Histotripsy of the Proximal Ureter and Renal Pelvis: Evaluation of Urothelial Injury in a Porcine Survival Model.

PURPOSE

To evaluate the response of the ureter and renal pelvis to direct targeting by histotripsy guided by cone-beam computed tomography (CT) in a human-scale porcine chronic-survival model.

MATERIALS AND METHODS

Bilateral ureteral histotripsy treatments were completed on 6 female swine (n = 12). Animals were divided into 2 groups: (a) acute (n = 2 animals, 4 treatments, sacrificed at Day 0) and (b) chronic (n = 4 animals, 8 treatments, sacrificed at Day 7 [n = 2] and Day 28 [n = 2]). For each treatment, a 2.5-cm sphere (ureter/renal pelvis and renal parenchyma) was targeted using cone-beam CT guidance. CT urography imaging was performed immediately after treatment for all animals, and on Days 7 and 28 for chronic animals, followed by sacrifice, necropsy, and histopathology. Serum chemistries were drawn before treatment and at Days 7 and 28.

RESULTS

All 12 treatments were successful in targeting the renal pelvis/ureter and renal parenchyma. CT urography findings at Day 0 included ureteral thickening (9/12), delayed parenchymal enhancement (3/12), and mild hydronephrosis (5/12), all resolving by Day 7. Histologic findings of low-grade damage resolved by Day 7. No urine leaks or ureteral strictures were observed. Renal function (creatinine and estimated glomerular filtration rate) remained within the normal range throughout the study.

CONCLUSIONS

Histotripsy treatment of the ureter and renal pelvis results in transient injuries, suggesting that treatment of central renal tumors adjacent to the ureter and renal pelvis is safe. The results of this study could help expand the range of renal tumors that can be treated with histotripsy.