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.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Program Projects (P01)
Project #
5P01CA159992-02
Application #
8555397
Study Section
Special Emphasis Panel (ZCA1-GRB-P (M1))
Project Start
2011-09-22
Project End
2016-08-31
Budget Start
2012-09-01
Budget End
2013-08-31
Support Year
2
Fiscal Year
2012
Total Cost
$228,289
Indirect Cost
$74,984
Name
Stanford University
Department
Type
DUNS #
009214214
City
Stanford
State
CA
Country
United States
Zip Code
94305
Adams, Matthew S; Salgaonkar, Vasant A; Scott, Serena J et al. (2017) Integration of deployable fluid lenses and reflectors with endoluminal therapeutic ultrasound applicators: Preliminary investigations of enhanced penetration depth and focal gain. Med Phys 44:5339-5356
Gibbons, Eric K; Le Roux, Patrick; Vasanawala, Shreyas S et al. (2017) Body Diffusion Weighted Imaging Using Non-CPMG Fast Spin Echo. IEEE Trans Med Imaging 36:549-559
Ghanouni, Pejman; Kishore, Sirish; Lungren, Matthew P et al. (2017) Treatment of Low-Flow Vascular Malformations of the Extremities Using MR-Guided High Intensity Focused Ultrasound: Preliminary Experience. J Vasc Interv Radiol 28:1739-1744
Johnson, Ethan M; Vyas, Urvi; Ghanouni, Pejman et al. (2017) Improved cortical bone specificity in UTE MR Imaging. Magn Reson Med 77:684-695
Weber, Hans; Taviani, Valentina; Yoon, Daehyun et al. (2017) MR thermometry near metallic devices using multispectral imaging. Magn Reson Med 77:1162-1169
Dababou, Susan; Marrocchio, Cristina; Rosenberg, Jarrett et al. (2017) A meta-analysis of palliative treatment of pancreatic cancer with high intensity focused ultrasound. J Ther Ultrasound 5:9
Aggarwal, Kamal; Joshi, Kiran R; Rajavi, Yashar et al. (2017) A Millimeter-Wave Digital Link for Wireless MRI. IEEE Trans Med Imaging 36:574-583
Weber, Hans; Ghanouni, Pejman; Pascal-Tenorio, Aurea et al. (2017) MRI monitoring of focused ultrasound sonications near metallic hardware. Magn Reson Med :
Ghanouni, Pejman; Dobrotwir, Andrew; Bazzocchi, Alberto et al. (2017) Magnetic resonance-guided focused ultrasound treatment of extra-abdominal desmoid tumors: a retrospective multicenter study. Eur Radiol 27:732-740
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

Showing the most recent 10 out of 56 publications