| Prevention of post-focal thermal damage by formation of bubbles at the focus during high intensity focused ultrasound therapy. | |
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MedLine Citation:
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PMID: 18975674 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Safety concerns exist for potential thermal damage at tissue-air or tissue-bone interfaces located in the post-focal region during high intensity focused ultrasound (HIFU) treatments. We tested the feasibility of reducing thermal energy deposited at the post-focal tissue-air interfaces by producing bubbles (due to acoustic cavitation and/or boiling) at the HIFU focus. HIFU (in-situ intensities of 460-3500 W/cm2, frequencies of 3.2-5.5 MHz) was applied for 30 s to produce lesions (in turkey breast in-vitro (n = 37), and rabbit liver (n = 4) and thigh muscle in-vivo (n = 11)). Tissue temperature was measured at the tissue-air interface using a thermal (infrared) camera. Ultrasound imaging was used to detect bubbles at the HIFU focus, appearing as a hyperechoic region. In-vitro results showed that when no bubbles were present at the focus (at lower intensities of 460-850 W/cm2), the temperature at the interface increased continuously, up to 7.3 +/- 4.0 degrees C above the baseline by the end of treatment. When bubbles formed immediately after the start of HIFU treatment (at the high intensity of 3360 W/cm2), the temperature increased briefly for 3.5 s to 7.4 +/- 3.6 degrees C above the baseline temperature and then decreased to 4.0 +/- 1.4 degrees C above the baseline by the end of treatment. Similar results were obtained in in-vivo experiments with the temperature increases (above the baseline temperature) at the muscle-air and liver-air interfaces at the end of the high intensity treatment lower by 7.1 degrees C and 6.0 degrees C, respectively, as compared to the low intensity treatment. Thermal effects of HIFU at post-focal tissue-air interfaces, such as in bowels, could result in clinically significant increases in temperature. Bubble formation at the HIFU focus may provide a method for shielding the post-focal region from potential thermal damage. |
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Authors:
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Vesna Zderic; Jessica Foley; Wenbo Luo; Shahram Vaezy |
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Publication Detail:
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Type: Journal Article; Research Support, N.I.H., Extramural; Research Support, U.S. Gov't, Non-P.H.S. |
Journal Detail:
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Title: Medical physics Volume: 35 ISSN: 0094-2405 ISO Abbreviation: Med Phys Publication Date: 2008 Oct |
Date Detail:
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Created Date: 2008-11-03 Completed Date: 2008-12-09 Revised Date: 2009-11-18 |
Medline Journal Info:
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Nlm Unique ID: 0425746 Medline TA: Med Phys Country: United States |
Other Details:
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Languages: eng Pagination: 4292-9 Citation Subset: IM |
Affiliation:
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Department of Electrical and Computer Engineering, The George Washington University, Washington, DC 20052, USA. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Animals Breast / physiopathology, radiation effects* Burns / etiology*, prevention & control* Dose-Response Relationship, Radiation Gases Humans Radiation Dosage Radiation Injuries / etiology*, prevention & control* Turkeys Ultrasonic Therapy / adverse effects*, methods* |
| Grant Support | |
ID/Acronym/Agency:
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R01 EB00292/EB/NIBIB NIH HHS |
| Chemical | |
Reg. No./Substance:
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0/Gases |
| Comments/Corrections | |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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