Tissue ablation with radiofrequency using multiprobe arrays.
OBJECTIVE
We studied the feasibility of increasing the volume of tissue destroyed by radiofrequency tissue coagulation using multiprobe arrays and defined parameters that determine lesion size and shape.


METHODS
Radiofrequency was applied to ex vivo calf liver using arrays of two to five 18-gauge probes for 6 min at 70-90 degrees C. Probe spacing (1-3 cm) and arrangement, as well as the method of radiofrequency application (simultaneous or sequential), were varied. The resulting areas of tissue coagulation were measured and compared.


RESULTS
Uniform tissue necrosis was observed with simultaneous radiofrequency application for probes 1.5 cm or less apart. At 1.5 cm, arrays of three equidistant probes produced spheroid lesions approximately 3.0 +/- 0.2 cm in diameter. Arrays of four equidistant probes produced cuboid lesions of 3.2 +/- 0.1 cm per side. However, probes placed 2 cm or more apart produced independent lesions 1.4 cm in diameter, with incomplete necrosis between probes. In the trials using five-probe arrays, a central region 4mm in diameter showed no visible evidence of tissue necrosis. With each array, lesion size varied less than 3 mm in any direction. Greater necrosis was accomplished when radiofrequency was applied simultaneously rather than sequentially.


CONCLUSIONS
Multiprobe radiofrequency arrays permit the destruction of more tissue in a single treatment session than is possible with multiple individual probes operating alone. Probes spaced 1.5 cm or less apart act synergistically, producing a total volume of coagulated tissue that is greater than when the individual probes are operated sequentially.
Goldberg
S N
SN
Department of Radiology, Massachusetts General Hospital, Boston 02114, USA.
Gazelle
G S
GS
Dawson
S L
SL
Rittman
W J
WJ
Mueller
P R
PR
Rosenthal
D I
DI
D000818:Animals; D017115:Catheter Ablation / Q000379:methods*; D002417:Cattle; D006358:Hot Temperature; D008099:Liver / Q000473:pathology / Q000601:surgery*; D009336:Necrosis