Contrast-enhanced ultrasound to evaluate the severity of chronic hepatitis C

Contrast-Enhanced Ultrasonography with Arrival Time Parametric Imaging as a Non-Invasive Diagnostic Tool for Liver Cirrhosis

Liver biopsy is the gold standard method for staging liver fibrosis, but it is an invasive procedure that is associated with some complications. There are also non-invasive techniques for assessing liver fibrosis, such as elastography and biological tests, but these techniques can fail in detection or generate false measurements depending on the subject’s condition. This study aimed to determine whether liver fibrosis can be evaluated using contrast-enhanced ultrasonography with arrival time parametric imaging using the ultrasound machine’s parametric image software, the method being called (CEUS-PAT). CEUS-PAT was performed on each subject using SonoVue as a contrast agent, and images showing liver parenchyma and the right kidney on a single screen were used for analysis in parametric imaging, which was performed using the proprietary software of the ultrasound system. The ratio between the kidney and liver arrival times was calculated. The study included 64 predominantly male (56.3%) subjects, 37 cirrhotic patients, and 27 healthy volunteers, with a mean age of 58.98 ± 8.90 years. Significant differences were found between the liver cirrhosis and healthy groups regarding CEUS-PAT, 0.83 ± 0.09 vs. 0.49 ± 0.11, p < 0.0001. The correlation between CEUS-PAT and VCTE was r = 0.81. The optimal cut-off value for detecting liver cirrhosis was >0.7, with an AUC of 0.98, p < 0.001, Se = 89.19%, Sp = 100%, PPV = 100%, and NPV = 87.1%. We demonstrate that CEUS-PAT achieves excellent performance in diagnosing liver cirrhosis and is a fast method for diagnosing liver cirrhosis that can even be applied in situations where the use of other methods is excluded.

Diagnostic accuracy of hepatic vein arrival time performed with contrast-enhanced ultrasonography for HCV liver cirrhosis

BACKGROUND AND STUDY AIMS

Contrast-enhanced ultrasonography (CEUS) has increased considerably the use of ultrasound for hemodynamical analyses and quantification. Bolus injection of microbubble agents is used to evaluate transit times. This study aimed to determine the diagnostic accuracy of arrival time (seconds) to the hepatic artery (HAAT), hepatic vein (HVAT), and portal vein (PVAT), based on CEUS used for the diagnosis of cirrhosis, and to correlate these arrival times with the liver stiffness and disease severity.

PATIENTS AND METHODS

This study evaluated 29 HCV cirrhotic and 19 chronic hepatitis C patients. History, clinical examination, laboratory investigations, abdominal ultrasonography, point shear-wave elastography (pSWE), and CEUS were conducted.

RESULTS

The mean liver stiffness increased significantly in cirrhotic versus chronic HCV (22.7 versus 5.1; p-value < 0.001). The mean HAAT (p-value = 0.001), PVAT (p-value = 0.002), and HVAT values (p-value: 0.001) were significantly prolonged in cirrhotic compared with chronic HCV. The HVAT cut-off point of cirrhotic patients was 18 s with a sensitivity, specificity, and accuracy of 96.6%, 63.2%, and 83.3%, respectively (area under curve: 0.801). Significant positive correlation was found between liver stiffness (kPa) and HVAT (s) (r = 0.585; p-value = 0.005). No significant correlation was detected between HVAT (s) and the severity of liver disease, as assessed by the Child or MELD scores in cirrhotic patients.

CONCLUSION

Measuring HVAT by CEUS yielded high-accuracy and correlation outcomes for cirrhosis detection. It could be a valuable noninvasive method for the diagnosis of cirrhosis.

A New Method to Quantify Concentration of Microbubbles in Attenuating Media Using Bubble Destruction Curve Analysis of the Contrast-Enhanced Ultrasound

It is known that the microbubbles of Sonazoid are accumulated in the liver parenchyma due to the phagocytosis of Kupffer cells in the sinusoid. Because this phagocytic function decreases due to the progression of fibrosis in chronic liver disease, the deterioration of the liver function may be quantified by measuring the concentration of the accumulated Sonazoid microbubbles. In this article, a new method to quantify the concentration of microbubbles accumulated in attenuating media is proposed. This method utilizes the contrast-enhanced imaging with high mechanical index, measures the depth of the bubble destruction for each frame and analyze the shape of the destruction curve to estimate the concentration of the bubbles. A phantom experiment was performed with various concentrations of the contrast agent Sonazoid solution as well as various attenuation coefficients of the viscous media. Because of the theoretical model proposed, the estimated attenuation indexes, related to the concentration of Sonazoid microbubbles, were independent of the background attenuation of the propagating medium. The result suggest it has a potential to quantify Sonazoid concentration in the liver parenchyma more precisely against different liver attenuation conditions.

Advances in ultrasound diagnosis in chronic liver diseases

Chronic liver disease is a major disorder worldwide. A better understanding of anatomy, blood flow, and pathophysiology may be a key issue for their proper management. Ultrasound (US) is a simple and non-invasive diagnostic tool in the abdominal field. Doppler mode offers real-time hemodynamic evaluation, and the contrast-enhanced US is one of the most frequently used modalities for the detailed assessment. Further development in digital technology enables threedimensional (3D) visualization of target images with high resolution. This article reviews the wide ranges of application in the abdominal US and describes the recent progress in the diagnosis of chronic liver diseases.

Contrast-enhanced ultrasonography in chronic glomerulonephritides: correlation with histological parameters of disease activity

PURPOSE

To compare contrast-enhanced ultrasonography (CEUS)-derived time-intensity (TI) curves with histological findings in kidneys of patients affected by chronic glomerulonephritides (GN) in the early stage of disease.

METHODS

Research ethics committee approval and patient written informed consent were obtained. Thirty-one patients who showed clinical and laboratory signs of GN, with preserved renal function, were consecutively enrolled. They underwent kidney CEUS, from which TI curves were obtained, and kidney biopsy. TI curves were compared with clinical data, ultrasound (US) Doppler, and histological parameters.

RESULTS

The persistence of contrast agent signal during the wash-out phase was found to be correlated with the degree of disease activity (p = 0.016) and in particular with the presence of mesangial hyperplasia (p = 0.008). No correlation was observed between TI curves and clinical or Doppler US-derived parameters.

CONCLUSIONS

The persistence of contrast agent signal in the wash-out phase of CEUS appears to reflect a disturbance of perfusion in glomerular capillaries in the early stages of GN. We found that the histological element directly correlated with the prolonged wash-out was mesangial hyperplasia.

Imaging of nonalcoholic fatty liver disease and its clinical utility

The prevalence of nonalcoholic fatty liver disease has been continuously rising over the last three decades and is projected to become the most common indication for liver transplantation in the near future. Its pathophysiology and complex interplay with diabetes and the metabolic syndrome are not as yet fully understood despite growing scientific interest and research. Modern imaging techniques offer significant assistance in this field by enabling the study of the liver noninvasively and evaluation of the degree of both steatosis and fibrosis, and even in attempting to diagnose the presence of inflammation (steatohepatitis). The derived measurements are highly precise, accurate and reproducible, performing better than biopsy in terms of quantification. In this article, these imaging techniques are overviewed and their performance regarding diagnosis, stratification and monitoring are evaluated. Their expanding role both in the research arena and in clinical practice along with their limitations is also discussed.

Progress in non-invasive detection of liver fibrosis

Liver fibrosis is an important pathological precondition for hepatocellular carcinoma. The degree of hepatic fibrosis is positively correlated with liver cancer. Liver fibrosis is a series of pathological and physiological process related to liver cell necrosis and degeneration after chronic liver injury, which finally leads to extracellular matrix and collagen deposition. The early detection and precise staging of fibrosis and cirrhosis are very important for early diagnosis and timely initiation of appropriate therapeutic regimens. The risk of severe liver fibrosis finally progressing to liver carcinoma is >50%. It is known that biopsy is the gold standard for the diagnosis and staging of liver fibrosis. However, this method has some limitations, such as the potential for pain, sampling variability, and low patient acceptance. Furthermore, the necessity of obtaining a tissue diagnosis of liver fibrosis still remains controversial. An increasing number of reliable non-invasive approaches are now available that are widely applied in clinical practice, mostly in cases of viral hepatitis, resulting in a significantly decreased need for liver biopsy. In fact, the non-invasive detection and evaluation of liver cirrhosis now has good accuracy due to current serum markers, ultrasound imaging, and magnetic resonance imaging quantification techniques. A prominent advantage of the non-invasive detection and assessment of liver fibrosis is that liver fibrosis can be monitored repeatedly and easily in the same patient. Serum biomarkers have the advantages of high applicability (>95%) and good reproducibility. However, their results can be influenced by different patient conditions because none of these markers are liver-specific. The most promising techniques appear to be transient elastography and magnetic resonance elastography because they provide reliable results for the detection of fibrosis in the advanced stages, and future developments promise to increase the reliability and accuracy of the staging of hepatic fibrosis. This article aims to describe the recent progress in the development of non-invasive assessment methods for the staging of liver fibrosis, with a special emphasize on computer-aided quantitative and deep learning methods.

Ultrasound molecular imaging with cRGD-PLGA-PFOB nanoparticles for liver fibrosis staging in a rat model

Hepatic fibrosis is the only chronic liver disease process that can be reversed. Developing non-invasive and effective methods to quantitatively assess the degree of liver fibrosis is of great clinical significance and remains a major challenge. The key factors in hepatic fibrosis pathogenesis are the activation and proliferation of hepatic stellate cells that subsequently express integrin α_vβ₃. An ultrasound (US) agent combined with a targeting peptide may be used for the early and non-invasive diagnosis of hepatic fibrosis. Herein, we report the synthesis of core-shell nanoparticles (NPs) successfully engineered by conjugation with cyclic arginine-glycine-aspartic acid (cRGD) octapeptide, allowing hepatic integrin α_vβ₃ targeting for liver fibrosis staging. This system consists of a perfluorooctyl bromide (PFOB) liquid in the core that is stabilized with a Poly (lactic-co-glycolic acid) (PLGA) polymer shell and modified with a cRGD. These core-shell NPs (cRGD-PLGA-PFOB NPs) exhibited useful US molecular imaging features including high imaging contrast among liver fibrotic stages and the adjacent tissues. Our results indicate that the cRGD-PLGA-PFOB NPs have significant potential to distinguish different liver fibrotic stages and could be used in clinical applications.

Diagnostic Accuracy of Hepatic Vein Arrival Time Performed with Contrast-Enhanced Ultrasonography for Cirrhosis: A Systematic Review and Meta-Analysis

Background/Aims

We identified reports in the literature regarding the diagnostic accuracy of hepatic vein arrival time (HVAT) measured by contrast-enhanced ultrasonography (CEUS) to assess hepatic fibrosis in cirrhosis.

Methods

The Ovid MEDLINE, Embase, and Cochrane databases were searched for all studies published up to 23 July 2015 that evaluated liver status using CEUS and liver biopsy (LB). The QUADAS-II (quality assessment of diagnostic accuracy studies-II) was applied to assess the internal validity of the diagnostic studies. Selected studies were subjected to a meta-analysis with MetaDisc 1.4 and RevMan 5.3.

Results

A total of 12 studies including 844 patients with chronic liver disease met our inclusion criteria. The overall summary sensitivity, specificity, positive likelihood ratio, and negative likelihood ratio of the HVAT measured by CEUS for the detection of cirrhosis compared to LB were 0.83 (95% confidence interval [CI], 0.77 to 0.89), 0.75 (95% CI, 0.69 to 0.79), 3.45 (95% CI, 1.60 to 7.43), and 0.28 (95% CI, 0.10 to 0.74), respectively. The summary diagnostic odds ratio (random effects model) was 15.23 (95% CI, 3.07 to 75.47), the summary receiver operator characteristics area under the curve was 0.74 (standard error [SE]=0.14), and the index Q was 0.69 (SE=0.11).

Conclusions

Based on a systematic review, the measurement of HVAT by CEUS exhibited an increased accuracy and correlation for the detection of cirrhosis.

Evaluation of hepatic fibrosis: a review from the society of abdominal radiology disease focus panel

Hepatic fibrosis is potentially reversible; however early diagnosis is necessary for treatment in order to halt progression to cirrhosis and development of complications including portal hypertension and hepatocellular carcinoma. Morphologic signs of cirrhosis on ultrasound (US), computed tomography (CT), and magnetic resonance imaging (MRI) alone are unreliable and are seen with more advanced disease. Newer imaging techniques to diagnose liver fibrosis are reliable and accurate, and include magnetic resonance elastography and US elastography (one-dimensional transient elastography and point shear wave elastography or acoustic radiation force impulse imaging). Research is ongoing with multiple other techniques for the noninvasive diagnosis of hepatic fibrosis, including MRI with diffusion-weighted imaging, hepatobiliary contrast enhancement, and perfusion; CT using perfusion, fractional extracellular space techniques, and dual-energy, contrast-enhanced US, texture analysis in multiple modalities, quantitative mapping, and direct molecular imaging probes. Efforts to advance the noninvasive imaging assessment of hepatic fibrosis will facilitate earlier diagnosis and improve patient monitoring with the goal of preventing the progression to cirrhosis and its complications.

Hepatic vein transit time of second-generation ultrasound contrast agent: new tool in the assessment of portal hypertension

PURPOSE

It has been demonstrated that Doppler waveform of the hepatic vein (normally triphasic) is transformed into a biphasic or monophasic waveform in cirrhotic patients. The compressive mechanism of liver tissue has been considered up till now the cause of this change. Moreover, cirrhotics show, after USCA injection, a much earlier HVTT due to intrahepatic shunts. Our aim was to prospectively evaluate the correlation between Doppler pattern of hepatic vein and HVTT of a second-generation USCA; we also correlated HVTT with the most common indexes of portal hypertension.

METHODS

We enrolled 38 participants: 33 cirrhotics and 5 healthy controls. Doppler shift signals were obtained from the right hepatic vein. To characterize the hepatic vein pattern, we used the hepatic vein waveform index (HVWI). This index becomes >1 with the appearance of the triphasic waveform. We recorded a clip from 20 s before to 2 min after a peripheral intravenous bolus injection of 2.4 ml of USCA (sulfur hexafluoride).The time employed by USCA to cross the liver from the hepatic artery and portal vein to the hepatic vein was defined as HA-HVTT and PV-HVTT, respectively.

RESULTS

Cirrhotics with low HVWI showed an earlier transit time; participants with higher HVWI had a longer transit time (p < 0.001). HVTT was earlier as MELD, Child-Pugh score and spleen diameter increased. Patients with ascites and varices of large size had significantly shorter transit times.

CONCLUSIONS

Abnormal hepatic vein Doppler waveform in cirrhotic patients could be due to intrahepatic shunts. HVTT could be useful in the non-invasive evaluation of portal hypertension.

Hepatic Vein Arrival Time for Diagnosis of Liver Cirrhosis: A 10-Year Single-Center Experience With Contrast-Enhanced Sonography

OBJECTIVES

To evaluate the performance of contrast-enhanced sonography with a second-generation contrast agent in assessing the severity of chronic diffuse liver disease and differentiating cirrhotic from noncirrhotic liver disease.

METHODS

Contrast-enhanced sonography was performed after intravenous bolus injection of a second-generation contrast agent in 14 healthy control participants and 160 consecutive patients with cirrhotic and noncirrhotic liver disease (n = 78 and 82, respectively) enrolled between March 2004 and April 2014. The intensity of enhancement in a main hepatic vein was used to determine hepatic vein arrival time, time to peak intensity, and peak contrast enhancement.

RESULTS

The hepatic vein arrival time was lower in cirrhotic patients compared with both noncirrhotic patients and controls (mean ± SD, 15.0 ± 2.8, 21.5 ± 3.4, and 25.6 ± 4.7 seconds, respectively; P < .05). The hepatic vein arrival time in noncirrhotic patients was also significantly lower than that in controls (P < .05). The time to peak intensity was significantly lower in cirrhotic patients compared with noncirrhotic patients and controls (40.7 ± 13.7, 49.4 ± 12.8, and 51.2 ± 13.7 seconds; P < .05). A receiver operating characteristic curve analysis revealed that the hepatic vein arrival time more accurately excluded a diagnosis of liver cirrhosis than the time to peak intensity (area under the receiver operating characteristic curve, 0.953 versus 0.694). Specifically, a hepatic vein arrival time cutoff value of 17 seconds excluded liver cirrhosis with 91.1% sensitivity and 93.6% specificity.

CONCLUSIONS

Contrast-enhanced sonography is a valid alternative method for noninvasive staging of liver diseases. The hepatic vein arrival time could be used to exclude liver cirrhosis in a clinical setting.

Contrast-enhanced ultrasound and computerized tomography perfusion imaging of a liver fibrosis-early cirrhosis in dogs

BACKGROUND AND AIM

To assess liver fibrosis stages in a liver fibrosis-early cirrhosis model in dogs, the clinical efficiency of contrast-enhanced ultrasound (CEUS) and computed tomography (CT) perfusion imaging were compared.

METHODS

Hepatic vein arriving time (HVAT), hepatic artery arriving time, and hepatic artery to vein transit time (HA-VTT) were measured on CEUS. Total liver perfusion (TLP), portal vein perfusion (PVP), hepatic artery perfusion, and hepatic perfusion index (HPI) were measured on CT perfusion imaging. Histologic examination of liver specimens of the animals was performed to assess the fibrosis stage.

RESULTS

For assessment of liver fibrosis, the area under the receiver operating characteristic curve of CEUS indexes HVAT and HA-VTT were 0.865 and 0.930, respectively; the perfusion CT indexes TLP, PVP, and HPI were 0.797, 0.800, and 0.220, respectively; the serological index hyaluronic acid was 0.793. While for assessment of early cirrhosis, the area under the receiver operating characteristic curve of CEUS indexes HVAT and HA-VTT were 0.915 and 0.948, respectively; the perfusion CT indexes TLP, PVP, and HPI were 0.737, 0.765, and 0.218, respectively; the serological index hyaluronic acid was 0.627.

CONCLUSIONS

This study showed that both CEUS and CT perfusion imaging have the potential to be complementary imaging tools in the evaluation of liver fibrosis. While CEUS is the better choice and the index HA-VTT can be considered as non-invasive semi-quantitative indexes for diagnosing liver fibrosis and early cirrhosis.

The diagnostic value of endoscopic ultrasonography and contrast-enhanced harmonic endoscopic ultrasonography in gastrointestinal stromal tumors

Objective:

To evaluate the diagnostic value of endoscopic ultrasonography (EUS) and contrast-enhanced harmonic (CEH) EUS in patients with gastrointestinal stromal tumors (GISTs).

Patients and Methods:

About 19 patients with suspected GISTs underwent EUS and CEH-EUS before tumor resection. The malignant potential was assessed according to the modified Fletcher classification system. Patients were divided into lower (Group I) and higher (Group II) malignant potential group. The clinical characteristics and EUS/CEH-EUS features were compared between two groups.

Results:

The tumor size in Group II was significantly larger than that in Group I (14.6 ± 5.8 mm vs. 32.1 ± 8.4 mm, P < 0.05). Heterogeneous echogenicity was observed in 4 (4/8) cases in Group II and none in Group I (P < 0.05). Irregular intratumoral vessels were detected in 6 cases in Group II and none in Group I (P < 0.05). The sensitivity and specificity of irregular vessel detection for discriminating higher from lower malignant potential GISTs were 75% and 100%, respectively. The positive predictive value and negative predictive value of detection of irregular vessels to high malignant potential GISTs were 33% and 100%, respectively.

Conclusion:

Detection of irregular intratumoral vessels can predict higher malignant potential before tumor resection. The tumor size and echogenicity are assistant factors for malignant potential assessment. Endoscopic resection is an efficacious treatment with good security for appropriate patients.

Liver Function Assessment Using Parenchyma-Specific Contrast-Enhanced Ultrasonography

The aim of this study was to assess hepatic functional reserve by analyzing the hepatic parenchyma enhancement curve of parenchyma-specific contrast-enhanced ultrasonography (CEUS). Fifty-two patients with cirrhosis who underwent CEUS and indocyanine green tests (ICG) because of a focal liver lesion were enrolled. We evaluated the hemodynamic-related parameters of the time-intensity curve and compared these findings with the ICG retention rate at 15 min (ICG R15). The correlation between the time from peak to one half (s) and ICG R15 was statistically significant and was relatively proportional to the ICG R15. A cut-off value of 149 s was determined for the time from peak to one half for abnormal ICG R15 (>14). The sensitivity and specificity were 85.7% and 92.3%, respectively, for the detection of abnormal ICG R15. In conclusion, the time from peak to one half of the time-intensity curve of parenchyma-specific CEUS of the liver can be a useful parameter to predict the hepatic reserve in liver cirrhosis.

Non-invasive assessment of portal hypertension and liver fibrosis using contrast-enhanced ultrasonography

Portal hypertension and hepatic fibrosis are key pathophysiologies with major manifestations in cirrhosis. Although the degree of portal pressure and hepatic fibrosis are pivotal parameters, both are determined using invasive procedures. Ultrasound (US) is a simple and non-invasive technique that is available for use worldwide in the abdominal field. Because of its safety and easy of use, contrast-enhanced US is one of the most frequently used tools in the management of liver tumors for the detection and characterization of lesions, assessment of malignancy grade, and evaluation of therapeutic effects. This wide range of applications drives the practical use of contrast-enhanced US for evaluation of the severity of portal hypertension and hepatic fibrosis. The present article reviews the recent progress in contrast-enhanced US for the assessment of portal hypertension and hepatic fibrosis.

Potential stagnation in the splanchnic hemodynamics demonstrated by the dynamic microbubbles in chronic liver disease

BACKGROUND AND AIM

Impaired splanchnic hemodynamics are well-documented phenomena in cirrhosis. However, comprehensive hemodynamic features from the superior mesenteric artery (SMA) to the superior mesenteric vein (SMV) via intestinal capillaries have not been studied. The aim was to examine splanchnic hemodynamics and their relationship with clinical presentations.

METHODS

Contrast-enhanced ultrasound was performed for both the SMA and SMV under fasting conditions and postprandially following ingestion of a liquid diet. The microbubble traveling time (MTT) was determined as the difference between the contrast onset in the SMA and SMV, indicating the time required for microbubble transit through the splanchnic circulation.

RESULTS

There were 192 subjects for fasting conditions (81 cirrhosis, 72 chronic hepatitis, 39 healthy controls), and 74/192 for postprandial conditions (44 cirrhosis, 11 chronic hepatitis, 19 healthy controls). The MTT (fasting; postprandial) was significantly longer in cirrhosis (7.7 ± 2.9 s; 7.0 ± 0.3 s) than in controls (5.4 ± 2.3 s, P < 0.001; 3.9 ± 0.9 s, P<0.001) and chronic hepatitis (6.3 ± 2.5 s, P=0.007; 5.1 ± 1.4 s, P=0.013). The MTT ratio (postprandial/fasting) showed disease-related changes: 0.75 ± 0.20 in controls, 0.78 ± 0.15 in chronic hepatitis, and 1.00 ± 0.28 in cirrhosis (P=0.003, vs controls; P=0.036, vs chronic hepatitis).

CONCLUSIONS

The real-time observation of traveling microbubble on the sonogram revealed a prolonged transit with a weak postprandial response in the intestinal circulation, suggesting better understanding of underlying pathophysiology of splanchnic hemodynamics in chronic liver disease.

Contrast-enhanced ultrasonography for the evaluation of liver fibrosis after biliary obstruction

AIM: To investigate perfusion change in contrast-enhanced ultrasonography (CEUS) to evaluate liver fibrosis based on biliary obstruction using an animal model.

METHODS: New Zealand white rabbits (3-4 kg) underwent bile duct ligation to form a biliary obstruction model. We performed liver CEUS and laboratory tests on the day before the operation (day 0) and every 7 postoperative days until the rabbits were sacrificed. After CEUS, signal intensity of liver parenchyma with a time-intensity curve was analyzed. Perfusion parameters were automatically calculated from region-of-interests, including peak signal intensity, mean transit time, area under the curve and time to peak. Histological grades of liver fibrosis were assessed according to the Metavir score system immediately after sacrifice. Generalized estimating equations were used to analyze the association between liver fibrosis grades and perfusion parameters for statistical analysis. The perfusion parameters were measured on the last day and the difference between day 0 and the last day were evaluated.

RESULTS: From the nine rabbits, histological grades of liver fibrosis were grade 1 in one rabbit, grade 2 and 3 in three rabbits each, and grade 4 in two rabbits. Among the four CEUS parameters, only the peak signal intensity measured on the last day demonstrated a significant association with liver fibrosis grades (OR = 1.392, 95%CI: 1.114-1.741, P = 0.004). The difference in peak signal intensity between day 0 and the last day also demonstrated an association with liver fibrosis (OR = 1.191, 95%CI: 0.999-1.419, P = 0.051). The other parameters tested, including mean transit time, area under the curve, and time to peak, showed no significant correlation with liver fibrosis grades.

CONCLUSION: This animal study demonstrates that CEUS can be used to evaluate liver fibrosis from biliary obstruction using peak signal intensity as a parameter.

Imaging modalities for the diagnosis of hepatic fibrosis and cirrhosis

Non-invasive methods for liver fibrosis diagnosis are now commonly used as first-intention tests for liver fibrosis diagnosis in chronic liver diseases. Even morphological parameters provided by ultrasound is now challenged by blood fibrosis tests and transient elastography, in experienced hands, it performed well and in certain situations, imaging can still be useful to detect patients with fibrosis. In parallel, to ultrasound and Doppler imaging, various methodologies have been explored. Some of them remain confined to clinical research for the moment, as perfusion, MR diffusion-weighted imaging, intravoxel incoherent motion or acoustic structure quantification; others have already taken a place in clinical practice. Regarding fast growing of new technology some methods may become available for daily practice in the near future. Ultrasound tools or automated quantification of different physical parameters of imaging data could provide an opportunity for early diagnosis of liver diseases; MRI techniques could lead to the development of a "global" liver examination.

Contrast-enhanced sonography for quantitative assessment of portal hypertension in patients with liver cirrhosis

OBJECTIVES

The clinical utility of contrast-enhanced sonography in portal hypertension remains unclear. We explored the feasibility of using contrast-enhanced sonography for noninvasive assessment of portal venous pressure.

METHODS

Twenty healthy individuals (control group; 9 men; mean age, 46.4 years) and 18 patients with portal hypertension (15 men; mean age, 46.2 years) were enrolled in this study. The portal hypertension group included patients who underwent splenectomy and pericardial blood vessel disarticulation at our hospital from October 2010 to March 2011. One week before surgery, patients with portal hypertension underwent preoperative liver contrast-enhanced sonography. Two-dimensional, Doppler, and contrast-enhanced sonographic parameters were compared between the groups. Portal venous pressure was measured intraoperatively by portal vein puncture in the portal hypertension group, and its relationship with the other parameters was analyzed.

RESULTS

The 2-dimensional, Doppler, and contrast-enhanced sonographic parameters differed between the groups (P < .01). Portal venous pressure was inversely correlated with the area under the portal vein/hepatic artery time-intensity curve ratio (Qp/Qa), portal vein/hepatic artery strength ratio (Ip/Ia), and portal vein/hepatic artery wash-in perfusion slope ratio (βp/βa), with correlation coefficients of -0.701, -0.625, and -0.494, respectively.

CONCLUSIONS

Measurement of the liver contrast-enhanced sonographic parameters Qp/Qa, Ip/Ia, and βp/βa could be used as a new quantitative method for noninvasively assessing portal venous pressure.

Functional imaging of the liver

Anatomical-based imaging is used widely for the evaluation of diffuse and focal liver, including detection, characterization, and therapy response assessment. However, a limitation of anatomical-based imaging is that structural changes may occur relatively late in a disease process. By applying conventional anatomical-imaging methods in a more functional manner, specific pathophysiologic alterations of the liver may be assessed and quantified. There has been an increasing interest in both the clinical and research settings, with the expectation that functional-imaging techniques may help solve common diagnostic dilemmas that conventional imaging alone cannot. This review considers the most common functional magnetic resonance imaging, computed tomography, and ultrasound imaging techniques that may be applied to the liver.

Guidelines and good clinical practice recommendations for Contrast Enhanced Ultrasound (CEUS) in the liver - update 2012: A WFUMB-EFSUMB initiative in cooperation with representatives of AFSUMB, AIUM, ASUM, FLAUS and ICUS

Initially, a set of guidelines for the use of ultrasound contrast agents was published in 2004 dealing only with liver applications. A second edition of the guidelines in 2008 reflected changes in the available contrast agents and updated the guidelines for the liver, as well as implementing some non-liver applications. Time has moved on, and the need for international guidelines on the use of CEUS in the liver has become apparent. The present document describes the third iteration of recommendations for the hepatic use of contrast enhanced ultrasound (CEUS) using contrast specific imaging techniques. This joint WFUMB-EFSUMB initiative has implicated experts from major leading ultrasound societies worldwide. These liver CEUS guidelines are simultaneously published in the official journals of both organizing federations (i.e., Ultrasound in Medicine and Biology for WFUMB and Ultraschall in der Medizin/European Journal of Ultrasound for EFSUMB). These guidelines and recommendations provide general advice on the use of all currently clinically available ultrasound contrast agents (UCA). They are intended to create standard protocols for the use and administration of UCA in liver applications on an international basis and improve the management of patients worldwide.

Contrast-enhanced ultrasound evaluation of hepatic microvascular changes in liver diseases

AIM: To assess if software assisted-contrast-enhanced ultrasonography (CEUS) provides reproducible perfusion parameters of hepatic parenchyma in patients affected by chronic liver disease.

METHODS: Forty patients with chronic viral liver disease, with (n = 20) or without (n = 20) cirrhosis, and 10 healthy subjects underwent CEUS and video recordings of each examination were then analysed with Esaote’s Qontrast software. CEUS dedicated software Qontrast was used to determine peak (the maximum signal intensity), time to peak (TTP), region of blood value (RBV) proportional to the area under the time-intensity curve, mean transit time (MTT) measured in seconds and region of blood flow (RBF).

RESULTS: Qontrast-assisted CEUS parameters displayed high inter-observer reproducibility (κ coefficients of 0.87 for MTT and 0.90 TTP). When the region of interest included a main hepatic vein, Qontrast-calculated TTP was significantly shorter in cirrhotic patients (vs non-cirrhotics and healthy subjects) (71.0 ± 11.3 s vs 82.4 ± 15.6 s, 86.3 ± 20.3 s, P < 0.05). MTTs in the patients with liver cirrhosis were significantly shorter than those of controls (111.9 ± 22.0 s vs 139.4 ± 39.8 s, P < 0.05), but there was no significant difference between the cirrhotic and non-cirrhotic groups (111.9 ± 22.0 s vs 110.3 ± 14.6 s). Peak enhancement in the patients with liver cirrhosis was also higher than that observed in controls (23.9 ± 5.9 vs 18.9 ± 7.1, P = 0.05). There were no significant intergroup differences in the RBVs and RBFs.

CONCLUSION: Qontrast-assisted CEUS revealed reproducible differences in liver perfusion parameters during the development of hepatic fibrogenesis.

Heterogeneous staining in the liver parenchyma after the injection of perflubutane microbubble contrast agent

This study aimed to characterize the features of heterogeneous staining in the liver after injection of perflubutane microbubble agent (Sonazoid(TM), 0.0075 mL/kg). Digitized hepatic contrast sonograms from 906 subjects were reviewed to assess time-related changes in heterogeneous staining and the possible association between this effect and the clinical backgrounds was analyzed. Heterogeneous staining was found in seven subjects (0.77%) on 15-min phase sonograms. The staining initially appeared as hyper-enhanced circular spots in the liver 10 min or later after the agent injection. The number of spots increased gradually with unequally-spaced distribution. Although the staining pattern did not improve during the examination, there were no abnormal findings in vital signs or symptoms on the day and blood test results or sonograms on the following day. Heterogeneous staining is a side effect that impedes ultrasound examination. However, at present, the precise causes and underlying mechanisms of this event are unknown.

Accuracy and reliability of microbubble ultrasound measurements for the non-invasive assessment of hepatic fibrosis in chronic hepatitis C

AIM

  Contrast-enhanced ultrasound can be used to assess liver disease severity non-invasively by observing intra- and extrahepatic hemodynamic changes. Transit times are calculated to include intra- and extrahepatic components (hepatic vein transit time, HVTT) or the intrahepatic component (hepatic transit time, HTT), but these have not been compared directly. We aimed to compare diagnostic accuracy of HVTT and HTT in gauging the severity of chronic hepatitis C (CHC) and to assess inter- and intra-observer reliability.

METHODS

  Recorded ultrasound scans performed on 75 patients with biopsy-staged CHC, using the microbubble contrast agent Sonovue were analyzed.

RESULTS

  Diagnostic accuracy of HTT and HVTT for diagnosis of cirrhosis was 0.78 and 0.71 (P = 0.24). Diagnostic accuracy of HTT and HVTT for diagnosis of fibrosis stage >2 was 0.76 and 0.72 (P = 0.23). Negative predictive value for cirrhosis using this cut-off was high for both techniques (HVTT, 88%; HTT, 92%), suggesting utility for exclusion of cirrhosis. Inter-observer reliability for HTT and HVTT were 0.92 and 0.94, respectively. Intra-observer reliability for HTT and HVTT were 0.98 and 0.99.

CONCLUSION

  In this cohort, reliability exceeded 90% while diagnostic accuracy was in keeping with previous studies of microbubble transit time analysis. Despite higher numerical diagnostic accuracy for HTT, no significant difference was demonstrated between the techniques, suggesting that both methods can be used reliably.

Assessment of portal venous index as a non-invasive method for diagnosing liver fibrosis in patients with chronic hepatitis C

CONTEXT: Hepatitis C is an important cause of chronic liver disease worldwide. The grading of hepatic fibrosis in chronic hepatitis C is important for better clinical management. However, until now, liver biopsy is the only test accepted for this purpose, despite their contraindications and complications. New methods for non-invasive assessment of hepatic fibrosis are under investigation. One proposal is the Doppler ultrasound, as a non-invasive, widely available and inexpensive. OBJECTIVE: To compare Doppler parameters of portal vein in patients with chronic hepatitis C with a healthy control group and to correlate these parameters with fibrosis degree obtained by liver biopsy. METHODS: Fifty patients with chronic hepatitis C submitted to liver biopsy and 44 healthy controls had Doppler of the portal vein performed, with the calculation of the portal venous index. We conducted a comparison between the averages of the two groups of portal venous index. For the correlation between portal venous index and fibrosis was employed the Spearman test. RESULTS: There was a difference between the average portal venous index between controls (0.33 ± 0.07) and patients (0.23 ± 0.09) with P<0.001. No difference was observed between the portal venous index in patients with chronic hepatitis C who have significant fibrosis or not. The correlation between the portal venous index and fibrosis degree was reverse and moderate (r =-0.448 P<0.001). The area under the ROC curve was 78.4% (95% CI: 68.8% to 88%). The cutoff for the portal venous index was 0.28 with sensitivity of 73.5% and specificity of 71.1%. CONCLUSION: The portal venous index was useful in distinguishing healthy patients from patients with CHC. However, there was no significant difference in the quantification of degree of fibrosis.

Demonstration of intrahepatic accumulated microbubble on ultrasound represents the grade of hepatic fibrosis

Objectives

To examine the feasibility of perflubutane-based ultrasound for grading hepatic fibrosis.

Methods

This prospective study included 202 subjects; main study (controls:33, F0–1:35, F2:26, F3:23, cirrhosis:29) and subsequent study (controls:16, F0–1:7, F2:20, F3:7, cirrhosis:6). Diagnostic abilities for assessing fibrosis grade were compared between contrast findings and FIB4 (age × AST/[platelet count × ALT^0.5]).

Results

High-power emission produced an intrahepatic band-like structure, and the three-layer appearance was less frequent and monolayer appearance was more frequent in cirrhosis than controls/chronic hepatitis (P < 0.0001). Intensity difference at 15-min phase showed most significant correlation with fibrosis grade (ρ = 0.79, P < 0.0001), and the best areas under the receiver operating characteristic curves are 0.88 for marked fibrosis, 0.95 for advanced fibrosis and 0.97 for cirrhosis, which were significantly higher than those of FIB4, 0.85 for marked fibrosis, 0.89 for advanced fibrosis and 0.90 for cirrhosis. Sensitivity, specificity and efficiency of the intensity difference were 88%, 72% and 81% for marked fibrosis, 85%, 91% and 89% for advanced fibrosis and 97%, 90% and 91% for cirrhosis, respectively. The subsequent study validated the main study results; significant correlation between the intensity difference and the fibrosis grade (ρ = 0.73–0.77, P < 0.0001).

Conclusions

Perflubutane-based ultrasound accurately predicts the grade of hepatic fibrosis.

Key Points

• The behaviour of intrahepatic microbubbles depends on the severity of hepatic fibrosis.

• Layer enhancement pattern simply represents the degree of chronic liver disease.

• Parenchymal intensity change due to high-power emission predicts the hepatic fibrosis grade.

Does hepatic vein transit time performed with contrast-enhanced ultrasound predict the severity of hepatic fibrosis?

Previously published data suggest a hepatic vein transit time (HVTT) threshold of more than 24 s can distinguish mild to moderate from advanced fibrosis. In this study, we attempted to validate HVTT as a noninvasive index of hepatic fibrosis. Patients were scanned using real-time, pulse-inversion mode following bolus injections of the contrast agent Definity. HVTT was correlated with the degree of fibrosis obtained from contemporaneous liver biopsy. The study population included 40 patients with chronic liver disease and five healthy volunteers. Mean HVTT correlated with histologic grade as follows: absence/minimal fibrosis (n = 18), 25.6 ± 11.8 s; moderate fibrosis (n = 17), 21.5 ± 5.9 s; and severe fibrosis (n = 8), 20.9 ± 5.5 s, (p = .615). Poor sensitivity (57%) and specificity (43%) prevent validation of the previously published HVTT threshold as a surrogate marker of hepatic fibrosis. Further work investigating the different interaction of Definity, SonoVue and Levovist with the reticulo-endothelial system may help explain the discrepant results reported here.

Contrast-enhanced ultrasonography using Sonazoid to evaluate changes in hepatic hemodynamics in acute liver injury

BACKGROUND AND AIMS

Disturbances in hepatic microcirculation are believed to be involved in the mechanisms regulating the progression of acute liver injury (ALI). Evaluation of hepatic hemodynamics in patients with acute liver injury might be helpful in understanding the extent of the intrahepatic microcirculatory disturbances. Therefore, we investigated whether contrast-enhanced ultrasonography (CEUS) is useful to evaluate the changes in hepatic hemodynamics in patients with ALI.

METHODS

CEUS was performed in 21 patients with ALI and coagulopathy. Participants were injected with 0.0075 mL Sonazoid/kg body weight, and time-intensity curves were simultaneously recorded for the hepatic and portal veins. The data were compared with those of 10 healthy volunteers.

RESULTS

The arrival time of Sonazoid in the hepatic vein was similar to that in the portal vein in the patients, whereas the arrival time in the hepatic vein was delayed relative to that in the portal vain in the controls (interval between the hepatic and portal vein arrival times, control vs patients 6.74 ± 3.07 s vs 1.13 ± 1.07 s, P < 0.001). Repeated examination revealed that the interval between the hepatic and portal vein arrival times was extended by improvements in hepatic function. The early arrival of Sonazoid in the hepatic vein in the patients is likely to reflect the formation of intrahepatic shunts as a result of hepatic microcirculatory disturbances.

CONCLUSION

CEUS using Sonazoid is a useful method to estimate the changes in hepatic hemodynamics in patients with ALI.

Noninvasive analysis of portal pressure by contrast-enhanced sonography in patients with cirrhosis

OBJECTIVES

Free portal pressure measurement is a reliable method for assessment of portal pressure in patients with cirrhosis. Intrahepatic circulatory time analysis of a sonographic contrast agent can assess liver fibrosis and its severity. The purposes of this pilot study were to assess the correlation between the intrahepatic circulatory time and free portal pressure and to assess whether intrahepatic circulatory time analysis can be used to predict portal venous pressure severity.

METHODS

The intrahepatic circulatory time and free portal pressure were measured in 31 patients with hepatitis B virus-related liver disease. Pearson correlation analysis was used to assess the correlation between the intrahepatic circulatory time and free portal pressure.

RESULTS

The hepatic vein-hepatic artery interval times were significantly shorter in the portal hypertension group than the non-portal hypertension group (mean ± SD, 8.26 ± 1.94 and 13.83 ± 1.17 seconds, respectively; P < .001). The portal vein-hepatic artery interval times were significantly longer in the portal hypertension group than the nonportal hypertension group (13.13 ± 2.25 and 7.25 ± 1.81 seconds; P < .001). Considering the whole patient population, there were statistically significant correlations between free portal pressure and the hepatic vein-hepatic artery interval time (r = -0.900; P < .001) and portal vein-hepatic artery interval time (r = 0.808; P < .001). In patients with portal hypertension, there was a statistically significant correlation between free portal pressure and the hepatic vein-hepatic artery interval time (r = -0.804; P = .009) and a weak correlation between free portal pressure and the portal vein-hepatic artery interval time (r = 0.506; P = .036).

CONCLUSIONS

Intrahepatic circulatory time measurement is correlated with free portal pressure and has the potential capability to evaluate portal pressure noninvasively in patients with hepatitis B virus-related liver disease.

Liver contrast enhanced ultrasound perfusion imaging in the evaluation of chronic hepatitis C fibrosis: preliminary results

We wanted to determine whether liver contrast-enhanced ultrasound (CEUS)-derived peak signal intensity (PSI) and peak signal intensity/time (PIT) predict liver fibrosis in chronic hepatitis C (CHC). Forty-nine patients with CHC (METAVIR classification) and 10 control subjects were included in the study. After a bolus of 2.4 mL SonoVue (Bracco Imaging, Milan, Italy) solution was injected into a peripheral vein, the right lobe of the liver containing the right portal vein was scanned in a transverse section. Two-dimensional sonography was performed using the Philips iU22 ultrasound system (Philips Healthcare, Best, the Netherlands). A 1.0-5.0-MHz (C5-1) wideband convex transducer was used, applying the following settings in all cases. Regions of interest were manually drawn over the right liver lobe and over the portal vein (PV). Liver parenchyma PSI (LPpsi) and PIT (LPpit), portal vein PSI (PVpsi) and PIT (PVpit) were automatically calculated. δPSI was defined as the difference between PVpsi and LPpsi. A significant correlation was observed between PA(PSI) and fibrosis scores. When patients were stratified according to their LPpsi, a significant difference was achieved only between patients with fibrosis score 0-1 vs. 2-3 and 2 vs. 4. Statistically significant differences between all fibrosis scores, except 0 vs. 1 and 3 vs. 4 were observed when δPSI was used to stratify patients. Overall diagnostic accuracy of LPpsi and δPSI measurement for severe fibrosis by area under the receiving operator characteristic curve analysis was, respectively, 0.87 and 0.88. We suggest that liver CEUS perfusion could have the potential to be used as a complementary tool for the evaluation of liver fibrosis. However, further large-scale studies are required to accurately assess its accuracy in the evaluation of liver fibrosis.

Imaging of perfusion using ultrasound

Ultrasound can be used to image perfusion in two ways: the traditional one using Doppler and the more recent using microbubble contrast agents. Doppler is simple to use and inexpensive but is limited to larger vessels with faster flow rates. It cannot interrogate the microvasculature because bulk tissue movement is faster than capillary flow. It has been used for liver and tumour flow. Contrast studies are much richer and can assess both the macro- and microcirculation. One approach analyses the time-intensity curves in a region of interest, e.g. a tumour, myocardium, brain, following bolus i.v. injection. Another approach measures the time taken for the microbubbles to cross a vascular bed of interest. These arrival times can be useful for the liver in both diffuse and focal diseases and for the kidney. Features derived from time-intensity curves following bolus i.v. injections of microbubbles form sensitive early indicators of the vascular response of tumours to antivascular drugs. This approach, known as dynamic contrast-enhanced ultrasound (DCE-US), has been accepted as a valid technique for monitoring tumour response by several authorities.

Optimal combinations of ultrasound-based and serum markers of disease severity in patients with chronic hepatitis C

Combinations of noninvasive markers may improve discrimination of chronic liver disease severity. The aims of this study were to compare four validated serum and ultrasound-based markers of hepatic disease severity head-to-head with liver biopsy and to assess optimal combinations with consideration of cost. A total of 67 patients with biopsy-proven chronic hepatitis C underwent all four techniques on the same visit [aspartate aminotransferase (AST) to platelet ratio index (APRI); Enhanced Liver Fibrosis (ELF) panel; transient elastography (TE) and ultrasound microbubble hepatic transit times (HTT)]. Markers were combined according to increasing financial cost and ordinal regression used to determine contributions. APRI, ELF, TE and HTT predicted cirrhosis with diagnostic accuracy of 86%, 91%, 90% and 83% respectively. ELF and TE were the most reliable tests with an intra-class correlation of 0.94 each. Either ELF or TE significantly enhanced the prediction of fibrosis stage when combined with APRI, but when combined together, did not improve the model further. Addition of third or fourth markers did not significantly improve prediction of fibrosis. Combination of APRI with either ELF or TE effectively predicts fibrosis stage, but combinations of three or more tests lead to redundancy of information and increased cost.

Intrahepatic transit time predicts liver fibrosis in patients with chronic hepatitis B: quantitative assessment with contrast-enhanced ultrasonography

We investigated the use of contrast-enhanced ultrasonography (CEUS) with quantitative measurements to assess the stages of liver fibrosis in patients with chronic hepatitis B. One-hundred twenty-two patients with chronic hepatitis B were divided into three groups according to the Scheuer scoring system pathologically and according to clinical evidence: mild fibrosis (S0 and S1, n = 36); moderate fibrosis (S2 and S3, n = 24); and cirrhosis (S4 and clinically typical cirrhosis, n = 62). CEUS of hepatic vessels and parenchyma was performed using the Cadence contrast pulse sequencing technique, with an intravenous bolus injection of a contrast agent (SonoVue). Real-time CEUS imaging of the liver was recorded and analyzed offline. Contrast arrival time, baseline, and peak intensity in the hepatic artery, portal vein, right hepatic vein, and liver parenchyma were used to calculate intrahepatic transit times, hepatic artery to hepatic vein transit time (HA-HVTT) and portal vein to hepatic vein transit time (PV-HVTT), as well as increased signal intensity (ISI). The correlations between these quantitative parameters and the stages of fibrosis were analyzed using Spearman rank correlation coefficients. HA-HVTT and PV-HVTT were shortened gradually with the progression of liver fibrosis. PV-HVTT was statistically significant differences existed between the two paired groups (mild vs. moderate vs. cirrhosis groups, p < 0.001), whereas HA-HVTT was changed significantly between mild and moderate or cirrhosis groups (p < 0.001). HA-HVTT and PV-HVTT changes were significantly correlated with liver fibrosis severity (r = -0.5930, p < 0.001; r = -0.8215, p < 0.001). Area under receiver operating characteristic curves for HA-HVTT and PV-HVTT were 0.891 +/- 0.034 and 0.955 +/- 0.020 at fibrosis scores >or=S2, and 0.785 +/- 0.040 and 0.946 +/- 0.018 at fibrosis score >or=S4, respectively. ISI values in the portal vein and liver parenchyma decreased with the severity of fibrosis. This study demonstrated that hepatic CEUS with quantitative measurements of intrahepatic transit time reflected the severity of liver fibrosis. The real-time CEUS imaging with use of software-based quantitative analysis could provide reliable information of hepatic hemodynamic changes to noninvasively assess the severity of liver fibrosis in patients with chronic hepatitis B.

Advances in ultrasonic diagnosis of hepatic fibrosis and early cirrhosis

With the development of medical ultrasonic technology, sonography has become an important means for diagnosis and evaluation of hepatic fibrosis and early cirrhosis. Two-dimensional sonography is the basic means of ultrasonic diagnosis and can be used to display the appearance and echo of the liver. Color Doppler sonography and Doppler frequency spectrum permit assessment of the portal venous system and detection of portal blood flow. They can be used not only for estimation of hepatic parenchymal changes but also for evaluation of portal hypertension and its complications. Contrast-enhanced ultrasound permits use of a blood-pool tracer and can assess the blood flow perfusion of hepatic parenchyma. Elasticity imaging indirectly reflects tissue pathological changes by measuring tissue elastic modulus. Fibroscan has shown great promise for staging and diagnosing hepatic fibrosis and monitoring the development of hepatic cirrhosis and portal hypertension, thus offering a new method for noninvasive diagnosis of hepatic diseases. The clinical application of these techniques has greatly improved the diagnosis of hepatic diseases. In this article, we will review the recent advances in ultrasonic diagnosis of hepatic fibrosis and early cirrhosis.

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, contrast-enhanced 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.

Liver fibrosis staging with contrast-enhanced ultrasonography: prospective multicenter study compared with METAVIR scoring

We prospectively assessed contrast-enhanced sonography for evaluating the degree of liver fibrosis as diagnosed via biopsy in 99 patients. The transit time of microbubbles between the portal and hepatic veins was calculated from the difference between the arrival time of the microbubbles in each vein. Liver biopsy was obtained for each patient within 6 months of the contrast-enhanced sonography. Histological fibrosis was categorized into two classes: (1) no or moderate fibrosis (F0, F1, and F2 according to the METAVIR staging) or (2) severe fibrosis (F3 and F4). At a cutoff of 13 s for the transit time, the diagnosis of severe fibrosis was made with a specificity of 78.57%, a sensitivity of 78.95%, a positive predictive value of 78.33%, a negative predictive value of 83.33%, and a performance accuracy of 78.79%. Therefore, contrast-enhanced ultrasound can help with differentiation between moderate and severe fibrosis.

Can imaging modalities diagnose and stage hepatic fibrosis and cirrhosis accurately?

The accurate diagnosis and staging of hepatic fibrosis is crucial for prognosis and treatment of liver disease. The current gold standard, liver biopsy, cannot be used for population-based screening, and has well known drawbacks if used for monitoring of disease progression or treatment success. Our objective was to assess performance and promise of radiologic modalities and techniques as alternative, noninvasive assessment of hepatic fibrosis. A systematic review was conducted. Six hundred twenty-eight studies were identified via electronic search. One hundred fifty-three papers were reviewed. Most described techniques that could differentiate between cirrhosis or severe fibrosis and normal liver. Accurate staging of fibrosis or diagnosis of mild fibrosis was often not achievable. Ultrasonography is the most common modality used in the diagnosis and staging of hepatic fibrosis. Elastographic measurements, either ultrasonography-based or magnetic resonance-based, and magnetic resonance diffusion weighted imaging, show the most promise for accurate staging of hepatic fibrosis. Most currently available imaging techniques can detect cirrhosis or significant fibrosis reasonably accurately. However, to date only magnetic resonance elastography has been able to stage fibrosis or diagnose mild disease. Utrasonographic elastography and magnetic resonance diffusion weighted appear next most promising.

Ultrasound Contrast Agents in the Study of Kidney Function in Health and Disease

Ultrasound contrast agents are gas filled microbubbles that enhance the ultrasound image. They behave similarly to red blood cells and cross all capillary beds; making contrast enhanced ultrasonography (CEU) a suitable technique to study vasculature and tissue blood flow. Ultrasound contrast agents have been found to be safe after intravenous injection. CEU has been used extensively in the field of cardiology. Currently, study of renal vasculature and renal blood flow requires complicated, time consuming and expensive techniques, which are not commonly used in clinical settings. CEU potentially may serve as a relatively noninvasive and safe technique for studying renal hemodynamics in health and disease. In this article we have reviewed the literature on the use of CEU in the study of kidney disease.