Tissue optical properties have become an increasingly promising avenue of diagnosis and screening for cancers and may provide contrast for real time monitoring of tumor ablation therapy. Of particular interest, are methods that can quantify scattering properties while providing spatial context or a map of the tissue being measured. Optical Coherence Tomography (OCT) is a non-destructive imaging modality with high 3D resolution which can be miniaturized into a probe compatible with common endoscopes. OCT has recently been used to quantify optical scattering properties, and endoscopic access to luminal organs allows examination of the thin epithelial layer, wherein many cancers originate.
We present a fiber probe capable of quantifying optical properties with no distal optics providing low-cost disposable functionality. A reflection from the distal fiber face provides a common path reference through the fiber and eliminates the need for reference arm with dispersion compensation. A custom visible light OCT instrument was adapted to the self-reference fiber capable of a-scan imaging hundreds of microns into porcine esophagus tissue. B-scan images are produced by dragging the fiber along the tissue surface. Tissue was thermally ablated to create controllable scattering contrast with normal tissue. Image analysis with a custom MATLAB algorithm demonstrated significant increases in scattering coefficients which has been observed previously in a benchtop scanning OCT system.
Visible light maximizes scatter contrast making Vis-OCT an ideal tool for cancer screening. Additionally, the lack of a distal optics and scanning mechanism offers a cost-effective, disposable functionality.
Microwave tumor ablation continues to evolve into a viable treatment option for many cancers. Current systems are
poised to supplant radiofrequency ablation as the dominant percutaneous thermal therapy. Here is provided an overview
of technical details and early clinical results with a high-powered, gas-cooled microwave ablation system.
The system was developed with academic-industry collaboration using federal and private funding. The generator
comprises three synchronous channels that each produce up to 140W at 2.45GHz. A mountable power distribution
module facilitates CT imaging guidance and monitoring and reduces clutter in the sterile field. Cryogenic carbon-dioxide
cools the coaxial applicator, permitting a thin applicator profile (~1.5 mm diameter) and high power delivery.
A total of 106 liver tumors were treated (96 malignant, 10 benign) from December 2010 to June 2012 at a single
academic institution. Mean tumor size ± standard deviation was 2.5±1.3cm (range 0.5-13.9cm). Treatment time was
5.4±3.3min (range 1-20min). Median follow-up was 6 months (range 1-16 months). Technical success was reported in
100% of cases. Local tumor progression was noted in 4/96 (4.3%) of malignancies. The only major complication was a
pleural effusion that was treated with thoracentesis.
Microwave ablation with this system is an effective treatment for liver cancer. Compared to previous data from the same
institution, these results suggest an increased efficacy and equivalent safety to RF ablation. Additional data from the lung
and kidney support this conclusion.