In vivo validation of a therapy planning system for laser-induced thermotherapy (LITT) of liver malignancies.

PURPOSE: In situ ablation is increasingly being used for the treatment of liver malignancies. The application of these techniques is limited by the lack of a precise prediction of the destruction volume. This holds especially true in anatomically difficult situations, such as metastases in the vicinity of larger liver vessels. We developed a three-dimensional (3D) planning system for laser-induced thermotherapy (LITT) of liver tumors. The aim of the study was to validate the system for calculation of the destruction volume. METHODS: LITT (28 W, 20 min) was performed in close contact to major hepatic vessels in six pigs. After explantation of the liver, the coagulation area was documented. The liver and its vascular structures were segmented from a pre-interventional CT scan. Therapy planning was carried out including the cooling effect of adjacent liver vessels. The lesions in vivo and the simulated lesions were compared with a morphometric analysis. RESULTS: The volume of lesions in vivo was 6,568.3 ± 3,245.9 mm(3), which was not different to the simulation result of 6,935.2 ± 2,538.5 mm(3) (P = 0.937). The morphometric analysis showed a sensitivity of the system of 0.896 ± 0.093 (correct prediction of destructed tissue). The specificity was 0.858 ± 0.090 (correct prediction of vital tissue). CONCLUSIONS: A 3D computer planning system for the prediction of thermal lesions in LITT was developed. The calculation of the directional cooling effect of intrahepatic vessels is possible for the first time. The morphometric analysis showed a good correlation under clinical conditions. The pre-therapeutic calculation of the ablation zone might be a valuable tool for procedure planning.

Contrast-enhanced abdominal angiographic CT for intra-abdominal tumor embolization: a new tool for vessel and soft tissue visualization.

C-Arm cone-beam computed tomography (CACT), is a relatively new technique that uses data acquired with a flat-panel detector C-arm angiography system during an interventional procedure to reconstruct CT-like images. The purpose of this Technical Note is to present the technique, feasibility, and added value of CACT in five patients who underwent abdominal transarterial chemoembolization procedures. Target organs for the chemoembolizations were kidney, liver, and pancreas and a liposarcoma infiltrating the duodenum. The time for patient positioning, C-arm and system preparation, CACT raw data acquisition, and data reconstruction for a single CACT study ranged from 6 to 12 min. The volume data set produced by the workstation was interactively reformatted using maximum intensity projections and multiplanar reconstructions. As part of an angiography system CACT provided essential information on vascular anatomy, therapy endpoints, and immediate follow-up during and immediately after the abdominal interventions without patient transfer. The quality of CACT images was sufficient to influence the course of treatment. This technology has the potential to expedite any interventional procedure that requires three-dimensional information and navigation.