High Resolution 3D-CT and its Applications in Stereolithographic Computer Assisted Surgical and Implant Planning

Abstract

Until now 3D-CT reformatting has been used as a kind of presentation tool, providing impressive images with usually limited clinical relevance. The main disadvantage of this technique is a missing transscription from the calculated image to a solid model, which can be used by surgeons for a precise preoperative planning. First steps to overcome this disadvantage were made with milling models based on CT-Data. But the spatial resolution and therefore the representation of fine details like nerve ducts was not sufficient. The application of stereolithographic 3D-modelling on CT- and MR-Data is actually the only way to preserve the high resolution of the original images into the resulting 3D solid model. In common these models are used as a 3D-reproduction of the scanned — usually — bone structure for surgical procedure planning. The purpose of our study was to evaluate the precision of High Resolution CT and Stereolithographic Modeling for preopertaive implant constructions in patients with skull defects and planned large tumor resections in the facial area. The intention was to combine a precise preoperative, computer asssisted resection planning with a precise preoperative implant construction. Therefore Stereolithographic models were not made of the whole CT-Data, but only of the planned implant. Because there is — up to now — no polymeric material availiable which can be implanted and stereolithographic exposed, the stereolithographic implant models were used as a positive for casting a ceramic material. The resulting ceramic implants are 1:1 copies of the calculated stereolithographic model and can be implanted after sterilization.