The present invention relates to an extracorporeale interface unit (8), for an intravascular measurement system for measuring a physiological, or other, variable in a living body, being adapted to generate a sensor signal in response of said variable. The interface unit (8) comprises a sensor interface circuitry (6) adapted to interface a sensor wire configured to be inserted into the living body and provided with one or many sensor element(s) at its distal region. The sensor interface circuitry (6) further comprises a measurement unit (9) adapted to generate the measured data of the variable as a sensor signal. The sensor interface circuitry (6) comprises two current source units (CSU1, CSU2) adapted to energize the sensor element(s) via at least two connection points (CP 1, CP2,... CPn), and a switching unit (10), wherein the switching unit (10) is adapted to alternately switch connection between the current source units (CSU l, CSU2) and at least two of the connection points (CP1, CP2,... CPn), using a preset switching frequency having essentially the same connection time period (Tc) for each connection. The measurement unit (9) is adapted to determine a sensor variable value (Vdiff) related to the variable at two of the connection points (CP1, CP2,... CPn). The present invention further relates to a measurement system (12) comprising said extracorporeale interface unit (8) and a method in said interface unit.La présente invention porte sur une unité d'interface extracorporelle (8), pour un système de mesure intravasculaire servant à mesurer une variable physiologique ou autre dans un corps vivant, qui est conçue pour générer un signal de capteur en réponse à ladite variable. L'unité d'interface (8) comprend un circuit d'interface de capteur (6) conçu pour servir d'interface avec un fil de capteur configuré pour être introduit dans le corps vivant et comportant un ou de nombreux éléments de capteur au niveau de sa région distale. Le circuit d'interface de capteur
