Biomedical Engineering Reference
In-Depth Information
FIGURE 12.12
Robotically assisted spinal nerve blocks clinical trial at Georgetown University Medical Center. The interventional neuroradiolo-
gist used a joystick controlled robot to place the needle during the intervention.
ablation (RFA) for primary liver cancer, specifically hepatocellu-
lar carcinoma (HCC).
A common clinical scenario is that mostly hypervascular
HCC lesions occasionally do not have an abundant arterial vas-
cular supply, making them difficult to detect on angiography
and making TACE difficult to perform clinically. Conversely,
HCC lesions can have a sufficient vascular supply but be essen-
tially invisible without the use of iodinated contrast agents. This
makes the RFA procedure challenging as the lesions are hard
or impossible to see during the CT-guided ablation procedure.
Clinically, combination therapy is sometimes used where the
TACE procedure is done first and ethiodol is injected transar-
terially into the liver segment containing the tumor. This traps
the ethiodol in the tumor and allows subsequent visualization
during the RFA.
Navigation and image guidance could enable a more quan-
titative and scientifically reproducible approach to this therapy
by providing improved visualization of the tumor's vascular
supply to guide catheter position during the TACE procedure,
navigation assistance for precise placement of the RFA probe,
and intra-procedural feedback regarding quantitative treatment
assessment. The proposed workflow for such a system is shown
in Figure 12.13.
ablation probes or cryoprobes. This method of augmenting the
current clinical workflow is one potential path for improving
clinical outcomes. In tandem, improvements in imaging can
provide better visualization of tumor margins to enable more
complete tumor resection while preserving healthy tissue. The
concurrent use of reliable real-time feedback of the ablation pro-
cedure further maximizes the ability to obtain precise surgical
margins. Temperature sensors and imaging thermometry in
current use have their limitations. The evolution of these tech-
nologies to provide a more refined 3D view of the ablation pro-
cess will further improve clinical outcome. Used in conjunction
with this real-time feedback, simulation and modeling of the
ablation process has been shown to accentuate clinical practice.
Precise tissue margins and more focused tumor resection can
be made possible through the confluence of navigation, simu-
lation, modeling, and real-time feedback. Just as tracking of
tools has been shown to improve targeting accuracy, the use of
robotics such as remote manipulation of catheter systems and
robotic needle placement will further enhance this trend. The
use of medical robotics has increased in clinical practice across
the country in the last decade. Past the initial learning phase
involved with the use of a new device, reduction in procedure
times have been consistently noted. Planning and preoperative
simulation will also enable more complex procedures.
The complexity of biochemical processes related to tumor
growth and proliferation and the unique physiology of different
types of cancers have resulted in an appreciation of combination
therapy as an effective tool in the clinical armamentarium. While
a single treatment modality applicable for a broad range of cancer
types has remained elusive, and the notion now all but abandoned,
12.5 Summary
Navigation and image guidance for thermal cancer therapy is
an emerging area of research and clinical practice. Navigation
through the use of tracking systems has been shown to assist with
precision placement of instrumentation such as radiofrequency
