Interventionelle Onkologie in der Urologie

The Influence of Preablation Embolization Particle Size on the Size of the Microwave Ablation Zone in a Porcine Orthotopic Renal Tumor Model

PURPOSE

To determine the effect of arterial embolization using different embolic agents and sizes on microwave ablation (MWA) zone size in a porcine renal tumor (RT) model.

MATERIALS AND METHODS

In a transgenic porcine kidney, 32 sites were inoculated, with 28 orthotopic RTs induced. Experimental groups (23 tumors) underwent angiography with arterial embolization using various embolic materials (calibrated particles from 40 to 1,200 μm, and ethiodized oil) to achieve vascular stasis of the RT. MWA using a standard protocol (3 minutes at 65 W) was subsequently performed for all tumors. Gross and histologic ex vivo analyses of the ablation zones were performed.

RESULTS

Control group ablation zone volume without prior embolization was 5.24 cm3 (SD ± 0.55). Ablation zones after embolization with 40 μm, 100 μm, 300-500 μm, 900-1,200 μm particles were significantly larger than those with MWA alone (mean, 15.39 cm3 [SD ± 4.54]; P = .002; 11.07 cm3 [SD ± 1.39]; P = .001; 8.68 cm3 [SD ± 0.77]; P = .001; and 9.90 cm3 [SD ± 1.62]; P = .002, respectively). Liquid embolic ethiodized oil emulsion did not create a significant increase in the ablation zone (5.92 cm3 [SD ± 1.43 cm3]; P = .492).

CONCLUSIONS

Pre-MWA arterial embolization in a porcine RT model produced a statistically significant increase in the ablation zone when compared with MWA alone. Using smaller particle size embolic material with distal embolization at the tumor arterioles (50-150 μm) produced the largest, almost 3-fold increase in ablation zone volume.

Urinary tract effects after multifocal nonthermal irreversible electroporation of the kidney: acute and chronic monitoring by magnetic resonance imaging, intravenous urography and urinary cytology

PURPOSE

The nonthermal irreversible electroporation (NTIRE) is a novel potential ablation modality for renal masses. The aim of this study was the first evaluation of NTIRE's effects on the renal urine-collecting system using intravenous urography (IVU) and urinary cytology in addition to histology and magnetic resonance imaging (MRI).

METHODS

Eight percutaneous NTIRE ablations of the renal parenchyma, including the calyxes or pelvis, were performed in three male swine. MRI, IVU, histology, and urinary cytology follow-ups were performed within the first 28 days after treatment.

RESULTS

MRI and histological analysis demonstrated a localized necrosis 7 days and a localized scarification of the renal parenchyma with complete destruction 28 days after NTIRE. The urine-collecting system was preserved and showed urothelial regeneration. IVU and MRI showed an unaltered normal morphology of the renal calyxes, pelvis, and ureter. A new urinary cytology phenomenon featured a temporary degeneration by individual vacuolization of detached transitional epithelium cells within the first 3 days after NTIRE.

CONCLUSIONS

This first urographical, urine-cytological, and MRI evaluation after porcine kidney NTIRE shows multifocal parenchyma destruction while protecting the involved urine-collecting system with regenerated urothelial tissue. NTIRE could be used as a targeted ablation method of centrally located renal masses.