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. 2024 Nov 8;11(11):1126.
doi: 10.3390/bioengineering11111126.

Preliminary Examination of the Effects of Focused Ultrasound on Living Skin and Temperature at the Skin-Transducer Interface

Andrew A E D Bishay  1 , Andrew J Swenson  2 , Norman M Spivak  1   3 , Samantha Schafer  4 , Brendan P Bych  1   5 , Spencer D Gilles  1   6 , Christopher Dorobczynski  1   7 , Alexander S Korb  1 , Mark E Schafer  4 , Taylor P Kuhn  1 , Martin M Monti  1   3   8 , Alexander Bystritsky  1
Affiliations

Preliminary Examination of the Effects of Focused Ultrasound on Living Skin and Temperature at the Skin-Transducer Interface

Andrew A E D Bishay et al. Bioengineering (Basel). .

Abstract

Transcranial Focused Ultrasound Stimulation (tFUS) is a new, rapidly growing field related to the study and treatment of brain circuits. Establishing safety cutoffs for focused ultrasound is crucial for non-ablative neurological ultrasound experiments. In addition to potential focal heating, there is concern about temperature elevation at the skin surface. Much work has been performed at or near the FDA guideline of ISPTA.3 = 720 mW/cm2, which technically only applies to diagnostic, not therapeutic, ultrasound. Furthermore, evidence of brain tissue damage on histology in the focal region has been shown not to occur until ISPTA.3 > 14 W/cm2. Therefore, this study was conducted across a range of intensities between these two values, evaluating both subjective and objective side effects. Subjective side effects encompassed any discomfort experienced during and after focused ultrasound stimulation, while objective side effects included clinical findings of skin irritation, such as erythema, edema, or burns. This study also examined how the skin temperature at the skin-transducer interface would change in order to assess whether there would be significant heating. The subjects did not experience any unpleasant sensation at the point of stimulation, including heat or pain, and no objective findings of skin irritation were observed following stimulation and the removal of the transducer. In addition, there was no intensity-dependent effect on temperature, and the maximal rise in temperature was 1.45 °C, suggesting that these parameters do not result in the heating of the skin at the interface in such a way that poses a risk to subjects when operating at or below the intensities tested in this experiment.

Keywords: heating; skin; temperature; ultrasound.

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Conflict of interest statement

Mr. Spivak is a consultant for BrainSonix Inc. Dr. Korb is a Vice-President of BrainSonix Inc. Dr. Korb also owns shares in the company. Dr. Schafer is a consultant for BrainSonix Inc. Dr. Bystritsky is the CEO and a shareholder of Brainsonix. Dr. Kuhn is a consultant and shareholder of Sanmai Technologies, PBC. The other authors report no conflicts of interest.

Figures

Figure 1
Figure 1
Brainsonix BX Pulsar 1002 ultrasound console.
Figure 2
Figure 2
Brainsonix BX Pulsar 1002 FUS transducer.
Figure 3
Figure 3
Change in temperature following ultrasound stimulation at different intensity levels.
See this image and copyright information in PMC

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