Background

By means of the characteristics of ultrasound such as strong penetrability, perfect directionality and self-focusing, HIFU (high intensity focused ultrasound) transmitted from the outside of body can pass through soft tissue and focus at the lesions in the body (target); owing to powerful energy deposition in the place at which ultrasound focus, so the temperature in the local tissues can rise to more than 60¡æ which will lead to irreversible cell death and coagulative necrosis; therefore, it can resect the lesions without any damage on the surrounding normal tissues, and thus the targeted destruction of?lesions can be achieved by it finally. This article will introduce the applications of HIFU technology in the gynecological?diseases such as hysteromyoma, vulvae non-epithelial tumor?and cervicitis etc. 

HIFU treatment of hysteromyoma

HIFU is a non-invasive conformal therapy (does not need laparotomy and centesis) and the therapeutic range of it can be adjusted according to the sizes of hysteromyoma, so it belongs to a kind of minimally invasive (non-invasive) technology. Recent years, B-mode ultrasonography-guided HIFU therapy on hysteromyoma has been applied widely in clinical treatments and it has been accepted easily by patients in that its affordable price. At present, 2,000 patients (average age:45.5) with hysteromyoma has been accepted the clinical application study of HIFU therapy in the Haifu Clinical Research Centers, of which 978 cases had symptoms related to hysteromyoma; as of October 2007, follow-up time?has reached to 2 months to 5 years and the average diameter of hysteromyoma was 7.5cm. In the process of HIFU therapy, we monitored it with B-mode ultrasonography and designed target region treatment levels?of hysteromyoma according to sonograms so as to make the focused ultrasound can cover and scan the target region layer by layer. At the same time, the gray levels of each layer before and after treatment have been compared by the ultrasound and we regarded increased gray level as effective treatment (treatment time: 1-3h). The results from the study showed that the gray levels of target regions changed obviously in the course of HIFU radiotherapy; moreover, after treatment, patients’ symptoms such as menorrhagia, menostaxis, lumbosacral heaviness and distension etc have been relieved without any side effects; imaging follow-up found that the sizes of tumor reduced gradually until they disappeared completely and the average size of necrotic menorrhagia was not less than 85%. The results above proved that a safe and effective treatment on menorrhagia could be offered by HIFU therapy which was practicable in clinical application; moreover, B mode ultrasound could be used in the real time monitoring of treatment so as to ensure the efficiency and the security of ultrasonic therapy. HIFU technology is conducive to retain the normal functions of uterus without any impacts on ovarian endocrine function; in addition, in the aspect of improvement of clinical symptoms, HIFU therapy is equivalent to gynecologic resection, and thus this hopeful non-invasive treatment will be expected to become a new way for the treatment of menorrhagia.

HIFU treatment on non-cancerous gynecological diseases

The Engineering Research Institute for Medical Ultrasound of Chongqing Medical University has carried out more than 5 years of basic researches on physical characteristics of ultrasound, the biochemical characteristics and the changes in biological tissues (including pathological, physiological and biochemical changes) after the interaction of ultrasound and biological tissues: by means of a number of studies such as histological, immunohistochemical, enzymatic experiments and ultrastructural observation etc, they studied the principles of ultrasound in the treatment of vulvae non-epithelial tumor, proved that ultrasound could change effectively the structures of epidermal and dermal layers of vulvae; in addition, it could also improve the microcirculation of local tissues and the nutritional status of Nerve endings; moreover, it caused any damage on skins in the process of treatment, and thus vulvae non-epithelial tumors could be treated by it successfully. By means of large numbers of animal experiments, they defined the parameters of ultrasound treatment (including ultrasonic frequency, power, scanning mode and scanning speed etc), established the relationship between energy and efficiency of ultrasound treatment; at the same time, based on the experiments above, they carried out multi-center clinical trials?and made use of histopathological prognosis and curative effects to analyze and demonstrate the safety and efficacy of ultrasound treatment.

Since May 1999, HIFU therapy was adopted first by the cancer treatment center and the department of gynaecology and obstetrics of Second Affiliated Hospital of Chongqing Medical University and the first case of vulvae non-epithelial tumor was treated successfully by them; up to September 2002, 80 cases of similar patients have been treated. The results from the clinical researches showed that the skin itch of these patients could be relieved even eliminated; in addition, the elasticity and color of skins of vulvae returned to be normal basically; the effective rate of treatment was more than 95%.At the same time, by means of comparing the pathological changes in the tissues before and after HIFU treatment, they found that the structures of epidermal and dermal layers of vulvae returned to be normal gradually; moreover, distinctly increased pigment deposition could be found at the basal layer of epidermis. These results above have established the histological basis for the evaluation of clinical efficacy of ultrasound treatment. The treatment principle of HIFU therapy can be explained as follows: focusing ultrasonic beams on the target tissues (dermal layer); making use of a series of effects of ultrasound such as mechanical, thermal, cavitation, sonochemical and functional regulation effects to promote the formation of blood capillaries of local tissues, increase the permeability of vascular endothelial cell membrane, change the micro-environment in which local tissues grow, improve the microcirculation of local tissues and the nutritional status of Nerve endings, promote the repair and regeneration of local tissues and thus the skin lesions on the vulva can be rehabilitated finally. At the same time, this study also showed that ultrasound treatment could not only cure effectively refractory pruritus vulvae, but also make the color of skin lesions to return to be normal; in addition, the integrity of the skin could be maintained in the process of treatment, therefore, HIFU therapy is a new and effective method for the treatment of vulvar intraepithelial non-cancerous lesions. 

HIFU therapy has been adopted first by the cancer treatment center of Second Affiliated Hospital of Chongqing Medical University and the department of gynaecology and obstetrics of the First People’s Hospital of Jiangbei District of Chongqing; from January to May in 2003, CZF-type ultrasonic therapeutic equipment has been adopted by them to carry out a clinical research on the treatment of 80 cases of patients with chronic cervicitis. The results showed that the total effective rate of HIFU therapy reached to 92%; in addition, scar formation, shed tissues and vaginal bleeding could not be found in the course of treatment, which showed that this HIFU therapy will provide a new way for clinicians to treat chronic cervicitis in the near future. Comparing with laser treatment, although the curative effects of two treatments had no significant difference, however, the incidence rate of vaginal bleeding among HIFU therapy group was obviously lower than that of the laser treatment group. The data from Jiangxi Province Maternal and Child Health Hospital also showed that HIFU therapy could treat cervical hypertrophy effectively and 90% of cervix could return to its normal size. Nowadays, with the continuous optimization?of clinical treatment programs and the improved clinical efficacy of HIFU on the treatment of chronic cervicitis, the CZF-type ultrasonic therapeutic equipment?has been adopted by more than 600 hospitals in China.