Canine prostate: contrast-enhanced US-guided radiofrequency ablation with urethral and neurovascular cooling--initial experience.
OBJECTIVE
To prospectively evaluate in a canine model contrast material-enhanced ultrasonography (US) for guiding and monitoring radiofrequency (RF) ablation of the entire prostate, with urethral and vascular cooling to protect the surrounding structures.


METHODS
After approval by the institutional animal use and care committee, an RF electrode was used to ablate the entire prostate in 15 dogs. During ablation, pulse-inversion harmonic US was performed by using an endocavitary probe after an intravenous bolus injection (0.04 mL/kg) and infusion (0.015 muL/kg/min) of a US contrast agent. In group 1 (n = 4), no cooling protection was used during ablation. In group 2 (n = 5), urethral and bladder protection was provided by inserting a 12-F catheter infused with cold saline (8 degrees C +/- 4 [standard deviation]) at a rate of 100 mL/min. In group 3 (n = 6), further protection of the neurovascular bundles (NVBs) was provided by infusing cold saline (8 degrees C +/- 4) into the iliac arteries at a rate of 50 mL/min by means of catheterization of the femoral artery. Pathologic findings among the three groups were compared by using the Wilcoxon rank sum test.


RESULTS
The average volumes of prostate ablation achieved in the three groups were 96.6%, 91.9%, and 92%. Contrast-enhanced pulse-inversion harmonic US allowed visualization and monitoring of urethral and NVB blood flow during the ablation. Without protection, damage to the urethra and the NVB was demonstrated at both US and pathologic examination. There was highly significant difference in urethral damage between groups with and the group without urethral cooling (P = .002), while intraarterial cooling demonstrated a nonsignificant trend toward a decreased NVB damage (P = .069).


CONCLUSIONS
Contrast-enhanced US can guide RF ablation of the entire prostate. Infusion of cold saline provides effective protection for the urethra during such procedures. The application of intraarterial cooling did not provide a significant improvement in the protection of the NVB in this small study.
Liu
Ji-Bin
JB
Department of Radiology, Thomas Jefferson University, 7th Floor Main Building, 132 S 10th St, Philadelphia, PA 19107, USA. ji-bin.liu@jefferson.edu
Wansaicheong
Gervais
G
Merton
Daniel A
DA
Chiou
See-Ying
SY
Sun
Yao
Y
Li
Kai
K
Forsberg
Flemming
F
Edmonds
Pamela R
PR
Needleman
Laurence
L
Halpern
Ethan J
EJ
D000818:Animals; D017115:Catheter Ablation; D003080:Cold Temperature; D003287:Contrast Media / Q000008:administration & dosage; D004285:Dogs; D005290:Ferric Compounds / Q000008:administration & dosage; D007501:Iron / Q000008:administration & dosage; D008297:Male; D023421:Models, Animal; D010087:Oxides / Q000008:administration & dosage; D011446:Prospective Studies; D011467:Prostate / Q000000981:diagnostic imaging / Q000601:surgery*; D012007:Rectum; D012462:Saline Solution, Hypertonic / Q000008:administration & dosage; D018709:Statistics, Nonparametric; D018084:Ultrasonography, Interventional; D014521:Urethra / Q000293:injuries
D003287:Contrast Media; D005290:Ferric Compounds; D010087:Oxides; D012462:Saline Solution, Hypertonic; C069727:Sonazoid; D007501:Iron