Hyperecho as the Indicator of Tissue Necrosis During Microbubble-Assisted High Intensity Focused Ultrasound: Sensitivity, Specificity and Predictive Value

Yu, Tinghe; Xu, Chi

doi:10.1016/j.ultrasmedbio.2008.01.012

Cited by 39 publications

(33 citation statements)

References 20 publications

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“…25,26 Conventional B-mode US images show variations in echogenicity and a hyperechoic region is generally used to monitor FUS. 27,28 The changes of acoustic properties, such as attenuation coefficient, 29 backscattering coefficient, 17,30 nonlinearity, 31 and elasticity 32 have been proposed for monitoring FUS treatment.…”

Section: Introductionmentioning

confidence: 99%

Feasibility of using Nakagami distribution in evaluating the formation of ultrasound-induced thermal lesions

Zhang

Zhou

Wan

et al. 2012

The Journal of the Acoustical Society of America

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The acoustic posterior shadowing effects of bubbles influence the accuracy for defining the location and range of ablated thermal lesions during focused ultrasound surgery when using ultrasonic monitoring imaging. This paper explored the feasibility of using Nakagami distribution to evaluate the ablated region induced by focused ultrasound exposures at different acoustic power levels in transparent tissue-mimicking phantoms. The mean value of the Nakagami parameter m was about 0.5 in the cavitation region and increased to around 1 in the ablated region. Nakagami images were not subject to significant shadowing effects of bubbles. Ultrasound-induced thermal lesions observed in the photos and Nakagami images were overshadowed by bubbles in the B-mode images. The lesion size predicted in the Nakagami images was smaller than that predicted in the photos due to the sub resolvable effect of Nakagami imaging at the interface. This preliminary study on tissue-mimicking phantom suggested that the Nakagami parameter m may have the potential use in evaluating the formation of ultrasound-induced thermal lesion when the shadowing effect of bubbles is strong while the thermal lesion was small. Further studies in vivo and in vitro will be needed to evaluate the potential application.

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Section: Introductionmentioning

confidence: 99%

Feasibility of using Nakagami distribution in evaluating the formation of ultrasound-induced thermal lesions

Zhang

Zhou

Wan

et al. 2012

The Journal of the Acoustical Society of America

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“…44 The formation of bubbles during lesion production is desired during ultrasound-guided HIFU therapy, since these lesions can be correlated with hyperechoic regions in ultrasound images. 21,45 Hyperecho formation can be used for treatment monitoring, 7,46 as well as pre-treatment targeting ͑to establish whether HIFU focus is indeed located at the treatment site͒. Hyperecho was shown to form even at very short HIFU exposures ͑of 30 ms͒ with no or minimal concomitant tissue damage.…”

Section: Discussionmentioning

confidence: 99%

Prevention of post‐focal thermal damage by formation of bubbles at the focus during high intensity focused ultrasound therapy

et al. 2008

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Safety concerns exist for potential thermal damage at tissue-air or tissue-bone interfaces located in the post-focal region during high intensity focused ultrasound (HIFU) treatments. We tested the feasibility of reducing thermal energy deposited at the post-focal tissue-air interfaces by producing bubbles (due to acoustic cavitation and/or boiling) at the HIFU focus. HIFU (in-situ intensities of 460-3500 W/cm2, frequencies of 3.2-5.5 MHz) was applied for 30 s to produce lesions (in turkey breast in-vitro (n = 37), and rabbit liver (n = 4) and thigh muscle in-vivo (n = 11)). Tissue temperature was measured at the tissue-air interface using a thermal (infrared) camera. Ultrasound imaging was used to detect bubbles at the HIFU focus, appearing as a hyperechoic region. In-vitro results showed that when no bubbles were present at the focus (at lower intensities of 460-850 W/cm2), the temperature at the interface increased continuously, up to 7.3 +/- 4.0 degrees C above the baseline by the end of treatment. When bubbles formed immediately after the start of HIFU treatment (at the high intensity of 3360 W/cm2), the temperature increased briefly for 3.5 s to 7.4 +/- 3.6 degrees C above the baseline temperature and then decreased to 4.0 +/- 1.4 degrees C above the baseline by the end of treatment. Similar results were obtained in in-vivo experiments with the temperature increases (above the baseline temperature) at the muscle-air and liver-air interfaces at the end of the high intensity treatment lower by 7.1 degrees C and 6.0 degrees C, respectively, as compared to the low intensity treatment. Thermal effects of HIFU at post-focal tissue-air interfaces, such as in bowels, could result in clinically significant increases in temperature. Bubble formation at the HIFU focus may provide a method for shielding the post-focal region from potential thermal damage.

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“…Microbubbles have been clinically used for contrast ultrasonography. Recent trials have shown that microbubbles assisted the assessment of tissue responses in real time improving the accuracy, sensitivity and positive predictive value (Yu and Xu, 2008c). These suggest that microbubble is an idea sensitizer for USgFU therapy.…”

Section: Preclinical Findingsmentioning

confidence: 96%

“…The appearance of a hyperechoic area within the target volume is considered as an indicator of tissue necrosis, which is used to monitor HIFU treatment (Wu et al, 2005). However, hyperecho does not necessarily mean tissue necrosis and the systemically clinical data are unavailable yet (Rivens et al, 2007;Yu et al, 2008c). Computerized tomography (CT) and MRI are the gold standard to follow up thermal ablation.…”

Section: Monitoring Tissue Responses In Real Time Hyperechomentioning

confidence: 99%

“…The accuracy, sensitivity and specificity were 48.72, 49.25 and 45.45% for liver and 55.83, 76.06 and 26.53% for kidney, respectively; the positive predictive values were 84.62% for liver and 60.00% for kidney and the negative predictive values were poor, when using hyperecho to forecast tissue necrosis. The use of microbubbles during HIFU improved the sensitivity in liver and the positive predictive value in kidney, but the negative predictive values were still low (Yu and Xu, 2008c). Thus, hyperecho can only be applied to monitor tissue responses in some tissue types.…”

Section: Monitoring Tissue Responses In Real Time Hyperechomentioning

confidence: 99%

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Hyperecho as the Indicator of Tissue Necrosis During Microbubble-Assisted High Intensity Focused Ultrasound: Sensitivity, Specificity and Predictive Value

Cited by 39 publications

References 20 publications

Feasibility of using Nakagami distribution in evaluating the formation of ultrasound-induced thermal lesions

Feasibility of using Nakagami distribution in evaluating the formation of ultrasound-induced thermal lesions

Prevention of post‐focal thermal damage by formation of bubbles at the focus during high intensity focused ultrasound therapy

Extracorporeal ultrasound-guided high intensity focused ultrasound therapy: Present limitations

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