Radiofrequency ablation (RFA) is emerging as an effective image-guided minimally invasive therapeutic alternative to surgical treatment of cancer tumors. RFA appears well suited to nonresectable tumors in liver. The ablation process is highly dependent on the electrical conductivity of these tissues yet there is no easy way to predict the current pathways or how focused the current will be on the tumor. For example, bone and fatty pockets can shield tumor from ablation currents. Consequently, repeatable ablation volumes are difficult to produce. Our goal is to enhance the planning, control and efficacy of tumor ablation by using an MRI system that can map RF ablation currents local to the electrodes during ablation and map thermal changes. RF current maps will show where power is being deposited, and MR thermometry will show where heat flowed during the ablation. Our approach exploits a new MRI technique that estimates RF current density in tissue. The ablation electrode can be injected with RF currents at the resonant frequency of the MRI scanner, and can also act as an MRI receiver. The MRI scanner can directly image the intense magnetic fields associated with the ablation current, and then derive the local electrode current flow to tissue. In our preliminary work, we have already visualized the current flow in an MR compatible ablation electrode. These tests demonstrated that fatty tissue effectively insulates and blocks the ablation current. Moreover, the current pathway itself lights up high conductivity tissue and creates a medically significant contrast. To fully exploit this capability, we will merge RF current mapping with MR thermometry and ablation devices to form a comprehensive interventional MRI system for RF ablation. Enhanced RF hardware, pulse sequences and reconstructions will be developed. Upon completion, we will perform ex-vivo tissue sample and in-vivo animal studies to demonstrate the clinical potential of this system.
MR guided RF ablation imaging and thermal monitoring should enable better treatment planning, and better control of RF ablation, thus improving time and spatial monitoring as tumor ablation progresses. MR guided RF ablation gives the patient an effective option for a minimally invasive treatment of cancer tumors and a more controllable therapy.
|Ellenor, Christopher W; Stang, Pascal P; Etezadi-Amoli, Maryam et al. (2015) Offline impedance measurements for detection and mitigation of dangerous implant interactions: an RF safety prescreen. Magn Reson Med 73:1328-39|
|Etezadi-Amoli, Maryam; Stang, Pascal; Kerr, Adam et al. (2015) Interventional device visualization with toroidal transceiver and optically coupled current sensor for radiofrequency safety monitoring. Magn Reson Med 73:1315-27|
|Scott, Serena J; Salgaonkar, Vasant; Prakash, Punit et al. (2014) Interstitial ultrasound ablation of vertebral and paraspinal tumours: parametric and patient-specific simulations. Int J Hyperthermia 30:228-44|
|Vyas, Urvi; Kaye, Elena; Pauly, Kim Butts (2014) Transcranial phase aberration correction using beam simulations and MR-ARFI. Med Phys 41:032901|
|Bitton, Rachel R; Pauly, Kim R Butts (2014) MR-acoustic radiation force imaging (MR-ARFI) and susceptibility weighted imaging (SWI) to visualize calcifications in ex vivo swine brain. J Magn Reson Imaging 39:1294-300|
|Rube, Martin A; Holbrook, Andrew B; Cox, Benjamin F et al. (2014) Wireless MR tracking of interventional devices using phase-field dithering and projection reconstruction. Magn Reson Imaging 32:693-701|
|Prakash, Punit; Salgaonkar, Vasant A; Diederich, Chris J (2013) Modelling of endoluminal and interstitial ultrasound hyperthermia and thermal ablation: applications for device design, feedback control and treatment planning. Int J Hyperthermia 29:296-307|
|Rieke, Viola; Instrella, Ron; Rosenberg, Jarrett et al. (2013) Comparison of temperature processing methods for monitoring focused ultrasound ablation in the brain. J Magn Reson Imaging 38:1462-71|
|Sommer, Graham; Pauly, Kim Butts; Holbrook, Andrew et al. (2013) Applicators for magnetic resonance-guided ultrasonic ablation of benign prostatic hyperplasia. Invest Radiol 48:387-94|
|Sommer, Graham; Bouley, Donna; Gill, Harcharan et al. (2013) Focal ablation of prostate cancer: four roles for magnetic resonance imaging guidance. Can J Urol 20:6672-81|
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