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17 Jun 2002
Portable, laser-based detection method benefits from biochemical boost
The development of infrared, laser-based devices for detecting malignant tumours in the breast has taken a step forward. Prof. Britton Chance and his team at the University of Pennsylvania have found a new method for improving the sensitivity and specificity of the technique, which is relatively well established but is not yet considered to offer significant improvements on success rates for conventional mammographic methods.
The group's innovation involves using a biochemical marker inside the body that significantly enhances the contrast between malignant and healthy cells. Tiny quantities of the marker, tricarbo-cyanine, are encapsulated within a peptide coating, and the capsules remain sealed until they reach specific enzymes associated with breast cancer. At this point the coating breaks down and, when illuminated from outside the body, the tricarbo-cyanine fluoresces enough near-infrared radiation for some of it to escape the breast and give a signal that can be picked up by a detector.
"The result is a contrast ratio of 20:1, compared with ratios of between 2:1 and 3:1 by more conventional methods," said Chance. "The molecular beacon is the real advance here, but I am also interested in making sure the apparatus is flexible and portable, so that a hand-held detection method can be made available to women who are under-served by or deprived of health services." Chance's detection device is based on off-the-shelf CD and cellphone technology and uses tiny infrared laser diodes for irradiation and detection.
The main challenge remaining is to get FDA approval for the protein-covered marker, which so far has been tested in mice but not in humans.
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