Exploration On The Value Of Ultrasonic Elastography In Evaluating Microwave Ablation

Part ? Observation of the lesions after microwave ablation on pork liver in vitro by two ultrasonic elastography methodsObjectiveTo compare the differences between the values measured by ultrasound(US)and spin echo(SE)in the microwave ablation range in pork liver in vitro and the actual value of specimen,as well as to observe the variation of values measured by US and SE with the time extension post ablation;To explore the variation of tissue hardness and temperature of ablation lesion by measuring the shear wave elastography(SWE)value and temperature of microwave ablation lesion in pork live in vitro.Methods1.Group:According to power and duration,the ablation were divided into 3 groups,45w30s was group 1,45w15s was group 2,30w30s was group.The observation time point was immediately,5 min,30 min and 1 h post ablation,respectively.2.Diameter measurement:?The US was used to measure the largest transverse diameter(D1),vertical diameter(D2)and anteroposterior diameter(D3)of ablation lesion post ablation of pork liver in vitro.?The UE was also used to measure the largest transverse diameter(SEL1),vertical diameter(SEL2)and anteroposterior diameter(SEL3)of ablation lesion.?The ablation lesion was slit and its largest transverse diameter(L1),vertical diameter(L2)and anteroposterior diameter(L3)were measured.3.SWE and temperature measurement:?The SWE value and temperature of normal pork liver before ablation were measured.?The SWE value of central lesion(SWEa),SWE value of marginal area(SWEb)after ablation,and the SWE value of unablated area(SWEc)were recorded.?The temperatures of central area(Ta),temperatures of marginal area after ablation,and the temperatures of external normal area(Tc)were measured.Results1.At the 1h post ablation,the values measured by US(D1,D2,D3)were all smaller than the actual values(L1,L2,L3)in group 1,group 2 and group 3.The differences were statistically significant(D1<L1?D2<L2?D3<L3,P<0.05).2.At 1 h post ablation,SEL2 was smaller than L2 only in group 1,and the difference was statistically significant(P<0.05).3.The SEL 1 and SEL3 were more relevant to L1 and L3,respectively.4.Both SWEa and SWEb at each observation time post ablation were higher than those before ablation at each observation time in three groups,and there were statistical differences(P<0.01).The SWEa,SWEb and SWEc at the same observation time post ablation in each group declared,and the difference between two groups was statistically significant(P<0.01).5.The Ta,Tb and Tc at each measurement time post ablation in each group show a trend of decreasing gradient,and the differences were statistically significant(P<0.05).6.The SWEa,SWEb and SWEc measured immediately post ablation were significantly correlated with Ta,Tb and Tc(r=0.932,P<0.01),and a regression equation was obtained(T=0.318SWE+25.529).ConclusionAs compared to US,SE has a better evaluation on the ablation range.The SWE could be used to evaluate the effect of ablation by evaluating the hardness of ablation lesion.The same decreasing laws of SWE value and temperatures have a significant correlation,indicating the possibility of non-invasive temperature measurement using SWE.Part ? Preliminary exploration on the value of shear wave elastography in evaluating the effect of microwave ablation on hepatic malignant tumorObjectiveTo preliminarily explore the value of shear wave elastography(SWE)in evaluating the effect of microwave ablation on hepatic malignant tumor by comparing the hardness of hepatic malignant tumor measured by SWE before and after ablation.MethodsA total of 24patients(including 30lesions)with hepatic malignant tumor who received microwave ablation in Cancer Center of Guangzhou Medical University between April 2018 and January 2019 were included.The elastography was performed within 1 week before and after ablation.The SWE value of central area of lesion,SWE value of marginal area,and the SWE value of liver tissues surrounding the lesion were recorded.The mean of SWE was calculated.ResultsThe mean of SWE was 65.80±13.37 kPa for the central area of tumor and 39.93±7.87 kPa for the marginal area before ablation,both of which were greater than that for the perinatal liver parenchyma(13.36±2.29 kPa).The differences were statistically significant(P<0.05),The mean of SWE was 99.31±12.11 kPa for the central area and 68.40±7.93 kPa for the marginal area after ablation,both of which were greater than those before ablation.The differences were statistically significant(P<0.05).Through the ROC curve,it was indicated that the optimal diagnostic critical point of the mean of SWE for the marginal area of ablation lesion was 57.67 kPaDiscussionThe mean of SWE for the central area and marginal area of hepatic lesion after microwave ablation significantly increased.The ablation effect of hepatic tumor could be known simply and fast through the cutoff value(57.67 kPa)of the mean of SWE for the marginal area of ablation lesion obtained.