Pleural Ultrasound Elastography: A Novel Technique for the Differential Diagnosis of Malignant Pleural Effusion

Introduction: Traditional thoracic ultrasound (TUS) is often the initial tool used to help diagnose malignant pleural effusion (MPE). Ultrasound elastography (UE), a new technique, has been used to differentiate malignant disease from benign disease by evaluating tissue hardness. However, no studies evaluating the efficacy of UE in diagnosing MPE are available. We assessed the diagnostic value of UE for diagnosing MPE prospectively. Methods: All 244 enrolled patients were divided into a development set and a validation set in chronological order. TUS and UE were performed to diagnose MPE. The cut-off elasticity values (the mean and maximal values) were established using a receiver operating characteristic (ROC) curve constructed from continuous data of the patients in the development set. The diagnostic performance of UE was compared with that of TUS in the validation set. Results: In development set, the mean elasticity value (47·25 kPa) was the optimal cut-off. In the validation set, pleural UE had a sensitivity of 83·64%, a specificity of 90·67%, a positive predictive value (PPV) of 86·79%, and a negative predictive value (NPV) of 88·31% for distinguishing MPE from benign pleural effusion. The sensitivity of UE was significantly higher (p=0·006) than that of TUS (sensitivity of 60·00%, specificity of 93·33%, PPV of 86·84%, and NPV of 76·09%). Pleural UE detected 91·11% (41/45) of MPE cases from among false-negative cases as determined by TUS in all patients. Conclusion: Pleural UE is a good technique compared with TUS for differentiating MPE from benign pleural disease, especially in high tuberculosis burden countries. Funding Statement: The authors state: No funding source was involved. Declaration of Interests: The authors declare no conflicts of interest. Ethics Approval Statement: This study was approved by the Institutional Ethical Review Board of the First Hospital of China Medical University, and written informed consent was obtained from all patients.