To Investigate The Significance Of A Novel Blood Flow Assessment Of Radiofrequency Ablation Of Benign Thyroid Nodule:CEUS In MSMI Mode

Background and Objective:In recent years,with the development of technology and the popularization of physical examination,the detection rate of thyroid nodules has increased greatly,most of which are benign nodules.Some benign thyroid nodules need not be treated,but can be followed up regularly.But when some larger nodules cause cervical discomfort and other symptoms,clinical intervention is needed.Radiofrequency ablation is a good choice for the treatment of nodules,and the safety and effectiveness of the treatment are also acceptable.Ultrasound-guided radiofrequency ablation for benign thyroid nodules should destroy as much blood flow as possible on the basis of ensuring safety.Therefore,before and after radiofrequency ablation,a method that can show the real blood flow in nodules is very important in clinic.Because Color Doppler(CDFI)is not good at displaying small vessels and low velocity blood flow,and Contrast-Enhanced Ultrasound(CEUS)is good for large,small vessels and high and low velocity blood flow,AACE,AME,ETA and other guidelines recommend using CEUS to evaluate blood flow in nodules after primary ablation.In the consensus reached by experts on some common clinical problems of thyroid ultrasound in China in 2018,experts also affirmed the value of CEUS in ultrasound-guided radiofrequency ablation of benign thyroid nodules.Monochrome Superb Microvascular Imaging(mSMI)uses a unique algorithm to non-invasively display tiny blood vessels and low-speed blood flow.Whether mSMI,a free flow assessment method without contraindication,can achieve the same effect as CEUS in assessing the real blood flow in thyroid benign nodules before and after ultrasound-guided radiofrequency ablation? Contrast-Enhanced Ultrasound in the Context of monochrome Superb Microvascular Imaging(CEUS+mSMI)is a new blood flow assessment method that we accidentally discovered when trying to improve CEUS.In this mode,some tiny blood vessels that are difficult to display during CEUS are clearly displayed.What are the characteristics of this mode compared with CEUS alone? Can this new technique better guide ultrasound-guided radiofrequency ablation of benign thyroid nodules? With these questions,we designed this experiment.Materials and Methods:Fifty patients with solitary solid or cystic solid nodules of nodular goiter confirmed by puncture pathology in our hospital from March to December 2017 were selected.CDFI,mSMI,CEUS,CEUS+mSMI were used to evaluate and grade the blood flow signals in thyroid benign nodules before and after ultrasound-guided radiofrequency ablation.The signal display rate of blood flow in nodules was calculated and analyzed statistically.Result:Before ultrasound-guided radiofrequency ablation of benign thyroid nodules: CEUS+mSMI,CEUS and mSMI showed higher blood flow in grade III than CDFI [90.00%(45/50),34.00%(17/50),28.00%(14/50),6.00%(3/50)].CEUS and mSMI had a good agreement on the classification of blood flow signals in the nodules.The weighted Kappa coefficient of the two was 0.630(95% CI was 0.437-0.815,P<0.001).The consistency of CEUS and CEUS+mSMI in grading intranodular blood flow signals was poor.The weighted Kappa coefficients of CEUS and CEUS+mSMI were 0.191(95% CI was 0.027-0.355,P < 0.001).After the first radiofrequency ablation:We can't exclude the interference of hyperechoic gases in mSMI mode to evaluate the blood flow in nodules,CEUS + mSMI and CEUS showed a lower level 0 blood flow than CDFI [16.00%(8/50),18.00%(9/50),64.00%(32/50)],there was significant difference between CEUS and CEUS + mSMI in the classification of intranodular blood flow signals(P < 0.001).Conclusion:1.mSMI can provide blood flow information comparable to CEUS before ultrasound-guided radiofrequency ablation of benign thyroid nodules.We can use mSMI instead of CEUS to evaluate blood flow in nodules before operation.However,after ultrasound-guided radiofrequency ablation of thyroid nodules,we can't exclude the interference of hyperechoic gases in mSMI mode to identify blood flow,so we can't use mSMI to evaluate the survival of residual small vessels in thyroid nodules after operation.2.Before and after radiofrequency ablation of benign thyroid nodules,CEUS+mSMI evaluated the blood flow in the nodules better than CEUS alone.Some of the small blood flow that was not shown in CEUS mode was clearly displayed in CEUS+mSMI.CEUS+mSMI can better guide the radiofrequency ablation of thyroid nodules.