Acoustic Droplet Vaporization for Enhancement of Thermal Ablation by High Intensity Focused Ultrasound

作者：Zhang Man^*; Fabiilli Mario L; Haworth Kevin J; Padilla Frederic; Swanson Scott D; Kripfgans Oliver D; Carson Paul L; Fowlkes Jeffrey Brian

来源：Academic Radiology, 2011, 18(9): 1123-1132.

DOI：10.1016/j.acra.2011.04.012

• Minimally invasive therapy
• microbubble
• thermal lesion size
• ultrasound
• in vivo

Rationale and Objectives: Acoustic droplet vaporization (ADV) shows promise for spatial control and acceleration of thermal lesion production. The investigators hypothesized that microbubbles generated by ADV could enhance high-intensity focused ultrasound (HIFU) thermal ablation by controlling and increasing local energy absorption.
Materials and Methods: Thermal lesions were produced in tissue-mimicking phantoms using focused ultrasound (1.44 MHz) with a focal intensity of 4000W . cm(-2) in degassed water at 37 degrees C. The average lesion volume was measured by visible change in optical opacity and by T2-weighted magnetic resonance imaging. In addition, in vivo HIFU lesions were generated in a canine liver before and after an intravenous injection of droplets with a similar acoustic setup.
Results: Thermal lesions were sevenfold larger in phantoms containing droplets (3 x 10(5) droplets/mL) compared to phantoms without droplets. The mean lesion volume with a 2-second HIFU exposure in droplet-containing phantoms was comparable to that made by a 5-second exposure in phantoms without droplets. In the in vivo study, the average lesion volumes without and with droplets were 0.017 +/- 0.006 cm(3) (n = 4; 5-second exposure) and 0.265 +/- 0.005 cm(3) (n = 3; 5-second exposure), respectively, a factor of 15 difference. The shape of ADV bubbles imaged with B-mode ultrasound was very similar to the actual lesion shape as measured optically and by magnetic resonance imaging.
Conclusion: ADV bubbles may facilitate clinical HIFU ablation by reducing treatment time or requisite in situ total acoustic power and provide ultrasonic imaging feedback of the thermal therapy.

• 出版日期2011-9