Metal and motion artifacts by cone beam computed tomography (CBCT) in dental and maxillofacial study

This study aimed at evaluating incidence/degree of metal/motion artifacts and CT-dose-index in oral/maxillofacial examinations using Cone-Beam-CT.

Interferences caused by metal and motion artifacts were evaluated in 500 patients aged from 6 to 81 years, in dental arches, maxillofacial and splanchocranium Cone-Beam-CT exams. The interferences was divided into four progressive degrees (G0-G3) related to the possibility to answer the clinical query. The parameters considered were field-of-view, scan time, patient's age, and anatomical area. Furthermore volumetric CT-dose-index was measured.

In the presence of metal artifacts the clinical query was always answered (G3 = 0). No artifacts (G0) were found in all cases when metal was beyond 5 cm from interest site and in 18.4% when metal was inside this distance. Beam hardening and photon starvation due to implants, restoration and orthodontic therapies achieved 56.2% G1 and 25.4% G2. Motion artifacts were more frequent in under ten (31.5%) and over sixty (82.2%), and in mandible analysis (inferior arch 59.5%, both arches 47.3%). Moreover, their incidence and intensity were influenced by scan time (49.1% at 36 s) but not by field-of-view. Mean volumetric CT-dose-index of all patients was mGy 9.11 (mGy 3.62, 5.78, 8.89, and 13.07 at 18, 24, 26, and 36 s, respectively).

In our series Cone-Beam-CT diagnostic evaluation was never inhibited by metal artifacts and only in 1.9% of the cases by motion artifacts, always with a very low CT-dose-index.