Segmentation Method for Magnetic Resonance-Guided High-Intensity Focused Ultrasound Therapy Planning.

High-intensity focused ultrasound (HIFU) is a minimally invasive therapy modality in which ultrasound beams are concentrated at a focal region, producing a rise of temperature and selective ablation within the focal volume and leaving surrounding tissues intact. HIFU has been proposed for the safe ablation of both malignant and benign tissues and as an agent for drug delivery. Magnetic resonance imaging (MRI) has been proposed as guidance and monitoring method for the therapy. The identification of regions of interest is a crucial procedure in HIFU therapy planning. This procedure is performed in the MR images. The purpose of the present research work is to implement a time-efficient and functional segmentation scheme, based on the watershed segmentation algorithm, for the MR images used for the HIFU therapy planning. The achievement of a segmentation process with functional results is feasible, but preliminary image processing steps are required in order to define the markers for the segmentation algorithm. Moreover, the segmentation scheme is applied in parallel to an MR image data set through the use of a thread pool, achieving a near real-time execution and making a contribution to solve the time-consuming problem of the HIFU therapy planning.

Marble game with optimal ferroelectric switching.

A low coercivity and, consequently, low hysteresis loss are desired properties for ferroelectric materials used in high-power and high-frequency actuators. The coercive field required for the onset of ferroelectric switching is shown to develop a strong directional anisotropy due to peculiarities of an energy surface associated with the polarization rotation. It is found that the ferroelectric anisotropy exhibits 'hard' and 'easy' switching axes similar to magnetic materials. The hard axis corresponds to 180° polarization reversal, whereas the easy axis favors 90° switching. Our results suggest that the intrinsic low coercivity and the full polarization reversal may not be achieved at the same time under uniaxial excitation. A rotating electric field excitation is proposed in order to circumvent this limitation and to guide the polarization switching along a curved path.

Suitability of a tumour-mimicking material for the evaluation of high-intensity focused ultrasound ablation under magnetic resonance guidance.

This study tests the suitability of a tumour-mimic for targeting magnetic resonance (MR)-guided high-intensity focused ultrasound (HIFU). An agarose-based tumour-mimic was injected as a warm solution that polymerized in tissue. Thermal characteristics and acoustic absorption of the mimic were observed within the values reported for tissues. The relaxation times at 3T were 1679 ± 15 ms for T1 and 41 ± 1 ms for T2. The mimic was clearly visible on in vivo images. With lower contrast the tumour-mimic was visible on T2-weighted images, where it was possible to detect the ablated tissue surrounding the mimic after sonications. HIFU sonications were performed to induce thermal ablation on and around the mimic using a Sonalleve system (Philips). MR thermometry maps were performed during HIFU. The average temperature when the sonication was done at the tumour-mimic was 67.6 ± 8.0 °C in vitro and 67.6 ± 5.0 °C in vivo. The average temperature for sonications at tissues was 68.4 ± 8.7 °C in vitro (liver) and 66.0 ± 2.6 °C in vivo (muscle), with no significant difference between tissue and tumour-mimic (p > 0.05). The tumour-mimic behaviour when using MR-guided HIFU was similar to tissues, showing that this mimic can be used as an alternative to tumour models for validating MR-guided HIFU devices targeting.

New integrated imaging high intensity focused ultrasound probe for transrectal prostate cancer treatment.

The present study proposes a new integrated imaging (II) high-intensity focused ultrasound (HIFU) probe intended as an improvement to the Ablatherm prostate cancer treatment. Because of a perforation in the center of the II probe, the expected lesion differs from the one obtained for the original Ablatherm probe. In this paper, the new geometry and the strategy followed to establish the treatment parameters are presented. The original probe has a 40-mm focal length, a 50-mm aperture and is truncated at 31 mm. The II probe has a 45-mm focal length, a 61-mm aperture, a central perforation of 25 mm and is truncated at 31 mm. Both probes operate at 3 MHz. A mathematical model for lesion prediction was used for setting the treatment parameters for the II probe. These parameters should ensure equivalence between the lesions obtained with the original and II probes. Simulation-obtained parameters were validated by in-vitro and in-vivo (on liver of 70 New Zealand rabbits) experiments. The new II probe was used clinically to treat 30 patients. The mean age was 70.9 +/- 5.3 years (SD), the mean prostate volume 26.9 +/- 7.7 mL and the mean serum prostate specific antigen (PSA) concentration before treatment was 9.2 +/- 5.5 ng/mL. Simulations showed that for the II probe acoustical power and duration when the transducer is inactive should be reduced of 14% and 1s. In-vitro and in-vivo experiments confirmed the equivalence between the lesions obtained with the two probes. The lesion volume obtained under in-vitro conditions (for a traversed tissue depth of 16 mm to the focus) was 5 +/- 0.4 cm(3) and 5.1 +/- 0.5 cm(3) for the original and II probes, respectively. Under in-vivo conditions, the lesion volume (for a traversed tissue depth of 18 mm) was 5.3 +/- 1.1 cm(3) and 5.1 +/- 1.1 cm(3) for the original and II probes, respectively. During the clinical trial, a correction of + 1s in the exposure time was required to recreate the same degree of efficacy observed with the original probe (p = 0.97): 66.7 % of negative biopsies and 75% of patients with PSA at 3 mo < or =1 ng/mL. The morbidity observed was minimal and identical to that observed with the original probe.

Influence of the docetaxel administration period (neoadjuvant or concomitant) in relation to HIFU treatment on the growth of Dunning tumors: results of a preliminary study.

The objective of this study was to evaluate mechanisms of the synergy between high intensity-focused ultrasound (HIFU) and docetaxel and to determine the best sequence of chemotherapy administration in relation to HIFU treatment for obtaining optimum control of tumoral growth. A total of 15 days after s.c. implantation of the tumor, 52 Copenhagen rats studied were randomized in 4 groups of 13: controls, docetaxel alone (group 1), HIFU and docetaxel concomitant (group 2) and HIFU and docetaxel administered 24 h before treatment (group 3). The number of HIFU shots was calculated in order to cover 75% of the tumor volume. The effects of docetaxel, HIFU and their interaction on tumor volumes were analyzed using a linear regression. The distributions of the tumor volumes were significantly greater in the control group than in the group 1 (P=0.002) and than in both groups 2 and 3 (P < 0.0001 and P = 0.0001). These volumes were also significantly greater in group 1 than in both groups 2 and 3 and there was no difference between the groups 2 and 3. The tumor doubling times were 7.8 days for the group 1, 43.8 days for the group 2, 16.1 days for the group 3 and 5.9 days for the controls. The mechanism of the synergy between HIFU and docetaxel on the growth of Dunning tumors is apparently multifaceted. The results are encouraging because in the two groups of rats treated with the combination of HIFU and docetaxel, the percentage of complete remission was approximately 30%.

Elastography for the follow-up of high-intensity focused ultrasound prostate cancer treatment: initial comparison with MRI.

We previously developed an ultrasonic elastography imaging system that may provide a simple and cost-effective solution to monitor high-intensity focused ultrasound (HIFU) treatments. The objective of this clinical study was to evaluate the reliability of our system in assessing the volume of HIFU lesions in the prostate, using a comparison with magnetic resonance imaging (MRI). Elastograms were obtained in 20 patients after HIFU treatment for prostate cancer and gadolinium-enhanced T1- and T2-weighted MRI was performed. Lesion boundaries were manually outlined and the volume was calculated. A statistically significant correlation of rho = 0.62 (p = 0.022) was found between elastographic and MRI measurements of lesion volume, with elastographic measurements that generally underestimated the volume measured in MRI. Some basic physics (hypoechoic areas) and instrumentation (frame rate and band width) issues that were detrimental to image quality in vivo are reported, along with propositions to improve the technique. Because of these issues and, although good correspondence between elastographic and MRI measurements was found in some patients, elastographic measurements were unable to predict MRI measurements in a single individual. Nevertheless, the results confirmed the potential of elastography for monitoring HIFU treatment of the prostate. Further investigation will be conducted using better suited ultrasound equipment and performing real-time elastogram calculations.

Experimental evaluation of lesion prediction modelling in the presence of cavitation bubbles: intended for high-intensity focused ultrasound prostate treatment.

The accuracy of high-intensity focused ultrasound (HIFU) lesion prediction modelling was evaluated for a truncated spherical transducer designed for prostate cancer treatment The modelling adapted the bio heat transfer equation (BHTE) to take into account the activity of cavitation bubbles generated during HIFU exposure. This modelling was used to predict the lesions produced by three different transducer geometries: fixed-focus, concentric-ring and 1.5D phased-array. Lesions were predicted for different ultrasound exposure conditions close to those used in prostate cancer treatment. Twenty-one in vitro and nine in vitro experiments were performed on pig liver to validate the accuracy of the predictions. A good match was found between the predicted and experimental lesion shapes. Lesion dimensions (maximum depth and length, area at the centre of the lesion or central surface area) were measured on experimental and predicted lesions. The central surface area was predicted by the model with a range of error of 0.15-6.5% for in vitro tests and 0.97-9% in vivo. For comparison, BHTE without bubbles had a range of error of 0.4-55.5% (in vitro) and 9-25.5% (in vivo). The model should be accurate enough to predict HIFU lesions under ultrasound exposure conditions used in prostate cancer treatment.

[High intensity focused ultrasonic destruction of hepatic parenchyma]. / Destruction de parenchyme hépatique par ultrasons focalisés.

OBJECTIVE: High intensity focused ultrasound (HIFU) is an effective and precise method of focal tumoral destruction since it is associated with imagery. This method is widespread for the endorectal treatment of prostatic adenocarcinomas. HIFU seem appropriate for the treatment of liver tumors but its use needs to be experimentally tested in vivo. The aim of the work is to study the feasibility, tolerance and effectiveness of the destruction of porcine liver by HIFU. MATERIAL AND METHODS: Ten pigs had liver destruction by HIFU after coeliotomy. Four to 5 2,3 cm(3) HIFU lesions were performed per animal under ultrasonographic control. The study included biological surveillance and an autopsy was performed 4 to 24 hours later for histological examination of the liver. RESULTS: The destruction of the liver was feasible in all cases and the 4 lobes of the liver could be treated. The general and biological tolerance of the procedure was excellent. Ultrasonographic features of the HIFU lesions were defined. The histological examination of the lesions showed well-circumscribed necrosis areas associated with cavitation or histological deficiencies of various degrees. CONCLUSION: This work demonstrated that liver destruction by HIFU is a feasible and effective method with low morbidity. A long-term experimental study is necessary before comtemplating its clinical use.

1.5-D high intensity focused ultrasound array for non-invasive prostate cancer surgery.

The aim of this study is to demonstrate the feasibility of a new spherically curved 1.5-D phased array for the treatment of localized prostatic cancer. The device is designed to conform to the Ablatherm machine (EDAP-Technomed, France), a commercially available machine in which high intensity focused ultrasound (HIFU) treatment for prostate cancer is administered transrectally. It uses high intensity electronically focused ultrasound to steer a beam along two axes, allowing enough depth to be reached to treat large prostates and eliminating two degrees of mechanical movement. Through computer simulation, it was determined that a curved 1.5-D configuration offered the optimal design. Two configurations were then proposed, and their ability to steer a beam within a target volume centered on the geometric focus of the transducer was simulated. An eight-element prototype was constructed to test the piezo-composite material and its electro-acoustical efficiency. Then, an array was constructed, and a multi-channel amplifier and control system were added, to permit remote operation. Acoustical and electrical measurements were made to verify performance. Finally, the 1.5-D array was tested in vitro on samples of pig liver to confirm the ability to induce lesions.

France: a lawyer's view on female circumcision performed among immigrants.

PIP: Everyone agrees that female circumcision should not be done. Africans, however, have imported this custom to France. African parents who circumcise their children in France have been brought to court, since this is against the French Penal Code. People are shocked to see these parents being prosecuted, because, they are only following their cultural traditions. Innocent children must be defended against this cruel tradition. In 2 recent cases, the Criminal Court imposed sentences of 3 years imprisonment, suspended. In the future, penalties will probably be more severe. The Paris-based Group for the Abolition of Sexual Mutilation, which is affiliated with the Inter-African Committee, does information and sensitization work against female circumcision among French immigrants.^ieng