Liver ultrasound elastography: More than staging the disease

Ultrasound elastography is perhaps the most important breakthrough in the evolution of ultrasonography in the last 15 years. Since transient elastography was introduced, many other methods have been developed and became more and more widely available. The value of ultrasound elastography in staging a chronic liver disease has been established by numerous studies. There have been many studies that have shown that using liver elastography it is possible to predict thepresence of the complications of cirrhosis: portal hypertension, presence of esophageal varices(and even their risk of bleeding) and hepatocellular carcinoma. It has been shown that liver elastography can predict the progression of liver fibrosis and also the survival(hepatic events- free) of the patients with chronic liver diseases. These are the real quests of the clinicians, this is the ultimate scope of any medical investigation-to predict the outcome of a patient and to help making therapeutic decisions. I brought together only a small amount of the data that has already been written on this subject to support my affirmation that liver ultrasound elastography is more than a tool for staging the liver disease, but it is also comparable to a crystal ball which in the hands of a skilled clinician can reveal the future of the patient and can help to improve this future.

Ultrasound Biometry of the Liver at the Point “G” University Hospital Center in Bamako

Introduction: Biometrics therefore corresponds to the measurement of the morphological elements of humans. One of the most common ultrasound requests by clinicians is the assessment of liver size. The aim of our study was to study liver biometry using ultrasound in healthy adult subjects. Material and Methods: This was a prospective, descriptive and analytical study, carried out at CHU Point-G over a period of 7 months. A liver ultrasound was performed on 100 individuals without lesions, by a doctor in his final year of specialization in radiology and medical imaging. For each subject, we determined the height and anteroposterior diameter of the right liver and the left liver. Results: The mean age was 39.05 ± 16.86 years. The body mass index (BMI) 18.5 - 24.9 group was the most represented with 58%. The mean height of the right liver was 138.40 ± 14.85 mm. It was 136.81 ± 14.70 mm in men and 139.92 ± 14.99 mm in women (P = 0.306). That of the left liver was 95.55 ± 14.34 mm, in men, it was 91.79 ± 13.51 mm and 99.16 ± 14.31 mm in women (P = 0.019). We found a significant correlation between right liver height and BMI (P = 0.013). Conclusion: The mean values of liver biometry were established in our series. There was a significant correlation between right liver height and BMI. Liver ultrasound remains a reliable technique for liver biometry.

Contrast-enhanced ultrasound Liver Imaging Reporting and Data System:Lights and shadows in hepatocellular carcinoma and cholangiocellular carcinoma diagnosis

BACKGROUND Contrast-enhanced ultrasound(CEUS)is considered a secondary examination compared to computed tomography(CT)and magnetic resonance imaging(MRI)in the diagnosis of hepatocellular carcinoma(HCC),due to the risk of misdiagnosing intrahepatic cholangiocarcinoma(ICC).The introduction of CEUS Liver Imaging Reporting and Data System(CEUS LI-RADS)might overcome this limitation.Even though data from the literature seems promising,its reliability in real-life context has not been well-established yet.AIM To test the accuracy of CEUS LI-RADS for correctly diagnosing HCC and ICC in cirrhosis.METHODS CEUS LI-RADS class was retrospectively assigned to 511 nodules identified in 269 patients suffering from liver cirrhosis.The diagnostic standard for all nodules was either biopsy(102 nodules)or CT/MRI(409 nodules).Common diagnostic accuracy indexes such as sensitivity,specificity,positive predictive value(PPV),and negative predictive value(NPV)were assessed for the following associations:CEUS LR-5 and HCC;CEUS LR-4 and 5 merged class and HCC;CEUS LR-M and ICC;and CEUS LR-3 and malignancy.The frequency of malignant lesions in CEUS LR-3 subgroups with different CEUS patterns was also determined.Inter-rater agreement for CEUS LI-RADS class assignment and for major CEUS pattern identification was evaluated.RESULTS CEUS LR-5 predicted HCC with a 67.6%sensitivity,97.7%specificity,and 99.3%PPV(P<0.001).The merging of LR-4 and 5 offered an improved 93.9%sensitivity in HCC diagnosis with a 94.3%specificity and 98.8%PPV(P<0.001).CEUS LR-M predicted ICC with a 91.3%sensitivity,96.7%specificity,and 99.6%NPV(P<0.001).CEUS LR-3 predominantly included benign lesions(only 28.8%of malignancies).In this class,the hypo-hypo pattern showed a much higher rate of malignant lesions(73.3%)than the iso-iso pattern(2.6%).Inter-rater agreement between internal raters for CEUS-LR class assignment was almost perfect(n=511,k=0.94,P<0.001),while the agreement among raters from separate centres was substantial(n=50,k=0.67,P<0.001).Agreement was stronger for arterial phase hyperenhancement(internal k=0.86,P<2.7×10-214;external k=0.8,P<0.001)than washout(internal k=0.79,P<1.6×10-202;external k=0.71,P<0.001).CONCLUSION CEUS LI-RADS is effective but can be improved by merging LR-4 and 5 to diagnose HCC and by splitting LR-3 into two subgroups to differentiate iso-iso nodules from other patterns.

Ultrasound hepatic/renal ratio and hepatic attenuation rate for quantifying liver fat content

AIM: To establish and validate a simple quantitative assessment method for nonalcoholic fatty liver disease (NAFLD) based on a combination of the ultrasound hepatic/renal ratio and hepatic attenuation rate. METHODS: A total of 170 subjects were enrolled in this study. All subjects were examined by ultrasound and H-1-magnetic resonance spectroscopy (H-1-MRS) on the same day. The ultrasound hepatic/renal echo-intensity ratio and ultrasound hepatic echo-intensity attenuation rate were obtained from ordinary ultrasound images using the MATLAB program. RESULTS: Correlation analysis revealed that the ultrasound hepatic/renal ratio and hepatic echo-intensity attenuation rate were significantly correlated with H-1-MRS liver fat content (ultrasound hepatic/renal ratio: r = 0.952, P = 0.000; hepatic echo-intensity attenuation r = 0.850, P = 0.000). The equation for predicting liver fat content by ultrasound (quantitative ultrasound model) is: liver fat content (%) = 61.519 x ultrasound hepatic/renal ratio + 167.701 x hepatic echo-intensity attenuation rate -26.736. Spearman correlation analysis revealed that the liver fat content ratio of the quantitative ultrasound model was positively correlated with serum alanine aminotransferase, aspartate aminotransferase, and triglyceride, but negatively correlated with high density lipoprotein cholesterol. Receiver operating characteristic curve analysis revealed that the optimal point for diagnosing fatty liver was 9.15% in the quantitative ultrasound model. Furthermore, in the quantitative ultrasound model, fatty liver diagnostic sensitivity and specificity were 94.7% and 100.0%, respectively, showing that the quantitative ultrasound model was better than conventional ultrasound methods or the combined ultrasound hepatic/renal ratio and hepatic echo-intensity attenuation rate. If the 1H-MRS liver fat content had a value < 15%, the sensitivity and specificity of the ultrasound quantitative model would be 81.4% and 100%, which still shows that using the model is better than the other methods. CONCLUSION: The quantitative ultrasound model is a simple, low-cost, and sensitive tool that can accurately assess hepatic fat content in clinical practice. It provides an easy and effective parameter for the early diagnosis of mild hepatic steatosis and evaluation of the efficacy of NAFLD treatment. (C) 2014 Baishideng Publishing Group Inc. All rights reserved.

Ultrasound-based techniques for the diagnosis of liver steatosis

Non-alcoholic fatty liver disease(NAFLD)is the leading cause of diffuse liver disease.An accurate estimate of the fat in the liver is important in the diagnostic work-up of patients with NAFLD because the degree of liver steatosis is linked to the metabolic syndrome and the cardiovascular risk.Ultrasound(US)B-mode imaging allows to subjectively estimate the fatty infiltration in the liver;however,it has a low performance for the detection of mild steatosis.Quantitative US is based on the analysis of the radiofrequency echoes detected by an US system,and it allows to calculate a backscatter coefficient or an attenuation coefficient or the sound speed.The estimation of the backscatter coefficient is rather cumbersome and requires the use of a phantom for addressing all sources of variability.Controlled attenuation parameter(CAP)available on the FibroScan system(Echosens,France)measures the attenuation of the US beam.CAP is accurate in grading fatty infiltration-even though there is an overlap between consecutive grade of liver steatosis-and the values are not influenced by liver fibrosis.Several US manufacturers are developing or have already developed software for quantifying the attenuation of the US beam.Preliminary results show that proprietary technologies implemented in US systems seem more accurate than CAP for grading liver steatosis.Another available method for quantifying liver steatosis is based on the computation of the sound speed and the initial results appear promising.

Application of contrast-enhanced ultrasound after livertransplantation:Current status and perspectives

Liver transplantation is an effective treatment for patients with end-stage liver disease. Accurate imaging evaluation of the transplanted patient is critical for ensuring that the limited donor liver is functioning appropriately. Ultrasound contrast agents(UCAs), in combination with contrastspecific imaging techniques, are increasingly accepted in clinical use for the assessment of the hepatic vasculature, bile ducts and liver parenchyma in pre-, intra- and posttransplant patients. We describe UCAs, their technical requirements, the recommended clinical indications, image interpretation and the limitations for contrastenhanced ultrasound applications in liver transplantation.

Endoscopic ultrasound guided liver biopsy for parenchymal liver disease

Liver biopsy plays an essential role in the diagnosis, evaluation and management of a vast proportion of liver diseases. Conventionally, percutaneous and transjugular approaches have been used to obtain liver biopsies. Endoscopic ultrasound guided liver biopsy(EUS-LB) has emerged as a safe and effective alternate in the past two decades. EUS-LB carries a role in evaluation of both benign and malignant diseases of the liver. It can offer higher resolution imaging of the liver and can detect smaller lesions than computed tomography scan of the abdomen or ultrasound scans with the option for doppler assistance to reduce complications. Current evidence demonstrates the superiority of EUS-LB for a targeted approach of focal lesion and there is also evidence of less sampling variability in heterogeneous parenchymal pathologies. These advantages combined with an improved safety profile had led to the rapid progress in the development of new techniques, equipment and procedures for EUS-LB. We provide a comprehensive review of EUS-LB for parenchymal liver disease.

Update on endoscopic ultrasound-guided liver biopsy

Endoscopic ultrasound guided liver biopsy(EUS-LB)has emerged as a minimally-invasive alternative to the traditional(percutaneous or transjugular)liver biopsy techniques for the diagnosis of liver parenchymal diseases.Potentially,EUS-LB combines the advantages of percutaneous and transjugular liver biopsy in addressing focused sampling in addition to measuring portal pressure.Additionally,EUS-LB facilitates access to both the lobes of the liver which is not considered with the traditional percutaneous liver biopsy.Multiple studies have compared EUS-LB with conventional liver biopsy and reported comparable diagnostic yield,increased acquisition of complete portal tracts,and longer specimen length as compared to the traditional approaches.EUS-LB is associated with lesser post-procedural pain and shorter recovery time,while providing lower risk of complications when compared to traditional liver biopsy.Innovations in needle types,needle sizes and suction techniques have aimed at further optimizing the EUS-LB technique.This review article updates current literature with focus on the variations in the technique and equipment used for EUS-LB,and compares EUS-LB with traditional methods of liver biopsy.

Differentiation of atypical hepatic hemangioma from liver metastases: Diagnostic performance of a novel type of color contrast enhanced ultrasound

BACKGROUND In clinical practice,the diagnosis is sometimes difficult with contrast-enhanced ultrasound(CEUS)when the case has an atypical perfusion pattern.Color parametric imaging(CPI)is an analysis software for CEUS with better detection of temporal differences in CEUS imaging using arbitrary colors.It measures the differences in arrival time of the contrast agent in lesions so that the perfusion features of atypical hemangioma and colorectal cancer(CRC)liver metastasis can be distinguished.AIM To evaluate the role of a novel type of CPI of CEUS in the differential diagnosis of atypical hemangioma from liver metastases in patients with a history of CRC.METHODS From January 2016 to July 2018,42 patients including 20 cases of atypical hemangioma and 22 cases of liver metastases from CRC were enrolled.These patients had a mean age of 60.5±9.3 years(range:39-75 years).All patients received ultrasound,CEUS and CPI examinations.Resident and staff radiologists independently and retrospectively reviewed CEUS and CPI images.Two sets of criteria were assigned:(1)Routine CEUS alone;and(2)CEUS and CPI.The diagnostic sensitivity,specificity,accuracy and receiver operating characteristic(ROC)curve of resident and staff radiologists were analyzed.RESULTS The following CPI features were significantly different between liver hemangioma and liver metastases analyzed by staff and resident radiologists:Peripheral nodular enhancement(65%-70.0%vs 4.5%-13.6%,P<0.001,P=0.001),mosaic/chaotic enhancement(5%-10%vs 68.2%-63.6%,P<0.001,P<0.001)and feeding artery(20%vs 59.1%-54.5%,P=0.010,P=0.021).CPI imaging offered significant improvements in detection rates compared with routine CEUS in both resident and staff groups.By resident radiologists,the specificity and accuracy of CEUS+CPI were significantly increased compared with that of CEUS(77.3%vs 45.5%,P=0.030;78.6%vs 50.0%,P=0.006).In addition,the area under the curve(AUC)of CEUS+CPI was significantly higher than that of CEUS(0.803 vs 0.757,P=0.036).By staff radiologists,accuracy was improved in CEUS+CPI(81.0%vs 54.8%,P=0.010),whereas no significant differences in specificity and sensitivity were found(P=0.144,P=0.112).The AUC of CEUS+CPI was significantly higher than that of CEUS(0.890 vs 0.825,P=0.013)by staff radiologists.CONCLUSION Compared with routine CEUS,CPI could provide specific information on the hemodynamic features of liver lesions and help to differentiate atypical hemangioma from liver metastases in patients with CRC,even for senior radiologists.

Diagnosis of liver cirrhosis with contrast-enhanced ultrasound

The assessment of the extent of liver fibrosis is very important for the prognosis and clinical management of chronic liver diseases.Although liver biopsy is the gold standard for the assessment of liver fibrosis,new non-invasive diagnostic methods are urgently needed in clinical work due to certain limitations and complications of biopsy.Noninvasive imaging studies play an important role in the diagnosis of focal liver disease and diffuse liver diseases.Among them,ultrasonography is the first choice for study of the liver in clinical work.With the development of ultrasound contrast agents and contrast specific imaging techniques,contrastenhanced ultrasound(CEUS) shows good performance and great potential in the evaluation of liver fibrosis.Researchers have tried different kinds of contrast agent and imaging method,such as arrival time of contrast agent in the hepatic vein,and quantitative analysis of the enhancement level of liver parenchyma,to evaluate the degree of liver fibrosis during the past 10 years.This review mainly summarizes the clinical studies concerning the assessment of liver fibrosis using CEUS.

Contrast-enhanced ultrasound for quantitative assessment of portal pressure in canine liver fibrosis

AIM: To explore the feasibility of non-invasive quantitative estimation of portal venous pressure by contrast-enhanced ultrasound(CEUS) in a canine model.METHODS: Liver fibrosis was established in adult canines(Beagles; n = 14) by subcutaneous injection of carbon tetrachloride(CCl4). CEUS parameters, including the area under the time-intensity curve and intensity at portal/arterial phases(Qp/Qa and Ip/Ia, respectively), were used to quantitatively assess the blood flow ratio of the portal vein/hepatic artery at multiple time points. The free portal venous pressures(FPP) were measured by a multi-channel baroreceptor using a percutaneous approach at baseline and 8, 16, and 24 wk after CCl4 injections in each canine. Liver biopsies were obtained at the end of 8, 16, and 24 wk from each animal, and the stage of the fibrosis was assessed according to the Metavir scoring system. A Pearson correlation test was performed to compare the FPP with Q p/Q a and I p/I a.RESULTS: Pathologic examination of 42 biopsies from the 14 canines at weeks 8, 16, and 24 revealed that liver fibrosis was induced by CCl4 and represented various stages of liver fibrosis, including F0(n = 3), F1(n = 12), F2(n = 14), F3(n = 11), and F4(n = 2). There were significant differences in the measurements of Qp/Qa(19.85 ± 3.30 vs 10.43 ± 1.21, 9.63 ± 1.03, and 8.77 ± 0.96) and Ip/Ia(1.77 ± 0.37 vs 1.03 ± 0.12, 0.83 ± 0.10, and 0.69 ± 0.13) between control and canine fibrosis at 8, 16, and 24 wk, respectively(all P < 0.001). There were statistically significant negative correlations between FPP and Q p/Q a(r =-0.707, P < 0.001), and between FPP and Ip/Ia(r =-0.759, P < 0.001) in the canine fibrosis model. Prediction of elevated FPP based on Q p/Q a and I p/I a was highly sensitive, as assessed by the area under the receiveroperating curve(0.866 and 0.895, respectively).CONCLUSION: C E U S i s a p o t e n t i a l m e t h o d t o accurately, but non-invasively, estimate portal venous pressure through measurement of Qp/Qa and Ip/Ia parameters.

Role of Contrast Enhanced Ultrasound in Radiofrequency Ablation of Metastatic Liver Carcinoma

Objective： To investigate the application of contrast enhanced ultrasound （CEUS） in planning and guiding for radiofrequency ablation （RFA） for metastatic liver carcinoma （MLC）. Methods： One hundred and thirty-five patients with clinically and pathologically diagnosed MLC （from gastrointestinal tumors） were included in the present study, and 104 of them had received CEUS prior to RFA to assess the number, size, shape, infiltration, location and enhancing features of the lesions. Among the 204 patients, 21 （20.1%） were excluded from RFA treatment due to too many lesions or large infiltrative range based on CEUS. The remaining 83 patients with 147 lesions underwent RFA （group A）. During the same period, other 32 patients with 202 lesions serving as control group were treated based on findings of conventional ultrasound without contrast （group B）. The patients underwent follow-up enhanced CT at the 1st month, and then every 3-6 months after RFA. The tumor was considered as early necrosis if no contrast enhancement was detected in the treated area on the CT scan at the 2st month. Results： In group A, 72 of 147 MLC lesions （48.9%） showed increased sizes on CEUS. Among them, 48 lesions （66.6%） appeared enlarged in arterial phase, and 24 （33.3%） showed enlarged hypoechoic area in parenchymal phase. CEUS showed total 61 additional lesions in 35 patients （42.2%） （ranged from 8 to 15 mm） compared with conventional ultrasound （US）, and 42 （68.8%） of them were visualized in parenchymal phase only. There were total 208 lesions in group A underwent RFA with CEUS planning, and the tumor necrosis rate was 94.2% （196/208）. In this group, local recurrence was found in 26 lesions （7.7%） during 3-42 months＇ following up, and new metastases were seen in 30 cases （36.2%）. For group B, the tumor necrosis rate was 86.3% （88/202）, local recurrence in 27 lesions （16.7%）, and new metastases in 13 cases （41.9%）. Tumor early necrosis and recurrence rates were significantly different between the two groups （P=0.018, P=0.016, respectively）. Conclusion： CEUS played an important role in RFA for liver metastases by candidate selecting and therapy planning, which helped to improve the outcome of the treatment.

Endoscopic ultrasound guided liver biopsy: Recent evidence

Liver biopsy(LB)is an essential tool in diagnosing,evaluating and managing various diseases of the liver.As such,histopathological results are critical as they establish or aid in diagnosis,provide information on prognosis,and guide the appropriate selection of medical therapy for patients.Indications for LB include evaluation of persistent elevation of liver chemistries of unclear etiology,diagnosis of chronic liver diseases such as Wilson's disease,autoimmune hepatitis,small duct primary sclerosing cholangitis,work up of fever of unknown origin,amyloidosis and more.Traditionally,methods of acquiring liver tissue have included percutaneous LB(PCLB),transjugular LB(TJLB)or biopsy taken surgically via laparotomy or laparoscopy.However,traditional methods of LB may be inferior to newer methods.Additionally,PCLB and TJLB carry higher risks of adverse events and complications.More recently,endoscopic ultrasound guided LB(EUS-LB)has evolved as an alternative method of tissue sampling that has proven to be safe and effective,with limited adverse events.Compared to PC and TJ routes,EUS-LB may also have a greater diagnostic yield of tissue,be superior for a targeted approach of focal lesions,provide higher quality images and allow for greater patient comfort.These advantages have contributed to the increased use of EUS-LB as a technique for obtaining liver tissue.Herein,we provide a review of the recent evidence of EUS-LB for liver disease.

Case of obscure-overt gastrointestinal bleeding after pediatric liver transplantation explained by endoscopic ultrasound

Portal hypertension,which is a common finding in children awaiting liver transplantation,is also found after transplantation.It's reported the case of a 6-year-old girl,transplanted for biliary atresia,who had a severe obscure-overt bleeding presenting with melena.An esophagogastroduodenoscopy showed several duodenal small,bulging lesions,with some red signs.Near the lesions,a depressed area of 2cm,covered with mixed hyperemic and white mucosa,was observed.To better evaluate these lesions,we performed an endoscopic ultrasonography(EUS) that showed multiple,round hypoechoic areas 0.5-5mm in diameter,compatible with duodenal varices,and several periduodenal anechoic lesions compatible with collaterals.A consecutive computed tomography scan showed a stenosis of the portal vein anastomosis confirmed with a transhepatic portography,which was successfully treated with balloon angioplasty.No further episodes of bleeding were observed during the follow-up.This case report suggests that EUS is safe and feasible in young children when using echoendoscopes designed for use in adults.However further studies are needed to validate the employment of this technique in the management and follow-up of pediatric portal hypertension.

Clinical Value of Contrast-enhanced Ultrasound in Differentiating Benign and Malignant Focal Liver Lesions

To explore the clinical value of contrast-enhanced ultrasound （CEUS） in differentiating benign and malignant focal liver lesions （FLLs） with SonoVue, CEUS was used to examine 113 patients with focal liver lesions （FLLs） in our hospital during July 2005 to December 2006. All the patients underwent contrast-enhanced CT （CECT） or contrast-enhanced MRI （CEMRI）. Except for patients with focal fatty sparings （n=18） and with hemangiomas （n=8）, all the patients were confirmed by operation or ultrasonic-guided liver puncture biopsy. A sulfur hexafluoride gas-based contrast agent was used with a MI of 0.15 to 0.17. Forty-eight cases of malignant FLLs, including 30 hepatocellular carcinomas （HCCs）, 2 cholangiocarcinomas and 16 metastatic tumors, were detected. Seventy-eight cases of benign FLLs, including 33 hemangiomas, 9 focal nodular hyperplasias （FNHs）, 19 focal fatty sparings, 5 abscesses, 7 regenerative nodules and 2 inflammatory pseudo-tumor, were involved. The contrast pattern of benign and malignant FLLs was quite different. CEUS has higher specificity and sensitivity than conventional ultrasound in differentiating benign and malignant FLLs.

Ultrasound-guided percutaneous microwave ablationfor small liver cancers adjacent to large vessels：long-term outcomes and strategies

Objective The aim of the study was to evaluate the long-term efficacy and safety of percutaneous microwave ablation(MWA) for small hepatic cancers adjacent to large vessels and to investigate the treatment strategies.Methods From March 2009 to July 2015,a total of 86 patients with 94 tumors underwent ultrasound(US)-guided percutaneous MWA,with pathologically proven or clinically diagnosed liver cancers measuring ≤ 3 cm in diameter and located ≤ 10 mm from a major vessel(n = 94).Regular follow-up after MWA was performed to assess treatment efficacy and perioperative complications.Results The complete ablation rate at 1 month after MWA was 93.3%(84/90).The 6-,9-,12-,24-,36-,48-,60-,72-,and 84-month local recurrence rates were 2.4%,2.4%,3.7%,6.6%,8.4%,8.4%,8.4%,8.4%,and 8.4%,respectively.There were no major complications.The perioperative special complication rate was 5.32%(5/94),including 3 cases of moderate liver function damage and 2 cases of limited sub-capsular hematoma.Conclusion Percutaneous MWA for small hepatic cancers adjacent to large vessels is feasible,effective,and safe with an acceptable rate of complications.The key point is to strictly follow operative indications and adopt proper treatment strategies.

Evaluation of fast spin echo MRI sequence for an MRI guided high intensity focused ultrasound system for in vivo rabbit liver ablation

The effectiveness of magnetic resonance imaging (MRI) to monitor thermal lesions created by High Intensity Focused Ultrasound (HIFU) in rabbit liver in vivo is investigated. The MRI sequences of T1- weighted, and T2-weighted fast spin echo (FSE) were evaluated. The main goal in this paper was to find the range of repetition time (TR) and range of echo time (TE) which maximizes the contrast to noise ratio (CNR). An ultrasonic transducer operating at 2 MHz was used, which is navigated using a positioning device. With T1W FSE the range of TR under which CNR is maximized ranges from 400 to 900 ms. The maximum contrast measured is approximately 25. With T2W FSE the range of TE that establishes maximum contrast is between 40 ms and 80 ms, with CNR of approximately 14. T1W FSE is much better than T2W FSE in detecting thermal lesions in liver. Both T1W and T2 W FSE were proven successful to image thermal lesions created by HIFU in rabbit liver in vivo.

High intensity focused ultrasound,liver disease and bridging therapy

High-intensity focused ultrasound(HIFU)is a noninvasive modality that uses an extracorporeal source of focused ultrasound energy.This technique was introduced by Lynn et al and is able to induce coagulative necrosis in selected tissues without damaging adjacent structures.Although HIFU has been studied for 50years,recent technological developments now allow its use for tumours of the liver,prostate and other sites.In liver disease,HIFU has been used to treat unresectable,advanced stages of hepatocellular carcinoma(HCC)and liver metastases.Hepatocellular carcinoma is a serious health problem worldwide and is endemic in some areas because of its association with hepatitis B and C viruses(in 20%of cases).Liver transplantation(LT)has become one of the best treatments available because it removes both the tumour and the underlying liver disease such as cirrhosis(which is present in approximately 80%of cases).The prerequisite for longterm transplant success depends on tumour load and strict selection criteria regarding the size and number of tumour nodules.The need to obtain the optimal benefit from the limited number of organs available has prompted strict selection criteria limited to only those patients with early HCC who have a better long-term outcome after LT.The so-called"bridging therapy"has the aim of controlling disease burden for patients who are on the organ transplant waiting list.Amongst various treatment options,transarterial chemoembolisation and radiofrequency ablation are the most popular treatment choices.Recently,Cheung et al demonstrated that HIFU ablation is a safe and effective method for the treatment of HCC patients with advanced cirrhosis as a bridging therapy and that it reduced the dropout rate from the liver transplant waiting list.In this commentary,we discuss the current value of HIFU in the treatment of liver disease,including its value as a bridging therapy,and examine the potential advantages of other therapeutic strategies.

Endoscopic ultrasound in common bile duct dilatation with normal liver enzymes

In recent years,the description of isolated bile duct dilatation has been increasingly observed in subjects with normal liver function tests and nonspecific abdominal symptoms,probably due to the widespread use of high-resolution imaging techniques.However,there is scant literature about the evolution of this condition and the impact of endoscopic ultrasound(EUS)in the diagnostic work up.When noninvasive imaging tests(transabdominal ultrasound,computed tomography or magnetic resonance cholangiopancreatography)fail to identify the cause of dilatation and clinical or biochemical alarm signs are absent,the probability of having biliary disease is considered low.In this setting,using EUS,the presence of pathologic findings(choledocholithiasis,strictures,chronic pancreatitis,ampullary or pancreatic tumors,cholangiocarcinoma),not always with a benign course,has been observed.The aim of this review has been to evaluate the prevalence of disease among nonjaundiced patients without signs of cytolysis and/or cholestasis and the assessment of EUS yield.Data point out to a promising role of EUS in the identification of a potential biliary pathology.EUS is a low invasive technique,with high accuracy,that could play a double cost-effective role:identifying pathologic conditions with dismal prognosis,in asymptomatic patients with negative prior imaging tests,and excluding pathologic conditions and further follow-up in healthy subjects.

High-intensity focused ultrasound ablation as a bridging therapy for hepatocellular carcinoma patients awaiting liver transplantation

The scarcity of liver grafts in Asia leads to a significant dropout of patients from liver transplant waiting lists, particularly patients with hepatocellular carcinoma and a low model for end-stage liver disease score. In order to reduce dropping out, different bridging therapies are employed. We report the use of high-intensity focused ultrasound ablation as a bridging therapy for a patient with hepatocellular carcinoma of stage two and an extremely low platelet count (20×10 9 /L). The ablation was successful. Blood tests showed that his liver function was similar before and after the treatment. No adhesion was encountered in the liver transplantation performed six months later.