This study was performed using paranasal CT images of 153 patients, aged 18–73 years, who presented at the department of radiology between January 2019 and May 2020 and approved by our local Ethics Committee with an approval number 2020/2906. For inclusion, healthy individuals without any pathology in the region were included in the study. Exclusion criteria included previous bony fracture or paranasal surgery, paranasal pathology, congenital craniofacial anomaly, and the imaging files with low-resolution. CT images were obtained using Somatom Drive (Siemens Healthineers, Germany) 256 multislice scanner with the following study parameters, exposure 120 kV, 74 mA, 60 mAs, rotation time 0.28 s, slice thickness 0.625 mm. CT images were evaluated by two experienced anatomists and one radiologist in consensus by use of Snygo-Via (Siemens, Germany) software. Measurements in sagittal, transverse, and coronal sections and images 3D were made at least twice by a radiologist and two anatomists, and their mean values were recorded.
Based on data provided in El-Anwar et al. [4], Maxwell et al. [10], and Sir et Eksert [17], all reformatted images were used to measure these surgical morphometric parameters from each side and gender discrimination:
1. On axial images,
- SPF-CA, the vertical distances from the SPF to the choanal arch (Fig. 1A),
- SPF-ML, the vertical distances from the SPF to the maxillary line (Fig. 1B),
- SPF-AH and SPF-BL, the anteroposterior distances from the SPF to the anterior head and basal lamella of the middle turbinate (Fig. 1C, D).
2. On coronal images,
- SPF-NF, the vertical distance from the SPF to the nasal floor (Fig. 2a),
- SPFD, the vertical diameter of the SPF (Fig. 2b),
3. On sagittal images,
- SPFA, the angle between SPF and the anterior nasal spine of the maxilla (Fig. 2*),
- OSPF-ANS, the oblique distance between the SPF and the anterior nasal spine of the maxilla (Fig. 2c),
- HSPF-ANS, the horizontal distance between the SPF and the anterior nasal spine of the maxilla (Fig. 2d).
Additionally, morphological variations of the SPF and the lateral nasal wall were evaluated as follows:
1. Septum deviation was classified into three types in the axial plane:
Type A: Deviation at the anterior part of the septum (Fig. 3A).
Type B: Deviation at the middle part of the septum (Fig. 3B).
Type C: Deviation at the posterior part of the septum (Fig. 3C).
2. The location of the SPF was identified according to the position of the middle turbinate as follows:
Type I: The posterior tip of the bony crest of the middle turbinate at the superior border of the SPF (Fig. 3D).
Type II: The posterior tip of the bony crest of the middle turbinate at the inferior border of the SPF (Fig. 3E).
Type III: The posterior tip of the bony crest of the middle turbinate at the middle of the SPF (Fig. 3F).
3. Pneumatization of the middle turbinate was identified as present (concha bullosa) or absent concerning laterality (Fig. 4A-C).
4. The number of SPF was noted (Fig. 5E, F) and the shape of the SPF was classified into five types: oval (Fig. 5A), circular (Fig. 5B), sandglass (Fig. 5C), fissure (Fig. 5D), and irregular.
Statistical analysis
Statistical analysis was performed using SPSS (the Statistical Package for the Social Sciences software version, Inc., Chicago, IL, the USA). Mann–Whitney U test, paired and unpaired t-tests were used to compare continuous variables concerning gender and sides, respectively. Categorical data was given as frequencies. One-way analysis of variance (ANOVA) was used to evaluate statistical differences between age groups, septum deviation types, and the SPF location types. A p value<0.05 was considered significant.