Clinical application of contrast-enhanced ultrasound after percutaneous renal tumor ablation

To evaluate the effectiveness of contrast-enhanced ultrasound (CEUS) in detecting incomplete ablation and local recurrence of renal tumors after percutaneous radiofrequency ablation (RFA).

31 patients were included for RFA treatment and underwent CEUS examination after RFA, ablation zone and contrast distribution in the ablation area were observed, CEUS images were compared with enhanced CT/MRI images to determine the residual tumors and local recurrence of renal tumors.

The average maximum diameters of the tumor and the ablation zone after the first RFA were 32.3 ± 14.7 mm and 35.9 ± 12.2 mm, respectively. A higher rate of complete tumor ablation was achieved if the ablation zone was larger than the primary tumor (p = 0.026). Within 1 month after RFA, contrast-enhanced CT/MRI examinations demonstrated incomplete ablation in 9 of 31 patients (29.0%), while CEUS revealed incomplete ablation in 8 of 31 patients (25.8%). The sensitivity, specificity, positive predictive value and negative predictive value of CEUS in evaluating complete ablation of renal tumors were 88.9%, 100%, 100%, 95.7%, respectively. During the follow-up period, local recurrence was reported in 2 (7.4%) of the 27 patients with complete tumor ablation. Tumor recurrence signs in the two patients were identified by both CEUS and contrast-enhanced CT/MRI. Therefore, both the sensitivity and specificity of CEUS for the evaluation of tumor recurrence were 100%.

After percutaneous RFA of renal tumors, the effectiveness of CEUS in the follow-up assessment of residual and recurrent tumors is basically the same as that of contrast-enhanced CT/MRI.

In this study, we evaluated the effectiveness of CEUS in the follow-up assessment of residual and recurrent tumors after RFA is basically the same as that of contrast-enhanced CT/MRI. Combining multiple follow-up methods may improve the detection rate of residual or recurrent tumors.