Suitability of a tumour-mimicking material for the evaluation of high-intensity focused ultrasound ablation under magnetic resonance guidance

• Published in: Physics in medicine & biology 2013-04, Vol.58 (7), p.2163-2183
• Main Authors: Pichardo, S, Kivinen, J, Melodelima, D, Curiel, L
• Format: Article
• Language: English
• Subjects: Absorption; Animals; Cattle; focused ultrasound; High-Intensity Focused Ultrasound Ablation - instrumentation; imaging guidance; Liver; magnetic resonance guidance; Magnetic Resonance Imaging; Neoplasms - surgery; Phantoms, Imaging; Rabbits; Surgery, Computer-Assisted - instrumentation; Temperature; tumour mimic
• ISSN: 0031-9155; 1361-6560
• DOI: 10.1088/0031-9155/58/7/2163

This study tests the suitability of a tumour-mimic for targeting magnetic resonance (MR)-guided high-intensity focused ultrasound (HIFU). An agarose-based tumour-mimic was injected as a warm solution that polymerized in tissue. Thermal characteristics and acoustic absorption of the mimic were observed within the values reported for tissues. The relaxation times at 3T were 1679 ± 15 ms for T1 and 41 ± 1 ms for T2. The mimic was clearly visible on T1-weighted images. With lower contrast the tumour-mimic was visible on T2-weighted images, where it was possible to detect the ablated tissue surrounding the mimic after sonications. HIFU sonications were performed to induce thermal ablation on and around the mimic using a Sonalleve system (Philips). MR thermometry maps were performed during HIFU. The average temperature when the sonication was done at the tumour-mimic was 67.6 ± 8.0 °C in vitro and 67.6 ± 5.0 °C in vivo. The average temperature for sonications at tissues was 68.4 ± 8.7 °C in vitro (liver) and 66.0 ± 2.6 °C in vivo (muscle), with no significant difference between tissue and tumour-mimic (p > 0.05). The tumour-mimic behaviour when using MR-guided HIFU was similar to tissues, showing that this mimic can be used as an alternative to tumour models for validating MR-guided HIFU devices targeting.