Effect of 3D ultrasound probes on the accuracy of electromagnetic tracking systems

In the last few years, 3D ultrasound probes have became readily available. New fields of image-guided surgery applications are opened by attaching small electromagnetic position sensors to 3D ultrasound probes. However, nothing is known about the distortions caused by 3D ultrasound probes regarding electromagnetic sensors. Several trials were performed to investigate error-proneness of state-of-the-art electromagnetic tracking systems when used in combination with 3D ultrasound probes. It was found that 3D ultrasound probes do distort electromagnetic sensors more than 2D probes do. When attaching electromagnetic sensors to 3D probes, maximum errors of 5 mm up to 119 mm occur. The distortion strongly depends on the electromagnetic technology as well on the probe technology used. Thus, for 3D ultrasound-guided applications using electromagnetic tracking technology, the interference of ultrasound probes and electromagnetic sensors have to be checked carefully.