Circular spirit level guidance system for CT- and MR-guided punctures

A circular spirit level guidance system was tested for control of CT- and M R-guided punctures. The device consists of a needle holder fixed to a groun d plate and two protractors. This allows adjustment of the fixed needle acc ording to the angulation of the supposed puncture path as measured on tomog raphic images. A circular spirit level is fixed to the needle and leveled. Now the needle can be removed from the needle holder; by leveling the circu lar spirit level during the puncture, the formerly adjusted angulation is a chieved. The system was tested in vitro and in vivo (22 patients) under CT and MR guidance. The average needle deviation was measured to be 1.96 degre es in vitro and 2.51 degrees in vivo. This simple device allows accurate pu ncture under CT and MR guidance.