Free-hand CT-based electromagnetically guided interventions: accuracy, efficiency and dose usage.

The purpose of this paper was to evaluate computed tomography (CT) based electromagnetically tip-tracked (EMT) interventions in various clinical applications. An EMT system was utilized to perform percutaneous interventions based on CT datasets. Procedure times and spatial accuracy of needle placement were analyzed using logging data in combination with periprocedurally acquired CT control scans. Dose estimations in comparison to a set of standard CT-guided interventions were carried out. Reasons for non-completion of planned interventions were analyzed. Twenty-five procedures scheduled for EMT were analyzed, 23 of which were successfully completed using EMT. The average time for performing the procedure was 23.7 ± 17.2 min. Time for preparation was 5.8 ± 7.3 min while the interventional (skin-to-target) time was 2.7 ± 2.4 min. The average puncture length was 7.2 ± 2.5 cm. Spatial accuracy was 3.1 ± 2.1 mm. Non-completed procedures were due to patient movement and reference fixation problems. Radiation doses (dosis-length-product) were significantly lower (p = 0.012) for EMT-based interventions (732 ± 481 mGy x cm) in comparison to the control group of standard CT-guided interventions (1343 ± 1054 mGy x cm). Electromagnetic navigation can accurately guide percutaneous interventions in a variety of indications. Accuracy and time usage permit the routine use of the utilized system. Lower radiation exposure for EMT-based punctures provides a relevant potential for dose saving.