The invention presents an apparatus (6) for characterization of a condition of a vessel (12) wall of a living being (2). The relationship between temporal blood pressure (621) and blood flow (622) measurements of pulsatile blood motion within the vessel (12) is an indication of the health of the vessel (12) wall. Furthermore, the invention discloses a system (1) comprising the apparatus (6), and a method (100) of characterizing the condition of vessel (12) walls.