High-Precision Thermotherapy
for Small Lesions

Lizzi, Frederic L.

doi:10.1159/000474675

Cited by 25 publications

(6 citation statements)

References 14 publications

(26 reference statements)

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“…Frequency-domain implementations usually employ spectrum by focused ultrasound [24]. Similar needs exist for evaluating ultrasonic hyperthermia which is employed to treat larger tissue analysis of coherent rf signals from temporally gated tissue segments, and they derive average spectra that describe the mean volumes [25].…”

mentioning

confidence: 99%

Ultrasonic spectrum analysis for tissue assays and therapy evaluation

Lizzi

Astor

Liu

et al. 1997

Int. J. Imaging Syst. Technol.

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173

163

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mentioning

confidence: 99%

Ultrasonic spectrum analysis for tissue assays and therapy evaluation

Lizzi

Astor

Liu

et al. 1997

Int. J. Imaging Syst. Technol.

Self Cite

173

163

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“…In some cases, the combined effect of high acoustic pressure and rapid heating may generate unwanted macroscopic cavities or tissue fragmentation. These events, which result in destruction of local tissue integrity and changes of material properties, not only cause inefficient ablation of distal tissue segments [26] and altered lesion location, shape, and size from the original treatment plan, but also render the prediction of tissue status from temperature measurement difficult.…”

Section: Introductionmentioning

confidence: 99%

Characterization of lesion formation and bubble activities during high-intensity focused ultrasound ablation using temperature-derived parameters

Hsiao

Kumon

Deng

2013

Infrared Physics & Technology

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Successful high-intensity focused ultrasound (HIFU) thermal tissue ablation relies on accurate information of the tissue temperature and tissue status. Often temperature measurements are used to predict and monitor the ablation process. In this study, we conducted HIFU ablation experiments with ex vivo porcine myocardium tissue specimens to identify changes in temperature associated with tissue coagulation and bubble/cavity formation. Using infrared (IR) thermography and synchronized bright-field imaging with HIFU applied near the tissue surface, parameters derived from the spatiotemporal evolution of temperature were correlated with HIFU-induced lesion formation and overheating, of which the latter typically results in cavity generation and/or tissue dehydration. Emissivity of porcine myocardium was first measured to be 0.857 ± 0.006 (n = 3). HIFU outcomes were classified into non-ablative, normal lesion, and overheated lesion. A marked increase in the rate of temperature change during HIFU application was observed with lesion formation. A criterion using the maximum normalized second time derivative of temperature change provided 99.1% accuracy for lesion identification with a 0.05 s−1 threshold. Asymmetric temperature distribution on the tissue surface was observed to correlate with overheating and/or bubble generation. A criterion using the maximum displacement of the spatial location of the peak temperature provided 90.9% accuracy to identify overheated lesion with a 0.16 mm threshold. Spatiotemporal evolution of temperature obtained using IR imaging allowed determination of the cumulative equivalent minutes at 43 °C (CEM43) for lesion formation to be 170 min. Similar temperature characteristics indicative of lesion formation and overheating were identified for subsurface HIFU ablation. These results suggest that parameters derived from temperature changes during HIFU application are associated with irreversible changes in tissue and may provide useful information for monitoring HIFU treatment.

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“…The gas bodies that often form during HIFU ablation can be caused by inertial cavitation, tissue degassing, and/or boiling due to increased temperature during HIFU exposure [29]. These gas bodies strongly scatter ultrasound and distort the HIFU beam, resulting in inefficient ablation of distal tissue segment [30] and altered lesion location, shape and size from the original treatment plan. The presence of gas bodies can also result in enhanced heating beyond thermoviscous absorption [31].…”

Section: Introductionmentioning

confidence: 99%

High-frequency rapid B-mode ultrasound imaging for real-time monitoring of lesion formation and gas body activity during high-intensity focused ultrasound ablation

Gudur

Kumon

Zhou

et al. 2012

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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The goal of this study was to examine the ability of high-frame-rate, high-resolution imaging to monitor tissue necrosis and gas-body activities formed during high-intensity focused ultrasound (HIFU) application. Ex vivo porcine cardiac tissue specimens (n = 24) were treated with HIFU exposure (4.33 MHz, 77 to 130 Hz pulse repetition frequency (PRF), 25 to 50% duty cycle, 0.2 to 1 s, 2600 W/cm(2)). RF data from B-mode ultrasound imaging were obtained before, during, and after HIFU exposure at a frame rate ranging from 77 to 130 Hz using an ultrasound imaging system with a center frequency of 55 MHz. The time history of changes in the integrated backscatter (IBS), calibrated spectral parameters, and echo-decorrelation parameters of the RF data were assessed for lesion identification by comparison against gross sections. Temporal maximum IBS with +12 dB threshold achieved the best identification with a receiver-operating characteristic (ROC) curve area of 0.96. Frame-to-frame echo decorrelation identified and tracked transient gas-body activities. Macroscopic (millimeter-sized) cavities formed when the estimated initial expansion rate of gas bodies (rate of expansion in lateral-to-beam direction) crossed 0.8 mm/s. Together, these assessments provide a method for monitoring spatiotemporal evolution of lesion and gas-body activity and for predicting macroscopic cavity formation.

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High-Precision Thermotherapy for Small Lesions

Cited by 25 publications

References 14 publications

Ultrasonic spectrum analysis for tissue assays and therapy evaluation

Ultrasonic spectrum analysis for tissue assays and therapy evaluation

Characterization of lesion formation and bubble activities during high-intensity focused ultrasound ablation using temperature-derived parameters

High-frequency rapid B-mode ultrasound imaging for real-time monitoring of lesion formation and gas body activity during high-intensity focused ultrasound ablation

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