Real-time Contrast-enhanced Ultrasonography In The Evaluation Of Microwave Ablation Therapy For Hepatic Malignancies

Real-time Contrast-enhanced Ultrasonography in the Evaluation of Microwave Ablation Therapy for Hepatic MalignanciesWith the development of medical imaging techniques,it is possible to diagnose and treat hepatic malignancy in an early stage.Local ablative therapy plays an important role in the management of hepatic malignancies.Ultrasound-guided percutaneous microwave ablation treatment for hepatic tumors is one of the minimal invasive techniques.The safety and effectiveness with low cost make it increasingly acceptable in our country.Since the percutaneous local ablation is usually performed under ultrasound guidance,assessment of the therapeutic response for hepatic cancers with ultrasonography seems preferable.So far,contrast-enhanced computed tomography(CT) or magnetic resonance imaging(MRI) is commonly used for the evaluation of nonsurgical treatment response for hepatic tumors.With the development of ultrasound contrast agent and imaging techniques,which overcome the limitation of conventional gray-scale ultrasonography and color Doppler ultrasonography in the detection and characterization of focal liver lesions, contrast-enhanced ultrasonography(CEUS) is reported to be widely used in the diagnosis and assessment of non-surgical treatments for hepatic tumors.In this study, we investigated the ability of a new generation contrast agent(SonoVue) with low mechanical index harmonic imaging techniques in the evaluation of microwave ablation treatment for hepatic malignancies.Chapter One Role of Contrast-enhanced Uitrasonography in the Characterization of Focal Liver Lesions before Microwave Ablation TherapyObjective To assess the value of CEUS in the differential diagnosis of focal liver lesions before microwave ablation.Methods From February 2002 to June 2008,one hundred and seven patients with 128 focal liver lesions underwent CEUS and color Doppler flow imaging(CDFI) before microwave ablation therapy.The ability of differential diagnosis of liver tumors with CEUS and CDFI was compared.Results In the diagnosis of hepatic malignancies,the sensitivity,specificity,positive predictive value,negative predictive value and diagnostic accuracy for malignancy by CDFI were 72.0%(87/121),42.9%(3/7),95.6%(87/91),8.1%(3/37),and 70.3%(90/128), respectively,and by CEUS were 98.3%(119/121),100%(7/7),100%(119/119), 77.7%(7/9),and 98.5%(126/128),respectively(P＜0.001).Conclusion CEUS is superior to CDFI in the characterization of focal liver tumors.Chapter Two Application of CEUS in the Selection of Indications of Hepatic Malignancies treated with Microwave AblationObjective To evaluate the clinical value of CEUS in making treatment protocols for hepatic malignancies before microwave ablation.Methods One hundred and sixteen patients with 130 hepatic malignancies before treatment underwent conventional gray-scale ultrasonography and CEUS examination.Results There were 51 lesions (39.2%,51/130) shown larger size on CEUS than that on conventional gray-scale ultrasonography.Besides 130 lesions on conventional ultrasonoghrphy,additional nine lesions missed on gray-scale conventional ultrasonography were detected by CEUS.Feeding vessels were detected in 33 lesions(25.3%,33/130) with CEUS. According to the indications of hepatic malignancies for microwave ablation,104 patients with 123 lesions received microwave ablation therapy totally and 12 patients were excluded based on the results of CEUS.Conclusion CEUS provides more important information on the characters,size,number and feeding vessels of hepatic malignancies before microwave ablation.It helps choosing proper indications and designing the treatment protocols.Chapter Three Preliminary Study of CEUS in the Evaluation of Treatment Response Immediately after Microwave Ablation for Hepatic MalignanciesObjective To evaluate the usefulness of immediate postprocedural CEUS in assessing the therapeutic response of microwave ablation for hepatic tomors.Methods Thirty-three patients with 38 focal liver lesions underwent CEUS assessment at thirty minutes to one hour after microwave ablation therapy.The results of immediate postprocedural CEUS were compared with those of follow up CEUS, contrast-enhanced CT and MRI at one month after microwave ablation therapy. Results Compared with the follow up contrast-enhanced CT or MRI,the sensitivity, specificity,positive predictive value,negative predictive value and diagnostic accuracy of immediate postprocedural CEUS were 66.7%(2/3),94.3%(33/35), 50%(2/4),97.1%(33/34) and 92.1%(35/38),respectively.There was no statistically significant difference between immediate postprocedural CEUS and contrast-enhanced CT or MRI(P=1.00).Conclusion Immediate postprocedural CEUS has a well concordance with follow up contrast-enhanced CT or MRI and follow up CEUS in the detection of residual tumor at one month after microwave ablation. However,it has some technical limitations.False-positive and false-negative results occurred in this study.The clinical value of immediate postprocedural CEUS in assessing the success of microwave ablation need to be further investigated.Chapter Four Value of Gray-scale Ultrasonograpy in the Prediction of Ablation Area during Microwave Ablation Therapy for Hepatic MalignanciesObjective To investigate the value of gray-scale ultrasonography in predicting the area of ablation during microwave ablation therapy of hepatic malignancies.Methods The spread of microbubbles during microwave ablation was observed by gray-scale ultrasonography in 41 patients with 41 hepatic malignancies and the largest transverse-diameter of the lesions were compared with those of the defect of enhancement in CEUS.Results The transverse-diameter(34.0±5.48mm) of the area of hyperechogenicity after ablation observed by gray-scale ultrasonography was correlated with that(25.5±10.59mm) of the defect enhancement observed by CEUS(r =0.54,P＜0.001).Conclusion The size of the area of hyperechogenicity after ablation observed by gray-scale ultrasonography was correlated well with that of the defect observed by CEUS.It is helpful in guiding the microwave ablation of hepatic malignancied by observing microbubbles area during the procedure.Chapter Five Role of CEUS in the Evaluation of Treatment Response after Microwave Ablation of Hepatic Malignancies Objective To evaluate the usefulness of CEUS in assessing the therapeutic response of microwave ablation in patients with hepatic malignancies.Methods A total of 101 focal liver lesions underwent CEUS one month after microwave ablation therapy.The results of CEUS were compared with those of contrast-enhanced CT or MRI.Results After microwave ablation,CEUS detected residual tumor enhancement in 8 lesions(7.9%,8/101) and showed no intratumoral enhancement in the remaining 93 lesions(92.1%,93/101).Compared with contrast-enhanced CT or MRI,the sensitivity, specificity,positive predictive value,negative predictive value and diagnostic accuracy of CEUS were 98.9%(91/92),7.8%(7/9),97.8%(91/93),87.5%(7/8) and 97.0%(98/101),respectively.Conclusion CEUS is comparable to contrast-enhanced CT or MRI in assessing the therapeutic effect of microwave ablation in hepatic malignancies,and it can be used in clinical setting.