Ultrasound evaluation of liver fibrosis: preliminary experience with acoustic structure quantification (ASQ) software

Exosomes and ultrasound: The future of theranostic applications

Biomaterials and pertaining formulations have been very successful in various diagnostic and therapeutic applications because of its ability to overcome pharmacological limitations. Some of them have gained significant focus in the recent decade for their theranostic properties. Exosomes can be grouped as biomaterials, since they consist of various biological micro/macromolecules and possess all the properties of a stable biomaterial with size in nano range. Significant research has gone into isolation and exploitation of exosomes as potential theranostic agent. However, the limitations in terms of yield, efficacy, and target specificity are continuously being addressed. On the other hand, several nano/microformulations are responsive to physical or chemical alterations and were successfully stimulated by tweaking the physical characteristics of the surrounding environment they are in. Some of them are termed as photodynamic, sonodynamic or thermodynamic therapeutic systems. In this regard, ultrasound and acoustic systems were extensively studied for its ability towards altering the properties of the systems to which they were applied on. In this review, we have detailed about the diagnostic and therapeutic applications of exosomes and ultrasound separately, consisting of their conventional applications, drawbacks, and developments for addressing the challenges. The information were categorized into various sections that provide complete overview of the isolation strategies and theranostic applications of exosomes in various diseases. Then the ultrasound-based disease diagnosis and therapy were elaborated, with special interest towards the use of ultrasound in enhancing the efficacy of nanomedicines and nanodrug delivery systems, Finally, we discussed about the ability of ultrasound in enhancing the diagnostic and therapeutic properties of exosomes, which could be the future of theranostics.

Assessment of the frequency dependence of acoustic properties on material, composition, and scatterer size of the medium

PURPOSE

The aim of this study was to elucidate the frequency dependence of the speed of sound (SoS) and attenuation coefficients in phantoms with controlled attenuation properties (scatterer density, scatterer size, absorption control material) and rat livers.

METHODS

The frequency dependence of SoS and attenuation coefficients were evaluated with ultrasound (1-15 MHz) by observing multiple phantoms with different scatterer sizes, densities, and presence or absence of evaporated milk as absorbing media. Normal and fatty model rat livers were examined with the same protocol.

RESULTS

The phantom results revealed that the scatterer density and SoS of the base media were the dominant factors causing the changes in SoS. Frequency dependence was not observed in SoS. Assessment of the attenuation coefficient showed that the frequency dependence was mainly affected by absorption attenuation when the scatterer was as small as a hepatocyte (i.e. ≤ 10 µm). Scattering attenuation was also observed to affect frequency dependence when the scatterer was as large as lipid droplets (i.e. ≤ 40 µm).

CONCLUSION

Assuming a consistent size of the main scatterers in the evaluation medium, the frequency dependence of the SoS and attenuation coefficients may provide insight into the scatterer density and the contribution of absorption and scattering attenuation. Further studies in the higher frequency band (up to about 50 MHz) are expected to advance the clinical application of high-frequency ultrasound.

The severity of portal hypertension by a non-invasive assessment: acoustic structure quantification analysis of liver parenchyma

Background

Acoustic structure quantification (ASQ) has been applied to evaluate liver histologic changes by analyzing the speckle pattern seen on B-mode ultrasound. We aimed to assess the severity of portal hypertension (PHT) through hepatic ultrasonography.

Methods

Sixty patients diagnosed with PHT and underwent surgical treatment with portosystemic shunts were enrolled. Portal pressure (PP) was measured intraoperatively. Patients were divided into subgroups according to the severity of gastroesophageal varices and Child–Pugh class. Three difference ratio (C_m²) values on ASQ histogram mode were analyzed for their relationships with PP, degree of gastroesophageal varices and Child–Pugh liver function. Thirty healthy volunteers matched with the patients for gender and age were enrolled as controls. Comparisons among groups and correlation of the parameters with PP were analyzed. Area under the receive operating characteristic curve was used to evaluate the predicting value of ASQ parameters.

Results

In the patients, the ASQ parameters peak C_m² (C_m²_max), mean C_m² (C_m²_mean) and the highest occurred C_m² value of the obtained red curve (R_maxC_m²) were all greatly increased (P < 0.0001, P < 0.0001, P = 0.027). Multiple comparisons indicated that, regardless of Child–Pugh class and degree of gastroesophageal varices, the patients had significantly increased C_m²_max and C_m²_mean compared with the controls (all P < 0.0001). No differences among subgroups were observed. C_m²_max was significantly statistically correlated with PP (r = 0.3505, P < 0.01), degree of varices (r = 0.4998, P < 0.0001). Youden’s index for C_m²_max with a cut-off value of 140.3 for predicting the presence of PHT, gastroesophageal varices and liver function equal to or worse than Child–Pugh class B were 0.8, 0.91 and 0.84, respectively.

Conclusions

ASQ analysis of ultrasonographic images may have a role in the evaluation of the severity of PHT by detecting liver histologic changes in the speckle pattern caused by cirrhosis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12880-022-00817-2.

Quantitative Evaluation of Hepatic Steatosis Using Advanced Imaging Techniques: Focusing on New Quantitative Ultrasound Techniques

Nonalcoholic fatty liver disease, characterized by excessive accumulation of fat in the liver, is the most common chronic liver disease worldwide. The current standard for the detection of hepatic steatosis is liver biopsy; however, it is limited by invasiveness and sampling errors. Accordingly, MR spectroscopy and proton density fat fraction obtained with MRI have been accepted as non-invasive modalities for quantifying hepatic steatosis. Recently, various quantitative ultrasonography techniques have been developed and validated for the quantification of hepatic steatosis. These techniques measure various acoustic parameters, including attenuation coefficient, backscatter coefficient and speckle statistics, speed of sound, and shear wave elastography metrics. In this article, we introduce several representative quantitative ultrasonography techniques and their diagnostic value for the detection of hepatic steatosis.

Noninvasive, quantitative evaluation of hepatic steatosis of donor livers by reference frequency method: A preliminary study

PURPOSE

Evaluating degree of hepatic steatosis is of great value for prognosis of liver transplantation. There is an urgent need for a non-invasive method to assess hepatic steatosis grade of donor livers. Purpose of our study was to evaluate diagnostic accuracy of attenuation coefficient estimation (ACE) by reference frequency method (RFM) in detecting hepatic steatosis of donor livers.

METHOD

We retrospectively enrolled 62 potential liver donors which underwent ACE by RFM ex-vivo, in-vivo or both. We acquired raw data of B-mode images of liver parenchyma and offline-processes for attenuation estimation. Finally, we calculated and compared diagnostic performance of ACEs for steatosis grade detection and used histological results as the gold standard.

RESULTS

ACEs with none, mild and moderate hepatic steatosis were 0.57, 0.73 and 0.80 dB/cm/MHz in potential donor livers. The cutoff value to diagnose mild hepatic steatosis was 0.63 dB/cm/MHz and 0.77 dB/cm/MHz for moderate hepatic steatosis, and values for the area under the receiver operating characteristic curve for diagnosis of mild and moderate hepatic steatosis were 0.92 and 0.90, respectively.

CONCLUSIONS

According to our results, ACE by RFM is an accurate non-invasive method in detecting hepatic steatosis, which may be of great help for clinical evaluation of donor livers before liver transplantation.

Shear wave elastography and transient elastography in HCV patients after direct-acting antivirals

PURPOSE

To compare the ultrasound (US) and pulse shear wave elastography (pSWE, Elast PQ^®) methods with transient elastography (TE), clinical scores and laboratory tests, during the follow-up of HCV patients receiving direct-acting antiviral drugs (DAA).

METHODS

Our prospective study from June 2016 to December 2017 included 22 consecutively enrolled HCV-positive patients (59.7 ± 12.3 years, 11 male) which were subjected to antiviral therapy. All patients underwent B-mode ultrasound, color-Doppler, pSWE and TE five times: before therapy (T0), at the end of therapy (post-Tx), and at 12, 24, 48 weeks post-therapy. The liver stiffness (LS) values obtained with pSWE and TE and the data coming from US assessment and clinical evaluation were compared.

RESULTS

We obtained a statistically significant reduction of LS values (kPa) measured by pSWE, between T0 (14.3 ± 9.3), post-Tx (11.8 ± 10.5), 12 weeks (7.5 ± 3.3), 24 weeks (8 ± 3.8) and 48 weeks (8.5 ± 4.6) (p = 0.02). The reduction of kPa measured by TE was not significant between T0 (14.7 ± 9.3), post-Tx (12 ± 9.5), 12 weeks (11.6 ± 7.7), 24 weeks (10.3 ± 6) and 48 weeks (10.8 ± 7.5) (p > 0.05). Multivariate baseline analysis showed significant independent association among measurement of TE stiffness with cirrhosis, type of vein hepatic flow and showed significant independent association between delta-pSWE measurement (difference between stiffness measurements at the baseline and 12 months after treatment) with staging of fibrosis (p = 0.006) and sustained virologic response after 12 weeks of treatment (SVR12, p = 0.017).

CONCLUSION

The pSWE method has shown better ability than TE to identify a reduction in LS. Therefore, pSWE allow to evaluate stiffness reduction in HCV patient during DAA treatment follow-up, which is related to SVR12.

The clinical utility of accurate NAFLD ultrasound grading: Results from a community-based, prospective cohort study

OBJECTIVES

Despite its widespread use there is no consensus on ultrasound criteria to diagnose fatty liver.

METHOD

In an ongoing, cohort-study, participants were initially screened in 2007 and reassessed in 2014 by interview, anthropometric measurements, liver ultrasonography, and blood tests. We evaluated utility of increased hepatic echogenicity alone (intermediate) compared to using additional criteria which included signal attenuation and/or vascular blunting along with increase of hepatic echogenicity (moderate-severe), to diagnose fatty liver in NAFLD. We made a comparison of the two radiologically defined groups, in order to choose a classification method for NAFLD, which may better predict baseline adverse metabolic traits (MT), and adverse metabolic and cardiovascular events (CVE) after 7-year of follow-up.

RESULTS

Of 2985 recruited in 2007, 940 (31.5 %) had moderate-severe NAFLD, 595 (19.9 %) intermediate NAFLD, and 957 (32.1 %) were controls (no fatty liver). 2148 (71.9 %) attended follow-up in 2014; they included 708 who had moderate-severe NAFLD, 446 intermediate NAFLD and 674 controls, at baseline (in 2007). At baseline, adverse anthropometric indices and MTs were significantly higher in both moderate-severe NAFLD and intermediate NAFLD compared to controls, except for low HDL. They were commoner in moderate-severe NAFLD than in intermediate NAFLD. After seven years, the odds of developing new-onset metabolic traits and CVEs were significantly higher compared to controls only in moderate-severe NAFLD.

CONCLUSIONS

Only moderate-severe NAFLD predicted risk of incident adverse MTs and CVEs. However, both moderate-severe and intermediate NAFLD were associated with higher prevalence of adverse anthropometric and metabolic traits, thereby identifying individuals who need medical intervention even among those with milder degrees of fatty liver. We therefore recommend using increased hepatic echogenicity, and not only the more stringent criteria (which include signal attenuation and/or vascular blunting), for the diagnosis of fatty liver in individuals with NAFLD.

Ultrasound Detection of Liver Fibrosis in Individuals with Hepatic Steatosis Using the Homodyned K Distribution

Acoustic structure quantification (ASQ) based on the analysis of ultrasound backscattered statistics has been reported to detect liver fibrosis without significant hepatic steatosis. This study proposed using ultrasound parametric imaging based on the parameter α of the homodyned K (HK) distribution for staging liver fibrosis in patients with significant hepatic steatosis. Raw ultrasound image data were acquired from patients (n = 237) to construct B-mode and HK α parametric images, which were compared with the focal disturbance (FD) ratio obtained from ASQ on the basis of histologic evidence (METAVIR fibrosis score and hepatic steatosis severity). The data were divided into group I (n = 173; normal to mild hepatic steatosis) and group II (n = 64; with moderate to severe hepatic steatosis) for statistical analysis through one-way analysis of variance and receiver operating characteristic (ROC) curve analysis. The results showed that the HK α parameter monotonically decreased as the liver fibrosis stage increased (p < .05); concurrently, the FD ratio increased (p < .05). For group I, the areas under the ROC (AUROCs) obtained using the FD ratio and the α parameter (AUROC_FD and AUROC_α) were, respectively, 0.56 and 0.55, 0.68 and 0.68, 0.64 and 0.64 and 0.62 and 0.62 for diagnosing liver fibrosis ≥F1, ≥F2, ≥F3 and ≥F4. The values of AUROC_FD and AUROC_α for group II were, respectively, 0.88 and 0.91, 0.81 and 0.81, 0.77 and 0.76 and 0.78 and 0.73 for diagnosing liver fibrosis ≥F1, ≥F2, ≥F3 and ≥F4. As opposed to previous studies, ASQ was found to fail in characterizing liver fibrosis in group I; however, it was workable for identifying liver fibrosis in patients with significant hepatic steatosis (group II). Compared with ASQ, HK imaging provided improved diagnostic performance in the early detection of liver fibrosis coexisting with moderate to severe hepatic steatosis. Ultrasound HK imaging is recommended as a strategy to evaluate early fibrosis risk in patients with significant hepatic steatosis.

Basic concept and clinical applications of quantitative ultrasound (QUS) technologies

In the field of clinical ultrasound, the full digitalization of diagnostic equipment in the 2000s enabled the technological development of quantitative ultrasound (QUS), followed by multiple diagnostic technologies that have been put into practical use in recent years. In QUS, tissue characteristics are quantified and parameters are calculated by analyzing the radiofrequency (RF) echo signals returning to the transducer. However, the physical properties (and pathological level structure) of the biological tissues responsible for the imaging features and QUS parameters have not been sufficiently verified as there are various conditions for observing living tissue with ultrasound and inevitable discrepancies between theoretical and actual measurements. A major issue of QUS in clinical application is that the evaluation results depend on the acquisition conditions of the RF echo signal as the source of the image information, and also vary according to the model of the diagnostic device. In this paper, typical examples of QUS techniques for evaluating attenuation, speed of sound, amplitude envelope characteristics, and backscatter coefficient in living tissues are introduced. Exemplary basic research and clinical applications related to these technologies, and initiatives currently being undertaken to establish the QUS method as a true tissue characterization technology, are also discussed.

High resolution ultrasound imaging for repeated measure of wound tissue morphometry, biomechanics and hemodynamics under fetal, adult and diabetic conditions

Non-invasive, repeated interrogation of the same wound is necessary to understand the tissue repair continuum. In this work, we sought to test the significance of non-invasive high-frequency high-resolution ultrasound technology for such interrogation. High-frequency high-resolution ultrasound imaging was employed to investigate wound healing under fetal and adult conditions. Quantitative tissue cellularity and elastic strain was obtained for visualization of unresolved inflammation using Vevo strain software. Hemodynamic properties of the blood flow in the artery supplying the wound-site were studied using color Doppler flow imaging. Non-invasive monitoring of fetal and adult wound healing provided unprecedented biomechanical and functional insight. Fetal wounds showed highly accelerated closure with transient perturbation of wound tissue cellularity. Fetal hemodynamics was unique in that sharp fall in arterial pulse pressure (APP) which was rapidly restored within 48h post-wounding. In adults, APP transiently increased post-wounding before returning to the pre-wounding levels by d10 post-wounding. The pattern of change in the elasticity of wound-edge tissue of diabetics was strikingly different. Severe strain acquired during the early inflammatory phase persisted with a slower recovery of elasticity compared to that of the non-diabetic group. Wound bed of adult diabetic mice (db/db) showed persistent hypercellularity compared to littermate controls (db/+) indicative of prolonged inflammation. Normal skin strain of db/+ and db/db were asynchronous. In db/db, severe strain acquired during the early inflammatory phase persisted with a slower recovery of elasticity compared to that of non-diabetics. This study showcases a versatile clinically relevant imaging platform suitable for real-time analyses of functional wound healing.

Ultrasound Backscatter Envelope Statistics Parametric Imaging for Liver Fibrosis Characterization: A Review

Early detection and diagnosis of liver fibrosis is of critical importance. Currently the gold standard for diagnosing liver fibrosis is biopsy. However, liver biopsy is invasive and associated with sampling errors and can lead to complications such as bleeding. Therefore, developing noninvasive imaging techniques for assessing liver fibrosis is of clinical value. Ultrasound has become the first-line tool for the management of chronic liver diseases. However, the commonly used B-mode ultrasound is qualitative and can cause interobserver or intraobserver difference. Ultrasound backscatter envelope statistics parametric imaging is an important group of quantitative ultrasound techniques that have been applied to characterizing different kinds of tissue. However, a state-of-the-art review of ultrasound backscatter envelope statistics parametric imaging for liver fibrosis characterization has not been conducted. In this paper, we focused on the development of ultrasound backscatter envelope statistics parametric imaging techniques for assessing liver fibrosis from 1998 to September 2019. We classified these techniques into six categories: constant false alarm rate, fiber structure extraction technique, acoustic structure quantification, quantile-quantile probability plot, the multi-Rayleigh model, and the Nakagami model. We presented the theoretical background and algorithms for liver fibrosis assessment by ultrasound backscatter envelope statistics parametric imaging. Then, the specific applications of ultrasound backscatter envelope statistics parametric imaging techniques to liver fibrosis evaluation were reviewed and analyzed. Finally, the pros and cons of each technique were discussed, and the future development was suggested.

Evaluation of hepatic fibrosis by ultrasonic acoustic structure quantification

To evaluate the diagnostic accuracy of ultrasonic acoustic structure quantification (ASQ) for grading hepatic fibrosis/cirrhosis by comparing ultrasonographic features of regions of interest on ASQ images with the pathological characteristics of stage F0-F4 hepatic fibrosis cases.We retrospectively analyzed the medical records of 97 patients with chronic hepatitis who underwent ASQ evaluation at the Ultrasound Room of Dongfang Hepatobiliary Surgery Hospital (Shanghai, China) between July 2012 and October 2013. Regions of interest on stored ASQ images were analyzed to obtain cm values on modes, averages, and standard deviations. Correlation analysis, principal component analysis (PCA), and multivariate analysis of variance (MANOVA) of the mean cm values with hepatic fibrosis staging were performed. A receiver operating characteristic (ROC) curve was used to assess the diagnostic accuracy of ASQ.The mean cm of ASQ correlated with the pathological stage of hepatic fibrosis, with the best correlation coefficient (r = 0.81) in the right lobe below rib 2. The best cm average 1 and 2 values, which differed significantly among different hepatic fibrosis/cirrhosis stages, were also found in this area. The maximal area under the ROC curve (0.969) was for cmaverage 1 for the F0 versus F1 to F4 group, with a low criterion (110), while the maximal criterion (145) was for cm average 2 for the F0-F3 versus F4 group, with a relatively small AUC (0.882).With objective and accurate results, ASQ analysis is a promising non-invasive method for grading hepatic fibrosis, although this should be verified in further studies.

Considerations of Ultrasound Scanning Approaches in Non-alcoholic Fatty Liver Disease Assessment through Acoustic Structure Quantification

Non-alcoholic fatty liver disease (NAFLD) is a risk factor for hepatic fibrosis and cirrhosis. Acoustic structure quantification (ASQ), based on statistical analysis of ultrasound echoes, is an emerging technique for hepatic steatosis diagnosis. A standardized measurement protocol for ASQ analysis was suggested previously; however, an optimal ultrasound scanning approach has not been concluded thus far. In this study, the suitability of scanning approaches for the ASQ-based evaluation of hepatic steatosis was investigated. Hepatic fat fractions (HFFs; liver segments VIII, III and VI) of 70 living liver donors were assessed with magnetic resonance spectroscopy. A clinical ultrasound machine equipped with a 3-MHz convex transducer was used to scan each participant using the intercostal, epigastric and subcostal planes to acquire raw data for estimating two ASQ parameters (C_m² and focal disturbance [FD] ratio) of segments VIII, III and VI, respectively. The parameters were plotted as functions of the HFF for calculating the values of the correlation coefficient (r) and probability value (p). The diagnostic performance of the parameters in discriminating between the normal and steatotic (≥5 and ≥10%) groups was also compared using receiver operating characteristic (ROC) curves. The C_m² and FD ratio values measured using the epigastric and subcostal planes did not correlate with the severity of hepatic steatosis. However, intercostal imaging exhibited a higher correlation between the ASQ parameters and HFF (r = -0.64, p < 0.001). The diagnostic performance of C_m² and FD ratio in detecting hepatic steatosis using intercostal imaging was also satisfactory (areas under ROC curves >0.8). Intercostal imaging is an appropriate scanning approach for ASQ analysis of the liver.

Comparison of Acoustic Structure Quantification, Transient Elastography (FibroScan) and Histology in Patients with Chronic Hepatitis B and without Moderate to Severe Hepatic Steatosis

The purpose of this study was to compare acoustic structure quantification (ASQ) with transient elastography for staging liver fibrosis. One hundred eighty-two patients with chronic hepatitis B and without moderate to severe hepatic steatosis scheduled for liver biopsy underwent ASQ and transient elastography examinations. All ASQ parameters, including total mode, total average, red mode, red average, red standard deviation, blue mode, blue average, blue standard deviation and focal disturbance (FD) ratio and liver stiffness obtained via transient elastography were found to correlate with fibrosis stage (Spearman's r = 0.783, 0.791, 0.750, 0.771, 0.544, 0.718, 0.691, 0.439, 0.815 and 0.814, respectively; all p values < 0.001). Among the ASQ parameters, the FD ratio had the highest correlation with the stage of fibrosis. The areas under the receiver operating characteristic curves (AUCs) of FD ratio and liver stiffness were 0.911 and 0.906 for F ≥ F1, 0.918 and 0.882 for F ≥ F2, 0.911 and 0.914 for F ≥ F3 and 0.926 and 0.978 for F = F4, respectively. There was no significant difference in AUCs between FD ratio and liver stiffness in predicting different stages of fibrosis (p = 0.062-0.912). ASQ is a promising technique for assessing liver fibrosis in the absence of moderate to severe hepatic steatosis.

Ultrasound of Diffuse Liver Disease Including Elastography

Diffuse liver disease is a substantial world-wide problem. With the combination of conventional ultrasound of the abdomen and elastography-appropriate staging of the patient can be assessed. This information allows for the detection of fibrosis as well as prognosis, surveillance, and prioritization for treatment. With the potential for reversibility with appropriate treatment, accurate assessment for the stage of chronic liver disease is critical.

Liver elastography malignancy prediction score for noninvasive characterization of focal liver lesions

BACKGROUND & AIMS

To analyse elastographic characteristics of focal liver lesions (FLL)s and diagnostic performance of real-time two-dimensional shear-wave elastography (RT-2D-SWE) in order to differentiate benign and malignant FLLs.

METHODS

Consecutive patients diagnosed with FLL by abdominal ultrasound (US) underwent RT-2D-SWE of FLL and non-infiltrated liver by intercostal approach over the right liver lobe. The nature of FLL was determined by diagnostic work-up, including at least one contrast-enhanced imaging modality (MDCT/MRI), check-up of target organs when metastatic disease was suspected and FLL biopsy in inconclusive cases.

RESULTS

We analysed 196 patients (median age 60 [range 50-68], 50.5% males) with 259 FLLs (57 hepatocellular carcinomas, 17 cholangiocarcinomas, 94 metastases, 71 haemangiomas, 20 focal nodular hyperplasia) of which 70 (27%) were in cirrhotic liver. Malignant lesions were stiffer (P < .001) with higher variability in intralesional stiffness (P = .001). The best performing cut-off of lesion stiffness was 22.3 kPa (sensitivity 83%; specificity 86%; positive predictive value [PPV] 91.5%; negative predictive value [NPV] 73%) for malignancy. Lesion stiffness <14 kPa had NPV of 96%, while values >32.5 kPa had PPV of 96% for malignancy. Lesion stiffness, lesion/liver stiffness ratio and lesion stiffness variability significantly predicted malignancy in stepwise logistic regression (P < .05), and were used to construct a new Liver Elastography Malignancy Prediction (LEMP) score with accuracy of 96.1% in validation cohort (online calculator available at http://bit.do/lemps).

CONCLUSION

The comprehensive approach demonstrated in this study enables correct differentiation of benign and malignant FLL in 96% of patients by using RT-2D-SWE.

Acoustic Structure Quantification Versus Point Shear Wave Speed Measurement for the Assessment of Liver Fibrosis in Viral Hepatitis B

This study was conducted to evaluate the value of acoustic structure quantification (ASQ) technology versus that of point shear wave speed measurement (PSWSM) imaging technology for the assessment of liver fibrosis stage. A total of 104 patients with chronic hepatitis B (CHB) and 30 healthy control patients underwent ASQ and PSWSM examinations. Seven quantitative parameters were obtained from ASQ, and a principal component analysis was used to establish the integrative indicators. A quantitative parameter, known as the shear wave speed (SWS, m/s), was obtained from the PSWSM. The METAVIR scores for the assessment of pathologic liver fibrosis were used as a benchmark. Liver fibrosis stages exhibited a good correlation with the integrative indicators and SWS (r = 0.682, p <0.001; r = 0.651, p <0.001). The areas under the receiver operating characteristic curves for ASQ and PSWSM were 0.705 and 0.854 for mild liver fibrosis (F ≥ 1, p = 0.045), 0.813 and 0.743 for significant liver fibrosis (F ≥ 2, p = 0.115), 0.839 and 0.857 for severe liver fibrosis (F ≥ 3, p = 0.417) and 0.874 and 0.971 for liver cirrhosis (F = 4, p = 0.016), respectively. In conclusion, both ASQ and PSWSM were promising ultrasonic methods for assessing liver fibrosis in patients with CHB; however, PSWSM was more valuable for identifying mild liver fibrosis (F ≥ 1) and cirrhosis (F = 4) than ASQ, and the combination of PSWSM and ASQ improved the accuracy of diagnosing severe liver fibrosis (F ≥ 3).

Automated classification of focal breast lesions according to S-detect: validation and role as a clinical and teaching tool

PURPOSE

To assess the diagnostic performance and the potential as a teaching tool of S-detect in the assessment of focal breast lesions.

METHODS

61 patients (age 21-84 years) with benign breast lesions in follow-up or candidate to pathological sampling or with suspicious lesions candidate to biopsy were enrolled. The study was based on a prospective and on a retrospective phase. In the prospective phase, after completion of baseline US by an experienced breast radiologist and S-detect assessment, 5 operators with different experience and dedication to breast radiology performed elastographic exams. In the retrospective phase, the 5 operators performed a retrospective assessment and categorized lesions with BI-RADS 2013 lexicon. Integration of S-detect to in-training operators evaluations was performed by giving priority to S-detect analysis in case of disagreement. 2 × 2 contingency tables and ROC analysis were used to assess the diagnostic performances; inter-rater agreement was measured with Cohen's k; Bonferroni's test was used to compare performances. A significance threshold of p = 0.05 was adopted.

RESULTS

All operators showed sensitivity > 90% and varying specificity (50-75%); S-detect showed sensitivity > 90 and 70.8% specificity, with inter-rater agreement ranging from moderate to good. Lower specificities were improved by the addition of S-detect. The addition of elastography did not lead to any improvement of the diagnostic performance.

CONCLUSIONS

S-detect is a feasible tool for the characterization of breast lesions; it has a potential as a teaching tool for the less experienced operators.

Influencing Factors of 2D Shear Wave Elastography of the Muscle - An Ex Vivo Animal Study

OBJECTIVE

To evaluate measurement confounders on 2D shear wave elastography (2D-SWE) elastography of muscle.

MATERIALS AND METHODS

Ex vivo , porcine muscle was examined with a GE LOGIQ E9 ultrasound machine with a 9 L linear (9 MHz) and C1-6 convex probe (operating at 2.5 or 6 MHz). The influence of different confounders on mean shear wave velocity (SWVmean) was analyzed: probes, pressure applied by probe, muscle orientation, together with the impact of different machine settings such as frequency, placement depth and size of region of interest (ROI). The mean of twelve repeated SWVmean measurements (m/s) and coefficient of variation (CV; standard deviation/mean in %) were assessed for each test configuration.

RESULTS

Reproducibility (CV) and maximum possible tissue depth of the linear probe were inferior to the convex probe. With the linear probe, there was a linear decrease of SWVmean with placement depth from 4.56 m/s to 1.81 m/s. A significant increase of SWVmean (p<0.001) was observed for larger ROI widths (range 3.96 m/s to 6.8 m/s). A change in the machine operation mode ('penetration' instead of 'general') led to a significant increase of SWVmean (p=0.04). SWVmean in the longitudinal direction of muscle was significantly higher than in cross section (p<0.001) (e. g. 4.56 m/s versus 3.42 m/s). An increase of linear probe pressure significantly increased muscle SWVmean from 5.29 m/s to 7.21 m/s (p<0.001).

CONCLUSIONS

2D-SWE of muscle is influenced by a wealth of parameters. Therefore, standardization of measurement is advisable before application in clinical research studies and routine patient assessment.

CEUS in the differential diagnosis between biliary sludge, benign lesions and malignant lesions

PURPOSE

Conventional grayscale ultrasound (US) is accurate in the diagnosis of gallbladder disease (GD), but in some cases, it is not decisive. Contrast-enhanced ultrasound (CEUS) improves the diagnostic accuracy of US. The primary objective of this study is to assess the reliability of CEUS in the diagnosis of sludge; the secondary objective is to assess the ability of CEUS to diagnose cancer.

METHODS

We retrospectively reviewed the US of 4137 patients positive for GD. In 43/4137 (1.04%), the use of could not discriminate between sludge and neoplasms. Then, we evaluated CEUS in only 39 of these patients, and in 4/43 (9%) cases it was not performable. After CEUS, the absence of enhancement was considered diagnostic for sludge, while contrast washout within 60 s diagnosed malignant lesions.

RESULTS

Among the 39 patients, 16 had biliary sludge and 23 had lesions of the gallbladder wall; 9 of these were carcinomas and 14 were benign tumors. The absence of enhancement was present in 16/16 patients with sludge and in 0/23 patients with lesions of the gallbladder (sensitivity and specificity 100%). Washout was within 60 s in 9/9 gallbladder carcinomas and 2/14 benign lesions (sensitivity 100%; specificity 85%).

CONCLUSIONS

US is confirmed to be accurate in the diagnosis of GD. In doubtful cases, CEUS is very accurate in biliary sludge diagnosis. An intralesional washout at 60 s is a pattern of malignancy that can orient towards a correct diagnosis, but it is limited by the presence of false positive results, especially for smaller lesions.

Intrasynovial spindle cell lipoma of the deep flexor of the middle finger causing intermittent carpal tunnel syndrome-case report and review of the literature

Carpal tunnel syndrome (CTS) represents the most common entrapment neuropathy of the upper extremity. Intermittent CTS has been reported in the surgical literature and usually, related to masses associated to flexor tendons. We describe a patient with an intrasynovial lipoma involving the deep flexor of the middle finger causing intermittent CTS and snapping on flexion-extension.

Effect of ultrasound frequency on the Nakagami statistics of human liver tissues

The analysis of the backscattered statistics using the Nakagami parameter is an emerging ultrasound technique for assessing hepatic steatosis and fibrosis. Previous studies indicated that the echo amplitude distribution of a normal liver follows the Rayleigh distribution (the Nakagami parameter m is close to 1). However, using different frequencies may change the backscattered statistics of normal livers. This study explored the frequency dependence of the backscattered statistics in human livers and then discussed the sources of ultrasound scattering in the liver. A total of 30 healthy participants were enrolled to undergo a standard care ultrasound examination on the liver, which is a natural model containing diffuse and coherent scatterers. The liver of each volunteer was scanned from the right intercostal view to obtain image raw data at different central frequencies ranging from 2 to 3.5 MHz. Phantoms with diffuse scatterers only were also made to perform ultrasound scanning using the same protocol for comparisons with clinical data. The Nakagami parameter-frequency correlation was evaluated using Pearson correlation analysis. The median and interquartile range of the Nakagami parameter obtained from livers was 1.00 (0.98-1.05) for 2 MHz, 0.93 (0.89-0.98) for 2.3 MHz, 0.87 (0.84-0.92) for 2.5 MHz, 0.82 (0.77-0.88) for 3.3 MHz, and 0.81 (0.76-0.88) for 3.5 MHz. The Nakagami parameter decreased with the increasing central frequency (r = -0.67, p < 0.0001). However, the effect of ultrasound frequency on the statistical distribution of the backscattered envelopes was not found in the phantom results (r = -0.147, p = 0.0727). The current results demonstrated that the backscattered statistics of normal livers is frequency-dependent. Moreover, the coherent scatterers may be the primary factor to dominate the frequency dependence of the backscattered statistics in a liver.

Acoustic Impedance Analysis with High-Frequency Ultrasound for Identification of Fatty Acid Species in the Liver

Acoustic properties of free fatty acids present in the liver were studied as a possible basis for non-invasive ultrasonic diagnosis of non-alcoholic steatohepatitis. Acoustic impedance was measured for the following types of tissue samples: Four pathologic types of mouse liver, five kinds of FFAs in solvent and five kinds of FFAs in cultured Huh-7 cells. A transducer with an 80-MHz center frequency was incorporated into a scanning acoustic microscopy system. Acoustic impedance was calculated from the amplitude of the signal reflected from the specimen surface. The Kruskal-Wallis test revealed statistically significant differences (p < 0.01) in acoustic impedance not only among pathologic types, but also among the FFAs in solvent and in cultured Huh-7 cells. These results suggest that each of the FFAs, especially palmitate, oleate and palmitoleate acid, can be distinguished from each other, regardless of whether they were in solution or absorbed by cells.

Acoustic structure quantification by using ultrasound Nakagami imaging for assessing liver fibrosis

Acoustic structure quantification (ASQ) is a recently developed technique widely used for detecting liver fibrosis. Ultrasound Nakagami parametric imaging based on the Nakagami distribution has been widely used to model echo amplitude distribution for tissue characterization. We explored the feasibility of using ultrasound Nakagami imaging as a model-based ASQ technique for assessing liver fibrosis. Standard ultrasound examinations were performed on 19 healthy volunteers and 91 patients with chronic hepatitis B and C (n = 110). Liver biopsy and ultrasound Nakagami imaging analysis were conducted to compare the METAVIR score and Nakagami parameter. The diagnostic value of ultrasound Nakagami imaging was evaluated using receiver operating characteristic (ROC) curves. The Nakagami parameter obtained through ultrasound Nakagami imaging decreased with an increase in the METAVIR score (p < 0.0001), representing an increase in the extent of pre-Rayleigh statistics for echo amplitude distribution. The area under the ROC curve (AUROC) was 0.88 for the diagnosis of any degree of fibrosis (≥F1), whereas it was 0.84, 0.69, and 0.67 for ≥F2, ≥F3, and ≥F4, respectively. Ultrasound Nakagami imaging is a model-based ASQ technique that can be beneficial for the clinical diagnosis of early liver fibrosis.

Ultrasound window-modulated compounding Nakagami imaging: Resolution improvement and computational acceleration for liver characterization

Ultrasound Nakagami imaging is an attractive method for visualizing changes in envelope statistics. Window-modulated compounding (WMC) Nakagami imaging was reported to improve image smoothness. The sliding window technique is typically used for constructing ultrasound parametric and Nakagami images. Using a large window overlap ratio may improve the WMC Nakagami image resolution but reduces computational efficiency. Therefore, the objectives of this study include: (i) exploring the effects of the window overlap ratio on the resolution and smoothness of WMC Nakagami images; (ii) proposing a fast algorithm that is based on the convolution operator (FACO) to accelerate WMC Nakagami imaging. Computer simulations and preliminary clinical tests on liver fibrosis samples (n=48) were performed to validate the FACO-based WMC Nakagami imaging. The results demonstrated that the width of the autocorrelation function and the parameter distribution of the WMC Nakagami image reduce with the increase in the window overlap ratio. One-pixel shifting (i.e., sliding the window on the image data in steps of one pixel for parametric imaging) as the maximum overlap ratio significantly improves the WMC Nakagami image quality. Concurrently, the proposed FACO method combined with a computational platform that optimizes the matrix computation can accelerate WMC Nakagami imaging, allowing the detection of liver fibrosis-induced changes in envelope statistics. FACO-accelerated WMC Nakagami imaging is a new-generation Nakagami imaging technique with an improved image quality and fast computation.

Acoustic Structure Quantification Analysis of the Thyroid in Patients with Diffuse Autoimmune Thyroid Disease

The aim of this study was to assess whether acoustic structure quantification (ASQ) can differentiate normal from pathological thyroid parenchyma in patients with diffuse autoimmune thyroid disease (AITD). We evaluated 83 subjects (72 [87%] women and 11 [13%] men) aged 19 to 94 years with a mean age of 53 years. We performed a prospective study (from March 2011 to November 2014) that included 43 (52%) patients with chronic autoimmune thyroiditis (CAT), 22 (26%) patients with Graves' disease (GD), and 18 (22%) healthy volunteers. The ASQ values were significantly lower in normal subjects than in subjects with CAT and GD (p < 0.001). In contrast, the differences between the GD and the CAT patients (p = 0.23) were not statistically significant. The optimal cutoff ASQ value for which the sum of sensitivity and specificity was the highest for the prediction of diffuse thyroid pathology was 103 (95% confidence interval = [0.79, 0.95]). At this cutoff value, the sensitivity was 83% and the specificity was 89%. Our findings suggest that ASQ is a useful method for the assessment of the thyroid in patients with AITD.

Non-invasive assessment of liver fibrosis using acoustic structure quantification: comparison with transient elastography in chronic viral hepatitis

PURPOSE

The purpose of this study was to evaluate the diagnostic efficacy of acoustic structure quantification (ASQ) parameters [mode, average, and focal distribution (FD) ratio] in the staging of hepatic fibrosis in patients with chronic viral hepatitis and to compare it with transient elastography (TE) by using liver biopsy as reference standard.

METHODS

We studied 62 patients with chronic viral hepatitis. Each patient underwent ASQ evaluation and liver biopsy; 54 of these patients received TE. Thirty-six participants without any liver disease were enrolled as normal group, who also underwent ASQ evaluation and TE. All three parameters of ASQ were compared with the histologic fibrosis grade according to the METAVIR scoring (F0-F4). Statistical analysis was performed to investigate the correlations and the diagnostic values of ASQ parameters and compare them to TE.

RESULTS

All three ASQ parameters and TE were significantly correlated with liver fibrosis stage. Of the ASQ parameters, the mode parameter showed the best correlation (P < 0.001). On the area under the receiver operating characteristic curve (AUROC), the mode parameter of ASQ analysis showed both significant correlation and good accuracy for diagnosis of F ≥ 1, F ≥ 2, and F ≥ 3. These values were significantly better than those of the average and FD ratio parameters in F ≥ 1 and F ≥ 2 (P < 0.05). There was no statistically significant difference in AUROC between the mode parameter and TE in diagnosis of F ≥ 1, F ≥ 2, or F ≥ 3.

CONCLUSIONS

The mode parameter is the most reliable ASQ parameter, comparable to TE, as a non-invasive method for the detection and grading of liver fibrosis in patients with chronic viral hepatitis.

Speed of sound in diseased liver observed by scanning acoustic microscopy with 80 MHz and 250 MHz

In this study, the speed of sound (SOS) of two types of rat livers (eight normal livers, four cirrhotic livers) was measured with a scanning acoustic microscope using two transducers, one of which had an 80-MHz and the other a 250-MHz center frequency. The 250-MHz transducer had a better spatial resolution adapted to studying fiber or hepatic parenchymal cells. In normal livers, averages of the SOS values were from 1598 to 1677 m/s at 80-MHz and from 1568 to 1668 m/s at 250-MHz. In the fiber tissue of cirrhotic livers, averages of the SOS values were from 1645 to 1658 m/s at 80-MHz and from 1610 to 1695 m/s at 250-MHz, while the SOS values in the other tissue of cirrhotic livers ranged from 1644 to 1709 m/s at 80-MHz and from 1641 to 1715 m/s at 250-MHz. In one liver, SOS in fiber tissue was larger than that of tissues without fiber while in others it was lower. The resulting two-dimensional SOS maps provide a unique quantitative insight of liver acoustic microstructures in a healthy liver and in a cirrhotic ones. This study would be helpful to understand the complex relationship between acoustic properties and liver disease including fiber tissue.

Comparison of Acoustic Structure Quantification (ASQ), shearwave elastography and histology in patients with diffuse hepatopathies

Background

Objective of the study was to evaluate the diagnostic value of novel ultrasonographic modalities in comparison with simultaneously performed liver biopsy.

Methods

The results of simultaneously performed examinations using Acoustic Structure Quantification (ASQ), Virtual Touch Imaging and Quantification (VTIQ) and Virtual Touch Tissue Quantification (VTTQ) were compared with the findings of liver biopsy in patients with a wide variety of diffuse hepatopathies (n = 51). The histologically determined fibrosis stage according to Desmet and Scheuer was compared with quantitative measurements returned by the ultrasonographic imaging modalities.

Results

No statistically significant correlation with histologically determined fibrosis stage could be identified for any measurements returned using ASQ. Increasing severity of hepatic steatosis, however, was associated with a reduction in the focal disturbance (FD) ratio (r = −0.55; p < 0.0001). The shearwave velocities measured using VTTQ satisfyingly correlated with fibrosis stage (r = 0.56; p > 0.0001). Fibrosis stages > F2 were associated with an area under the curve (AUC) of 0.94 (95 %-CI:0.84–0.99). A cut-off value for shearwave velocity of 1.66 m/s was determined with a sensitivity of 100 % and a specificity of 84 %. VTIQ showed a less pronounced but acceptable correlation with fibrosis stage (r = 0.35; p = 0.0154). For fibrosis stages > F2 analysis showed an AUC of 0.84 (95 %-CI:0.70–0.93). The cut-off value was 1.82 m/s with a sensitivity of 100 % and a specificity of 58 %.

Conclusion

While ASQ showed no diagnostic advantage in our patient collective, VTTQ showed high reliability for determining severe liver fibrosis in a group of patients with diffuse liver diseases of different etiology.

Using Acoustic Structure Quantification During B-Mode Sonography for Evaluation of Hashimoto Thyroiditis

OBJECTIVES

This study aimed to evaluate the usefulness of Acoustic Structure Quantification (ASQ; Toshiba Medical Systems Corporation, Nasushiobara, Japan) values in the diagnosis of Hashimoto thyroiditis using B-mode sonography and to identify a cutoff ASQ level that differentiates Hashimoto thyroiditis from normal thyroid tissue.

METHODS

A total of 186 thyroid lobes with Hashimoto thyroiditis and normal thyroid glands underwent sonography with ASQ imaging. The quantitative results were reported in an echo amplitude analysis (Cm(2)) histogram with average, mode, ratio, standard deviation, blue mode, and blue average values. Receiver operating characteristic curve analysis was performed to assess the diagnostic ability of the ASQ values in differentiating Hashimoto thyroiditis from normal thyroid tissue. Intraclass correlation coefficients of the ASQ values were obtained between 2 observers.

RESULTS

Of the 186 thyroid lobes, 103 (55%) had Hashimoto thyroiditis, and 83 (45%) were normal. There was a significant difference between the ASQ values of Hashimoto thyroiditis glands and those of normal glands (P < .001). The ASQ values in patients with Hashimoto thyroiditis were significantly greater than those in patients with normal thyroid glands. The areas under the receiver operating characteristic curves for the ratio, blue average, average, blue mode, mode, and standard deviation were: 0.936, 0.902, 0.893, 0.855, 0.846, and 0.842, respectively. The ratio cutoff value of 0.27 offered the best diagnostic performance, with sensitivity of 87.38% and specificity of 95.18%. The intraclass correlation coefficients ranged from 0.86 to 0.94, which indicated substantial agreement between the observers.

CONCLUSIONS

Acoustic Structure Quantification is a useful and promising sonographic method for diagnosing Hashimoto thyroiditis. Not only could it be a helpful tool for quantifying thyroid echogenicity, but it also would be useful for diagnosis of Hashimoto thyroiditis.

Assessment of liver fibrosis in chronic hepatitis B using acoustic structure quantification: quantitative morphological ultrasound

OBJECTIVES

To prospectively investigate the usefulness of acoustic structure quantification (ASQ) for noninvasive assessment of liver fibrosis in patients with chronic hepatitis B (CHB).

METHODS

Consecutive patients with CHB scheduled for liver biopsy or partial liver resection underwent standardized ASQ examinations. The ASQ parameter, named focal disturbance (FD) ratio, were compared with METAVIR scores. The analysis was based on receiver operating characteristic (ROC) curves and multiple regression analysis.

RESULTS

A total of 114 patients were enrolled in the final analysis. The area under the ROC curve for the FD ratio was 0.84 for significant fibrosis (≥ F2), 0.86 for severe fibrosis (≥ F3), and 0.83 for cirrhosis (= F4). The optimal cutoff values for the FD ratio were 0.25, 0.30 and 0.50 for fibrosis stages ≥ F2, ≥ F3 and = F4, respectively. The prevalence of a difference of at least two stages between the FD ratio and the histological stage was 12.3 % (14 of 114). The fibrosis stage (P < 0.001), degree of steatosis (P < 0.001) were independent factors associated with the FD ratio.

CONCLUSIONS

FD ratio should be an effective noninvasive imaging biomarker for the assessment of liver fibrosis in patients with CHB.

KEY POINTS

• Focal disturbance (FD) ratio increased with the increasing histological fibrosis stages. • FD ratio showed promising diagnostic accuracy in assessing liver fibrosis. • Degree of fibrosis and steatosis were independent factors associated with FD ratio.

Impact factors and the optimal parameter of acoustic structure quantification in the assessment of liver fibrosis

The aims of the present study are to assess the impact factors on acoustic structure quantification (ASQ) ultrasound and find the optimal parameter for the assessment of liver fibrosis. Twenty healthy volunteers underwent ASQ examinations to evaluate impact factors in ASQ image acquisition and analysis. An additional 113 patients with liver diseases underwent standardized ASQ examinations, and the results were compared with histologic staging of liver fibrosis. We found that the right liver displayed lower values of ASQ parameters than the left (p = 0.000-0.021). Receive gain experienced no significant impact except gain 70 (p = 0.193-1.000). With regard to different diameter of involved vessels in regions of interest, the group ≤2.0 mm differed significantly with the group 2.1-5.0 mm (p = 0.000-0.033) and the group >5.0 mm (p = 0.000-0.062). However, the region of interest size (p = 0.438-1.000) and depth (p = 0.072-0.764) had no statistical impact. Good intra- and inter-operator reproducibilities were found in both image acquisitions and offline image analyses. In the liver fibrosis study, the focal disturbance ratio had the highest correlation with histologic fibrosis stage (r = 0.67, p < 0.001). In conclusion, the testing position, receive gain and involved vessels were the main factors in ASQ examinations and focal disturbance ratio was the optimal parameter in the assessment of liver fibrosis.

Estimating steatosis and fibrosis: Comparison of acoustic structure quantification with established techniques

AIM: To compare ultrasound-based acoustic structure quantification (ASQ) with established non-invasive techniques for grading and staging fatty liver disease.

METHODS: Type 2 diabetic patients at risk of non-alcoholic fatty liver disease (n = 50) and healthy volunteers (n = 20) were evaluated using laboratory analysis and anthropometric measurements, transient elastography (TE), controlled attenuation parameter (CAP), proton magnetic resonance spectroscopy (¹H-MRS; only available for the diabetic cohort), and ASQ. ASQ parameters mode, average and focal disturbance (FD) ratio were compared with: (1) the extent of liver fibrosis estimated from TE and non-alcoholic fatty liver disease (NAFLD) fibrosis scores; and (2) the amount of steatosis, which was classified according to CAP values.

RESULTS: Forty-seven diabetic patients (age 67.0 ± 8.6 years; body mass index 29.4 ± 4.5 kg/m²) with reliable CAP measurements and all controls (age 26.5 ± 3.2 years; body mass index 22.0 ± 2.7 kg/m²) were included in the analysis. All ASQ parameters showed differences between healthy controls and diabetic patients (P < 0.001, respectively). The ASQ FD ratio (logarithmic) correlated with the CAP (r = -0.81, P < 0.001) and ¹H-MRS (r = -0.43, P = 0.004) results. The FD ratio [CAP < 250 dB/m: 107 (102-109), CAP between 250 and 300 dB/m: 106 (102-114); CAP between 300 and 350 dB/m: 105 (100-112), CAP ≥ 350 dB/m: 102 (99-108)] as well as mode and average parameters, were reduced in cases with advanced steatosis (ANOVA P < 0.05). However, none of the ASQ parameters showed a significant difference in patients with advanced fibrosis, as determined by TE and the NAFLD fibrosis score (P > 0.08, respectively).

CONCLUSION: ASQ parameters correlate with steatosis, but not with fibrosis in fatty liver disease. Steatosis estimation with ASQ should be further evaluated in biopsy-controlled studies.

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.

Acoustic structure quantification ultrasound software proves imprecise in assessing liver fibrosis or cirrhosis in parenchymal liver diseases

The present study was conducted to assess the diagnostic accuracy of Acoustic Structure Quantification (ASQ) ultrasound software in liver biopsy of patients with liver fibrosis and cirrhosis. Eighty patients (47 ± 14 y, 41 men) with chronic liver diseases underwent ultrasound examination of the liver and liver biopsy. In addition to the standard-care ultrasound examination, three valid gray-scale images were obtained for each patient. With the ASQ software, the average and peak values (Cm(2)) of each ultrasound gray-scale image were calculated and then compared with histologic fibrosis staging (F0-F4). No correlation was found between ASQ values and histologic fibrosis stage (p > 0.05). Areas under the curve for the diagnosis of no or mild fibrosis (F0 and F1), moderate/severe fibrosis (F2 and F3) and cirrhosis (F4) using average/peak Cm(2) values of small regions of interest were 0.46/0.43, 0.62/0.68 and 0.38/0.33. Determination of liver fibrosis with ASQ in its present form as an alternative approach to liver biopsy is too imprecise.

Non-invasive diagnosis of alcoholic liver disease

Alcoholic liver disease (ALD) is the most common liver disease in the Western world. For many reasons, it is underestimated and underdiagnosed. An early diagnosis is absolutely essential since it (1) helps to identify patients at genetic risk for ALD; (2) can trigger efficient abstinence namely in non-addicted patients; and (3) initiate screening programs to prevent life-threatening complications such as bleeding from varices, spontaneous bacterial peritonitis or hepatocellular cancer. The two major end points of ALD are alcoholic liver cirrhosis and the rare and clinically-defined alcoholic hepatitis (AH). The prediction and early diagnosis of both entities is still insufficiently solved and usually relies on a combination of laboratory, clinical and imaging findings. It is not widely conceived that conventional screening tools for ALD such as ultrasound imaging or routine laboratory testing can easily overlook ca. 40% of manifest alcoholic liver cirrhosis. Non-invasive methods such as transient elastography (Fibroscan), acoustic radiation force impulse imaging or shear wave elastography have significantly improved the early diagnosis of alcoholic cirrhosis. Present algorithms allow either the exclusion or the exact definition of advanced fibrosis stages in ca. 95% of patients. The correct interpretation of liver stiffness requires a timely abdominal ultrasound and actual transaminase levels. Other non-invasive methods such as controlled attenuation parameter, serum levels of M30 or M65, susceptometry or breath tests are under current evaluation to assess the degree of steatosis, apoptosis and iron overload in these patients. Liver biopsy still remains an important option to rule out comorbidities and to confirm the prognosis namely for patients with AH.

Ultrasound in chronic liver disease

Background

With the high prevalence of diffuse liver disease there is a strong clinical need for noninvasive detection and grading of fibrosis and steatosis as well as detection of complications.

Methods

B-mode ultrasound supplemented by portal system Doppler and contrast-enhanced ultrasound are the principal techniques in the assessment of liver parenchyma and portal venous hypertension and in hepatocellular carcinoma surveillance.

Results

Fibrosis can be detected and staged with reasonable accuracy using Transient Elastography and Acoustic Radiation Force Imaging. Newer elastography techniques are emerging that are undergoing validation and may further improve accuracy. Ultrasound grading of hepatic steatosis currently is predominantly qualitative.

Conclusion

A summary of methods including B-mode, Doppler, contrast-enhanced ultrasound and various elastography techniques, and their current performance in assessing the liver, is provided.

Teaching Points

• Diffuse liver disease is becoming more prevalent and there is a strong clinical need for noninvasive detection.

• Portal hypertension can be best diagnosed by demonstrating portosystemic collateral venous flow.

• B-mode US is the principal US technique supplemented by portal system Doppler.

• B-mode US is relied upon in HCC surveillance, and CEUS is useful in the evaluation of possible HCC.

• Fibrosis can be detected and staged with reasonable accuracy using TE and ARFI.

• US detection of steatosis is currently reasonably accurate but grading of severity is of limited accuracy.

Acoustic structure quantification (ASQ): a new tool in sonographic examination of liver lesions in hepatic alveolar echinococcosis

PURPOSE

Qualitative and quantitative acoustic structure quantification (ASQ) is a new, noninvasive sonographic imaging method based on B-mode. This prospective clinical pilot study aims to answer the question whether delineation and measurement of liver lesions in hepatic alveolar echinococcosis (HAE) can be improved by ASQ. Furthermore, this is the first pilot study to explore how ASQ parameters in HAE lesions develop.

METHODS

A total of 24 patients (male = 13/female = 11, mean age = 52 years (16-85), mean disease duration = 68 months (1-334)) with HAE were examined with ASQ using a Toshiba Aplio 500 unit. ASQ parameters were measured in HAE liver lesions and in adjacent non-tumor parenchyma. Quantitative analysis was performed offline using ASQ quantification software.

RESULTS

Subjectively parasitic tumors in HAE appear more prominent in color-coded ASQ imaging, but the size of lesions measured in ASQ mode does not differ from size measurements in B-mode. Median focal disturbance ratio (FD ratio) in lesions was 3 (0.1-3), compared with 0.5 (0.1-1.8) in surrounding liver parenchyma (p < 0.0001). Statistical comparison of other ASQ parameters (mode, average, standard deviation) shows results that are similarly significant with p values between p < 0.0001 and p < 0.0018.

CONCLUSION

ASQ is a promising sonographic method for examination and quantification of structural changes of liver parenchyma in HAE lesions.