PRELIMINARY EXPERIENCE WITH THE APPLICATION OF GADOLINIUM-DTPA BEFOREMR IMAGING-GUIDED LASER-INDUCED INTERSTITIAL THERMOTHERAPY OF BRAIN-TUMORS

The purpose of this study was to investigate the potential value of i. v. gadolinium-diethylenetriamine penta-acetic acid (Gd-DTPA) applied b efore MRI-guided laser-induced interstitial thermotherapy (LITT) of br ain tumors without original enhancement, especially in defining total lesion size during therapy. MRI-guided LITT was performed on two patie nts with astrocytoma WHO II. For both patients, Gd-DTPA was administer ed intravenously after a first irradiation period and LITT was continu ed after pulling back the light guide to coagulate the upper parts of the tumor. In both patients, the whole irreversible damaged zone of th e second irradiation period after Gd-DTPA showed an intense increase o f signal intensity. The spatial expansion correlated with the diameter of an enhancing rim after Gd-DTPA on follow-np studies. Our prelimina ry results indicate that the application of Gd-DTPA before MRI-guided LITT may be of value in defining exactly the size of the irreversible damaged zone during therapy in nonenhancing brain tumors.