Abstract 3427: Optical Pathlength Spectroscopy Predicts Fibrous Cap Thickness in Ex-Vivo Atherosclerotic Human Aortae
Background. Plaque rupture is the most frequent cause of sudden coronary death. Fibrous cap (FC) thickness of 65 μm or less has been identified as a key indicator of fibroatheroma instability. A clinical need exists for sensing techniques that can measure tissue structure at a micron level. We used a new tissue sensing modality, Optical Pathlength Spectroscopy (OPS), a transmural approach analyzing optical pathlengths of photons backscattered from tissue with micron resolution to evaluate the fibrous cap thickness of atherosclerotic lesions in ex-vivo thoracic aortae. The goal of this study was to assess the accuracy of FC thickness estimates from OPS signals.
Methods. Ninety human aortic fibroatheroma were interrogated with an OPS instrument under saline, using a precise x-y scanner. At each location, we acquired five OPS signals. After scanning, the interrogated locations were labeled, then stained with Movat. FC thickness was measured from the histology slides. OPS signal breakpoints corresponding to tissue layer boundaries were identified by two independent experts. OPS signal analysis and histology analysis were performed in a blinded fashion. Finally, regression analysis was performed on OPS-based FC thickness estimates vs. histological measurements.
Results. FC thickness estimates from OPS significantly correlated with FC thickness measured in histology with p < 0.00001 and a correlation coefficient r = 0.9055.
Conclusion. Optical Pathlength Spectroscopy, demonstrates sufficient depth resolution to determine the thickness of the fibrous cap and hence may be a promising technique for identifying thin cap fibroatheromas.