Real-Time Tissue Change Monitoring on the Sonablate® 500 during High Intensity Focused Ultrasound (HIFU) Treatment of Prostate Cancer

Chen, Wo‐Hsing; Sanghvi, Narendra T.; Carlson, Roy; Uchida, Τοyoaki; Matsumoto, Yoichiro; Crum, Lawrence A.; Haar, Gail Reinette ter

doi:10.1063/1.3607939

Cited by 9 publications

(14 citation statements)

References 7 publications

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“…30,31 The authors developed a color mapping based on the change in ultrasound backscatter energy for differentiating between treated and untreated tissue. 30,31 …”

Section: Introductionmentioning

confidence: 99%

Quantitative Ultrasound Imaging for Monitoring In Situ High-Intensity Focused Ultrasound Exposure

et al. 2014

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Quantitative ultrasound (QUS) imaging is hypothesized to map temperature elevations induced in tissue with high spatial and temporal resolution. To test this hypothesis, QUS techniques were examined to monitor high-intensity focused ultrasound (HIFU) exposure of tissue. In situ experiments were conducted on mammary adenocarcinoma tumors grown in rats and lesions were formed using a HIFU system. A thermocouple was inserted into the tumor to provide estimates of temperature at one location. Backscattered time-domain waveforms from the tissue during exposure were recorded using a clinical ultrasonic imaging system. Backscatter coefficients were estimated using a reference phantom technique. Two parameters were estimated from the backscatter coefficient (effective scatterer diameter (ESD) and effective acoustic concentration (EAC). The changes in the average parameters in the regions corresponding to the HIFU focus over time were correlated to the temperature readings from the thermocouple. The changes in the EAC parameter were consistently correlated to temperature during both heating and cooling of the tumors. The changes in the ESD did not have a consistent trend with temperature. The mean ESD and EAC before exposure were 120 ± 16 μm and 32 ± 3 db/cm3, respectively, and changed to 144 ± 9 μm and 51 ± 7 db/cm3, respectively, just before the last HIFU pulse was delivered to the tissue. After the tissue cooled down to 37°C, the mean ESD and EAC were 126 ± 8 μm and 35 ± 4 db/cm3, respectively. Peak temperature in the range of 50–60°C was recorded by a thermocouple placed just behind the tumor. These results suggest that QUS techniques have the potential to be used for non-invasive monitoring of HIFU exposure.

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“…30,31 The authors developed a color mapping based on the change in ultrasound backscatter energy for differentiating between treated and untreated tissue. 30,31 …”

Section: Introductionmentioning

confidence: 99%

Quantitative Ultrasound Imaging for Monitoring In Situ High-Intensity Focused Ultrasound Exposure

et al. 2014

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“…The TCM signal processing algorithms are described in detail by Chen et al [20, 21] and briefly presented below. The backscattered pulse-echo signals are analyzed in the frequency domain using the Fast Fourier Transform (FFT) to derive the ΔE value for each ablative site as described by eqs.…”

Section: Methods (Backscattering Data Acquisition and Temperature Meamentioning

confidence: 99%

“…Eight histologically confirmed organ confined prostate cancer patients were enrolled as per the clinical study protocol [22] with intent to ablate the entire prostate gland with the TCM software based Sonablate 500 device [21, 23]. All patients were under local epidural anesthesia for the HIFU procedure.…”

Section: Methods (Backscattering Data Acquisition and Temperature Meamentioning

confidence: 99%

Clinical validation of real-time tissue change monitoring during prostate tissue ablation with high intensity focused ultrasound

Sanghvi

Chen²,

Carlson

et al. 2017

J Ther Ultrasound

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BackgroundThe purpose of these clinical studies was to validate a Tissue Change Monitoring (TCM) algorithm in vivo. TCM is a quantitative tool for the real-time assessment of HIFU dose. TCM provides quantitative analysis of the backscatter pulse echo signals (pre and immediately post HIFU) for each individual ablative site, using ultrasonic tissue characterization as a surrogate for monitoring tissue temperature. Real-time analysis generates an energy difference parameter (ΔE in dB) that is proportional to tissue temperature.MethodsPost in vitro studies, two clinical studies were conducted to validate the TCM algorithm on the Sonablate® device. Studies enrolled histologically confirmed, organ confined prostate cancer patients. The first clinical study was conducted in two phases for whole gland ablation. First eight patients’ data were used to measure the algorithm performance followed by 89 additional patients for long term outcome. The second clinical study enrolled five patients; four patients with focal cancer had hemi-ablation only and one had whole gland ablation. Four 3 Fr. needles containing three thermocouples each were placed transperineally in the prostate to record tissue temperatures in the focal zone, posterior to the focal zone and on the lateral gland where no HIFU was applied. Tissue temperatures from the focal zone were correlated to the ΔE parameter.ResultsIn the first clinical study, the average TCM rate was 86%. Pre and 6 months post HIFU, median PSA was 7.64 and 0.025 ng/ml respectively and 97% patients had negative biopsy. For the second clinical study, the measured prostate tissue temperatures (Average, Max, and Min) in the ablation zones were 84°, 114° and 60 °C and the corresponding ΔE (dB/10) parameters were 1.05, 2.6 and 0.4 resulting in 83% of temperatures in the range of 75°-100 °C and 17% in the 60°-74 °C range. Outside the focal zone, the average temperature was 50 °C and in the lateral lobe where no HIFU was applied, peak temperature was 40.7 °C.ConclusionsThe TCM algorithm is able to estimate tissue changes reliably during the HIFU procedure for prostate tissue ablation in real-time and can be used as a guide for HIFU dose delivery and tissue ablation control.

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“…In addition, the vulnerability to motion artifacts and tissue deformation limit the quantitative assessment. Therefore, one of the commercial HIFU systems only illustrates the low, medium and high degree of change in backscattered energy levels to provide qualitative information [12]. In contrast, although the cost of MRI is quite high, the ability of providing real-time thermography makes MRI the sole HIFU guidance modality approved by FDA.…”

Section: Yufeng Zhoumentioning

confidence: 99%

Thermography in High-Intensity Focused Ultrasound Ablation

Zhou¹

2012

J Appl Mech Eng

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Real-Time Tissue Change Monitoring on the Sonablate® 500 during High Intensity Focused Ultrasound (HIFU) Treatment of Prostate Cancer

Cited by 9 publications

References 7 publications

Quantitative Ultrasound Imaging for Monitoring In Situ High-Intensity Focused Ultrasound Exposure

Quantitative Ultrasound Imaging for Monitoring In Situ High-Intensity Focused Ultrasound Exposure

Clinical validation of real-time tissue change monitoring during prostate tissue ablation with high intensity focused ultrasound

Thermography in High-Intensity Focused Ultrasound Ablation

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