High-intensity focused ultrasound for the targeted destruction of uterine tissues: experiences from a pilot study using a mobile HIFU unit

Background High intensity focused ultrasound (HIFU) is a novel method which offers the non-invasive ablation of tissues without harming overlying organs or skin. It has been introduced successfully in urology for the ablation of prostatic hyperplasia and seems to be promising in the treatment of uterine fibroids. In this study we aimed to examine the feasibility and possible side effects of HIFU treatment of uterine tissues using an experimental mobile HIFU unit with ultrasound guidance. Methods For these experiments, a 1.07 MHz ultrasound source was used which allows treatment depths between 0 and 10 cm. In 12 patients scheduled to have abdominal hysterectomy, 5–60 impulses of HIFU were applied through the intact skin upon uterine tissues directly prior to the surgical procedure. Tissue intensities lay between 3,200 and 6,300 W/cm2 and a fixed pulse length of 4 s was used. Results No side effects were encountered other than one first-degree skin burn and the treatment was well tolerated. Histology showed clearly demarcated coagulative necrosis in the targeted tissues. Treatment was concluded in less than 45 min for each patient. Conclusion Focused ultrasound is an effective method to selectively destroy tissue within the uterus and the transabdominal access route is very feasible. This study shows that a mobile ultrasound source can be used safely and effectively to destroy uterine tissues, such as fibroids, without major side effects.     

相控型HIFU系统软件的开发与应用

介绍采用计算机图形学和数据库的相关技术,在自主研发的多阵元相控聚焦超声治疗设备上开发了一套可视化HIFU系统软件。经实验验证,该系统软件能够有效制定治疗规划,实施实验治疗方案,促进临床实验研究。     

Evaluation of color Doppler in guiding prostate biopsy after HIFU ablation

OBJECTIVE: Transrectal ultrasound cannot accurately depict early cancer recurrences after prostate high-intensity focused ultrasound (HIFU) ablation. We evaluated transrectal color Doppler (CD) in guiding post-HIFU prostate biopsy. METHODS: Prostate CD-guided sextant biopsies were obtained in 82 patients who had undergone prostate HIFU ablation for cancer, 24 of whom had hormone therapy before the treatment. At the time of biopsy, a subjective CD score was given to all biopsy sites (0=no flow; 1=minimal flow; 2=suspicious flow pattern). CD findings were compared with biopsy results. RESULTS: CD was a significant predictor of biopsy findings, according to univariate and multivariate site-by-site analysis. However, only 36 of 94 sites with residual cancer had positive CD findings, and thus, negative CD findings should not preclude random biopsy. There was a significant interaction between CD diagnostic capability and a history of hormone therapy before HIFU treatment. CD was a significant and independent predictor of biopsy findings in patients who had not received hormone therapy (odds ratio: 4.4; 95%CI: 2.5-7.9; p<0.0001), but not in those who had (odds ratio: 1.3; 95%CI: 0.5-3.4; p>0.5). CONCLUSION: Biopsy taken in CD-positive sites were 4.4 times more likely to contain cancer in patients who did not receive hormone therapy. CD could not reliably depict cancer recurrence in patients with history of hormone therapy.     

高强度聚焦超声终止小鼠妊娠的实验研究

目的:探讨高强度聚焦超声(H IFU)终止妊娠的可能性。方法:利用H IFU治疗机(780 kHZ)6种声强各60s体内直接照射妊娠第7天小鼠胚胎,妊娠15 d时观察各组胚胎死亡率和胎盘、子宫的形态学变化。结果:对照组胚胎总死亡率为12.65%(32/253);照射组中声强3 W/cm2、6 W/cm2及≥9 W/cm2组的胚胎死亡率分别为25.00%(12/48)、72.88%(43/59)和100%(64/64、43/43、40/40、35/35)。超声照射后8 d的改变:光镜下主要为胎盘出血、变性、坏死;电镜下胎盘组织细胞坏死呈致密团块状,子宫改变轻微。变化随剂量的增加而明显。结论:胎盘较子宫对H IFU更敏感,更易受损,H IFU抗早孕具有潜在的可行性,值得进一步研究。     

热消融治疗肿瘤的研究进展

伴随现代医学成像技术的快速发展,影像引导热消融技术在越来越多的肿瘤治疗中发挥着不可替代的作用。本文综述了热消融技术的基本细胞学机制,介绍了五种最常见的热消融技术——射频消融（Radiofrequency Ablation, RFA）、微波消融（Microwave Ablation, MWA）、冷冻消融（Cryoablation, CA）、高强度聚焦超声（High-intensity Focused Ultrasound, HIFU）、激光消融（Laser Ablation, LA）,包括各自的基本原理和优缺点,以期指导临床热消融技术的进一步推广和应用。     

高强度聚焦超声治疗子宫肌瘤的因素及5年疗效评价

目的探讨高强度聚焦超声(HIFU)治疗子宫肌瘤的因素及5年疗效评价。方法利用HIFU治疗子宫肌瘤患者191例,肌瘤260个。在超声定位实时监视下,从体外将高能量超声聚焦于子宫肌瘤内,治疗后,定期随访观察患者临床症状、体征及瘤体超声影像学变化。结果260个子宫肌瘤,有205个经HIFU治疗后,5年总效率84.2%,无效率15.8%。因子宫肌瘤部位、大小、靶皮距等因素不同,且疗效亦不同。结论HIFU治疗子宫肌瘤只要病例选择正确、方法得当,会取得满意的疗效。     

Treatment monitoring and thermometry for therapeutic focused ultrasound

Therapeutic ultrasound is currently enjoying increasingly widespread clinical use especially for the treatment of cancer of the prostate, liver, kidney, breast, pancreas and bone, as well as for the treatment of uterine fibroids. The optimum method of treatment delivery varies between anatomical sites, but in all cases monitoring of the treatment is crucial if extensive clinical acceptance is to be achieved. Monitoring not only provides the operating clinician with information relating to the effectiveness of treatment, but can also provide an early alert to the onset of adverse effects in normal tissue. This paper reviews invasive and non-invasive monitoring methods that have been applied to assess the extent of treatment during the delivery of therapeutic ultrasound in the laboratory and clinic (follow-up after treatment is not reviewed in detail). The monitoring of temperature and, importantly, the way in which this measurement can be used to estimate the delivered thermal dose, is dealt with as a separate special case. Already therapeutic ultrasound has reached a stage of development where it is possible to attempt real-time feedback during exposure in order to optimize each and every delivery of ultrasound energy. To date, data from MR imaging have shown better agreement with the size of regions of damage than those from diagnostic ultrasound, but novel ultrasonic techniques may redress this balance. Whilst MR currently offers the best method for non-invasive temperature measurement, the ultrasound techniques under development, which could potentially offer more rapid visualisation of results, are discussed.     

A feasibility study for non-invasive thermometry using non-linear ultrasound

Purpose: High intensity focused ultrasound (HIFU) is used during hyperthermia cancer treatment to increase the tumour temperature. For an adequate and safe application it is important to measure the temperature in the heated region, preferably in a non-invasive manner and by the same modality as used for heating. The goal of this feasibility study is two-fold; first, it is investigated whether the acoustic non-linearity parameter B/A is most suitable for measuring temperature changes, second, a non-invasive thermometry method based on B/A is proposed and demonstrated.

Material and methods: Water is used to confirm that B/A is a sensitive acoustic medium parameter that is practically applicable for non-invasive thermometry. Next, a thermometry method is proposed that employs the ratios between the fundamental and the higher harmonic frequency components of a non-linear acoustic wave. The method determines these ratios for a measured acoustic pulse that has traversed a certain medium, and compares these with temperature dependent reference ratios for the same medium. The method is demonstrated using simulated measurements of an acoustic plane wave propagating in glycerol.

Results: Results obtained for water show that B/A is more sensitive for temperature changes than other practical acoustic parameters. For a combination of 16 simulated measurements, it is demonstrated that temperature can be predicted non-invasively with zero bias and a standard deviation of 2°C if the noise level does not exceed ?40?dB.

Conclusion: The suitability of B/A as a basis for non-invasive thermometry is confirmed, and a non-invasive thermometry method based on B/A is proposed and successfully demonstrated.