Studies On Energy Prediction Before Microwave Ablation For Uterine Fibroids With New Ultrasonic Technology And Its Mechanism

PurposesTo investigate the feasibility of predicting percutaneous microwave ablation (PMWA) energy for uterine fibroids by three-dimensional power Doppler ultrasonography (3D-PDUS) and study the relationship between different vascularization flow index (VFI) value of 3D-PDUS and quantitative microwave ablation range for uterine fibroids; To study the mechanism of energy prediction before microwave ablation for uterine fibroids with 3D-PDUS; To investigate the feasibility of predicting PMWA energy needed for uterine fibroids by ultrasound elastography.Materials and MethodsPatients with uterine fibroids underwent conventional color Doppler,3D-PDUS, ultrasound elastography and pelvic contrast-enhanced MRI (ceMRI) scan before ultrasound-guided PMWA treatment from March 2014 to December 2015 in PLA general hospital. Then blood supply grading of uterine fibroids were done and VFI value was calculated through VOCAL software; Uterine fibroids and normal tissue around the same level were traced and calculated on Q-analysis system to obtain the elasticity value and elasticity ratio value; Taking the uterine myometrium and musculue skeleti SI of MR T2W1 as reference stantard, uterine fibroids were classified as hypointense, isointense and hyperintense. Uterine fibroids whose diameters were more than 5 cm were treated with quantitative ablation energy of 50 w x 300 s and Tlla single antenna was used. Non-perfused volume (NPV) and range of contrast-enhanced ultrasound (CEUS) was measured immediately after ablation as the volume and range of quantitative ablation.1) Relationship between VFI value of 3D-PDUS and quantitative microwave ablation volume was analyzed statistically; Quantitative ablation range of uterine fibroids of different blood supply grading and different range of VFI value was analyzed.2) The relationship between VFI value of 3D-PDUS and T2WI SI was analyzed.3) Relationship between elasticity value?elasticity ratio value and quantitative microwave ablation volume was analyzed statistically.ResultsA total of 120 uterine fibroids in 110 patients were included. Of 120 fibroids,66 fibroids (110 patients) underwent quantitative microwave ablation.1. Energy prediction before microwave ablation for fibroids with 3D-PDUS:66 uterine fibroids underwent quantitative microwave ablation with average VFI value of 1.97± 1.78 and average ablation volume of 36.65 ±21.71 cm3; the quantitative ablation volume was negatively correlated with VFI (r=-0.448,p=0.007). As VFI increased, the ablation volume decreased under the same microwave ablation energy. According to blood supply grading that corresponds to the range of VFI value, uterine fibroids were divided into three groups:0-0.999(grade I), 1-2.699(grade II), 2.7-7.999(grade III), and number of fibroids was respectively 26,18,22. For the same microwave energy, ablation range was smaller with higher blood supply grading and bigger VFI value. The differences in quantitative ablation range among three groups were statistically significant(p<0.05), the differences of two-two comparisons were all statistically significant(p<0.05).2. The mechanism of energy prediction for uterine fibroids with 3D-PDUS:T2WI SI of 120 uterine fibroids were analyzed, and number of hypointensity group, isointensity group, hyperintensity group were 48,30,32, respectively; The average VFI value of uterine fibroids were 0.64 ±0.27,1.23 ±0.43 and 2.72 ±2.13, respectively; The differences in VFI among the three groups were statistically significant (F=9.406, p< 0.05), and the differences were statistically significant by the two-two comparisons (p< 0.05).3. Energy prediction for uterine fibroids with ultrasound elastography:66 fibroids underwent quantitative microwave ablation with average elasticity value of 2.75 ±0.89, average elasticity ratio value of 1.81 ± 1.05 and average ablation volume of 36.65 ± 21.71 cm; Elasticity value and elasticity ratio value were not correlated with quantitative ablation volume (r=0.1673,0.1983; p=0.302,0.220).Conclusions1. For the same PMWA energy, ablation volumes of uterine fibroids with higher VFI were smaller; VFI value of 3D-PDUS can preliminarily predict energy required for PMWA. Blood flow parameters VFI of 3D-PDUS have consulted value for clinical predicting PMWA energy and preoperative planning of uterine fibroids.2. Blood flow parameters VFI of 3D-PDUS can reflects the blood flow of the lesion and affect the rise of tissue temperature during ablation, so it can predict PMWA energy for uterine fibroids.3. Ultrasound elastography can not be used to predict PMWA energy required for uterine fibroids.