In vitro and in vivo evaluations of increased effective beam width for heat deposition using a split focus high intensity ultrasound (HIFU) transducer

Pretesh R. Patel, Alfred Luk, Amirk Durrani, Sergio Dromi, Julian Cuesta, Mary Angstadt, Matthew R. Dreher, Bradford J. Wood, Victor Frenkel

Research output: Contribution to journalArticlepeer-review

Abstract

Purpose: To develop a novel and efficient, in vitro method for characterizing temporal and spatial heat generation of focused ultrasound exposures, and evaluate this method to compare a split focus and conventional single focus high intensity focused ultrasound transducer. Materials and methods: A HIFU tissue-mimicking phantom was validated by comparing respective temperature elevations generated in the phantoms and in murine tumors in vivo. The phantom was then used in combination with IR thermography to spatially and temporally characterize differences in low-level temperature elevation (e.g. 3-5°C) produced by a single focus and split focus HIFU transducer, where the latter produces four simultaneous foci. In vivo experiments with heat sensitive liposomes containing doxorubicin were then carried out to determine if the larger beam width of the split focus transducer, compared to the single focus, could increase overall deployment of the drug from the liposome. Results: Temperature elevations generated in the HIFU phantom were not found to be different from those measured in vivo when compensating for disparities in attenuation coefficient and specific heat, and between the two transducers by increasing the energy deposition. Exposures with the split focus transducer provided significant increases in the area treated compared to the single focus, which then translated to significant increases in drug deposition in vivo. Conclusions: Preliminary evidence was provided indicating the potential for using this novel technique for characterizing hyperthermia produced by focused ultrasound devices. Further development will be required for its suitability for correlating in vitro and in vivo outcomes.

Original languageEnglish (US)
Pages (from-to)537-549
Number of pages13
JournalInternational Journal of Hyperthermia
Volume24
Issue number7
DOIs
StatePublished - 2008
Externally publishedYes

Keywords

  • High intensity focused ultrasound
  • Image guided therapy
  • Infrared imaging
  • Low temperature sensitive liposomes
  • Single focus and split focus transducer

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)
  • Cancer Research

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