High-intensity focused ultrasound in the treatment of benign prostatic hyperplasia

High-intensity focused ultrasound for noninvasive fetal therapy

High-intensity focused ultrasound (HIFU) consists of an ultrasonic beam that is focused within the body to induce tissue necrosis through both heat energy and as a result of cavitation, which occurs without damaging any intervening tissues. Therefore, it is possible to cauterize and treat tumors without surgical invasion by administering HIFU irradiation from outside the body. This approach has been clinically applied in various fields in recent years, and fetal therapy is no exception, with several clinical applications reported, mainly in basic experiments. This review summarizes the recent basic and clinical findings focusing on fetal treatment with HIFU.

High-intensity focused ultrasound for the treatment of prostate cancer: assessing location of failure after focal therapy in prostate cancer and review of histological characteristics and clinicopathologic correlates after treatment-a 5-year experience

High-intensity focused ultrasound (HIFU) is a noninvasive treatment option used for localized prostate cancer or salvage surgery after failed radiation therapy. Histological changes in post-treatment needle biopsies are reviewed to better understand HIFU failures. Between 2016 and 2021, 50 patients with localized prostate cancer were enrolled and treated in this study. Of these, 10 patients underwent salvage therapy after radiation failure and 7 did not have post-treatment needle biopsies available for review and were excluded. Inclusion criteria included pathologically confirmed prostate cancer and clinical stage T1/T2 disease. We describe the histological changes in post-treatment needle biopsies as part of routine follow-up. Biopsies were examined for presence, distribution and extent of residual adenocarcinoma, Gleason score, and ablative tissue changes. A total of 33 patients underwent HIFU hemi-ablation treatment of localized prostate cancer as primary treatment with post-treatment biopsies available for review. The average mean age of the patients was 64 years (range, 52-81 years). The average PSA (prostate-specific antigen) level of the patients was 6.3 ng/mL (range, 2.4-14.7 ng/mL). The Gleason scores assigned in pretreatment prostate needle biopsies are as follows: 3 + 3 (1 case, 3%), 3 + 4 (21 cases, 64%), 4 + 3 (9 cases, 27%), and 4 + 4 (2 cases, 6%). In post-treatment needle biopsies, 33 cases (100%) showed variable degrees of fibrosis ranging from mild to moderate. Twenty-four of 33 cases (73%) showed necrosis usually associated with acute and/or chronic inflammation. Histological examination of benign glands revealed glandular heterogeneity including atrophy and basal cell hyperplasia. Eight cases (24%) had residual prostatic adenocarcinoma after treatment, of which 4 cases were assigned Gleason score: ≥3 + 4. In cases with residual adenocarcinoma, 8 cases (100%) showed nuclear enlargement, 5 cases (63%), cytoplasmic vacuolization, and 1 case (13%) showed nuclear pyknosis; otherwise, no discernible effects of treatment were seen. Morphological alterations included a spectrum of changes ranging from extensive coagulative stromal necrosis secondary to thermal injury to atrophic changes in benign prostatic tissue after HIFU treatment. Our findings also support the hypothesis that HIFU failure results from inadequate targeting rather than failure within a treated zone.

Applications of High-Intensity Focused Ultrasound in the Treatment of Different Pathologies

Objective:

The purpose of this literature search was to review the benefits of high-intensity focused ultrasound (HIFU) and its application for different pathologies.

Methods:

This review summarizes the implementation of HIFU for different pathologic conditions. An National Center for Biotechnology Information, PubMed, MEDLINE, Medscape, and Google Scholar database search (1992–2016) was done with the following keywords: high-intensity focused ultrasound; uses of HIFU; and applications of HIFU in the liver, bones, uterine fibroids, prostate, breast, thyroid, pancreas, kidneys, brain, urinary bladder, and so on. Tables and graphs were created for all the variables included in the study, and descriptive statistics were applied.

Results:

In total, 110 records were identified, through database search. In addition, 20 articles were identified through other sources. Screening of the articles was performed, and 20 were removed due to duplication; further screening was performed for 110 articles, and 30 records were further excluded. Full-text articles were assessed for eligibility and 30 were retained. Full-text articles were excluded (N = 36) on the basis that research was performed on animals, and this review article was performed solely for human application. There were 42 qualitative syntheses that researches added to the review. In addition, 42 quantitative synthesis (meta-analysis) were added to the review.

Conclusion:

The conclusion of this narrative review indicates that HIFU is noninvasive, nonharmful, and effective in treating diseases and tumors of the brain, breast, bone, hepatic, renal, pancreas, and prostate; uterine fibroids; and many other solid tumors. Recent technological development suggests that HIFU is likely to play a significant role in future surgical practices. Further research works should be conducted on a large sample size to obtain more accurate results in the application of HIFU.

Arterial blood flow occlusion by high intensity focused ultrasound and histologic evaluation of its effect on arteries and surrounding tissues

High intensity focused ultrasound (HIFU) has been used in a number of clinical studies. High intensity focused ultrasound could become the minimally invasive tumor therapy of choice if it could be used to occlude the feeding arteries of tumors by exposure from outside the body. We used high intensity focused ultrasound to insonate the femoral arteries of both thighs of 18 male and female Sprague-Dawley (SD) rats, at frequencies of 1 or 3 MHz. Duration of exposure to high intensity focused ultrasound was 5 or 10 seconds. The femoral artery that was exposed to high intensity focused ultrasound was resected immediately after or 24 hours, 48 hours, or 12 days (at 1 MHz) after insonation. Arterial blood flow occlusion was achieved at 3 MHz, but not at 1 MHz. Free-field spatial peak intensity was 800 W/cm(2) at 1 MHz and 10 kW/cm(2) at 3 MHz. Histologic examination of the resected specimen showed that changes varied with ultrasound frequency and time course after exposure to high intensity focused ultrasound. We suggest that high intensity focused ultrasound might prove useful in occluding arteries when treating tumors in the clinical setting.

MR-acoustic radiation force imaging (MR-ARFI) and susceptibility weighted imaging (SWI) to visualize calcifications in ex vivo swine brain

PURPOSE

To present the use of MR-acoustic radiation force imaging (MR-ARFI) and susceptibility weighted imaging (SWI) to visualize calcifications in ex vivo brain tissue as a planning indicator for MR-guided focused ultrasound (MRgFUS).

MATERIALS AND METHODS

Calcifications were implanted in ex vivo swine brain and imaged using SWI, MR-ARFI, and computed tomography (CT). SWI-filtered phase images used 3D gradient recalled echo (GRE) images with a Fourier-based unwrapping algorithm. The MR-ARFI pulse sequence used a 2DFT spin-echo with repeated bipolar encoding gradients in the direction of the longitudinal ultrasound beam. MR-ARFI interrogations scanned a subregion (14 × 10 × 12 mm) of the brain surrounding the calcification. They were combined into a single displacement weighted map, using the sum of squares method. Calcification size estimates were based on image profiles plotted along the ±x and ±z direction, at the full-width half-maximum.

RESULTS

Both MR-ARFI and SWI were able to visualize the calcifications. The contrast ratio was 150 for CT, 12 for SWI, and 12 for MR-ARFI. Profile measures were 1.35 × 1.28 mm on CT, 1.24 × 1.73 mm on SWI, and 2.45 × 3.02 mm on MR-ARFI. MR-ARFI displacement showed a linear increase with acoustic power (20-80 W), and also increased with calcification size.

CONCLUSION

The use of SWI-filtered phase and MR-ARFI have the potential to provide a clinical indicator of calcification relevance in the planning of a transcranial MRgFUS treatment.

Multi-parameter acoustic imaging of uniform objects in inhomogeneous soft tissue

The problem studied in this paper is ultrasound image reconstruction from frequency-domain measurements of the scattered field from an object with contrast in attenuation and sound speed. The case in which the object has uniform but unknown contrast in these properties relative to the background is considered. Background clutter is taken into account in a physically realistic manner by considering an exact scattering model for randomly located small scatterers that vary in sound speed. The resulting statistical characteristics of the interference are incorporated into the imaging solution, which includes application of a total-variation minimization-based approach in which the relative effect of perturbation in sound speed to attenuation is included as a parameter. Convex optimization methods provide the basis for the reconstruction algorithm. Numerical data for inversion examples are generated by solving the discretized Lippman-Schwinger equation for the object and speckle-forming scatterers in the background. A statistical model based on the Born approximation is used for reconstruction of the object profile. Results are presented for a two-dimensional problem in terms of classification performance and compared with minimum-l2-norm reconstruction. Classification using the proposed method is shown to be robust down to a signal-to-clutter ratio of less than 1 dB.

Histopathological findings after treatment of prostate cancer using high-intensity focused ultrasound (HIFU)

BACKGROUND

High-intensity focused ultrasound (HIFU) treatment is a novel minimally invasive therapeutic option for patients with localized prostate cancer. Little is known about the histological findings in prostate biopsies upon HIFU treatment.

METHOD

We examined the spectrum of histological changes in prostate biopsies of 25 prostate cancer patients who were previously treated with HIFU. The biopsies were taken 180 days after HIFU treatment.

RESULTS

Seventy-two percent of the cases showed necrosis, often accompanied by acute, chronic, or granulomatous inflammation. Mild or moderate fibrosis was present in all biopsies. In benign glands, histological examination revealed a heterogeneous cellular damage and cellular response including cytologic atypia and basal cell hyperplasia. Eleven patients (44%) had residual prostatic carcinoma after treatment. In cases with residual adenocarcinoma, the majority of the cases (9/11, 88%) do no have apparent treatment effects. Two cases showed nuclear pyknosis. In summary, we report the histological findings in benign and malignant prostatic tissues after HIFU treatment. These findings include a spectrum of morphological changes ranging from apparent necrosis to more subtle cellular damage can be observed in benign prostatic tissue after HIFU treatment. There were minimal morphologic changes in residual adenocarcinoma after HIFU treatments.

CONCLUSION

The pathologist should be aware of common histologic findings in prostatic biopsies after HIFU treatment. We recommend routine reporting of Gleason scores in post-HIFU needle biopsies.

Shape-based ultrasound tomography using a Born model with application to high intensity focused ultrasound therapy

A shaped-based ultrasound tomography method is proposed to reconstruct ellipsoidal objects using a linearized scattering model. The method is motivated by the desire to detect the presence of lesions created by high intensity focused ultrasound (HIFU) in applications of cancer therapy. The computational size and limited view nature of the relevant three-dimensional inverse problem renders impractical the use of traditional pixel-based reconstruction methods. However, by employing a shape-based parametrization it is only necessary to estimate a small number of unknowns describing the geometry of the lesion, in this paper assumed to be ellipsoidal. The details of the shape-based nonlinear inversion method are provided. Results obtained from a commercial ultrasound scanner and a tissue phantom containing a HIFU-like lesion demonstrate the feasibility of the approach where a 20 mm x 5 mm x 6 mm ellipsoidal inclusion was detected with an accuracy of around 5%.

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.

Application of high-intensity focused ultrasound for umbilical artery occlusion in a rabbit model

OBJECTIVES

To investigate the application of high-intensity focused ultrasound (HIFU) for fetal umbilical artery blood flow occlusion in a rabbit model.

METHODS

A prototype HIFU transducer in combination with an imaging probe with Doppler capability was constructed. Using this transducer, HIFU was applied at 1.4, 2.75 or 5.5 kW/cm(2) through the maternal abdominal skin to the fetal intra-abdominal umbilical arteries of four time-mated Japanese White rabbits (11 fetuses) on gestational day 25. Courses of 5-s HIFU exposure were performed until cessation of umbilical blood flow and cardiac arrest were confirmed by Doppler ultrasonography. Fetal necropsy was performed and exposed lesions were assessed by microscopic histological analysis.

RESULTS

The mean diameter of the fetal umbilical artery was 0.6 +/- 0.2 mm and the mean peak systolic velocity of arterial blood flow was 44.7 +/- 18.5 cm/s. When HIFU was applied at 5.5 kW/cm(2), blood flow was completely occluded within 15 courses. HIFU exposure brought about vacuolar degeneration and destruction of elastic fibers in the tunica media of the artery.

CONCLUSIONS

HIFU can be used to occlude umbilical artery blood flow in fetal rabbits.

Blood flow occlusion via ultrasound image-guided high-intensity focused ultrasound and its effect on tissue perfusion

This study investigated the induction of tissue necrosis by arterial blood flow occlusion using ultrasound image-guided high-intensity focused ultrasound (HIFU). We constructed a prototype HIFU transducer in combination with an imaging probe that provided color Doppler imaging and ultrasound contrast imaging. The HIFU beam was aimed into a branch of the renal artery in vivo. The renal artery branches of eight rabbits were occluded by HIFU at an intensity of 4 kW/cm(2) (from 2 to 10 times of each sonication for 5 s). When the HIFU exposure was successful, complete cessation of blood flow was observed by color Doppler imaging with success rate of 100% (8/8). Furthermore, lack of perfusion was observed in the renal cortex with a contrast-enhanced image. Postmortem histologic evaluation showed a wedge-shaped area of infarction in six of seven cases, corresponding to the lack of the contrast medium in the ultrasound image. These results demonstrated that ultrasound image-guided HIFU can be used to induce arterial occlusion, thus producing infarction and necrosis of the perfused tissue.

Magnetic Resonance–Guided Focused Ultrasound Surgery for the Noninvasive Curative Ablation of Tumors and Palliative Treatments: A Review

This article reviews and discusses the up-to-date data on and feasibility of focused ultrasound surgery. This technique uses high-energy ultrasound beams that can be directed to penetrate through the skin and various soft tissues, focus on the target, and destroy tumors by increasing the temperature at the targeted tissue volume. The boundaries of the treatment area are sharply demarcated (focused) without causing damage to the surrounding organs. Although the idea of using sound waves to ablate tumors was first demonstrated in the 1940 s, only recent developments have enabled this technology to become more controlled and, hence, more feasible. The major breakthrough toward its clinical use came with coupling the thermal ablative process to advanced imaging. The development of magnetic resonance as the foundation to guide and evaluate the end results of focused ultrasound surgery treatment, the image guidance of the ultrasound beam, and the development of a reliable method for tissue temperature measurement and real-time feedback of the extent of tissue destruction have pushed this novel technology forward in oncological practice.

High-intensity focused ultrasound principles, current uses, and potential for the future

High-intensity focused ultrasound (HIFU) continues to be a very attractive option for minimally invasive procedures. Using well-established principles, this ablative therapy can be used to treat a number of benign and malignant diseases with few side effects. During the last 15 years, there has been an enormous amount of work, both laboratory based and in the form of clinical trials, aimed at developing devices that can deliver treatments with safe and effective outcomes. In this article, we aim to outline the principles of HIFU, describe the current commercially available machines and their applications, and discuss the role of HIFU in the future.

Feasibility of US-guided high-intensity focused ultrasound treatment in patients with advanced pancreatic cancer: initial experience

The study was approved by the university ethics committee, and informed consent was obtained from all patients. The purpose of this study was to prospectively evaluate ultrasonographically guided high-intensity focused ultrasound in the treatment of patients with advanced-stage pancreatic cancer. Eight patients underwent high-intensity focused ultrasound ablation, and laboratory and radiologic examinations were performed after intervention. Changes in symptoms and survival time were noted at follow-up. No complications were observed, and preexisting severe back pain disappeared after intervention. Follow-up images revealed an absence of tumor blood supply and shrinkage of the ablated tumor. Four patients died, and four patients were alive at the time of this writing, with a median survival time of 11.25 months. The authors conclude that high-intensity focused ultrasound ablation is safe and feasible in the treatment of advanced pancreatic cancer.

High-intensity focused ultrasound in the treatment of postpartum hemorrhage: an animal model

OBJECTIVE

To investigate the use of high-intensity focused ultrasound (HIFUS) to reduce uterine artery blood flow in ewes in the postpartum period.

METHODS

HIFUS was applied to the uterine arteries of seven ewes in the postpartum period. Arterial flow velocities were measured before and after the procedure at the site of HIFUS application (target), as well as 3 cm upstream and 3 cm downstream from the target. The uterine arteries were then removed for macroscopic and histological examination.

RESULTS

Maximum flow velocities in the target area increased after the procedure by 350% and those upstream from the target decreased by 65%. Macroscopically, the vessel diameter was shown to have reduced at the site of HIFUS application. Microscopically, both the endothelium and media showed thermal lesions. Tissues surrounding the arteries were macroscopically and microscopically normal.

CONCLUSION

Exposure of uterine arteries to HIFUS reduces the vessel diameter and thus induces a dramatic increase in the maximum flow velocities within the target area. HIFUS may have a role in the treatment of postpartum hemorrhage.

Preliminary experience using high intensity focused ultrasound for the treatment of patients with advanced stage renal malignancy

PURPOSE

We present the preliminary results of patients with advanced stage renal malignancy treated with high intensity focused ultrasound (HIFU), and investigate the safety and feasibility of using HIFU in the treatment of selected patients with renal tumors.

MATERIALS AND METHODS

HIFU treatment was performed in 12 patients with advanced stage renal cell carcinoma and 1 patient with colon cancer metastasized to kidney. Patients were followed after treatment to observe complications and long-term therapeutic efficacy. Complications and changes in symptoms seen at presentation were recorded. Mid stream urine specimens were sent for microscopy and serum creatinine was measured postoperatively. Followup radiological examinations were performed to detect tumor response to the ablation.

RESULTS

A total of 13 patients received HIFU treatment safely, including 10 who had partial ablation and 3 who had complete tumor ablation. After HIFU hematuria disappeared in 7 of 8 patients and flank pain of presumed malignant origin disappeared in 9 of 10 patients. Postoperative images showed decrease in or absence of tumor blood supply in the treated region and significant shrinkage of the ablated tumor. Of the 13 patients 7 died (median survival 14.1 months, range 2 to 27) and 6 were still alive with median followup of 18.5 months (range 10 to 27).

CONCLUSIONS

This preliminary experience suggests that HIFU could be safe and feasible in the treatment of patients with advanced renal malignancy.

High intensity focused ultrasound: surgery of the future?

For 50 years, high intensity focused ultrasound (HIFU) has been a subject of interest for medical research. HIFU causes selective tissue necrosis in a very well defined volume, at a variable distance from the transducer, through heating or cavitation. Over the past decade, the use of HIFU has been investigated in many clinical settings. This literature review aims to summarize recent advances made in the field. A Medline-based literature search (1965-2002) was conducted using the keywords "HIFU" and "high intensity focused ultrasound". Additional literature was obtained from original papers and published meeting abstracts. The most abundant clinical trial data comes from studies investigating its use in the treatment of prostatic disease, although early research looked at applications in neurosurgery. More recently horizons have been broadened, and the potential of HIFU as a non-invasive surgical tool has been demonstrated in many settings including the treatment of tumours of the liver, kidney, breast, bone, uterus and pancreas, as well as conduction defects in the heart, for surgical haemostasis, and the relief of chronic pain of malignant origin. Further clinical evaluation will follow, but recent technological development suggests that HIFU is likely to play a significant role in future surgical practice.

Functional and histological changes in rat femoral arteries by HIFU exposure

This study was an investigation of arterial contractility in response to high-intensity focused ultrasound (HIFU) and of histologic changes to the artery with various intensities of HIFU. We constructed a prototype HIFU transducer in combination with an imaging probe that provides color Doppler imaging and Doppler velocimetry. HIFU was applied through the skin to deep femoral arteries in left thighs of Sprague-Dawley rats; color images of the blood flow were used to aim the HIFU beam. Peak intensities used were 530, 1080, 2750 and 4300 W/cm2. The duration of each HIFU exposure was 5 s. HIFU was applied to five focal spots of each leg. These focal spots were aligned with a spacing of 1.0 mm so as to form a line across the artery. Blood flow occlusion was accomplished by HIFU at an intensity of 4300 W/cm2, but the flow continued with the lower intensities. Peak systolic velocities (PSVs) of blood flow as measured by Doppler velocimetry increased in the arteries to which HIFU had been applied at 1080 and 2750 W/cm2. The increase corresponded with HIFU intensity. Exposure to HIFU at 530 W/cm2 did not change the blood flow velocity. Histologic studies have demonstrated that exposure to HIFU at 2750 and 4300 W/cm2 leads to vacuolar degeneration and destruction of elastic fibers of the tunica media of the artery. Exposure at 1080 W/cm2 led to increased PSV, but did not induce histologic changes in the vessel wall. In conclusion, the response of the artery to HIFU varied with intensity. Vascular contraction without tissue degeneration occurred at low intensity; with increasing intensity, the tissue degeneration detectable in histology reduced the vascular diameter and, finally, at high intensity, the blood flow was occluded. Although these phenomena appeared to be mainly due to thermal effects, mechanical effects might have some role, particularly on vascular contraction.

Treatment of uterine fibroid tumors in an in situ rat model using high-intensity focused ultrasound

OBJECTIVE

To determine the efficacy and safety of high-intensity focused ultrasound (HIFU) for the treatment of uterine fibroid tumors in an in situ animal model.

DESIGN

High-intensity focused ultrasound was applied intraoperatively to uterine fibroid tumors in rats.

SETTING

Department of Bioengineering, and Applied Physics Laboratory, University of Washington, Seattle, Washington.

ANIMAL(S)

Thirty-five tumors in 27 Eker rats that had spontaneous in situ uterine fibroids were randomly assigned into two groups receiving HIFU (n = 29) or sham (n = 6) treatments.

INTERVENTION(S)

Animals were anesthetized, and tumors were exposed surgically. The HIFU was applied at 3.5 MHz in 10-second bursts to produce coagulative necrosis lesions (3 mm by 10 mm), spaced 5 mm apart. Sham treatments consisted of exposing the tumors, and handling them similarly to those in the HIFU treatment group, but HIFU was not applied.

MAIN OUTCOME MEASURE(S)

Tumor volume was measured every week transabdominally using B-mode ultrasound imaging. Gross examination and histological analysis were performed after euthanasia.

RESULT(S)

More than half of the tumors in the HIFU treatment group showed significant tumor volume reduction. The average tumor volume in the sham treatment group increased 40-fold. Gross and histological analysis showed coagulative necrosis of tumor cells in the HIFU treatment group.

CONCLUSION(S)

The HIFU may provide an effective and safe method of treating uterine fibroid tumors.

Benign prostatic hyperplasia

In both ageing men and women, there is an increasing incidence of lower urinary tract symptoms (LUTS) which are increasing. These infections have many possible causes, including smooth muscle dysfunction, neurological factors and benign prostatic hyperplasia. Up to 15% to 25% of men aged 50-65 years have LUTS of sufficient severity to interfere with their quality of life. Although benign prostatic hyperplasia is an important cause of these symptoms, and can have serious consequences, clinicians should be aware of these other causes so that the appropriate diagnosis is made before invasive treatments are started. New medical treatments, including alpha-adrenergic blocking agents and 5 alpha-reductase inhibitors mean that many men without complications such as infection, bleeding, or chronic retention, and with mild to moderate symptoms, should be managed in primary care. Combined local protocols between primary and secondary care will help to establish which men with persistent symptoms or complications need referral for a urological opinion to determine the need for further investigation and more invasive forms of management. We review the pathophysiology of the disease, and current approaches to investigation and management of this common problem.

Treatment of uterine leiomyosarcoma in a xenograft nude mouse model using high-intensity focused ultrasound: a potential treatment modality for recurrent pelvic disease

OBJECTIVE

The objective was to test the efficacy of high-intensity focused ultrasound (HIFU) for treatment of uterine leiomyosarcoma in a Xenograft nude mouse model.

METHODS

A total of 65 athymic nude mice were inoculated subcutaneously with 5 to 7 x 10(6) ELT-5B cells, a uterine leiomyosarcoma cell line derived from the Eker rat. Thirty animals showed tumor growth. The tumor volume was measured transcutaneously once a week. Animals were randomly assigned to three groups: HIFU treatment (n = 17), sham treatment (n = 7), and control (n = 6). A HIFU device, operating at a frequency of 2.0 MHz and an intensity of 2000 W/cm(2), was used for treatment.

RESULTS

Within 3 weeks of a single HIFU treatment, 100% reduction in tumor volume was observed in all animals, except one. A second HIFU treatment was applied to that animal, resulting in 100% reduction in tumor volume. The tumors in the sham-treated animals continued to grow at a similar rate to that of the control group to approximately 500% of the tumor volume at the time of treatment. All animals were monitored for a maximum of 3 months. No metastasis was observed in the HIFU-treated animals. Histological examination confirmed a complete tumor disappearance after HIFU treatment.

CONCLUSION

We have shown that HIFU can effectively treat uterine leiomyosarcoma tumors inoculated in Xenograft nude mice, demonstrating HIFU's potential use for treatment of recurrent uterine leiomyosarcoma.

Therapeutic ultrasound: its application in drug delivery

Ultrasound is best known for its imaging capability in diagnostic medicine. However, there have been considerable efforts recently to develop therapeutic uses for it. The purpose of this review is to summarize some of the recent advances made in the area of therapeutic ultrasound as they relate to drug delivery. In particular, this review will focus on the applications of ultrasound to enhance the delivery and effect of three distinctive therapeutic drug classes: chemotherapeutic, thrombolytic, and gene-based drugs. In addition, ultrasound contrast agents have been recently developed for diagnostic ultrasound. New experimental evidence suggests that these contrast agents can be used as exogenous cavitation nuclei for enhancement of drug and gene delivery. Thus, brief review of this new class of agents and their roles in drug delivery will also be provided. By comparison to diagnostic ultrasound, progress in therapeutic use of ultrasound has been somewhat limited. The recent successes in ultrasound-related drug delivery research positions ultrasound as therapeutic tool for drug delivery in the future.

Pathological changes in human malignant carcinoma treated with high-intensity focused ultrasound

The purpose of this study was to investigate the pathologic changes of extracorporeal ablation of human malignant tumors with high-intensity focused ultrasound (HIFU). HIFU treatment was performed in the 164 patients with liver cancer, breast cancer, malignant bone tumor, soft tissue sarcoma and other malignant tumors at focal peak intensities from 5000 W x cm(-2) to 20,000 W x cm(-2), with operating frequencies of 0.8 to 3.2 MHz. To explore the pathologic impact of extracorporeal HIFU, 30 patients with malignant carcinoma underwent surgical removal after HIFU treatment. Pathologic findings showed that the treated tissues demonstrated homogeneous coagulative necrosis with an irreversible tumor cell death and severe damage to tumor blood vessels at the level of microsvasculature within the HIFU-targeted region. Thermolesions to intervening tissue were never observed. The treated region had a sharp border comprising only several cell layers between the treated and untreated areas. The repair of lesions had the processes of necrotic tissue absorption and granulation tissue replacement. It is concluded that extracorporeal treatment of human solid malignancies with HIFU could be safe, effective and feasible. As a noninvasive therapy, HIFU would be used clinically to treat patients with solid malignancies.

Sexual function in patients with benign prostatic hyperplasia

Sexual health has significant impact on quality of life among men with benign prostatic hyperplasia (BPH). The degree of sexual dysfunction matches the severity of lower urinary tract symptoms (LUTS). Treatment of BPH affects not only LUTS, but sexual function as well. Medical, surgical, and minimally invasive therapies differ in their effect on erectile function, ejaculation, and sexual satisfaction. Choice of treatment modality takes into account baseline sexual function and patient expectations. This review outlines the relationship between LUTS and sexual function and how they change with the currently available treatments.

Histopathological changes associated with high intensity focused ultrasound (HIFU) treatment for localised adenocarcinoma of the prostate

AIMS

Investigation of the histopathological changes in prostatectomy specimens of patients with prostate cancer after high intensity focused ultrasound (HIFU) and identification of immunohistochemical markers for tissue damage after HIFU treatment.

METHODS

Nine patients diagnosed with adenocarcinoma of the prostate underwent unilateral HIFU treatment seven to 12 days before radical prostatectomy. The prostatectomy specimens were analysed histologically. Immunohistochemical staining and electron microscopy were performed to characterise more subtle phenotypic changes.

RESULTS

All prostatectomy specimens revealed well circumscribed HIFU lesions at the dorsal side of the prostate lobe treated. Most epithelial glands in the centre of the HIFU lesions revealed signs of necrosis. Glands without apparently necrotic features were also situated in the HIFU lesions, raising the question of whether lethal destruction had occurred. This epithelium reacted with antibodies to pancytokeratin, prostate specific antigen (PSA), and Ki67, but did not express cytokeratin 8, which is indicative of severe cellular damage. Ultrastructural examination revealed disintegration of cellular membranes and cytoplasmic organelles consistent with cell necrosis. HIFU treatment was incomplete at the ventral, lateral, and dorsal sides of the prostate lobe treated.

CONCLUSIONS

HIFU treatment induces a spectrum of morphological changes ranging from apparent light microscopic necrosis to more subtle ultrastructural cell damage. All HIFU lesions are marked by loss of cytokeratin 8. HIFU does not affect the whole area treated, leaving vital tissue at the ventral, lateral, and dorsal sides of the prostate.

Clinical features and management of benign prostatic hyperplasia

Benign prostatic hyperplasia represents the most common benign neoplastic condition afflicting men and has a major impact on the health of the population. It refers to a regional and nodular growth of stromal proliferation which, because of its proximity to the urethra, causes varying degrees of bladder outflow obstruction.

In vivo demonstration of noninvasive thermal surgery of the liver and kidney using an ultrasonic phased array

A 256-element, continuous-wave ultrasonic phased array has been used to thermally coagulate deep-seated liver and kidney tissue. The array elements were formed on a 1-3 piezocomposite bowl with a 10-cm radius of curvature and 12-cm diameter. The 0.65 x 0.65 cm2 projection elements were driven at 1.1 MHz by a custom-built amplifier system. A series of in vivo porcine experiments demonstrated the ability to coagulate liver and kidney tissue using the large-scale phased array. The temperature response of the treatment was guided and monitored using magnetic resonance (MR) images. Focal lesion volumes greater than 0.5 cm3 in kidney and 2 cm3 in liver were formed from a single 20-s sonication.

Preliminary results of a phase I dose escalation clinical trial using focused ultrasound in the treatment of localised tumours

OBJECTIVE

The primary aim of this phase I trial was to assess the tolerance of cancer patients to focused ultrasound (FUS) treatment in a variety of different sites and to document any associated acute or delayed toxicity. This would appear to be the first time that treatment has been given without sedation or anaesthesia.

METHODS

Patients with advanced and/or metastatic disease were eligible for entry into this study. Previous work has established that an in situ ablative intensity (AI) of 1500 W/cm2 Isp for 1 s achieves coagulative necrosis at the focal spot. Ultrasonic exposures of 25-100% of AI for 1 s were delivered to preselected tissue volumes. Pain questionnaires recording any side effects were completed by the patient and the investigator separately. Ultrasound images of the target volume were taken before, immediately after, and 1 week after treatment.

RESULTS

A total of 14 patients have been entered into this study to date. Seven patients were treated at their primary site and seven received treatment to one of their metastases. No treatment needed to be stopped because of pain. Eight of the 14 patients did not complain of any side effect during or after the treatment. One patient complained of mild, and two of moderate pain during the week following treatment. One patient developed an asymptomatic blister on the skin.

CONCLUSION

Focused ultrasound is a safe, well-tolerated and non-invasive method of delivering ablative thermal energy to selected tumours. More clinical trials are needed to assess the role of this modality in the treatment of cancer.

High intensity focused ultrasound in benign prostatic hyperplasia

Benign prostatic hyperplasia (BPH) is an extremely common condition and represents a major health issue in terms of patient numbers and treatment cost. Traditionally, the choice of treatment has been between watchful waiting and surgery, however, the side effects of surgery lead to reluctance for treatment in many men, other than those with severe symptoms and complications. In the last 2 decades there has been a rapid expansion in the number of treatments being offered and the number of patients submitting to novel therapies. Medical management has evolved to achieve a central role in the management of BPH. Heat based treatments are also being investigated with considerable interest. Transrectal high intensity focused ultrasound (HIFU) is one such treatment, which allows radiation-free treatment, without the need for intra-urethral manipulation. Imaging can be performed during treatment and treatment results in symptomatic improvement, which is retained with medium-term follow-up. It involves a brief hospital stay and post-operative complications are few. The use of HIFU has also been extended to the treatment of renal, prostatic and bladder tumours and the results in these areas suggest further expansion of its role in urological practice.

A 256-element ultrasonic phased array system for the treatment of large volumes of deep seated tissue

A 256-element phased array has been designed, constructed, and tested for ablative treatment of large focal volumes of deep seated tissue. The array was constructed from a 1.1-MHz, 1-3 composite piezoelectric spherical shell with a 10-cm radius of curvature and a 12-cm diameter. The array was tested to determine its electroacoustic efficiency and inter-element coupling under high acoustic power conditions. A series of in vivo porcine experiments demonstrated the ability to produce deep seated tissue lesions in thigh muscle using the large scale phased array. The array was used to heat and coagulate tissue volumes >5 cm(3) in a single ultrasound exposure using multiple foci and temporally scanned power deposition patterns. The spatial and temporal experimental results for large, heated focal volumes correlated very well with the simulated temperature response model for homogeneous tissue. A 25-cm(3) tissue volume was coagulated in a 90-min period using overlapping large ultrasound exposures.

The long-term effects of prostatic infarction in the rat

OBJECTIVE

To evaluate the long-term effects of infarction, which usually induces organ atrophy, on the prostate by examining the changes occurring in rat ventral prostate after infarction.

MATERIALS AND METHODS

The unilateral arteriolar branches to the ventral prostate were electrocauterized under an operative microscope in 10 adult rats. The gross and histological changes of the treated lobes of the ventral prostate were compared with those of untreated control lobes in the same rats 12 weeks later.

RESULTS

The size and mean (SD) weight of the treated lobes decreased markedly, to 148 (34) mg, compared with those of the controls, at 698 (62) mg (P<0.01). The treated lobes were composed of both normal and atrophic glandular tissue.

CONCLUSION

Prostatic atrophy can be induced by infarction in the rat; prostatic infarction might have potential as a new therapeutic strategy in the treatment of benign prostatic hyperplasia.

Clinical outcome of high-intensity focused ultrasound for treating benign prostatic hyperplasia: preliminary report

OBJECTIVES

To preliminarily summarize the clinical outcomes of the transrectal high-intensity focused ultrasound procedure using the prototype Sonablate (HIFU1) and the new Sonablate-200 (HIFU2) for treating symptomatic benign prostatic hyperplasia.

METHODS

We treated 35 and 22 patients with HIFU1 and HIFU2, respectively. Preoperative and postoperative evaluations were made using the International Prostate Symptom Score (IPSS), quality of life (QOL) data, and the results of uroflowmetry and transrectal ultrasound, and any complications were noted.

RESULTS

IPSS and QOL scores showed significant improvement after using both HIFU1 and HIFU2 at 3, 6, and 12 months, postoperatively (P < 0.0001 to < 0.01; Wilcoxon signed-ranks test). Maximum flow rate (8.9 to 15.5 mL/s, P < 0.001) and prostatic volume (32.2 to 22.8 mL, P < 0.01) were significantly improved at 12 months postoperatively in patients who underwent HIFU2 treatment but not in patients who underwent HIFU1. Two hematospermia and one gross hematuria in patients treated with HIFU1 and one epididymitis in a patient treated with HIFU2 were seen but no severe complications were noted.

CONCLUSIONS

Focused ultrasound is an effective new technology by which tissue can be destroyed at a site distant from the source of energy without damaging surrounding tissue. The clinical efficacy of HIFU2 was superior to that of the prototype HIFU1.

Recent developments in the surgical management of benign prostatic hyperplasia

A new era in the surgical management of benign prostatic hyperplasia (BPH) has emerged in the past decade. A variety of less invasive treatment modalities have been introduced and well-established surgical treatments are being reassessed. Although progress has been made in the management of BPH, the substantial economic burden to the healthcare system caused by BPH emphasizes the importance of cost-effective treatment. Open prostatectomy is the most efficient BPH treatment for relieving symptoms and improving uroflow, but it is also the most invasive and morbid. Transurethral resection of the prostate (TURP) is still the "gold standard" for treatment of BPH, but open prostatectomy has been reported to have a lower perioperative mortality than TURP, and low retreatment rates reduce the long-term cost. The morbidity associated with TURP, such as impotence or urinary incontinence, has been reduced in recent years while new features, such as performing TURP under local anesthesia and bipolar electrosurgical techniques, have been introduced. Transurethral electrovaporization of the prostate (TVP) is a recent modification of TURP that has rapidly gained popularity. TVP greatly reduces TURP syndrome, provides good hemostasis, and may reduce catheterization and hospitalization times. Transurethral incision of the prostate (TUIP) is another safe and inexpensive procedure that is well-documented and comparable to TURP in long-term efficacy. TUIP is an underused procedure with which the newer, less invasive treatments should be compared. Whereas the well-established surgical treatments primarily relieve obstruction by tissue ablation, some of the newer treatment modalities may ameliorate lower urinary tract symptoms (LUTS) with minimal urodynamic change. In some of the newer nonresection treatments, no major significant postoperative reduction in prostate volume can be demonstrated. Laser treatments are based on a broad variety of techniques, generators, and fibers, of which most have initially demonstrated promising results. Well-known techniques include visually laser-assisted prostatectomy (VLAP) and interstitial laser coagulation (ILC). The laser techniques are generally not as effective as TURP, but are safe under local anesthesia on an outpatient basis with low complication rates. Transurethral microwave thermotherapy of the prostate (TUMT) and radiofrequency transurethral needle ablation (TUNA) are minimally invasive, safe new therapies. There is some evidence that the procedures create long-term, alpha-adrenoceptor-like blockade. Complications, except for transient catheterization in up to 40% of patients, may be practically nonexistent. The cost is difficult to estimate and the long-term outcome is still to be assessed. If the newer, less invasive treatment modalities provide stable long-term results and competitive costs, they will be tempting alternatives to prostate resections and may also challenge medical therapy.

Minimally invasive therapies for the treatment of symptomatic benign prostatic hyperplasia: the University of Florida experience

OBJECTIVE

To describe the University of Florida experience with minimally invasive therapies in the surgical treatment of benign prostatic hyperplasia (BPH).

BACKGROUND DATA

Typically, the standard surgical treatment for symptomatic benign prostatic hyperplasia (BPH) has been transurethral resection of the prostate (TURP). Due to the morbidity associated with TURP, several minimally invasive therapies, such as laser, microwaves, high intensity focused ultrasound, and radiofrequency needle ablation, have been utilized to treat BPH.

METHODS

The authors review their experience, along with that of others, with various forms of heat therapy in the treatment of BPH.

RESULTS AND CONCLUSIONS

Although high intensity focused ultrasound (HIFU), interstitial laser, and microwaves procedures have been shown to be effective in the treatment of BPH, our experience has been with laser, VaporTrode, and TUNA. We found that VaporTrode and TUNA currently offer several advantages over many of the other modalities.

Minimally invasive treatment for benign prostatic hyperplasia

The armamentarium of minimally invasive treatment modalities for patients with benign prostatic hyperplasia has constantly increased during the past decade. The energy sources used range from micro-/radiofrequency waves to high-intensity focused ultrasound, laser vaporization/coagulation/resection and electrosurgical techniques. Each of these devices has its particular advantages and disadvantages. At present, the most intensively studied techniques are interstitial laser coagulation, holmium laser resection and new approaches to transurethral electrosurgery.