Mon, 29 Nov 2010 08:02 UTC
Stephen A. Boppart, study leader and physician at the University of Illinois, has developed a microscopy technique capable of providing easy-to-read results, and is also much faster than biopsy results.
Current diagnostic methods can take more than 24 hours to receive results. In addition, these tests are based on interpretations of cell structure and shape, meaning this type of testing is subjective. This type of testing requires the tissue in question to be drawn from the patient, and then mixed with a stain to make the cells easier to see. Then, under a microscope, the cells are observed and visually interpreted as either healthy or cancerous.
But the new technique, called nonlinear interferometric vibrational imaging (NIVI), offers color-coded images of tissues that highlight tumor boundaries clearly, making the test 99 percent accurate. Another major benefit is that results are generated in five minutes or less.
What makes NIVI so accurate is the way it assesses images. While current diagnostic methods concentrate on tissue and cell structure, NIVI builds images based on molecular composition. Researchers are able to distinguish healthy from cancerous cells easily because healthy cells have high concentrations of lipids while cancerous cells produce greater amounts of protein.
NIVI uses two beams of light to excite molecules in the tissue because each molecule has a different vibrational state of energy, and when the resonance of this vibration is altered, it can send a signal which can be used to differentiate cells with high concentrations of that molecule.
"The analogy is like pushing someone on a swing," said Boppart. "If you push at the right time point, the person on the swing will go higher and higher. If you don't push at the right point in the swing, the person stops. If we use the right optical frequencies to excite these vibrational states, we can enhance the resonance and the signal."
NIVI is able to eliminate background noise and isolate the molecular signal by using one beam as a reference and joining it with the signal created by the excited tissue sample. Then a statistical analysis of the "resulting spectrum" is performed, and a color-coded image is created at eah point in the tissue where red indicates cancer cells and blue indicates healthy cells. This red-blue color coding provides an uncertain boundary zone of 100 microns, which is only a cell or two, where current diagnostic methods have a margin of uncertainty that spans a large area of tissue, leaving them in the dark when trying to identify healthy from cancerous cell shapes.
"As we get better spectral resolution and broader spectral range, we can have more flexibility in identifying different molecules," said Boppart. "Once you get to that point, we think it will have many different applications for cancer diagnostics, for optical biopsies and other types of diagnostics."
This study will be published in Cancer Research on December 1.