Abstract

The current tumor to tissue ratio obtained with intrinsic and extrinsic contrast agents is limited to approximately 2- to 3-fold and with this contrast, sensitivity/specificities of 80-90% are to be expected taking into account false positives due to cysts and false negatives due to adinocarcinomas which may not have fully developed angiogenic expression. Improved results have been obtained by combining multiple co-registered measures, for example, blood volume and deoxygenation, and other biochemical and physiological features, together with imaging of adequate resolution to include congruence of position of these images, increasing the sensitivity/specificities significantly towards 90%. Our next step in improving cancer detection is to increase the tumor to tissue ratio towards a factor of 10 and above. This can best be achieved by site directed, overt or stealth molecular beacons as described here. Furthermore, localization of the beacon signal with adequate accuracy for fine needle aspiration must be available in order to achieve a clinically acceptable diagnostic capability of the molecular beacon.

© 2002 Optical Society of America