The Diagnostic Value Of Ultrasonic Elastography In Cervical Lymphadenopathy

Objective1.To compare the value of Utrasonic Elastography(UE), B-mode ultrasonic sonography (B-US) and Power Doppler Imaging (PDI) in the differential diagnosis of cervical lymphadenopathies, and analyze their advantages and limitations.2. To get the relative stiffness by measuring the strain ratio of lymph nodes to the surrounding tissue in the same level. The ROC (Receiver Operator Characteristic) curve was made by the probability of malignancy according to the strain ratio. The area under the ROC curve(Az)was the judgement index used to test the clinical diagnosis value of the strain ratio. A strain ratio cutoff point enabled the best distinction between benign and malignant lymphnodes, providing a new and important detection criterion for the diagnosis of benign and malignant lymphadenopathies.Materials and MethodsFrom August to December 2009,107 patients with 128 suspected cervical lymphadenopathies were examined with B-US, PDI and UE. The objective lymphnodes were dissected and confirmed by surgical pathology. HITACHI HV-900 ultrasound system with the technology of ultrasonic elastography was used in this study. All objective lymphnodes were performed three ultrasonic modalities before surgery. The grading of the blood flow referred to five levels (Wu et al), and the elastogram were analyzed according to the four-score(Furukawa), which was collected before the histopathology conformed. The three observers were independently asked to assess the sonographic features and to decide whether a particular node was benign or malignant.ResultsWith pathologic diagnosis as the golden standard, ROC curves were obtained to assess the performance of the strain ratio.1.5 was the best cutoff point of the strain ratio for differentiating malignant from benign lymphadenopathies. Its senstivity, specificity, accuracy, positive predictive value and negative predictive value were 92.8%,53.4%, 75%,70.7% and 86.1% respectively. The specificity, sensitivity, accuracy, positive predictive value and negative predictive value of elastography scores were 50%,87.9%,67.2%,85.3% and 59.3%. However, combined the strain ratio and UE scores, the specificity, sensitivity, accuracy, positive predictive value and negative predictive value were 95.7%,55.1%,77.3%,72%,91.4%. As to all evaluating indicators(except positive predicative value), UE and PDI were significant higher than B-US compared by the McNemar x2 test(P<0.001). With regard to sensitivity and negative predictive value, no significant differences were found between UE and PDI(P>0.05). Interobservers agreement was the highest in three modalities when we used UE scoring method alone. ConclusionThe strain ratio of lymphanodes to the same level soft tissue can quantitaively evaluate the stiffness of lymphadenopathies, which is more objective than the UE scoring method. The strain ratio can be used as a new supplementary measure for differentiation of benign and malignant lymphadenopathies.1.5 was the best cutoff point of the strain ratio for differentiating malignant and benign cervical lymphadenopathies. UE is useful in differential lymphadenopathies.