Disclosed is an apparatus for determining physiological parameter. The apparatus has an elongated magnetic probe, a driver coil arranged partially to surround the elongated magnetic probe, a measurement coil with at least a first section and a second section and a controller. The controller is configured to selectively energize the driver coil to create a magnetic force to initiate movement of the elongated magnetic probe to a direction of the first end, measure a first induced voltage and common induced voltage values, determine locator values as a function of time, map the locator values as a function of time from the time domain to a spatial domain and calculate from the spatial domain locator values, a first velocity profile of the elongated magnetic probe, and use the calculated first velocity profile of the elongated magnetic probe to determine the physiological parameter.