Ultrasound therapy applicators for controlled thermal modification of tissue

E. Clif Burdette, Carol Lichtenstiger, Laurie Rund, Mallika Keralapura, Chad Gossett, Randy Stahlhut, Paul Neubauer, Bruce Komadina, Emery Williams, Chris Alix, Tor Jensen, Lawrence Schook, Chris J. Diederich

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

Abstract

Heat therapy has long been used for treatments in dermatology and sports medicine. The use of laser, RF, microwave, and more recently, ultrasound treatment, for psoriasis, collagen reformation, and skin tightening has gained considerable interest over the past several years. Numerous studies and commercial devices have demonstrated the efficacy of these methods for treatment of skin disorders. Despite these promising results, current systems remain highly dependent on operator skill, and cannot effectively treat effectively because there is little or no control of the size, shape, and depth of the target zone. These limitations make it extremely difficult to obtain consistent treatment results. The purpose of this study was to determine the feasibility for using acoustic energy for controlled dose delivery sufficient to produce collagen modification for the treatment of skin tissue in the dermal and sub-dermal layers. We designed and evaluated a curvilinear focused ultrasound device for treating skin disorders such as psoriasis, stimulation of wound healing, tightening of skin through shrinkage of existing collagen and stimulation of new collagen formation, and skin cancer. Design parameters were examined using acoustic pattern simulations and thermal modeling. Acute studies were performed in 201 freshly-excised samples of young porcine underbelly skin tissue and 56 in-vivo treatment areas in 60- 80 kg pigs. These were treated with ultrasound (9-11MHz) focused in the deep dermis. Dose distribution was analyzed and gross pathology assessed. Tissue shrinkage was measured based on fiducial markers and video image registration and analyzed using NIH Image-J software. Comparisons were made between RF and focused ultrasound for five energy ranges. In each experimental series, therapeutic dose levels (60degC) were attained at 2-5mm depth. Localized collagen changes ranged from 1-3% for RF versus 8-15% for focused ultrasound. Therapeutic ultrasound applied at high frequencies can achieve temperatures and dose distributions which concentrate in a depth profile that coincides with the location of maximum structural collagen content in skin tissues. Using an appropriate transducer configuration produces coverage of significant lateral area, thus making this a practical approach for treatment of skin disorders.

Original languageEnglish (US)
Title of host publicationEnergy-Based Treatment of Tissue and Assessment VI
DOIs
StatePublished - 2011
EventEnergy-Based Treatment of Tissue and Assessment VI - San Francisco, CA, United States
Duration: Jan 23 2011Jan 24 2011

Publication series

NameProgress in Biomedical Optics and Imaging - Proceedings of SPIE
Volume7901
ISSN (Print)1605-7422

Other

OtherEnergy-Based Treatment of Tissue and Assessment VI
Country/TerritoryUnited States
CitySan Francisco, CA
Period1/23/111/24/11

Keywords

  • Blurred focus
  • Collagen
  • Conformal ultrasound therapy
  • Focused transducer
  • Skin disorders
  • Ultrasound

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Radiology Nuclear Medicine and imaging

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