Correlation of Ablation Volume with Renal Function Loss after Cryoablation in Solitary Functioning Kidneys.

Purpose: To determine the degree of renal function deterioration after renal cryoablation in patients with a solitary functioning kidney on the basis of ablation volume.

Materials And Methods: Over a 15-year period, 81 percutaneous cryoablations were performed in solitary functioning kidneys. After exclusion of patients with baseline end-stage renal disease (ESRD) and insufficient follow-up, analysis was performed on 65 procedures in 52 patients (40 men; mean age, 63.5 years). The postcryoablation renal function was based on the lowest serum creatinine within 6 months after procedure. Renal function change was defined as percentage glomerular filtration rate (GFR) change. Volumetric analysis was performed on the target lesion, renal parenchyma, and ablation zone.

Results: The median tumor diameter was 2.0 cm (range, 0.8-4.7 cm). The median baseline GFR decreased from 56.4 mL/min/1.73 m (range, 17.5-89.7 mL/min/1.73 m) to 46.9 mL/min/1.73 m (range, 16.5-89.7 mL/min/1.73 m) at median of 95 days (P < .001), equating to a -7.9% median renal function change (range, -45.0% to +30.7%). All patients had Stage 2 or worse chronic kidney disease, and baseline function did not correlate with renal function change. The median volume of ablated parenchyma was 19.7 mL (range, 2.4-87.3 mL), equating to 8.1% (range, 0.7%-37.2%) of total parenchyma. The volume of parenchymal volume ablated correlated significantly with renal function loss, whereas age, hypertension, and diabetes mellitus did not. No patient developed ESRD within 1 year after cryoablation.

Conclusions: Cryoablation in solitary functioning kidneys resulted in a modest reduction in renal function, even in patients with chronic kidney disease and ablations of up to 20% of renal parenchymal volume.