OBJECTIVE To evaluate efficacy of using 2D and 3D contrast enhanced ultrasound (CEUS) for surveillance of RCC recurrence in patients post-ablation and identify imaging hallmarks of recurrence. METHODS 53 patients >8 months post ablation of RCC provided informed consent for this IRB approved study. Patients received 2D and 3D CEUS examinations with Optison (GE Healthcare). Three radiologists of varying CEUS experience described enhancement characteristics, made a diagnosis of recurrence/no-recurrence, and quantified their diagnostic confidence levels. RESULTS Cases of RCC recurrence showed full ablation cavity enhancement with equal arrival times and intensity compared to the renal cortex. Lack of recurrence was characterized as a complete lack of enhancement within the cavity, or delayed enhancement stemming from the periphery of the ablation cavity. Sensitivity for detecting RCC recurrence was 100% for all readers and specificity was 90%-94%. Reader agreement ranged from 88% to 96%. No significant improvements were achieved with the addition of 3D CEUS, and its inclusion resulted in decreased reader confidence. CONCLUSION Contrast-enhanced ultrasound successfully identified all cases of RCC recurrence in this study. Importantly, some patients with complete response to treatment developed delayed enhancement at the periphery of the ablation cavity over time, corresponding to fat necrosis, scarring or granulation tissue within the ablation cavity. (C) 2018 Elsevier Inc.