Abstract: The invention relates to a method and apparatus for detecting superparamagnetic material. The method comprises applying, by an excitation coil, a magnetic field during a first period to an object to modulate a magnetization of the superparamagnetic material, the magnetic field comprising a first component with a first frequency; positioning a sensing device at a first position from the excitation coil receiving a first signal by a first detection sub-coil in the sensing device and a second signal by a second detection-sub-coil in the sensing device; determining a sensor signal from the first signal and the second signal; determining a detection signal based on the sensor signal; determining a parameter indicating an amount of superparamagnetic material by dividing the detection signal by the first signal, and repeating steps to at at least one different position in order to determine a location where the parameter has a maximal value.