Material and Methods
Study was conducted in the Department of Dentomaxillofacial radiology ofXXX University, Faculty of XXX , between
January-November 2019, with ethical approval number: 08/03 given by the
faculty Clinical Research Ethics committee and with ClinicalTrials.gov
ID: NCTXXX . The study has been carried out in accordance with
The Code of Ethics of the World Medical Association. Computed tomography
scans of 120 patients (59 maxillary deficiency patients and 61 control)
were included in the study. CT scan indications for the group with
maxillary deficiency was surgical preparation for maxillary advancement
with Le Fort I osteotomy. The control group had no maxillary deficiency
and CT images were obtained for several other indications such as
temporomandibular disease. CT scans of patients with a history of trauma
in the midline skull base, and with the presence of sinus diseases such
as chronic sinusitis, nasal polyps, and tumors were excluded from the
study.
Imaging procedures: CT imaging’s were performed using
various CT scanners (GE Lightspeed 16 slice, GE Medical Systems,
Milwaukee WI, US; Siemens Somaton Sensation, 16 slice, Siemens Medical
Solutions, Erlangen, Germany) at 120 kVp and 25 mA with a display matrix
of 256X256. Images were processed and measured using 3D Synapse Software
(Fujifilm, Tokyo, Japan). The CT data were transferred as DICOM files to
the software for measurements. The volumes (mm3) were
measured as semiautomatic segmentation of the right and left maxillary
sinuses, and the ethmoid and sphenoid sinus. For segmentations, the
thresholding was limited to a minimum of 1024 HU and a maximum of 526
HU. 6 The ethmoid and sphenoid sinuses were sculpted
out from these 3D images. Semiautomatic segmentation was performed to
include the entire paranasal sinus anatomies (Figure 1, 2 and 3).
For maxillary sinuses, those were clipped according to the surrounding
bone structure and the narrowest area of the ostium between the
infundibulum and the processus uncinatus using the software’s “edit
masks” tool. Then, the connection with the outside air was interrupted
by slice using segmentation tools. The “region growing” tool was used
to divide the segmentation created by thresholding several objects and
remove the floating pixels. The paranasal sinuses then were
automatically calculated using the software analysis tool. Presence of
Onodi cells were noted.
All measurements were taken twice by two blinded radiologists. The
radiologists performed the study twice with an interval of 2 weeks to
detect intra-observer variability.
Statistical analysis: The analysis of the data was done
in SPSS version 11,5. As descriptive, mean ± standard deviation and
median (minimum - maximum) were given for quantitative variables, and
number (percentage) was given for qualitative variables. To assess
intra-observer reliability, the Wilcoxon matched pairs signed rank test
was used for repeat measurements.
In terms of the quantitative variables, the difference between the
categories of the qualitative variable with two categories was examined
using Student-t test if normal distribution assumptions were provided,
and Mann Whitney U test if not. When the difference between two
dependent quantitative variables was to be examined, the Wilcoxon Signed
Rank test was used, since normal distribution assumptions were not
provided. Chi-square test was used to examine the relationship between
two qualitative variables. Statistical significance level was taken as
0,05.