Real-time qualitative MR monitoring of microwave ablation in ex vivo livers

Abstract

The current ex vivo liver model experiment suggests that real-time qualitative MR monitoring of MWA is feasible. Further research using in vivo and human models are recommended.

Preclinical evaluation of an MR-compatible microwave ablation system and comparison with a standard microwave ablation system in an ex vivo bovine liver model

“…The frequency of RF ablation generators interferes with the MR scanner making imaging during the ablation procedure impossible without the use of additional filters [13,26]. However, microwave ablation generators work at higher frequencies of 915 MHz or 2.45 GHz, which may improve imaging control during an on-going ablation procedure [27].…”

Practical implementation of robust MR-thermometry during clinical MR-guided microwave ablations in the liver at 1.5 T

“…Furthermore, in our experience when the EMI was present it also tended to increase in intensity towards the end of ablations, as tissue properties changed (potential limitation of our QA testing using saline is that saline's properties remain constant during the MWG activation), occasionally still degrading the dose information. One potential approach to mitigate image quality degradation due to EMI is to interleave the ablation with MRI data acquisition, i.e., only acquiring MRI thermometry images when the microwave is temporarily powered off or in stand-by mode [22]. This approach, however, can potentially compromise the…”

“…In our practice MR-guided MWA treatments are performed using a commercially available MRI-configured microwave AveCure system (MedWaves Inc., San Diego, CA) operating at 902-928 MHz, inside a 1.5 T diagnostic horizontal bore scanner (Ingenia, Philips Healthcare, Best, Netherlands). The AveCure system in similar configuration has previously been used in MWA of ex-vivo porcine livers [22]. In that study the MR-monitoring was accomplished using the temperature-related signal changes in T1-weighted images.…”

“…Constraint 4: Modifications to MR thermometry acquisition protocol should not require periodic pausing in the microwave ablations. This approach, reported previously [22,27], could potentially have a negative impact on the effectiveness of the MWA therapy.…”

Improved Visualization of the Necrotic Zone after Microwave Ablation Using Computed Tomography Volume Perfusion in an In Vivo Porcine Model

“…For the latter, however, MRI-suitable materials are needed, and so far, most available devices are not MRI safe. However, if MRI-suitable materials can be used novel studies showed that MRI can accurately display the ablation zones and could also be used as real-time monitoring 27,28 . Still, accuracy of needle placement can be hampered in some MRI systems by the comparably narrow gantry, unless an open MRI system is used 29,30 .…”