Contrast-enhanced ultrasound evaluation of radiofrequency ablation of the kidney: reliable imaging of the thermolesion.
OBJECTIVE
Radiofrequency ablation (RFA) is limited by the inability to monitor progression of the thermal lesion. Contrast-enhanced ultrasonography (CEUS) imaging has considerable potential as a monitoring modality for RFA. We report our experience using CEUS to evaluate the lesion produced by RFA in a porcine model.


METHODS
Five pigs underwent laparoscopic RFA twice, spaced by a 1-week interval. Post- RFA ultrasound imaging was performed transcutaneously immediately after ablation. The kidneys were assessed for a contrast void corresponding to the ablated tissue. The kidneys were then harvested and the gross RFA lesions measured to compare lesion size with that measured using CEUS.


RESULTS
A clear lesion was identified at the site of each RFA application. As measured by CEUS, the acute lesions averaged 1.8 +/- 0.4, 1.7 +/- 0.4, and 1.8 +/- 0.3 cm in length, height, and width, respectively, compared with 2.0 +/- 0.5, 1.8 +/- 0.4, and 1.9 +/- 0.3 cm, respectively, by measurement in the gross specimen (P = 0.33, 0.13, and 0.44, respectively). At 1 week, the CEUS-measured dimensions of the lesions were 2.7 +/- 0.5, 2.6 +/- 0.6, and 2.6 +/- 0.6 cm, and the gross measurements of the lesion were 2.7 +/- 0.4, 2.7 +/- 0.9, and 2.6 +/- 0.4 cm (P = 0.75, 0.92, and 0.40, respectively).


CONCLUSIONS
Contrast-enhanced ultrasonography appears to be an accurate modality for immediate monitoring of RFA defects. Further study is necessary to assess the clinical utility of CEUS for monitoring RFA of small renal lesions.
Johnson
D Brooke
DB
The Clinical Center for Minimally Invasive Urologic Cancer Treatment, Department of Urology, The University of Texas Southwestern Medical Center, Dallas, Texas 75390-9110, USA.
Duchene
David A
DA
Taylor
Grant D
GD
Pearle
Margaret S
MS
Cadeddu
Jeffrey A
JA
D000818:Animals; D017115:Catheter Ablation / Q000379:methods*; D003287:Contrast Media; D005260:Female; D005466:Fluorocarbons; D007668:Kidney / Q000000981:diagnostic imaging* / Q000601:surgery*; D010535:Laparoscopy; D013552:Swine; D014463:Ultrasonography
D003287:Contrast Media; D005466:Fluorocarbons; C042852:perflutren