Interstitial Nd:YAG laser ablation in normal rabbit liver: trial to maximize the size of laser-induced lesions

In order to apply interstitial laser ablation to relatively small liver tumors in humans, it will be necessary to optimize the irradiation schedule. Nd:YAG laser was applied to normal rabbit liver in vivo at various power and energy outputs, including a protocol in which irradiation was repeated twice, with and without fiber tip advancement during the intermission. Ex vivo and in vivo tissue were also irradiated to determine the effect of perfusion on the lesion size. We obtained the same monotonic relationship between laser settings and lesion size in rabbit liver as we previously reported in rat liver. MR-guided fiber advancement between heating periods increased the transverse diameter of the lesion, and MR monitoring demonstrated this process. Our results suggest that repeated irradiation with brief intermissions, when combined with fiber advancement, may increase the lesion size.