V6-10: Novel percutaneous navigation system integrating GPS technology with movable tablet display of surgical 3D model for targeted focal therapy: initial experiences in human body.

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Introductions and Objectives
We present the first application of a percutaneous navigation system (Translucent™ Medical, Inc.) integrating GPS technology with a movable tablet display of virtual three dimensional (3D) models. The surgical tools and movable tablet display are tracked by GPS technology and digitally aligned with each other. The system displays real-time internal anatomy, superimposed surgical tools, and navigation aids (i.e. predictive puncture line). The objectives of this study were to assess the feasibility and accuracy of the system in targeted therapy for the prostate and kidney in cadaver.

Methods
Gold fiducial-markers (CIVCO Medical), which served as target centers of the virtual tumors (target-fiducial), were implanted in parenchyma of the kidney and prostate. A pre-op CT scan was obtained. The CT-DICOM data were transferred to the system to reconstruct into 3D surgical models. A needle with built-in GPS sensors was used as a therapeutic puncture needle. When the system indicated coincidence of the needle-tip and target-fiducial, another fiducial (treatment-fiducial) was placed through the outer-sheath of the therapeutic needle. A post-op CT was acquired to assess digitized distance between the 2 fiducials. For each target-fiducial, two placements of a treatment-fiducial were attempted (from two different skin incisions >20mm distant).

Results
Real-time display of the puncturing trajectory superimposed within the 3D model was used to successfully navigate the targeting in all procedures. Navigation was enhanced by color-coded changes to the needle-icon, indicating whether or not the current trajectory was on line to intersect the surgical target. Median time to target was 43 sec. Mean distance from needle-tip to target was 2.5mm (as calculated by the tracking system). Distance between the paired treatment-fiducials was 7.7mm. Distance between target-fiducial and treatment-fiducial was 16.6mm in the prostate and 12.0mm in the kidney. In an analysis of each axial component, errors were significantly greater along z-axis (p
Conclusions
This virtual navigation system, integration of GPS-technology with movable tablet display, is promising for percutaneous interventions. In order to minimize possible errors, further work is needed to augment the tracking system of intra-corporeal motions or deformations of the organs.

Funding: None