Measured acoustic intensities for clinical diagnostic ultrasound transducers and correlation with thermal index

Retz, K.; Kotopoulis, Spiros; Kiserud, Torvid; Matre, Knut; Eide, Geir Egil; Sande, Ragnar Kvie

doi:10.1002/uog.17298

Cited by 12 publications

(7 citation statements)

References 34 publications

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“…Alternatively, these voltage recordings can be converted into intensities using a pulse intensity integral measured in watts per centimeter squared (i.e., W/cm 2 ). When these intensities are calculated using a hydrophone in a degassed water tank (Retz et al, 2017 ), the intensity is not derated (I spta .0 ) or (I sppa .0 ) for any tissue attenuation, which can be assumed as a uniform 0.3 dB/cm-MHz derating and reported as a derated (I spta .3 ) or (I sppa .3 ) (Schafer et al, 2020 ). However, this uniform attenuation does not account for the skull, which can attenuate between 50% and 80% (Mueller et al, 2017 ; Legon et al, 2018a ; Phipps et al, 2019 ) of the pressure.…”

Section: Introduction To Ultrasound Mechanicsmentioning

confidence: 99%

Current State of Potential Mechanisms Supporting Low Intensity Focused Ultrasound for Neuromodulation

Dell’Italia¹,

Sanguinetti

Monti

et al. 2022

Front. Hum. Neurosci.

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Low intensity focused ultrasound (LIFU) has been gaining traction as a non-invasive neuromodulation technology due to its superior spatial specificity relative to transcranial electrical/magnetic stimulation. Despite a growing literature of LIFU-induced behavioral modifications, the mechanisms of action supporting LIFU's parameter-dependent excitatory and suppressive effects are not fully understood. This review provides a comprehensive introduction to the underlying mechanics of both acoustic energy and neuronal membranes, defining the primary variables for a subsequent review of the field's proposed mechanisms supporting LIFU's neuromodulatory effects. An exhaustive review of the empirical literature was also conducted and studies were grouped based on the sonication parameters used and behavioral effects observed, with the goal of linking empirical findings to the proposed theoretical mechanisms and evaluating which model best fits the existing data. A neuronal intramembrane cavitation excitation model, which accounts for differential effects as a function of cell-type, emerged as a possible explanation for the range of excitatory effects found in the literature. The suppressive and other findings need additional theoretical mechanisms and these theoretical mechanisms need to have established relationships to sonication parameters.

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Section: Introduction To Ultrasound Mechanicsmentioning

confidence: 99%

Current State of Potential Mechanisms Supporting Low Intensity Focused Ultrasound for Neuromodulation

Dell’Italia¹,

Sanguinetti

Monti

et al. 2022

Front. Hum. Neurosci.

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“…Doppler since in routine settings [8] the TIb is as high as 2.1, 2.6, and 3.0 in the first, second, and third trimester, respectively. In addition to aspects of operator awareness, there have been some reported concerns over the ability of the bioeffect indices to predict the intensity of ultrasound [17,34]. This is because the bioeffect indices definitions have several weaknesses: TI and MI do not take into account practical imaging factors like a long fluid path (full bladder, polyhydramnios) or obesity, and the reported outputs are not necessarily equivalent to those calculated in the laboratory [17,34].…”

Section: Discussionmentioning

confidence: 99%

Safety Indices of Ultrasound: Adherence to Recommendations and Awareness During Routine Obstetric Ultrasound Scanning

et al. 2020

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Purpose To analyze bioeffect safety indices and assess how often operators look at these indices during routine obstetric ultrasound. Materials and Methods Automated analysis of prospectively collected data including video recordings of full-length ultrasound scans coupled with operator eye tracking was performed. Using optical recognition, we extracted the Mechanical Index (MI), Thermal Index in soft tissue (TIs), and Thermal Index in bone (TIb) values and ultrasound mode. This allowed us to report the bioeffect safety indices during routine obstetric scans and assess adherence to professional organization recommendations. Eye-tracking analysis allowed us to assess how often operators look at the displayed bioeffect safety indices. Results A total of 637 ultrasound scans performed by 17 operators were included, of which 178, 216, and 243 scans were first, second, and third-trimester scans, respectively. During live scanning, the mean and range were 0.14 (0.1 to 3.0) for TIb, 0.2 (0.1 to 1.2) for TIs, and 0.9 (0.1 to 1.3) for MI. The mean and standard deviation of TIb were 0.15 ± 0.03, 0.23 ± 0.09, 0.32 ± 0.24 in the first, second, and third trimester, respectively. For B-mode, the highest TIb was 0.8 in all trimesters. The highest TIb was recorded for pulsed-wave Doppler mode in all trimesters. The recommended exposure times were maintained in all scans. Analysis of eye tracking suggested that operators looked at bioeffect safety indices in only 27 (4.2 %) of the scans. Conclusion In this study, recommended bioeffect indices were adhered to in all routine scans. However, eye tracking showed that operators rarely assessed safety indices during scanning.

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“…Daher bedeutet ein TI von 1,5 eine maximale theoretische Erhöhung der Gewebetemperatur um 1,5°Celsius. Obwohl der TI seine Grenzen hat [2], bleibt er ein wichtiger Echtzeit-Sicherheitsparameter. Es wurden 3 verschiedene thermische Indizes entwickelt, um die Absorptionseigenschaften verschiedener Gewebe zu berücksichtigen: TIS (Soft-Tissue-Thermal-Index), TIB (Bone-Thermal-Index) für Knochen im Fokus und TIC (Cranial-Bone-Thermal-Index) für direkte kraniale Anwendungen.…”

Section: Elastographyunclassified

“…Hence, a TI of 1.5 indicates a maximal theoretical tissue temperature increase of 1.5 degrees Celsius. Although the TI has its limitations [2], it remains an important real-time safety parameter. Three different thermal indices have been developed to allow for the absorption properties of different tissues: Thermal Index for Soft Tissue (TIS), Thermal Index for Bone (TIB, for use when there is bone in the scanning field) and Thermal Index for Cranial Bone (TIC, for direct cranial insonation).…”

Section: Introductionmentioning

confidence: 99%

Safety Aspects of Perinatal Ultrasound

et al. 2021

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Ultrasound safety is of particular importance in fetal and neonatal scanning. Fetal tissues are vulnerable and often still developing, the scanning depth may be low, and potential biological effects have been insufficiently investigated. On the other hand, the clinical benefit may be considerable. The perinatal period is probably less vulnerable than the first and second trimesters of pregnancy, and ultrasound is often a safer alternative to other diagnostic imaging modalities. Here we present step-by-step procedures for obtaining clinically relevant images while maintaining ultrasound safety. We briefly discuss the current status of the field of ultrasound safety, with special attention to the safety of novel modalities, safety considerations when ultrasound is employed for research and education, and ultrasound of particularly vulnerable tissues, such as the neonatal lung. This CME is prepared by ECMUS, the safety committee of EFSUMB, with contributions from OB/GYN clinicians with a special interest in ultrasound safety.

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Measured acoustic intensities for clinical diagnostic ultrasound transducers and correlation with thermal index

Abstract: TIB is a poor predictor for I and I and for the potential bioeffects of clinical diagnostic ultrasound scanners. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

Cited by 12 publications

References 34 publications

Current State of Potential Mechanisms Supporting Low Intensity Focused Ultrasound for Neuromodulation

Current State of Potential Mechanisms Supporting Low Intensity Focused Ultrasound for Neuromodulation

Safety Indices of Ultrasound: Adherence to Recommendations and Awareness During Routine Obstetric Ultrasound Scanning

Safety Aspects of Perinatal Ultrasound

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