Objective: To evaluate the diagnostic accuracy of contrast-enhanced ultrasound (CEUS) in the early detection of residual tumour after radiofrequency ablation (RFA) of renal tumours.
Methods: Patients referred to our institution for RFA of renal tumours prospectively underwent CEUS and computed tomography (CT) or magnetic resonance imaging (MRI) before, within 1 day and 6 weeks after treatment. Identification of residual tumour was assessed by three blinded radiologists. Reference standard was CT/MRI performed at least 1 year after RFA.
Results: A total of 66 renal tumours in 43 patients (median age 62 years; range 44-71.5) were studied. Inter-reader agreement (kappa value) was 0.84 for CEUS. Prevalence of residual disease was 19%. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV), respectively, were as follows: 64% [confidence interval (CI) 39-84], 98% [CI 91-100], 82% [CI 52-95] and 92% [CI 83-97] on 24-h CEUS; 79% [CI 52-92], 100% [CI 94-100], 100% [CI 74-100] and 95% [CI 87-100] on 6-week CEUS; 79% [CI 52-92], 95% [CI 86-98], 79% [CI 52-92] and 95% [CI 86-98] on 24-h CT/MRI; and 100% [CI 72-100], 98% [CI 90-100], 91% [CI 62-98] and 100% [CI 93-100] on 6-week CT/MRI.
Conclusion: CEUS has high specificity for the early diagnosis of residual tumour after renal RFA.