in hepatocellular carcinoma (HCC) patients undergoing radiofrequency ablation (RFA) as a first-line treatment.

METHODS: From 2000 to 2013, 316 consecutive patients with 404 HCC (1.0-5.0 cm; mean: 3.2 ± 1.1 cm) underwent ultrasonography-guided percutaneous RFA as a first-line treatment. There were 250 males and 66 females with an average age of 60.1 ± 10.8 years (24-87 years). Patients were followed for 1 year to > 10 years after RFA (234, 181, 136, and 71 for 3, 5, 7, and 10 years, respectively). Overall local response rates and long-term survival rates were assessed. Survival results were generated using Kaplan-Meier estimates, and multivariate analysis was performed using the Cox regression model.

RESULTS: In total, 548 RFA sessions were performed and major complications occurred in 10 sessions (1.8%). Local tumor progression and/or new tumor development were observed in 43.3% (132/305) of the patients during the follow-up period. Overall 5- and 10-year survival rates were 49.7% and 28.4%, respectively. Based on multivariate analysis, three factors were identified as independent prognostic factors for overall survival: Child-Pugh classification (HR = 4.054, P < 0.001), portal vein hypertension (HR = 2.743, P = 0.002), and tumor number (HR = 2.693, P = 0.003). The local progression-free 5- and 10-year survival rates were 42.7% and 19.5%. In addition to the Child-Pugh classification and the number of tumors, the number of RFA sessions (HR = 1.550, P = 0.002) was associated with local progression-free survival.

CONCLUSION: RFA can achieve acceptable outcomes for HCC patients as a first-line treatment, especially for patients with Child-Pugh class A, patients with a single tumor and patients without portal vein hypertension.

CT imaging during microwave ablation: analysis of spatial and temporal tissue contraction

PURPOSE

To analyze the spatial distribution and temporal development of liver tissue contraction during high-temperature ablation by using intraprocedural computed tomography (CT) imaging.

METHODS

A total of 46 aluminum fiducial markers were positioned in a 60 × 45 mm grid, in a single plane, around a microwave ablation antenna in each of six ex vivo bovine liver samples. Ablations were performed for 10 min at 100 W. CT data of the liver sample were acquired every 30 s during ablation. Fiducial motion between acquisitions was tracked in postprocessing and used to calculate measures of tissue contraction and contraction rates. The spatial distribution and temporal evolution of contraction were analyzed.

RESULTS

Fiducial displacement indicated that the zone measured postablation was 8.2 ± 1.8 mm (∼20%) smaller in the radial direction and 7.1 ± 1.0 mm (∼10%) shorter in the longitudinal direction than the preablation tissue dimension. Therefore, the total ablation volume was reduced from its preablation value by approximately 45%. Very little longitudinal contraction was noted in the distal portion of the ablation zone. Central tissues contracted more than 60%, which was near an estimated limit of ∼70% based on initial water content. More peripheral tissues contracted only 15% in any direction. Contraction rates peaked during the first 60 s of heating with a roughly exponential decay over time.

CONCLUSIONS

Ablation zones measured posttreatment are significantly smaller than the pretreatment tissue dimensions. Tissue contraction is spatially dependent, with the greatest effect occurring in the central ablation zone. Contraction rate peaks early and decays over time.

Image-guided tumor ablation: standardization of terminology and reporting criteria--a 10-year update

Image-guided tumor ablation has become a well-established hallmark of local cancer therapy. The breadth of options available in this growing field increases the need for standardization of terminology and reporting criteria to facilitate effective communication of ideas and appropriate comparison among treatments that use different technologies, such as chemical (eg, ethanol or acetic acid) ablation, thermal therapies (eg, radiofrequency, laser, microwave, focused ultrasound, and cryoablation) and newer ablative modalities such as irreversible electroporation. This updated consensus document provides a framework that will facilitate the clearest communication among investigators regarding ablative technologies. An appropriate vehicle is proposed for reporting the various aspects of image-guided ablation therapy including classification of therapies, procedure terms, descriptors of imaging guidance, and terminology for imaging and pathologic findings. Methods are addressed for standardizing reporting of technique, follow-up, complications, and clinical results. As noted in the original document from 2003, adherence to the recommendations will improve the precision of communications in this field, leading to more accurate comparison of technologies and results, and ultimately to improved patient outcomes.

Image-guided tumor ablation: standardization of terminology and reporting criteria--a 10-year update

Image-guided tumor ablation has become a well-established hallmark of local cancer therapy. The breadth of options available in this growing field increases the need for standardization of terminology and reporting criteria to facilitate effective communication of ideas and appropriate comparison among treatments that use different technologies, such as chemical (eg, ethanol or acetic acid) ablation, thermal therapies (eg, radiofrequency, laser, microwave, focused ultrasound, and cryoablation) and newer ablative modalities such as irreversible electroporation. This updated consensus document provides a framework that will facilitate the clearest communication among investigators regarding ablative technologies. An appropriate vehicle is proposed for reporting the various aspects of image-guided ablation therapy including classification of therapies, procedure terms, descriptors of imaging guidance, and terminology for imaging and pathologic findings. Methods are addressed for standardizing reporting of technique, follow-up, complications, and clinical results. As noted in the original document from 2003, adherence to the recommendations will improve the precision of communications in this field, leading to more accurate comparison of technologies and results, and ultimately to improved patient outcomes. Online supplemental material is available for this article .

Acoustic radiation force impulse elastography for efficacy evaluation after hepatocellular carcinoma radiofrequency ablation: a comparative study with contrast-enhanced ultrasound

Aim. To explore acoustic radiation force impulse (ARFI) elastography in assessing residual tumors of hepatocellular carcinoma (HCC) after radiofrequency ablation (RFA). Materials and Methods. There were 83 HCC lesions among 72 patients. All patients were examined with ARFI, contrast enhanced ultrasound (CEUS), and CT or MRI. Tumor brightness on virtual touch tissue imaging (VTI) and shear wave velocity (SWV) were assessed before and approximately one month after RFA. Results. There were 14 residual tumors after RFA. VTI showed that all the tumors were darker after RFA. VTI was not able to distinguish the ablated lesions and the residual tumors. 13 residual tumor lesions were detected by CEUS. All completely ablated nodules had SWV demonstration of x.xx., while with those residual nodules, 6 tumors had x.xx measurement and 8 tumors had measurable SWV. nine lesions with residual tumors occurred in cirrhosis subjects and 5 lesions with residual tumors occurred in fibrosis subjects; there was no residual tumor in the normal liver subjects. Conclusion. VTI technique cannot demonstrate residual tumor post RFA. While SWV measurement of less than x.xx is likely associated with residual tumors, measurement of less than x.xx cannot exclude residual tumors. Liver cirrhosis is associated with decreased chance of a complete ablation.

Computational modelling of microwave tumour ablations

Microwave tissue heating is being increasingly utilised in several medical applications, including focal tumour ablation, cardiac ablation, haemostasis and resection assistance. Computational modelling of microwave ablations is a precise and repeatable technique that can assist with microwave system design, treatment planning and procedural analysis. Advances in coupling temperature and water content to electrical and thermal properties, along with tissue contraction, have led to increasingly accurate computational models. Developments in experimental validation have led to broader acceptability and applicability of these newer models. This review will discuss the basic theory, current trends and future direction of computational modelling of microwave ablations.

Role of contrast-enhanced ultrasonography in percutaneous radiofrequency ablation of liver metastases and efficacy evaluation

OBJECTIVE

To retrospectively investigate the role of contrast-enhanced ultrasonography (CEUS) in percutaneous radiofrequency ablation (RFA) in patients with liver metastases and evaluate the therapeutic efficacy of RFA assisted by CEUS.

METHODS

From May 2004 to September 2010, 136 patients with 219 liver metastatic lesions received CEUS examination 1 h before RFA (CEUS group), and other 126 patients with 216 lesions without CEUS examination in the earlier period were served as a historical control group. The mean tumor size was 3.2 cm and the mean tumor number was 1.6 in the CEUS group, while 3.4 cm and 1.7 in the control group, respectively (P>0.05). The clinical characteristics, recurrence results and survival outcomes were compared between two groups.

RESULTS

In the CEUS group, two isoechoic tumors were not demonstrated on unenhanced ultrasonography (US), and 63 (47%) of 134 tumors examined with CEUS were 0.3 cm larger than with unenhanced US. Furthermore, in 18.4% of 136 patients, additional 1-3 tumors were detected on CEUS. The CEUS group showed higher early tumor necrosis and lower intrahepatic recurrence than the control group. The 3-year overall survival (OS) rate and the 3-year local recurrence-free survival (LRFS) rate in the CEUS group were 50.1% and 38.3%, in contrast to 25.3% and 19.3% in the control group, respectively (P=0.002 and P<0.001).

CONCLUSIONS

CEUS provides important information for RFA treatment in patients with liver metastases and better therapeutic effect could be attained.

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 follow-up assessment after first successful ablation treatment. Zheng et al found that in comparison with contrast-enhanced 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.

Guidelines and good clinical practice recommendations for Contrast Enhanced Ultrasound (CEUS) in the liver - update 2012: A WFUMB-EFSUMB initiative in cooperation with representatives of AFSUMB, AIUM, ASUM, FLAUS and ICUS

Initially, a set of guidelines for the use of ultrasound contrast agents was published in 2004 dealing only with liver applications. A second edition of the guidelines in 2008 reflected changes in the available contrast agents and updated the guidelines for the liver, as well as implementing some non-liver applications. Time has moved on, and the need for international guidelines on the use of CEUS in the liver has become apparent. The present document describes the third iteration of recommendations for the hepatic use of contrast enhanced ultrasound (CEUS) using contrast specific imaging techniques. This joint WFUMB-EFSUMB initiative has implicated experts from major leading ultrasound societies worldwide. These liver CEUS guidelines are simultaneously published in the official journals of both organizing federations (i.e., Ultrasound in Medicine and Biology for WFUMB and Ultraschall in der Medizin/European Journal of Ultrasound for EFSUMB). These guidelines and recommendations provide general advice on the use of all currently clinically available ultrasound contrast agents (UCA). They are intended to create standard protocols for the use and administration of UCA in liver applications on an international basis and improve the management of patients worldwide.

Role of contrast enhanced ultrasound in radiofrequency ablation of metastatic liver carcinoma

OBJECTIVE

To investigate the application of contrast enhanced ultrasound (CEUS) in planning and guiding for radiofrequency ablation (RFA) for metastatic liver carcinoma (MLC).

METHODS

One hundred and thirty-five patients with clinically and pathologically diagnosed MLC (from gastrointestinal tumors) were included in the present study, and 104 of them had received CEUS prior to RFA to assess the number, size, shape, infiltration, location and enhancing features of the lesions. Among the 104 patients, 21 (20.1%) were excluded from RFA treatment due to too many lesions or large infiltrative range based on CEUS. The remaining 83 patients with 147 lesions underwent RFA (group A). During the same period, other 31 patients with 102 lesions serving as control group were treated based on findings of conventional ultrasound without contrast (group B). The patients underwent follow-up enhanced CT at the 1st month, and then every 3-6 months after RFA. The tumor was considered as early necrosis if no contrast enhancement was detected in the treated area on the CT scan at the 1st month.

RESULTS

In group A, 72 of 147 MLC lesions (48.9%) showed increased sizes on CEUS. Among them, 48 lesions (66.6%) appeared enlarged in arterial phase, and 24 (33.3%) showed enlarged hypoechoic area in parenchymal phase. CEUS showed total 61 additional lesions in 35 patients (42.1%) (ranged from 8 to 15 mm) compared with conventional ultrasound (US), and 42 (68.8%) of them were visualized in parenchymal phase only. There were total 208 lesions in group A underwent RFA with CEUS planning, and the tumor necrosis rate was 94.2% (196/208). In this group, local recurrence was found in 16 lesions (7.7%) during 3-42 months' following up, and new metastases were seen in 30 cases (36.1%). For group B, the tumor necrosis rate was 86.3% (88/102), local recurrence in 17 lesions (16.7%), and new metastases in 13 cases (41.9%). Tumor early necrosis and recurrence rates were significantly different between the two groups (P=0.018, P=0.016, respectively).

CONCLUSION

CEUS played an important role in RFA for liver metastases by candidate selecting and therapy planning, which helped to improve the outcome of the treatment.

[Radiological diagnosis of hepatocellular carcinoma in 2010]

The aim of diagnosis imaging is to detect hepatocellular carcinoma at an early stage, when a curative treatment is available. Biopsy is no longer required prior to treatment, and diagnosis of hepatocellular carcinoma is heavily dependent of imaging characteristics. Therefore, the purpose of this article is to describe the typical features of small (<20mm) and larger hepatocellular carcinomas with noninvasive diagnostic criteria, including ultrasound, computed tomography and MRI. Advances in these imaging modalities have greatly improved the detection of small hepatic nodules on liver cirrhosis, including the different steps of carcinogenesis, from regenerative to dysplastic nodules, and we emphasize the difficulties of radiological differentiation of precancerous lesions and small hepatocellular carcinomas.

Imaging in interventional oncology

Medical imaging in interventional oncology is used differently than in diagnostic radiology and prioritizes different imaging features. Whereas diagnostic imaging prioritizes the highest-quality imaging, interventional imaging prioritizes real-time imaging with lower radiation dose in addition to high-quality imaging. In general, medical imaging plays five key roles in image-guided therapy, and interventional oncology, in particular. These roles are (a) preprocedure planning, (b) intraprocedural targeting, (c) intraprocedural monitoring, (d) intraprocedural control, and (e) postprocedure assessment. Although many of these roles are still relatively basic in interventional oncology, as research and development in medical imaging focuses on interventional needs, it is likely that the role of medical imaging in intervention will become even more integral and more widely applied. In this review, the current status of medical imaging for intervention in oncology will be described and directions for future development will be examined.

Current status of radiofrequency ablation of hepatocellular carcinoma

Loco-regional treatments for hepatocellular carcinoma (HCC) are important alternatives to curative transplantation or resection. Among them, radiofrequency ablation (RFA) is accepted as the most popular technique showing excellent local tumor control and acceptable morbidity. The current role of RFA is well documented in the evidence-based practice guidelines of European Association of Study of Liver, American Association of Study of the Liver Disease and Japanese academic societies. Several randomized controlled trials have confirmed that RFA is superior to percutaneous ethanol injections in terms of local tumor control and survival. The overall survival after RFA is comparable to after surgical resection in a selected group of patients with smaller (< 3 cm) tumors. Currently, the clinical benefits of combined RFA with transarterial chemoembolization for intermediate stage HCC are increasingly being explored. Here we review the ongoing technical advancements of RFA and future potential.

Percutaneous radiofrequency ablation as first-line treatment for small hepatocellular carcinoma: results and prognostic factors on long-term follow up

BACKGROUND AND AIMS

We evaluated the prognosis and associated factors in patients with small hepatocellular carcinoma (HCC; up to 3 nodules, each up to 3 cm in diameter) treated with percutaneous radiofrequency ablation (RFA) as first-line treatment.

METHODS

Eighty-eight consecutive patients who underwent percutaneous RFA as first-line treatment were enrolled, among whom 70 who had hypervascular HCC nodules which were treated by a combination of transcatheter arterial chemoembolization and RFA. RFA was repeated until an ablative margin was obtained.

RESULTS

The rate of local tumor progression at 1 and 3 years was 4.8% and 4.8%, respectively. The rate of overall survival at 3 and 5 years was 83.0% and 70.0%, and the rate of disease-free survival at 3 and 5 years was 34.0% and 24.0%, respectively. On multivariate analysis, age (< 70 years; hazard ratio [HR] = 2.341, 95% confidence interval [CI] = 1.101-4.977, P = 0.027) and indocyanine green retention rate at 15 min (< 15%; HR = 3.621, 95% CI = 1.086-12.079, P = 0.036) were statistically significant determinants of overall survival, while tumor number (solitary, HR = 2.465, 95% CI = 1.170-5.191, P = 0.018) was identified for disease-free survival. Overall survival of patients with early recurrence after RFA was significantly worse than that of patients with late recurrence. Tumor size was the only independent risk factor of early recurrence after RFA of HCC (tumor size > 2 cm; risk ratio [RR] = 4.629, 95% CI = 1.241-17.241, P = 0.023).

CONCLUSION

Percutaneous RFA under the protocol reported here has the potential to provide local tumor control for small HCC. In addition to host factors, time interval from RFA to recurrence was an important determinant of prognosis.

[Contrast-enhanced ultrasound and liver imaging: review of the literature]

The advent of second-generation microbubble ultrasound contrast agents and the development of contrast specific ultrasound techniques improved the ability of contrast enhanced ultrasound (CEUS) in detecting and characterizing focal liver lesions, opening new prospects in liver imaging. A Medline search in June 2008 identified 72 published studies that used CEUS in focal liver lesion detection, characterization, and follow-up to monitor tumor ablation procedures and antiangiogenic treatment. The purpose of this paper, based on literature review, is to describe the technical recommendations when using CEUS for liver imaging and to define the different vascular patterns of the most relevant benign and malignant lesions. Diagnostic performance of CEUS and the important clinical indications are also presented and discussed. CEUS is increasingly accepted in clinical use for diagnostic imaging and post-interventional workup liver imaging. It may replace many computed tomography and magnetic resonance imaging examinations in the near future, according to the European Federation of Societies for Ultrasound in Medicine and Biology guidelines.

Radiological diagnosis of hepatocellular carcinoma

Treatment of hepatocellular carcinomas (HCC) is often complicated by the fact that early HCCs are mostly asymptomatic and the carcinoma is often discovered at an advanced stage. The aim of diagnostic imaging is to detect HCC at an early stage, when curative options are available. In recent years, there have been many efforts to improve early detection of small HCC. The purpose of this article is to describe the pertinent findings of HCCs in non-invasive, diagnostic imaging, including ultrasound, computed tomography, as well as modern magnetic resonance imaging techniques. Special emphasis is given to the frequently addressed difficulties of differentiation of precancerous lesions and small HCCs. A non-invasive diagnostic approach is considered with a review of the literature.