| Uterine fibroids are the most common benign tumors of the female reproductive system,and the presence of their symptoms seriously affects the physical and mental health of women of childbearing age.With the continuous progress of medical concept and technology,HIFUa has gradually become one of the main methods for the treatment of uterine fibroids.MRI has the characteristics of high resolution for soft tissue lesions,and can clearly provide information on the location,size and changes of fibroid after surgery.It plays an important role in predicting the surgical effect before HIFUa ablation of uterine fibroid and evaluating the curative effect after surgery.Generally,the T2WI SI of uterine fibroids is classified into three categories:low signal intensity close to rectus abdominis,equal signal intensity higher than rectus abdominis but lower than myometrium,and high signal intensity equal to or higher than myometrium,which leads to the conclusion that the ablation rate of fibroids with high signal intensity on T2WI is lower than that with low signal.Previous classification methods are comparative qualitative analysis,and there is subjective bias.The judgment of the same group of MR images often differs between different doctors,which limits its clinical application.This study evaluates the predictive effect of T2WI SI value on the efficacy and dose of fibroid ablation more objectively by quantitatively detecting the SI value of fibroid,and obtains a dosimetric model,which provides a basis for clinical precise dose delivery and dose control.Objective:To evaluate the relationship between MR T2WI signal value and the efficacy of HIFUa ablation of uterine fibroids by quantitatively detecting the MR T2WI signal intensity value of uterine fibroids,and to study the value of T2WI signal value of uterine fibroids for predicting the effect of ultrasound ablation.Based on multi-dimensional clinical variables,a multi-factor dose prediction model including T2WI signal value of uterine fibroid was established with energy efficiency factor?EEF?as the ultrasound dose dimension to provide a method and basis for accurate prediction of ultrasound dose before HIFUa ablation of uterine fibroid.Method:From January 2016 to December 2018,307 patients with uterine fibroids underwent HIFUa ablation in the First Affiliated Hospital of Chongqing Medical University.The DICOM format of the preoperative MR image files of the patients with uterine fibroids was imported into the software system for automatic quantitative detection,and the relationship and predictive value between the MR T2WI signal intensity value of uterine fibroids and the efficacy of HIFUa ablation were analyzed.With the ablation rate of uterine fibroids reaching 70%or more as the ablation target,a predictive model was constructed by logistic multivariate regression analysis.Data of 442 patients who underwent ablation at Haifu Treatment Center of the First Affiliated Hospital of Chongqing Medical University from January 2015 to May 2019 were included.The MR T2WI signal value of uterine fibroid were measured by software.With EEF as dependent variable and 12 factors that may affect the dose delivery of ultrasound ablation:age,BMI,uterine location,type of fibroid,location of fibroid,volume of fibroid,skin distance from ventral side of fibroid,skin distance from dorsal side of fibroid,sacrococcygeal distance from dorsal side of fibroid,abdominal wall thickness,enhancement type,SI fibroid and SD fibroid as independent variables,stepwise regression method was used.Significant independent variables were screened and dose prediction models were established.Result:The MRI T2WI SI value of 307 uterine fibroids was 298.17±115.41?85.67-769.00?,with an average ablation rate of 75.74%±18.48%?4.00%-100.00%?.According to the segmental analysis of T2WI SI values,the average ablation rates of uterine fibroids from low to high SI values were:SI<200200 group?84.00±13.97?%,SI200-30000-300 group?78.67±15.38?%,SI300-400group?70.71±19.15?%,SI?400400 group?68.07±21.82?%,respectively,with significant differences among the four groups?H=34.791,P=0.000?.The probability of 70%fibroid ablation rate with SI of 100,200,300,400,500,600,700 was 83.00%,78.00%,72.00%,63.00%,54.00%,46.00%,30.00%,respectively,and its prediction sensitivity 77.20%,specificity 54.90%.The ablation target was 70%or more of the volume of uterine fibroids.Significant variables included patient age,BMI,and T2WI signal value of fibroids.The predictive model for the ablation rate of uterine fibroid volume of more than 70%was?=2.966+0.088×X1-0.124×X2-0.008×X3?X1=age,X2=BMI,X3=fibroid T2WI SI?.The cut-off value was 0.447,the area under the ROC curve was 0.751,95%CI[0.694,0.807],sensitivity0.913,specificity 0.564.The average MRI T2WI SI value of 442 uterine fibroids was299.47±119.89?85.67-899.00?,and the average SD value of fibroids was55.89±27.74?16.96-212.57?.The significant influencing factors for EEF were uterine location?rs=0.227,P=0.000?,fibroid location?rs=0.195,P=0.000?,,fibroid dorsal distance to sacrococcyx?rs=0.203,P=0.000?,SI fibroid?rs=0.156,P=0.001?,SI fibroid-rectus abdominis?rs=0.193,P=0.000?,age?rs=-0.154,P=0.001?,fibroid volume?rs=-0.473,P=0.000?,SI myometrium-fibroid?rs=-0.210,P=0.000?,SI intima-fibroid?rs=-0.223,P=0.000?.Taking EEF as the dosimetric dimension,the dose prediction model was obtained:?=0.308X1+0.215X2+0.149X3-0.159X4+0.128X5+0.106X6(?=EEF,X1=fibroid volume,X2=distance of ventral side of fibroid from skin,X3=SI fibroid,X4=age,X5=fibroid location?1=anterior wall,2=posterior wall,3=lateral wall?,X6=BMI).Conclusion:Quantitative analysis of MR T2WI SI of uterine fibroid can more objectively evaluate and predict the effect of HIFU ablation of uterine fibroid.Multivariate prediction model based on fibroid SI has high prediction sensitivity and good prediction effect for the effect of HIFU ablation of uterine fibroid,which can provide a basis for the preoperative evaluation of the efficacy of HIFUa for uterine fibroid.Multivariate dosimetric model with EEF as dependent variable can provide basis for clinical precise dose delivery and dose control. |
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