Pathomorphology of laser-induced interstitial tumor thermotherapy for the liver

The aim of this study was to analyse pathomorphological findings after trea tment with laser induced tumor thermotherapy (LITT) on liver tissue and to correlate the results with magnetic resonance imaging. LITT was performed ex vivo and in vivo using a Neodym-YAG-Laser. Lesions we re monitored by MR-thermometry ex vivo and by contrast-enhanced MRI in vivo . After LITT the lesions were examined macroscopically, histologically,and electronmicrosopically. LITT-induced tissue damage was qualitatively evalua ted, classified, and quantified by means of digital image analysis. Four different zones of tissue damage were identified within the lesions. A djacent to the applicator the tissue was completely ablated while more peri pheral lesions exhibited only sublethal cell damages seen by EM. In vivo th e pattern of tissue injury followed the lobular architecture of the liver t issue. Ultrastructural examination revealed only in areas of minor tissue i njury intact sinusoidal patterns. MRI overestimated the diameter of the cor e zone of complete tissue ablation both ex vivo and to a lesser extent in v ivo.