28.07.2018 | Original Article
Magnetic resonance imaging of third molars in forensic age estimation: comparison of the Ghent and Graz protocols focusing on apical closure
verfasst von:
Jannick De Tobel, Griet Iona Loïs Parmentier, Inès Phlypo, Benedicte Descamps, Sara Neyt, Wim Leon Van De Velde, Constantinus Politis, Koenraad Luc Verstraete, Patrick Werner Thevissen
Erschienen in:
International Journal of Legal Medicine
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Ausgabe 2/2019
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Abstract
Purpose
To compare the Ghent and Graz magnetic resonance imaging (MRI) protocols for third molars, focusing on the assessment of apical closure. To study the influence of (1) voxel size and (2) head fixation using a bite bar. To compare both protocols with a ground truth of apical development.
Materials and methods
In 11 healthy volunteers, 3T MRI was conducted, including four Ghent sequences and two Graz sequences, with and without bite bar. After removal, 39 third molars were scanned with 7T μMRI and μCT to establish the ground truth of apical development. Three observers in consensus evaluated assessability and allocated developmental stages.
Results
The Ghent T2 FSE sequence (0.33 × 0.33 × 2 mm3) was more assessable than the Graz T1 3D FSE sequence (0.59 × 0.59 × 1 mm3). Comparing assessability in both sequences with bite bar rendered P = 0.02, whereas comparing those without bite bar rendered P < 0.001. Within the same sequence, the bite bar increased assessability, with P = 0.03 for the Ghent T2 FSE and P = 0.07 for the Graz T1 3D FSE. Considering μCT as ground truth for staging, allocated stages on MRI were most frequently equal or higher. Among in vivo protocols, the allocated stages did not differ significantly.
Conclusion
Imaging modality-specific and MRI sequence-specific reference data are needed in age estimation. A higher in-plane resolution and a bite bar increase assessability of apical closure, whereas they do not affect stage allocation of assessable apices.