Role Of Elastography Combined Conventional Ultrasound In Axillary Examination Of Patients With Breast Cancer

Part Ⅰ Conventional ultrasound examination of axillary lymph nodes in patients with breast cancerObjective: To explore the diagnostic value of conventional ultrasound(US)for axillary lymph nodes(ALN)in patients with breast cancer.Methods: From December 2013 to July 2014,140 axillary lymph nodes with complete ultrasound images in 140 patients were included in our study.All of them underwent elastography.Six conventional US features of ALN were recorded: long axis diameter,short axis diameter,short-to-long axis diameter ratio(S/L ratio),cortical thickness,status of the hilum,and vascular pattern.The vascular pattern was defined as one of the following types:(1)absent or central pattern(predominant blood flow was detected within the hilum of the node);(2)peripheral pattern(multiple peripheral vessels were detected);and(3)mixed pattern(both central and peripheral disorderly blood flow was detected).Absence of blood or the central vascular pattern was defined as a normal feature,and the other vascular patterns were defined as abnormal features.Absence of hilum is defined as abnormal feature.The diagnostic performance of long axis diameter,short axis diameter,S/L ratio and cortical thickness were separately analyzed by statistical analysis.The best cut-off values for significant parameters were determined by ROC curves.Diagnostic performance of US was evaluated by combining all significant features.Results: Among the 140 lymph nodes,78 were confirmed to be metastatic,and 62 were confirmed to be nonmetastatic by the final pathologic diagnosis.There were significant differences between metastatic and nonmetastatic ALN in short axis diameter(P=0.000),S/L ratio(P=0.000),cortical thickness(P=0.000),status of hilum(P=0.000)and vascular pattern(P=0.000).However,there was no significant difference in long axis diameter between metastatic and nonmetastatic ALN(P=0.067).The sensitivity,specificity,accuracy,PPV and NPV were 76.9%,87.1%,81.4%,88.2% and 75.0% respectively.Conclusion: Conventional ultrasound was value in the differentiation of metastatic and nonmatestatic ALN.However,its sensitivity was not satisfying.Part Ⅱ Elastogtaphy of axillary lymph nodes in patients with breast cancerObjective: To explore the role of strain elastography(UE)in the differentiation of metastatic and nonmetastatic ALN in patients with breast cancer.Methods: We retrospectively analyzed the elastography images of 140 ALN.In our study,tissue stiffness increases with color from green togray to red,with red representing the highest stiffness on color elastography.Representative elastography image of each ALN was chosen from the short elastography video.All elastography images were evaluated by two experienced radiologists.The proportion of red areas(hard areas)in each lymph node was completely visually estimated by the radiologists and disagreements were solved by consensus.The elastography result was defined as positive if the proportion was 50% or greater.Otherwise,it was defined as negative.Pathologic results were considered as standard reference.Results: There were 78 metastatic ALN and 62 nonmetastatic ALN.Among the 78 metastatic ALN,approximately 60.3%(47/78)were positive on UE.Approximately 96.8%(60/62)of nonmetastatic ALN were negative on UE.The sensitivity,specificity,accuracy,PPV and NPV were 60.3%,97.8%,76.4%,95.9% and 65.9% respectively.Conclusion: The specificity and PPV of elastography were high in the differentiation of metastatic and nonmetastatic ALN while the sensitivity was very low.Part Ⅲ Elastography combined with conventional ultrasound in axilla examination of patients with breast cancerObjective: To explore the role of elastography combined with conventional ultrasound in axilla examination of patients with breast cancer.Methods: Two different combination methods using US and UE were analyzed in this study:(1)disjunctive combination,in which the lymph node was defined as a metastatic node when it was defined as positive on either conventional US imaging or elastography;and(2)conjunctive combination,in which the lymph node was identified as a metastatic node only when it was defined as positive on both conventional US imaging and elastography.Results: The sensitivity,specificity,accuracy,PPV and NPV of disjunctive combination method and conjunctive combination method were 84.6%,83.9%,84.3%,86.8%,81.3% and 52.6%,100%,73.6%,100%,62.6% respectively.Conclusion: Elastography could provide additional diagnostic information when combined with conventional ultrasound.Elastography can improve the sensitivity when disjunctively combined with US.False positive results could be avoided when adopting conjunctive combination method.