Laser-induced thermotherapy (LITT) for malignant liver tumours: the role of sonography in catheter placement and observation of the therapeutic procedure

Abstract

Evaluation of sonography in the placement of catheters for laser-induced thermotherapy (LITT) as well as for the observation of the therapeutic procedure in cases of malignant liver tumours. Following the placement of 1-4 LITT applicators, 18 patients with malignant liver tumours (recurrence of hepatocellular carcinoma n = 5, metachronous liver metastases n = 13) were examined by ultrasound to determine the position of the applicators as well as the sonographic visualisation of the respective lesion. The laser treatment procedure was also observed sonographically. As standard reference method for the documentation of thermally induced necroses we used magnetic resonance tomography 24-48 hours after the procedure. The tip of the applicator could be localised in all cases, and the position of the applicator relative to the lesion could be directly visualised in 78% of cases. The hyperechogenic thermal effect during LITT had a median size of 4.5 cm, thus proving to be significantly larger than the actual necrosis induced (p < 0.01). The sonographic observation of the procedure identified 8/10 primarily incomplete ablations which were then treated again immediately after correction of the position of the applicators. Continuous sonographic observation of the procedure of LITT can yield important additional information.