Title: An Integrated System for ImageGuided Radiofrequency Ablation RFA of Liver Tumors
1An Integrated System for Image-Guided
Radiofrequency Ablation (RFA) of Liver Tumors
- Kevin Cleary, Ziv Yaniv, Georgetown University
- Noby Hata, Brigham and Womens Hospital
- Enrique Campos-Nanez, George Washington
University
2Liver tumor RFA
- Liver cancer that cannot be resected due to
extent and location of the disease or concurrent
medical conditions. - Introduce localized RF energy directly to tumor,
typically through expanding metal tines within a
small gauge insulated needle.
LeVeen probe
Before (left) and after (right)
treatment (courtesy of Brad Wood, MD, NIH CC)
3Overlapping Burns
- Large tumors can be treated with overlapping
spherical zones - Hard to visualize the overlapping areas
- Lack of real-time image guidance requires
repeated insertions to hit the target lesion and
establish sufficient margins
From Dodd, Soulen et al. 2000
4Project Overview
- Goal Develop an open source workstation for
liver RFA planning and treatment based on IGSTK
and Slicer. - Specific aims
- Develop and evaluate semi-automatic segmentation
techniques for the liver, liver vasculature, and
liver tumors. Georgetown, BWH - Develop a path planning module for evaluating
alternative paths to the liver tumor and
incorporating multiple overlapping placements as
needed for larger tumors. George Washington
University - Integrate the two capabilities developed above
along with electromagnetic tracking of the RFA
probe to provide a complete software environment
for liver tumor planning, visualization, and
execution. Georgetown, BWH - Validate the clinical feasibility of the system
in a swine animal model. Georgetown
5Timeline
Proposed
Actual
6SegmentationGold Standard Database
- Collected approximately 50 CT liver images from
Georgetown University Hospital - Followed Health Insurance Portability and
Accountability Act (HIPAA) rules for
anonymization of data - Medical student segmented 32 livers using
ITK-SNAP under supervision of attending
interventional radiologist - Next step is to segment tumors
7Path Planning
- Pre-emptive goal programming approach based on
integer programming techniques using a discrete
set of data points representing the tumor
(uniform sampling) - Minimize needle insertions (trajectories),
minimizes the number of punctures to the liver
capsule, and the number of needle insertions. - Minimizing Ablations Given needle trajectories.
- Minimizing Damage to Healthy Tissue
8Path Planning Status
- Currently implemented using commercial software
Xpress-MP (Fair Issac dash optimization) - Worked well in preliminary swine feasibility
studies - Now porting to open source Gnu Linear Programming
(GLPK) package - Initial results from porting are extremely slow
compared to commercial package - Requires further evaluation
9Integration
- Initial implementation started at IGT Project
Week in December 2008 in Boston - Tracking data is broadcast from IGSTK components
using OpenIGTLink protocol - Program resides in IGSTK sandbox and supports
FLTK GUI and command line mode
10Integration (continued)
- Specify configuration using xml files
- Supports multiple tools and broadcasting data to
multiple computers - Supports the use of a Dynamic Reference Frame. If
specified all broadcasted transformations will be
relative to the DRF (DRF transformation is not
sent) - Will present at SPIE Medical Imaging 2009 in
Orlando in February
lt?xml version"1.0" encoding"ISO-8859-1"?gt
lttracking_system type "polaris vicra"gt
ltrefresh_rategt 20 lt/refresh_rategt
ltserial_communicationgt ltcom_portgt4lt/com_por
tgt ltbaud_rategt115200lt/baud_rategt
ltdata_bitsgt8lt/data_bitsgt ltparitygtNlt/paritygt
ltstop_bitsgt1lt/stop_bitsgt
lthand_shakegt0lt/hand_shakegt
lt/serial_communicationgt lttool usage
"reference"gt ltnamegt large reference lt/namegt
11Next steps
- Goal is to create a Slicer3 workflow based
interface for navigated RFA (Nav-RFA) - Requirements document developed by Georgetown and
sent to BWH - Slicer will be configured with the following
modules - Data manage scene graph
- EM Segmenter potentially used for automatic
segmentation (maybe not in
the initial setup) - Editor manual segmentation and modification of
automated segmentation. - Fiducials marking the fiducials.
- Linear registration fiducial based registration.
- OpenIGTLink tracking
- This will create a skeleton end to end workflow
where we can fill in individual pieces and
improve as we go
12Summary
- Goal is to develop an integrated system for RFA
of liver tumors - Progress is good but vigilance needs to continue
- Open source implementation of optimization is one
concern