A system and method for ultrasound image guided surgical procedures such as needling or catheterisation, in which an ultrasound transducer is provided with a magnetometric detector for detecting the magnetic field emanating from a magnetised tissue-penetrating medical tool such as a needle or catheter. The detection of the magnetic field allows the position of the tool to be tracked magnetically and the position can be displayed on the ultrasound image. The position of the tool is determined from the magnetic field measurements by use of a look-up table of magnetic field values for the field emanating from the tissue-penetrating medical tool.
