Summary: UCLA researchers in the Department of Radiological Sciences have developed a software-based active electromagnetic interference suppression solution for real-time MRI-guided interventions.
Background: Microwave ablation (MWA) has emerged as the preferred thermal ablation modality for treating non-surgical patients with primary and metastatic liver malignancies. The clinical success of thermal ablation depends critically on image guidance to ensure sufficient ablation margins while minimizing collateral thermal damage. Traditional image guidance, using modalities such as computed tomography (CT) and ultrasound, is constrained by limited soft tissue contrast and relies on surrogate markers of the ablation zone progression that do not reliably capture true ablation margins. These limitations reduce procedural precision and hinder real-time assessment of thermal dose delivery. Magnetic resonance imaging (MRI)-guided MWA addresses these shortcomings by providing superior soft tissue visualization and enabling real-time, non-invasive temperature monitoring through MR thermometry. This combination enhances targeting accuracy, intra-procedural monitoring, and treatment control, positioning MRI-guided MWA as a highly promising modality for minimally invasive tumor management.
However, broader clinical adoption of MRI-guided MWA remains limited by electromagnetic interference (EMI) emitted from MWA systems during active operation. EMI contaminates MRI data, obscuring visualization of the microwave antenna, tissue structures, and ablation zone boundaries — increasing the risk of incomplete treatment or collateral thermal damage. Beyond MWA, EMI poses challenges whenever insufficiently shielded powered devices are introduced into the MRI scanner room, constraining the range of MRI-conditional tools and monitoring equipment that can be used during procedures. Existing EMI mitigation approaches rely on specialized hardware modifications (e.g., additional shielding layers or in-line filters) or require suspending energy delivery during image acquisition. These approaches increase system complexity, disrupt therapeutic protocols, and are impractical for routine clinical workflows. Therefore, there is a critical need for a streamlined solution that enables reliable EMI suppression and integrates seamlessly into clinical workflows for MRI-guided interventions.
Innovation: To overcome the limitations of existing EMI mitigation approaches, researchers at UCLA have developed a software-based active EMI suppression (AES) framework that restores MRI signal integrity without requiring specialized hardware modifications or workflow disruptions. The framework leverages an unloaded body array coil—an existing clinical MRI system component—to capture raw EMI signatures independently of primary imaging data. This architecture enables seamless integration into existing MRI infrastructure without interfering with image acquisition or procedural workflow. The system characterizes and models the EMI signal on a frame-by-frame basis and adaptively subtracts it from the primary imaging coil data, enabling dynamic, real-time EMI suppression during active microwave ablation.
In controlled testing environments, the technology achieved a 40-fold signal-to-noise ratio (SNR) improvement in phantoms and a 13-fold improvement in vivo, with an EMI suppression rate exceeding 92%. These gains restore image fidelity sufficiently to enable consistent intra-procedural MRI visualization of anatomical details and ablation zone boundaries. The AES framework also preserves thermometric accuracy, maintaining a mean absolute temperature error of <1.4 °C in heated regions and <0.3 °C in non-heated tissue. This level of accuracy supports thermal dose monitoring and helps protect surrounding healthy structures. By eliminating the need for specialized shielding hardware or procedural workarounds, this software-driven AES solution directly addresses key infrastructure and workflow barriers and could facilitate broader clinical adoption of MRI-guided MWA and other MRI-guided interventions affected by EMI.
Potential Applications: ● MRI-guided Thermal and Non-Thermal Ablation ○ MWA, radiofrequency ablation, laser interstitial thermal therapy, focused ultrasound, cryoablation, pulsed field ablation, histotripsy ● MRI-Guided Surgical & Robotic Interventions ● Interventional Oncology & Cardiology ● Neuromodulation & Brain Interventions ● High-Risk Anatomical Interventions (e.g., proximity to critical structures) ● Relaxed MRI Suite Shielding Requirements ● Expanded MRI-Conditional Device Integration (e.g., monitors, tools, implants) ● Point-of-Care & Low-Field MRI Environments
Advantages: ● Streamlined Clinical Workflow ○ Continuous, real-time visualization ○ No pre-training or separate calibration needed ● Seamless Hardware and Software Integration ○ Leverages standard, existing MRI receiver coils — no custom hardware ○ Software-only solution, readily integrable into vendor or open-source reconstruction pipelines ● Superior Intra-procedural Image Quality Preservation ● Enhanced Patient Safety During Interventional Procedures ● Reliable Real-time MRI and MR Temperature Monitoring
Development-To-Date: First successful demonstration of the invention in controlled gel phantom and in vivo pig liver model
Related Papers: ● Dai, Qing, et al. “Active Electromagnetic Interference Suppression for Real-Time MR Thermometry During MR-Guided Microwave Ablation.” Annual Meeting of the International Society for Magnetic Resonance in Medicine (ISMRM), 2025, Honolulu, Hawai’i, USA, 0677.
Reference: UCLA Case No. 2026-217
Lead Inventor: Holden H. Wu