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Evaluation of 3-dimensional superimposition techniques on various skeletal structures of the head using surface models.

Gkantidis N, Schauseil M, Pazera P, Zorkun B, Katsaros C, Ludwig B - PLoS ONE (2015)

Bottom Line: Although there was no difference among operators or between time points on the precision of each superimposition technique (p>0.05), the detected structural changes differed significantly between different techniques (p<0.05).Superimposition of 3D datasets using surface models created from voxel data can provide accurate, precise, and reproducible results, offering also high efficiency and increased post-processing capabilities.In the present study population, the BZ superimposition was comparable to AC, with the added advantage of being applicable to scans with a smaller field of view.

View Article: PubMed Central - PubMed

Affiliation: Department of Orthodontics and Dentofacial Orthopedics, University of Bern, Bern, Switzerland.

ABSTRACT

Objectives: To test the applicability, accuracy, precision, and reproducibility of various 3D superimposition techniques for radiographic data, transformed to triangulated surface data.

Methods: Five superimposition techniques (3P: three-point registration; AC: anterior cranial base; AC + F: anterior cranial base + foramen magnum; BZ: both zygomatic arches; 1Z: one zygomatic arch) were tested using eight pairs of pre-existing CT data (pre- and post-treatment). These were obtained from non-growing orthodontic patients treated with rapid maxillary expansion. All datasets were superimposed by three operators independently, who repeated the whole procedure one month later. Accuracy was assessed by the distance (D) between superimposed datasets on three form-stable anatomical areas, located on the anterior cranial base and the foramen magnum. Precision and reproducibility were assessed using the distances between models at four specific landmarks. Non parametric multivariate models and Bland-Altman difference plots were used for analyses.

Results: There was no difference among operators or between time points on the accuracy of each superimposition technique (p>0.05). The AC + F technique was the most accurate (D<0.17 mm), as expected, followed by AC and BZ superimpositions that presented similar level of accuracy (D<0.5 mm). 3P and 1Z were the least accurate superimpositions (0.790.05), the detected structural changes differed significantly between different techniques (p<0.05). Bland-Altman difference plots showed that BZ superimposition was comparable to AC, though it presented slightly higher random error.

Conclusions: Superimposition of 3D datasets using surface models created from voxel data can provide accurate, precise, and reproducible results, offering also high efficiency and increased post-processing capabilities. In the present study population, the BZ superimposition was comparable to AC, with the added advantage of being applicable to scans with a smaller field of view.

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Related in: MedlinePlus

Differences of the AC and BZ superimposition techniques from the gold standard technique.Bland-Altman plots of differences of the anterior cranial base (AC) or both zygomatic arches (BZ) superimposition techniques from the gold standard superimposition technique (anterior cranial base + foramen magnum: AC+F). These consider the measured structural changes induced by treatment at four specific points, measured by each operator, for all eight patients (P). The axes length represents the true range of observed values of structural changes.
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pone.0118810.g005: Differences of the AC and BZ superimposition techniques from the gold standard technique.Bland-Altman plots of differences of the anterior cranial base (AC) or both zygomatic arches (BZ) superimposition techniques from the gold standard superimposition technique (anterior cranial base + foramen magnum: AC+F). These consider the measured structural changes induced by treatment at four specific points, measured by each operator, for all eight patients (P). The axes length represents the true range of observed values of structural changes.

Mentions: Bland-Altman plots of differences of the AC from the gold standard (AC + F) superimposition showed that the measured structural changes were quite similar in most cases (median: -0.07; IQR: -0.20, 0.02; 95% CI: -0.31, -0.08). The higher differences were mostly in negative direction and mainly concerned two specific patients, implying a systematic error restricted to these cases (Figs. 5 & 6). Regarding the BZ superimposition, the measured structural changes were also quite similar to AC + F in most cases (median: 0.18; IQR: -0.20, 0.60; 95% CI: -0.06, 0.27). The distribution of differences tended to vary slightly more compared to the AC superimposition. The higher differences did not have a certain direction and were not attributed to selective patients (Figs. 5 & 6). There was no evidence that the extent of difference between techniques was related to the extent of structural changes in either case (Fig. 5). Thus, both superimposition techniques can be considered acceptable, though Bland-Altman plots reveal higher random error of the BZ superimposition. On the contrary, small systematic error may be evident in the AC superimposition (Fig. 6).


Evaluation of 3-dimensional superimposition techniques on various skeletal structures of the head using surface models.

Gkantidis N, Schauseil M, Pazera P, Zorkun B, Katsaros C, Ludwig B - PLoS ONE (2015)

Differences of the AC and BZ superimposition techniques from the gold standard technique.Bland-Altman plots of differences of the anterior cranial base (AC) or both zygomatic arches (BZ) superimposition techniques from the gold standard superimposition technique (anterior cranial base + foramen magnum: AC+F). These consider the measured structural changes induced by treatment at four specific points, measured by each operator, for all eight patients (P). The axes length represents the true range of observed values of structural changes.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4338241&req=5

pone.0118810.g005: Differences of the AC and BZ superimposition techniques from the gold standard technique.Bland-Altman plots of differences of the anterior cranial base (AC) or both zygomatic arches (BZ) superimposition techniques from the gold standard superimposition technique (anterior cranial base + foramen magnum: AC+F). These consider the measured structural changes induced by treatment at four specific points, measured by each operator, for all eight patients (P). The axes length represents the true range of observed values of structural changes.
Mentions: Bland-Altman plots of differences of the AC from the gold standard (AC + F) superimposition showed that the measured structural changes were quite similar in most cases (median: -0.07; IQR: -0.20, 0.02; 95% CI: -0.31, -0.08). The higher differences were mostly in negative direction and mainly concerned two specific patients, implying a systematic error restricted to these cases (Figs. 5 & 6). Regarding the BZ superimposition, the measured structural changes were also quite similar to AC + F in most cases (median: 0.18; IQR: -0.20, 0.60; 95% CI: -0.06, 0.27). The distribution of differences tended to vary slightly more compared to the AC superimposition. The higher differences did not have a certain direction and were not attributed to selective patients (Figs. 5 & 6). There was no evidence that the extent of difference between techniques was related to the extent of structural changes in either case (Fig. 5). Thus, both superimposition techniques can be considered acceptable, though Bland-Altman plots reveal higher random error of the BZ superimposition. On the contrary, small systematic error may be evident in the AC superimposition (Fig. 6).

Bottom Line: Although there was no difference among operators or between time points on the precision of each superimposition technique (p>0.05), the detected structural changes differed significantly between different techniques (p<0.05).Superimposition of 3D datasets using surface models created from voxel data can provide accurate, precise, and reproducible results, offering also high efficiency and increased post-processing capabilities.In the present study population, the BZ superimposition was comparable to AC, with the added advantage of being applicable to scans with a smaller field of view.

View Article: PubMed Central - PubMed

Affiliation: Department of Orthodontics and Dentofacial Orthopedics, University of Bern, Bern, Switzerland.

ABSTRACT

Objectives: To test the applicability, accuracy, precision, and reproducibility of various 3D superimposition techniques for radiographic data, transformed to triangulated surface data.

Methods: Five superimposition techniques (3P: three-point registration; AC: anterior cranial base; AC + F: anterior cranial base + foramen magnum; BZ: both zygomatic arches; 1Z: one zygomatic arch) were tested using eight pairs of pre-existing CT data (pre- and post-treatment). These were obtained from non-growing orthodontic patients treated with rapid maxillary expansion. All datasets were superimposed by three operators independently, who repeated the whole procedure one month later. Accuracy was assessed by the distance (D) between superimposed datasets on three form-stable anatomical areas, located on the anterior cranial base and the foramen magnum. Precision and reproducibility were assessed using the distances between models at four specific landmarks. Non parametric multivariate models and Bland-Altman difference plots were used for analyses.

Results: There was no difference among operators or between time points on the accuracy of each superimposition technique (p>0.05). The AC + F technique was the most accurate (D<0.17 mm), as expected, followed by AC and BZ superimpositions that presented similar level of accuracy (D<0.5 mm). 3P and 1Z were the least accurate superimpositions (0.790.05), the detected structural changes differed significantly between different techniques (p<0.05). Bland-Altman difference plots showed that BZ superimposition was comparable to AC, though it presented slightly higher random error.

Conclusions: Superimposition of 3D datasets using surface models created from voxel data can provide accurate, precise, and reproducible results, offering also high efficiency and increased post-processing capabilities. In the present study population, the BZ superimposition was comparable to AC, with the added advantage of being applicable to scans with a smaller field of view.

Show MeSH
Related in: MedlinePlus