Radiation force imaging for detection of irreversible ChangesCaused by high intensity focused ultrasound therapy

Takashi Azuma, Kazuaki Sasaki, Ken Ichi Kawabata, Shinichiro Umemura

Research output: Chapter in Book/Report/Conference proceedingConference contribution

3 Citations (Scopus)


Therapy monitoring based on echo-time-shift imaging during high intensity focused ultrasound (HIFU) treatment was described. The echo shift estimated by radio frequency (RF) correlation between adjacent frames is potentially useful for mapping coagulation and tissue temperature. B-mode images are also useful for real-time monitoring, but cannot show the denatured region formed below the boiling point. Echo-shift images are, however, can. They are affected by temperature-dependant changes in the speed of sound, by thermal expansion of tissues, and by tissue expansion caused by irreversibly denatured protein and the radiation force generated by HIFU. To separate the effect of radiation force from other thermal changes, we used a split-focus technique with which the peak of ultrasonic intensity can be shifted from the peak tissue temperature. Tissue expansion was mapped with a split HIFU beam with large separation in an in vitro experiment. With a narrow HIFU beam, in contrast, the effect of radiation force exceeded that of expansion and focal tissue displacement away from the transducer was observed Since the time course of tissue expansion did not follow that of the temperature change, it was suggested that echo-shift imaging could detect region in which coagulation occurred below the boiling temperature, which regions are could not be detected by B-mode imaging. Because tissue expansion could be also detected in an in vivo experiment, the detection of tissue expansion is useful for monitoring coagulation during thermal therapy.

Original languageEnglish
Title of host publication2005 IEEE Ultrasonics Symposium
Number of pages4
Publication statusPublished - 2005 Dec 1
Event2005 IEEE Ultrasonics Symposium - Rotterdam, Netherlands
Duration: 2005 Sep 182005 Sep 21

Publication series

NameProceedings - IEEE Ultrasonics Symposium
ISSN (Print)1051-0117


Other2005 IEEE Ultrasonics Symposium

ASJC Scopus subject areas

  • Engineering(all)


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