Special Issue "Ultrasound Elastography"

A special issue of Applied Sciences (ISSN 2076-3417). This special issue belongs to the section "Acoustics and Vibrations".

Deadline for manuscript submissions: closed (31 March 2018)

Special Issue Editor

Guest Editor
Prof. Dr. med. Christoph F. Dietrich

Caritas Krankenhaus Bad Mergentheim, Uhlandstr. 7 , 97980 Bad Mergentheim, Germany
Website | E-Mail
Phone: 49 (0)7931 58-2201 / 2200
Fax: 49 (0)7931-58-2290
Interests: elastography; endoscopy; endoscopic ultrasound; contrast enhanced ultrasound; hepatitis; cancer

Special Issue Information

Dear Colleagues,

As Guest Editor I am happy to invite authors from all over the world to contribute original data or review to a Special Issue on "Ultrasound Elastography" in the open access journal Applied Sciences (ISSN 2076-3417). High quality papers will be free of charge.

The European Federation of Societies for Ultrasound in Medicine and Biology (EFSUMB) published the first elastography guidelines in 2013 (basic principles, clinical applications) and the most current liver update (2017), which has been followed by the elastography guidelines from the World Federation for Ultrasound in Medicine and Biology (WFUMB) (basic principles, liver, breast, thyroid and prostate). The comparison between methods, evaluation of portal hypertension and many other questions are still open issues in liver elastography. New elastographic applications are under evaluation and close to being used in clinical practice. Strain imaging has been incorporated into many disciplines and EFSUMB guidelines are under preparation. More research is necessary for improved evidence for clinical applications in daily practice. Please consider submitting your high-quality papers for this Special Issue.

Prof. Christoph F. Dietrich, MBA
EFSUMB President 2013–2015
Guest Editor

Manuscript Submission Information

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Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1500 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Elastography

  • strain

  • Liver stiffness

  • shear waves

  • stiffness

  • thyroid

  • prostate

  • breast

  • musculoskeletal

  • pancreas

Published Papers (11 papers)

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Editorial

Jump to: Research, Review

Open AccessEditorial Editorial on the Special Issue of Applied Sciences on the Topic of Elastography
Appl. Sci. 2018, 8(8), 1232; https://doi.org/10.3390/app8081232
Received: 20 June 2018 / Accepted: 17 July 2018 / Published: 26 July 2018
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(This article belongs to the Special Issue Ultrasound Elastography)

Research

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Open AccessArticle Strain Ratio as a Quantification Tool in Strain Imaging
Appl. Sci. 2018, 8(8), 1273; https://doi.org/10.3390/app8081273
Received: 22 June 2018 / Revised: 20 July 2018 / Accepted: 23 July 2018 / Published: 1 August 2018
Cited by 1 | PDF Full-text (3841 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Ultrasound-based strain imaging is available in several ultrasound (US) scanners. Strain ratio (SR) can be used to quantify the strain recorded simultaneously in two different user-selected areas, ideally exposed to the same amount of stress. The aim of this study was [...] Read more.
Ultrasound-based strain imaging is available in several ultrasound (US) scanners. Strain ratio (SR) can be used to quantify the strain recorded simultaneously in two different user-selected areas, ideally exposed to the same amount of stress. The aim of this study was to evaluate SR variability when assessed in an in-vitro setup with a tissue-mimicking phantom on resected tissue samples and in live tissue scanning with endoscopic applications. We performed an in vivo retrospective analysis of SR variability used for quantification of elastic contrasts in a tissue-mimicking phantom containing four homogenous inclusion in 38 resected bowel wall lesions and 48 focal pancreatic lesions. Median SR and the inter-quartile range (IQR) were calculated for all external and endoscopic ultrasound (EUS) applications. The IQR and median provide a measure of SR variability focusing on the two percentiles of the data closest to the median value. The overall SR variability was lowest in a tissue-mimicking phantom (mean QR/median SR: 0.07). In resected bowel wall lesions representing adenomas, adenocarcinomas, or Crohn lesions, the variability increased (mean IQR/Median: 0.62). During an in vivo endoscopic examination of focal pancreatic lesions, the variability increased further (mean IQR/Median: 2.04). SR variability increased when assessed for different targets with growing heterogeneity and biological variability from homogeneous media to live tissues and endoscopic application. This may indicate a limitation for the accuracy of SR evaluation in some clinical applications. Full article
(This article belongs to the Special Issue Ultrasound Elastography)
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Graphical abstract

Open AccessFeature PaperArticle Shear Wave Elastography Measures of the Achilles Tendon: Influence of Time of Day, Leg Dominance and the Impact of an Acute 30-Minute Bout of Running
Appl. Sci. 2018, 8(7), 1170; https://doi.org/10.3390/app8071170
Received: 27 June 2018 / Revised: 13 July 2018 / Accepted: 16 July 2018 / Published: 18 July 2018
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Abstract
The mechanical properties of human tendons are likely to be influenced by factors known to affect elastic structures, including patterns of loading and unloading during the day. However, the exact scale and relevance of these variables to tendon stiffness remains unclear. The aim [...] Read more.
The mechanical properties of human tendons are likely to be influenced by factors known to affect elastic structures, including patterns of loading and unloading during the day. However, the exact scale and relevance of these variables to tendon stiffness remains unclear. The aim of this study was to (1) measure Achilles tendon (AT) stiffness over the course of the day, (2) examine AT stiffness between dominant and non-dominant standing leg tendons and (3) assess the impact of previous activity on AT stiffness. To assess the impact of time of day and leg dominance, 15 healthy participants (6 females, 9 males; mean age 28 ± 4 year, mean VISA-A score 99.0 ± 1.2) had shear wave elastography (SWE) measures taken at 08:00 h, 12:30 h and 17:00 h on both dominant and non-dominant legs. To assess the impact of exercise, 24 tendons were analysed (7 females, 5 males; mean age 27 ± 4 year, mean VISA-A Score 99.1 ± 1.1) with participants randomly assigned to either a control (CONT) group or a running (RUN) group. The RUN group performed a 30-min run at a subjective intensity of 13–15 on rating of perceived exertion (RPE) scale and had SWE measures taken before, immediately after, 6 h 24 h, 48 h and 72 h following the run. There were no significant differences in AT stiffness over the course of a day or between dominant and non-dominant leg. Significant increases in AT stiffness were noted pre-post run (0.27 m/s, 2.95%, p = 0.037). Leg dominance does not affect SWE values from asymptomatic ATs or change throughout a day, but a 30-min run significantly increases AT stiffness. Leg dominance and timing of clinical appointments are unlikely to affect SWE results, however a prior bout of physical activity may cause changes within the AT resulting in a significantly different SWE measure. Clinicians and researchers should be cautious of interpreting SWE results if weight bearing exercise has been performed beforehand. Full article
(This article belongs to the Special Issue Ultrasound Elastography)
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Open AccessArticle A Novel Method for Assessing Regional Tendon Stiffness and Its Significance
Appl. Sci. 2018, 8(7), 1156; https://doi.org/10.3390/app8071156
Received: 26 May 2018 / Revised: 25 June 2018 / Accepted: 27 June 2018 / Published: 17 July 2018
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Abstract
Elastography can be used to estimate the regional shear modulus of a tendon. This can advance our knowledge on the impact of patellar alignment and regional patellar tendon stiffness. This is important as patellar tendon abnormality is mainly found in the medial portion [...] Read more.
Elastography can be used to estimate the regional shear modulus of a tendon. This can advance our knowledge on the impact of patellar alignment and regional patellar tendon stiffness. This is important as patellar tendon abnormality is mainly found in the medial portion of the tendon in subjects with proximal patellar tendinopathy. This paper aims to assess the effect of patellar displacement on differential modulation on the shear modulus of the patellar tendon. Shear modulus is captured on the medial and lateral half of the patella tendon using the Axiplorer® ultrasound unit in conjunction with a 4–15 MHz, 50 mm linear transducer with the patellar being positioned in its resting, medio- and laterally displaced positions on 40 adults (19 females, 21 males). When the patellar is displaced laterally, the shear modulus is significantly increased at the medial half in both genders but decreased at the lateral half only in females. Conclusions: Elastography detects changes in regional tendon stiffness associated with alteration in patellar positions. The modulation on the shear modulus is gender and region specific. Full article
(This article belongs to the Special Issue Ultrasound Elastography)
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Open AccessArticle Quantitative Analysis of Patellar Tendon Abnormality in Asymptomatic Professional “Pallapugno” Players: A Texture-Based Ultrasound Approach
Appl. Sci. 2018, 8(5), 660; https://doi.org/10.3390/app8050660
Received: 30 March 2018 / Revised: 20 April 2018 / Accepted: 23 April 2018 / Published: 25 April 2018
Cited by 1 | PDF Full-text (2241 KB) | HTML Full-text | XML Full-text
Abstract
Abnormalities in B-mode ultrasound images of the patellar tendon often take place in asymptomatic athletes but it is still not clear if these modifications forego or can predict the development of tendinopathy. Subclinical tendinopathy can be arbitrarily defined as either (1) the presence [...] Read more.
Abnormalities in B-mode ultrasound images of the patellar tendon often take place in asymptomatic athletes but it is still not clear if these modifications forego or can predict the development of tendinopathy. Subclinical tendinopathy can be arbitrarily defined as either (1) the presence of light structural changes in B-mode ultrasound images in association with mild neovascularization (determined with Power Doppler images) or (2) the presence of moderate/severe structural changes with or without neovascularization. Up to now, the structural changes and neovascularization of the tendon are evaluated qualitatively by visual inspection of ultrasound images. The aim of this study is to investigate the capability of a quantitative texture-based approach to determine tendon abnormality of “pallapugno” players. B-mode ultrasound images of the patellar tendon were acquired in 14 players and quantitative texture parameters were calculated within a Region of Interest (ROI) of both the non-dominant and the dominant tendon. A total of 90 features were calculated for each ROI, including 6 first-order descriptors, 24 Haralick features, and 60 higher-order spectra and entropy features. These features on the dominant and non-dominant side were used to perform a multivariate linear regression analysis (MANOVA) and our results show that the descriptors can be effectively used to determine tendon abnormality and, more importantly, the occurrence of subclinical tendinopathy. Full article
(This article belongs to the Special Issue Ultrasound Elastography)
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Open AccessArticle Ultrasound-Based Liver Stiffness Surveillance in Patients Treated for Chronic Hepatitis B or C
Appl. Sci. 2018, 8(4), 626; https://doi.org/10.3390/app8040626
Received: 9 March 2018 / Revised: 30 March 2018 / Accepted: 30 March 2018 / Published: 17 April 2018
Cited by 1 | PDF Full-text (272 KB) | HTML Full-text | XML Full-text
Abstract
Evolving modes of ultrasound-based elastography have achieved promising validity and reliability for evaluating liver fibrosis. Liver stiffness (LS) is a valuable biomarker for modeling liver disease progression and regression on a continuous noncategorical scale as changes in LS per year or for determining [...] Read more.
Evolving modes of ultrasound-based elastography have achieved promising validity and reliability for evaluating liver fibrosis. Liver stiffness (LS) is a valuable biomarker for modeling liver disease progression and regression on a continuous noncategorical scale as changes in LS per year or for determining the LS progression or regression rate for refining LS measurement (LSM)-based prognostics. The paradigm of LSMs has altered the focus from liver fibrosis staging alone to comprehensive liver-relevant risk estimations. However, diverse ranges of cohort characteristics, disease types, surveillance protocols and timeframes, necroinflammatory resolutions or biochemical responses (BRs), factors explaining the magnitude or kinetics in LS change, virologic responses (VRs), fibrosis reversals (FRs), and noninvasive surveillance results have rarely been reviewed collectively. Elastography-based LS surveillance alone conveys chronological and valuable patient information and assists in characterizing worldwide patient cohorts under antiviral treatment by delineating the concurrent time elapsed, VR, BR, and FR. In groups with uniform VRs to direct-acting antivirals for chronic hepatitis C and nucleoside and nucleotide analogs for chronic hepatitis B, decline in LS can be explained using concurrent BR from 24 weeks to 3 years, followed by FR and the time elapsed. Full article
(This article belongs to the Special Issue Ultrasound Elastography)
Open AccessArticle Non-Invasive Assessment of Hepatic Fibrosis by Elastic Measurement of Liver Using Magnetic Resonance Tagging Images
Appl. Sci. 2018, 8(3), 437; https://doi.org/10.3390/app8030437
Received: 11 February 2018 / Revised: 4 March 2018 / Accepted: 7 March 2018 / Published: 14 March 2018
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Abstract
To date, the measurement of the stiffness of liver requires a special vibrational tool that limits its application in many hospitals. In this study, we developed a novel method for automatically assessing the elasticity of the liver without any use of contrast agents [...] Read more.
To date, the measurement of the stiffness of liver requires a special vibrational tool that limits its application in many hospitals. In this study, we developed a novel method for automatically assessing the elasticity of the liver without any use of contrast agents or mechanical devices. By calculating the non-rigid deformation of the liver from magnetic resonance (MR) tagging images, the stiffness was quantified as the displacement of grids on the liver image during a forced exhalation cycle. Our methods include two major processes: (1) quantification of the non-rigid deformation as the bending energy (BE) based on the thin-plate spline method in the spatial domain and (2) calculation of the difference in the power spectrum from the tagging images, by using fast Fourier transform in the frequency domain. By considering 34 cases (17 normal and 17 abnormal liver cases), a remarkable difference between the two groups was found by both methods. The elasticity of the liver was finally analyzed by combining the bending energy and power spectral features obtained through MR tagging images. The result showed that only one abnormal case was misclassified in our dataset, which implied our method for non-invasive assessment of liver fibrosis has the potential to reduce the traditional liver biopsy. Full article
(This article belongs to the Special Issue Ultrasound Elastography)
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Open AccessArticle Effect of HCV Core Antigen and RNA Clearance during Therapy with Direct Acting Antivirals on Hepatic Stiffness Measured with Shear Wave Elastography in Patients with Chronic Viral Hepatitis C
Appl. Sci. 2018, 8(2), 198; https://doi.org/10.3390/app8020198
Received: 19 December 2017 / Revised: 26 January 2018 / Accepted: 26 January 2018 / Published: 29 January 2018
Cited by 2 | PDF Full-text (982 KB) | HTML Full-text | XML Full-text
Abstract
To assess a combination of novel measures of therapeutic success in the treatment of chronic hepatitis C (CHC) infection, we evaluated liver stiffness (LS) with shear wave elastography and hepatitis C virus core antigen (HCVcAg) concentrations. We followed 34 patients during and after [...] Read more.
To assess a combination of novel measures of therapeutic success in the treatment of chronic hepatitis C (CHC) infection, we evaluated liver stiffness (LS) with shear wave elastography and hepatitis C virus core antigen (HCVcAg) concentrations. We followed 34 patients during and after treatment with direct acting antivirals. All patients achieved a sustained virologic and serologic response and a significant increase of albumin levels. Decreases of alanine aminotransferase (ALT) activity and alpha-fetoprotein (AFP) level were observed during the treatment and follow-up period. A significant decrease in LS was observed between baseline, end of treatment (EOT), and at 24- and 96-week post-treatment follow-up. LS decline between EOT and 96-week follow-up (FU96) was observed in 79% of patients. Significant LS changes were seen in patients with advanced fibrosis, particularly in cirrhotics and in patients with ALT exceeding 100 IU/mL. There was a positive correlation between ALT activity and LS changes at the baseline versus FU96. A negative correlation was demonstrated between individual HCVcAg baseline concentrations and reduction of LS at the baseline versus FU96. In conclusion, we observed that LS significantly declined during and after antiviral treatment. It was accompanied by improvement in some liver function measures, and disappearance of both HCVcAg and HCV ribonucleic acid (HCV RNA). Full article
(This article belongs to the Special Issue Ultrasound Elastography)
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Open AccessArticle Interpretation US Elastography in Chronic Hepatitis B with or without Anti-HBV Therapy
Appl. Sci. 2017, 7(11), 1164; https://doi.org/10.3390/app7111164
Received: 15 September 2017 / Revised: 29 October 2017 / Accepted: 30 October 2017 / Published: 13 November 2017
Cited by 1 | PDF Full-text (1155 KB) | HTML Full-text | XML Full-text
Abstract
Inflammation has significant impacts on liver fibrosis measurement by ultrasound elastography. The interpretation requires further optimization in patients with or without anti-viral therapy. We prospectively enrolled a consecutive series of patients with chronic hepatitis B who received liver histology analysis and acoustic radiation [...] Read more.
Inflammation has significant impacts on liver fibrosis measurement by ultrasound elastography. The interpretation requires further optimization in patients with or without anti-viral therapy. We prospectively enrolled a consecutive series of patients with chronic hepatitis B who received liver histology analysis and acoustic radiation force impulse (ARFI). 146 patients who underwent liver biopsy (50.9%) or tumor resection (49.1%) were enrolled. 34 patients (23.3%) had been receiving anti-hepatitis B therapy of various duration. The areas under the receiver-operating characteristic (AUROC) for the diagnosis of Metavir F4 by mean ARFI was 0.820 in the non-treatment group and 0.796 in the treatment group. The ARFI tended to be not lower (100%) than the corresponding Metavir grading in patients with treatment within 12 months, equal (75%) from 13 to 31 months, and lower (71.4%) after 32 months. We conclude that ARFI is a reliable tool for measurement of liver fibrosis in chronic hepatitis B patients with ALT (alanine aminotransferase) <5x the upper limit of normal. For those patients under anti-HBV therapy, the optimal timing for ARFI analysis will be over 1–2.5 years of nucleos(t)ide analogue therapy. The ARFI measurement after 2.5 years tends to be lower than the corresponding histology grading. Full article
(This article belongs to the Special Issue Ultrasound Elastography)
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Open AccessArticle Shear Wave Elastography Combining with Conventional Grey Scale Ultrasound Improves the Diagnostic Accuracy in Differentiating Benign and Malignant Thyroid Nodules
Appl. Sci. 2017, 7(11), 1103; https://doi.org/10.3390/app7111103
Received: 11 September 2017 / Revised: 30 September 2017 / Accepted: 13 October 2017 / Published: 25 October 2017
Cited by 3 | PDF Full-text (1845 KB) | HTML Full-text | XML Full-text
Abstract
Shear wave elastography provides information about the stiffness of thyroid nodules that could be a new indicator of malignancy. The current study aimed to investigate the feasibility of using shear wave elastography (SWE) alone and in conjunction with grey scale ultrasound (GSU) to [...] Read more.
Shear wave elastography provides information about the stiffness of thyroid nodules that could be a new indicator of malignancy. The current study aimed to investigate the feasibility of using shear wave elastography (SWE) alone and in conjunction with grey scale ultrasound (GSU) to predict malignancy in 111 solitary thyroid nodules. Malignant thyroid nodules tended to have microcalcification, hypoechogenicity, tall to width ratio >1, and irregular borders (p < 0.05). SWE indices (Emaximum and Emean) of malignant nodules (median ± standard error: 85.2 ± 8.1 kPa and 26.6 ± 2.5 kPa) were significantly higher than those of benign nodules (median ± standard error: 50.3 ± 3.1 kPa and 20.2 ± 1 kPa) (p < 0.05). The optimal cut-off of Emaximum and Emean for distinguishing benign and malignant nodules was 67.3 kPa and 23.1 kPa, respectively. Diagnostic performances for GSU + Emaximum, GSU + Emean, GSU, Emaximum and Emean were: 70.4%, 74.1%, 96.3%, 70.4% and 74.1% for sensitivity, 83.3%, 79.8%, 46.4%, 70.2%, and 66.7% for specificity, and 80.2%, 78.4%, 58.5%, 70.3%, and 68.5% for accuracy, respectively. Our results suggested that combining GSU with SWE (using Emaximum or Emean) increased the overall diagnostic accuracy in distinguishing benign and malignant thyroid nodules. Full article
(This article belongs to the Special Issue Ultrasound Elastography)
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Review

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Open AccessReview Current Knowledge in Ultrasound-Based Liver Elastography of Pediatric Patients
Appl. Sci. 2018, 8(6), 944; https://doi.org/10.3390/app8060944
Received: 2 April 2018 / Revised: 21 May 2018 / Accepted: 28 May 2018 / Published: 7 June 2018
Cited by 2 | PDF Full-text (1105 KB) | HTML Full-text | XML Full-text
Abstract
Studies performed using transient elastography (TE), point shear wave elastography (pSWE) and two-dimensional shear wave elastography (2D-SWE) have shown that these techniques are all feasible and accurate in children for the evaluation of liver fibrosis due to several etiologies. However, for some specific [...] Read more.
Studies performed using transient elastography (TE), point shear wave elastography (pSWE) and two-dimensional shear wave elastography (2D-SWE) have shown that these techniques are all feasible and accurate in children for the evaluation of liver fibrosis due to several etiologies. However, for some specific pediatric pathologies, such as biliary atresia, the evidence is still limited. As shown in adults, inflammation is a confounding factor when assessing fibrosis severity and care should be taken when interpreting the results. Due to the scarce comparative data between serological tests and elastography techniques in children, a definite conclusion regarding which is the best cannot be drawn. Neither non-invasive elastographic techniques nor laboratory scores allow determination of the presence and the degree of inflammation, necrosis, iron or copper deposits. Full article
(This article belongs to the Special Issue Ultrasound Elastography)
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