MRI-Guided and Controlled Laser-Induced Interstitial Thermal Therapy of Brain Tumors Using Integrated Navigation and Thermal Mapping

Abstract

Laser-induced interstitial thermal therapy (LITT) of brain tumors is a minimally invasive surgical technique for the treatment of solid brain tumors [17, 21]. The concept of MRI monitoring and control of LITT was introduced and experimentally proven by Jolesz (a-d) as early as 1988. The technique was tested in patients by Ascher in 1991 [1] and since has been reported in literatures by multiple investigators [2, 6, 10, 13, 16]. The results of these clinical trials demonstrate that MRI-guided LITT is a feasible and effective tool for primary and metastatic malignant brain tumor treatment. In the original study of Bettag et al., the laser fibers were inserted under CT guidance and treatment was monitored by T1-weighted MRI [2], or T1 images, while others used the water proton frequency shift-based phase mapping method [14, 27] to delimitate the extent of ablation. The usefulness of MRI-guided LITT was highlighted when Kath et al. reported imaging tumor with contrast agent (Gd-DTPA) and performed phase-sensitive temperature-sensitive sequences for MRI thermometry [12] ensuring the maximum coverage of thermal ablation over the lesions. Later, Kettenbach et al. reported the MRI-guided LITT performed completely under guidance by 0.5-tesla (T) MRI where special MRI made for intervention was also used to locate the tumor, positioning the fiber and monitoring the extent of ablation [13]. Similar works to perform MRI-guided LITT in a same 0.5 T scanner, but in more subjects, were published with 24 cases (7 low-grade gliomas, 11 anaplastic gliomas, 6 glioblastomas) [15] and 16 recurrent glioma subjects [25]. More recently, Carpentier et al. reported on treatment of brain metastasis using MRI-guided LITT in a closed bore 1.5 T scanner. The positioning of the cooled diffuser tip laser probe was done outside the scanner using a Leksell stereotactic head frame. After the patient was brought into the closed bore scanner, the ablation was monitored by temperature-sensitive MRI [3].