Renal ablation by histotripsy--does it spare the collecting system?
OBJECTIVE
The feasibility of histotripsy (transcutaneous nonthermal mechanical tissue fractionation) was previously demonstrated in an in vivo rabbit renal cortex model. We explored the spectrum of histotripsy bio-effects on different tissue types in an in vitro porcine kidney model.


METHODS
Using an 18 element focused annular array ultrasound system we performed histotripsy treatments in 5 in vitro porcine kidneys, targeting 7 cortical volumes and 17 tissue volumes bridging the cortex, medulla and/or collecting system. Treated areas were observed using ultrasound. In 5 lesions methylene blue was infused into the collecting system to evaluate the preservation of collecting system integrity. Kidneys were sectioned and examined grossly for evidence of tissue fractionation, ie the presence of histotripsy paste, or fixed in formalin and prepared for histological analysis.


RESULTS
Histotripsy of renal cortical tissue created tissue defects in the cortical area treated. Histotripsy targeting the renal collecting system, medulla and renal cortex resulted in tissue fractionation in the area of the cortex, intermediate damage in the medulla and minimal damage to the collecting system.


CONCLUSIONS
There is a differential histotripsy treatment effect when comparing renal cortical tissue to renal collecting system. There is no significant architectural disruption of the renal collecting system after histotripsy. This differential effect is a notable finding that may prove useful in future planning of ablative treatments for renal tissue.
Lake
A M
AM
Department of Urology, University of Michigan, Ann Arbor, Michigan 48109, USA. alilake@med.umich.edu
Xu
Z
Z
Wilkinson
J E
JE
Cain
C A
CA
Roberts
W W
WW
D000818:Animals; D004195:Disease Models, Animal; D007672:Kidney Cortex / Q000000981:diagnostic imaging* / Q000473:pathology; D007679:Kidney Medulla / Q000000981:diagnostic imaging* / Q000473:pathology; D007685:Kidney Tubules, Collecting / Q000000981:diagnostic imaging* / Q000473:pathology; D013552:Swine; D014464:Ultrasonic Therapy; D014463:Ultrasonography