| Abstract |
| Further research is needed to examine the effects of ultrasound stimulation of the carotid artery on the physiological function of the brain. Hence, this study aimed to propose a method utilizing a noninvasive and quantitative thermal stimulation technique of the carotid artery employing therapeutic ultrasound to improve and maintain the physiological function of the brain.
The study was participated in by 27 healthy adults in their 20s. Diagnostic ultrasound identified the stimulation location of the right common carotid artery in the supine position, followed by the application of therapeutic ultrasound stimulation to the right sternocleidomastoid muscle. A two-minute therapeutic ultrasound stimulation was employed at two intensities (5W/cm2 and 10W/cm2) with a frequency of 3MHz. Near-infrared spectroscopy measured and compared changes in regional cerebral oxygen saturation (rSO2) and hemoglobin concentration (Hb). Furthermore, changes in each intervention section based on intensities were compared and analyzed.
The area between the scalp and cerebral cortex (shallow) exhibited rSO2 increases at 10W/cm2 and decreases at 5W/cm2 in both during and after the intervention compared to pre-intervention, although differences lacked statistical significance. On the other hand, the cerebral cortex (deep) area demonstrated a statistically significant rSO2 decrease regardless of the intensities during the intervention (p = .001 for 5W/cm2; p < .001 for 10W/cm2), followed by post-intervention recovery tendencies (p = .016 for 5W/cm2; p = . 012 for 1 0W/cm2). A significant increase in oxyhemoglobin (HbO) was illustrated during 5W/cm2 stimulation (p = .036), accompanied by a non-significant decrease in deoxyhemoglobin (HbR). Moreover, a non-significant decrease was identified in both HbO and HbR at 10W/cm2 stimulation. A significant intensity-based difference in rSO2 was observed in the shallow area (during intervention, p = .023; after intervention, p = .022).
In conclusion, results revealed that the rSO2 in the deep area decreased during the intervention when performed at a frequency of 3MHz and an intensity of 5 and 10W/cm2. At a strong intensity of 10W/cm2, the rSO2 exhibited contrasting trends, increasing in the shallow area and decreasing in the deep area. The observed phenomenon stems from the excessive blood supply to the shallow area caused by increased external carotid artery blood flow, rather than the effective cerebral cortex stimulation induced by increased internal carotid artery blood flow by strong intensity stimulation. On the other hand, HbO in the brain increased at an intensity of 5W/cm2, indicating an increased oxygen supply. Accordingly, an appropriate intensity of therapeutic ultrasound stimulation is expected to improve brain function by regulating the physiological function of the brain and enhancing cerebrovascular health through improved cerebral blood flow. |
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| Key Words |
| 근적외선분광법, 치료용 초음파, 경동맥, 대뇌산소포화도, Near-infrared Spectroscopy, Therapeutic Ultrasound, Common Carotid Artery, Cerebral Oxygen Saturation |
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