3Shear wave elastography (SWE)
Ultrasound-based shear wave elastography is an imaging mode that enables an ultrasound platform to quantify tissue elasticity with or without an elasticity map, depending on its technical implementation. In all commercially available ultrasound systems, it uses the acoustic radiation force related to ultrasound focusing to generate shear waves in tissue. These mechanical shear waves then propagate orthogonally to the pushing ultrasound beam at a speed that can be assumed to be proportional to the square root of tissue Young’s Modulus, also known as tissue elasticity [(13;14)]. Here we used ShearWave™ Elastography (SWE™) that was implemented by SuperSonic Imagine on the Aixplorer® ultrasound imaging system. This ultrasound platform is capable of reaching an acquisition frame rate that is suitable with the supersonic shear imaging (SSI) technique [(15)]. This technical implementation of shear wave elastography enables the operator to get a quantitative mapping of tissue elasticity in real-time, at an imaging frame rate of a few images per second. Thanks to the supersonic shear imaging technique and the ultrafast acquisition speed (several thousands of images per second), heating of the probe is avoided and acoustic energy stays within the limits used in routine so no cool-down time is required, operators are getting a real-time feedback like with any other ultrasound imaging mode, thus allowing them to adjust their scanning technique as required, and many trade-offs can be saved between the overall image quality, the size and depth of the SWE-Box, the spatial and temporal resolutions in SWE™, and the maximum elasticity values measured.
5Review of the literature (3D SWE)
In the field of breast lesions and breast cancer imaging, 3D SWE™ has been reported to provide equivalent results as compared to 2D SWE™ for the characterization of known breast masses [(16)]. Using SWE™ to help in characterizing 144 breast masses with ultrasound, Lee et al reported an increase in specificity of breast ultrasound from 30% up to 64% with 3D SWE, without any significant change in sensitivity. In another study on 146 patients with 163 breast masses, it was demonstrated that the inter-observer agreement on breast cancer risk assessment with ultrasound was significantly increased from kappa=0.38 to kappa=0.73 with the addition of 3D-SWE qualitative assessment [(17)]. Still in the breast arena, Athanasiou et al reported recently that tumor volume assessment with 3D ultrasound and 3D SWE was highly concordant with dynamic contrast-enhanced MRI tumour volume. In this feasibility study on 10 patients, 3D SWE demonstrated a clear value as a potential indicator of breast cancer response to neoadjuvant chemotherapy, because it could assess at the same time the changes in tumour volume and stiffness [(18)].
1. Dietrich CF. 3D abdominal sonography. Electromedica 2001; 69(2):23-29.
2. Dietrich CF. [3D real time contrast enhanced ultrasonography,a new technique]. Rofo 2002; 174(2):160-163.
3. Hocke M, Dietrich CF. New technology--combined use of 3D contrast enhanced endoscopic ultrasound techniques. Ultraschall Med 2011; 32(3):317-318.
4. Skovronsky DM, Oberholtzer JC. Pathologic classification of peripheral nerve tumors. Neurosurg Clin N Am 2004; 15(2):157-166.
5. Chiorean L, Barr RG, Braden B, Jenssen C, Cui XW, Hocke M et al. Transcutaneous Ultrasound: Elastographic Lymph Node Evaluation. Current Clinical Applications and Literature Review. Ultrasound Med Biol 2016; 42(1):16-30.
6. Cui XW, Jenssen C, Saftoiu A, Ignee A, Dietrich CF. New ultrasound techniques for lymph node evaluation. World J Gastroenterol 2013; 19(30):4850-4860.
7. Cui XW, Ignee A, Bachmann NM, Schreiber-Dietrich D, De Molo C, Pirri C et al. Contrast enhanced ultrasound of sentinel lymph nodes. J Ultrason 2013; 13:73-81.
8. Cui XW, Hocke M, Jenssen C, Ignee A, Klein S, Schreiber-Dietrich D et al. Conventional ultrasound for lymph node evaluation, update 2013. Z Gastroenterol 2014; 52(2):212-221.
9. Cui XW, Chang JM, Kan QC, Chiorean L, Ignee A, Dietrich CF. Endoscopic ultrasound elastography: Current status and future perspectives. World J Gastroenterol 2015; 21(47):13212-13224.
10. Dietrich CF, Annema JT, Clementsen P, Cui XW, Borst MM, Jenssen C. Ultrasound techniques in the evaluation of the mediastinum, part I: endoscopic ultrasound (EUS), endobronchial ultrasound (EBUS) and transcutaneous mediastinal ultrasound (TMUS), introduction into ultrasound techniques. J Thorac Dis 2015; 7(9):E311-E325.
11. Dietrich CF, Jenssen C, Arcidiacono PG, Cui XW, Giovannini M, Hocke M et al. Endoscopic ultrasound: Elastographic lymph node evaluation. Endosc Ultrasound 2015; 4(3):176-190.
12. Dietrich CF, Annema JT, Clementsen P, Cui XW, Borst MM, Jenssen C. Ultrasound techniques in the evaluation of the mediastinum, part I: endoscopic ultrasound (EUS), endobronchial ultrasound (EBUS) and transcutaneous mediastinal ultrasound (TMUS), introduction into ultrasound techniques. J Thorac Dis 2015; 7(9):E311-E325.
13. Bamber J, Cosgrove D, Dietrich CF, Fromageau J, Bojunga J, Calliada F et al. EFSUMB guidelines and recommendations on the clinical use of ultrasound elastography. Part 1: Basic principles and technology. Ultraschall Med 2013; 34(2):169-184.
14. Cosgrove D, Piscaglia F, Bamber J, Bojunga J, Correas JM, Gilja OH et al. EFSUMB Guidelines and Recommendations on the Clinical Use of Ultrasound Elastography.Part 2: Clinical Applications. Ultraschall Med 2013; 34(3):238-253.
15. Bercoff J, Tanter M, Fink M. Supersonic shear imaging: a new technique for soft tissue elasticity mapping. IEEE Trans Ultrason Ferroelectr Freq Control 2004; 51(4):396-409.
16. Lee SH, Chang JM, Kim WH, Bae MS, Cho N, Yi A et al. Differentiation of benign from malignant solid breast masses: comparison of two-dimensional and three-dimensional shear-wave elastography. Eur Radiol 2013; 23(4):1015-1026.
17. Youk JH, Gweon HM, Son EJ, Chung J, Kim JA, Kim EK. Three-dimensional shear-wave elastography for differentiating benign and malignant breast lesions: comparison with two-dimensional shear-wave elastography. Eur Radiol 2013; 23(6):1519-1527.
18. Athanasiou A, Latorre-Ossa H, Criton A, Tardivon A, Gennisson JL, Tanter M. Feasibility of Imaging and Treatment Monitoring of Breast Lesions with Three-Dimensional Shear Wave Elastography. Ultraschall Med 2015.