Clinical application of surface projection in the localization of metal foreign bodies using computed tomography scan

Objective: To analyse the clinical efficacy of surface projection in the localization and removal of metal foreign bodies using CT scan. Methods: Total 795 cases with 1008 metal foreign bodies were treated at our hospital in 2012. Pre-operative surface projection was performed to localize foreign bodies in patients under the guidance of CT scan. The removal path from the skin surface to foreign body and puncture site were then determined. Finally, the foreign bodies were extracted using proper foreign body forceps which were chosen according to the size, depth and position of the foreign bodies in different parts of the human body. The incision length, operative time and intraoperative blood loss were recorded. Additionally, outpatient follow-up was scheduled post-operatively for 1 week. Results: The accurate localization rate under the guidance of CT scan was 100%, and 1008 pieces of metal foreign bodies were all successfully removed with a removal rate of 100%. The mean incision length was 0.4 +/- 0.1 cm, the mean operative time was 4.1 +/- 2.0 min and the intraoperative blood loss was 1.1 +/- 0.5ml. These results showed minimal invasiveness, shorter operative time and minimal blood loss, respectively. Additionally, the results of outpatient follow-up showed that the wound healed spontaneously. Moreover, there were no significant bleeding, incision infections or complications. Conclusion: Surface projection may be an accurate and effective method for the pre-operative localization and extraction of metal foreign bodies. Advances in knowledge: (1) Surface projection was applied for localization of metal foreign bodies in our study. (2) The accurate localization rate of surface projection under the guidance of CT scan was 100%. (3) All foreign bodies were successfully removed with a removal rate of 100%. (4) Surface projection technique has advantages in the removal of foreign bodies.