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Интеллектуальная Система Тематического Исследования НАукометрических данных |
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Optimization of beam-steering trajectories for generating volumetric boiling histotripsy lesions in tissue using a multi-element clinical arrayтезисы доклада
- Авторы: Farr N., Partanen A., Kreider W., Khokhlova T.D., Y-N Wang, Maxwell A., Sapozhnikov O.A., Bailey M.R., Khokhlova V.A.
- Сборник: Program of the 15th International Symposium for Therapeutic Ultrasound
- Тезисы
- Год издания: 2015
- Место издания: Utrecht, Netherlands
- Первая страница: 217
- Последняя страница: 218
- Аннотация: Clinical protocols of HIFU systems that utilize electronic steering of multi-element phased arrays are currently optimized for thermal ablation treatments. Concentric-circle trajectories, starting from a central location, are used to heat a cylindrically shaped volume such that the lesion size is enhanced by heat diffusion from the sonicated volume. With this strategy, the temperature in the treated tissue is higher close to the center of the cylinder. Recently, these same circular trajectories were used to create mechanically fractionated lesions in ex vivo bovine liver using an approach termed boiling histotripsy. In these experiments, nonuniform temperature rises and thus stronger thermal effects were observed in the centers of volumetric lesions. The goal of this study was to develop and test a different geometry of beam-steering locations to keep temperatures more uniform over the entire treated region, thereby minimizing thermal denaturation effects in volumetric lesions and heat diffusion in the prefocal axial direction. A boiling histotripsy pulsing scheme was combined with the electronic steering of a multi-element 1.2 MHz HIFU phased array (Sonalleve, Philips Healthcare, Vantaa, Finland) to generate lesions in ex vivo bovine tissue. Sonications were performed with 10 ms-long pulses, 25 pulses per sonication point, pulse repetition frequency (PRF) of 3 Hz, and 250 W of acoustic power which corresponded to focal waveforms with in situ shock amplitudes of about 65 MPa. Two different spatial patterns of focal locations were tested using electronic steering: concentric circles that fill a maximum diameter of 8 mm, and lines that fill a square 8 mm on each side (see Fig. 1). Three layers of such patterns were generated at tissue depths of 2.5, 2, and 1.5 cm to form volumetric lesions. In both patterns, the spacing between each line or circle was 2mm; adjacent lesions were separated by 1.6 mm along each circular arc or by 2mm along each line. For both patterns, each focal location was sonicated with one pulse, proceeding sequentially to adjacent locations; after each location was sonicated, the sequence of all locations was repeated 25 times. Cylindrical and cubical lesion volumes were created, with real-time MR monitoring of temperature distributions and maximum temperature rises within the treatment volumes. After treatments were completed, final lesions were characterized on MR images, gross examination, and histology. From real-time temperature maps, maximum temperature rises in cubical lesions were lower than in cylindrical lesions by 5 degrees. These lower temperatures were also correlated with histotripsy lesions exhibiting less thermal protein denaturation as evaluated by gross examination and histology. It was shown that a clinical HIFU system is capable of producing different shapes of volumetric lesions of mechanically fractionated tissue using a boiling histotripsy method in conjunction with electronic steering of the focal beam. The shape of each final lesion corresponded very well to the aggregate geometry of the targeted focal locations. It was shown that thermal effects in volumetric lesions can be controlled by optimizing the geometry and time sequences of sonication trajectories. Work supported by NIH EB7643, K01 EB 015745, T32 DK007779, and RSF grant 14-12-00974.
- Добавил в систему: Хохлова Вера Александровна
Прикрепленные файлы
| № | Имя | Описание | Имя файла | Размер | Добавлен |
|---|---|---|---|---|---|
| 1. | ISTUMRI.pdf | ISTUMRI.pdf | 566,0 КБ | 9 декабря 2015 [va.khokhlova] |