Characterization of benign hepatic tumors arising in fatty liver with SonoVue and pulse inversion US

CEUS LI-RADS: a pictorial review

Contrast-enhanced ultrasound (CEUS) greatly improved the diagnostic accuracy of US in the detection and characterization of focal liver lesions (FLLs), and it is suggested and often included in many international guidelines as an important diagnostic tool in the imaging work-up of cirrhotic patients at risk for developing hepatocellular carcinoma (HCC). In particular, CEUS Liver Imaging Reporting and Data System (LI-RADS) provides standardized terminology, interpretation, and reporting for the diagnosis of HCC. The aim of this pictorial essay is to illustrate CEUS features of nodules discovered at US in cirrhotic liver according to LI-RADS categorization.

Multiple liver pseudotumors due to hepatic steatosis and fatty sparing: A non-invasive imaging approach

Hepatic steatosis is a frequent benign liver condition that can be idiopathic or secondary. The degree of fatty liver infiltration can be focal, diffuse or patchy. In this study, we present two patients with hepatic steatosis and multiple nodular liver lesions, due to fatty infiltration and fatty sparing respectively, mimicking a primary tumor or metastases (“pseudotumors”).

Since the differential diagnosis of this kind of lesions can be difficult based on imaging alone, the knowledge of Contrast-Enhanced Ultrasound (CEUS) and Magnetic Resonance Imaging (MRI) findings may help radiologists to avoid an incorrect diagnosis of liver tumor, and unnecessary biopsies.

Detection of liver metastases in cancer patients with geographic fatty infiltration of the liver: the added value of contrast-enhanced sonography

Purpose

The aim of this study is to assess the role of contrast-enhanced ultrasonography (CEUS) in the detection of liver metastases in cancer patients with geographic liver fatty deposition on greyscale ultrasonography (US).

Methods

Thirty-seven consecutive cancer patients (24 women and 13 men; age, 33 to 80 years; mean, 58.1 years) with geographic liver fatty deposition, but without any detectable focal liver lesion on greyscale US, underwent sulphur hexafluoride-enhanced US. Two readers reported by consensus the presence, size, and location of any detected lesion. All patients underwent magnetic resonance imaging (MRI) as a confirmatory study. Sensitivity, specificity, positive and negative predictive values (PPV and NPV), and accuracy were calculated.

Results

Seven focal liver lesions (size, 4 to 10 mm; mean, 6.1 mm) were detected in 4/37 patients (10.8%): four metastases (size, 5 to 10 mm; mean, 6.7 mm) were detected both by CEUS and MRI, with one hemangioma and two cysts (size range, 4 to 6 mm; mean, 5.3 mm) detected by MRI only. In 1/37 patients (2.7%), CEUS misdiagnosed geographic fatty change as three metastases. In 32/37 patients (86.5%), no lesions were detected. Sensitivity, specificity, PPV, NPV, and accuracy of CEUS were 100% (95% confidence Interval [CI], 1.000 to 1.000), 97.1% (95% CI, 0.914 to 1.027), 75%, 100%, and 97.3%, respectively. No statistically significant differences were found between CEUS and MRI in the detection of focal liver lesions (P=0.480), whereas both of them performed better than baseline US (P<0.001).

Conclusion

CEUS improves the detection of liver metastases in cancer patients with geographic liver fatty deposition on greyscale US.

Percutaneous microwave ablation for benign focal liver lesions: Initial clinical results

Benign focal liver lesions (BFLLs) have become a common disease diagnosed in the clinical setting following the advancement of imaging techniques. The aim of the present study was to evaluate the safety and clinical outcomes of percutaneous microwave (MW) ablation, guided by ultrasound (US), for the treatment of BFLLs. Between May 2005 and January 2011, 44 BFLLs (mean maximum diameter, 33.9±13.1 mm) in 37 patients (23 women and 14 men) were treated by US-guided percutaneous MW ablation with cooled-shaft antennae. The pathological diagnosis of a BFLL was confirmed in 91.9% (34/37) of patients using a US-guided core needle biopsy prior to ablation. The BFLLs in the other 3 cases were diagnosed by typical presentations on contrast-enhanced imaging, as the patients refused to undergo biopsies. Five inclusion criteria, including indeterminate diagnoses of nodules on contrast-enhanced imaging prior to pathological verification, were recommended. The median follow-up period was 27.0 months (range, 6-73 months). The mean MW ablation energy and time were 55.0±41.6 kJ (range, 13.5-207 kJ) and 1,039.9±706.2 sec (range, 270-3,450 sec) per lesion, respectively. In total, 40 nodules (90.9%) were completely ablated, and no evidence of recurrence was demonstrated on contrast-enhanced imaging follow-up. The other 4 nodules (9.1%) were partially ablated due to the proximity of adjacent vital organs. Minor complications without sequelae included local pain and transient hemoglobinuria and no major complications occurred in peri-ablation. Overall, US-guided percutaneous MW ablation is a safe, effective and minimally invasive therapy for BFLLs in selected patients who are non-surgical candidates.

Comparison of contrast-enhanced ultrasonography with grey-scale ultrasonography and contrast-enhanced computed tomography in diagnosing focal fatty liver infiltrations and focal fatty sparing

PURPOSE

Fatty liver infiltrations and fatty sparing impair diagnostic performance of grey-scale ultrasonography in differentiating malignant and benign focal liver lesions. In the study, we present our experience in diagnosing focal fatty liver infiltrations and focal fatty sparing with contrastenhanced ultrasonography (CEUS) in comparison to grey-scale ultrasonography and contrast-enhanced computed tomography (CECT).

MATERIAL AND METHOD

The retrospective study group (n=82 patients), included 44 (53.7%) men, 38 (46.3%) women (aged 29- 81 years, mean 55.8 years) with 48 focal fatty liver infiltrations and 34 focal fatty sparing. All patients underwent grey-scale ultrasonography (US), CEUS using SonoVue® and CECT executed within the 7 days.

RESULTS

With US, CEUS and CECT focal fatty liver infiltrations were diagnosed in 22, 46 and 44 cases, respectively. The following values were obtained: sensitivity - 45.8%, 95.8% and 91.7%, specificity - 100% for all, accuracy - 95.2%, 99.6% and 99.3%, respectively. Focal fatty sparing was diagnosed in 16, 31 and 30 cases, respectively. The following values were obtained: sensitivity - 47.1%, 91.2% and 88.2%, specificity - 99.8%, 100% and 100%, accuracy - 95.6%, 99.4% and 99.3%, respectively. No statistically significant differences were found in sensitivity of diagnosing focal fatty liver infiltrations and focal fatty liver sparing between CEUS and CECT. Sensitivity of grey-scale ultrasonography was significantly lower when compared to those of CEUS and CECT (p<0.001).

CONCLUSION

CEUS is as sensitive as CECT in focal fatty infiltrations and focal fatty sparing diagnosing. However, CEUS provides more information than CECT about the vasculature and enhancement pattern of focal fatty liver infiltrations.

The effect of contrast medium SonoVue® on the electric charge density of blood cells

The effect of contrast medium SonoVue® on the electric charge density of blood cells (erythrocytes and thrombocytes) was measured using a microelectrophoretic method. We examined the effect of adsorbed H⁺ and OH⁻ ions on the surface charge of erythrocytes or thrombocytes. Surface charge density values were determined from electrophoretic mobility measurements of blood cells performed at various pH levels. The interaction between solution ions and the erythrocyte's or thrombocyte's surface was described by a four-component equilibrium model. The agreement between the experimental and theoretical charge variation curves of the erythrocytes and thrombocytes was good at pH 2-9. The deviation observed at a higher pH may be caused by disregarding interactions between the functional groups of blood cells.

Source and clinical motivation of orders for contrast-enhanced sonography (CEUS) of the liver: A prospective single-center survey

Contrast-enhanced sonography (CEUS) has become a routine part of diagnostic imaging of the liver. Its possibilities, limitations, and indications have been defined in adequately large clinical series and in guidelines and recommendations. We prospectively evaluated physicians' orders for hepatic CEUS received in the radiology department of a large oncology center in Naples, Italy from May 2009 to April 2010. Radiologists performing the CEUS examinations filled out a form that included patient demography, source and type of patient referral, and clinical indications for the examination. During the study period, 564 patients aged 17-86 years (mean, 58 years) were referred to our department for CEUS liver studies (total: 644; 491 outpatient studies, 153 inpatient studies). This included 4 examinations that were ordered by the patient's physician but not performed by our staff. The majority of the CEUS examinations (n = 583; 90.5%) were regularly scheduled procedures ordered by clinical specialists from our center (77.3%) or other centers (11.8%); by general practitioners (on their own initiative) (0.8%); or by other figures (0.6%). The remaining 61 examinations (9.5%) were unscheduled procedures done on the initiative of a radiologist following conventional sonography (US). Fewer than half (47.8%) of the examinations were requested as first-line assessments. The others were ordered to clarify inconclusive findings generated by conventional US (30%) or by a more sophisticated imaging study (CT, MRI, PET) (16.1%) or to resolve discrepancies between CT, MRI, and/or PET findings (6%). CEUS is a relatively noninvasive, low-cost imaging study that is simple to perform and requires no particular patient preparation. This may explain its increasing use to clarify doubts raised by conventional US and other more sophisticated imaging studies.

C-11 acetate does not enhance usefulness of F-18 FDG PET/CT in differentiating between focal nodular hyperplasia and hepatic adenoma

PURPOSE OF THE REPORT

We assessed the usefulness of F-18 fluorodeoxyglucose positron emission tomography (FDG PET) and C-11 acetate PET (AC PET) in distinguishing hepatic lesions due to consequential disease (hepatocellular adenoma and malignant lesions) from focal nodular hyperplasia (FNH) in patients at low risk of malignancy.

MATERIALS AND METHODS

Thirty-one patients with 43 lesions were prospectively enrolled. The diagnostic work-up included Doppler and contrast-enhanced ultrasonography, contrast-enhanced computed tomography, and/or magnetic resonance imaging. Fine needle biopsy was performed if the imaging study was inconclusive. The work-up revealed 36 FNH and 7 consequential lesions (5 hepatocellular adenoma, 1 hepatoma, and 1 metastasis). All patients underwent FDG and AC PET. FDG PET with target/background ratio (T/Br) greater than 1.2 and AC PET with T/Br of less than 1.2 were considered positive test for consequential disease.

RESULTS

On FDG PET, we had 6 true-positive out of 7 lesions due to consequential diseases, with a sensitivity of 85.7%, and 33 true-negative out of 36 lesions with FNH, with a specificity of 91.7%. Using AC PET, there were 2 true-positive lesions out of 7 caused by neoplasms, with a sensitivity of 28.6%, and 34 true-negative lesions out of 36 FNH, with a specificity of 94.4%.

CONCLUSIONS

When the goal is differentiating FNH from liver neoplasms, AC PET offered no additional diagnostic advantage over what is achieved with FDG PET.

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.

Contrast-enhanced ultrasound with SonoVue: differentiation between benign and malignant focal liver lesions in 317 patients

PURPOSE

The aim of the study was to investigate the ability of contrast-enhanced sonography (CEUS) with the contrast agent SonoVue to differentiate between benign and malignant focal liver lesions.

METHODS

In a prospective study, we examined 317 patients (204 males, 113 females, aged 59 +/- 12 years) with focal liver lesions detected by B-mode gray-scale sonography. After intravenous injection of 1.2 mL SonoVue, the liver was examined continuously for 3 minutes using low-MI sonography with contrast-specific software. Final diagnosis was established by histopathology, CT, MRI, or HIDA-scintigraphy.

RESULTS

Two hundred nine patients had malignant focal lesions, including 107 hepatocellular carcinomas, 70 metastases, 26 cholangiocellular carcinomas, and 6 other types of malignancy. One hundred eight patients had benign focal lesions, including 30 regenerative nodules, 30 hemangiomas, 13 cases of focal nodular hyperplasia, 12 abscesses, 8 cases of necrosis, 7 cases of focal steatosis areas, and 8 other benign lesions. Hypoenhancement or no enhancement in the late phase was found in 91% of the malignant lesions but in only 37% of the benign lesions (p < 0.001, sensitivity = 64%, specificity = 93%). Hyperenhancement in the late phase was found in 20% of the benign lesions but in none of the malignant lesions (p < 0.001, sensitivity = 21%, specificity = 100%). Hyperenhancement in the early phase with diffuse complete enhancement was found in 30% of the patients with malignant lesions but in only 2% of the patients with benign lesions (p < 0.001, sensitivity = 30%, specificity = 98%). CEUS had a sensitivity of 90%, a specificity of 99%, and an accuracy of 89% in the diagnosis of malignant liver lesions.

CONCLUSION

CEUS is helpful in the differentiation between benign and malignant focal liver lesions.

Focal hypoechoic tumors of Fatty liver: characterization of conventional and contrast-enhanced ultrasonography

OBJECTIVE

The purpose of this study was to investigate the characteristics of focal hypoechoic tumors of fatty liver using conventional ultrasonography and contrast-enhanced ultrasonography (CEUS).

METHODS

Sixty-four hypoechoic tumors of fatty liver in 52 patients were examined by both conventional ultrasonography and CEUS. Contrast pulse sequencing and a sulfur hexafluoride contrast agent were used for CEUS. The enhancement patterns were evaluated in real time. Results. Hypoechoic tumors of fatty liver showed posterior echo enhancement, including 71.4% (25 of 35) of hemangiomas, 73.3% (11 of 15) of metastases, and 50.0% (3 of 6) of hepatocellular carcinomas (HCCs) on conventional ultrasonography. During the early arterial phase, 62.5% (5 of 8) of focal nodular hyperplasia lesions showed a central spoked wheel enhancement pattern, whereas the remaining 37.5% (3 of 8) showed eccentric spoked wheel enhancement. During the arterial phase, 97.1% (34 of 35) of hemangiomas showed peripheral enhancement and centripetal fill-in, including ringlike peripheral enhancement (12 of 35), small nodular peripheral enhancement (19 of 35), and massive irregular peripheral enhancement (3 of 35). In total, 76.5% (26 of 34) of hemangiomas were completely filled in. All HCCs showed complete enhancement from 9 to 24 seconds during the arterial phase and began to wash out from 21 to 114 seconds. During the arterial phase, 40.0% (6 of 15) of metastases showed ringlike enhancement; 26.7% (4 of 15) showed slight hyperenhancement; 13.3% (2 of 15) showed hyperenhancement quickly; and the remaining 20.0% (3 of 15) showed heterogeneous hyperenhancement. All metastatic tumors began to wash out from 25 to 40 seconds. In total, 92.2% (59 of 64) of focal hypoechoic tumors of fatty liver were diagnosed as the correct pathologic type with CEUS.

CONCLUSIONS

With CEUS, characterization of hypoechoic tumors of fatty liver is greatly improved.

Benign hepatic tumors and iatrogenic pseudotumors

Myriad benign tumors may be found in the liver; they can be classified according to their cell of origin into tumors of hepatocellular, cholangiocellular, or mesenchymal origin. Common benign hepatic tumors may pose a diagnostic dilemma when they manifest with atypical imaging features. Less frequently encountered benign hepatic tumors such as inflammatory pseudotumor or biliary cystadenoma demonstrate less specific imaging features; however, awareness of their findings is useful in narrowing differential diagnostic considerations. In addition, certain iatrogenically induced abnormalities of the liver may be confused with more ominous findings such as infection or neoplasia. However, knowledge of their common imaging appearances, in addition to the clinical history, is critical in correctly diagnosing and characterizing iatrogenic abnormalities of the liver. Familiarity with both expected and unexpected imaging appearances of common benign hepatic tumors, less commonly encountered benign hepatic tumors, and iatrogenic abnormalities potentially masquerading as hepatic tumors allows the radiologist to achieve an informed differential diagnosis.

Hepatocellular cancer response to radiofrequency tumor ablation: contrast-enhanced ultrasound

Radiofrequency ablation (RFA) is increasingly being used as percutaneous treatment of choice for patients with early stage hepatocellular carcinoma (HCC). An accurate assessment of the RFA therapeutic response is of crucial importance, considering that a complete tumor ablation significantly increases patient survival, whereas residual unablated tumor calls for additional treatment. Imaging modalities play a pivotal role in accomplishing this task, but ultrasound (US) is not considered a reliable modality for the evaluation of the real extent of necrosis, even when color/power Doppler techniques are used. Recently, newer microbubble-based US contrast agents used in combination with grey-scale US techniques, which are very sensitive to non-linear behavior of microbubbles, have been introduced. These features have opened new prospects in liver ultrasound and may have a great impact on daily practice, including cost-effective assessment of therapeutic response of percutaneous ablative therapies. Technical evolution of CEUS focusing on findings after RFA are illustrated. These latter are detailed, cross-referenced with the literature and discussed on the basis of our personal experience. Timing of CEUS posttreatment assessment among with advantages and limitations of CEUS are also described with a perspective on further technologic refinement.