Fig. 1.

a OCT image of a human healthy coronary artery in vivo. The layered appearance of the wall is clearly visible. b Detail of the square region in (a), showing the lumen (L), the intima (I), media (M) and adventitia (A) layers, as well as the periadventitial tissues (P). c Intensity profile of the magenta line in (a, b). d Corresponding gradient. The extremum gradient values ${\mathrm{G}}_{0,1,2,3}$ correspond to the LI, IM, MA and AP interfaces, respectively