Feasibility of Contrast-Enhanced Ultrasound Fusion With Pretreatment MR/CT for Recurrence Detection in Renal Cell Carcinoma Patients During Post-Ablation Surveillance.

Objective: Contrast enhanced ultrasound (CEUS) is a cost-effective, safe, and accurate modality for monitoring renal cell carcinoma (RCC) recurrence following percutaneous ablation. However, ultrasound delineation of treated tumor borders can be challenging post-ablation. Here, we demonstrate the feasibility of using post-treatment CEUS fused to preablation MR/CT to detect RCC recurrence during long term follow up.

Methods: This study was performed as part of a larger ongoing prospective clinical trial for patients with biopsy-proven RCC treated with percutaneous ablation and receiving contrast enhanced (CE) -CT or -MRI for treatment response monitoring. CEUS with preablation CT/MR fusion was performed within 4 weeks of recurrence screening, and CE-CT/MRI was used as the reference standard. After intravenous injection of an ultrasound contrast agent, CEUS imaging of a single target lesion was performed with ultrasound fused to the patient's pretreatment CT or MRI. RCC recurrence was diagnosed at the bedside based on the presence of iso- to hyper-enhancement within the margins of the ablation cavity compared to normal renal parenchyma.

Results: To date, 50 participants have been recruited (76% male and 24% female). All participants tolerated the contrast injections without adverse events. CEUS was successfully fused to the participant's pretreatment cross-sectional imaging in all cases and was found to aid in the delineation of the original treatment zone. Additionally, CEUS correlated perfectly (100% agreement) with CE-CT/MRI findings for all the participants.

Conclusion: Preliminary results demonstrate that post-treatment CEUS fused with a pretreatment CT/MRI is feasible and may aid in the correct localization of the treated tumor margins during long-term post-ablation monitoring.