Light-based imaging 'sees' thin fibrous cap

Autopsy studies indicate that soft plaque with a fibrous cap measuring less than 65 microns is at risk of imminent rupture. Multislice CT and MR imaging, with resolutions around 200 and 300 microns, respectively, cannot help predict a rupture. Optical coherence tomography (OCT), however, can obtain an in vivo resolution well below 65 microns.

Dr. Osamu Katoh and colleagues at Toyohashi Heart Center in Japan used OCT to measure minimal and maximal thickness and length of the fibrous caps in stable and vulnerable plaques (Am J Cardiol 2004;94[suppl 6A]:142E). Four lesions were considered vulnerable, and three were considered stable.

The mean minimal thickness of the fibrous caps was significantly less in the vulnerable group (30 microns) than in the stable group (70 microns). The differences in maximal thickness and length between the two groups were not significant.