Abstract
PURPOSE: Contrast-enhanced ultrasound (CEUS) is a new technique used to distinguish benign from metastatic superficial lymph nodes (LNs) with variable accuracy. The objective of this meta-analysis was to evaluate the accuracy of CEUS for the diagnosis of superficial metastatic LNs. METHODS: A comprehensive literature search of PubMed, Web of Science, Medline, Embase, and the Cochrane Library was performed until April 2018. Nine articles reporting the diagnosis of 436 LNs by CEUS were investigated. The Mantel-Haenszel and DerSimonian-Laird methods were used to analyze pooled sensitivity, specificity, diagnostic OR, positive likelihood ratio (LR), and negative LR, and a summary receiver operating characteristic (SROC) curve was also evaluated. RESULTS: The pooled sensitivity and specificity of CEUS for the differential diagnosis of benign and metastatic superficial LNs were 0.88 (95% CI, 0.83-0.92) and 0.80 (95% CI, 0.74-0.85), respectively. The pooled positive LR, negative LR, and diagnostic OR were 4.36 (95% CI, 2.38-7.99), 0.17 (95% CI, 0.10-0.31), and 32.75 (95% CI, 11.08-96.84), respectively. SROC area under the curve (AUC) was 0.9288. The subgroup analysis excluding outliers implied that the heterogeneity was almost eliminated, and the pooled sensitivity and specificity were 0.87 (95% CI, 0.81-0.92) and 0.79 (95% CI, 0.71-0.85), respectively. The SROC AUC was 0.8950. CONCLUSION: CEUS, a novel imaging modality for the characterization of superficial LNs, shows a high sensitivity and specificity in the diagnosis of superficial metastatic LNs. The different diagnostic standards, contrast agents, and contrast modes contribute to a considerable level of heterogeneity among studies. A uniform standard for distinguishing between benign and metastatic LNs is needed for further clinical application.