Ultrasound of focal liver lesions

Potential role of Fibrosis-4 score in hepatocellular carcinoma screening: The Kangbuk Samsung Health Study

AIM

Hepatocellular carcinoma (HCC) is a major cause of cancer-related death, with low survival rates worldwide. Fatty liver disease (FLD) significantly contributes to HCC. We studied the screening performance of different methods for identifying HCC in patients with FLD or with metabolic risk factors for FLD.

METHODS

Korean adults (n = 340 825) without a prior HCC diagnosis were categorized into four groups: normal (G1), ≥2 metabolic risk factors (G2), FLD (G3), and viral liver disease or liver cirrhosis (G4). The National Cancer Registry data were used to identify HCC cases within 12 months. We assessed the area under the receiver operating characteristic curve, sensitivity, specificity, and positive and negative predictive values of individual or combined screening methods.

RESULTS

In 93 HCC cases, 71 were identified in G4, whereas 20 cases (21.5%) in G2 and G3 combined where ultrasound and Fibrosis-4 performed similarly to alpha-fetoprotein and ultrasound. In G2, Fibrosis-4 and ultrasound had the highest area under the receiver operating characteristic curve (0.93 [0.87-0.99]), whereas in G3, the combined screening methods had the highest area under the receiver operating characteristic curve (0.98 [0.95-1.00]). The positive predictive value was lower in G2 and G3 than in G4, but was >5% when restricted to a high Fibrosis-4 score.

CONCLUSIONS

More than 21% of HCC cases were observed in patients with diagnosed FLD or at risk of FLD with metabolic risk factors. Nevertheless, screening for HCC in individuals without cirrhosis or viral hepatitis yielded very low results, despite the potential value of the Fibrosis-4 score in identifying individuals at high risk of HCC.

Multimodality Imaging of Primary Hepatic Lymphoma: A Case Report and a Literature Review

Primary hepatic lymphoma (PHL) is a rare form of non-Hodgkin lymphoma primarily affecting the liver. We present a case of an 84-year-old man diagnosed with PHL, incidentally detected during abdominal ultrasonography. The ultrasonography showed a hypoechoic nodule. When examined by CEUS, the nodule showed hyperenhancement in the arterial phase and hypoenhancement in the portal and late phases. Conversely, CECT demonstrated hypoenhancement through all the phases. The patient declined a tumor biopsy and opted for follow-up care. Ten months later, the lobular mass had increased from 15 mm to 65 mm, presenting as hypoechogenic and demonstrating the "vessel-penetrating sign" on color Doppler imaging. CEUS revealed reticulated enhancement, indicating intratumoral vessels. The mass displayed hypoattenuation on plain CT, hypointensity in T1-weighted images, and hyperintensity in T2-weighted images and exhibited significant restriction in diffusion-weighted images. Both CECT and contrast-enhanced MRI exhibited hypoenhancement. The patient underwent a partial hepatic segmentectomy, and the mass was pathologically diagnosed as a diffuse large B-cell lymphoma. Subsequent postoperative radiological examinations revealed no other lesions, confirming the diagnosis of PHL. Our report highlights specific ultrasonographic signs of PHL observed from an early stage and presents a review of the relevant literature.

[Ultrasound diagnostics of the liver : Principles and important pathologies]

Diffuse changes in the liver parenchyma, focal lesions and blood flow in hepatic vessels can be assessed using ultrasound. Screening by ultrasound can be used to detect hepatocellular carcinomas as possible malignant sequelae of liver cirrhosis. As metastases are far more frequent than primary malignant liver tumors, secondary malignant neoplasms should be taken into consideration as a differential diagnosis in the presence of focal liver lesions. This particularly concerns patients with a known metastatic disease. Benign focal liver lesions are often incidentally discovered in women of childbearing age. Cysts, hemangiomas and focal nodular hyperplasia mostly show typical morphological features in ultrasound and do not require further follow-up; however, with hepatic adenomas, regular follow-up is recommended due to the risk of bleeding and/or malignant transformation.

Microvascular flow imaging to differentiate focal hepatic lesions: the spoke-wheel pattern as a specific sign of focal nodular hyperplasia

Microvascular flow imaging (MVFI) is an advanced Doppler ultrasound technique designed to detect slow-velocity blood flow in small-caliber microvessels. This technique is capable of realtime, highly detailed visualization of tumor vessels without using a contrast agent. MVFI has been recently applied for the characterization of focal liver lesions and has revealed typical vascularity distributions in multiple types thereof. Focal nodular hyperplasia (FNH) constitutes an important differential diagnosis of malignant liver tumors. In this essay, we provide iconographic documentation of the MVFI appearance of FNH and other common solid liver lesions. Identifying the typical patterns of vascularity, including the spoke-wheel pattern with MVFI, can expedite the diagnosis, spare patients from unnecessary procedures, and save costs.

Benign liver lesions 2022: Guideline for clinical practice of Associazione Italiana Studio del Fegato (AISF), Società Italiana di Radiologia Medica e Interventistica (SIRM), Società Italiana di Chirurgia (SIC), Società Italiana di Ultrasonologia in Medicina e Biologia (SIUMB), Associazione Italiana di Chirurgia Epatobilio-Pancreatica (AICEP), Società Italiana Trapianti d'Organo (SITO), Società Italiana di Anatomia Patologica e Citologia Diagnostica (SIAPEC-IAP) - Part I - Cystic lesions

Benign liver lesions are increasingly diagnosed in daily clinical practice due to the growing use of imaging techniques for the study of the abdomen in patients who have non-specific symptoms and do not have an increased risk of hepatic malignancy. They include simple or parasitic cysts and solid benign tumors which differ widely in terms of prevalence, clinical relevance, symptoms and natural history and often lead to significant clinical problems relating to diagnosis and clinical management. Following the need to have updated guidelines on the management of benign focal liver lesions, the Scientific Societies mainly involved in their management have promoted the drafting of a new dedicated document. This document was drawn up according to the present Italian rules and methodologies necessary to produce clinical, diagnostic, and therapeutic guidelines based on evidence. Here we present the first part of the guideline, concerning the characterization of focal hepatic lesions detected by ultrasound, and the diagnosis and clinical management of simple and parasitic hepatic cysts, and of polycystic liver disease.

Deep Learning for the Detection, Localization, and Characterization of Focal Liver Lesions on Abdominal US Images

Purpose

To train and assess the performance of a deep learning-based network designed to detect, localize, and characterize focal liver lesions (FLLs) in the liver parenchyma on abdominal US images.

Materials and Methods

In this retrospective, multicenter, institutional review board-approved study, two object detectors, Faster region-based convolutional neural network (Faster R-CNN) and Detection Transformer (DETR), were fine-tuned on a dataset of 1026 patients (n = 2551 B-mode abdominal US images obtained between 2014 and 2018). Performance of the networks was analyzed on a test set of 48 additional patients (n = 155 B-mode abdominal US images obtained in 2019) and compared with the performance of three caregivers (one nonexpert and two experts) blinded to the clinical history. The sign test was used to compare accuracy, specificity, sensitivity, and positive predictive value among all raters.

Results

DETR achieved a specificity of 90% (95% CI: 75, 100) and a sensitivity of 97% (95% CI: 97, 97) for the detection of FLLs. The performance of DETR met or exceeded that of the three caregivers for this task. DETR correctly localized 80% of the lesions, and it achieved a specificity of 81% (95% CI: 67, 91) and a sensitivity of 82% (95% CI: 62, 100) for FLL characterization (benign vs malignant) among lesions localized by all raters. The performance of DETR met or exceeded that of two experts and Faster R-CNN for these tasks.

Conclusion

DETR demonstrated high specificity for detection, localization, and characterization of FLLs on abdominal US images. Supplemental material is available for this article.  RSNA, 2022Keywords: Computer-aided Diagnosis (CAD), Ultrasound, Abdomen/GI, Liver, Tissue Characterization, Supervised Learning, Transfer Learning, Convolutional Neural Network (CNN).

Radiomics and Radiogenomics in Evaluation of Colorectal Cancer Liver Metastasis

Colorectal cancer is one common digestive malignancy, and the most common approach of blood metastasis of colorectal cancer is through the portal vein system to the liver. Early detection and treatment of liver metastasis is the key to improving the prognosis of the patients. Radiomics and radiogenomics use non-invasive methods to evaluate the biological properties of tumors by deeply mining the texture features of images and quantifying the heterogeneity of metastatic tumors. Radiomics and radiogenomics have been applied widely in the detection, treatment, and prognostic evaluation of colorectal cancer liver metastases. Based on the imaging features of the liver, this paper reviews the current application of radiomics and radiogenomics in the diagnosis, treatment, monitor of disease progression, and prognosis of patients with colorectal cancer liver metastases.

Ultrasound Image-Based Radiomics: An Innovative Method to Identify Primary Tumorous Sources of Liver Metastases

OBJECTIVES

To develop radiomic models of B-mode ultrasound (US) signatures for determining the origin of primary tumors in metastatic liver disease.

METHODS

A total of 254 patients with a diagnosis of metastatic liver disease were included in this retrospective study. The patients were divided into 3 groups depending on the origin of the primary tumor: group 1 (digestive tract versus non-digestive tract tumors), group 2 (breast cancer versus non-breast cancer), and group 3 (lung cancer versus other malignancies). The patients in each group were allocated to a training or testing set (a ratio of 8:2). The region of interest of liver metastasis was determined through manual differentiation of the tumors, and radiomic signatures were acquired from B-mode US images. Optimal features were selected to develop 3 radiomic models using multiple-dimensionality reduction and classifier screening. The area under the curve (AUC) of the receiver operating characteristic curve was applied to assess each model's performance.

RESULTS

A total of 5936 features were extracted, and 40, 6, and 14 optimal features were sequentially identified for the development of radiomic models for groups 1, 2, and 3, respectively, with training set AUC values of 0.938, 0.974, and 0.768 and testing set AUC values of 0.767, 0.768, and 0.750. The differences in age, sex, and number of liver metastatic lesions varied greatly between the 4 primary tumors (P < .050).

CONCLUSIONS

B-mode US radiomic models could be effective supplemental means to identify the origin of hepatic metastatic lesions (ie, unknown primary sites).

Performance of Ultrasound Techniques and the Potential of Artificial Intelligence in the Evaluation of Hepatocellular Carcinoma and Non-Alcoholic Fatty Liver Disease

Global statistics show an increasing percentage of patients that develop non-alcoholic fatty liver disease (NAFLD) and NAFLD-related hepatocellular carcinoma (HCC), even in the absence of cirrhosis. In the present review, we analyzed the diagnostic performance of ultrasonography (US) in the non-invasive evaluation of NAFLD and NAFLD-related HCC, as well as possibilities of optimizing US diagnosis with the help of artificial intelligence (AI) assistance. To date, US is the first-line examination recommended in the screening of patients with clinical suspicion of NAFLD, as it is readily available and leads to a better disease-specific surveillance. However, the conventional US presents limitations that significantly hamper its applicability in quantifying NAFLD and accurately characterizing a given focal liver lesion (FLL). Ultrasound contrast agents (UCAs) are an essential add-on to the conventional B-mode US and to the Doppler US that further empower this method, allowing the evaluation of the enhancement properties and the vascular architecture of FLLs, in comparison to the background parenchyma. The current paper also explores the new universe of AI and the various implications of deep learning algorithms in the evaluation of NAFLD and NAFLD-related HCC through US methods, concluding that it could potentially be a game changer for patient care.

Deep learning for differentiation of benign and malignant solid liver lesions on ultrasonography

PURPOSE

The ability to reliably distinguish benign from malignant solid liver lesions on ultrasonography can increase access, decrease costs, and help to better triage patients for biopsy. In this study, we used deep learning to differentiate benign from malignant focal solid liver lesions based on their ultrasound appearance.

METHODS

Among the 596 patients who met the inclusion criteria, there were 911 images of individual liver lesions, of which 535 were malignant and 376 were benign. Our training set contained 660 lesions augmented dynamically during training for a total of 330,000 images; our test set contained 79 images. A neural network with ResNet50 architecture was fine-tuned using pre-trained weights on ImageNet. Non-cystic liver lesions with definite diagnosis by histopathology or MRI were included. Accuracy of the final model was compared with expert interpretation. Two separate datasets were used in training and evaluation, one with all lesions and one with lesions deemed to be of uncertain diagnosis based on the Code Abdomen rating system.

RESULTS

Our model trained on the complete set of all lesions achieved a test accuracy of 0.84 (95% CI 0.74-0.90) compared to expert 1 with a test accuracy of 0.80 (95% CI 0.70-0.87) and expert 2 with a test accuracy of 0.73 (95% CI 0.63-0.82). Our model trained on the uncertain set of lesions achieved a test accuracy of 0.79 (95% CI 0.69-0.87) compared to expert 1 with a test accuracy of 0.70 (95% CI 0.59-0.78) and expert 2 with a test accuracy of 0.66 (95% CI 0.55-0.75). On the uncertain dataset, compared to all experts averaged, the model had higher test accuracy (0.79 vs. 0.68, p = 0.025).

CONCLUSION

Deep learning algorithms proposed in the current study improve differentiation of benign from malignant ultrasound-captured solid liver lesions and perform comparably to expert radiologists. Deep learning tools can potentially be used to improve the accuracy and efficiency of clinical workflows.

[Sonographic diagnostics of liver tumors]

Liver tumors are often incidentally found during ultrasound examinations. The decision on further diagnostic imaging depends on the clinical context and the appearance in B mode ultrasound. This review highlights the role of grey scale and contrast-enhanced ultrasound (CEUS) and summarizes the ultrasonographic key features of the most common benign and malignant liver tumors. Conventional grey scale ultrasound is recommended in several guidelines for screening and follow-up of liver tumors in certain risk populations but its ability to characterize liver tumors is limited in most cases. The CEUS has an excellent tolerability and enables liver tumor characterization with a high sensitivity and specificity. The diagnostic value of CEUS is comparable to magnetic resonance imaging. In the case of unclear lesions, inconclusive findings by different imaging methods or if molecular targeted treatment is pursued, ultrasound-guided biopsy is often mandatory. Ultrasound is a rapidly and ubiquitously available method for the detection of liver tumors and CEUS is the only imaging method that enables real-time examination of all contrast phases in the liver. It should therefore be used as the first line imaging method for liver tumor characterization.

Imaging findings of inflammatory pseudotumor-like follicular dendritic cell tumors of the liver: Two case reports and literature review

BACKGROUND

Inflammatory pseudotumor-like follicular dendritic cell (IPT-like FDC) tumors of the liver is an uncommon tumor with extremely low incidence. To date, the radiologic findings of this tumor in multiphase computed tomography (CT) and magnetic resonance imaging (MRI) imaging have not been described.

CASE SUMMARY

Patient 1 is a 31-year-old Chinese female, whose complaining incidentally coincided with the finding of multiple liver masses. In the local hospital, an abdominal enhanced CT found two hypo-dense solid lesions, with heterogeneous sustained hypoenhancement, in the upper segment of the liver’s right posterior lobe. In our hospital, enhanced magnetic resonance imaging (MRI) with hepatocyte-specific contrast agents showed a similar enhanced pattern of lesions with patchy hyperintensity in the hepatobiliary phase (HBP). The patient underwent surgery and recovered well. The final pathology confirmed an IPT-like FDC tumor. No recurrence was found on the regular re-examination. Patient 2 is a 48-year-old Chinese male admitted to our hospital for a huge unexpected hepatic lesion. A dynamic enhanced abdominal CT revealed a huge heterogeneous enhanced solid tumor in the right lobe of the liver with a size of 100 mm × 80 mm, which showed a heterogeneous sustained hypoenhancement. In addition, enlarged lymph nodes were found in the hilum of the liver. This patient underwent a hepatic lobectomy and lymph node dissection. The final pathology confirmed an IPT-like FDC tumor. No recurrence was found upon regular re-examination.

CONCLUSION

When a hepatic tumor shows heterogeneous sustained hypoenhancement with a patchy enhancement during HBP, an IPT-like FDC tumor should be considered in the differential diagnosis.

Liver elastography malignancy prediction score for noninvasive characterization of focal liver lesions

BACKGROUND & AIMS

To analyse elastographic characteristics of focal liver lesions (FLL)s and diagnostic performance of real-time two-dimensional shear-wave elastography (RT-2D-SWE) in order to differentiate benign and malignant FLLs.

METHODS

Consecutive patients diagnosed with FLL by abdominal ultrasound (US) underwent RT-2D-SWE of FLL and non-infiltrated liver by intercostal approach over the right liver lobe. The nature of FLL was determined by diagnostic work-up, including at least one contrast-enhanced imaging modality (MDCT/MRI), check-up of target organs when metastatic disease was suspected and FLL biopsy in inconclusive cases.

RESULTS

We analysed 196 patients (median age 60 [range 50-68], 50.5% males) with 259 FLLs (57 hepatocellular carcinomas, 17 cholangiocarcinomas, 94 metastases, 71 haemangiomas, 20 focal nodular hyperplasia) of which 70 (27%) were in cirrhotic liver. Malignant lesions were stiffer (P < .001) with higher variability in intralesional stiffness (P = .001). The best performing cut-off of lesion stiffness was 22.3 kPa (sensitivity 83%; specificity 86%; positive predictive value [PPV] 91.5%; negative predictive value [NPV] 73%) for malignancy. Lesion stiffness <14 kPa had NPV of 96%, while values >32.5 kPa had PPV of 96% for malignancy. Lesion stiffness, lesion/liver stiffness ratio and lesion stiffness variability significantly predicted malignancy in stepwise logistic regression (P < .05), and were used to construct a new Liver Elastography Malignancy Prediction (LEMP) score with accuracy of 96.1% in validation cohort (online calculator available at http://bit.do/lemps).

CONCLUSION

The comprehensive approach demonstrated in this study enables correct differentiation of benign and malignant FLL in 96% of patients by using RT-2D-SWE.

The Use of Contrast-Enhanced Ultrasonography for the Characterization of Focal Liver Lesions

Focal liver lesions often occur with or without an underlying liver disease. Contrast-enhanced ultrasonography can aid in characterizing liver lesions, potentially avoiding biopsy and computed tomography procedures. Contrast-enhanced ultrasonography has a high sensitivity and specificity for differentiating characteristics of liver lesions compared with noncontrast sonography. The different contrast characteristics aid in differentiating benign and malignant lesions. Malignant lesions tend to have washout of contrast in the venous phases, whereas benign lesions have hyperenhancement during the venous phases. Therefore, contrast-enhanced ultrasonography should be considered an essential component of the diagnostic process for diagnosing and following focal liver lesions.

Algorithm guided outlining of 105 pancreatic cancer liver metastases in Ultrasound

Manual segmentation of hepatic metastases in ultrasound images acquired from patients suffering from pancreatic cancer is common practice. Semiautomatic measurements promising assistance in this process are often assessed using a small number of lesions performed by examiners who already know the algorithm. In this work, we present the application of an algorithm for the segmentation of liver metastases due to pancreatic cancer using a set of 105 different images of metastases. The algorithm and the two examiners had never assessed the images before. The examiners first performed a manual segmentation and, after five weeks, a semiautomatic segmentation using the algorithm. They were satisfied in up to 90% of the cases with the semiautomatic segmentation results. Using the algorithm was significantly faster and resulted in a median Dice similarity score of over 80%. Estimation of the inter-operator variability by using the intra class correlation coefficient was good with 0.8. In conclusion, the algorithm facilitates fast and accurate segmentation of liver metastases, comparable to the current gold standard of manual segmentation.

Liver investigations: Updating on US technique and contrast-enhanced ultrasound (CEUS)

Over the past few years, the cross sectional imaging techniques (Computed Tomography - CT and Magnetic Resonance - MR) have improved, allowing a more efficient study of focal and diffuse liver diseases. Many papers had been published about the results of a routinely clinical use of the dual source/dual energy CT techniques and the use of hepatobiliary contrast agents in MR liver studies. As a consequence, these new improvements have diverted the attention away from the Ultrasound technique and its technical and conceptual evolutions. In these years of disinterest, US and especially Contrast Enhanced Ultrasound (CEUS) have consolidated and grown in their application in clinical routine for liver pathologies. In particular, thanks to the introduction of new, dedicated software packages, CEUS has allowed not only qualitative, but also quantitative analysis of lesion microcirculation, thus opening a new era in the evaluation of lesion characterization and response to therapy. Moreover, the renewed interest in liver elastography, a baseline ultrasound-based imaging modality, has led to the development of a competitive technique to assess liver stiffness and then for the evaluation of the progression towards cirrhosis, and characterization of focal liver lesions, opening the way to avoid, in selected cases, liver biopsy. The aim of this review is to offer an up-to-date overview on the state of the art of clinical applications of US and CEUS in the study of focal and diffuse liver pathologies. Besides, it aims to highlight the emerging role of perfusion techniques in the assessment of local and systemic treatment response and to show how the liver evolution from steatosis to fibrosis can be revealed by elastography.

Interactive Outlining of Pancreatic Cancer Liver Metastases in Ultrasound Images

Ultrasound (US) is the most commonly used liver imaging modality worldwide. Due to its low cost, it is increasingly used in the follow-up of cancer patients with metastases localized in the liver. In this contribution, we present the results of an interactive segmentation approach for liver metastases in US acquisitions. A (semi-) automatic segmentation is still very challenging because of the low image quality and the low contrast between the metastasis and the surrounding liver tissue. Thus, the state of the art in clinical practice is still manual measurement and outlining of the metastases in the US images. We tackle the problem by providing an interactive segmentation approach providing real-time feedback of the segmentation results. The approach has been evaluated with typical US acquisitions from the clinical routine, and the datasets consisted of pancreatic cancer metastases. Even for difficult cases, satisfying segmentations results could be achieved because of the interactive real-time behavior of the approach. In total, 40 clinical images have been evaluated with our method by comparing the results against manual ground truth segmentations. This evaluation yielded to an average Dice Score of 85% and an average Hausdorff Distance of 13 pixels.

Preoperative detection of hepatic metastases from colorectal cancer: Prospective comparison of contrast-enhanced ultrasound and multidetector-row computed tomography (MDCT)

PURPOSE

The goal of this study was to prospectively compare the sensitivity of contrast-enhanced ultrasound (CEUS) with that of multiphase multidetector-row computed tomography (MDCT) in the preoperative detection of hepatic metastases.

MATERIALS AND METHOD

Forty-eight patients, with a mean age of 62years old (range: 43-85years) were prospectively included. All patients underwent CEUS following intravenous administration of 2.4mL of an ultrasound contrast agent (Sonovue(®), Bracco, Milan, Italy) and multiphase MDCT. Intraoperative ultrasound examination (IOUS) was used as the standard of reference.

RESULTS

A total of 158 liver metastases were identified by IOUS, 127 by preoperative MDCT (sensitivity; 80.4%) and 102 by CEUS (sensitivity, 64.5%). The 15.9% difference in sensitivity between CEUS and MDCT was statistically significant (P=0.002). There was a disagreement between IOUS and CEUS in 23 patients (47%) and in 13 patients (27%) between IOUS and MDCT. MDCT identified one or more additional metastases in 10 patients (20%) resulting in a change in the surgical strategy.

CONCLUSION

Based on an unselected patient cohort and using multiphase MDCT, CEUS is significantly inferior to MDCT for the preoperative detection of hepatic metastases of colorectal cancer.

Focal hepatic solid lesions incidentally detected on initial ultrasonography in 542 asymptomatic patients

PURPOSE

The purpose of this study is to evaluate the clinical significance of focal hepatic solid lesions incidentally detected on initial ultrasonography in asymptomatic patients.

METHODS

From January 2009 to December 2009, 2670 initial ultrasonographies were performed in asymptomatic population. Of these 2670 initial examinations, 681 focal hepatic solid lesions in 542 patients (mean 39.4 years, range 23-73 years) were detected. Clinical information, ultrasonography features, and the outcome of these lesions were analyzed.

RESULTS

Six hundred and seventy four lesions (99.0%) in 539 patients (99.4%) were benign, while seven lesions (1.0%) in three patients (0.6%) proved to be malignant. Risk factors significantly associated with malignant focal hepatic solid lesions were known history of malignancy, history of hepatitis, a positive result for the hepatitis B surface antigen, and abnormally elevated tumor markers. No malignancy was identified in patients without any one of these four risk factors. Ultrasonographic features of internal heterogeneous echotexture with peripheral hypoechoic rim showed significant associations with malignancy.

CONCLUSIONS

Focal hepatic solid lesions incidentally detected on initial ultrasonography were rarely malignant, especially in patients without these risk factors. Therefore, the knowledge of these risk factors and US features is important in order to make a differential diagnosis between benign and malignant focal hepatic lesions.

Contrast enhancement ultrasound application in focal liver lesions characterization: a retrospective study about guidelines application (SOCEUS-CEUS survey)

INTRODUCTION

The SOCEUS survey aims to evaluate how contrast-enhanced ultrasound (CEUS) is effectively used in the focal liver lesions characterization.

MATERIALS AND METHODS

In the survey were involved Verona, Brescia and Trieste Radiological Centers and Arezzo and Bologna Non-radiological Centers. Inclusion criteria were liver focal lesion detection at conventional ultrasound and studied by means of CEUS, with or without CT or MRI examinations, done previous or subsequent to CEUS.

RESULTS

1069 forms were collected. Patients with benign lesions, who did not undergo any other studies, were 255/561 (45.5 %). Among patients with diagnosis of hemangioma at CEUS, those who had no other investigations were 129/267 (48.3 %). Patients with malignant lesions who had studies pre-CEUS (CT and/or MRI) were 328/508 (65 %), whereas those who had examinations post-CEUS (CT and/or MRI) were 218/508 (42.9 %). Concordance rate between CEUS and CT investigations pre- and post-CEUS was, respectively, 66 and 89 %. Concordance rate between CEUS and MRI studies pre- and post-CEUS was, respectively, 87.5 and 81.5 %.

CONCLUSION

This study proves contrast-enhanced ultrasound correct application in the involved centers.

Ultrasound imaging of the liver and bile ducts - expectations of a clinician

Since diseases of the liver and bile ducts are common, a clinician is faced by the need to implement an appropriate diagnostic process. It is necessary to apply diagnostic methods that enable appropriate assessment of the most common pathologies of the liver, i.e. fibrosis, steatosis and focal lesions, as well as initial assessment of the bile ducts. These goals can be achieved using ultrasound methods based on conventional sonography, contrast-enhanced sonography and elastography. The assessment of fatty liver and bile duct dilatation using ultrasound reaches satisfactory levels of sensitivity and specificity. The usage of contrast agents enables unambiguous differentiation between benign and malignant focal lesions, frequently allowing them to be identified accurately without the assistance of other imaging modalities. Elastography has enabled reliable assessment of liver fibrosis. Its results are comparable to those of the standard method, i.e. liver biopsy.

Activity-based cost analysis of contrast-enhanced ultrasonography (CEUS) related to the diagnostic impact in focal liver lesion characterisation

PURPOSE

This study was done to assess the clinical-diagnostic impact and cost of contrast-enhanced ultrasound (CEUS) versus computed tomography (CT) and magnetic resonance (MR) imaging in the characterisation of focal liver lesions.

MATERIALS AND METHODS

CEUS with sulphur hexafluoride-filled microbubbles (SonoVue bolus 2.4 ml) was performed in 157 patients with 160 focal liver lesions identified by other diagnostic techniques. CEUS images were obtained during the arterial (15 to 35 s from contrast injection), portal venous (40 to 70 s) and late phase (up to 300 s from microbubble injection). Contrast-enhanced CT was performed with a 64-row multidetector CT. MRI was performed before and after administration of the liver-specific contrast agent gadobenate dimeglumine (Gd-BOPTA). A patient-by-patient activity-based cost analysis was performed.

RESULTS

CEUS led to a change in the diagnostic workup in 131/157 patients (83.4 %) and in the therapeutic workup in 93/157 patients (59.2 %). CEUS allowed for the final diagnosis to be established in 133/157 patients (84.7 %). The full cost of CEUS was lower than that of contrast-enhanced CT and MR imaging.

CONCLUSIONS

CEUS determined a change in the diagnostic and therapeutic workup in the characterisation of focal liver lesions and reduced the full costs of the diagnostic process.

MAIN MESSAGES

• CEUS allows a correct diagnosis in more than 80 % of focal liver lesions. • CEUS has a significant impact on the diagnosis of focal liver lesions. • CEUS examination of focal liver lesions reduces total costs. • Dynamic MR with hepato-specific contrast medium remains the reference standard for lesion characterisation. • CEUS is low-cost, versatile and accurate in the characterisation of focal liver lesions.

Active ultrasound pattern injection system (AUSPIS) for interventional tool guidance

Accurate tool tracking is a crucial task that directly affects the safety and effectiveness of many interventional medical procedures. Compared to CT and MRI, ultrasound-based tool tracking has many advantages, including low cost, safety, mobility and ease of use. However, surgical tools are poorly visualized in conventional ultrasound images, thus preventing effective tool tracking and guidance. Existing tracking methods have not yet provided a solution that effectively solves the tool visualization and mid-plane localization accuracy problem and fully meets the clinical requirements. In this paper, we present an active ultrasound tracking and guiding system for interventional tools. The main principle of this system is to establish a bi-directional ultrasound communication between the interventional tool and US imaging machine within the tissue. This method enables the interventional tool to generate an active ultrasound field over the original imaging ultrasound signals. By controlling the timing and amplitude of the active ultrasound field, a virtual pattern can be directly injected into the US machine B mode display. In this work, we introduce the time and frequency modulation, mid-plane detection, and arbitrary pattern injection methods. The implementation of these methods further improves the target visualization and guiding accuracy, and expands the system application beyond simple tool tracking. We performed ex vitro and in vivo experiments, showing significant improvements of tool visualization and accurate localization using different US imaging platforms. An ultrasound image mid-plane detection accuracy of ±0.3 mm and a detectable tissue depth over 8.5 cm was achieved in the experiment. The system performance is tested under different configurations and system parameters. We also report the first experiment of arbitrary pattern injection to the B mode image and its application in accurate tool tracking.

Characterization of fortuitously discovered focal liver lesions: additional information provided by shearwave elastography

OBJECTIVES

To prospectively assess the stiffness of incidentally discovered focal liver lesions (FLL) with no history of chronic liver disease or extrahepatic cancer using shearwave elastography (SWE).

METHODS

Between June 2011 and May 2012, all FLL fortuitously discovered on ultrasound examination were prospectively included. For each lesion, stiffness was measured (kPa). Characterization of the lesion relied on magnetic resonance imaging (MRI) and/or contrast-enhanced ultrasound, or biopsy. Tumour stiffness was analysed using ANOVA and non-parametric Mann-Whitney tests.

RESULTS

105 lesions were successfully evaluated in 73 patients (61 women, 84%) with a mean age of 44.8 (range: 20‒75). The mean stiffness was 33.3 ± 12.7 kPa for the 60 focal nodular hyperplasia (FNH), 19.7 ± 9.8 k Pa for the 17 hepatocellular adenomas (HCA), 17.1 ± 7 kPa for the 20 haemangiomas, 11.3 ± 4.3 kPa for the five focal fatty sparing, 34.1 ± 7.3 kPa for the two cholangiocarcinomas, and 19.6 kPa for one hepatocellular carcinoma (p < 0.0001). There was no difference between the benign and the malignant groups (p = 0.64). FNHs were significantly stiffer than HCAs (p < 0.0001). Telangiectatic/inflammatory HCAs were significantly stiffer than the steatotic HCAs (p = 0.014). The area under the ROC curve (AUROC) for differentiating FNH from other lesions was 0.86 ± 0.04.

CONCLUSION

SWE may provide additional information for the characterization of FFL, and may help in differentiating FNH from HCAs, and in subtyping HCAs.

KEY POINTS

• SWE might be helpful for the characterization of solid focal liver lesions • SWE cannot differentiate benign from malignant liver lesions • FNHs are significantly stiffer than other benign lesions • Telangiectatic/inflammatory HCA are significantly stiffer than steatotic ones.

Diagnostic performance of contrast-enhanced sonography and acoustic radiation force impulse imaging in solid liver lesions

OBJECTIVES

The purpose of this study was to evaluate the diagnostic performance of contrast-enhanced sonography and acoustic radiation force impulse imaging (ARFI) in differential diagnosis of benign and malignant liver lesions.

METHODS

A total of 156 patients with liver lesions were included in the study. The images from conventional sonography and contrast-enhanced sonography and the shear wave velocity values of the liver lesions were obtained. The diagnostic performance of conventional sonography, contrast-enhanced sonography, and ARFI was assessed by using pathologic examination (needle biopsy or surgery) or clinical imaging inspection as the reference standard.

RESULTS

The sensitivity and specificity of conventional sonography for malignant liver lesions were 57.1% and 43.1%, respectively, and the sensitivity and specificity of ARFI were 81.3% and 74.1%. When using contrast-enhanced sonography for the diagnosis of malignant liver lesions, the sensitivity and specificity were 92.9% and 89.7%. The sensitivity and specificity of contrast-enhanced sonography were significantly higher than those of ARFI and conventional sonography (P < .05).

CONCLUSIONS

The differential diagnostic performance of contrast-enhanced sonography is most predictive of malignant liver lesions. Contrast-enhanced sonography and ARFI have complementary effects in the differential diagnosis of benign and malignant liver lesions.

Malignant focal liver lesions at contrast-enhanced ultrasonography and magnetic resonance with hepatospecific contrast agent

The aim of this study was to compare the diagnostic accuracy of the late phase of CEUS and the hepatobiliary phase of CE-MR with Gd-BOPTA in the characterization of focal liver lesions in terms of benignity and malignancy. A total of 147 solid focal liver lesions (38 focal nodular hyperplasias, 1 area of focal steatosis, 3 regenerative nodules, 8 adenomas, 11 cholangiocarcinomas, 36 hepatocellular carcinomas and 49 metastases) were retrospectively evaluated in a multicentre study, both with CEUS, using sulphur hexafluoride microbubbles (SonoVue, Bracco, Milan, Italy) and CE-MR, performed with Gd-BOPTA (Multihance, Bracco, Milan, Italy). All lesions thought to be malignant were cytohistologically proven, while all lesions thought to be benign were followed up. Sensitivity, specificity, positive (PPV) and negative (NPV) predictive values and accuracy were calculated for the late phase of CEUS and the hepatobiliary phase of CE-MRI, respectively, and in combination. Analysis of data revealed 42 benign and 105 malignant focal liver lesions. We postulated that all hypoechoic/hypointense lesions on the two phases were malignant. The diagnostic errors were 13/147 (8.8%) by CEUS and 12/147 (8.2%) by CE-MR. Sensitivity, specificity, PPV, NPV and accuracy of the late phase of CEUS were 90%, 93%, 97%, 80% and 91%, 93%, 97%, 81% and 92% for the hepatobiliary phase of CE-MRI, respectively. If we considered both techniques, the misdiagnosis diminished to 3/147 (2%) and sensitivity, specificity, PPV, NPV and accuracy were 98%, 98%, 99%, 95% and 98%. The combination of the late phase of CEUS and the hepatobiliary phase of CE-MR in the characterization of solid focal liver lesions in terms of benignity and malignancy is more accurate than the two techniques used separately.

Do radiologists agree on findings in radiographer-acquired sonographic examinations?

OBJECTIVES

Sonographic examinations are usually regarded as observer dependent, but a recently introduced method using documentation with cine loops acquired in a standardized way attempts to address this problem. The aim of this study was to evaluate the intraobserver and interobserver agreement of sonographic liver examinations using strictly standardized examination protocols with cine loop documentation.

METHODS

Ninety-eight outpatients were examined by a radiographer using the standardized method. Three radiologists, each with 10 to 20 years of experience in sonography, reviewed the cine loops retrospectively. After 4 weeks, the review was repeated; the 3 radiologists were blinded to the initial reading. The κ coefficient was used to analyze intraobserver and interobserver agreement, and agreement in percent was also calculated.

RESULTS

The intraobserver agreement was highest for concrements in the gallbladder (κ= 0.91-0.96) and lowest when assessing the need for further examination (κ = 0.38-0.64). For increased liver echogenicity, κ varied between 0.73 and 0.92 and for skip areas between 0.73 and 0.90. The interobserver agreement was also highest for concrements in the gallbladder (κ = 0.84-1.00) and lowest for the need for further examination (κ = -0.12-0.46). For most other findings, substantial intraobserver agreement was found.

CONCLUSIONS

For sonographic examinations performed according to a standardized examination protocol by a radiographer and viewed by an experienced radiologist, good interobserver agreement was found, except for judgments of the need for further examinations.

Hepatocellular carcinoma in cirrhotic patients: prospective comparison of US, CT and MR imaging

OBJECTIVES

To prospectively compare the diagnostic performance of ultrasound (US), multidetector computed tomography (MDCT) and contrast-enhanced magnetic resonance imaging (MRI) in cirrhotic patients who were candidates for liver transplantation.

METHODS

One hundred and forty consecutive patients with 163 hepatocellular carcinoma (HCC) nodules underwent US, MRI and MDCT. Diagnosis of HCC was based on pathological findings or substantial growth at 12-month follow-up. Four different image datasets were evaluated: US, MDCT, MRI unenhanced and dynamic phases, MRI unenhanced dynamic and hepatobiliary phase. Diagnostic accuracy, sensitivity, specificity, PPV and NPV, with corresponding 95 % confidence intervals, were determined. Statistical analysis was performed for all lesions and for three lesion subgroups (<1 cm, 1-2 cm, >2 cm).

RESULTS

Significantly higher diagnostic accuracy, sensitivity and NPV was achieved on dynamic + hepatobiliary phase MRI compared with US, MDCT and dynamic phase MRI alone. The specificity and PPV of US was significantly lower than that of MDCT, dynamic phase MRI and dynamic + hepatobiliary phase MRI. Similar results were obtained for all sub-group analyses, with particular benefit for the diagnosis of smaller lesions between 1 and 2 cm.

CONCLUSIONS

Dynamic + hepatobiliary phase MRI improved detection and characterisation of HCC in cirrhotic patients. The greatest benefit is for diagnosing lesions between 1 and 2 cm.

Hepatocellular carcinoma: diagnostics and screening

Hepatocellular carcinoma (HCC) is the commonest primary hepatic malignancy and the third most common cause of cancer-related death worldwide. Incidence remains highest in the developing world and is steadily increasing across the developed world. The majority of HCC occurs on a background of cirrhosis, principally caused by two major risk factors, chronic hepatitis B and hepatitis C infection. Current diagnostic modalities, of ultrasound and α-fetoprotein, are expensive and lack sensitivity in tumour detection. Early diagnosis is integral to improved survival rates and there have been recent advances in technology that have enabled early identification of the process of hepatocarcinogenesis. This review outlines the epidemiological trends and risk factors for HCC; diagnostic techniques and current guidelines for screening and surveillance; and newer methods of screening.

Characterisation of focal liver lesions with unenhanced and contrast enhanced low MI real time ultrasound: on-site unblinded versus off-site blinded reading

OBJECTIVE

To compare on-site and blinded off-site reading of baseline ultrasound (US) and contrast enhanced ultrasound (CEUS) for classification and characterisation of focal liver lesions.

MATERIALS AND METHODS

99 patients (57 women and 42 men, age range 18-89 years, mean age: 59 years) with 53 malignant and 46 benign liver lesions were studied with unenhanced US followed by contrast enhanced US after injection of 2.4 ml SonoVue® (Bracco, Milano, Italy). Image interpretation was performed on-site with clinical information available by consensus of two readers and off-site by two independent blinded readers at two different centers. Comparison of pre and post contrast scans and of the different readers was performed. Reference examinations were histology, intraoperative US, MRI or CT.

RESULTS

Sensitivity for malignancy improved from 81/89/66% (on-site/off-site reader 1/2) before to 100/96/96% post contrast administration (p<0.05, except for reader 1). Specificity improved from 48/48/54% on baseline US to 89/80/76% on CEUS (p<0.05). Accuracy for specific lesion diagnosis was 62/59/50% pre and 90/77/72% post contrast (p<0.05). Classification and characterisation post contrast were mildly inferior for off-site reading. Agreement between on-site and off-site readers of unenhanced scans was fair (κ=0.29-0.39) while it was good for CEUS (κ=0.63-0.79).

CONCLUSIONS

CEUS improves classification and characterisation of focal liver lesions and interobserver agreement compared to conventional US. Classification and characterisation post contrast were mildly but statistically significantly better for on-site than for off-site reading.

Liver hemangioma and vascular liver diseases in patients with systemic lupus erythematosus

AIM: To investigate whether systemic lupus erythematosus (SLE) is associated with benign focal liver lesions and vascular liver diseases, since these have been occasionally reported in SLE patients.

METHODS: Thirty-five consecutive adult patients with SLE and 35 age- and sex-matched healthy controls were evaluated. Hepatic and portal vein patency and presence of focal liver lesions were studied by colour-Doppler ultrasound, computerized tomography and magnetic resonance were used to refine the diagnosis, clinical data of SLE patients were reviewed.

RESULTS: Benign hepatic lesions were common in SLE patients (54% vs 14% controls, P < 0.0001), with hemangioma being the most commonly observed lesion in the two groups. SLE was associated with the presence of single hemangioma [odds ratios (OR) 5.05; 95% confidence interval (CI) 1.91-13.38] and multiple hemangiomas (OR 4.13; 95% CI 1.03-16.55). Multiple hemangiomas were associated with a longer duration of SLE (9.9 ± 6.5 vs 5.5 ± 6.4 years; P = 0.04). Imaging prior to SLE onset was available in 9 patients with SLE and hemangioma, showing absence of lesions in 7/9. The clinical data of our patients suggest that SLE possibly plays a role in the development of hemangioma. In addition, a Budd-Chiari syndrome associated with nodular regenerative hyperplasia (NRH), and a NRH associated with hepatic hemangioma were observed, both in patients hospitalized for abdominal symptoms, suggesting that vascular liver diseases should be specifically investigated in this population.

CONCLUSION: SLE is associated with 5-fold increased odds of liver hemangiomas, suggesting that these might be considered among the hepatic manifestations of SLE.

Differentiation of focal liver lesions: usefulness of parametric imaging with contrast-enhanced US

PURPOSE

To evaluate whether parametric imaging with contrast material-enhanced ultrasonography (US) is superior to visual assessment for the differential diagnosis of focal liver lesions (FLLs).

MATERIALS AND METHODS

This study had institutional review board approval, and verbal patient informed consent was obtained. Between August 2005 and October 2008, 146 FLLs in 145 patients (63 women, 82 men; mean age, 62.5 years; age range, 22-89 years) were imaged with real-time low-mechanical-index contrast-enhanced US after a bolus injection of 2.4 mL of a second-generation contrast agent. Clips showing contrast agent uptake kinetics (including arterial, portal, and late phases) were recorded and subsequently analyzed off-line with dedicated image processing software. Analysis of the dynamic vascular patterns (DVPs) of lesions with respect to adjacent parenchyma allowed mapping DVP signatures on a single parametric image. Cine loops of contrast-enhanced US and results from parametric imaging of DVP were assessed separately by three independent off-site readers who classified each lesion as benign, malignant, or indeterminate. Sensitivity, specificity, accuracy, and positive and negative predictive values were calculated for both techniques. Interobserver agreement (κ statistics) was determined.

RESULTS

Sensitivities for visual interpretation of cine loops for the three readers were 85.0%, 77.9%, and 87.6%, which improved significantly to 96.5%, 97.3%, and 96.5% for parametric imaging, respectively (P < .05, McNemar test), while retaining high specificity (90.9% for all three readers). Accuracy scores of parametric imaging were higher than those of conventional contrast-enhanced US for all three readers (P < .001, McNemar test). Interobserver agreement increased with DVP parametric imaging compared with conventional contrast-enhanced US (change of κ from 0.54 to 0.99).

CONCLUSION

Parametric imaging of DVP improves diagnostic performance of contrast-enhanced US in the differentiation between malignant and benign FLLs; it also provides excellent interobserver agreement.

A novel Doppler spectral index for differentiating benign from malignant lung tumors

PURPOSE

It has been reported that the resistance index (RI) and pulsatility index (PI) are of limited value in differentiating lung cancers from benign lesions. We hypothesized that a vascular work index (VWI), derived from Doppler spectral waveforms, would yield better results.

METHODS

Forty-one patients were enrolled, 20 of them having malignancies and 21 having benign lesions. The VWI was defined as the square of peak systolic velocity times the time-velocity integral. Maximal VWI, minimal RI, and minimal PI of each tumor were used for analysis.

RESULTS

Significantly higher VWI values were found in malignant tumors compared with benign lesions (p < 0.0001). VWI was shown by analysis of the receiver operating characteristic curve to be a best predictor of lung malignancies than PI and RI (p < 0.05), with a 0.89 (95% confidence interval, 0.80-0.98) area under the receiver operating characteristic curve.

CONCLUSIONS

VWI may be a useful index to help differentiate malignant from benign lung tumors.

Imaging of hepatocellular carcinoma: practical guide to differential diagnosis

Hepatocellular carcinoma (HCC) is most commonly seen in patients with cirrhosis. Criteria for diagnosis include arterial-phase enhancement, venous-phase washout, and a capsule on delayed sequences. Tiny HCC are best detected with magnetic resonance imaging using the new hepatocyte-specific gadolinium agents; otherwise, short-term follow up versus biopsy is considered. Diffuse HCC can be difficult to diagnose because of the inherent heterogeneous hepatic parenchyma in cirrhosis, however, portal vein expansion due to thrombosis is a helpful sign.

Congenital fibrocystic liver diseases

Fibrocystic diseases affecting the liver and often also other organs like the kidneys are a clinically and genetically heterogeneous group of disorders that may present in utero or remain clinically silent into late adulthood. During recent years, substantial progress has been made in unravelling the aetiology with primary cilia playing a central pathogenic role in many if not all of these diseases. The fibrocystogenic process shares some common features including proliferation and dilatation of epithelial bile ducts with concomitant abnormal apoptosis, fluid secretion and extracellular matrix deposition. In this review, we summarise clinical and diagnostic aspects, mechanisms of hepatic cystogenesis, and recent knowledge on potential therapies for these conditions.

Radiologic signs of weapons and munitions: How will noncombatants recognize them?

OBJECTIVE

The purpose of this work was to show the radiologic signs named after weapons and munitions along with their military counterparts to help radiologists recognize these signs, which will allow confident interpretation and diagnosis.

CONCLUSION

Numerous pathologic conditions have classic radiologic manifestations that resemble weapons and ammunition. Most of these signs are highly memorable and easy to recognize. However, the names of the weapons (some of them antique and some not commonly known) may confuse radiologists who are not familiar with the appearance of such weapons as the scimitar, bayonet, or dagger. The value of the signs is reduced if the radiologist is unfamiliar with the appearance of the corresponding weapon.

Characterisation of focal liver lesions undetermined at grey-scale US: contrast-enhanced US versus 64-row MDCT and MRI with liver-specific contrast agent

PURPOSE

The aim of this study was to assess the role of contrast-enhanced ultrasonography (CEUS) in the characterisation of focal liver lesions in comparison with multidetector computed tomography (MDCT) and magnetic resonance imaging (MRI) with liver-specific contrast agent.

MATERIALS AND METHODS

One hundred and eighty-seven focal liver lesions, 91 malignant and 96 benign (mean size 3.2 cm) - proved by biopsy (n=12), histology (n=4), MDCT (n=108), MRI (n=44) MDCT/MRI (n=19) - in 159 patients were studied by CEUS. Two expert radiologists consensually evaluated the contrast-enhancement patterns at CEUS. For each lesion, they assessed: (a) nature (benign, malignant, not assessable), (b) specific diagnosis and (c) need for further radiological evaluation. Sensitivity, specificity, positive and negative predictive values and diagnostic accuracy of CEUS were calculated.

RESULTS

A total of 167/187 (89.3%) lesions were correctly assessed as benign or malignant at CEUS, whereas 14/187 (7.5%) lesions remained undetermined and 6/187 (3.2%) were incorrectly assessed. Sensitivity, specificity, positive and negative predictive values and diagnostic accuracy of CEUS were, respectively, 89%, 89.6%, 89%, 89.6% and 89.3%. The need for further radiological evaluation decreased to 46/187 (24.6%) lesions after CEUS (p<0.001).

CONCLUSIONS

In selected cases, CEUS can be considered an effective alternative to MDCT and MRI and reduce the need for further radiological workup.

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.

MATERIALS AND METHODS

Forty-seven patients with 50 lesions underwent MR imaging and CEUS: 24 focal nodular hyperplasias (FNH), 11 adenomas, 10 haemangiomas, 1 focal fatty change and 4 malignant lesions were identified. Two experienced radiologists randomly reviewed contrast-enhanced MR imaging and CEUS data, and provided the most likely diagnosis. Sensitivity (Se), specificity (Sp), likelihood ratios (LR) and kappa value were calculated.

RESULTS

A histotype diagnosis was obtained in 66-52% with MR imaging and 52-53% with CEUS, respectively, for both readers. Se, Sp and LR for haemangioma were 100-100, 100-100 and 78-78 with MR imaging and 89-89, 100-100 and 68-70 with CEUS; for FNH with MR imaging they were 88-63, 96-100 and 23-34 and 74-67, 88-96 and 6-17 with CEUS. If the diagnosis of haemangioma was uncertain with CEUS, MR imaging always confirmed the diagnosis. If the diagnosis of FNH was uncertain with either CEUS or MR imaging, the other imaging technique confirmed the diagnosis in approximately half the cases.

CONCLUSION

Both CEUS and MR imaging have a high diagnostic performance in incidental focal liver lesions and are complementary when diagnosis is uncertain.

Effect of observer experience in the differentiation between benign and malignant liver tumors after ultrasound contrast agent injection

OBJECTIVE

The purpose of this study was to assess the impact of the observer level of experience on the diagnostic performance of contrast-enhanced ultrasound imaging (CEUS) for differentiation between benign and malignant liver tumors.

METHODS

From a computerized search, we retrospectively identified 286 biopsy-proven liver tumors (105 hepatocellular carcinomas, 48 metastases, 7 intra-hepatic cholangiocarcinomas, 33 liver hemangiomas, and 93 nonhemangiomatous benign lesions) in 235 patients (140 male and 95 female; mean age +/- SD, 56 +/- 11 years) who underwent CEUS after sulfur hexafluoride-filled microbubble injection. The digital cine clips recorded during the arterial (10-35 seconds from injection), portal (50-120 seconds), and late (130-300 seconds) phases were analyzed by 6 independent observers without experience (group 1, observers 1-3) or with 2 to 10 years of experience in CEUS (group 2, observers 4-6). Specific training in the diagnostic and interpretative criteria was provided to the inexperienced observers. Each observer used a 5-point scale to grade diagnostic confidence: 1, definitely benign; 2, probably benign; 3, indeterminate; 4, probably malignant; or 5, definitely malignant on the basis of the enhancement pattern during the arterial phase and enhancement degree during the portal and late phases compared with the liver (hypoenhancement indicating malignant and isoenhancement to hyperenhancement indicating benign).

RESULTS

The analysis of observer diagnostic confidence revealed higher intragroup (kappa = 0.63-0.83) than intergroup (kappa = 0.47-0.63) observer agreement. The experienced observers showed higher diagnostic performance in malignancy diagnosis than did inexperienced observers (overall accuracy: group 1, 63.3%-72.8%; group 2, 75.9%-93.1%; P < .05, chi(2) test).

CONCLUSIONS

The diagnostic performance of CEUS in liver tumor characterization was dependant on the observer's level of experience.