Table 1.
Parameters of the used MRI sequence.
Fig 1.
Cephalometric landmarks used in the present study.
A total of 10 midsagittal (blue marked) and 8 bilateral (red marked) landmarks were included in cephalometric analysis: S = Sella; N = Nasion; ANS = Anterior nasal spine; PNS = Posterior nasal spine; A = Point A (most concave point of anterior maxilla); B = Point B (most concave point of mandibular symphysis); Is = Incision superius; Ii = Incision inferius; As = Apex superius; Ai = Apex inferius; Pg = Pogonion (most anterior point of mandibular symphysis); Gn = Gnathion (midpoint between Pg and Me); Me = Menton (most inferior point of mandibular symphysis); D = Point D (geometric center of the symphysis); Go = Gonion; tGo = Gonion tangent point (intersection between the mandibular line and the ramus line); Ar = (junction between inferior surface of the cranial base and the posterior border of the ascending rami of the mandible); ppOcc = posterior point of occlusion.
Fig 2.
Workflow applied in the present study for each patient (n = 20) is shown.
I = A multiplanar reconstruction (MPR) along the anatomic sagittal plane was acquired from primary magnetic resonance imaging (MRI) datasets. II = The midsagittal plane is coloured in red for better visualization of the workflow. Nine slices containing the landmarks necessary for cephalometric analysis were selected (1). The paired lateral slices were cropped preserving the relevant landmarks on the left (2a) and right (2b) side. The midsagittal plane and the 8 cropped lateral slices were merged into a lateral MRI cephalogram (3). III = Lateral cephalometric analysis was performed on lateral MRI cephalograms and corresponding lateral cephalometric radiographs (LCR) with dedicated software. For each modality two observers placed 10 midsagittal and 8 bilateral landmarks from which 14 angles and 10 distances were calculated automatically by software. Measurements were taken twice with an interval of 4 weeks.
Table 2.
Cephalometric measurements performed in the present study.
Table 3.
Interobserver and intraobserver agreement for lateral cephalometric measurements.
Fig 3.
Bland-Altman plots show the differences between the measurements on LCR and lateral MRI cephalograms.
Solid lines represent the mean of all differences (bias), dashed lines represent the 95% limits of agreement. Exemplary measurements according to Steiner’s analysis [14] are shown in this figure: (a) SNA-angle, (b) SNB-angle, (c) ANB-angle, (d) SND-angle, (e) Ui/NA-angle, (f) Is/NA-distance, (g) Li/NB-angle, (h) Ii/NB-distance, (i) Pg/NB-distance, (j) Ui/Li-angle, (k) SN/OcP-angle and (l) SN/GoGn-angle.
Table 4.
Lateral cephalometric measurements from LCR and MRI (n = 20).