Atwell TD et al. (2007) Percutaneous cryoablation of 40 solid renal tumors with US guidance and CT monitoring: initial experience. Radiology 243: 276–283

Percutaneous radiofrequency ablation, although a promising therapy for small, solid renal tumors, is less suitable for large tumors or masses adjacent to critical structures, such as the bowel, and the ablation cannot be monitored by CT imaging. Atwell et al. retrospectively investigated the use of percutaneous ultrasonographically guided cryoablation using CT monitoring, which allows visualization of the lethal ice ball.

Forty individuals were included, each with one renal tumor (mean diameter 3.4 ± 1.3 cm; 20 [50%] ≥3 cm), 19 (48%) of which extended into the renal sinus fat. Cryoablation was performed under general anesthesia. Each patient received one freeze-thaw-refreeze treatment cycle (mean duration of each freeze = 11 min) with monitoring of the ice ball using CT. Contrast-enhanced CT (or MRI if CT was contraindicated) was scheduled during, within 48 h, and at 3–6, 12, 18, 24 and 36 months after ablation. Extension of the ice ball 5 mm beyond the tumor margin during freezing and no contrast enhancement on imaging immediately after the procedure was deemed a successful treatment.

Cryoablation was successful in 38 (95%) patients, 29 (76%) of whom were followed for a mean duration of 8.0 ± 4.4 months. A 100% tumor control rate was achieved, with no local recurrences being identified. Two perinephric hemorrhages and one case of hypertension were reported, but only one adverse event was serious.

The authors conclude that cryoablation is safe and efficacious for small and large solid renal tumors in critical locations.