ENDOVASCULAR ULTRASOUND. Photo essay from La Louvière clinic, France (59). Endovascular ultrasound is a technic of imagery that permits to study in real time (in vivo) the inner wall and the light of the vessels. The device is constituted by a generator of ultrasounds, that send a signal of a determined frequency to a transductor of small diameter, placed inside a catheter. The return signal is caracterised by an acoustic impedance, proportional to the density of the tissue and to the vel