An Empirical Study Of Mongolian Gazelle Muscle Exposed To MR Imaging Guided High Intensity Focused Ultrasound

BackgroundRecently,several minimally invasive techniques have been introduced for the purpose of providing local control of some diseases and for the purpose of preserving the organs.One of these techniques,high intensity focused ultrasound (HIFU) as a novel method which offers the non-invasive ablation of tissues without harming the overlying organs has been widely used for the treatment of solid tumors including uterine fibroids,prostate cancer,breast cancer and so on.However,the clinical use of focused ultrasound surgery as a therapy has been hampered by the difficulty in precisely targeting the ultrasound beam and obtaining feedback about thermal damage.In terms of the real-time and post procedural assessment,the accurate evaluation of target response to therapy using imaging modalities is important for determining whether the tumor is completely treated or needs additional treatment.So it is very necessary to find a safe and effective monitoring system.Magnetic Resonance Imaging(MRI) has developed for more than 30 years.It is utilized in HIFU because of many advantages such as distinct imaging,high resolution, non-radiation damage and so on.Temperature-sensitive MR images obtained before,during and after a focused ultrasound sonication can be used to monitor tissue temperature elevations and prevent unwanted tissue damage with depiction of slight temperature elevations.In my study,I would choose the normal muscular tissue of southern xinjiang mongolian gazelle to be treated by MR imaging guided HIFU system.MRI Temperature-Map(T-Map) would be observed to prove the feasibility of the treatment of this system.ObjectiveTo explore the feasibility of the treatment system of MR imaging guided HIFU and study the relationship between adscendent temperature in T-Map and practical necrosis.Materials and methodsMR imaging guided HIFU thermocoagulation was carried out in normal muscular tissues of southern xinjiang mongolian gazelle. The parameters of therapeutic transducer were: frequency-1.0MHz,focal length-150mm,diameter-180mm.1.1 Exposure mode:dot. During the dot irradiating,the parameters were acoustic power-200W,exposure time-10S.And there were 80 dots in all.MRI T-Map was observed during the treatment and the regions of the adscendent temperature in T-Map were measured(blue:45~50℃,green: 50~55℃,yellow: 55~60℃,red: 60~110℃). The target tissues'histological changes were examined in comparison with normal.Meanwhile,the relationship between the adscendent temperature in T-Map and practical necrosis was compared. SPSS13.0 and excel statistical software were performed for the statistical analysis.1.2 Exposure mode:block. During the block irradiating,the treatment mode was continuous dot irradiation.There were 20 blocks whose size was 2×2×2 cm3. MRI T-Map was observed during the treatment and the regions of the adscendent temperature in T-Map were measured (blue:45~50℃,green: 50~55℃,yellow: 55~60℃,red: 60~110℃).The treatment was adjusted according to the T-Map.After the treatment,measure the practical tissue necrosis and compare it with the plan area and volume.And measure the area of the red region in T-Map,compare it with the area of the practical necrosis and the plan. SPSS13.0 and excel statistical software were performed for the statistical analysis.Results1. Macroscopical damages were made in all normal muscular tissues of southern xinjiang mongolian gazelle by dot irradiation after the treatment of MR imaging guided HIFU system. 2. During HIFU treatment,T-MAP shows a dynamic regularity,the temperature of focus went up expeditiously.At the end of the treatment,the temperature reached its peak value.Immediately,it descended to foundational temperature gradually. And just at the end of the treatment,a correlation existed between red region(60～110℃)and tissue necrosis(P>0.05) .3. After the block irradiation,a correlation existed between the areas and volumes of the practical necrosis and the plan(P>0.05).Conclusions1. Macroscopical damages can be made in all normal muscular tissues of southern xinjiang mongolian gazelle by MR imaging guided HIFU treatment system.2. MRI can be used as a real-time monitor to monitor the changes of the temperature of the focus during the HIFU treatment non-invasively. The red region can reflect the practical necrosis precisely.3 The treatment system of MR imaging guided HIFU can be used in the foundational empirical study. It is feasible and effective.