Real-time Magnetic Resonance–guided High-intensity Focused Ultrasound Focal Therapy for Localised Prostate Cancer: Preliminary Experience

Napoli, Alessandro; Anzidei, Michele; Nunzio, Cosimo De; Cartocci, Gaia; Panebianco, Valeria; Dominicis, C. De; Catalano, Carlo; Petrucci, F.; Leonardo, Costantino

doi:10.1016/j.eururo.2012.11.002

Cited by 128 publications

(104 citation statements)

References 6 publications

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“…Simulations and preliminary experiments demonstrate the feasibility of delivering protracted mild hyperthermia [40][41][42][43][44][45] • C for >15-30 min to the prostate with ExAblate 2100 ERUS prostate ablation system. Phased array beamforming techniques may be used to tailor acoustic energy deposition pattern in 3D, along array length and angular expanse.…”

Section: Discussionmentioning

confidence: 99%

“…[41][42][43] Potentially, it can be fast tracked into the clinic for hyperthermia applications as well. Feasibility of safe hyperthermia delivery to the prostate using transrectal ultrasound arrays (∼1.5 MHz, 4-16 elements) has been reported in the past.…”

Section: Discussionmentioning

confidence: 99%

“…Based on real time MR temperature imaging (MRTI), the ERUS array can be utilized to translate (mechanical or electronic scanning) a small HIFU focal pattern in 3D and perform repetitive ablations to coagulate overlapping lesions that cumulatively cover the entire target volume. 41,42 In contrast to HIFU, hyperthermia requires more diffused energy deposition sustained over longer durations to establish uniform temperature distribution and sufficient thermal dose within the entire targeted volume. Array beamforming and phasing requirements of these sonications are very different from conventional HIFU exposures [Figs.…”

Section: Introductionmentioning

confidence: 99%

“…[1][2][3][4][5][6] Mild hyperthermia (40)(41)(42)(43)(44)(45) • C) can induce direct cytotoxicity in tumors, radiosensitize cancer cells by impairing DNA repair mechanisms, and enhance blood flow in tumor microenvironments to increase tumor oxygenation and facilitate drug delivery. 7 It may also be used to enhance localized drug delivery 8 and gene therapy 9 as reported in some recent investigations.…”

Section: Introductionmentioning

confidence: 99%

“…[41][42][43] If it can be successfully adapted for protracted hyperthermia, it can be potentially fast-tracked for clinical application. With this motivation, this initial study employed theoretical and experimental techniques to identify operational modifications, and assess the feasibility and capability of safe and reliable MRguided prostate hyperthermia with the ExAblate 2100 prostate applicator.…”

Section: Introductionmentioning

confidence: 99%

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Model‐based feasibility assessment and evaluation of prostate hyperthermia with a commercial MR‐guided endorectal HIFU ablation array

et al. 2014

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Purpose: Feasibility of targeted and volumetric hyperthermia (40-45• C) delivery to the prostate with a commercial MR-guided endorectal ultrasound phased array system, designed specifically for thermal ablation and approved for ablation trials (ExAblate 2100, Insightec Ltd.), was assessed through computer simulations and tissue-equivalent phantom experiments with the intention of fast clinical translation for targeted hyperthermia in conjunction with radiotherapy and chemotherapy. Methods: The simulations included a 3D finite element method based biothermal model, and acoustic field calculations for the ExAblate ERUS phased array (2.3 MHz, 2.3 × 4.0 cm 2 , ∼1000 channels) using the rectangular radiator method. Array beamforming strategies were investigated to deliver protracted, continuous-wave hyperthermia to focal prostate cancer targets identified from representative patient cases. Constraints on power densities, sonication durations and switching speeds imposed by ExAblate hardware and software were incorporated in the models. Preliminary experiments included beamformed sonications in tissue mimicking phantoms under MR temperature monitoring at 3 T (GE Discovery MR750W). Results: Acoustic intensities considered during simulation were limited to ensure mild hyperthermia (T max < 45• C) and fail-safe operation of the ExAblate array (spatial and time averaged acoustic intensity I SATA < 3.4 W/cm 2 ). Tissue volumes with therapeutic temperature levels (T > 41 • C) were estimated. Numerical simulations indicated that T > 41• C was calculated in 13-23 cm 3 volumes for sonications with planar or diverging beam patterns at 0.9-1.2 W/cm 2 , in 4.5-5.8 cm 3 volumes for simultaneous multipoint focus beam patterns at ∼0.7 W/cm 2 , and in ∼6.0 cm 3 for curvilinear (cylindrical) beam patterns at 0.75 W/cm 2 . Focused heating patterns may be practical for treating focal disease in a single posterior quadrant of the prostate and diffused heating patterns may be useful for heating quadrants, hemigland volumes or even bilateral targets. Treatable volumes may be limited by pubic bone heating. Therapeutic temperatures were estimated for a range of physiological parameters, sonication duty cycles and rectal cooling. Hyperthermia specific phasing patterns were implemented on the ExAblate prostate array and continuous-wave sonications (∼0.88 W/cm 2 , 15 min) were performed in tissue-mimicking material with real-time MR-based temperature imaging (PRFS imaging at 3.0 T). Shapes of heating patterns observed during experiments were consistent with simulations. Conclusions: The ExAblate 2100, designed specifically for thermal ablation, can be controlled for delivering continuous hyperthermia in prostate while working within operational constraints.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Model‐based feasibility assessment and evaluation of prostate hyperthermia with a commercial MR‐guided endorectal HIFU ablation array

et al. 2014

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Focal Therapy of Prostate Cancer

Tay

Polascik

2018

Smith's Textbook of Endourology

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Improving thermal dose accuracy in magnetic resonance-guided focused ultrasound surgery: Long-term thermometry using a prior baseline as a reference

Bitton

Webb

Pauly

et al. 2015

J. Magn. Reson. Imaging

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Purpose To investigate thermal dose volume (TDV) and non-perfused volume (NPV) of magnetic resonance-guided focused ultrasound (MRgFUS) treatments in patients with soft tissue tumors, and describe a method for MR thermal dosimetry using a baseline reference. Materials and Methods Agreement between TDV and immediate post treatment NPV was evaluated from MRgFUS treatments of five patients with biopsy-proven desmoid tumors. Thermometry data (gradient echo, 3T) were analyzed over the entire course of the treatments to discern temperature errors in the standard approach. The technique searches previously acquired baseline images for a match using 2D normalized cross-correlation and a weighted mean of phase difference images. Thermal dose maps and TDVs were recalculated using the matched baseline and compared to NPV. Results TDV and NPV showed between 47%–91% disagreement, using the standard immediate baseline method for calculating TDV. Long-term thermometry showed a nonlinear local temperature accrual, where peak additional temperature varied between 4–13°C (mean = 7.8°C) across patients. The prior baseline method could be implemented by finding a previously acquired matching baseline 61% ± 8% (mean ± SD) of the time. We found 7%–42% of the disagreement between TDV and NPV was due to errors in thermometry caused by heat accrual. For all patients, the prior baseline method increased the estimated treatment volume and reduced the discrepancies between TDV and NPV (P = 0.023). Conclusion This study presents a mismatch between in-treatment and post treatment efficacy measures. The prior baseline approach accounts for local heating and improves the accuracy of thermal dose-predicted volume.

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Real-time Magnetic Resonance–guided High-intensity Focused Ultrasound Focal Therapy for Localised Prostate Cancer: Preliminary Experience

Cited by 128 publications

References 6 publications

Model‐based feasibility assessment and evaluation of prostate hyperthermia with a commercial MR‐guided endorectal HIFU ablation array

Model‐based feasibility assessment and evaluation of prostate hyperthermia with a commercial MR‐guided endorectal HIFU ablation array

Focal Therapy of Prostate Cancer

Improving thermal dose accuracy in magnetic resonance-guided focused ultrasound surgery: Long-term thermometry using a prior baseline as a reference

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