MRI Evaluation Of Uterine Fibroids Near Sacral Tail After Ultrasound Ablation And Its Influencing Factors

Uterine fibroids are the most common benign tumors of female reproductive system.Nowadays,high intensity focused ultrasound(HIFU)has become one of the main treatment methods for uterine fibroids.Previous studies have confirmed that HIFU treatment is safe and effective.However,due to the characteristics of ultrasonic mechanical wave,it will produce refraction,reflection,cavitation effect,thermal effect,etc.,which will cause damage to the surrounding non-target tissues and produce postoperative adverse reactions.The uterine fibroids adjacent to the sacrococcygeal region are located in the deep pelvic cavity,and the acoustic channels,as well as surrounding tissues are complex,making it more difficult to ablate.Compared with other parts of uterine fibroids,they need more energy and are more likely to cause damage to surrounding tissues.Therefore,the safety of ultrasonic ablation of uterine fibroids adjacent to the sacrococcygeal region has always been the focus of clinical attention.The purpose of this study was to evaluate the damage(reaction)of the surrounding tissues after ultrasound ablation of uterine fibroids adjacent to the sacrococcygeal region by MRI,and to analyze the influencing factors of sacrum injury(reaction),so as to provide a basis for the clinical treatment of uterine fibroids adjacent to the sacrococcygeal region by ultrasound.Purpose:1.To study the ablation of target area after ultrasound ablation for uterine fibroids adjacent to the sacrococcygeal region,as well as the MRI imaging characteristics and injury(reaction)in non-target area.2.To study the sacrum injury and influencing factors after ultrasonic ablation of uterine fibroids adjacent to the sacrococcygeal region.Methods:1.A total of 258 patients with uterine fibroids who received ultrasound ablation in the First Affiliated Hospital of Chongqing Medical University from January 2016 to December 2018 were collected,including 258 uterine fibroids.By comparing the preoperative and postoperative MRI imaging features,the ablation of the target area and the injury(reaction)of the non-target area were observed.2.A total of 406 patients with uterine fibroids who underwent ultrasound ablation in the First Affiliated Hospital of Chongqing Medical University from January 2014 to December 2018 were analyzed.All patients underwent contrast-enhanced magnetic resonance imaging(CE-MRI)scans before and after surgery.According to whether there was abnormal signal on postoperative MRI images(low signal intensity on T1 WI and high signal intensity on T2WI),The patients were divided into sacrum injury and sacrum no-injury groups.Univariate and multivariate analyses were used to assess the association of sacum injury(reaction).Results:1.The ablation of uterine fibroids: Postoperatively,the volume of non-perfusion area was 15.54-326.95 cm3,with an average of(85.18±65.12)cm3,and the ablation rate was 25.12%-100%,with an average of(71.22±17.96)%.There were 27 cases(10.47%)of endometrium injury(reaction),30 cases(11.63%)of serous membrane(sarcomuscular-layer)injury(reaction),83 cases(32.17%)of sacrum injury(reaction),22 cases(8.53%)of abdominal wall injury(reaction),and 42 cases(16.28%)of pelvic effusion.2.There were 139 cases of sacral injury(reaction)(34.24%).Multivariate logistic regression analysis showed that the distance between the dorsal side of fibroid and the sacrum and the treatment dose were significantly correlated with the sacral injury(P < 0.05).Among them,the risk of sacrum injury was 1.85 times and 3.03 times when the distance from the dorsal side of fibroid to the sacrum was 0-10 mm,compared with that of 11-20 mm and 21-30 mm.And the risk of sacrum injury was 1.89 times and 3.23 times when the therapeutic dose(TD)of fibroid was more than 500 k J,compared with that of fibroid with TD = 250-500 k J and < 250 k J.Conclusion:1.Uterine fibroids adjacent to the sacrococcygeal region can be successfully ablated by ultrasound,but there is a risk of injury(reaction)to the surrounding tissues.2.The distance between the dorsal side of the fibroids and the sacrum,and the treatment dose were independent influencing factors of sacrum injury(reaction).