Contrast-enhanced ultrasonography for the diagnosis of small hepatocellular carcinoma: a meta-analysis and meta-regression analysis.

The aim of this study is to determine the diagnostic accuracy of contrast-enhanced ultrasonography (CEUS) for diagnosis of small (≤ 2 cm in diameter) hepatocellular carcinoma (HCC) through a meta-analysis of published studies. A comprehensive literature search of PubMed, Embase, Web of Science, and China BioMedicine databases was conducted on articles published before 1 March 2013. Data from selected studies were pooled to yield summary sensitivity, specificity, positive and negative likelihood ratio (LR), diagnostic odds ratio (DOR), and receiver operating characteristic (SROC) curve. Statistical analyses were performed using Meta-Disc version 1.4 and STATA version 12.0 softwares. Fifteen studies were included with a total of 908 cirrhotic patients with 1,032 small hepatic nodules. All lesions were histologically confirmed through liver biopsies after CEUS. The pooled sensitivity was 0.81 (95% CI = 0.78-0.85); the pooled specificity was 0.86 (95% CI = 0.82-0.89). The pooled positive LR was 5.90 (95% CI = 3.90-8.94); the pooled negative LR was 0.20 (95% CI = 0.14-0.29). The pooled DOR was 37.07 (95% CI = 24.79-55.44). The area under the SROC curve was 0.93 (SE = 0.01). Meta-regression analysis showed that the number of lesions may be a major source of heterogeneity. No publication bias was detected in this meta-analysis. This meta-analysis indicates that CEUS is a useful diagnostic tool with high sensitivity and specificity for identifying small HCC.