Article

Real-time sonoelastography of hepatic thermal lesions in a swine model

Department of Biomedical Engineering, University of Rochester, Rochester New York 14627, USA.
Medical Physics (Impact Factor: 3.01). 10/2008; 35(9):4132-41. DOI: 10.1118/1.2968939
Source: PubMed

ABSTRACT Sonoelastography has been developed as an ultrasound-based elasticity imaging technique. In this technique, external vibration is induced into the target tissue. In general, tissue stiffness is inversely proportional to the amplitude of tissue vibration. Imaging tissue vibration will provide the elasticity distribution in the target region. This study investigated the feasibility of using real-time sonoelastography to detect and estimate the volume of thermal lesions in porcine livers in vivo. A total of 32 thermal lesions with volumes ranging from 0.2 to 5.3 cm3 were created using radiofrequency ablation (RFA) or high-intensity focused ultrasound (HIFU) technique. Lesions were imaged using sonoelastography and coregistered B-mode ultrasound. Volumes were reconstructed from a sequence of two-dimensional scans. The comparison of sonoelastographic measurements and pathology findings showed good correlation with respect to the area of the lesions (r2 = 0.8823 for RFA lesions, r2 = 0.9543 for HIFU lesions). In addition, good correspondence was found between three-dimensional sonoelastography and gross pathology (3.6% underestimate), demonstrating the feasibility of sonoelastography for volume estimation of thermal lesions. These results support that sonoelastography outperforms conventional B-mode ultrasound and could potentially be used for assessment of thermal therapies.

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    • "Elastography is a form of virtual palpation used to differentiate tissue with differing stiffness and has been used to image lesions that cannot be detected with manual palpation alone, such as stiffer masses in the liver. For example, sonoelastography has delineated stiff thermal ablations ex vivo (Zhang et al., 2008). Strain imaging has been used to demarcate radiofrequency ablations ex vivo and in vivo, using the ablation electrode as the compression device (Bharat et al., 2008; Rubert et al., 2010; Liu et al., 2006). "
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    • "A variety of parameters derived from ultrasound imaging signals beyond the conventional grayscale representation of the logarithmically-compressed envelope signal have been proposed for improving imaging lesion formation. For example, calibrated spectral parameters of fundamental and harmonic frequencies (Lizzi et al. 1997; Silverman et al. 2006), attenuation and/or ultrasound backscatter (Anand and Kaczkowski 2004; Ribault et al. 1998; Zhang et al. 2009; Zhong et al. 2007), temperature (Amini et al. 2005; Arthur et al. 2010; Liu and Ebbini 2010; Miller et al. 2002; Seip and Ebbini 1995; Straube and Arthur 1994), thermal diffusivity (Anand and Kaczkowski 2008), strain or stiffness (Eyerly et al. 2010; Fahey et al. 2005; Kallel et al. 1999; Lizzi et al. 2003; Maleke and Konofagou 2008; Shi et al. 1999; Souchon et al. 2005; Zhang et al. 2008), and echo-decorrelation (Mast et al. 2008), have been exploited. However, these methods can be subject to artifacts from tissue movement, problematic over the large range of temperature variations in HIFU ablation, and disrupted by cavity formation (Miller et al. 2002; Zheng and Vaezy 2010). "
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