Hepatic Fibrosis: US and MR Elastography

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Ultrasound in Medicine and Biology

and functional recovery was reported although the number of cases is small. Local ablative modalities such as radiofrequency ablation (RFA) or photodynamic therapy (PDT) are also applied to pancreas in animal studies. For pain management, EUS-guided celiac plexus block or neurolysis are tried and showed pain response. In conclusion, EUS became an indispensable tool for the diagnosis and management of pancreatic disease and will play a key role in the treatment of benign and malignant pancreatic disease in the future. Symposium T12-14-IN01 Elastography Application in Liver Pathology: between Expectations and Result Adrian S aftoiu Research Center of Gastroenterology and Hepatology, University of Medicine and Pharmacy Craiova, Romania The term ‘‘elastography’’ describes an imaging technique that generates information about the stiffness of tissues, being a method that is related more to palpation than inspection. Several commercial systems are currently available and various types of elastography have been used clinically. Thus, transient elastography, strain elastography, acoustic radiation force impulse (ARFI) imaging, point shear wave elastography, 2D and 3D shear wave elastography have been used in various liver applications. The assessment of fibrosis in chronic liver diseases is important for both the prognosis and management of the patients, including decisions for antiviral therapy. Transient elastography can be used as first line assessment for the severity of liver fibrosis, in chronic hepatitis C, but also in chronic hepatitis B. It can be used to exclude cirrhosis in non-alcoholic fatty liver disease, as well as in alcoholic liver disease. Due to the intrinsic variability of the method, ten measurements should be obtained. Strain elastography is a qualitative method based on tissues grade compression to a generated force, considering that the tissue deformation is smaller in hard tissue as compared to soft tissue. To improve the reproducibility of elastography, second-generation devices allow for semi-quantitative analysis of tissue stiffness. There are two semiquantitative elastography methods: strain histogram and strain ratio. Elastography should not be performed without the knowledge of patient complaints, past medical history and basic laboratory testing. In conclusion, as a non-invasive method, elastography is perfectly suited for the assessment of chronic liver diseases. T12-14-IN02 Correlation Between Fibroscan and ARFI with Metavir Liver Fibrosis Score Dar-In Tai, MD, PhD Department of Gastroenterology and Hepatology, Chang Gung Memorial Hospital, at Linkou, Tao-Yuan, Taiwan Non-invasive assessment of liver fibrosis with Fibroscan and acoustic radiation force impulse (AFRI) imaging are two most popular modalities to measure liver fibrosis. Fibroscan is a well-established modality which measure both liver fibrosis and steatosis. However, there is considerable failure rate, and without image quidding the data may be misleading in the present of focal lesion in R hepatic lobe. ARFI may select an optimal location for measurement but there are concerns on the inter-observer and inter-location variations. We try to decrease the variation by measuring ARFI at two different locations. In a consecutive series of patients who received liver histology study were prospectively enrolled. All participant received hemogram, liver biochemistry, viral markers, ARFI and Fibroscan within 4 weeks of histology study. A standardized protocol was used to both Fibroscan and

Volume 43, Number S1, 2017 ARFI on the same day by a single technologist. Then both data from Fibroscan and ARFI were correlated with liver histology. Additional series of non-biopsy cases with chronic hepatitis B, chronic hepatitis C and non-alcoholic liver disease were also included for validation analysis. A total of 83 patients with liver histology study were included. This series included 34 NonB and NonC, 8 autoimmune liver diseases, 29 chronic hepatitis B and 12 hepatitis C. We excluded patients with alcoholism, dual HBV and HCV infection and unknown etiology. The correlation between Fibroscan and ARFI two-location measurement is good (R250.589, P,0.001). The area under the curve for Metavir 4 fibrosis are 0.877 and 0.919 for Fibroscan and ARFI respectively. A relatively lower value in Fibroscan than in ARFI is noted in the present of severe steatosis (CAP$293, P,0.001). Similar situation was found in non-biopsy patients received both studies. The phenomenon of lower slope in patients with high CAP value are presented in all HBV, HCV or NBNC non-biopsy groups. We conclude that the correlation between Fibroscan and ARFI two location measurement is good. ARFI tends to have a better linearity with histology fibrosis grades than Fibroscan in patients with severe steatosis. T12-14-IN03 Clinical Feasibility of Liver Elastography Kai Wen Huang Hepatitis Research Center & Department of Surgery, National Taiwan University Hospital, Taipei, Taiwan The clinical management of chronic hepatitis depends on the correct assessment of liver fibrosis. Liver biopsy is accepted as the gold standard to determine the fibrotic status, but it is invasive, and the diagnostic accuracy is strongly influenced by inter-observer variation. Therefore, noninvasive methods have been proposed, such as transient elastography (TE), real-time tissue elastography (RTE) and acoustic radiation force impulse (ARFI) Imaging. TE measures liver stiffness, which is correlated to fibrosis stage, and recent meta-analyses have shown high accuracy in the diagnosis of liver cirrhosis. This method, however, has several limitations: failure or unreliable results occur in 10–20% of patients due to the patient being overweight, narrow intercostal spaces, or high variability of measurements. New methods for assessing liver fibrosis have been proposed and are now under evaluation. RTE and ARF imaging technology are two different add-on modules that can be embedded into standard ultrasound imaging devices. They both measure liver stiffness and have the advantage of combining direct visualization of the liver parenchyma and liver stiffness measurements. This enables the operator to directly correlate the anatomical correspondence between tissue elasticity and B-mode display, thus avoiding the subcapsular region and reducing the variability of measurements. The results are not affected by overweight patient status or narrow intercostal spaces. Early studies have shown that the results of both techniques are reproducible and correlate with liver fibrosis. The aim of this present was to perform a direct comparison of these techniques in diagnosing fibrosis in the population consisting of normal subjects and patients with liver fibrosis. T12-14-IN04 Hepatic Fibrosis: US and MR Elastography Byung Ihn Choi, MD Radiology, Chung-Ang University Hospital, Seoul, Korea Hepatic fibrosis is final results of a wide variety of types of liver ingury and is a consequence of all chronic liver diseases and progresses more or less rapidly towards cirrhosis, and finally cancer. In terms of the tools used to quantitate fibrosis today, there are three kinds of tools; biochemical markers, conventional imaging, and functional imaging such as elastography (E) or stiffness imaging. Recent

Abstracts imaging tools for evaluation of hepatic fibrosis are US based techniques, MR based techniques, and perfusion imaging. US Elastography (USE) is classified into strain-based E and SW-based E. Strain-based E is subclassified into Static USE (Manual compression of the tissue) and Quasi-static USE (Physiologic vibrations (heartbeat, blood vessels pulse). SW-based E is subclassified into 1D such as fibroscan (Echosens), Point E such as virtual touch quantification (Siemens). ElastPQ (Philips) and 2D SWE such as supersonic shear imaging (Supersonic Imagine), and shear wave elastography (GE, Toshiba)). For the liver, USE is divided into 2 categories quasi-static E and shear wave based imaging. Quasi-static E is not popular. Shear wave based imaging is subdivided into two types based on generation method of shear wave: Controlled ernal vibration with a vibrator and acoustic radiation force impulse. Transient elastography is using mechanical push, and both ARFI imaging and supersonic shear wave elastography are using ARFI. Strengths of 1D SW-based elastography are the most extensively investigated technique with high portablility. Limitations are no B-mode imaging, high technical failure rate (2.4-9.4%) and narrow applications outside of liver investigation. Strengths of point SW-based elastography are low technical failure rate (, 1%), very short acquisition time and extensively investigated technique. Limitations are small ROI and greater energy absorption. Strengths of 2D SW-based elastography are larger ROI, which may reduce sampling variability, real time and 2D elastogram. Limitations are 2-3% technical failure, longer acquisition time, hyper sensitivity for tissue attenuation and motion. Then, which elastography technique should be used? Or how to choose? USE is better than MRE in terms of convenience, acquisition time, cost, and availability. But, MRE is better than USE in terms of sample volume, technical failure, and multiparametric evaluation. Limitations of elastography are many confounders in stiffness measurements, such as inflammation, portal pressure, right heart pressure, and cholestasis and so on, and both techniques of USE and MRE need further standardization. Therefore, other comprehensive imaging techniques are needed, such as DWI or DCE –US or MR. In Summary, liver stiffness is determined by matrix deposition (fibrosis) and pressure change (hydrostatic, osmotic). Hepatic fibrosis (HF) is a consequence of all chronic liver diseases and progresses towards cirrhosis and finally cancer. Noninvasive diagnosis and staging is important clinical issue for hepatic fibrosis which is reversible. Elastrography is clinically acceptable for the prediction of liver fibrosis ($F2) and confounders of stiffness measurement (intercostal approach to right lobe (S7/8), 1-3 cm below the liver capsule, biologic confounders can change stiffness values, fasting at least 2 hours, breathhold at expiration). Elastography is one of important noninvasive methods to quantify HF more sensitively and objectively. USE is the first line examination for the assessment of HF. MRE is the second line examination, especially in cirrhosis. To avoid confounders of liver stiffness, comprehensive other imaging exams are needed. T12-14-IN05 QIBA Ultrasound Shear Wave Speed Biomarker Update Shigao Chen, Manish Dhyani, Brian Garra, Timothy Hall, Mark Palmeri The Quantitative Imaging Biomarkers Alliance (QIBA) was organized by RSNA to improve the value and practicality of quantitative imaging biomarkers by reducing variability across devices, patients, and time. The QIBA Ultrasound Shear Wave Speed (SWS) Biomarker Committee was formed in 2012 by researchers, healthcare professionals, regulatory agencies, and industry stakeholders to advance SWS as a quantitative biomarker for liver fibrosis staging. This presentation will give a brief introduction of the general QIBA concept and procedure, the work that the Ultrasound SWS Biomarker Committee has performed, and the current status of the SWS ‘‘Profile’’, which is a detailed

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document describing what quantitative results (e.g., bias and precision of SWS measurements) can be achieved by following the imaging protocol included in the Profile. T12-14-IN06 Ultrasound Statistical Parametric Imaging in the Assessment of Fatty Liver Po-Hsiang Tsui Department of Medical Imaging and Radiological Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan, Institute for Radiological Research, Chang Gung University and Chang Gung Memorial Hospital at Linkou, Taoyuan, Taiwan, Department of Medical Imaging and Intervention, Chang Gung Memorial Hospital at Linkou, Taoyuan, Taiwan Hepatitis steatosis may progress to nonalcoholic steatohepatitis, fibrosis, cirrhosis, and hepatocellular carcinoma. Nonalcoholic fatty liver disease (NAFLD) is the type of hepatic steatosis that most commonly leads to chronic liver disease. NAFLD is also related to metabolic risk factors. How to characterize fatty liver is attracting growing medical and health research interest. Notably, the speckle pattern is formed by ultrasound backscattered echoes, which are typically treated as random signals. Thus, analyzing the statistical distribution of the echo amplitude (i.e., the envelope signal) may provide useful clues associated with fatty liver diseases. Many investigators have began to study the relationship between the probability property of inverse scattering and the characteristics of tissue. Commonly used statistical models include the Rayleigh distribution, Rician distribution, K distribution, homodyned K distribution, Nakagami distribution, and compounding Nakagami distribution. One requisite of using statistical models to fit echo amplitude distributions is that the ultrasound envelope data must conform to the used distribution. To overcome the limitations mentioned above, we need to set a new direction for constructing the images of ultrasound parameters outside the statistical model ultrasonic method. Recall that Shannon established information theory and defined entropy as a measure of information uncertainty. Hughes pioneered using Shannon entropy for analyzing ultrasound signals, indicating that entropy is able to quantitatively describe changes in the microstructures of scattering media. Recently, we also developed the small-window entropy image of ultrasound by using a simple model of histograms and defined the weighted entropy to provide greater sensitivity in diagnosing the changes of the scattering microstructures of tissues. The results showed that fatty infiltration increases the uncertainty of backscattered signals from livers. Ultrasound entropy imaging has potential for the routine examination of fatty liver disease. T12-14-IN07 ARFI in the Assessment of NAFLD Severity Jee-Fu Huang, MD, PhD Hepatitis Centre, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan, Graduate Institute of Clinical Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan Non-alcoholic liver disease (NAFLD) has recently been recognized as the most prevalent liver disease worldwide. The features are in a similar trend found in Asia-Pacific. Non-alcoholic steatohepatitis (NASH) was defined by histopathologic evidence as an extreme form of NAFLD. The risk of development of fibrosis, cirrhosis and liver-related deaths in NASH patients cannot be overlooked. NASH patients had higher overall mortality compared with controls, and most deaths were due to cardiovascular events. In addition, Asian people are more prone to metabolic syndrome (MetS), DM and NAFLD than other races. Accurate determination of the presence and extent of liver fibrosis is essential for prognosis and for treatment planning in NAFLD patients. Exploration of non-invasive methods to evaluate disease severity is