Degree of tumor enhancement should be considered when counseling patients prior to radiofrequency ablation (RFA) for malignant renal tumors.1

Investigators conducted a retrospective review of patient who underwent RFA for renal tumors and had contrast enhanced imaging performed. They calculated the change in Hounsfield units between the time from non-contrast phase to contrast-enhanced arterial phase in order to determine if greater tumor enhancement was a risk factor for RFA failure due to increased vascularity.

A total of 99 patients with biopsy confirmed malignant renal tumors and contrast-enhance imaging were included in the study. Results showed that the incomplete ablation rate was significantly less for tumors that enhanced < 60 HU vs ≥ 60 HU. Multivariate logistic regression analysis confirmed those results (OR, 1.14; P = .008).

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Patients whose tumors were smaller than 3 cm had better 5-year disease-free survival (100% vs 69.2%, respectively; P < .01). Five-year disease-free survival for patients whose tumors had HU changes < 60 was 100% compared with 92.4% for patients who had an HU chance ≥ 60.

“Biopsy confirmed malignant renal tumors, which exhibit a change in enhancement ≥ 60 HU, experience a higher rate of incomplete initial tumor ablation than tumors < 60 HU,” the authors concluded.


  1. Lay AH, Stewart J, Canvasser NE, et al. Likelihood of incomplete kidney tumor ablation with radiofrequency energy: degree of enhancement matters [article in press]. J Urol. doi: 10.1016/j.juro.2016.01.099.