Diagnostic performance of contrast-enhanced ultrasound in the evaluation of small renal masses: a systematic review and meta-analysis

Ultrasound (US) is a highly sensitive imaging tool in the detection of renal masses. However, the detection rate of small renal masses (SRMs) (<4 cm) is still limited. In this scenario, contrast-enhanced ultrasound (CEUS) is a relatively novel, but increasingly utilized, diagnostic modality which aims to increase the overall diagnostic ability in the identification of SRMs. In consequence, we performed a systematic review (SR) and pooled meta-analysis to investigate the diagnostic performance of CEUS in the evaluation of SRMs confirmed by pathology. A SR up to April 2022 was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. The diagnostic performance of CEUS was evaluated basing on malignant vs. benign SMRs. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) from eligible studies were pooled, and summary receiver operating characteristic (SROC) curves were constructed for each endpoint. Overall, five qualified studies were deemed suitable for this meta-analysis. Finally, diagnostic performance of CEUS showed an accuracy of 0.93 in detecting malignant masses (sensitivity of 0.94, PPV of 0.95, specificity of 0.78, and NPV of 0.73). Taken together, CEUS may represent a promising minimally invasive diagnostic tool for characterization of SMRs, since it allows clinicians to identify malignant lesions.