Alternate Biplanar MR Navigation for Microwave Ablation of Liver Tumors

Abstract

Real-time MR (magnetic resonance) images in two perpendicular planes, both of which included the path of the needle, were utilized for MR-guided microwave ablation of liver tumors. The two image planes were automatically and alternately switched by new MR scanner control software installed on an external PC. This technique is possible only with MRI (magnetic resonance imaging) units with multiplanar and multisection capabilities. Reformatted images in the corresponding two planes were also constructed from preoperative three-dimensional volume data. These four images (two real-time and two reformatted) were continuously visible to the surgeons. These images enabled the needle position in the three-dimensional space to be accurately and clearly recognized, in contrast to the di‹culty encountered with two-dimensional MR images in a single image plane. This technique was also applied to MR temperature mapping during microwave ablation, as it allowed monitoring of the spread of the heat in a three-dimensional space. This type of computer-integrated image navigation was demonstrated to be feasible for MR-guided microwave ablation of liver tumors.

Real-Time Magnetic Resonance-Guided Microwave Coagulation Therapy for Pelvic Recurrence of Rectal Cancer: Initial Clinical Experience Using a 0.5 T Open Magnetic Resonance System

“…MR-Navi supports simple and accurate puncturing for large tumors. 20 Footprint enables surgeons to perform repeated punctures and ablations on irregular and large tumors. 37 Furthermore, MR images are not affected by bone and air space, or by microbubbles formed during ablation.…”

“…5A). 19,20,25,26 Microwave Coagulation Therapy A microwave coagulator, Microtaze (Model OT-110 M, Alfresa, Osaka, Japan), operated at 2.45 GHz, was used as a heating device (Fig. 5B).…”

MR thermometry for monitoring tumor ablation

“…Recent works demonstrated the feasibility of the combination of microwave hyperthermia system with MR temperature maps [54]. This technique was applied to the treatment of liver tumors [55] (see Fig. 3).…”

“…The color-coded scale on the right, overlaying the magnitude images, indicates the temperature increase. Reproduced with permission from [55] fibroids [6, 7] (see Fig. 4 from [6]) and breast cancer [8,9], demonstrating that MR temperature mapping is indeed feasible for guiding HIFU therapy.…”

Correlation between High Field MR Images and Histopathological Findings of Rat Transplanted Cancer Immediately after Partial Microwave Coagulation

“…Therefore, we have combined microwave ablation and MR image guidance using a 0.5-tesla, vertically oriented, open-conˆguration MR scanning system [9][10][11] and already performed MR-guided microwave coagulation therapy in over 200 patients with primary or metastatic liver tumors. MR temperature monitoring is useful in assessing therapeutic eŠects, but it is time consuming and di‹cult to apply to all sessions of repeated punctures and ablations during one procedure.…”