Negative Predictive Value of Contrast‐Enhanced Ultrasound in Differentiating Avascular Solid‐Appearing From Vascularized Masses: A Retrospective Consecutive Study

Abstract

OBJECTIVES: To determine the negative predictive value (NPV) of contrast-enhanced ultrasound (CEUS) to establish the lack of vascularity in a mass. METHODS: This work was an Institutional Review Board-approved, Health Insurance Portability and Accountability Act-compliant retrospective study. Acquisition of consent was waived. We included all CEUS examinations performed for tissue characterization between 2004 and 2014 that reported showing no vascularity in a mass. Contrast-enhanced ultrasound findings were considered true-negative when there was stability on imaging for at least 1 year or no evidence of a solid mass, if biopsied, and false-negative if there was lesion growth on imaging within 12 months or an indication of a solid mass on the pathologic examination, if biopsied. One author reviewed all of the reports and follow-up examinations. We conducted a consensus review of all false-negative findings mixed with an equal number of true-negative findings by 2 reviewers, who were blinded to the final results. RESULTS: The study population consisted of 97 CEUS examinations in 97 patients, including 48 women and 49 men (mean age ± SD, 65 ± 14 years). Examinations were performed for lesion characterization in the liver (n = 23), pancreas (n = 17), kidney (n = 54), 1 gallbladder, 1 adnexa, and 1 peritoneal lesion. The overall false-negative rate on the official prospective review was 2% (2 of 97). Two false-negative findings were correctly identified on the consensus review. The NPV of CEUS was 97.9% (95 of 97; 95% confidence interval, 93%- 99%) on the official review. CONCLUSIONS: Contrast-enhanced ultrasound has a very high NPV to exclude the presence of flow in a mass, and it can be used to exclude the presence of a solid mass.