High-energy shockwaves and extracorporeal high-intensity focused ultrasound

Urinary outcomes of new ultra-minimally invasive treatments for prostate cancers

PURPOSE OF REVIEW

The aim of this narrative review is to evaluate the current available literature on urinary outcomes following cryotherapy and high-intensity focused ultrasound (HIFU) for localized prostate cancer (PCa).

RECENT FINDINGS

The available literature is heterogeneous in terms of intervention modalities and assessment of urinary outcome measures. Nevertheless, ultra-minimally invasive treatments seem to provide good urinary outcomes. Technological advancement and the adoption of more conservative ablation templates allow for a further reduction of toxicity and better preservation of urinary function. Urinary incontinence occurs in 0-10% of the patients and, is mostly transient. Voiding and storage lower urinary tract symptoms (LUTS) mostly occur in the early postoperative period and rarely require surgical treatment. Focal therapies performed with a salvage intent after external beam radiotherapy have a significantly higher impact on patient's urinary function.

SUMMARY

Ultra-minimally invasive treatment for PCa show a good safety profile concerning urinary function, but consensus on when and how best to assess this is still lacking. Efforts should be made to standardize the report of preoperative and postoperative urinary function to provide higher level of evidence.

Multivariable-incorporating super-resolution residual network for transcranial focused ultrasound simulation

BACKGROUND AND OBJECTIVE

Transcranial focused ultrasound (tFUS) has emerged as a new non-invasive brain stimulation (NIBS) modality, with its exquisite ability to reach deep brain areas at a high spatial resolution. Accurate placement of an acoustic focus to a target region of the brain is crucial during tFUS treatment; however, the distortion of acoustic wave propagation through the intact skull casts challenges. High-resolution numerical simulation allows for monitoring of the acoustic pressure field in the cranium but also demands extensive computational loads. In this study, we adopt a super-resolution residual network technique based on a deep convolution to enhance the prediction quality of the FUS acoustic pressure field in the targeted brain regions.

METHODS

The training dataset was acquired by numerical simulations performed at low-(1.0 mm) and high-resolutions (0.5mm) on three ex vivo human calvariae. Five different super-resolution (SR) network models were trained by using a multivariable dataset in 3D, which incorporated information on the acoustic pressure field, wave velocity, and localized skull computed tomography (CT) images.

RESULTS

The accuracy of 80.87±4.50% in predicting the focal volume with a substantial improvement of 86.91% in computational cost compared to the conventional high-resolution numerical simulation was achieved. The results suggest that the method can greatly reduce the simulation time without sacrificing accuracy and improve the accuracy further with the use of additional inputs.

CONCLUSIONS

In this research, we developed multivariable-incorporating SR neural networks for transcranial focused ultrasound simulation. Our super-resolution technique may contribute to promoting the safety and efficacy of tFUS-mediated NIBS by providing on-site feedback information on the intracranial pressure field to the operator.

Single-center, prospective phase 2 trial of high-intensity focused ultrasound (HIFU) in patients with unilateral localized prostate cancer: good functional results but oncologically not as safe as expected

PURPOSE

Focal therapy (FT) for localized prostate cancer (PCa) is only recommended within the context of clinical trials by international guidelines. We aimed to investigate oncological follow-up and safety data of focal high-intensity focused ultrasound (HIFU) treatment.

METHODS

We conducted a single-center prospective study of 29 patients with PCa treated with (focal) HIFU between 2016 and 2021. Inclusion criteria were unilateral PCa detected by mpMRI-US-fusion prostate biopsy and maximum prostate specific antigen (PSA) of 15 ng/ml. Follow-up included mpMRI-US fusion-re-biopsies 12 and 24 months after HIFU. No re-treatment of HIFU was allowed. The primary endpoint was failure-free survival (FFS), defined as freedom from intervention due to cancer progression.

RESULTS

Median follow-up of all patients was 23 months, median age was 67 years and median preoperative PSA was 6.8 ng/ml. One year after HIFU treatment PCa was still detected in 13/ 29 patients histologically (44.8%). Two years after HIFU another 7/29 patients (24.1%) were diagnosed with PCa. Until now, PCa recurrence was detected in 11/29 patients (37.93%) which represents an FFS rate of 62%.One patient developed local metastatic disease 2 years after focal HIFU. Adverse events (AE) were low with 70% of patients remaining with sufficient erectile function for intercourse and 97% reporting full maintenance of urinary continence.

CONCLUSION

HIFU treatment in carefully selected patients is feasible. However, HIFU was oncologically not as safe as expected because of progression rates of 37.93% and risk of progression towards metastatic disease. Thus, we stopped usage of HIFU in our department.

A Bone-Penetrating Precise Controllable Drug Release System Enables Localized Treatment of Osteoporotic Fracture Prevention via Modulating Osteoblast-Osteoclast Communication

Improving local bone mineral density (BMD) at fracture-prone sites of bone is a clinical concern for osteoporotic fracture prevention. In this study, a featured radial extracorporeal shock wave (rESW) responsive nano-drug delivery system (NDDS) is developed for local treatment. Based on a mechanic simulation, a sequence of hollow zoledronic acid (ZOL)-contained nanoparticles (HZNs) with controllable shell thickness that predicts various mechanical responsive properties is constructed by controlling the deposition time of ZOL and Ca²⁺ on liposome templates. Attributed to the controllable shell thickness, the fragmentation of HZNs and the release of ZOL and Ca²⁺ can be precisely controlled with the intervention of rESW. Furthermore, the distinct effect of HZNs with different shell thicknesses on bone metabolism after fragmentation is verified. In vitro co-culture experiments demonstrate that although HZN2 does not have the strongest osteoclasts inhibitory effect, the best pro-osteoblasts mineralization results are achieved via maintaining osteoblast-osteoclast (OB-OC) communication. In vivo, the HZN2 group also shows the strongest local BMD enhancement after rESW intervention and significantly improves bone-related parameters and mechanical properties in the ovariectomy (OVX)-induced osteoporosis (OP) rats. These findings suggest that an adjustable and precise rESW-responsive NDDS can effectively improve local BMD in OP therapy.

Salvage Radiotherapy Plus Androgen Deprivation Therapy for High-Risk Prostate Cancer with Biochemical Failure after High-Intensity Focused Ultrasound as Primary Treatment

We conduct a retrospective analysis of salvage radiotherapy plus androgen deprivation therapy (SRT+ADT) for high-risk prostate cancer patients with biochemical failure after high-intensity focused ultrasound (HIFU) as the primary treatment. A total of 38 patients, who met the criteria of biochemical failure and were consecutively treated with SRT+ADT, were enrolled. All patients received intensity modulated radiotherapy with a median dose of 70 Gy to the clinical target volume. ADT was given before, during or after the course of SRT with the duration of ≦6 months (n = 14), 6−12 months (n = 12) or >12 months (n = 12). The median follow-up was 45.9 months. A total of 10 (26.3%) patients had biochemical failure after SRT+ADT. The cumulative 5-year biochemical progression free survival (b-PFS) and overall survival (OS) rate was 73.0% and 80.3%, respectively. A nadir prostate-specific antigen (nPSA) value 0.02 ng/mL was observed to predict the b-PFS in multivariate analysis. The 5-year b-PFS was 81.6% for those with nPSA < 0.02 compared with 25.0% with nPSA ≧ 0.02. The adverse effects related to SRT+ADT were mild in most cases and only three (8%) patients experienced grade 3 urinary toxicities. For high-risk prostate cancer after HIFU as primary treatment with biochemical failure, our study confirms the feasibility of SRT+ADT with high b-PFS, OS and low toxicity.

[MRI-guided minimally invasive treatment of prostate cancer]

CLINICAL/METHODOLOGICAL ISSUE

Multiparametric magnetic resonance imaging (mpMRI) of the prostate plays a crucial role in the diagnosis and local staging of primary prostate cancer.

STANDARD RADIOLOGICAL METHODS

Image-guided biopsy techniques such as MRI-ultrasound fusion not only allow guidance for targeted tissue sampling of index lesions for diagnostic confirmation, but also improve the detection of clinically significant prostate cancer.

METHODOLOGICAL INNOVATIONS

Minimally invasive, focal therapies of localized prostate cancer complement the treatment spectrum, especially for low- and intermediate-risk patients.

PERFORMANCE

In patients of low and intermediate risk, MR-guided, minimally invasive therapies could enable local tumor control, improved functional outcomes and possible subsequent therapy escalation. Further study results related to multimodal approaches and the application of artificial intelligence (AI) by machine and deep learning algorithms will help to leverage the full potential of focal therapies for prostate cancer in the upcoming era of precision medicine.

ACHIEVEMENTS

Completion of ongoing randomized trials comparing each minimally invasive therapy approach with established whole-gland procedures is needed before minimally invasive therapies can be implemented into existing treatment guidelines.

PRACTICAL RECOMMENDATIONS

This review article highlights minimally invasive therapies of prostate cancer and the key role of mpMRI for planning and conducting these therapies.

Cohort study of high-intensity focused ultrasound in the treatment of localised prostate cancer treatment: Medium-term results from a single centre

We report medium-term results in men receiving primary whole-gland HIFU (WG-HIFU) and following salvage treatment. One hundred and twenty-eight patients in a single hospital were enrolled. The enrolled patients were treated with WG-HIFU for primary localized prostate cancer. Salvage treatment include androgen deprivation therapy, secondary HIFU and salvage radiation therapy. Our primary outcomes were biochemical recurrence–free survival, salvage treatment–free survival, and metastasis-free survival. Secondary outcomes included urinary incontinence, de novo erectile dysfunction, acute epididymitis, bladder neck contracture, and urethral stricture. The 5-year biochemical recurrence–free survival rates were 85.7%, 82.7%, and 45.2% for D’Amico low-, intermediate-, and high-risk groups, respectively. Multivariate analysis revealed high risk group is the only predictor of significant shorter biochemical recurrence free survival, salvage treatment free survival, and metastasis free survival. Of 38 patients receiving salvage treatment after biochemical recurrence, 29 (76.3%) became free from biochemical recurrence. Rates of the adverse events of urinary incontinence, acute epididymitis, bladder neck contracture or urethral stricture, and de novo erectile dysfunction were 2.3%, 10.9%, 20.3%, 65.6%, respectively. In conclusion, WG-HIFU is an effective treatment option for localised prostate cancer, especially in D’Amico low- and intermediate-risk cases. The success rate of salvage treatment with radiation therapy and secondary HIFU for biochemical recurrence was acceptable. Fewer adverse events were caused by HIFU, especially incontinence and erectile dysfunction, than by radical prostatectomy and radiotherapy.

Post-HIFU locally relapsed prostate cancer: high-dose salvage radiotherapy guided by molecular imaging

PURPOSE

To evaluate tolerance and biochemical control rates of salvage external beam radiotherapy (EBRT) in patients with local relapse from prostate cancer (PC) after high-intensity focused ultrasound (HIFU) as primary treatment.

METHODS

Twenty-four patients presented biochemical failure of PC. Salvage EBRT to the residual prostate was performed with moderate hypofractionation schedule (MHRT) in 28 fractions (n = 16) or with extreme hypofractionation schedule (SBRT) in 5 fractions (n = 8) by means of image-guided volumetric modulation arc therapy. In case of MHRT, the median dose was 71.4 Gy, whereas in case of SBRT it was 32.5 Gy.

RESULTS

The median follow-up was 28 months. The median PSA nadir was 0.26 ng/mL. In case of MHRT, the median PSA nadir was 0.15 ng/mL and occurred within a median time of 19 months. In case of SBRT, the median PSA nadir was 0.64 ng/mL and occurred within a median time of 8 months. No G3 higher acute or late toxicity after EBRT was observed. Only three patients presented with G2 acute GI toxicity (actinic proctitis). Twelve patients experienced acute G1 GU toxicity: 8/16 of men treated with MHRT and 4/8 of men treated with SBRT. Complete local control of disease was achieved in 23/24 patients (96%).

CONCLUSIONS

Our data confirm the feasibility and the low toxicity of salvage EBRT with both schedules of treatment after HIFU failure. The findings of low acute toxicity and good biochemical control rates are encouraging, but a larger number of patients and a longer follow-up are needed to confirm these results.

Recurrence of prostate cancer after HIFU. Proposal of a novel predictive index

Background and aim of the work: Prostate cancer is one of the most common cancers in men over 50 years of age. Surgery, radiotherapy and hormonal manipulation represent its typical treatment. High-Intensity Focused Ultrasound (HIFU) is an alternative choice in localized prostate cancer. To date, an index for prediction of recurrence in patients treated with HIFU is not availabe. Our study proposes a novel index for the predition of recurrence able to determine if a candidate is fit for this tratment. methods: 107 patients underwent HIFU fram 2010 to 2015. A total of 12 variables were considered for the analysis. The final predictive model was obtained through a stepwise forward selection method. Results: The final model used a total of 6 variables, all correlated to the response variable. The Index is able to predict the recurrence after HIFU tratment in the most majority of candidates to treatment. The index may be used to make a more scientific decision with regard to choosing optimal candidates for HIFU. (www.actabiomedica.it)

Primary whole-gland ablation for localized prostate cancer with high-intensity focused ultrasound: The important predictors of biochemical recurrence

OBJECTIVES

To identify predictive factors of biochemical recurrence for patients undergoing high-intensity focused ultrasound treatment for localized prostate cancer.

METHODS

We retrospectively identified patients receiving whole-gland prostate ablation with high-intensity focused ultrasound for localized prostate cancer from 2009 to 2015. All the patients received pre-high-intensity focused ultrasound radical transurethral resection of the prostate. We included perioperative parameters as follows: age, preoperative prostate volume, stage of operation, initial prostate-specific antigen, T stage, postoperative prostate-specific antigen nadir, Gleason score, time to prostate-specific antigen nadir and the presence of prostate-specific antigen biochemical recurrence. Multivariable Cox regression and Kaplan-Meier analysis were used for investigating predictors of recurrence, and receiver operating characteristic analysis was used for the cut-off values of prostate-specific antigen nadir.

RESULTS

Among 182 patients, 26.9% had prostate-specific antigen biochemical recurrence after high-intensity focused ultrasound during the median follow-up period of 32.21 months. Gleason score ≥7 (Gleason score 7, hazard ratio 2.877, P = 0.027), stage ≥T2b (T2b, hazard ratio 3.16, P = 0.027) and prostate-specific antigen nadir (hazard ratio 1.11, P < 0.001) were statistically significant, whereas there was no significance in prostate volume and initial prostate-specific antigen. We posit that a cut-off level of prostate-specific antigen nadir 0.43 ng/mL might be considered as an independent predictive factor for prostate-specific antigen biochemical recurrence in high-intensity focused ultrasound patients in multivariate analysis (P < 0.001, hazard ratio 7.39, 95% confidence interval 3.56-15.37), and created a new nadir-related prediction model for biochemical recurrence prediction.

CONCLUSIONS

Postoperative prostate-specific antigen nadir of 0.43 ng/mL can be considered an important predictive factor for biochemical recurrence in primary whole-prostate gland high-intensity focused ultrasound treatment, and the nadir-related prediction model might provide a reference for early salvage treatment. Furthermore, Gleason score ≥7, stage ≥T2b might be associated with unfavorable outcomes, although prostate volume and higher initial prostate-specific antigen appear not to be associated with biochemical recurrence for the high-intensity focused ultrasound treatment.

Multi-resolution simulation of focused ultrasound propagation through ovine skull from a single-element transducer

Transcranial focused ultrasound (tFUS) is emerging as a non-invasive brain stimulation modality. Complicated interactions between acoustic pressure waves and osseous tissue introduce many challenges in the accurate targeting of an acoustic focus through the cranium. Image-guidance accompanied by a numerical simulation is desired to predict the intracranial acoustic propagation through the skull; however, such simulations typically demand heavy computation, which warrants an expedited processing method to provide on-site feedback for the user in guiding the acoustic focus to a particular brain region. In this paper, we present a multi-resolution simulation method based on the finite-difference time-domain formulation to model the transcranial propagation of acoustic waves from a single-element transducer (250 kHz). The multi-resolution approach improved computational efficiency by providing the flexibility in adjusting the spatial resolution. The simulation was also accelerated by utilizing parallelized computation through the graphic processing unit. To evaluate the accuracy of the method, we measured the actual acoustic fields through ex vivo sheep skulls with different sonication incident angles. The measured acoustic fields were compared to the simulation results in terms of focal location, dimensions, and pressure levels. The computational efficiency of the presented method was also assessed by comparing simulation speeds at various combinations of resolution grid settings. The multi-resolution grids consisting of 0.5 and 1.0 mm resolutions gave acceptable accuracy (under 3 mm in terms of focal position and dimension, less than 5% difference in peak pressure ratio) with a speed compatible with semi real-time user feedback (within 30 s). The proposed multi-resolution approach may serve as a novel tool for simulation-based guidance for tFUS applications.

Quality of life and functional outcome after infravesical desobstruction and HIFU treatment for localized prostate cancer

Background

To evaluate quality of life, functional and oncological outcome after infravesical desobstruction and HIFU treatment for localized prostate cancer.

Methods

One hundred thirty-one patients, treated with TURP and HIFU in a single institution were followed up for oncological and functional outcome. Oncological outcome was quantified by biochemical recurrence free survival using the Stuttgart and Phoenix criteria. Quality of life was assessed by usage of standardized QLQ-C30 and QLQ-PR25 questionnaires. In addition, functional questionnaires such as IPSS and IIEF-5 were used. Complications were assessed by the Clavien-Dindo classification.

Results

One hundred thirty-one patients with a mean age of 72.8 years (SD: 6.0) underwent HIFU for prostate cancer (29.0% low risk, 58.8% intermediate risk, 12.2% high risk). PSA nadir was 0.6 ng/ml (SD: 1.2) after a mean of 4.6 months (SD: 5.7). Biochemical recurrence free survival defined by Stuttgart criteria was 73.7%, 84.4% and 62.5% for low-, intermediate- and high-risk patients after 22.2 months. Complications were grouped according to Clavien-Dindo and occurred in 10.7% (grade II) and 11.5% (grade IIIa) of cases. 35.1% of patients needed further treatment for bladder neck stricture. Regarding incontinence, 14.3%, 2.9% and 0% of patients had de novo urinary incontinence grade I°, II° and III° and 3.8% urge incontinence due to HIFU treatment. Patients were asked for the ability to have intercourse: 15.8%, 58.6% and 66.7% of patients after non-, onesided and bothsided nervesparing procedure were able to obtain sufficient erection for intercourse, respectively. Regarding quality of life, mean global health score according to QLQ-C30 was 69.4%.

Conclusion

HIFU treatment for localized prostate cancer shows acceptable oncological safety. Quality of life after HIFU is better than in the general population and ranges within those of standard treatment options compared to literature. HIFU seems a safe valuable treatment alternative for patients not suitable for standard treatment.

The Application of Clinical Lithotripter Shock Waves to RNA Nucleotide Delivery to Cells

The delivery of genes into cells through the transfer of ribonucleic acids (RNAs) has been found to cause a change in the level of target protein expression. RNA-based transfection is conceptually more efficient than commonly delivered plasmid DNA because it does not require division or damage of the nuclear envelope, thereby increasing the chances of the cell remaining viable. Shock waves (SWs) have been found to induce cellular uptake by transiently altering the permeability of the plasma membrane, thereby overcoming a critical step in gene therapy. However, accompanying SW bio-effects include dose-dependent irreversible cell injury and cytotoxicity. Here, the effect of SWs generated by a clinical lithotripter on the viability and permeabilisation of three different cell lines in vitro was investigated. Comparison of RNA stability before and after SW exposure revealed no statistically significant difference. Optimal SW exposure parameters were identified to minimise cell death and maximise permeabilisation, and applied to enhanced green fluorescent protein (eGFP) messenger RNA (mRNA) or anti-eGFP small interfering RNA delivery. As a result, eGFP mRNA expression levels increased up to 52-fold in CT26 cells, whereas a 2-fold decrease in GFP expression was achieved after anti-eGFP small interfering RNA delivery to MCF-7/GFP cells. These results indicate that SW parameters can be employed to achieve effective nucleotide delivery, laying the foundation for non-invasive and high-tolerability RNA-based gene therapy.

Diagnostic and Therapeutic Strategies for Prostate Cancer

Prostate cancer (PC) is a major disease that affects men's health worldwide. It is the second most common form of cancer in men, surpassed only by nonmelanoma skin cancers such as basal and squamous cell carcinomas. Diagnostic strategies with population screening for prostate cancer using prostate-specific antigen (PSA) has been surrounded with controversy and debated intensively ever since the PSA protein was first purified in 1979 by Wang et al. At the same time, advances in diagnostic imaging, surgery, radiation, and chemotherapy have increased the opportunity to effectively diagnose, treat, and manage PC. Given the sheer burden of PC disease in Denmark and worldwide, new and innovative strategies for cancer diagnosis and care are needed. This article is a short review of current diagnostic and therapeutic strategies for the care and management of prostate cancer in Denmark.

The Effects of Focal Therapy for Prostate Cancer on Sexual Function: A Combined Analysis of Three Prospective Trials

BACKGROUND

Tissue preservation by means of focal therapy offers some men with clinically significant prostate cancer an alternative to standard care that appears to confer favourable genito-urinary outcomes. The precise estimates of these outcomes have so far been based on small series.

OBJECTIVE

This analysis pools the sexual domain related patient reported outcomes from three prospective, registered studies that represent a range of inclusion criteria.

DESIGN, SETTING, AND PARTICIPANTS

One-hundred and eighteen men with localised prostate cancer (prostate specific antigen ≤ 15ng/ml, Gleason ≤ 4+3, stage ≤ T3aN0M0) treated in a tissue-preserving manner using high intensity focused ultrasound from three registered studies were included. Data on International Index of Erectile Function (IIEF-5) scores and use of phosphodiesterase-5-inhibitors were collected at baseline, and 1 mo, 3 mo, 6 mo, 9 mo, and 12 mo postoperatively. The IIEF-15 total and individual domain scores were used to assess overall sexual function. Urinary function was assessed with the International Prostate Symptom Score (IPSS), IPSS quality-of-life, and UCLA-Expanded Prostate Cancer Index Composite continence questionnaires. General health status was derived by means of the Charlson score. Multiple linear regression was used to assess whether age, grade, stage, qualitative scores (IIEF, IPSS, Expanded Prostate Cancer Index Composite, Charlson), or focal therapy type duration were associated with IIEF-5 and IIEF-15 scores at 12 mo.

RESULTS AND LIMITATIONS

Median age was 63 yr (interquartile range [IQR] 52-70 yr). Median IIEF-erectile score at baseline was 23 (IQR 11-28). This declined significantly to 9 (IQR 3-22, p<0.01) at 1 mo, but improved to 20 (IQR 9-29, p=0.30) at 1 yr posttreatment. Changes in total IIEF and other IIEF domains were only significantly different from preoperative values at 1 mo and 3 mo postoperatively. In the same period, the proportion of men using phosphodiesterase-5-inhibitors was 10% preoperatively, reaching 43% and 42% at 6 mo and 9 months before declining to 37% at 1 yr. The only baseline determinants of postoperative erectile function were total IIEF and IIEF-erectile function scores (p=0.002). The primary limitation of our study is the relatively short follow-up of 1 yr.

CONCLUSION

Men who received a range of tissue preserving therapies from the three pertinent studies experienced small decreases in total IIEF, erectile, and individual sexual domain scores that are not significantly different to those recorded at baseline. The only determinant of erectile dysfunction after tissue preserving therapy was preoperative erectile dysfunction status. Tissue preservation confers a high probability of maintaining erectile function that appears independent of all perioperative factors with the exception of baseline status.

PATIENT SUMMARY

In this report, the largest prospectively collected and published set of patients with erectile dysfunction outcomes post-focal therapy for prostate cancer, we have found a return to baseline International Index of Erectile Function-erectile and total International Index of Erectile Function scores by 6 mo post-focal therapy which was maintained at 1 yr, with the majority of patients not on any form of medical treatment for their erectile dysfunction at that point. Focal therapy may represent a suitable alternative for men of any age or comorbidity wishing to maintain erectile function.

Systematic Review of the Efficacy and Safety of High-intensity Focussed Ultrasound for Localised Prostate Cancer

CONTEXT

High-intensity focussed ultrasound (HIFU) has been used for 10 yr to treat localised prostate cancer (PCa).

OBJECTIVE

To evaluate systematically the evidence on the efficacy and side effects of HIFU in the primary treatment of localised PCa.

EVIDENCE ACQUISITION

We performed a critical review and appraisal of Medline (Ovid), PreMedline, Embase, and Cochrane Database of Systematic Reviews publications on HIFU up to May 2013. One systematic review and 18 primary studies, all case series, were eligible.

EVIDENCE SYNTHESIS

Outcomes were summarised and evidence was evaluated using Grading of Recommendations, Assessment, Development and Evaluation methodology. Low-quality evidence suggests an overall survival rate after Ablatherm HIFU ranging from 80% to 89% for >5 yr. The PCa survival rate ranges from 97% to 99% for >5 yr. Effect of HIFU on quality of life remains undetermined. Erectile dysfunction was the most frequent adverse event reported from zero but up to 74% of patients. Adverse events affecting the urinary tract occurred in 0.7-31% of patients, bladder outlet obstruction in 4-51.5%, and they were more frequent in patients who had transurethral resection of the prostate the same day or within 2 d of HIFU. Outcomes vary for low- and high-risk categories.

CONCLUSIONS

Good quality evidence on the efficacy of HIFU treatment for localised PCa is lacking.

PATIENT SUMMARY

We reviewed all the data on treatment with high-intensity focussed ultrasound (HIFU) for localised prostate cancer (PCa). The quality of the evidence is very low because the information is based on a series of patients who received HIFU treatment with no comparison with active surveillance or radical treatment. Case series suggest an overall survival rate up to 89% and a PCa survival rate up to 99% after 5 yr, but these numbers vary according to the patient's risk category. Longer term and effects on quality of life are unknown.

Three-axis MR-conditional robot for high-intensity focused ultrasound for treating prostate diseases transrectally

BACKGROUND

A prototype magnetic resonance image (MRI)-conditional robot was developed for navigating a high-intensity focused ultrasound (HIFU) system in order to treat prostate cancer transrectally.

MATERIALS AND METHODS

The developed robotic device utilizes three PC-controlled axes: a linear axis for motion along the rectum, an angular axis for rotation in the rectum, and a linear axis to lift the robot up and down. Experiments with the system were performed in a 1.5-T MRI system using gel phantoms.

RESULT

The robot was successfully operated in a 1.5-T clinical MRI system. The effect of piezoelectric motors and optical encoders was quantified based on the reduction of signal to noise ratio. Discrete and overlapping lesions were created accurately by moving the HIFU transducer with the robotic device.

CONCLUSION

An MRI-conditional HIFU robot was developed which can create controlled thermal lesions under MRI guidance. The intention is to use this robot transrectally in the future for the treatment of prostate cancer.

Removing atherosclerotic plaque created using high cholesterol diet in rabbit using ultrasound

Background

The aim of the proposed study was to conduct a feasibility study using a flat rectangular (3 × 10 mm²) transducer operating at 5 MHz for removing atherosclerotic plaque in an in vivo model. The proposed method can be used in the future for treating atherosclerotic plaques in humans.

Methods and results

The plaque in the rabbits was created using high cholesterol diet for 4 months. The amount of plaque removed was studied as a function of intensity, with a fixed pulse repetition frequency (PRF), and duty factor (DF).

Conclusions

The amount of plaque removed is directly related to the acoustic intensity. It was found that the presence of bubbles accelerates the removal of plaque. In order to ensure that pure mechanical mode ultrasound was used, the intensity used does not produce temperatures that exceed 1°C.

Correlation of pretreatment clinical parameters and PSA nadir after high-intensity focused ultrasound (HIFU) for localised prostate cancer

OBJECTIVE

To determine which pretreatment clinical parameters were predictive of a low prostate-specific antigen (PSA) nadir following high-intensity focused ultrasound (HIFU) treatment.

PATIENTS AND METHODS

Retrospective study of patients with clinically localised prostate cancer undergoing HIFU at a single centre between December 1997 and September 2009. Whole-gland treatment was applied. Patients also included if they had previously undergone transurethral resection of the prostate (TURP). TURP was also conducted simultaneously to HIFU. Biochemical failure based on Phoenix definition (PSA nadir + 2). Univariate and multivariate analysis of pretreatment clinical parameters conducted to assess those factors predictive of a PSA nadir ≤0.2 and >0.2 ng/ml.

RESULTS

Mean (SD) follow-up was 6.2 (2.8) years; median (range) was 6.3 (1.1-12.2) years. Kaplan-Meier estimate of biochemical disease-free survival rate at 8 years was 83 and 48 % for patients achieving a PSA nadir of ≤0.2 and >0.2 ng/ml, respectively. Prostate volume and incidental finding of cancer were significant predictors of low PSA nadir (≤0.2 ng/ml).

CONCLUSIONS

Prostate volume and incidental finding of cancer could be predictors for oncologic success of HIFU based on post-treatment PSA nadir.

Conservative treatment of a recto-urethral fistula due to salvage HIFU for local recurrence of prostate cancer, 5 years after radical prostatectomy and external beam radiotherapy

Recto-urethral fistula is one of the most serious complications caused by high-intensity-focused ultrasound used as salvage treatment for recurrence of prostate cancer after brachytherapy or external beam radiotherapy (EBRT). We report the case of a recto-urethral fistula in a 68-year-old patient, who previously had undergone radical prostatectomy and EBRT for prostate cancer (pT3 N0 Mx). The fistula was treated conservatively by an indwelling Foley catheter, without the creation of an intestinal diversion. The fistula was assessed initially by a retrograde and a CT scan of the pelvis with contrast medium and reassessed periodically by means of retrograde urethrograms. To date, 24 months after this episode, no evidence of recurrence of the fistula has been found.

Utility of immunohistochemistry markers in the interpretation of post-high-intensive focussed ultrasound prostate biopsy cores

PURPOSE

To overcome the difficulties in the interpretation of postoperative tumor obtaining biopsy cores for patients who treated their prostate cancer with high-intensity focussed ultrasound (HIFU) therapy.

METHODS

The H&E slides of 58 patients with residual prostate cancer after HIFU treatment were systematically reviewed. Correlation between the pathologist's findings and immunohistochemical expression of MIB-1, alpha-Methyl-Co-Racemase and 34βE-12 staining was analyzed.

RESULTS

Mean time from treatment to biopsy was 40.2 (8-208) weeks. The expert review of the H&E slides identified 40 patients with viable carcinoma in the post-HIFU biopsy cores. 18 patients were revised to necrosis-only-tumors. These biopsies were performed not later than 16 weeks after HIFU treatment (median 10.9 weeks, range 8-14). Both MIB-1 and AMACR staining displayed significant differential expression in viable carcinoma (p < 0.001) compared to necrosis tumors. Referring to viable carcinoma tissue, AMACR staining index was significantly rising, the longer treatment dated back from biopsy (p < 0.002). In this context, 34-β-E12 stained negative through all tumor areas and positive in the majority (85%) of the surrounding non-neoplastic epithelium.

CONCLUSIONS

AMACR and MIB-1 reliably differentiate viable carcinoma from a process of ongoing irreversible necrosis in early post-HIFU prostate biopsy cores and therefore proposed-in addition with 34 beta-E12-as useful markers exposing suspicious tumor foci in difficult cases.

Sonoporation mediated immunogene therapy of solid tumors

Development of gene-based therapies for the treatment of inherited and acquired diseases, including cancer, has seen renewed interest in the use of nonviral vectors coupled to physical delivery modalities. Low-frequency ultrasound (US), with a well-established record in a clinical setting, has the potential to deliver DNA efficiently, accurately and safely. Optimal in vivo parameters for US-mediated delivery of naked plasmid DNA were established using the firefly luciferase reporter gene construct. Optimized parameters were used to administer a therapeutic gene construct, coding for granulocyte-macrophage colony-stimulating factor (GM-CSF) and B7-1 costimulatory molecule, to growing murine fibrosarcoma tumors. Tumor progression and animal survival was monitored throughout the study and the efficacy of the US-mediated gene therapy determined and compared with an electroporation-based approach. Optimal parameters for US-mediated delivery of plasmid DNA to tumors were deduced to be 1.0 W/cm(2) at 20% duty cycle for 5 min (60 J/cm(2)). In vivo US-mediated gene therapy resulted in a 55% cure rate in tumor-bearing animals. The immunological response invoked was cell mediated, conferring resistance against re-challenge and resistance to tumor challenge after transfer of splenocytes to naïve animals. US treatment was noninjurious to treated tissue, whereas therapeutic efficacy was comparable to an electroporation-based approach. US-mediated delivery of an immune-gene construct to growing tumors was therapeutically effective. Sonoporation has the potential to be a major factor in the development of nonviral gene delivery approaches.

One-step electrohydrodynamic production of drug-loaded micro- and nanoparticles

The objective of this work was to produce drug-loaded nanometre- and micrometre-scale particles using a single-step process that provides control over particle size and size distribution. Co-axial electrohydrodynamic processing was used, at ambient temperature and pressure, with poly(lactic-co-glycolic acid) as the polymeric coating material and oestradiol as the encapsulated drug. The particle diameter was varied from less than 120 nm to a few micrometres, by simple methodical adjustments in the processing parameters (polymer concentration and applied voltage). In vitro studies were performed to determine the drug release profile from the particles during unassisted and ultrasound-stimulated degradation in simulated body fluid. An encapsulation efficiency of approximately 70% was achieved and release of the drug was sustained for a period of over 20 days. Exposing the particles to ultrasound (22.5 kHz) increased the rate of release by approximately 8 per cent. This processing method offers several advantages over conventional emulsification techniques for the preparation of drug-loaded particles. Most significantly, process efficiency and the drug's functionality are preserved, as complex multistep processing involving harsh solvents, other additives and elevated temperatures or pressures are avoided. Production rates of 10(12) particles min(-1) can be achieved with a single pair of co-axial needles and the process is amenable to being scaled up by using multiple sets.

New treatments for localized prostate cancer

Interest in focal therapy for prostate cancer has recently been renewed owing to downward stage migration, improved biopsy and imaging techniques, and the prevalence of either unifocal cancer or a dominant cancer with secondary tumors of minimal malignant potential. Several techniques have potential for focal ablation of prostate cancer. Cryotherapy has been used for some time as primary therapy for complete ablation of the prostate or local recurrence after radiotherapy. Enthusiasm for cryotherapy as the primary therapy has been tempered by the uncertainty about complete ablation of the cancer, the frequent persistence of measurable prostate-specific antigen levels after the procedure, and a high rate of erectile dysfunction. Studies have reported "focal ablation" of prostate cancer with cryotherapy, targeting 1 side of the gland to eliminate a cancer confined to that side with less risk of urinary or sexual complications. Whether cryotherapy has sufficient power to eradicate focal cancer and can be targeted with sufficient accuracy to avoid damage to surrounding structures remains to be demonstrated in prospective clinical trials. High-intensity focused ultrasound (HIFU) has been used widely in Europe for complete ablation of the prostate, especially in elderly men who are unwilling or unable to undergo radical therapy. For low- or intermediate-risk cancer, the short- and intermediate-term oncologic results have been acceptable but need confirmation in prospective multicenter trials presently underway. Whole gland therapy with transrectal ultrasound guidance has been associated with a high risk of acute urinary symptoms, often requiring transurethral resection before or after HIFU. Adverse effects on erectile function seem likely after a therapy that depends on heat to eradicate the cancer, but erectile function after HIFU has not been adequately documented with patient-reported questionnaires. HIFU holds promise for focal ablation of prostate cancer. As with cryotherapy, focal HIFU should reduce the adverse sexual, urinary, and bowel effects of whole gland ablation. New techniques are being developed to allow HIFU treatment under real-time guidance using magnetic resonance imaging, which could improve the precision and reduce the adverse effects further. Another promising technique, currently in clinical trials, is vascular-targeted photodynamic therapy, which has been used for whole gland ablation of locally recurrent cancer after radiotherapy and, more recently, for focal ablation of previously untreated cancer. In combination with a new, systemically administered photodynamic agent, laser light is delivered through fibers introduced into the prostate under ultrasound guidance. This technique does not heat the prostate but destroys the endothelial cells and cancer by activating the photodynamic agent. Damage to surrounding structures appears to be limited and can be controlled by the duration and intensity of the light. We have reviewed the principles of focal therapy and these new therapeutic modalities.

High intensity focused ultrasound: physical principles and devices

High intensity focused ultrasound (HIFU) is gaining rapid clinical acceptance as a treatment modality enabling non-invasive tissue heating and ablation for numerous applications. HIFU treatments are usually carried out in a single session, often as a day case procedure, with the patient either fully conscious, lightly sedated or under light general anaesthesia. A major advantage of HIFU over other thermal ablation techniques is that there is no necessity for the transcutaneous insertion of probes into the target tissue. The high powered focused beams employed are generated from sources placed either outside the body (for treatment of tumours of the liver, kidney, breast, uterus, pancreas and bone) or in the rectum (for treatment of the prostate), and are designed to enable rapid heating of a target tissue volume, while leaving tissue in the ultrasound propagation path relatively unaffected. Given the wide-ranging applicability of HIFU, numerous extra-corporeal, transrectal and interstitial devices have been designed to optimise application-specific treatment delivery. Their principle of operation is described here, alongside an overview of the physical mechanisms governing HIFU propagation and HIFU-induced heating. Present methods of characterising HIFU fields and of quantifying HIFU exposure and its associated effects are also addressed.

Pressure-dependent effect of shock waves on rat brain: induction of neuronal apoptosis mediated by a caspase-dependent pathway

OBJECT

Shock waves have been experimentally applied to various neurosurgical treatments including fragmentation of cerebral emboli, perforation of cyst walls or tissue, and delivery of drugs into cells. Nevertheless, the application of shock waves to clinical neurosurgery remains challenging because the threshold for shock wave-induced brain injury has not been determined. The authors investigated the pressure-dependent effect of shock waves on histological changes of rat brain, focusing especially on apoptosis.

METHODS

Adult male rats were exposed to a single shot of shock waves (produced by silver azide explosion) at overpressures of 1 or 10 MPa after craniotomy. Histological changes were evaluated sequentially by H & E staining and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling (TUNEL). The expression of active caspase-3 and the effect of the nonselective caspase inhibitor N-benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone (Z-VAD-FMK) were examined to evaluate the contribution of a caspase-dependent pathway to shock wave-induced brain injury. High-overpressure (> 10 MPa) shock wave exposure resulted in contusional hemorrhage associated with a significant increase in TUNEL-positive neurons exhibiting chromatin condensation, nuclear segmentation, and apoptotic bodies. The maximum increase was seen at 24 hours after shock wave application. Low-overpressure (1 MPa) shock wave exposure resulted in spindle-shaped changes in neurons and elongation of nuclei without marked neuronal injury. The administration of Z-VAD-FMK significantly reduced the number of TUNEL-positive cells observed 24 hours after high-overpressure shock wave exposure (p < 0.01). A significant increase in the cytosolic expression of active caspase-3 was evident 24 hours after high-overpressure shock wave application; this increase was prevented by Z-VAD-FMK administration. Double immunofluorescence staining showed that TUNEL-positive cells were exclusively neurons.

CONCLUSIONS

The threshold for shock wave-induced brain injury is speculated to be under 1 MPa, a level that is lower than the threshold for other organs. High-overpressure shock wave exposure results in brain injury, including neuronal apoptosis mediated by a caspase-dependent pathway. This is the first report in which the pressure-dependent effect of shock wave on the histological characteristics of brain tissue is demonstrated.

Newer Modalities of Ultrasound Imaging and Treatment of the Prostate

Gray-scale ultrasound is widely used for assessing BPH and for obtaining prostate biopsies. However, it has limited value for evaluating cancer in the prostate. To improve ultrasound as an imaging modality of the prostate, many new technologies, such as color and power Doppler, 3-dimensional ultrasound of the prostate, and contrast-enhanced ultrasound have been developed. In addition, treatment modalities using ultrasound for the treatment of BPH have been developed. This review presents the recent developments in ultrasound of the prostate.

Extracorporeal high intensity focused ultrasound in the treatment of patients with solid malignancy

The ideal treatment of localized cancer should cause the complete death of tumor cells without damage to surrounding normal tissue. High intensity focused ultrasound (HIFU) is such a potential treatment, which can induce complete coagulation necrosis of a targeted tumor, at depth, through the intact skin. The concept of using HIFU as a non-invasive therapy has attracted attention in medicine for 60 years. Recently, it has received increasing interest as a promising modality for the treatment of localized solid malignancies. The goal of this article is to introduce recent clinical developments in the use of extracorporeal HIFU ablation for solid tumors, including those of liver, breast, bone, kidney, pancreas, soft tissue, and uterus. It describes the physical principles and ablative mechanisms, three-dimensional therapeutic regimes, and medical imaging used in HIFU. Currently, large numbers of patients with solid malignancy are already treated using HIFU, and short-term clinical results are very encouraging. However, large-scale randomized clinical trials are necessary to evaluate long-term efficacy of HIFU treatment for solid malignancies. It is concluded that this non-invasive ablation can be considered as a conventional therapy for widespread clinical use only when the results from prospective, randomized clinical trials worldwide are available.

Ultrasonic drug delivery--a general review

Ultrasound has an ever-increasing role in the delivery of therapeutic agents, including genetic material, protein and chemotherapeutic agents. Cavitating gas bodies, such as microbubbles, are the mediators through which the energy of relatively non-interactive pressure waves is concentrated to produce forces that permeabilise cell membranes and disrupt the vesicles that carry drugs. Thus, the presence of microbubbles enormously enhances ultrasonic delivery of genetic material, proteins and smaller chemical agents. Numerous reports show that the most efficient delivery of genetic material occurs in the presence of cavitating microbubbles. Attaching the DNA directly to the microbubbles, or to gas-containing liposomes, enhances gene uptake even further. Ultrasonic-enhanced gene delivery has been studied in various tissues, including cardiac, vascular, skeletal muscle, tumour and even fetal tissue. Ultrasonic-assisted delivery of proteins has found most application in transdermal transport of insulin. Cavitation events reversibly disrupt the structure of the stratus corneum to allow transport of these large molecules. Other hormones and small proteins could also be delivered transdermally. Small chemotherapeutic molecules are delivered in research settings from micelles and liposomes exposed to ultrasound. Cavitation appears to play two roles: it disrupts the structure of the carrier vesicle and releases the drug; and makes cell membranes and capillaries more permeable to drugs. There remains a need to better understand the physics of cavitation of microbubbles and the impact that such cavitation has on cells and drug-carrying vesicles.