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.

Public Health Relevance

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.

National Institute of Health (NIH)
National Cancer Institute (NCI)
Research Program Projects (P01)
Project #
Application #
Study Section
Special Emphasis Panel (ZCA1-GRB-P (M1))
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Stanford University
United States
Zip Code
Johnson, Ethan M; Vyas, Urvi; Ghanouni, Pejman et al. (2016) Improved cortical bone specificity in UTE MR Imaging. Magn Reson Med :
Zhu, Kangrong; Dougherty, Robert F; Wu, Hua et al. (2016) Hybrid-Space SENSE Reconstruction for Simultaneous Multi-Slice MRI. IEEE Trans Med Imaging 35:1824-36
Marx, Michael; Butts Pauly, Kim (2016) Improved MRI thermometry with multiple-echo spirals. Magn Reson Med 76:747-56
Vyas, Urvi; Ghanouni, Pejman; Halpern, Casey H et al. (2016) Predicting variation in subject thermal response during transcranial magnetic resonance guided focused ultrasound surgery: Comparison in seventeen subject datasets. Med Phys 43:5170
Adams, Matthew S; Salgaonkar, Vasant A; Plata-Camargo, Juan et al. (2016) Endoluminal ultrasound applicators for MR-guided thermal ablation of pancreatic tumors: Preliminary design and evaluation in a porcine pancreas model. Med Phys 43:4184
Gaur, Pooja; Partanen, Ari; Werner, Beat et al. (2016) Correcting heat-induced chemical shift distortions in proton resonance frequency-shift thermometry. Magn Reson Med 76:172-82
Avedian, Raffi S; Bitton, Rachelle; Gold, Garry et al. (2016) Is MR-guided High-intensity Focused Ultrasound a Feasible Treatment Modality for Desmoid Tumors? Clin Orthop Relat Res 474:697-704
Ghanouni, Pejman; Dobrotwir, Andrew; Bazzocchi, Alberto et al. (2016) Magnetic resonance-guided focused ultrasound treatment of extra-abdominal desmoid tumors: a retrospective multicenter study. Eur Radiol :
Bitton, Rachel R; Webb, Taylor D; Pauly, Kim Butts et al. (2016) Improving thermal dose accuracy in magnetic resonance-guided focused ultrasound surgery: Long-term thermometry using a prior baseline as a reference. J Magn Reson Imaging 43:181-9
Adams, Matthew S; Scott, Serena J; Salgaonkar, Vasant A et al. (2016) Thermal therapy of pancreatic tumours using endoluminal ultrasound: Parametric and patient-specific modelling. Int J Hyperthermia 32:97-111

Showing the most recent 10 out of 48 publications