Electrode displacement strain imaging of thermally-ablated liver tissue in an in vivo animal model

• Published in: Medical physics (Lancaster) 2010-03, Vol.37 (3), p.1075-1082
• Main Authors: Rubert, N., Bharat, S., DeWall, R. J., Andreano, A., Brace, C., Jiang, J., Sampson, L., Varghese, T.
• Format: Article
• Language: English
• Subjects: ablation; Animals; biomechanics; biomedical electrodes; biomedical ultrasonics; Cancer; Catheter Ablation - instrumentation; Catheter Ablation - methods; elasticity; elasticity imaging; Elasticity Imaging Techniques - methods; elastography; electrode displacement; Electrodes; heat treatment; Hepatectomy - methods; Humans; image segmentation; liver; Liver - diagnostic imaging; Liver - surgery; Mechanical and electrical properties of tissues and organs; medical image processing; Medical image segmentation; Medical imaging; microwave ablation; radiation therapy; radiofrequency ablation; Reproducibility of Results; Segmentation; Sensitivity and Specificity; strain; Strain measurement; Surgery, Computer-Assisted - instrumentation; Surgery, Computer-Assisted - methods; Swine; Therapeutic applications; Thermal imaging; Tissue ablation; Tissues; tumours; Ultrasonography; Ultrasonography - methods; ultrasound; Ultrasound Physics
• ISSN: 0094-2405; 2473-4209; 0094-2405
• DOI: 10.1118/1.3301603

Purpose: Percutaneous thermal ablation is increasingly being used to destroy hepatic tumors in situ. The success of ablative techniques is highly dependent on adequate ablation zone monitoring, and ultrasound-based strain imaging could become a convenient and cost-effective means to delineate ablation zone boundaries. This study investigates in vivo electrode displacement-based strain imaging for monitoring hepatic ablation procedures that are difficult to perform with conventional elastography. Methods: In our method, minute displacements (less than a millimeter) are applied to the unconstrained end of the ablation electrode, resulting in localized tissue deformation within the ablation zone that provides the mechanical stimuli required for strain imaging. This article presents electrode displacement strain images of radiofrequency ablation zones created in porcine liverin vivo ( n = 13 ) . Results: Cross-sectional area measurements from strain images of these ablation zones were obtained using manual and automated segmentation. Area measurements from strain images were highly correlated with areas measured on histopathology images, quantitated using linear regression ( R = 0.894 , P < 0.001 and R = 0.828 , P < 0.001 , respectively). Conclusions: This study further demonstrates that electrode displacement elastography is capable of providing high-contrast images using widely available commercial ultrasound systems which may potentially be used to assess the extent of thermal ablation zones.