Small renal mass cryosurgery: Imaging and vascular changes

The combined use of a fluorescent casting technique, cryomicrotome imaging, and 3-D computer analysis as a new static method for visualizing and reconstructing the vascular anatomy in a porcine renal model was studied. The arterial blood supply in 3-D at a resolution of up to 50μm of the whole could be visualized. This method could be used to visualize the process following parenchymal cryoablation injury and establish a microvascular diameter threshold of 180μm for acute vascular damage. However, the branching structures of larger arteries remained anatomically intact. In an in vivo study we quantified temporary vascular changes after cryosurgery. Some anatomically arterial vessels were still present after 2 days but after one week the vascular structures in the ablation crater had disappeared completely.
We investigated the impact of the RENAL and PADUA nephrometry indices on the assessment of intraoperative (IOC) and postoperative complications in patients with primary renal tumors treated with laparoscopic cryoablation (LCA). The domains "diameter" of both indices were significantly correlated with the risk for IOC. The threshold tumor diameter of 35mm was found to be predictive for an increased risk for IOC performing LCA.
The observation that the standard follow-up, using contrast-enhanced computed tomography, in patients treated with cryoablation for a small renal mass runs the risk of jeopardizing the renal function led to the study of alternative imaging methods. The studies show that Contrast Enhanced UltraSonography can be used to describe the perfusion characteristics and 18F-FDG PET-CT could be used to discriminate for metabolic activity of cryoablation lesions.