Time-dependent change of blood flow in the prostate treated with high-intensity focused ultrasound

Current status and future outlook of ultrasound treatment for prostate cancer

Radical prostatectomy and radiation therapy are the standard treatment options for localized prostate cancer (PC). However, radical prostatectomy may cause the deterioration of urinary and sexual function, and radiation-induced hemorrhagic cystitis and severe rectal bleeding are risk factors for fatal conditions in patients after radiation therapy. With the recent development of magnetic resonance imaging (MRI) for the localization of clinically significant PC (csPC) and treatment modalities, "focal therapy", which cures csPC while preserving anatomical structures related to urinary and sexual functions, has become a minimally invasive treatment for localized PC. Based on the clinical results of transrectal high-intensity focused ultrasound (HIFU) for localized PC in the whole gland and focal therapy, HIFU is considered an attractive treatment option for focal therapy. Recently, the short-term clinical results of transurethral high-intensity directional ultrasound (HIDU) have been reported. With the resolution of some issues, HIDU may be commonly used for PC treatment similar to HIFU. Because HIFU and HIDU have limitations regarding the treatment of patients with large prostate calcifications and large prostate volumes, the proper use of these modalities will enable the treatment of any target area in the prostate. To establish a standard treatment strategy for localized PC, pair-matched and historically controlled studies are required to verify the oncological and functional outcomes of ultrasound treatment for patients with localized PC.

Development and future prospective of treatment for localized prostate cancer with high-intensity focused ultrasound

High-intensity focused ultrasound (HIFU) was experimentally used for focal therapy for anti-cancer effects in prostate cancer (PC). Focal therapy is a diagnosis-based investigational treatment option for localized PC that cures clinically significant PC (csPC) while preserving the anatomical structures related to urinary and sexual function based on its spread observed using multi-parametric magnetic resonance imaging (mpMRI). The European Association of Urology indicated that the current status of focal therapy for localized PC was an investigational modality and encouraged prospective recording of outcomes and recruitment of suitable patients in 2018. During the last few years, large-population multi- and single-center prospective studies have investigated focal therapy as a treatment strategy for localized PC. In a multicenter prospective study with 5-year follow-up, failure-free survival, which was defined as avoidance of local salvage therapy (surgery or radiotherapy), systemic therapy, metastases, and prostate cancer-specific death, was 88%. In the previous studies, there was no significant influence on urinary function before and at 3 months after the treatment, although transient impairment was reported 1 month after the treatment. Pad- and leak-free continence was preserved in 80-100% of the patients after treatment. Erectile function was significantly impaired in the initial 3 months after treatment compared to the pretreatment values, but it improved 6 months after the focal therapy in the previous reports. Paired comparison studies and cohort studies with long-term follow-up will contribute to verifying this treatment's clinical outcomes for patients with localized PC.

High-Intensity Focused Ultrasound (HIFU) Focal Therapy for Localized Prostate Cancer with MRI-US Fusion Platform

Objective

The study aimed at investigating the outcome of prostate HIFU focal therapy using the MRI-US fusion platform for treatment localization and delivery.

Methods

It is a prospectively designed case series of HIFU focal therapy for localized prostate cancer. The inclusion criteria include clinical tumor stage ≤T2, visible index lesion on multiparametric MRI less than 20 mm in diameter, absence of Gleason 5 pattern on prostate biopsy, and PSA ≤ 20 ng/ml. HIFU focal therapy was performed in the conventional manner in the beginning 50% of the series, whereas the subsequent cases were performed with MRI-US fusion platform. The primary outcome was treatment failure rate which is defined by the need of salvage therapy. Secondary outcomes included tumor recurrence in follow-up biopsy, PSA change, perioperative complications, and postoperative functional outcomes.

Results

Twenty patients underwent HIFU focal ablation. HIFU on an MRI-US fusion platform had a trend of a longer total operative time than the conventional counterpart (124.2 min vs. 107.1 min, p=0.066). There was no difference in the mean ablation volume to lesion volume ratio between the two. The mean PSA percentage change from baseline to 6-month is more significant in the conventional group (63.3% vs. 44.6%, p=0.035). No suspicious lesion was seen at 6-month mpMRI in all 20 patients. Two patients, one from each group, eventually underwent radical treatment because of the presence of clinically significant prostate cancer in the form of out-of-field recurrences during follow-up biopsy. No significant difference was observed before and after HIFU concerning uroflowmetry, SF-12 score, and EPIC-26 score. It was observed that energy used per volume was positively correlated with PSA density of the patient (r = 0.6364, p=0.014).

Conclusion

In conclusion, HIFU with conventional or MRI-US fusion platform provided similar oncological and functional outcomes.

Analysis of oncological outcomes of whole-gland therapy with high-intensity focused ultrasound for localized prostate cancer in clinical and technical aspects: a retrospective consecutive case-series analysis with a median 5-year follow-up

PURPOSE

This study aimed to analyze technical and clinical factors related to oncological outcomes in patients with localized prostate cancer (PC) who were treated with whole-gland high-intensity focused ultrasound (HIFU).

MATERIALS AND METHODS

From 2007-2014, patients diagnosed with localized PC who underwent whole-gland HIFU were consecutively included retrospectively. Biochemical failure was defined according to the Phoenix ASTRO guidelines. The relationship between oncological outcomes and technical and clinical factors was evaluated.

RESULTS

The study cohort included 428 patients. The median age was 67 years, and the median prostate-specific antigen level was 7.61 ng/mL. Patient risk classifications were low (n = 102), intermediate (n = 240), and high (n = 86). Biochemical disease-free survival rates of patients with HIFU for localized PC in the total, low-, intermediate-, and high-risk groups according to D'Amico risk groups over a median follow-up period of 5 years (range 9-144) were 68.4%, 80.4%, 65.6%, and 61.6%, respectively. In multivariate logistic regression analyses to predict biochemical failure of the treatment, neoadjuvant hormonal therapy (NHT) in the high-risk group (OR 0.225, p = 0.015), and compression method in the low- (OR 0.178, p = 0.030), intermediate- (OR0.291, p < 0.0001), and high-risk (OR 0.316, p = 0.049) groups were significant factors that reduced the risk of biochemical failure after treatment. There were no significant differences in complications between patients treated with compression and those treated conventionally.

CONCLUSIONS

NHT may potentially improve oncological outcomes for patients in the high-risk group, and compression methods can improve the oncological outcomes of whole-gland therapy with HIFU.

Focal therapy with high-intensity focused ultrasound for the localized prostate cancer for Asian based on the localization with MRI-TRUS fusion image-guided transperineal biopsy and 12-cores transperineal systematic biopsy: prospective analysis of oncological and functional outcomes

BACKGROUND

We evaluated clinical outcomes of region target focal therapy with high-intensity focused ultrasound (HIFU) for the localized prostate cancer (PCa) based on magnetic resonance imaging-based biopsy and systematic prostate biopsy for Asian.

METHODS

We prospectively recruited patients with localized PCa, located their significant tumors using MRI-transrectal ultrasound (TRUS) elastic fusion image-guided transperineal prostate biopsy and 12-cores transperineal systematic biopsy, and focally treated these regions in which the tumors were located in the prostate using HIFU. Patients' functional and oncological outcomes were analyzed prospectively.

RESULTS

We treated 90 men (median age 70 years; median PSA level 7.26 ng/ml). Catheterization was performed within 24 h after the treatment in all patients. Biochemical disease-free rate was 92.2% during 21 months follow-up when use of Phoenix ASTRO definition. In follow-up biopsy, significant cancer was detected in 8.9% of the patients in un-treated areas. Urinary functions, including international prostate symptom score (IPSS) (P < 0.0001), IPSS quality of life (QOL) (P = 0.001), overactive bladder symptom score (OABSS) (P < 0.0001), EPIC urinary domain (P < 0.0001), maximum urinary flow rate (P < 0.0001), and IIEF-5 (P = 0.001), had significantly deteriorated at 1 month after treatment, but improved to preoperative levels at 3 or 6 months. Rates of erectile dysfunction and ejaculation who had the functions were 86% and 70%, respectively, at 12 months after treatment.

CONCLUSIONS

The present treatment for Asian would have similar oncological and functional outcomes to those in previous reports. Further large studies are required to verify oncological and functional outcomes from this treatment for patients with localized PCa.

[FOCAL THERAPY WITH HIGH-INTENSITY FOCUSED ULTRASOUND FOR THE LOCALIZED PROSTATE CANCER BASED ON THE LOCALIZATION WITH MRI-TRUS FUSION IMAGE-GUIDED BIOPSY: 1-YEAR PROSPECTIVE STUDY]

(Objective) To evaluate the efficacy and invasiveness of focal therapy with transrectal high-intensity focused ultrasound (HIFU) for localized prostate cancer based on spatial location of significant cancer with magnetic resonance imaging (MRI)-transrectal ultrasound (TRUS) fusion image-guided biopsy. (Methods) Patients with low- and intermediate-risk significant prostate cancer who were followed-up at least 1 year, were prospectively recruited. The spatial localization of the significant cancer was determined by MRI-TRUS fusion image-guided transperineal prostate biopsy. Focal therapy targeting the regions of significant cancer was performed by transrectal HIFU using a Sonablate^® 500 (SonaCare Medical, Indianapolis, IN, USA). Serum prostate-specific antigen (PSA) kinetics, multi-parametric MRI, and MRI-TRUS fusion image-guided prostate biopsy were analyzed to determine the treatment efficacy. Questionnaires and uroflowmetry were performed to evaluate the invasiveness. (Results) Ten men with median age of 67 years (range, 48-79), median PSA level of 7.07 ng/ml (range, 4.67-15.99), median prostate volume of 25 ml (range, 19-36) were treated. Median operative time was 29.5 minutes (range, 14-85). Catheterization was performed within 24 hours after the treatment in all patients. The median PSA concentration significantly decreased to 1.35 ng/ml (p<0.0001) at 3 months after the treatment. Contrast-enhanced T1-weighted MRI showed the disappearance of blood flow in all targeted regions of the prostate. MRI-TRUS fusion image-guided prostate biopsy detected the significant cancer out of the treated region in 1 patient. In urinary function, residual urine was significantly increased at 3 months after the treatment (p=0.007), but improved to the preoperative level (p=0.411). There was no significant deterioration in IPSS, IPSS QOL, OABSS, and the urinary function domain of EPIC between before and 3, 6, 9, and 12 months after the treatment. In sexual function, there was no significant difference in IIEF-5 and the sexual domain of EPIC between before and 3, 6, 9, and 12 months after the treatment. In quality of life, there was no significant difference in EPIC and SF-36 between before and 3, 6, 9, and 12 months after the treatment. The proportion of men with erections sufficient for penetration and ejaculation remained unchanged at 100% (5 of 5 patients). No serious adverse events were recorded. (Conclusions) The focal therapy with HIFU has the potential to provide accurate treatment with low morbidity in patients with localized prostate cancer. Further large studies are required to investigate the effects of the focal therapy with HIFU for analysis of oncological and functional outcomes in patients with localized prostate cancer.

Destructive effect of HIFU on rabbit embedded endometrial carcinoma tissues and their vascularities

OBJECTIVES

To evaluate damage effect of High-intensity focused ultrasound on early stage endometrial cancer tissues and their vascularities.

MATERIALS AND METHODS

Rabbit endometrial cancer models were established via tumor blocks implantation for a prospective control study. Ultrasonic ablation efficacy was evaluated by pathologic and imaging changes. The target lesions of experimental rabbits before and after ultrasonic ablation were observed after autopsy. The slides were used for hematoxylin-eosin staining, elastic fiber staining and endothelial cell staining; the slides were observed by optical microscopy. One slide was observed by electron microscopy. Then the target lesions of experimental animals with ultrasonic ablation were observed by vascular imaging, one group was visualized by digital subtract angiography, one group was quantified by color Doppler flow imaging, and one group was detected by dye perfusion.SPSS 19.0 software was used for statistical analyses.

RESULTS

Histological examination indicated that High-intensity focused ultrasound caused the tumor tissues and their vascularities coagulative necrosis. Tumor vascular structure components including elastic fiber, endothelial cells all were destroyed by ultrasonic ablation. Digital subtract angiography showed tumor vascular shadow were dismissed after ultrasonic ablation. After ultrasonic ablation, gray-scale of tumor nodules enhanced in ultrasonography, tumor peripheral and internal blood flow signals disappeared or significantly reduced in color Doppler flow imaging. Vascular perfusion performed after ultrasonic ablation, tumor vessels could not filled by dye liquid.

CONCLUSION

High-intensity focused ultrasound as a noninvasive method can destroy whole endometrial cancer cells and their supplying vascularities, which maybe an alternative approach of targeted therapy and new antiangiogenic strategy for endometrial cancer.

Evaluation of a small flat rectangular therapeutic ultrasonic transducer intended for intravascular use

BACKGROUND

The aim of the proposed study was to evaluate the performance of a flat rectangular (2×10mm²) transducer operating at 4MHz. The intended application of this transducer is intravascular treatment of thrombosis and atherosclerosis.

METHODS

The transducer's thermal capabilities were tested in two different gel phantoms. MR thermometry was used to demonstrate the thermal capabilities of this type of transducer.

RESULTS

Temperature measurements demonstrated that this simple and small transducer adequately produced high temperatures, which can be utilized for therapeutic purposes. These high temperatures were confirmed using thermocouple and MR measurements. Pulsed ultrasound in combination with thrombolytic drugs and microbubbles was utilized to eliminate porcine thrombi.

CONCLUSIONS

The proposed transducer has the potentials to treat atherosclerotic lesions using the thermal properties of ultrasound, since high temperatures can be achieved in less than 5s. The results revealed that the destruction of thrombi using pulsed ultrasound requires long exposure time and high microbubble dosage.