Thermo‐acoustic ultrasound for noninvasive temperature monitoring at lead tips during MRI

Dixit, Neerav; Pauly, John M.; Scott, Greig

doi:10.1002/mrm.28152

Cited by 5 publications

(13 citation statements)

References 41 publications

(46 reference statements)

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“…This can be accomplished using either pulsed TAUS, in which the time delay between a pulsed excitation and signal reception is used for ranging, or acquisition methods that encode range in the frequency‐domain, such as frequency‐modulated continuous‐wave (FMCW) TAUS. In FMCW TAUS, the intensity of the microwave excitation is modulated by a linear frequency modulation (LFM) chirp signal that sweeps through the desired acoustic excitation frequencies, exciting acoustic chirps at the sites of microwave absorption 18,19,27 . Mixing of a detected TAUS signal with the chirp used for modulation yields beat frequencies that are proportional to the distances between the absorption sites and the detector.…”

Section: Methodsmentioning

confidence: 99%

“…16,17 Electrically conductive materials that are implanted in the body can interact with the RF/microwave fields that are applied for TAUS excitations, markedly enhancing the power absorption density and TAUS signal generation around the implants. [18][19][20] Figure 1 shows how this phenomenon can be used for TAUS-based lumpectomy guidance. If a small, conductive marker is implanted at the tumor site, RF/microwave excitations applied to the breast can generate TAUS signals from the marker.…”

Section: Introductionmentioning

confidence: 99%

“…In TAUS, radiofrequency (RF) or microwave excitations are applied to the body to excite acoustic signals, which are then detected and used to localize the sites of EM absorption in the body 16,17 . Electrically conductive materials that are implanted in the body can interact with the RF/microwave fields that are applied for TAUS excitations, markedly enhancing the power absorption density and TAUS signal generation around the implants 18‐20 . Figure 1 shows how this phenomenon can be used for TAUS‐based lumpectomy guidance.…”

Section: Introductionmentioning

confidence: 99%

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Biopsy marker localization with thermo‐acoustic ultrasound for lumpectomy guidance

et al. 2021

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Purpose: Almost one in four lumpectomies fails to fully remove cancerous tissue from the breast, requiring reoperation. This high failure rate suggests that existing lumpectomy guidance methods are inadequate for allowing surgeons to consistently identify the proper volume of tissue for excision. Current guidance techniques either provide little information about the tumor position or require surgeons to frequently switch between making incisions and manually probing for a marker placed at the lesion site. This article explores the feasibility of thermo-acoustic ultrasound (TAUS) to enable hands-free localization of metallic biopsy markers throughout surgery, which would allow for continuous visualization of the lesion site in the breast without the interruption of surgery.In a TAUS-based localization system, microwave excitations would be transmitted into the breast, and the amplification in microwave absorption around the metallic markers would generate acoustic signals from the marker sites through the thermo-acoustic effect. Detection and ranging of these signals by multiple acoustic receivers on the breast could then enable marker localization through acoustic multilateration. Methods: Physics simulations were used to characterize the TAUS signals generated from different markers by microwave excitations. First, electromagnetic simulations determined the spatial pattern of the amplification in microwave absorption around the markers. Then, acoustic simulations characterized the acoustic fields generated from these markers at various acoustic frequencies.TAUS-based one-dimensional (1D) ranging of two metallic markers-including a biopsy marker that is FDA-approved for clinical use-immersed in saline was also performed using a bench-top setup. To perform TAUS acquisitions, a microwave applicator was driven by 2.66 GHz microwave signals that were amplitude-modulated by chirps at the desired acoustic excitation frequencies, and the resulting TAUS signal from the markers was detected by an ultrasonic transducer. Results:The simulation results show that the geometry of the marker strongly impacts the quantity and spatial pattern of both the microwave absorption around the marker and the resulting TAUS signal generated from the marker. The How to cite this article: Dixit N, Daniel BL, Hargreaves BA, Pauly JM, Scott GC. Biopsy marker localization with thermo-acoustic ultrasound for lumpectomy guidance.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Biopsy marker localization with thermo‐acoustic ultrasound for lumpectomy guidance

et al. 2021

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“…[139,140] To overcome the limitation of the unreal-time monitoring of MRI, a combination of MRI with other methods has become a new point of focus in research. Dixit et al [141] attempted to monitor temperature during MRI using thermoacoustic ultrasound (TAUS), and found that the TAUS signals could accurately estimate the needle tip temperature. Bour et al [142] proposed a new acquisition sequence for multi-slice, simultaneous, and sub-second imaging of tissue temperature during ablation.…”

Section: Real-time Temperature Monitoringmentioning

confidence: 99%

Design and Challenges of Sonodynamic Therapy System for Cancer Theranostics: From Equipment to Sensitizers

2021

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As a novel noninvasive therapeutic modality combining low-intensity ultrasound and sonosensitizers, sonodynamic therapy (SDT) is promising for clinical translation due to its high tissue-penetrating capability to treat deeper lesions intractable by photodynamic therapy (PDT), which suffers from the major limitation of low tissue penetration depth of light. The effectiveness and feasibility of SDT are regarded to rely on not only the development of stable and flexible SDT apparatus, but also the screening of sonosensitizers with good specificity and safety. To give an outlook of the development of SDT equipment, the key technologies are discussed according to five aspects including ultrasonic dose settings, sonosensitizer screening, tumor positioning, temperature monitoring, and reactive oxygen species (ROS) detection. In addition, some state-of-the-art SDT multifunctional equipment integrating diagnosis and treatment for accurate SDT are introduced. Further, an overview of the development of sonosensitizers is provided from small molecular sensitizers to nano/microenhanced sensitizers. Several types of nanomaterial-augmented SDT are in discussion, including porphyrin-based nanomaterials, porphyrin-like nanomaterials, inorganic nanomaterials, and organic-inorganic hybrid nanomaterials with different strategies to improve SDT therapeutic efficacy. There is no doubt that the rapid development and clinical translation of sonodynamic therapy will be promoted by advanced equipment, smart nanomaterial-based sonosensitizer, and multidisciplinary collaboration.

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“…The effects of radiofrequency (RF) radiation on biological tissue have been the subject of intensive research for many decades [1][2][3] , amplified by the advent of cellular communications. The omnipresence of Cell Towers in cities led to new urgency for understanding the effects of RF fields on the brain [4][5][6][7][8] . Recent and ongoing development of novel technologies expands RF applications to higher frequencies (e.g., in millimeter wave and in 5G cellular communication) and higher power levels (e.g., in high power microwave (HPM)), leading to a wider variation in public health RF exposure scenarios 9,10 .…”

Section: Introductionmentioning

confidence: 99%

Brain-implanted conductors amplify radiofrequency fields in rodents: advantages and risks

Vöröslakos

Yaghmazadeh

Alon

et al. 2022

Preprint

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Over the past few decades, daily exposure to radiofrequency (RF) fields has been increasing due to the rapid development of wireless and medical imaging technologies. Under extreme circumstances, exposure to very strong RF energy can lead to heating of body tissue, even resulting in tissue injury. The presence of implanted devices, moreover, can amplify RF effects on surrounding tissue. Therefore, it is important to understand the interactions of RF fields with tissue in the presence of implants, in order to establish appropriate wireless safety protocols, and also to extend the benefits of medical imaging to increasing numbers of people with implanted medical devices. This study explored the neurological effects of RF exposure in rodents implanted with neuronal recording electrodes. We exposed freely moving and anesthetized rats and mice to 950 MHz RF energy while monitoring their brain activity, temperature, and behavior. We found that RF exposure could induce fast onset firing of single neurons without heat injury. In addition, brain implants enhanced the effect of RF stimulation resulting in reversible behavioral changes. Using an optical temperature measurement system, we found greater than tenfold increase in brain temperature in the vicinity of the implant. On the one hand, our results underline the importance of careful safety assessment for brain implanted devices, but on the other hand, we also show that metal implants may be used for neurostimulation if brain temperature can be kept within safe limits.

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Thermo‐acoustic ultrasound for noninvasive temperature monitoring at lead tips during MRI

Cited by 5 publications

References 41 publications

Biopsy marker localization with thermo‐acoustic ultrasound for lumpectomy guidance

Biopsy marker localization with thermo‐acoustic ultrasound for lumpectomy guidance

Design and Challenges of Sonodynamic Therapy System for Cancer Theranostics: From Equipment to Sensitizers

Brain-implanted conductors amplify radiofrequency fields in rodents: advantages and risks

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