Strain ultrasound elastography for liver diseases
Authors: Quan-Cheng Kan, Xin-Wu Cui, Jian-Min Chang, Christoph F. Dietrich
Journal: Journal of Hepatology (2015)

New imaging techniques for liver diseasesJournal of HepatologyVol. 62Issue 3PreviewNewly developed or advanced methods of ultrasonography and MR imaging provide combined anatomical and quantitative functional information about diffuse and focal liver diseases. Ultrasound elastography has a central role for staging liver fibrosis and an increasing role in grading portal hypertension; dynamic contrast-enhanced ultrasonography may improve tumor characterization. In clinical practice, MR imaging examinations currently include diffusion-weighted and dynamic MR imaging, enhanced with extracellular or hepatobiliary contrast agents. Full-Text PDF Open AccessReply to: "Strain ultrasound elastography for liver diseases"Journal of HepatologyVol. 63Issue 2PreviewWe thank Dr. Cui for his comment about the use of ultrasound strain elastography to assess liver disease. The aim of our review was not to perform a detailed analysis of all variants of ultrasound and MR imaging methods in assessing liver disease, but to discuss the value of new quantitative imaging methods, including ultrasound and MR elastography [1]. Full-Text PDF Open Access In a review published in a recent issue [[1]Van Beers B.E. Daire J.L. Garteiser P. New imaging techniques for liver diseases.J Hepatol. 2015; 62: 690-700Abstract Full Text Full Text PDF PubMed Scopus (83) Google Scholar], Van Beers et al. described the new ultrasonography and magnetic resonance imaging (MRI) techniques for the evaluation of diffuse and focal liver diseases. Regarding the section of ultrasound elastography, however, the authors failed to include strain elastography (SE), which is also one of the important elastography techniques for liver disease [2Cosgrove D. Piscaglia F. Bamber J. Bojunga J. Correas J.M. Gilja O.H. et al.EFSUMB guidelines and recommendations on the clinical use of ultrasound elastography. Part 2: Clinical applications.Ultraschall Med. 2013; 34: 238-253Crossref PubMed Scopus (742) Google Scholar, 3Kudo M. Shiina T. Moriyasu F. Lijima H. Tateishi R. Yada N. et al.JSUM ultrasound elastography practice guidelines: liver.J Med Ultrason. 2013; 40: 325-357Crossref PubMed Scopus (70) Google Scholar, 4Sporea I. Bota S. Saftoiu A. Sirli R. Gradinaru-Tascau O. Popescu A. et al.Romanian national guidelines and practical recommendations on liver elastography.Med Ultrason. 2014; 16: 123-138Crossref PubMed Scopus (30) Google Scholar]. Unlike shear wave based elastography, SE measures the strain response of tissue to stress such as manual compression or cardiovascular pulsation. Since soft tissue can be more easily compressed than hard tissue, the strain response can reflect the tissue stiffness, which is displayed on ultrasonography as a colour map overlaid to the grey scale image. Both qualitative and (semi-)quantitative methods have been developed in SE to analyze the tissue elasticity. The former analyses the colour distribution (pattern) within a region of interest (ROI), while the latter is performed either with strain histogram (SH) which computes the strain values of elemental areas inside a ROI or with strain ratio (SR) which measures the relative strain between two areas inside a ROI [[5]Cui X.W. Friedrich-Rust M. De Molo C. Ignee A. Schreiber-Dietrich D. Dietrich C.F. Liver elastography, comments on EFSUMB elastography guidelines 2013.World J Gastroenterol. 2013; 19: 6329-6347Crossref PubMed Scopus (41) Google Scholar]. Liver fibrosis is shown as uneven, patchy colour distribution on SE since the hardness of hepatic tissue is irregular, and the areas of low strain increase with the progression of liver fibrosis [[3]Kudo M. Shiina T. Moriyasu F. Lijima H. Tateishi R. Yada N. et al.JSUM ultrasound elastography practice guidelines: liver.J Med Ultrason. 2013; 40: 325-357Crossref PubMed Scopus (70) Google Scholar]. SE with quantitative methods has also been studied for assessing liver fibrosis. For patients with chronic virus hepatitis C, there is a significant correlation between the histological fibrosis stage and the SR, which is either the ratio of intercostal muscle/liver parenchyma (the median SR for F0, F1, F2, F3, F4 were 1.56, 1.36, 1.03, 0.62, and 0.45, respectively) [[6]Kanamoto M. Shimada M. Ikegami T. Uchiyama H. Imura S. Morine Y. et al.Real time elastography for noninvasive diagnosis of liver fibrosis.J Hepatobiliary Pancreat Surg. 2009; 16: 463-467Crossref PubMed Scopus (54) Google Scholar] or the ratio of small hepatic parenchyma/intrahepatic veins (the cut-off values of SR were 2.79 for F ⩾2, 3.25 for F ⩾3, and 3.93 for F = 4) [[7]Koizumi Y. Hirooka M. Kisaka Y. Konishi I. Abe M. Murakami H. et al.Liver fibrosis in patients with chronic hepatitis C: noninvasive diagnosis by means of real-time tissue elastography–establishment of the method for measurement.Radiology. 2011; 258: 610-617Crossref PubMed Scopus (124) Google Scholar]. When SH was used, the area under the receiver operating characteristic curves (AUROC) was 0.93 for F ⩾3 and 0.91 for F = 4 for the SH to predict fibrosis stage [[8]Morikawa H. Fukuda K. Kobayashi S. Fujii H. Iwai S. Enomoto M. et al.Real-time tissue elastography as a tool for the noninvasive assessment of liver stiffness in patients with chronic hepatitis C.J Gastroenterol. 2011; 46: 350-358Crossref PubMed Scopus (82) Google Scholar]. For patients with chronic virus hepatitis B, promising results were also reported. In a study using SH and quantitative parameters (elasticity index), the AUROCs for the diagnosis of F ⩾1, F ⩾2, F ⩾3, and F = 4 were 0.93, 0.92, 0.84, and 0.66, respectively [[9]Wang J. Guo L. Shi X. Pan W. Bai Y. Ai H. Real-time elastography with a novel quantitative technology for assessment of liver fibrosis in chronic hepatitis B.Eur J Radiol. 2012; 81: e31-e36Abstract Full Text Full Text PDF PubMed Scopus (72) Google Scholar]. A study compared the diagnostic performance of SE, transient elastography (TE) and acoustic radiation force impulse imaging (ARFI). Results showed that TE and ARFI performed slightly better than SE in predicting significant fibrosis (AUROC = 0.751, 0.897, and 0.815 for SE, TE, and ARFI, respectively), however, there were no significant differences among the three techniques in diagnosing cirrhosis (AUROC = 0.852, 0.922, and 0.934 for SE, TE, and ARFI, respectively) [[10]Colombo S. Buonocore M. Del Poggio A. Jamoletti C. Elia S. Mattiello M. et al.Head-to-head comparison of transient elastography (TE), real-time tissue elastography (RTE), and acoustic radiation force impulse (ARFI) imaging in the diagnosis of liver fibrosis.J Gastroenterol. 2012; 47: 461-469Crossref PubMed Scopus (86) Google Scholar]. The European and Romanian elastography guidelines suggest that further research on assessing liver fibrosis with SE are still needed to provide more evidence [2Cosgrove D. Piscaglia F. Bamber J. Bojunga J. Correas J.M. Gilja O.H. et al.EFSUMB guidelines and recommendations on the clinical use of ultrasound elastography. Part 2: Clinical applications.Ultraschall Med. 2013; 34: 238-253Crossref PubMed Scopus (742) Google Scholar, 4Sporea I. Bota S. Saftoiu A. Sirli R. Gradinaru-Tascau O. Popescu A. et al.Romanian national guidelines and practical recommendations on liver elastography.Med Ultrason. 2014; 16: 123-138Crossref PubMed Scopus (30) Google Scholar], but the Japanese elastography guidelines state that SE accurately measures liver fibrosis [[3]Kudo M. Shiina T. Moriyasu F. Lijima H. Tateishi R. Yada N. et al.JSUM ultrasound elastography practice guidelines: liver.J Med Ultrason. 2013; 40: 325-357Crossref PubMed Scopus (70) Google Scholar]. Considering that SE has been broadly discussed as one of the main elastography techniques besides TE, ARFI and supersonic shear imaging for assessing liver stiffness in the international guidelines [2Cosgrove D. Piscaglia F. Bamber J. Bojunga J. Correas J.M. Gilja O.H. et al.EFSUMB guidelines and recommendations on the clinical use of ultrasound elastography. Part 2: Clinical applications.Ultraschall Med. 2013; 34: 238-253Crossref PubMed Scopus (742) Google Scholar, 3Kudo M. Shiina T. Moriyasu F. Lijima H. Tateishi R. Yada N. et al.JSUM ultrasound elastography practice guidelines: liver.J Med Ultrason. 2013; 40: 325-357Crossref PubMed Scopus (70) Google Scholar, 4Sporea I. Bota S. Saftoiu A. Sirli R. Gradinaru-Tascau O. Popescu A. et al.Romanian national guidelines and practical recommendations on liver elastography.Med Ultrason. 2014; 16: 123-138Crossref PubMed Scopus (30) Google Scholar], we conclude that SE should not be excluded in this comprehensive review. We declared that we do not have anything to disclose regarding funding or conflict of interest with respect to this manuscript.