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High-intensity focused ultrasound therapy: an overview for radiologists.

Kim YS, Rhim H, Choi MJ, Lim HK, Choi D - Korean J Radiol (2008 Jul-Aug)

Bottom Line: This completely non-invasive technology has great potential for tumor ablation as well as hemostasis, thrombolysis and targeted drug/gene delivery.However, the application of this technology still has many drawbacks.It is expected that current obstacles to implementation will be resolved in the near future.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.

ABSTRACT
High-intensity focused ultrasound therapy is a novel, emerging, therapeutic modality that uses ultrasound waves, propagated through tissue media, as carriers of energy. This completely non-invasive technology has great potential for tumor ablation as well as hemostasis, thrombolysis and targeted drug/gene delivery. However, the application of this technology still has many drawbacks. It is expected that current obstacles to implementation will be resolved in the near future. In this review, we provide an overview of high-intensity focused ultrasound therapy from the basic physics to recent clinical studies with an interventional radiologist's perspective for the purpose of improving the general understanding of this cutting-edge technology as well as speculating on future developments.

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Related in: MedlinePlus

Relationships between sound pressure, power, energy, and intensity. Sonic intensity, defined as energy passing through unit area within unit time, is derived from plane wave. As seen in equation, intensity is proportional to square of acoustic pressure and is also function of property of medium (density and speed of sound) through which waves are propagated.
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Figure 3: Relationships between sound pressure, power, energy, and intensity. Sonic intensity, defined as energy passing through unit area within unit time, is derived from plane wave. As seen in equation, intensity is proportional to square of acoustic pressure and is also function of property of medium (density and speed of sound) through which waves are propagated.

Mentions: Sonic intensity (SI) can be defined as a time-average rate of sonic energy-flow through a unit area (SI unit: W/cm2). The sonic intensity is proportional to sonic pressure square and has a positive correlation with the power and energy of sound (10). This implies that the higher the sonic pressure or intensity is, the larger the energy accumulation at the target area is (Fig. 3). Sonic intensity varies with space and time, and it is usually expressed as peak or average intensity, and both quantities can refer to either a spatial or temporal dimension (e.g. ISP = spatial peak intensity, ISATA = spatial average, temporal average intensity) (11, 12). In general, tissue-heating by US absorption is best predicted by the average intensity and the activity of acoustic cavitation by peak intensity (12). High-intensity US generally refers to US with an intensity (ISATA) higher than 5 W/cm2. This type of US can transfer enough energy to cause coagulation necrosis of tissue and is usually used for ultrasonic surgery. By contrast, low-intensity US (ISATA = 0.125-3 W/cm2) causes non-destructive heating, therefore, it stimulates or accelerates normal physiological responses to an injury. This range of US is usually used for physiotherapy (13).


High-intensity focused ultrasound therapy: an overview for radiologists.

Kim YS, Rhim H, Choi MJ, Lim HK, Choi D - Korean J Radiol (2008 Jul-Aug)

Relationships between sound pressure, power, energy, and intensity. Sonic intensity, defined as energy passing through unit area within unit time, is derived from plane wave. As seen in equation, intensity is proportional to square of acoustic pressure and is also function of property of medium (density and speed of sound) through which waves are propagated.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2627265&req=5

Figure 3: Relationships between sound pressure, power, energy, and intensity. Sonic intensity, defined as energy passing through unit area within unit time, is derived from plane wave. As seen in equation, intensity is proportional to square of acoustic pressure and is also function of property of medium (density and speed of sound) through which waves are propagated.
Mentions: Sonic intensity (SI) can be defined as a time-average rate of sonic energy-flow through a unit area (SI unit: W/cm2). The sonic intensity is proportional to sonic pressure square and has a positive correlation with the power and energy of sound (10). This implies that the higher the sonic pressure or intensity is, the larger the energy accumulation at the target area is (Fig. 3). Sonic intensity varies with space and time, and it is usually expressed as peak or average intensity, and both quantities can refer to either a spatial or temporal dimension (e.g. ISP = spatial peak intensity, ISATA = spatial average, temporal average intensity) (11, 12). In general, tissue-heating by US absorption is best predicted by the average intensity and the activity of acoustic cavitation by peak intensity (12). High-intensity US generally refers to US with an intensity (ISATA) higher than 5 W/cm2. This type of US can transfer enough energy to cause coagulation necrosis of tissue and is usually used for ultrasonic surgery. By contrast, low-intensity US (ISATA = 0.125-3 W/cm2) causes non-destructive heating, therefore, it stimulates or accelerates normal physiological responses to an injury. This range of US is usually used for physiotherapy (13).

Bottom Line: This completely non-invasive technology has great potential for tumor ablation as well as hemostasis, thrombolysis and targeted drug/gene delivery.However, the application of this technology still has many drawbacks.It is expected that current obstacles to implementation will be resolved in the near future.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.

ABSTRACT
High-intensity focused ultrasound therapy is a novel, emerging, therapeutic modality that uses ultrasound waves, propagated through tissue media, as carriers of energy. This completely non-invasive technology has great potential for tumor ablation as well as hemostasis, thrombolysis and targeted drug/gene delivery. However, the application of this technology still has many drawbacks. It is expected that current obstacles to implementation will be resolved in the near future. In this review, we provide an overview of high-intensity focused ultrasound therapy from the basic physics to recent clinical studies with an interventional radiologist's perspective for the purpose of improving the general understanding of this cutting-edge technology as well as speculating on future developments.

Show MeSH
Related in: MedlinePlus