Effect of split-focus approach on producing larger coagulation in swine liver

Kazuaki Sasaki, Takashi Azuma, Ken Ichi Kawabata, Minoru Shimoda, Ei Ichi Kokue, Shin Ichiro Umemura

Research output: Contribution to journalArticlepeer-review

33 Citations (Scopus)


The split-focus approach has the potential to substantially improve the throughput of coagulation high-intensity focused ultrasound (HIFU) treatment. A prototype split-focus transducer with four elements at 4.25 MHz, combined with a small imaging probe at 6.5 MHz, was constructed for transrectal treatment of a prostate. Computer simulation predicted that 1.57 times larger acoustic power than a single-spot focus was required for a split focus to heat the tissue up to the same peak temperature at 4 s from the start of insonation. When the peak temperature was 100°C, the tissue volume above 70°C was predicted to be 2.3 times larger for a split focus. Swine liver lobes were intraoperatively insonated with the split-focus transducer for 4 s. A lesion of coagulation necrosis 3 to 4 times larger in volume than with a single-spot focus was formed with a split focus at the same acoustic power ratio as described above. Furthermore, a lesion about 2 times larger in volume was formed when compared at the same acoustic power. These results show the great advantage of a split-focus approach over a conventional single-spot focus in coagulation treatment.

Original languageEnglish
Pages (from-to)591-599
Number of pages9
JournalUltrasound in Medicine and Biology
Issue number4
Publication statusPublished - 2003 Apr 1


  • Coagulation
  • Focused ultrasound
  • Goettingen miniature pig
  • HIFU
  • Single-spot focus
  • Split focus
  • Swine liver
  • Temperature
  • Therapy

ASJC Scopus subject areas

  • Biophysics
  • Radiological and Ultrasound Technology
  • Acoustics and Ultrasonics


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