Gd. Dodd et al., Radiofrequency thermal ablation: Computer analysis of the size of the thermal injury created by overlapping ablations, AM J ROENTG, 177(4), 2001, pp. 777-782
Citations number
21
Categorie Soggetti
Radiology ,Nuclear Medicine & Imaging","Medical Research Diagnosis & Treatment
OBJECTIVE. The purpose of this study was to perform a computer analysis of
the size of the thermal injury created by overlapping multiple thermal abla
tion spheres.
MATERIALS AND METHODS. A computer-assisted design system was used to create
three-dimensional models of a spherical tumor, a spherical tissue volume c
onsisting of the tumor plus a 1-cm tumor-free margin, and individual spheri
cal ablations. These volumes were superimposed in real-time three-dimension
al space in different geometric relationships. The effect of the size and g
eometric configuration of the ablation spheres was analyzed with regard to
the ability to ablate, the required volume of tissue (tumor plus margin) wi
thout leaving untreated areas or interstices.
RESULTS. The single-ablation model showed that if a 360 degrees 1-cm tumor-
free margin is included around the tumor targeted for ablation, radiofreque
ncy ablation devices producing 3-, 4-, and 5-cm ablation spheres can be use
d to treat 1-, 2-, and 3-cm tumors, respectively. The six-sphere model, in
which six ablation spheres are placed in orthogonal planes around the tumor
, showed that the largest tumor that may be treated with a 3-cm ablation de
vice is 1.75 cm, whereas 4- and 5-cm ablation spheres can be used to treat
tumors measuring 3 and 4.25 cm, respectively. The 14-sphere model showed th
at addition of eight more spheres to the six-sphere model increased the tre
atable tumor size to 3, 4.6, or 6.3 cm, depending on the diameter of the ab
lation sphere used. For treating larger tumors, we found a cylindrical mode
l to be less efficient but easier to control.
CONCLUSION. Our computer analysis showed that the size of the composite the
rmal injury created by overlapping multiple thermal ablation spheres is sur
prisingly small relative to the number of ablations performed. These result
s emphasize the need for a methodic tumor ablation strategy.