Intra-operative ultrasound hand-held strain imaging for the visualization of ablations produced in the liver with a toroidal HIFU transducer: first in vivo results

• Published in: Physics in medicine & biology 2010-06, Vol.55 (11), p.3131-3144
• Main Authors: Chenot, J, Melodelima, D, N'Djin, W A, Souchon, Rémi, Rivoire, M, Chapelon, J Y
• Format: Article
• Language: English
• Subjects: Acoustics; Algorithms; Animals; Bioengineering; Computer Simulation; Computers; Elasticity Imaging Techniques - methods; Engineering Sciences; Equipment Design; High-Intensity Focused Ultrasound Ablation - methods; Life Sciences; Liver - pathology; Mechanics; Physics; Swine; Time Factors; Transducers; Treatment Outcome; Ultrasonic Therapy - methods; Ultrasonography - methods
• ISSN: 0031-9155; 1361-6560
• DOI: 10.1088/0031-9155/55/11/010

The use of hand-held ultrasound strain imaging for the intra-operative real-time visualization of HIFU (high-intensity focused ultrasound) ablations produced in the liver by a toroidal transducer was investigated. A linear 12 MHz ultrasound imaging probe was used to obtain radiofrequency signals. Using a fast cross-correlation algorithm, strain images were calculated and displayed at 60 frames s(-1), allowing the use of hand-held strain imaging intra-operatively. Fourteen HIFU lesions were produced in four pigs. Intra-operative strain imaging of HIFU ablations in the liver was feasible owing to the high frame rate. The correlation between dimensions measured on gross pathology and dimensions measured on B-mode images and on strain images were R = 0.72 and R = 0.94 respectively. The contrast between ablated and non-ablated tissue was significantly higher (p < 0.05) in the strain images (22 dB) than in the B-mode images (9 dB). Strain images allowed equivalent or improved definition of ablated regions when compared with B-mode images. Real-time intra-operative hand-held strain imaging seems to be a promising complement to conventional B-mode imaging for the guidance of HIFU ablations produced in the liver during an open procedure. These results support that hand-held strain imaging outperforms conventional B-mode ultrasound and could potentially be used for the assessment of thermal therapies.