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

Non-invasive diagnosis and follow-up of benign liver tumours

Hepatocellular benign liver tumours are mainly developed on normal liver and include hepatic hemangioma, focal nodular hyperplasia and hepatocellular adenoma from the most frequent to the less frequent. The diagnosis of hepatic hemangioma and of simple hepatic biliary cysts can be performed using non-invasive criteria using liver ultrasonography or contrast enhanced MRI. Most of the time the diagnosis of focal nodular hyperplasia can be achieved using contrast-enhanced ultrasonography or contrast enhanced MRI with an additional value of hepatobiliary contrast-agent in this setting. Rarely, if a doubt persists, a tumour and non-tumour liver biopsy can be required in order to establish the diagnosis. As hepatic hemangioma, simple hepatic biliary cysts and focal nodular hyperplasia are not associated with complications, they don't require any treatments or follow-up. Hepatocellular adenomas are mainly diagnosed at histology on surgical samples or liver biopsy even if some radiological features are highly suggestive of several subtypes of hepatocellular adenomas. Finally, the management of hepatocellular adenomas should be guided according to the tumour size, gender but also to the molecular subtypes.

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.

Scoping review of clinical practice guidelines on the management of benign liver tumours

Objective

Benign liver tumours (BLT) are increasingly diagnosed as incidentalomas. Clinical implications and management vary across and within the different types of BLT. High-quality clinical practice guidelines are needed, because of the many nuances in tumour types, diagnostic modalities, and conservative and invasive management strategies. Yet, available observational evidence is subject to interpretation which may lead to practice variation. Therefore, we aimed to systematically search for available clinical practice guidelines on BLT, to critically appraise them, and to compare management recommendations.

Design

A scoping review was performed within MEDLINE, EMBASE, and Web of Science. All BLT guidelines published in peer-reviewed, and English language journals were eligible for inclusion. Clinical practice guidelines on BLT were analysed, compared, and critically appraised using the Appraisal of Guidelines, Research and Evaluation (AGREE II) checklist regarding hepatic haemangioma, focal nodular hyperplasia (FNH), and hepatocellular adenoma (HCA). Preferred Reporting Items for Systematic Reviews and Meta-Analyses recommendations (PRISMA) for scoping reviews were adhered to.

Results

The literature search yielded unique 367 papers, 348 were excluded after screening of title/abstract, and 16 after full-text screening. Three guidelines were included: the American College of Gastroenterology (ACG; 2014), Brazilian Society of Hepatology (SBH; 2015), and European Association for the Study of the Liver (EASL; 2016). There was no uniformity in the assessment methods for grading and gravity of recommendations between guidelines. Among observed differences were: (1) indications for biopsy in all three tumours; (2) advices on contraceptive pills and follow-up in FNH and HCA; (3) use of an individualised approach to HCA; (4) absence of recommendations for treatment of HCA in men; and (5) approaches to HCA subtype identification on magnetic resonance imaging.

Conclusion

Recognising differences in recommendations can assist in harmonisation of practice standards and identify unmet needs in research. This may ultimately contribute to improved global patient care.

Imaging Characteristics and Management of Infected Hepatic Hemangioma: Case-in Discussion

Hepatic hemangiomas are the most common type of benign liver tumors. We present a case of an infected hepatic hemangioma, which posed a diagnostic challenge. A 43-year-old female presented with right upper quadrant pain after blunt force trauma and intentional weight loss. CT and MRI were done, showing a posterior right lobe liver mass. Imaging characteristics were thought to be suggestive of metastatic disease, with a differential diagnosis of abscess. Drainage and biopsy of the mass revealed Streptococcus sp. infection, and pathology showed a cavernous hemangioma with inflammation. Patients presenting with systemic symptoms and an indeterminate liver mass on imaging should be evaluated for infected hepatic hemangiomas. Biopsy may be needed to rule out cancer. Management may include surgical resection; however, antibiotics and percutaneous drainage can suffice, as in this case.

Focal nodular hyperplasia mimicking hepatocellular adenoma and carcinoma in two cases

Focal nodular hyperplasia (FNH) is a solid benign tumor of the liver, predominantly in young women. A correct diagnosis of FNH is essential for making appropriate clinical decisions and avoiding unnecessary liver resection. Herein, we reported that two male cases with FNH, who initially presented with persistent abdominal discomfort, were misdiagnosed with hepatocellular adenoma (HCA) and hepatocellular carcinoma (HCC) on contrast-enhanced magnetic resonance imaging and computed tomography scans, respectively. After surgery, a histological diagnosis of FNH was finally established. In this paper, we also reviewed the knowledge regarding diagnosis and differential diagnosis of FNH on imaging examinations, which are helpful for avoiding misdiagnoses and guiding clinical interventions.

Shear wave elastography-based ultrasomics: differentiating malignant from benign focal liver lesions

PURPOSE

Ultrasomics is a radiomics technique that extracts high-throughput quantitative data from ultrasound imaging. The aim of this study was to differentiate malignant from benign focal liver lesions (FLLs) using two-dimensional shear wave elastography (2D-SWE)-based ultrasomics.

METHODS

A total of 175 FLLs in 169 patients were prospectively analyzed. The study population was divided into a training cohort (n = 122) and a validation cohort (n = 53). The maxima, minima, mean, and standard deviation of 2D-SWE measurements were expressed in kilopascals (E_max, E_min, E_mean, and E_SD). The ultrasonics technique was used to extract the features from the 2D-SWE images. Support vector machine was used to establish two prediction models: the ultrasomics score (ultrasomics features only) and the combined score (SWE measurements and ultrasomics features). The diagnostic performance of the models in differentiating FLLs was analyzed.

RESULTS

A total of 1044 features were extracted and 15 features were selected. The AUC for the combined score, ultrasomics score, E_max, E_mean, E_min and E_SD were 0.94, 0.91, 0.92, 0.89, 0.67, and 0.89, respectively. The combined score had the best diagnostic performance. The sensitivity, specificity, PPV, NPV, +LR, LR of the combined score were 92.59%, 87.50%, 94.59%, 82.50%, 7.35%, and 0.09%, respectively. The decision curve analysis results showed that when the threshold probability was > 29%, the combined score showed improved benefits for patients compared to using the ultrasomics score and 2D-SWE measurements.

CONCLUSION

The results of this study demonstrated that the combined score had good diagnostic accuracy in differentiating malignant from benign FLLs.

Value of contrast-enhanced ultrasound (CEUS) in Focal Liver Lesions (FLL) with inconclusive findings on cross-sectional imaging

BACKGROUND

Contrast-enhanced ultrasound (CEUS) has been used as an additional imaging technique in order to evaluate focal liver lesions. CEUS is easy and fast to perform, overcomes the limitations of B-mode US.

OBJECTIVE

To evaluate the diagnostic potential of contrast-enhanced ultrasound (CEUS) in focal liver lesions (FLL) with unclear findings on computed tomography (CT) or magnetic resonance imaging (MRI).

METHODS

In this single-center retrospective study, 146 patients with at least one FLL underwent additional CEUS of the liver to clarify inconclusive cross-sectional imaging findings. Ultrasonography was performed using B-mode imaging and CEUS after injection of sulphur hexafluoride microbubbles (second-generation contrast agent) within two months after ceMRI or ceCT and interpreted by an experienced radiologist (EFSUMB level 3). Histopathological reports, long-term follow-up or clinical course served as reference standard.

RESULTS

Thirty-eight of the 146 patients had malignant and 108 benign FLL. Overall, CEUS had 92% sensitivity (95% -CI, 79-97) and 98% specificity (95% -CI, 93-99) with an AUC of 0.95 in correctly characterizing the lesion as malignant or benign. Sensitivity increased to 98% (95% -CI, 96-100) for benign lesions and decreased to 92% (95% -CI, 78-98) for malignant lesions. CEUS showed the highest diagnostical accuracy in lesion <1 cm with an AUC of 1.000, while the lowest accuracy was achieved in lesions >2 cm with an AUC of 0.924 due to a decreasing specificity of 86% (95% -CI, 87-100).

CONCLUSION

CEUS correctly distinguished malignant from benign FLL in cases with inconclusive cross-sectional imaging findings and achieved high levels of diagnostic accuracy. CEUS has added diagnostic value especially in small lesions ≤1 cm while specificity remains limited in larger lesions.

Performance of Contrast-Enhanced Sonography Versus MRI With a Liver-Specific Contrast Agent for Diagnosis of Hepatocellular Adenoma and Focal Nodular Hyperplasia

OBJECTIVE. The purpose of this article is to compare contrast-enhanced sonography (CEUS) with sulfur hexafluoride with MRI with the liver-specific contrast agent gadobenate dimeglumine in the diagnosis of hepatocellular adenoma (HCA) and focal nodular hyperplasia (FNH) in a cohort of consecutive patients. MATERIALS AND METHODS. Patients referred to a tertiary center for hepatobiliary disease who had suspected HCA or FNH on MRI performed with an extracellular gadolinium-based contrast agent underwent a prospective workup including CEUS and MRI with a liver-specific contrast agent. Diagnosis was definite when the findings of CEUS and MRI with a liver-specific contrast agent were concordant; histopathologic examination (HPE) was performed for cases with discordant findings. Descriptive statistics and the association between categoric variables were presented as numbers and percentages and were assessed using the Fisher exact test. The primary analysis was patient based. Sensitivity, specificity, and AUC and predictive values for the diagnosis of HCA and FNH were calculated separately for CEUS and MRI with a liver-specific contrast agent. RESULTS. A total of 181 patients were selected for the first analysis. Findings from CEUS and MRI with a liver-specific contrast agent were concordant for 132 patients (73%) and discordant for 49 (27%). HPE was performed for 26 of the 49 patients with discordant findings (53%), with findings indeterminate for two of these patients, the findings of MRI with a liver-specific contrast agent correct for 21 of the remaining 24 patients (87.5%), and the findings of CEUS correct for three of these 24 patients (12.5%) (p < 0.05). For further analysis, 156 patients with concordant findings or HPE-proven cases were included. For CEUS, the sensitivity and specificity for the diagnosis of HCA and FNH were 85% and 87%, respectively; the ROC AUC value was 0.856; and the positive predictive value and negative predictive value were 79% and 90%, respectively. For MRI with a liver-specific contrast agent, the sensitivity and specificity were 95% each, the ROC AUC value was 0.949, and the positive predictive value and negative predictive value were 92% and 97%, respectively, for the diagnosis of HCA and FNH. CONCLUSION. The findings of CEUS and MRI with a liver-specific contrast agent showed fair agreement for the diagnosis of HCA and FNH. MRI with a liver-specific contrast agent is diagnostically correct significantly more often than CEUS in cases with discordant findings that are HPE proven.

Growth of Focal Nodular Hyperplasia is Not a Reason for Surgical Intervention, but Patients Should be Referred to a Tertiary Referral Centre

Background

When a liver lesion diagnosed as focal nodular hyperplasia (FNH) increases in size, it may cause doubt about the initial diagnosis. In many cases, additional investigations will follow to exclude hepatocellular adenoma or malignancy. This retrospective cohort study addresses the implications of growth of FNH for clinical management.

Methods

We included patients diagnosed with FNH based on ≥2 imaging modalities between 2002 and 2015. Characteristics of patients with growing FNH with sequential imaging in a 6-month interval were compared to non-growing FNH.

Results

Growth was reported in 19/162 (12%) patients, ranging from 21 to 200%. Resection was performed in 4/19 growing FNHs; histological examination confirmed FNH in all patients. In all 15 conservatively treated patients, additional imaging confirmed FNH diagnosis. No adverse outcomes were reported. No differences were found in characteristics and presentation of patients with growing or non-growing FNH.

Conclusion

This study confirms that FNH may grow significantly without causing symptoms. A significant increase in size should not have any implications on clinical management if confident diagnosis by imaging has been established by a tertiary benign liver multidisciplinary team. Liver biopsy is only indicated in case of doubt after state-of-the-art imaging. Resection is deemed unnecessary if the diagnosis is confirmed by multiple imaging modalities in a tertiary referral centre.

Utility of point shear wave elastography in characterisation of focal liver lesions

BACKGROUND

The present study aimed at evaluation of the usefulness of point shear wave elastography (pSWE) in characterization of FLL(s) by quantifying their stiffness.

METHODS

In total, 197 patients (mean age was 56.57 years) with FLL(s) on conventional ultrasound were included. Final diagnoses, confirmed by imaging and/or biopsy whenever possible, included hepatocellular carcinoma (HCC) (n = 143), metastasis (n = 36), hemangioma (n = 16), and focal nodular hyperplasia (n = 2). Stiffness evaluation was performed by pSWE. Stiffness ratio (lesion to background liver) was calculated. ROC analysis was performed to evaluate the diagnostic accuracy of the stiffness value and stiffness ratio and to extract the optimal cutoff values for characterisation of FLL(s).

RESULTS

HCC was significantly softer than its surrounding liver parenchyma [5.43 (3.03) vs. 17.05 (8.53) kPa, p <0.001]. However, the stiffness values for the other examined FLLs were comparable to their surrounding liver parenchyma. No significant difference was detected across different types of metastases or between metastases and surrounding liver (p>0.05). Stiffness ratio was superior to stiffness value in discrimination of HCC from metastasis (AUROC, 0.91 vs. 0.51 respectively).

CONCLUSION

pSWE could provide a complementary information about FLLs especially in differentiation between HCCs from metastases.

Efficacy comparison of multi-phase CT and hepatotropic contrast-enhanced MRI in the differential diagnosis of focal nodular hyperplasia: a prospective cohort study

Background

Different clinical behaviour influences the importance of differentiating focal nodular hyperplasia (FNH) from other focal liver lesions (FLLs). The aim of this study was to compare the efficacy of contrast-enhanced CT and MRI in the diagnosis of FNH.

Methods

157 patients with equivocal FLLs detected in ultrasonography subsequently underwent multi-phase CT and MRI with the use of hepatotropic contrast agent (Gd-BOPTA) in a 1.5 T scanner. Examinations were evaluated by three independent readers. Diagnostic efficacy of different radiological signs of FNH in both CT and MRI was compared and AFROC analysis was performed.

Results

4 hepatocellular adenomas, 95 hepatocellular carcinomas, 98 hemangiomas, 138 metastases and 45 FNHs were diagnosed. In both CT and MRI the radiological sign of the highest accuracy was the presence of the central scar within FNH (0.93 and 0.96 relatively). The sum of two radiological signs in MRI: homogeneous enhancement in hepatic arterial phase (HAP) and enhancing lesion in hepatobiliary phase (HBP) was characterized with high values of sensitivity (0.89), specificity (0.97), PPV (0.82), NPV (0.98) and accuracy (0.96). After inclusion of clinical data into analysis the best discriminating feature in MRI was the presence of enhancing lesion in HBP in patients without cirrhosis. In this regard, efficacy parameters increased to 1.00, 0.99, 0.94, 1.00 and 0.99 accordingly. The area under the curve in AFROC analysis of MRI performance was significantly larger than of CT (p = 0.0145).

Conclusion

Gd-BOPTA-enhanced MRI is a more effective method in the differential diagnosis of FNH than multi-phase CT.

Electronic supplementary material

The online version of this article (10.1186/s12876-017-0719-1) contains supplementary material, which is available to authorized users.

A Model-Based Prediction of the Probability of Hepatocellular Adenoma and Focal Nodular Hyperplasia Based on Characteristics on Contrast-Enhanced Ultrasound

Contrast-enhanced ultrasound (CEUS) is an emerging imaging technique that is increasingly used to diagnose liver lesions. It is of the utmost importance to differentiate between the two most common solid focal liver lesions (i.e., hepatocellular adenoma [HCA] and focal nodular hyperplasia [FNH]), because their management and follow-up differ greatly. The main objective of this study was to determine how frequently the specific CEUS features of HCA and FNH are visible on CEUS and to define their predictive value for discrimination between HCA and FNH. We included 324 CEUS examinations performed on patients with FNH (n = 181) or HCA (n = 143). Patients with HCA and FNH significantly differed with respect to age and CEUS features of steatosis, echogenicity, homogeneity, the presence of a central scar, central artery, arterial enhancement pattern, necrosis or thrombus and enhancement in the late venous phase.

Benign hepatocellular nodules of healthy liver: focal nodular hyperplasia and hepatocellular adenoma

Owing to the progress of imaging techniques, benign hepatocellular nodules are increasingly discovered in the clinical practice. This group of lesions mostly arises in the context of a putatively normal healthy liver and includes either pseudotumoral and tumoral nodules. Focal nodular hyperplasia and hepatocellular adenoma are prototypical examples of these two categories of nodules. In this review we aim to report the main pathological criteria of differential diagnosis between focal nodular hyperplasia and hepatocellular adenoma, which mainly rests upon morphological and phenotypical features. We also emphasize that for a correct diagnosis the clinical context such as sex, age, assumption of oral contraceptives, associated metabolic or vascular disturbances is of paramount importance. While focal nodular hyperplasia is a single entity epidemiologically more frequent than adenoma, the latter is representative of a more heterogeneous group which has been recently and extensively characterized from a clinical, morphological, phenotypical and molecular profile. The use of the liver biopsy in addition to imaging and the clinical context are important diagnostic tools of these lesions. In this review we will survey their systematic pathobiology and propose a diagnostic algorithm helpful to increase the diagnostic accuracy of not dedicated liver pathologists. The differential diagnosis between so-called typical and atypical adenoma and well differentiated hepatocellular carcinoma will also be discussed.

Optimal visualization of focal nodular hyperplasia: quantitative and qualitative evaluation of single and multiphasic arterial phase acquisition at 1.5 T MR imaging

PURPOSE

To evaluate the qualitative and quantitative benefit of multiple arterial phase acquisitions for the depiction of hypervascularity in FNH explored MR imaging using an extracellular contrast agent.

METHODS

Between 2007 and 2014, all patients who underwent MR imaging for the exploration of FNH were included. The protocol included a single or a triple arterial phase ("single" and "triple" group, respectively). Arterial phases were visually divided into four types: (1) angiographic, (2) early, (3) late, and (4) portal. Signal intensity on arterial phase images was visually recorded as intense, moderate, or low for each lesion. Lesion-to-liver contrast (LLC) and relative lesion enhancement (RE) were calculated and compared between the two groups using the Mann-Whitney test.

RESULTS

Thirty-five women were included (mean 45-year old, range 20-66), with 50 FNH (mean size 30 mm). Single and triple groups included 20 patients (30 FNH) and 15 patients (20 FNH), respectively. Signal intensity was intense in all lesions in the triple group and in 22/30 (73%) in the single group (p = 0.041). Intense signals were more frequently found in the early arterial phase (p < 0.001). RE was not significantly different (1.78 ± 0.84 vs. 1.98 ± 1.81 p = 0.430, in the single and triple groups, respectively) but LLC was significantly higher in the triple group (0.32 ± 0.10 vs. 0.22 ± 0.10, p = 0.005). LLC was significantly higher in the first two arterial phases in the triple group (p < 0.001).

CONCLUSION

Acquisition of three arterial phases improves the visualization of hypervascularity of FNH, as lesions show high visual signal intensity and contrast. Optimal visualization is obtained in the early arterial phase.

Focal liver lesions found incidentally

Incidentally found focal liver lesions are a common finding and a reason for referral to hepatobiliary service. They are often discovered in patients with history of liver cirrhosis, colorectal cancer, incidentally during work up for abdominal pain or in a trauma setting. Specific points should considered during history taking such as risk factors of liver cirrhosis; hepatitis, alcohol consumption, substance exposure or use of oral contraceptive pills and metabolic syndromes. Full blood count, liver function test and tumor markers can act as a guide to minimize the differential diagnosis and to categorize the degree of liver disease. Imaging should start with B-mode ultrasound. If available, contrast enhanced ultrasound is a feasible, safe, cost effective option and increases the ability to reach a diagnosis. Contrast enhanced computed tomography should be considered next. It is more accurate in diagnosis and better to study anatomy for possible operation. Contrast enhanced magnetic resonance is the gold standard with the highest sensitivity. If doubt still remains, the options are biopsy or surgical excision.

Ultrasound features of hepatocellular adenoma and the additional value of contrast-enhanced ultrasound

BACKGROUND

Hepatocellular adenoma (HCA) is a rare benign tumor of the liver. It is of clinical importance to differentiate HCA from other liver tumors, especially hepatocellular carcinoma (HCC). This study aimed to evaluate the characteristic features of HCA by conventional ultrasound and contrast-enhanced ultrasound (CEUS) findings.

METHODS

Twenty-six patients (10 males and 16 females; mean age 36.2+/-5.0 years) with 26 histopathologically proven HCAs were retrospectively identified. According to the maximum diameter of HCAs, they were divided into three groups: <30 mm, 30-50 mm, and >50 mm. Ultrasound examinations were performed with C5-2 broadband curved transducer of Philips iU22 unit (Philips Bothell, WA, USA). For each lesion, a dose of 2.4 mL SonoVue® (Bracco Imaging Spa, Milan, Italy) was injected as a quick bolus into the cubital vein. Lesions' echogenicity, color-Doppler flow imaging and contrast enhancement patterns were recorded.

RESULTS

Grayscale ultrasound revealed that most of HCAs were hypoechoic (73.1%, 19/26). Spotty calcifications were detected in 26.9% (7/26) of the lesions. Color-Doppler flow imaging detected centripetal bulky color flow in 46.2% (12/26) of the HCAs. CEUS showed that 73.1% (19/26) of the HCAs displayed as rapid, complete and homogenous enhancement, and 53.8% (14/26) showed decreased contrast enhancement in the late phase. There was no significant difference in enhancement patterns among different sizes of HCAs (P>0.05). Centripetal enhancement with subcapsular tortuous arteries was common in larger HCAs.

CONCLUSIONS

CEUS combined with grayscale and color-Doppler flow imaging helped to improve preoperative diagnosis of HCAs. The characteristic imaging features of HCAs included: rapid homogeneous enhancement and slow wash-out pattern on CEUS; heterogeneous echogenicity on grayscale ultrasound; and centripetal enhancement with subcapsular tortuous arteries in large HCAs.

Is Non-Contrast CT Adequate for the Evaluation of Hepatic Metastasis in Patients Who Cannot Receive Iodinated Contrast Media?

Objective

To evaluate the appropriateness of follow-up with only non-enhanced CT (NECT) in patients with gastrointestinal cancer.

Subjects and Methods

This retrospective study included 323 patients with colorectal and gastric cancer who underwent two consecutive CT examinations (CT1 and CT2), including non-contrast and portal venous phase CT images, with an interval of 1 year. Patients were divided into 2 groups: Group A included patients with no hepatic metastasis on CT1 and with or without newly developed metastasis on CT2 to evaluate the diagnostic performance of NECT for detecting newly developed hepatic metastasis; Group B included patients with known hepatic metastasis both on CT1 and CT2 to evaluate the accuracy of NECT for the assessment of hepatic metastasis based on RECIST criteria (version 1.1). Contrast-enhanced CT (CECT) images were considered as reference standards.

Results

Group A included 172 patients (M:F = 107:65; mean age, 62.6 years). Among them, 57 patients had 95 metastases (mean size, 2.2 ± 1.3 cm). Per patient and per lesion sensitivity for diagnosing newly developed hepatic metastasis was 56.1–66.7% and 52.6–56.8%, respectively. In terms of small metastases (<1.5 cm), per lesion sensitivity was significantly decreased to 28.1–34.4% (P < 0.05). Metastasis size measurements were significantly smaller on NECT (P < 0.001) compared with reference standards. In Group B, the accuracy of response evaluation based on RECIST criteria was 65.6–72.2%.

Conclusions

NECT showed inadequate diagnostic performances in both detecting newly developed hepatic metastasis and evaluating the response of hepatic metastasis based on RECIST criteria.

Diagnostic workup of liver lesions: too long time with too many examinations

OBJECTIVE

Liver mass lesions are often detected incidentally. Subsequent imaging examinations and surveillance are not only expensive, but may also cause unnecessary concern to patients. The aim of this study was to evaluate retrospectively the possible delay in acquiring the diagnosis of liver mass lesions, and to estimate the number of imaging examinations performed during the diagnostic workup.

PATIENTS AND METHODS

The study comprised 200 patients with liver mass lesion of unknown etiology. The time needed from referral to final diagnosis was assessed. All imaging examinations and biopsy findings (if available) during the diagnostic workup were recorded.

RESULTS

Out of the 200 lesions, 133 were malignant, 65 with hepatocellular cancer and 26 with cholangiocarcinoma. All except one were diagnosed within 8 weeks. Of the 67 benign lesions, there were 20 focal nodular hyperplasias and 20 hemangiomas. For the benign lesions, in 37% the diagnostic workup took >8 weeks. Repeated examinations were more common in benign lesions; but often redundant in both benign and malignant conditions in retrospect analysis.

CONCLUSIONS

To confirm the diagnosis, benign lesions required more follow-up time and more repeated imaging examinations than malignant ones. A long surveillance for liver mass lesions in fear of malignancy seems not to be necessary, since virtually all malignant lesions were diagnosed within 8 weeks. Evaluating all lesions in a multidisciplinary team right from the beginning is advocated by a prospective study design.

Diagnosis and management of solid benign liver lesions

More and more asymptomatic benign liver tumours are discovered incidentally and can be divided into regenerative lesions and true neoplastic lesions. The most common regenerative lesions include hemangioma, focal nodular hyperplasia and inflammatory pseudotumours of the liver. Neoplastic lesions include hepatocellular adenomas and angiomyolipomas. Regenerative lesions rarely increase in volume, do not yield a higher risk of complications and usually do not require treatment. By contrast, hepatocellular adenomas and angiomyolipomas can increase in volume and are associated with a risk of complications. Large hepatocellular adenomas (>5 cm in diameter) are undoubtedly associated with a risk of bleeding and malignant transformation, particularly the inflammatory (also known as telangiectatic) and β-catenin mutated subtypes. Accurate diagnosis needs to be obtained to select patients eligible for surgical resection. MRI has markedly improved diagnosis and can identify the major hepatocellular adenomas subtypes. The use of biopsy results to inform the indication for resection remains questionable. However, when diagnosis remains uncertain after imaging, percutaneous biopsy could help improve diagnostic accuracy.

Imaging of benign hepatocellular lesions: current concepts and recent updates

Focal nodular hyperplasia (FNH) and hepatocellular adenoma (HCA) are a variety of solid lesions mostly found in the absence of underlying chronic liver disease in young patients. HCA is no longer to be considered as a unique lesion but as a recollection of different entities sharing common points but most of all separated by different typical morphological aspects. Accurate diagnosis is of clinical importance as the management is most of the time conservative for FNH, whereas HCAs expose patients to hemorrhage and malignant transformation, and may lead to a more invasive treatment, mainly surgical resection. Moreover, the different HCA subtypes expose to different risks of complication. The best imaging techniques for the differentiation between FNH and HCAs and for the subtyping of HCAs are contrast-enhanced ultrasound (CEUS) and magnetic resonance imaging (MRI), as specific combinations of imaging features have been associated with the different lesions. They should be considered as complementary examinations. Atypical or multiple lesions, lesions containing fat or presence of an associated steatosis represent diagnostic challenges. Recently, MR hepatospecific contrast agents have been shown to be useful. Emergent elastography techniques might also be helpful in the near future. Biopsy should always be performed in case of uncertain diagnosis to reach a final diagnosis and avoid unnecessary invasive treatment.

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.

Contrast-enhanced ultrasonography: advance and current status in abdominal imaging

In the field of contrast-enhanced ultrasonography (US), contrast agents are classified as either first- or second-generation agents depending on the gas within the microbubbles. In the case of first-generation contrast agents, a high-mechanical-index technique is used and only intermittent scanning is possible due to the early destruction of the microbubbles during the scanning. The use of second-generation contrast agents in a low-mechanical-index technique enables continuous scanning. Besides the detection and characterization of focal liver lesions, contrastenhanced US is helpful in the monitoring of radiofrequency ablation therapy and in the targeting step of an US-guided biopsy. Recently, there has been a demand for new criteria to evaluate the treatment response obtained using anti-angiogenic agents because morphologic criteria alone may not reflect the treatment response of the tumor and contrast-enhanced US can provide quantitative markers of tissue perfusion. In spite of the concerns related to its cost-effectiveness, contrast-enhanced US has the potential to be more widely used as a complimentary tool or to substitute the current imaging modalities in some occasions.

Differentiation of focal nodular hyperplasia from hepatocellular adenomas with low-mechanical-index contrast-enhanced sonography (CEUS): effect of size on diagnostic confidence

PURPOSE

The purpose of this study was to assess the diagnostic performance of contrast-enhanced sonography (CEUS) for the differentiation of focal nodular hyperplasia (FNH) from hepatocellular adenoma (HCA) according to lesion size.

MATERIALS AND METHODS

Forty patients with a definite diagnosis of FNH or HCA who underwent CEUS were included in this institutional review board (IRB)-approved study. A total of 43 FNHs and 20 HCAs, including 15 inflammatory HCAs and five unclassified HCAs, were analysed. Two radiologists reviewed the diagnostic CEUS parameters separately and in consensus, including the presence or absence of centrifugal filling and central vessels. The sensitivity (Se), specificity (Sp), and inter-observer confidence (Kappa) of CEUS diagnostic parameters were assessed.

RESULTS

Inter-observer agreement of CEUS for FNH diagnosis was high (kappa = 0.81) with an overall Se of 67.4% [29/43 (CI 95%: 51.4-80.1 %)] and an Sp of 100% [20/20 (CI 95%: 81-100%)]. Significantly higher Se figures were found for lesions ≤ 35 mm than for lesions > 35 mm [respectively, 93 % (28/30) (CI 95%: 77.6-99.2) vs. 7.7% (1/13) (CI 95%: 0.2-36%), p = 0.002] with unchanged specificity.

CONCLUSION

CEUS is highly specific for the diagnosis of FNH, with very good inter-observer agreement, whatever the size, but its sensitivity is significantly reduced in diagnosing lesions larger than 35 mm.

KEY POINTS

• CEUS is highly specific for the diagnosis of FNH, regardless of lesion size • CEUS shows reduced sensitivity in diagnosing FNH lesions larger than 35 mm • The filling patterns of hepatocellular adenomas are not affected by lesion size.

Contrast-enhanced ultrasound of focal nodular hyperplasia: a matter of size

OBJECTIVES

To assess the contrast-enhanced ultrasound (CEUS) frequencies of centrifugal enhancement, spoke-wheel sign and central scar in focal nodular hyperplasia (FNH) as a function of lesion size.

METHODS

Ninety-four FNHs were retrospectively reviewed to assess their largest diameter and enhancement pattern, including centrifugal enhancement from one central artery, spoke-wheel sign, diffuse or centripetal enhancement, central scar and late-phase washout.

RESULTS

Mean FNH-lesion size was 3.7 ± 2.1 cm. Only 43.6 % of FNHs had centrifugal enhancement, with a spoke-wheel pattern (23.4 %) or without (20.2 %), while 56.4 % showed diffuse or centripetal enhancement. Centrifugal enhancement was observed in 73.9 % of FNHs ≤3.1 cm and 14.6 % of FNHs >3.1 cm (P < 10(-4)). Size and frequency of centrifugal enhancement were negatively correlated (r = -0.57, P < 10(-4)). The spoke-wheel pattern was also seen more frequently in smaller (37 %) than in larger FNHs (10.4 %) (P < 10(-3)). Late-phase washout was described in 5.3 % of FNHs and was not size-dependent. Lesions with a central scar were larger than those without, respectively, 5.7 ± 1.7 and 3.6 ± 2.0 cm (P = 0.012).

CONCLUSIONS

Typical centrifugal enhancement yielding a confident FNH diagnosis is seen significantly more frequently when the lesion is ≤3.1 cm.

KEY POINTS

• CEUS yields confident diagnoses of FNHs ≤3.1 cm • The larger the FNH, the lower the diagnostic sensitivity of CEUS • Final diagnosis of FNHs >3.1 cm should be obtained with MRI not CEUS.

Indeterminate solid hepatic lesions identified on non-diagnostic contrast-enhanced computed tomography: assessment of the additional diagnostic value of contrast-enhanced ultrasound in the non-cirrhotic liver

OBJECTIVE

To assess the additional diagnostic value of contrast-enhanced ultrasound (CEUS) in the characterization of indeterminate solid hepatic lesions identified on non-diagnostic contrast-enhanced computed tomography (CT).

METHODS

Fifty-five solid hepatic lesions (1-4 cm in diameter) in 46 non-cirrhotic patients (26 female, 20 male; age±SD, 55±10 years) underwent CEUS after being detected on contrast-enhanced CT which was considered as non-diagnostic after on-site analysis. Two blinded independent readers assessed CT and CEUS scans and were asked to classify retrospectively each lesion as a malignant or benign based on reference diagnostic criteria for the different hepatic lesion histotypes. Diagnostic accuracy and confidence (area--Az--under ROC curve) were assessed by using gadobenate dimeglumine-enhanced magnetic resonance (MR) imaging (n=30 lesions), histology (n=7 lesions), or US follow-up (n=18 lesions) as the reference standards.

RESULTS

Final diagnoses included 29 hemangiomas, 3 focal nodular hyperplasias, 1 hepatocellular adenoma, and 22 metastases. The additional review of CEUS after CT images improved significantly (P<.05) the diagnostic accuracy (before vs after CEUS review=49% [20/55] vs 89% [49/55]--reader 1 and 43% [24/55] vs 92% [51/55]--reader 2) and confidence (Az, 95% Confidence Intervals before vs after CEUS review=.773 [.652-.895] vs .997 [.987-1]--reader 1 and .831 [.724-.938] vs .998 [.992-1]--reader 2).

CONCLUSIONS

CEUS improved the characterization of indeterminate solid hepatic lesions identified on non-diagnostic contrast-enhanced CT by identifying some specific contrast enhancement patterns.

Characterization of incidental liver lesions: comparison of multidetector CT versus Gd-EOB-DTPA-enhanced MR imaging

As a result of recent developments in imaging modalities and wide spread routine medical checkups and screening, more incidental liver lesions are found frequently on US these days. When incidental liver lesions are found on US, physicians have to make a decision whether to just follow up or to undergo additional imaging studies for lesion characterization. In order to choose the next appropriate imaging modality, the diagnostic accuracy of each imaging study needs to be considered. Therefore, we tried to compare the accuracy of contrast-enhanced multidetector CT (MDCT) and Gd-EOB-DTPA-enhanced MRI for characterization of incidental liver masses. We included 127 incidentally found focal liver lesions (94 benign and 33 malignant) from 80 patients (M∶F = 45∶35) without primary extrahepatic malignancy or chronic liver disease. Two radiologists independently reviewed Gd-EOB-DTPA-enhanced MRI and MDCT. The proportion of confident interpretations for differentiation of benign and malignant lesions and for the specific diagnosis of diseases were compared. The proportion of confident interpretations for the differentiation of benign and malignant lesions was significantly higher with EOB-MRI(94.5%-97.6%) than with MDCT (74.0%-92.9%). In terms of specific diagnosis, sensitivity and accuracy were significantly higher with EOB-MRI than with MDCT for the diagnosis of focal nodular hyperplasia (FNH) and focal eosinophilic infiltration. The diagnoses of the remaining diseases were comparable between EOB-MRI and MDCT. Hence, our results suggested that Gd-EOB-MRI may provide a higher proportion of confident interpretations than MDCT, especially for the diagnosis of incidentally found FNH and focal eosinophilic infiltration.

Liver lesions discovered incidentally on ultrasound: evaluation of reader ability to characterize lesions on MRI without intravenous contrast

RATIONALE AND OBJECTIVES

Liver lesions incidentally discovered on ultrasound (US) are often further evaluated with magnetic resonance imaging (MRI). The purpose of this study is to evaluate the added effectiveness of contrast-enhanced MRI, compared to noncontrast MRI, to correctly guide management of liver lesions incidentally identified on ultrasound in patients with low pretest probability of malignancy. We conducted the evaluation using a multireader study.

MATERIALS AND METHODS

Liver MRI studies ordered to evaluate incidental liver US lesions were selected for analysis. Patients with no prior history of cancer or chronic liver disease who had 2 years of clinical follow-up (72 patients) were selected to ensure low pretest probability of malignancy and adequate follow-up to establish proof of diagnosis. Fifty of these studies were randomly selected and analyzed by two abdominal radiologists. In the initial interpretation session, only nonenhanced images were reviewed; after 6 weeks, the complete exam including the contrast enhanced images were viewed. Differences in interpretation between the noncontrast and contrast enhanced reading sessions were assessed.

RESULTS

Sixty-nine patients (95.8%) had no abnormalities, benign masses, or hepatic steatosis accounting for the ultrasound findings. One patient was newly diagnosed with hereditary hemochromatosis, and 2 patients were newly diagnosed with metastatic disease. The most likely diagnosis changed for 15 of the lesions described by reader A, and 16 by reader B. The majority of these changes (26/31 lesions, 84%) were from one benign entity to another. Five of 31 (16%) of the changes involved that of a benign entity to a malignant one. Reader A recommended additional contrast enhanced imaging in 13/50 (26%) patients; reader B, 9/50 (18%) patients. After viewing the nonenhanced images, both readers recommended that all patients with eventual malignancies return for contrast administration and/or biopsy. After viewing the contrast-enhanced imaging, both readers accurately diagnosed all malignancies. Patient-based analysis receiver operating characteristic curves demonstrated no significant difference between the enhanced and noncontrast limbs of the study, and no significant difference between readers.

CONCLUSION

Most of the changes in lesion detection and characterization made after contrast administration were clinically insignificant. In the lesions in which clinically important differences were made, both radiologists recommended additional imaging or biopsy that would have eventually led to the correct diagnosis. None of the patients with malignancy was categorized as completely benign either on noncontrast or contrast-enhanced imaging. This supports the utility of initially performing a noncontrast examination in a population with a low pretest probability of malignancy, especially those in whom gadolinium administration is contraindicated.

Comparison of Kupffer-phase Sonazoid-enhanced sonography and hepatobiliary-phase gadoxetic acid-enhanced magnetic resonance imaging of hepatocellular carcinoma and correlation with histologic grading

OBJECTIVES

To determine the relative wash-out of hepatocellular carcinomas and dysplastic nodules using Kupffer-phase sonography with Sonazoid (Daiichi-Sankyo, Tokyo, Japan) enhancement and hepatobiliary-phase gadoxetic acid-enhanced magnetic resonance imaging (MRI) in the evaluation of the histopathologic grades of individual nodules.

METHODS

This retrospective study included 66 consecutive patients with 78 histologically confirmed hepatocellular carcinomas and dysplastic nodules. In patients with carcinomas, 33 were well differentiated; 29 were moderately differentiated; and 11 were poorly differentiated; and there were 5 dysplastic nodules. All patients underwent both gadoxetic acid-enhanced MRI and Sonazoid-enhanced sonography. The interval between the two imaging examinations was less than 30 days. Six radiologists independently reviewed both images and rated the degree of relative wash-out between the tumorous and nontumorous areas on Kupffer- and hepatobiliary-phase images using a continuous rating scale. We compared these results with the histopathologic grade of each nodule, and the results were then analyzed with multireader multicase receiver operating characteristic analysis.

RESULTS

The average Kupffer-phase (P < .001) and hepatobiliary-phase (P = .004) rating scores increased as the carcinomas became less differentiated (Kruskal-Wallis test). The diagnostic accuracies of the average area under the receiver operating characteristic curve, which were estimated using the confidence levels of the relative wash-out of the Kupffer- and hepatobiliary-phase images, were 0.705 and 0.785 for dysplastic nodules versus well-, moderately, and poorly differentiated carcinomas (P = .517), 0.791 and 0.687 for dysplastic nodules and well-differentiated carcinomas versus moderately and poorly differentiated carcinomas (P = .093), and 0.871 and 0.716 for dysplastic nodules and well-and moderately differentiated carcinomas versus poorly differentiated carcinomas (P = .005), respectively.

CONCLUSIONS

Kupffer-phase Sonazoid-enhanced sonography and hepatobiliary-phase gadoxetic acid-enhanced MRI may be useful in estimating the histologic grade, although Kupffer-phase Sonazoid-enhanced sonography may be more accurate in distinguishing hepatocellular carcinomas, especially moderately and poorly differentiated types.

Current and potential renal applications of contrast-enhanced ultrasound

The combination of microbubble technology and complementary ultrasound techniques has resulted in the development of contrast-enhanced ultrasound (CEUS) and, although initial clinical applications largely focussed on the liver, these are now becoming more diverse. With regard to the kidney, it is a safe, well-tolerated, and reproducible technique, and in selected cases, can obviate the need for computed tomography or magnetic resonance imaging. A clear advantage is the absence of nephrotoxicity. With respect to the current and potential renal applications, it is a useful technique in the evaluation of pseudotumours, acute pyelonephritis, renal tumours, cystic lesions, vascular insults, and renal transplantation. It may also be of value for monitoring the kidney following anti-angiogenic treatment or nephron-sparing interventional techniques for renal tumours. Assessment of microvascular perfusion using time-intensity curves is also likely to have further far-reaching applications in the kidney as well as other organs.

[Benign focal hepatic lesions]

A profound knowledge of the various benign focal hepatic lesions and selection of the most suitable radiological examination modality is essential for achieving an accurate characterization of a hepatic lesion and in turn will determine the further patient management. This will avoid unnecessary agitation to both patient and the referring clinician and limits time-consuming, costly and risky biopsies to an absolute minimum. The following article will discuss the typical and atypical appearances of the most frequent and clinically relevant benign focal hepatic lesions with ultrasound, computed tomography and magnetic resonance imaging.

Assessment of arterial hypervascularity of hepatocellular carcinoma: comparison of contrast-enhanced US and gadoxetate disodium-enhanced MR imaging

OBJECTIVE

To compare contrast-enhanced (CE) ultrasound with gadoxetate disodium-enhanced magnetic resonance (MR) imaging in the assessment of arterial hypervascularity of hepatocellular carcinoma (HCC) and dysplastic nodule (DN), with CT during hepatic arteriography (CTHA) as the reference standard.

METHODS

This study included 54 consecutively diagnosed patients, with 57 histologically confirmed HCCs and 3 DNs (high-grade). All patients underwent CE ultrasound, gadoxetate disodium-enhanced MR imaging and CTHA. Two trained diagnostic radiologists interpreted the CTHA images and rated the degree of intratumoral arterial vascularity by consensus using a five-point confidence scale as the reference standard. In the observer study, the degrees of vascularity on CE ultrasound and gadoxetate disodium-enhanced MR images were qualitatively analysed by four independent readers using a five-point confidence scale. Diagnostic accuracy was analysed by receiver-operating characteristic (ROC) analysis.

RESULTS

The diagnostic accuracies of the average area under the ROC curve (AUC) were significantly greater with CE ultrasound (average AUC: 0.94; 95% confidence interval [CI]: 0.88-1.00) than with gadoxetate disodium-enhanced MR imaging (average AUC 0.84, 95% CI 0.74-0.93, P = 0.0014).

CONCLUSION

Contrast-enhanced ultrasound yields a significantly higher AUC value than gadoxetate disodium-enhanced MR imaging in the assessment of arterial hypervascularity of HCC and DN.

KEY POINTS

• Arterial hypervascularity is an important feature determining treatment options in hepatocellular carcinoma. • It can be assessed by contrast-enhanced (CE) ultrasound or magnetic resonance (MR) imaging. • CE ultrasound was more accurate than Gd-EOB-DTPA MRI in assessing intratumoral vascularity. • Hypovascular hepatic nodules should be further investigated using CE ultrasound.

Can a decision-making model be justified in the management of hepatocellular adenoma?

During recent years, there was a great development in the area of hepatocellular adenomas (HCA), especially regarding the pathological subtype classification, radiological imaging and management during pregnancy. This review discusses the current knowledge about diagnosis and treatment modalities of HCA and proposes a decision-making model for HCA. A Medline search of studies relevant to epidemiology, histopathology, complications, imaging and management of HCA lesions was undertaken. References from identified articles were hand-searched for further relevant articles.

Evaluation of focal hepatic lesions with ultrasound contrast agents

Ultrasound contrast agents have gained wide acceptance for the detection and characterization of focal liver lesions. This pictorial essay reviews the growing body of evidence that supports the use of modern ultrasound contrast agents and illustrates the enhancement characteristics of commonly encountered focal liver lesions. Pathologies discussed include metastases, hepatocellular carcinomas, focal nodular hyperplasia, hepatocellular adenomas, hemangiomas, abscesses, complex cysts, and focal fatty deposition.

Consensus report of the 4th International Forum for Gadolinium-Ethoxybenzyl-Diethylenetriamine Pentaacetic Acid Magnetic Resonance Imaging

This paper reports on issues relating to the optimal use of gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid magnetic resonance imaging (Gd-EOB-DTPA MR imaging) together with the generation of consensus statements from a working group meeting, which was held in Seoul, Korea (2010). Gd-EOB-DTPA has been shown to improve the detection and characterization of liver lesions, and the information provided by the hepatobiliary phase is proving particularly useful in differential diagnoses and in the characterization of small lesions (around 1-1.5 cm). Discussion also focused on advances in the role of organic anion-transporting polypeptide 8 (OATP8) transporters. Gd-EOB-DTPA is also emerging as a promising tool for functional analysis, enabling the calculation of post-surgical liver function in the remaining segments. Updates to current algorithms were also discussed.

Indeterminate focal liver lesions incidentally discovered at gray-scale US: role of contrast-enhanced sonography

OBJECTIVES

to assess the role of contrast-enhanced ultrasound (CEUS) in the characterization of focal liver lesions (FLLs) incidentally discovered but indeterminate at gray-scale ultrasound (US).

MATERIALS AND METHODS

one hundred forty-two consecutive patients with 174 FLLs (169 benign and 5 malignant) incidentally discovered but indeterminate at gray-scale US, underwent CEUS after the administration of SonoVue. Two readers independently reviewed CEUS scans and: (1) classified each lesion as malignant or benign on a 5-point scale of confidence by means of definite diagnostic criteria; (2) provided if possible a specific diagnosis; (3) were requested if further imaging was needed for lesion characterization. Sensitivity, specificity, and areas under the receiver-operating characteristic curve (Az) as well as interobserver agreement were calculated.

RESULTS

at CEUS, both readers correctly differentiated benign from malignant lesions in 168 of 174 (96.5%) cases (P < 0.0001). A specific correct diagnosis was provided in 123 of 174 (70.7%) and 127 of 174 (72.9%) cases for reader 1 and 2, respectively (P < 0.0001). A further imaging study to characterize the lesion after CEUS was requested in 67 cases (38.5%) for reader 1 (P < 0.001) and 46 cases (26.4%) for reader 2 (P < 0.001). Receiver-operating characteristic analysis after CEUS revealed Az value of 1 for both readers and sensitivity and specificity values of 100% and 97.04% for reader 1 and 100% and 96.45 for reader 2 respectively (P < 0.0001). Inter-reader agreement at CEUS was good (weighted k = 0.779).

CONCLUSION

CEUS improves the diagnostic performance of radiologists in the characterization of indeterminate FLLs incidentally discovered at US and reduces the need for further radiologic work-up.