Accuracy of digital model generated from CT data with metal artifact reduction algorithm

Abstract

This study investigated whether metal artifact reduction (MAR) applied computed tomography (CT) scans could be used to generate precise digital models and explored possible correlations between the amount of metal artifact and model accuracy. Thirty maxillofacial CT scans were randomly selected and a MAR algorithm was applied. By subtracting the original and MAR-applied CT images, the amount of metal artifact was quantified. Digital models were generated from the original and the MAR-applied CT data. Paired digital models were superimposed and shape deviation in planar surface was measured at 10 points in 4 planes. Statistical analyses were performed to compare deviations and to assess correlations between the amount of artifact and deviation. The MAR algorithm reduced metal artifact in all cases. The overall mean deviation of the MAR-applied models was 0.0868 mm, with no significant difference according to the reference plane. The amount of artifact did not significantly influence the accuracy of the digital models. MAR-applied CT is a convenient source for digital modeling with clinically acceptable accuracy. The MAR algorithm can be used regardless of the amount of metal artifact, which are generated by dental prostheses, for the quick and convenient manipulation of dental digital models.

Figure 1

Schematic workflow of (A) the overall study procedure and (B) the metal artifact quantification procedure. MAR metal artifact reduction; STL standard tessellation language.

Figure 2

Determination of reference planes and measurement points on superimposed digital models for deviation assessment. The red line indicates a reference plane and the red dot indicates a point of measurement. The anatomical point of each reference plane is as follows. (A) A-point, (B) right mental foramen, (C) the lowest point of the right sigmoid notch, and (D) the lowest point of the left sigmoid notch. The starting point for the measurement points is the most superior or anterior point, with subsequent points automatically generated at the same interval.

Figure 3

Original CT and MAR-applied CT. (A) Axial view, (B) volume rendering image (bottom view), (C) volume rendering image (frontal view). Note the significant reduction of metal artifacts in the MAR-CT image compared to the original CT. MAR metal artifact reduction.

Figure 4

Scatter plot showing the correlation between the deviation (mm) of the MAR-applied model and the amount of metal artifact (mm²). No meaningful correlation is shown.