Evaluation of coronary adventitial vasa vasorum using 3D optical coherence tomography - Animal and human studies

- We studied 2 swine to verify OCT methods for quantification of vasa vasorum.
- We compared microchannel (MC) volume by OCT and vasa vasorum (VV) volume by micro-CT.
- Coronary reconstructed 3D OCT images from heart transplant recipients were analyzed.
- In the animal study, there were significant correlations between both the modalities.
- Human study showed a significant correlation between MC volume and plaque volume.

ObjectivesThis study sought to evaluate adventitial vasa vasorum (VV) in vivo with novel imaging technique of optical coherence tomography (OCT).MethodsTo verify OCT methods for quantification of VV, we first studied 2 swine carotid arteries in a model of focal angiogenesis by autologous blood injection, and compared microchannel volume (MCV) by OCT and VV by m-CT, and counts of those. In OCT images, adventitial MC was identified as signal-voiding areas which were located within 1 mm from the lumen-intima border. After manually tracing microchannel areas and the boundaries of lumen-intima and media-adventitial in all slices, we reconstructed 3D images. Moreover, we performed with OCT imaging in 8 recipients referred for evaluation of cardiac allograft vasculopathy at 1 year after heart transplantation. MCV and plaque volume (PV) were assessed with 3D images in each 10-mm-segment.ResultsIn the animal study, among the 16 corresponding 1-mm-segments, there were significant correlations of count and volume between both the modalities (count r2 = 0.80, P < 0.01; volume r2 = 0.50, P < 0.01) and a good agreement with a systemic bias toward underestimation with m-CT. In the human study, there was a significant positive correlation between MCV and PV (segment number = 24, r2 = 0.63, P < 0.01).ConclusionOur results suggest that evaluation of MCV with 3D OCT imaging might be a novel method to estimate the amount of adventitial VV in vivo, and further has the potential to provide a pathophysiological insight into a role of the VV in allograft vasculopathy.