Ex Vivo Porcine Model for Ureteral Stent Placement Training.

Realistic simulation models for interventional radiology procedures are limited, including for placement of double-J ureteral stents (DJSs). Using a porcine kidney and empty saline bag (bladder), an ex vivo model aiming to improve operators' knowledge and confidence in performing a DJS procedure was developed. Six faculty (J.W., J.L.) and 14 trainees (C.B.O.) successfully operated on the model. Mean results for faculty versus trainees were as follows: 2.2 (SD ± 1.5) versus 2.4 (SD ± 1.5) puncture attempts to access the collecting system (P = .78), 14.5 minutes (SD ± 4.8) versus 15.1 minutes (SD ± 6.0) for insertion time (P = .84), 7.3 minutes (SD ± 2.8) versus 10.3 minutes (SD ± 2.6) for exchange time (P = .04), 8.48 minutes (SD ± 2.0) versus 8.01 minutes (SD ± 2.6) for fluoroscopy time (P = .70), and 5.7 mGy (SD ± 1.6) versus 5.4 mGy (SD ± 2.0) for absorbed air kerma (P = .77). Self-assessed knowledge and confidence with DJS placement increased for all participants following model use.

Changes in Microwave Ablation Zone Dimensions after Transarterial Embolization in an Ex Vivo Human Kidney Perfusion Model.

PURPOSE: To utilize a novel ex vivo perfused human renal model and quantify microwave ablation (MWA) size differences in renal tissue when combining MWA with transarterial embolization (TAE). MATERIALS AND METHODS: Human kidneys (n = 5) declined for transplantation were obtained and connected to a fluoroscopy-compatible ex vivo perfusion system. Two ablations-1 standard MWA and 1 TAE-MWA-were performed in each kidney for 2 minutes at 100 W using a MWA system (Solero Angiodynamics). MWA alone was performed in the upper pole. In the lower pole, MWA was performed after TAE with 40-90 µm radiopaque microspheres to achieve angiographic stasis. Ablation zones of coagulative necrosis were sectioned along the long axis and segmented for maximal short-axis diameter (SAD) and long-axis diameter (LAD) measurements. RESULTS: A total of 10 ablations (5 MWAs and 5 TAE-MWAs) were performed in 5 human kidneys. TAE-MWA resulted in significantly increased SAD, LAD, volume, and sphericity compared with standard MWA ± SD, with mean measurements as follows (5 standard MWAs ± SD vs 5 TAE-MWAs ± SD, 2-tailed t-test): (a) SAD, 1.8 cm (SD ± 0.1) versus 2.5 cm (SD ± 0.1) (P < .001); (b) LAD, 2.9 cm (SD ± 0.3) versus 3.2 cm (SD ± 0.1) (P = .039); (c) volume, 5.0 mL (SD ± 0.5) versus 11.0 mL (SD ± 0.7) (P < .001); and (d) sphericity, 0.4 (SD ± 0.2) versus 0.6 (SD ± 0.1) (P = .049). Histology demonstrated no differences in TAE-MWA other than concentrated microspheres. CONCLUSIONS: This ex vivo human kidney perfusion model confirmed that combined MWA-TAE significantly increased ablation size and spherical shape compared with MWA alone.

Creation of an Ex Vivo Renal Perfusion Model to Investigate Microwave Ablation.

This study hypothesized that an ex vivo renal perfusion model can create smaller microwave ablation (MWA) measurements during perfused states compared with nonperfused states across multiple device settings. Nine bovine kidneys, a fluoroscopic compatible perfusion model, and a commercially-available clinical MWA system were used to perform 72 ablations (36 perfused and 36 nonperfused) at 9 different device settings. Comparing perfused and nonperfused ablations at each device setting, significant differences in volume existed for 6 of 9 settings (P < .05). Collapsed across time settings, the ablation volumes by power were the following (perfused and nonperfused, P value): 60 W, 2.3 cm3 ± 1.0 and 7.2 cm3 ± 2.7, P < .001; 100 W, 5.4 cm3 ± 2.1 and 11.5 cm3 ± 5.6, P < .01; and 140 W, 11.2 cm3 ± 3.7 and 18.7 cm3 ± 6.3, P < .01. Applied power correlated with ablation volume: perfused, 0.021 cm3/W and R = 0.462, P = .004, and nonperfused, 0.029 cm3/W and R = 0.565, P < .001. These results support that an ex vivo perfused organ system can evaluate MWA systems and demonstrate heat sink perfusion effects of decreased ablation size.