Guidelines and good clinical practice recommendations for contrast enhanced ultrasound (CEUS) - update 2008

Contrast-enhanced ultrasound: The evolving applications

Contrast-enhanced ultrasound (CEUS) is a major breakthrough for ultrasound imaging in recent years. By using a microbubble contrast agent and contrast-specific imaging software, CEUS is able to depict the micro- and macro-circulation of the targeted organ, which in turn leads to improved performance in diagnosis. Due to the special dual blood supply system in the liver, CEUS is particularly suitable for liver imaging. It is evident that CEUS facilitates improvement for characterization of focal liver lesions (FLLs), detection of liver malignancy, guidance for interventional procedures, and evaluation of treatment response after local therapies. CEUS has been demonstrated to be equal to contrast-enhanced computed tomography or magnetic resonance imaging for the characterization of FLLs. In addition, the applicability of CEUS has expanded to non-liver structures such as gallbladder, bile duct, pancreas, kidney, spleen, breast, thyroid, and prostate. The usefulness of CEUS in these applications is confirmed by extensive literature production. Novel applications include detecting bleeding sites and hematomas in patients with abdominal trauma, guiding percutaneous injection therapy and therefore achieving the goal of using interventional ultrasonography in managing splenic trauma, assessing the activity of Crohn’s disease, and detecting suspected endoleaks after endovascular abdominal aneurysm repair. Contrast-enhanced intraoperative ultrasound (US) and intracavitary use of CEUS have been developed and clinically studied. The potential use of CEUS involves sentinel lymph node detection, drug or gene delivery, and molecular imaging. In conclusion, the advent of CEUS has greatly enhanced the usefulness of US and even changed the status of US in clinical practice. The application of CEUS in the clinic is continuously evolving and it is expected that its use will be expanded further in the future.

Detection Of Focal Liver Lesions In Cirrhotic Liver Using Contrast-Enhanced Ultrasound

Patients with liver cirrhosis are at increased risk of hepatocellular carcinoma (HCC). Conventional or baseline ultrasound (BUS) is often used as the first-line tool for HCC surveillance or detection, but the accuracy of BUS in HCC detection or differentiation from other focal liver lesions (FLLs) is limited. Contrast-enhanced ultrasound (CEUS) represents a recent revolution in the field of ultrasonography and it has become increasingly important in the detection and evaluation of FLLs. In CEUS, HCC typically exhibits arterial hyper-enhancement and portal-venous washout represented by hypo-enhanced lesions in the portal venous and late phases. The detection rate of HCC was significantly higher with CEUS compared with BUS. Even regenerative or some dysplastic nodules may exhibit arterial hyper-enhancement as they are differentiated from HCC by its iso-enhancing pattern in portal and late phases. The contrast-enhancement patterns of other different types of benign and malignant FLLs, as well as their detection rates with CEUS, were also discussed.

Contrast-enhanced ultrasound in the biliary system: Potential uses and indications

Conventional ultrasound (US) is the first-line imaging investigation for biliary diseases. However, it is lack of the ability to depict the microcirculation of some lesions which may lead to failure in diagnosis for some biliary diseases. The use of contrast-enhanced US (CEUS) has reached the field of bile duct disease in recent years and promising results have been achieved. In this review, the methodology, image interpretation, enhancement pattern, clinical usefulness, and indications for CEUS in the biliary system are summarized. CEUS may be indicated in the biliary system under the following circumstances: (1) Where there is a need to make a characterization of intrahepatic cholangiocarcinoma (ICC); (2) For differentiation diagnosis between ICC and other tumors (i.e. hepatocellular carcinoma or liver metastasis) or infectious diseases; (3) For differentiation diagnosis between biliary cystadenoma and biliary cystadenocarcinoma; (4) To detect malignant change in Caroli’s disease; (5) To depict the extent of Klatskin’s tumor with greater clarity; (6) To make a distinction between gallbladder cholesterol polyp, adenoma and polypoid cancer; (7) To make a distinction between chronic cholecystitis with thickened wall and gallbladder cancer; (8) For differentiation diagnosis between motionless sludge and gallbladder cancer; (9) For differentiation diagnosis between common bile duct cancer and sludge or stone without acoustic shadowing; and (10) In patients who are suspected of having a drop of their percutaneous transhepatic cholangiodrainage tube, US contrast agent can be administered to through the tube detect the site of the tube.

[Usefulness of contrast-enhanced ultrasonography in daily clinical practice: a multicenter study in Spain]

OBJECTIVES

We aimed to determine whether the use of ultrasonographic contrast agents improves the diagnostic performance of ultrasonography (US).

MATERIAL AND METHODS

We carried out a prospective multicenter study in 42 hospitals. We included 1786 patients with inconclusive US; 84.9% of the inconclusive studies were abdominal US (including studies of the liver, kidneys, spleen, and other sites), 6.2% were studies of the peripheral vessels, 4.3% were breast studies, and 4.6% were other studies. We evaluated the type of contrast-enhanced US (color Doppler or contrast-specific method), type of contrast agent, dose and number of doses, and type of administration (bolus or infusion). We evaluated whether the findings at contrast-enhanced US improved the diagnostic performance of unenhanced US and whether they enabled a conclusive diagnosis to be reached.

RESULTS

The contrast agent SonoVue was used in 99.9% of the studies; a single dose of contrast agent was used in 84.8%, and the contrast agent was administered in bolus in 98.5%. Contrast-enhanced US improved the diagnostic performance in 91.6% of cases and enabled the conclusive diagnosis in 69.2%. The best diagnostic performance was obtained in the supraaortic trunks, where a definitive diagnosis was reached in 95.4% of cases, followed by the abdominal area, with a conclusive diagnosis in 72.6% of cases.

CONCLUSIONS

The use of contrast-enhanced US significantly improved the diagnostic performance of US and enabled a conclusive diagnosis in most cases.

Contrast enhanced ultrasound of splenic lymphoma involvement

OBJECTIVE

The aim of this study was to compare the value of contrast-enhanced ultrasonography (CEUS) with standard B-mode ultrasound (US) for diagnosis of splenic lymphoma involvement.

METHODS

From 04/2005 to 10/2008 n=250 lymphoma patients were investigated by standard B-mode US. A homogeneous splenic echotexture was found in 199 patients (79%). To clarify the benefit of CEUS in this group a pilot series was performed with 16 of the 199 lymphoma patients. All patients with an abnormal splenic echotexture on standard B-Mode US (n=51) including focal hypoechoic splenic lesions (n=41) and an inhomogeneous splenic texture (n=10) were studied by CEUS. CEUS data were retrospectively evaluated. The diagnoses included indolent lymphoma (n=27), aggressive lymphoma (n=14), and Hodgkin's disease (n=10). Number and size of lesions were determined by B-mode US and CEUS. The visualisation of splenic lymphoma involvement by CEUS in comparison to B-mode US was classified as worse, equal, or better.

RESULTS

All patients with a homogeneous spleen on B-mode US (n=16) had no visible focal lesions on CEUS. Study patients with focal lesions (n=41) had a hypoechoic (n=22) or isoechoic (n=19) enhancement during the arterial phase, and a hypoechoic enhancement during the parenchymal phase (n=41). The visualisation of focal splenic lymphoma was equal (n=32), better (n=6), or worse (n=3). In all study patients with an inhomogeneous spleen on B-mode US (n=10) no focal lesions were found by CEUS and the value of CEUS therefore was classified as worse.

CONCLUSION

CEUS has no clear advantage for diagnosis of splenic lymphoma involvement.

Evaluation of the microcirculatory disturbance of biliary ischemia after liver transplantation with contrast-enhanced ultrasound: preliminary experience

The aim of this study was to determine the efficacy of contrast-enhanced ultrasound for depicting the perfusion of hilar bile ducts in ischemic-type biliary lesions after orthotopic liver transplantation. Thirteen transplant recipients with ischemic-type biliary lesions and 12 patients without ischemic-type biliary lesions underwent ultrasound examinations after the injection of 1.5 mL of an intravenous contrast agent. The enhancement of the hilar bile duct wall in the arterial, portal venous, and late phases was qualitatively graded as higher, equal, lower, or none with respect to that of the adjacent liver parenchyma. No or low contrast enhancement was seen in 10 of 13 patients (76.90%) with biliary ischemia, whereas increased contrast enhancement with respect to the normal liver parenchyma was found in all 12 patients without biliary ischemia. The difference in the enhancement patterns between the 2 groups was significant (P = 0.0001). In conclusion, contrast-enhanced ultrasound is a new imaging modality to depict perfusion of the hilar bile duct. No or low contrast enhancement of the bile duct wall in the arterial phase may reflect the microcirculatory disturbance of biliary ischemia and may contribute to its early diagnosis.

Contrast-enhanced endoscopic ultrasound and elastosonoendoscopy

Until recently, there was no contrast harmonic imaging technique available for EUS examination. Second-generation US contrast agents produce harmonic signals at lower acoustic powers and, therefore, are suitable for EUS imaging at low acoustic powers. CE-EUS could provide a contribution to the differential diagnosis between a primary pancreatic carcinoma, chronic pancreatitis and a pancreatic metastasis, and therefore can have a decisive influence on the selection of appropriate therapeutic strategies (follow-up, chemotherapy or surgery, for example). However, histology remains the standard in the differential diagnosis of pancreatic tumours. Regarding lymph nodes, CE-EUS cannot replace EUS-guided fine-needle aspiration. Elastography examines the elastic properties of tissues by applying a slight compression to the tissue and comparing an image obtained before and after this compression. EUS elastography is a new application in the field of endosonography and seems to be able to differentiate fibrous and benign tissue from malignant lesions. While our results are very encouraging, further research will be needed to further define the place of this new technique and should be aimed at further defining criteria for accurate elastography as well as subsequently assessing the technique using multiple operators in a blinded setting. EUS-guided sonoelastography has the potential for further guiding the diagnosis and therapy of gastrointestinal-related tumours.

Hepatocellular carcinoma with cirrhosis: are patients with neoplastic main portal vein invasion eligible for percutaneous radiofrequency ablation of both the nodule and the portal venous tumor thrombus?

OBJECTIVE

The purpose of this study was to examine the results of percutaneous radiofrequency ablation of both medium-sized hepatocellular carcinoma (HCC) and the accompanying main portal venous tumor thrombus in patients with cirrhosis.

SUBJECTS AND METHODS

From January 2005 to January 2008, among 1,837 consecutively registered patients with HCC seen at our institution, 412 had HCC and portal venous invasion; 27 of the 412 had a single HCC nodule accompanied by main portal venous tumor thrombus. Thirteen patients (10 men, three women; mean age, 70 years; range, 66-74 years) with 13 HCC nodules 3.7-5 cm in diameter extending into the main portal trunk underwent percutaneous radiofrequency ablation. Fourteen matched patients (10 men, four women; mean age, 69 years; range, 67-73 years) with 14 HCC nodules 3.6-4.8 cm in diameter extending into the main portal trunk refused radiofrequency ablation and composed the control group. Diagnosis of main portal venous tumor thrombus was made with fine-needle biopsy in all cases. Radiofrequency ablation was performed first on the main portal venous tumor thrombus and then on the HCC nodule. Efficacy of radiofrequency was defined as complete necrosis of HCC and complete recanalization of the main portal trunk and its branches. HCC necrosis was evaluated with enhanced CT. Recanalization of portal vessels was analyzed with color Doppler and contrast-enhanced ultrasound. Radiofrequency ablation was performed under ultrasound guidance with a perfused needle electrode.

RESULTS

Complete necrosis of the HCC associated with complete recanalization of the main portal vein and its branches was achieved in 10 patients (efficacy, 77%). In the other three patients, necrosis of the HCC ranged from 70% to 90%, and recanalization of the main portal trunk was not complete. No major complications occurred. In three cases, mild to moderate ascites and increased aspartate aminotransferase and alanine aminotransferase levels were found. The follow-up periods ranged from 3 to 36 months among the treated patients and 2 to 10 months among the untreated patients. The cumulative survival rate was 77% 6, 12, and 36 months after procedure in the treated group and 43% and 0% 6 and 12 months after diagnosis in the untreated group (p < 0.0001). All 10 successfully treated patients were alive and the portal system was patent at the end of the follow-up period. All three untreated patients died of progressive disease within 5 months of diagnosis.

CONCLUSION

Radiofrequency ablation can destroy both single intraparenchymal medium-sized HCCs and the accompanying main portal venous tumor thrombus with high efficacy and safety and a low rate of complications.

Differentiation of benign from malignant focal splenic lesions using sulfur hexafluoride-filled microbubble contrast-enhanced pulse-inversion sonography

OBJECTIVE

The purpose of our study was to evaluate whether sonographic characterization of focal splenic lesions could be improved by using low mechanical index pulse-inversion sonography after sulfur hexafluoride-filled microbubble injection.

MATERIALS AND METHODS

One hundred forty-seven splenic lesions (68 benign, 79 malignant) in 147 patients (81 men, 66 women; mean age, 51 years) underwent baseline gray-scale sonography and sulfur hexafluoride-enhanced low-acoustic-power pulse-inversion sonography (mechanical index < 0.1). Two site investigators assessed in consensus lesion and splenic enhancement during arterial and parenchymal phases. Four readers (readers 1 and 2, blinded; and readers 3 and 4, unblinded to clinical data) independently reviewed baseline and contrast-enhanced sonograms and provided confidence rating for diagnosis of malignancy or benignancy. Accuracy, sensitivity, specificity, positive and negative predictive values, and areas under the receiver operating characteristic curves (A(z)) were calculated by considering biopsy results or splenectomy (51 patients) or CT or MR images followed by serial sonography 6-12 months apart (96 patients) as reference standards.

RESULTS

Benign lesions appeared predominately non- or isoenhancing relative to splenic parenchyma, whereas malignant lesions appeared predominately progressively hypoenhancing. For correct diagnosis of benignancy or malignancy, review of contrast-enhanced sonography after baseline sonography yielded significantly improved diagnostic performance (overall accuracy, 51%, 43%, 70%, and 74% before vs 83%, 81%, 92%, and 91% after contrast-enhanced sonography for readers 1, 2, 3, and 4; p < 0.05; respectively) and significantly improved diagnostic confidence (A(z), 0.770, 0.678, 0.900, and 0.917 before vs 0.935, 0.917, 0.984, and 0.959 after contrast-enhanced sonography for readers 1, 2, 3, and 4; p < 0.05; respectively).

CONCLUSION

Sulfur hexafluoride-filled microbubble-enhanced sonography improves characterization of focal splenic lesions with and without the availability of clinical data.

Intrahepatic cholangiocarcinoma and hepatocellular carcinoma: differential diagnosis with contrast-enhanced ultrasound

OBJECTIVE

We assessed the usefulness of contrast-enhanced ultrasound (CEUS) in the differentiation of intrahepatic cholangiocarcinoma (ICC) and hepatocellular carcinoma (HCC).

METHODS

The CEUS enhancement patterns of 50 ICCs were retrospectively analysed and compared with 50 HCCs. Two readers independently reviewed the baseline ultrasound (BUS) and CEUS images and the diagnostic performances were evaluated by receiver operating characteristic (ROC) analysis. Time-intensity curves (TIC) were plotted for quantification analysis.

RESULTS

In the arterial phase, peripheral rim-like hyperenhancement, heterogeneous hyperenhancement, homogeneous hyperenhancement and heterogeneous hypoenhancement were found in 25, 10, 3 and 12 of the ICCs versus 2, 29, 19 and 0 of the HCCs (P < 0.001), respectively. The diagnostic performance of both readers in terms of the area under the ROC curve (0.745 vs. 0.933 for reader 1, and 0.803 vs. 0.911 for reader 2), sensitivity (28% vs. 90%, and 44% vs. 82%) and accuracy (64% vs. 90%, and 71% vs. 90%) improved significantly after CEUS (all P < 0.05). The interobserver agreement increased from kappa = 0.575 at BUS to kappa = 0.720 after CEUS. TICs demonstrated that the intensities of the peripheral and central portions of the ICCs were lower than those of HCCs (both P < 0.05).

CONCLUSION

CEUS improves the diagnostic performance significantly in the differentiation between ICC and HCC.

Imaging features of hepatic angiomyolipomas on real-time contrast-enhanced ultrasound

The aim of this study was to evaluate the imaging features of hepatic angiomyolipoma (AML) on contrast-enhanced ultrasound (CEUS). The imaging features of 12 pathologically proven hepatic AML lesions in 10 patients who had undergone baseline ultrasound (BUS) and CEUS examinations were evaluated retrospectively. The enhancement extent, pattern and dynamic change, along with the enhancement process, on CEUS were analysed. The diagnostic results of BUS and CEUS before pathological examination were also recorded. The results showed that 75% (9/12) of the AML lesions exhibited mixed echogenicity on BUS and most showed remarkable hyperechogenicity in combination with a hypoechoic or anechoic portion. Arterial flow signals were detected in 75% (9/12) of the lesions on colour Doppler imaging. On CEUS, 66.7% (n = 8) of the 12 lesions exhibited hyperenhancement in the arterial phase, slight hyperenhancement (n = 2) or isoenhancement (n = 6) in the portal phase, and slight hyperenhancement (n = 1) or isoenhancement (n = 7) in the late phase. Three (25%) lesions exhibited hyperenhancement in the arterial phase and hypoenhancement in both portal and late phases. One (8.3%) lesion exhibited hypoenhancement throughout the CEUS process. Before pathological examination with BUS, only 3 (25%) lesions were correctly diagnosed as hepatic AML. Conversely, on CEUS, correct diagnoses were made for 66.8% (8/12) of hepatic AMLs. Therefore, arterial hyperenhancement and subsequent sustained enhancement on CEUS were found in the majority of hepatic AMLs. The combination of BUS and CEUS leads to the correct diagnosis in the majority of hepatic AMLs, and is higher than the success rate achieved by BUS alone.

Contrast enhanced ultrasound should be the initial radiological investigation to characterise focal liver lesions

INTRODUCTION

Contrast enhanced ultrasound (CEUS) involves the administration of a microbubble contrast agent followed by a US scan to evaluate the liver lesion through all phases of enhancement. Although technical difficulty and operator dependence can be encountered, CEUS is thought to be superior to conventional US and CT. This study aims to determine how effective CEUS is at characterising focal liver lesions and to establish its role in the diagnostic algorithm.

METHODS

All patients who underwent a liver CEUS performed by a single consultant radiologist were identified over a 5 year period. The CEUS report, CT, MRI and/or PET report, histopathology report and case notes were reviewed.

RESULTS

127 patients were included. CEUS correctly identified 71 of 77 malignant lesions and all of the benign liver lesions. The sensitivity of CEUS for detecting and correctly characterising a malignant FLL is therefore 92% with a specificity of 100%.

CONCLUSION

Our study shows that CEUS has a high sensitivity and specificity for characterising focal liver lesions. CEUS has advantages over CT and MRI of a high degree of safety, good patient tolerance and often availability at the time of initial detection. We therefore suggest that CEUS should be used as the initial study in the characterisation of FLLs. The study should be followed, as appropriate, by CT and MRI or PET studies. Biopsy, with its risks of tumour seeding and false negative results should only be considered after review of the imaging studies and full MDT discussion.

Differential diagnosis between benign and malignant gallbladder diseases with real-time contrast-enhanced ultrasound

The value of contrast-enhanced ultrasound (CEUS) in differential diagnosis between benign and malignant gallbladder diseases was investigated. Thirty-three patients with gallbladder carcinomas and 47 with benign gallbladder diseases underwent CEUS. The lesion enhancement time, enhancement extent, pattern, dynamic change of enhancement and the intactness of gallbladder wall were evaluated. In the early phase at CEUS, hyper-, iso-, hypo-, and non-enhancement were found in 84.8% (28/33), 9.1% (3/33), 6.1% (2/33), and 0% (0/33) of gallbladder carcinomas, and 70.3% (33/47), 17.0% (8/47), 2.1% (1/47), and 10.6% (5/47) of benign diseases (p > 0.05). Hyper-enhancement or iso-enhancement in the early phase and then fading out to hypo-enhancement within 35 s after contrast agent administration was found in 90.9% (30/33) of carcinomas and 17.0% (8/47) of benign lesions (p < 0.001). Destruction of the gallbladder wall intactness was absent in benign diseases, whereas it was present in 28 (84.8%) of the 33 carcinomas (p < 0.001). Destruction of gallbladder wall intactness on CEUS yielded the highest capability in differential diagnosis, with sensitivity, specificity, and Youden's index of 84.8% (28/33), 100% (47/47), and 0.85, respectively. Conventional US made correct original diagnoses in 55 (68.8%) patients, whereas CEUS in 77 (96.3%). Thus, CEUS is useful in differential diagnosis between malignant and benign gallbladder diseases.

Hepatocellular carcinoma: current trends in worldwide epidemiology, risk factors, diagnosis and therapeutics

Hepatocellular carcinoma (HCC) is the third most common cause of cancer-related death worldwide and, owing to changes in the prevalence of the two major risk factors, hepatitis B virus and hepatitis C virus, its overall incidence remains alarmingly high in the developing world and is steadily rising across most of the developed world. Early diagnosis remains the key to effective treatment and there have been recent advances in both the diagnosis and therapy of HCC, which have made important impacts on the disease. This review outlines the epidemiological trends, risk factors, diagnostic developments and novel therapeutics for HCC, both in the developing and developed world.

Microbubbles as ultrasound triggered drug carriers

Originally developed as contrast agents for ultrasound imaging and diagnostics, in the past years, microbubbles have made their way back from the patients' bedside to the researcher's laboratory. Microbubbles are currently believed to have great potential as carriers for drugs, small molecules, nucleic acids, and proteins. This review provides insight into this intriguing new frontier from the perspective of the pharmaceutical scientist. First, basic aspects on the application of ultrasound-targeted microbubble destruction for drug delivery will be presented. Next, we will review the recently applied approaches for manufacturing and drug-loading microbubbles. Important quality issues and characterization techniques for advanced microbubble formulation will be discussed. Finally, we will provide an assessment of the prospects for microbubbles in drug and gene therapy, illustrating the problems and requirements for their future development.

Contrast-enhanced ultrasonography in nodular splenomegaly associated with type B Niemann-Pick disease: an atypical hemangioma enhancement pattern

INTRODUCTION

Niemann-Pick disease (NPD) types A and B are lipid storage disorders. NPD type A is a fatal disorder of infancy. Type B is a non-neuronopathic form observed in children and adults. It is associated with enlargement of the liver, spleen, or both, and nodular splenomegaly may be detected with ultrasound.

METHODS

A 21-year-old female was admitted to the Emergency Room with fever, pharyngitis, and left upper quadrant abdominal pain. Labwork revealed anemia, thrombocytopenia, increased levels of AST, ALT, GGT, AF, LDH, triglycerides, and total cholesterol and low levels of HDL-cholesterol. PCR blood assays for CMV and EBV were both negative. Chest X-ray was unremarkable. Transabdominal B-mode ultrasound (US) revealed splenomegaly (long axis: >22 cm), an irregular subcapsular hypoechoic lesion in the superior pole that was consistent with splenic infarction, and multiple round highly echogenic nodes measuring 1-5 cm in diameter. Contrast-enhanced ultrasonography (CEUS) was performed using SonoVue(®) (Bracco).

RESULTS

The presence of a splenic infarction was confirmed. The nodular lesions showed arterial-phase enhancement with late parenchymal phase wash-out. (18)F-FDG-PET revealed splenic nodular uptake. Primary splenic lymphoma was suspected, and the patient underwent open splenectomy. The diagnosis was type B NPD with splenic hemangiomas.

DISCUSSION

CEUS confirmed the diagnosis and extent of splenic infarction, but the nodular atypical enhancement pattern together with nodular (18)F-FDG-PET uptake was misleading, suggesting as it did lymphoproliferative involvement of the spleen.

Treatment response evaluation with three-dimensional contrast-enhanced ultrasound for liver cancer after local therapies

OBJECTIVE

To investigate the potential usefulness of three-dimensional contrast-enhanced ultrasound (3D-CEUS) in evaluating the treatment response for liver cancer after local therapies.

METHODS

A total of 107 lesions in 95 consecutive patients with liver cancer underwent local therapies and thereafter received low acoustic power 3D-CEUS examination. The LOGIQ 9 ultrasound scanner and a volume transducer were used and the ultrasound contrast agent was SonoVue. The image quality of 3D-CEUS images was evaluated and the influence of 3D-CEUS to clinical outcome was investigated.

RESULTS

The image quality of 3D-CEUS was defined as high in 102 (102/107, 95.3%) lesions and common in 5 (5/107, 4.7%) lesions. 3D-CEUS did not change the diagnosis in any patient compared with 2D-CEUS. However, 3D-CEUS changed the management in 3 (2.8%) of 107 lesions, increased confidence but made no change in diagnosis in 85 (79.5%) lesions, added some information but did not change management or diagnosis in 15 (14.0%), and made no change in 4 (3.7%), respectively, in comparison with 2D-CEUS.

CONCLUSION

3D-CEUS enhances the diagnostic confidence in the majority of the patients and even changes the management in some patients. 3D-CEUS has potential usefulness in evaluating treatment response for liver cancer after local therapies.

Enhancement pattern of hilar cholangiocarcinoma: contrast-enhanced ultrasound versus contrast-enhanced computed tomography

OBJECTIVE

To compare the enhancement pattern of hilar cholangiocarcinoma on contrast-enhanced ultrasound (CEUS) with that on contrast-enhanced computed tomography (CECT).

METHODS

Thirty-two consecutive patients with pathologically proven hilar cholangiocarcinomas were evaluated by both low mechanical index CEUS and CECT. The enhancement feature of the tumor, portal vein infiltration, and lesion conspicuity on them was investigated.

RESULTS

In the arterial phase, the numbers of the lesions showing hyperenhancement, isoenhancement, and hypoenhancement, were 14 (43.8%), 14 (43.8%), and 4 (12.6%), on CEUS, and 12 (37.5%), 9 (28.1%), and 11 (34.4%), on CECT (P=0.162). In portal phase, the numbers of the lesions showing hypoenhancement, isoenhancement, and hyperenhancement were 30 (93.8%), 1 (3.1%), and 1 (3.1%), on CEUS, and 23 (71.9%), 8 (25.0%), and 1 (3.1%), on CECT (P=0.046). The detection rates for portal vein infiltration were 84.2% (16/19) for baseline ultrasound, 89.5% (17/19) for CEUS, and 78.9% (15/19) for CECT (all P>0.05 between every two groups). CEUS significantly improved the lesion conspicuity in comparison with CECT. CEUS and CECT made correct diagnoses in 30 (93.8%) and 25 (78.1%) lesions prior to pathological examination (P=0.125).

CONCLUSION

The enhancement pattern of hilar cholangiocarcinoma on CEUS was similar with that on CECT in arterial phase, whereas in portal phase hilar cholangiocarcinoma shows hypoenhancement more likely on CEUS. CEUS and CECT lead to similar results in evaluating portal vein infiltration and diagnosis of this entity.

[Real-time contrast-enhanced ultrasound in the evaluation of focal liver lesions: diagnostic efficacy and economical issues from a French multicentric study]

The recent introduction of high-end ultrasound equipment combined with recent contrast agents provides marked improvements in the characterization of focal liver lesions as previously reported by monocentric studies. The aim of the present study was to evaluate the diagnostic performance of Contrast-Enhanced Ultrasonography (CEUS) using SonoVue as well as its medico-economic value for characterization of focal liver lesions. These nodules were not characterized on previous CT or conventional sonography. This prospective multicentric study conducted in 15 French centres found diagnostic performances similar to those reported for CT and MRI, with a concordance rate of 84.5%, sensitivity greater than 80% and specificity greater than 90% for all types of lesions. Higher acceptance was found for CEUS compared to other imaging modalities. Economical assessment based on examination reimbursment and contrast agent cost showed a lower cost for contrast ultrasound versus CT and MRI. This French multicentric study confirmed the high diagnostic value of CEUS for focal liver lesion characterization and demonstrated a lower economical impact compared to other imaging modalities such as CT and MRI.

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

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

Contrast-enhanced ultrasonography in patients with glycogen storage disease type Ia and adenomas

OBJECTIVE

The purpose of this series was to evaluate the value of contrast-enhanced ultrasonography (CEUS) in the characterization of focal liver lesions (FLLs) in patients with glycogen storage diseases (GSDs).

METHODS

Contrast-enhanced ultrasonographic data obtained for characterization of 8 FLLs (size, 0.9-10.2 cm) in 2 patients with GSD type Ia (GSD-Ia) and lesion growth or recurrent abdominal pain were reviewed and compared with computed tomographic (CT) and magnetic resonance imaging (MRI) data. After total and left hepatectomy, pathologic examination confirmed benign adenomas in 6 of the evaluated lesions. Follow-up confirmed benignity in the 2 remaining lesions.

RESULTS

In all FLLs, CEUS showed marked hypervascularity in the early arterial phase. Centripetal filling was shown in only 1 lesion, and diffuse enhancement without any clear direction was shown in all other lesions. During the portal and late phases, 6 of the 8 lesions showed sustained enhancement, including 2 lesions that appeared heterogeneous during all phases of CT and MRI. In an aspect of 1 of these 6 large adenomas, late wash-out could be explained by sinusoid compression. The other 2 adenomas showed moderate wash-out but remained homogeneous.

CONCLUSIONS

Focal liver lesions found in patients with GSD-Ia have similar patterns on CEUS compared with incidental adenomas. Global or partial hypoenhancement observed in the late phase did not indicate a transition to hepatocellular carcinoma but may have been related to ischemia.

Sonography of the small intestine

In the last two decades, there has been substantial development in the diagnostic possibilities for examining the small intestine. Compared with computerized tomography, magnetic resonance imaging, capsule endoscopy and double-balloon endoscopy, ultrasonography has the advantage of being cheap, portable, flexible and user- and patient-friendly, while at the same time providing the clinician with image data of high temporal and spatial resolution. The method has limitations with penetration in obesity and with intestinal air impairing image quality. The flexibility ultrasonography offers the examiner also implies that a systematic approach during scanning is needed. This paper reviews the basic scanning techniques and new modalities such as contrast-enhanced ultrasound, elastography, strain rate imaging, hydrosonography, allergosonography, endoscopic sonography and nutritional imaging, and the literature on disease-specific findings in the small intestine. Some of these methods have shown clinical benefit, while others are under research and development to establish their role in the diagnostic repertoire. However, along with improved overall image quality of new ultrasound scanners, these methods have enabled more anatomical and physiological changes in the small intestine to be observed. Accordingly, ultrasound of the small intestine is an attractive clinical tool to study patients with a range of diseases.

Diagnosis of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the commonest cancers worldwide, particularly in parts of the developing world, and is increasing in incidence. This article reviews the current modalities employed for the diagnosis of HCC, including serum markers, radiological techniques and histological evaluation, and summarises international guidelines for the diagnostic approach to HCC.

Microbubbles traversing the blood-brain barrier for imaging and therapy

In the last several years great progress has been made in the field of ultrasound perfusion imaging of the brain. Different approaches have been assessed and shown to be capable of early detection of cerebral perfusion deficits. Real-time low mechanical index imaging simplifies the acquisition of perfusion parameters and alleviates many of the previous imaging problems related to shadowing, uniplanar analysis, and temporal resolution. With the advent of this new, highly sensitive contrast-specific imaging technique new possibilities of real-time visualization of brain infarctions and cerebral hemorrhages have emerged. Microbubbles that traverse the blood-brain barrier (BBB) can also elicit bioeffects that may be used to open the BBB for targeted delivery of macromolecular agents to the brain. Possible ways in which substances cross the BBB after application of this novel approach include transcytosis, passage through endothelial cell cytoplasmic openings, opening of tight junctions, and free passage through injured endothelium. Although relatively little tissue damage occurs at low acoustic intensities capable of opening the BBB, no investigation has demonstrated a total lack of BBB injury when using ultrasound and microbubbles. Further studies are necessary to address the effects of ultrasound and microbubbles upon the various transport mechanisms of the BBB. Moreover, investigations aimed at elucidating how ultrasound and microbubbles interact at the molecular level of the BBB are necessary. Results of such studies will increase our understanding of the mechanisms of BBB opening and also allow a better appraisal of the safety of this technique for future clinical applications.

Imaging detection of new HCCs in cirrhotic patients treated with different techniques: Comparison of conventional US, spiral CT, and 3-dimensional contrast-enhanced US with the Navigator technique (Nav 3D CEUS)()

INTRODUCTION

The commercially available Navigator system(©) (Esaote, Italy) allows easy 3D reconstruction of a single 2D acquisition of contrast-enhanced US (CEUS) imaging of the whole liver (with volumetric correction provided by the electromagnetic device of the Navigator(©)). The aim of our study was to compare the efficacy of this panoramic technique (Nav 3D CEUS) with that of conventional US and spiral CT in the detection of new hepatic lesions in patients treated for hepatocellular carcinoma (HCC).

MATERIALS AND METHODS

From November 2006 to May 2007, we performed conventional US, Nav 3D CEUS, and spiral CT on 72 cirrhotic patients previously treated for 1 or more HCCs (M/F: 38/34; all HCV-positive; Child: A/B 58/14) (1 examination: 48 patients; 2 examinations: 20 patients; 3 examinations: 4 patients). Nav 3D CEUS was performed with SonoVue(©) (Bracco, Milan, Italy) as a contrast agent and Technos MPX(©) scanner (Esaote, Genoa, Italy). Sensitivity, specificity, diagnostic accuracy, and positive and negative predictive values (PPV and NPV, respectively) were evaluated. Differences between the techniques were assessed with the chi-square test (SPSS release-15).

RESULTS

Definitive diagnoses (based on spiral CT and additional follow-up) were: 6 cases of local recurrence (LocRecs) in 4 patients, 49 new nodules >2 cm from a treated nodule (NewNods) in 34 patients, and 10 cases of multinodular recurrence consisting of 4 or more nodules (NewMulti). The remaining 24 patients (22 treated for 1-3 nodules, 2 treated for >3 nodules) remained recurrence-free. Conventional US correctly detected 29/49 NewNods, 9/10 NewMultis, and 3/6 LocRecs (sensitivity: 59.2%; specificity: 100%; diagnostic accuracy: 73.6%; PPV: 100%; NPV: 70.1%). Spiral CT detected 42/49 NewNods plus 1 that was a false positive, 9/10 NewMultis, and all 6 LocRecs (sensitivity: 85.7%; specificity: 95.7%; diagnostic accuracy: 90.9%; PPV: 97.7%; NPV: 75.9%). 3D NAV results were: 46N (+9 multinodularN and 6 LR), 3 false-negatives, and one false-positive (sensitivity: 93.9; specificity: 97.9%; diagnostic accuracy: 95.6; PPV: 97.9; NPV: 93.9).

CONCLUSIONS

3D Nav CEUS is significantly better than US and very similar to spiral CT for detection of new HCCs. This technique revealed the presence of lesions that could not be visualized with spiral CT.

Optical microscopic findings of the behavior of perflubutane microbubbles outside and inside Kupffer cells during diagnostic ultrasound examination

PURPOSE

To investigate the behavior of perflubutane microbubbles outside and inside Kupffer cells during diagnostic ultrasound (US) examination, and to determine the thresholds of the acoustic pressure of different kinds of behavior.

METHODS

Acoustic behavior of perflubutane microbubbles inside and outside Kupffer cells in an acoustic field induced by a clinical US transducer and equipment was optically observed in vitro. The acoustic pressure was measured simultaneously by a calibrated hydrophone and an oscilloscope.

RESULTS

The acoustic behavior of microbubbles was optically categorized as stabilization, oscillation, transposition, shrinkage, and destruction. The mechanical index (MI) displayed on the US equipment correlated well with the acoustic pressure at the level of microbubbles measured hydrophonically. At a frame rate of 15 Hz with a frequency of 3.5 MHz and pulse repetition frequency of 3 KHz, the thresholds in term of MI for free microbubbles to begin oscillation, reach best oscillation, transposition, shrinkage, and destruction were 0.21, 0.44, 0.53, 0.75, and 1.03, respectively. Although adherent and phagocytosed microbubbles showed more stability enduring insonation compared with free microbubbles, the thresholds of shrinkage and destruction were MI 1.03 and 1.18 for adherent microbubbles, and 1.18 and 1.37 for phagocytosed microbubbles, respectively. Neither oscillation nor transposition of microbubbles inside Kupffer cells was observed microscopically. No cell damage because of microbubbles destruction was found in the present study.

CONCLUSION

Perflubutane microbubbles outside and inside Kupffer cells respond to external US insonation with same parameters of a clinical contrast-enhanced US study according to the acoustic pressure. Free microbubbles behave as stabilization, oscillation, transposition, shrinkage, and destruction under insonation. The adherent and phagocytosed microbubbles are more stable under insonation than free microbubbles, but still respond showing shrinkage and destruction when MI is over 1.03.

Diagnostic performance of contrast-enhanced ultrasound for complex cystic focal liver lesions: blinded reader study

The study was aimed at evaluating the diagnostic performance of contrast-enhanced ultrasound (CEUS) in characterizing complex cystic focal liver lesions (FLLs). Sixty-seven complex cystic FLLs in 65 patients were examined with conventional ultrasound (US) and real-time CEUS. The US and CEUS images were reviewed by a resident radiologist and a staff radiologist independently. Receiver operating characteristic (ROC) analysis was performed to evaluate the diagnostic performance, and the interobserver agreement was analysed. The results showed that complete non-enhancement throughout three phases of CEUS or sustained enhancement in the portal and late phases were exhibited in most benign lesions. Conversely, hypo-enhancement in the late phase was seen in all malignancies. After ROC analysis, the areas (Az) under the ROC curve were 0.774 at US versus 0.922 at CEUS (P=0.047) by the resident radiologist, and 0.917 versus 0.935 (P=0.38) by the staff radiologist. A significant difference in Az between the resident and the staff radiologists was found for US (0.774 versus 0.917, P=0.044), whereas not found for CEUS (0.922 versus 0.935, P=0.42). Interobserver agreement was improved after CEUS (kappa=0.325 at US versus kappa=0.774 at CEUS). Real-time CEUS improves the capability of discrimination between benign and malignant complex cystic FLLs, especially for the resident radiologist.

Does the echogenicity of focal liver lesions on baseline gray-scale ultrasound interfere with the diagnostic performance of contrast-enhanced ultrasound?

The objective was to evaluate whether the echogenicity of focal liver lesions (FLLs) on baseline gray-scale ultrasound (US) interferes with the diagnostic performance of contrast-enhanced US (CEUS) for small FLLs. Three-hundred and eighty-eight patients were examined by real-time CEUS using a sulfur hexafluoride-filled microbubble contrast agent. The images of 114 hyperechoic lesions, 30 isoechoic lesions and 244 hypoechoic lesions were reviewed by two blinded independent readers. A five-point confidence level was used to discriminate malignant from benign lesions, and specific diagnoses were made. The diagnostic performances were evaluated by receiver-operating characteristic (ROC) analysis. The diagnostic performances of CEUS on hyperechoic lesions in terms of the areas (Az) under the ROC curve were 0.987 (reader 1) and 0.981 (reader 2), and were 0.987 (reader 1) and 0.984 (reader 2) for iso- and hypoechoic lesions, respectively. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 87.0-95.9%, 93.1-100%, 88.6-100%, 70.0-97.1% and 90.0-95.1%, respectively. The echogenicity of FLLs on baseline gray-scale US does not appear to interfere with the diagnostic ability of CEUS for small FLLs.

A benign tumour of the liver mimicking malignant liver disease--cholangiocellular adenoma

OBJECTIVE

To describe three patients with liver lesions mimicking malignant tumours diagnosed finally, using contrast-enhanced ultrasound, as cholangiocellular adenoma (bile duct adenoma).

MATERIAL AND METHODS

Focal liver lesions found incidentally in three patients. Contrast-enhanced ultrasound was with use of Siemens or Esaote equipment, low MI technique, after an intravenous bolus of 2.4 ml Sonovue (Bracco, Italy).

RESULTS

Lesions were 9 mm, 15 mm and 20 mm in diameter and all were enhanced in the arterial phase and hypo-enhanced in the portal venous and late phases, suggesting their malignant nature. In two patients, no primary liver tumour was found, and in the third patient, previously resected for breast cancer, a tissue specimen was considered useful for characterizing tumour receptors for more targeted chemotherapy, the lesion being assumed metastatic in nature. Transcutaneous core biopsies were performed in all three patients. Pathological analysis (including the reference pathology) revealed cholangiocellular adenoma in all of them.

CONCLUSION

Cholangiocellular adenoma is a rare entity and can be a reason for possible false malignant diagnosis using contrast-enhanced ultrasound. Follow-up examinations are recommended.

The added diagnostic value of 64-row multidetector CT combined with contrast-enhanced US in the evaluation of hepatocellular nodule vascularity: implications in the diagnosis of malignancy in patients with liver cirrhosis

The aim of this study was to assess the added diagnostic value of contrast-enhanced US (CEUS) combined with 64-row multidetector CT (CT) in the assessment of hepatocellular nodule vascularity in patients with liver cirrhosis. One hundred and six cirrhotic patients (68 male, 38 female; mean age +/- SD, 70 +/- 7 years) with 121 biopsy-proven hepatocellular nodules (72 hepatocellular carcinomas, 10 dysplastic and 15 regenerative nodules, 12 hemangiomas, and 12 other benignancies) detected during US surveillance were prospectively recruited. Each nodule was scanned by CEUS during the arterial (10-40 s), portal venous (45-90 s), and delayed sinusoidal phase (from 100 s after microbubble injection to microbubble disappearance). Nodule vascularity at CEUS, CT, and combined CEUS/CT was evaluated side-by-side by two independent blinded readers who classified nodules as benign or malignant according to reference diagnostic criteria. The combined assessment of CEUS/CT provided higher sensitivity (97%, both readers) than did separate assessment of CEUS (88% reader 1; 87% reader 2) and CT (74% reader 1; 71% reader 2; P < 0.05), while no change in specificity was provided by combined analysis. The combined assessment of hepatocellular nodule vascularity at CT and CEUS improved sensitivity in the diagnosis of malignancy in patients with liver cirrhosis.