| BackgroundFrom the late20th century, the ultrasonic treatment technology has begun to rise internationally, Ultrasound treatment include high intensity focused ultrasound treatment and focused ultrasound treatment. HIFU sound intensity is generally from a few thousand to tens of thousands of watts per square centimeter, Due to it has the characteristic of minimally invasive; it has been widely used in the treatment of parenchymal Viscera and space-occupying tumor. Such as liver cancer, breast cancer, osteosarcoma, prostate cancer, uterine fibroids, soft tissue tumors and some metastatic tumors, etc. FU Sound intensity is generally from several tens to several hundred watts per square meter. Mainly use of the mech-anical, cavitation, thermal effect of ultrasonic and functional regulation to promote the formation of microvascular. Enabling to repair and regenerate the organizations, it has been widely used in the treatment of chronic cervicitis, nonneoplastic epithelial disorders of vulva, condyloma acuminatum of vulva, allergic rhinitis,etc. And obtain good effect. In addition to a wide range of applications in the treatment of a variety of solid tumors and Inflammation with ultrasonic treatment, it is also a major research focus in the field of fat loss shaping currently. The present study aimed to explore the destructive effect of FU to subcutaneous fat of pig In Vitro and In Vivo with the different irradiation dose. To evaluate the destructive effect on subcutaneous fat of pig and the skin lesions in the radiation area induced by HIFU, in order to explore the effective and safe irradiation dose interval and to provide experimental basis for fat remodeling in clinical application.ObjectiveThe present study aimed to explore the destructive effect of HIFU to subcutaneous fat of pig, To evaluate the destructive effect on subcutaneous fat of pig and the skin lesions in the radiation area induced by HIFU, it will provide experimental evidence for Fat loss shaping in clinical application using ultrasound, as well as supplement treatment technique for the Fat loss shaping area.Methods1. The experimental section In vitroFresh isolated pig fats with skin slaughtered within6hours (n=210, the average size of3×3×3cubic centimeters), Fresh pig fats divided into A and B groups, A=120(A1=60,A2=60), B=90(B1=60,B2=30). In group A, irradiation power was200W, irradiation time was5,10,20,30,60and90s respectively. In group B, irradiation power was200W, irradiation time was30,60and90s respectively.Through a number of criteria,such as the gross morphological changes of target areas were observed by visual inspection(group A1), thiazolyl blue tetrazolium bromide (MTT) staining was carried out and the volume of coagulation necrosis was calculated(group A2), and the target fats were sliced for microscopic observation(group B1), the temperatures before and after irradiation were measured in the skins and targets(group B2), in order to explore the destructive effective and provide safe irradiation dose for the subsequent experiments2. The experimental section In VivoTwo domestic pigs were numbered Ⅰ, Ⅱ(the weight was130～140kg), the irradiation area was Selected one in pig Ⅰ and two in pig Ⅱ with the thick subcutaneous fat, Ⅰ by the euthanasia time of day1after the irradiation and Ⅱ by the euthanasia time of day30after the two irradiations (one irradiation time was day1, the other irradiation time was day23).9selected irradiation doses were composed of the power of HIFU (100,150and200W) and the irradiation time (15、30and60s), each dose irradiated the subcutaneous fat at the same pig for on three different irradiation areas for once. The subcutaneous fats of the targeted area and the contrast area were collected then the macroscopic and histological observations were evaluated. Before and after (day2,7,23and30) the irradiation, Through Lipids before and after experiment, Take the target, the irradiated skin of vital organs (heart and liver) after the experiment to histological detection, the thickness of subcutaneous fat at the targeted area and the contrast area was detected by type-B ultrasonic in pig II.Result1. The experimental section In vitro(1)Focused ultrasound could destroy subcutaneous fat of pig in vitro effectively:Coagulation necrosis was not detected by visual inspection and MTT staining at the irradiation time of5s.(2)As the irradiation time≥10s, the necrosis volume and the histological changes of target region, temperature of target region and skin were correlated positively with the irradiation time.2. The experimental section In Vivo(1) Focused ultrasound could destroy subcutaneous fat of pig in vivo effectively:A gray-white coagulation necrosis was observed at the power of200W with the irradiation time of30s and60s in two pigs.(2)Except for the energy was too low to lead to the damaging effects of HIFU in the subcutaneous fat was not obvious, the pathological examination showed HIFU could destroy subcutaneous fat effectively and the destructive effect was positively correlated with the irradiation dose. The target tissue was took on the30th day after irradiation, the fibrosis was observed by Sirius red-polarization staining at the power of200W with the irradiation time of30s and60s, Light microscopic observation of important organs (heart and liver) normal morphology and no difference in the various lipid parameters in serum lipids before and after the experiment (P>0.05)(3)the fibrosis and foam cells was observed by electron Microscopic Observation at the power of200W with the irradiation time of60s without damaging the nerves and blood vessels outside the target.(4)Contrast to the contrast area, the reduction of the subcutaneous fat thickness at the targeted area was observed to varying degrees in all selected doses excepted the power of100W with the irradiation time of15s. The biggest reduction of the subcutaneous fat thickness presented at the power of200W with the irradiation time of60s.ConclusionFocused ultrasound could destroy subcutaneous fat of pig effectively without damaging the nerves and blood vessels outside the target, Experimental results indicated that the breakage of the subcutaneous fat presented conspicuously at the power of200W with the irradiation time of30s and60s. Compared with other parameters, the power of200W with the irradiation time of30s and60s could be Optimal Parameter. |
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