The Value Of Magnetic Resonance Imaging In Uterine Fibroids After Low-power High-Intensity Focused Ultrasound Ablation

Objective: To analyze the value of 1.5T magnetic resonance imaging in evaluating the efficacy and prognosis of uterine fibroids after low-power high intensity focused ultrasound ablation.Methods: 350 cases of uterine fibroids underwent noncontract and contrast-enhanced MRI scans before and after low-power HIFU treatment.Their MRI images were retrospectively collected and recorded the number,diameter,position,type and MRI T₂ WI signal of the fibroids before low-power HIFU ablation.350 cases with 390 uterine fibroids were followed up regularly,using the same sequence and scanning parameters to scan after 1 day,3 months,12 months.23 patients among them,the absolute signal intensity?ASI?,the signal contrast to noise ratio?CNR?,signal intensity ratio?SIR?of uterine leiomyomas and uterine walls were measured on T₁ WI,T₂WI and contrast-enhanced images before and after treatment.Result: This study collected 350 cases with 390 uterine fibroids.No severe complication in all patients during and after the operation.Postoperative enhanced magnetic resonance shows all the ablation lessons showed significant no perfusion area,the rim enhancement,the blood supply of uterine fibroids were occluded.In 350 cases with 390 uterine fibroids of regularly follow-up:1.located on the anterior wall,posterior wall,side wall are respectively accounted for 42.31%?165/390?,38.97%?152/390?,18.72%?73/390?,postoperative leiomyoma ablation rate have no significant relationship?F=0.004,P=0.103?.2.390 fibroids in 350 patients were classified into 3 types based on the types of fibroids as follows: type 1,submucosal leiomyoma;type 2,intramural leiomyoma;type 3,subserous leiomyoma,are respectively accounted for 28.21%?110/390?,39.49%?154/390?,32.31%?126/390?,postoperative leiomyoma ablation rate have no significant relationship with fibroids' types?F=0.085,P=0.084?.3.390 fibroids in 350 patients were classified into 4 types based on the size of fibroids as follows: type 1,fibroids less than three centimeters in diameter;type 2,fibroids are between three and six centimeters in diameter;type 3,fibroids are between six and nine centimeters in diameter;type 4,fibroids are between nine and twelve centimeters in diameter,are respectively accounted for 18.97%?74/390?,33.59%?131/390?,28.21%?110/390?,19.23%?75/390?,postoperative leiomyoma ablation rate have no significant relationship with fibroids' size?F=0.109,P=0.203?.4.390 fibroids in 350 patients were classified into 4 types based on the signal intensity of T₂ –weighted magnetic resonance images as follows: type 1,low intensity;type 2,intermediate intensity;type 3,high intensity;type 4,mixed intensity,are respectively accounted for 51.54%?201/390?,10.77 %?42/390?,20.77%?81/390?,16.92%?66/390?,postoperative leiomyoma ablation rate have significant relationship with fibroids' signal intensity of T₂–weighted magnetic resonance images?F=10.394,P=0.001?,volume reduction ratio of type 1 fibroids was the highest among the 4 types.5.ASI,CNR,SIR of uterine fibroid measured on contrast-enhanced T₁ WI and ASI,SIR of uterine fibroid measured on T₁ WI,T₂WI before low-power HIFU treatment had significant difference compared with that after low-power HIFU treatment,[T₁-weighted images?ASI: t=-2.553,P=0.017;SIR: t=-4.118,P=0.000?,T₁-weighted enhancement images?ASI: t=13.868,P=0.000;CNR: t=-0.908,P=0.000;SIR: t=19.176,P=0.000?,T₂-weighted images?ASI: t=-2.569,P=0.000;SIR: t=-2.235,P=0.003?],CNR of uterine fibroid measured on T₂ WI and T₁ WI had no significant difference between before and after low-power HIFU treatment[T₁-weighted images?CNR: t=-0.973,P=0.340?,T₂-weighted images?CNR: t=0.860,P=0.555?].ASI of uterine wall measured on T₁ WI,contrast T₁ WI,and T₂ WI before low-power HIFU treatment had no significant difference compared with that after low-power HIFU treatment.[T₁-weighted images:?t=-0.568,P=0.575?,T₂-weighted images:?t=-0.518,P=0.199?,T₁-weighted enhancement images:?t=0.400,P=0.557?].Conclusions:1.The efficacy of HIFU in the treatment of uterine fibroids is related to the MRI-T₂ W signal intensity of fibroids and has nothing to do with the size,location,type,etc.of uterine fibroids.Signal intensity on T₂ WI can be used as a predictor for HIFU for uterine fibroids.2.ASI of uterine fibroids in MRI can be altered after lower-power HIFU.ASI can be used as a predictor for HIFU for uterine fibroids.3.1.5 T MRI has perfect soft,tissue resolution and can be used as a noninvasive method in monitoring treatment effectivity of low-power HIFU.