Three dimensional comparative measurement of polyurethane milled skull models based on CT and MRI data sets

ObjectiveDue to the increase in the number and complexity of surgical procedures, available to craniomaxillofacial surgeons, allied to the rapid progress of technological developments, the use and production of 3D models has become important, especially for planning complex cases. The radiation exposure of additional CT based examinations is always subject to debate, so the feasibility of producing 3D models for surgical planning based on MRI imaging has been raised.Material and methods12 male and 3 female patients (n = 15) between 47 and 84 years of age (mean age = 65) were selected in a prospective study. Both magnetic resonance and computed tomography data sets of the facial bones were collected. Two milled models per patient were prepared: one based on the MRI scan and one based on the CT scan. The milled models were compared in a coordinative surveying procedure within 7 representative distances using a tentative measurement method.ResultsDifference values between CT and MRI based models ranged from 0.1 mm to 5.9 mm. On average MRI based models were smaller by 0.381 mm (SD 1.176 mm) than those on CT based. The accuracy of models based on MRI data was similar to those based on CT data. MRI based three dimensional milled models provide precise structure accuracy.