Microwave‐induced thermoacoustic tomography through an adult human skull

An, Yan; Lin, Li; Liu, Changjun; Shi, Junhui; Na, Shuai; Wang, Lihong V.

doi:10.1002/mp.13439

Cited by 31 publications

(17 citation statements)

References 19 publications

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“…The use of multiple transducers or a transducer array for TAUS could also allow for improved SNR through receive focusing at a known lead tip position. The feasibility of transcranial TAUS signal detection has been demonstrated recently using ex vivo human skulls …”

Section: Discussionmentioning

confidence: 99%

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

Dixit

Pauly

Scott

2019

Magnetic Resonance in Med

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Purpose:We explore the use of thermo-acoustic ultrasound (TAUS) to monitor temperature at the tips of conductive device leads during MRI. Theory: In TAUS, rapid radiofrequency (RF) power deposition excites an acoustic signal via thermoelastic expansion. Coupling of the MRI RF transmit to device leads causes SAR amplification at lead tips, allowing MRI RF transmitters to excite significant lead tip TAUS signals. Because the amplitude of the TAUS signal depends on temperature, it becomes feasible to monitor the lead tip temperature during MRI by tracking the TAUS amplitude. Methods: The TAUS temperature dependence was characterized in a phantom and in tissue. To perform TAUS acquisitions in an MRI scanner, amplitude modulated RF chirps were transmitted by the body coil, and the lead tip TAUS signal was detected by an ultrasonic transducer. The TAUS signal level was correlated with the RF current induced on the lead and the associated B 1 artifacts in MRI. TAUS signals acquired during RF-induced heating were used to estimate the lead tip temperature. Results: The TAUS signal exhibited strong dependence on temperature, increasing over 30% with 10 • C of heating both in the phantom and in tissue. A lead tip TAUS signal was observed for a 100 mA rms current induced on a lead. During RF-induced heating, the TAUS signal appeared to accurately approximate the peak lead tip temperature. Conclusions: TAUS allows for noninvasive monitoring of lead tip temperature in an MRI environment. With further development, TAUS opens new avenues to improve RF device safety during MRI scans. K E Y W O R D SActive implantable medical devices, Implant heating, Interventional MRI, MRI engineering, RF safety, Thermo-acoustics

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Section: Discussionmentioning

confidence: 99%

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

Dixit

Pauly

Scott

2019

Magnetic Resonance in Med

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“…The millimeter-scale wavelength of microwave allows for deep penetration into biological tissue, including bone. Microwave has been demonstrated to penetrate >50 mm into the human skull while maintaining over 50% of its energy [14], making wireless transcranial microwave inhibition feasible.…”

Section: Tisrr Mediates Transcranial Inhibition Of Neuronsmentioning

confidence: 99%

“…Microwaves, with frequencies between 300 MHz and 300 GHz, fill the gap between optical waves and magnetic waves, yet have rarely been explored for neuromodulation. Microwaves have much longer wavelengths than photons and have been known to provide >50 mm penetration depth into the human brain noninvasively, while maintaining more than 50% of their energy [13, 14]. Microwave wavelengths are also much shorter than those of magnetic waves, promising higher spatial resolution for regional targeting.…”

Section: Introductionmentioning

confidence: 99%

Wireless Neuromodulation at Submillimeter Precision via a Microwave Split-Ring Resonator

Cheng

Yang

Marar

et al. 2022

Preprint

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Microwaves, with wavelengths on the order of millimeters, have centimeter-scale penetration depth and have been shown to reversibly inhibit neuronal activity. Yet, microwaves alone do not provide sufficient spatial precision to modulate target neurons without affecting surrounding tissues. Here, we report an implantable split-ring resonator (SRR) that generates a localized and enhanced microwave field at the gap site with submillimeter spatial precision. The SRR breaks the microwave diffraction limit and greatly enhances the efficiency of microwave inhibition. With the SRR, microwaves at dosages below the safe exposure limit are shown to inhibit neurons within 1 mm from the gap site. Application of the microwave SRR to suppress seizures in an in vivo model of epilepsy is demonstrated.

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“… Huang et al (2017) made the first preliminary attempt to detect the hemorrhage phantom with the self-built TAI system in the world and successfully imitated a simulated hemorrhage phantom beneath an isolated human skull. The study of Yan et al (2019) also indicated that thermoacoustic tomography can take images through the adult human skull. Zhao et al (2017) showed that thermoacoustic tomography could visualize numerous important brain anatomical structures in rats, and they further attempted to detect germinal matrix hemorrhage in neonatal mice ( Zhao et al, 2020 ).…”

Section: Introductionmentioning

confidence: 98%

Microwave-induced thermoacoustic imaging for the early detection of canine intracerebral hemorrhage

Peng

et al. 2022

Front. Physiol.

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Purpose: This study aimed to investigate the feasibility and validation of microwave-induced thermoacoustic imaging (TAI) for the early detection of canine intracerebral hemorrhage.Methods: A TAI system was used to record the thermoacoustic signal (TAS) of canine intracerebral hemorrhage in the study. First, the difference in TAS between deionized water, fresh ex vivo porcine blood and brain tissue was explored. Second, the canine hemorrhagic stroke model was established, and canine brain ultrasound examination and TAI examination were performed before modeling and at 0.5 h, 1 h, 2 h, 3 h, 4 h, 4.5 h, 5 h and 6 h after modeling. Finally, pathology and ultrasound were used as the reference diagnoses to verify the accuracy of the thermoacoustic imaging data.Results: The results showed that significant differences were observed in TASs among deionized water, fresh ex vivo porcine blood and brain tissue. The intensity of the thermoacoustic signal of blood was significantly higher than that of ex vivo porcine brain tissue and deionized water. The intracerebral hemorrhage model of five beagles was successfully established. Hematomas presented hyperintensity in TAI. Considering ultrasound and pathology as reference diagnoses, TAI can be used to visualize canine intracerebral hemorrhage at 0.5 h, 1 h, 2 h, 3 h, 4 h, 4.5 h, 5 h and 6 h after modeling.Conclusion: This is the first experimental study to explore the use of TAI in the detection of intracerebral hemorrhage in large live animals (canine). The results indicated that TAI could detect canine intracerebral hemorrhage in the early stage and has the potential to be a rapid and noninvasive method for the detection of intracerebral hemorrhage in humans.

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Microwave‐induced thermoacoustic tomography through an adult human skull

Cited by 31 publications

References 19 publications

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

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

Wireless Neuromodulation at Submillimeter Precision via a Microwave Split-Ring Resonator

Microwave-induced thermoacoustic imaging for the early detection of canine intracerebral hemorrhage

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