Volumetric Evaluation of the Paranasal Sinuses with the Cavalieri Method
Mete Özdikici*
Department of Radiology, Bakirköy Training and Research Hospital, Turkey
Submission: April 23, 2018; Published: May 25, 2018
*Corresponding author: Mete Özdikici, Department of Radiology, Bakirköy Training and Research Hospital,İstanbul, Turkey, Tel: 00905065309467; Email: meteozdikici@hotmail.com
How to cite this article: Mete Özdikici. Volumetric Evaluation of the Paranasal Sinuses with the Cavalieri Method. Anatomy Physiol Biochem Int J: 2018; 5(2): 555657. DOI: 10.19080/APBIJ.2018.05.555657.
Abstract
Objectives:Our aim was to estimate the volumes of paranasal sinuses with Cavalieri principle.
Materials and Methods: The volumes of paranasal sinuses were estimated using the Cavalieri principle with coronal CT scans of 125 (68 male and 57 female) cases ranged from 18 to 75 years and analyzed by gender and age. The right-left comparison was also researched.
Results:The mean volumes (± S.D.) of unilateral sinuses were 6.0 ± 4.3, 19.1 ± 6.1, 5.7 ± 1.5 and 7.1 ± 3.9 cm3 for the frontal, maxillary, ethmoidal and sphenoidal sinuses, respectively. The volumes of paranasal sinuses were significantly different between the sexes (P < 0.05). There was no statistically significant difference between the right and left sinuses. However, the volume of paranasal sinuses gradually decreased after the third decade.
Conclusion:In this study, it is thought that the data obtained using the Cavalieri method will be useful in distinguishing between normal and pathological paranasal sinus volumes.
Keywords: Paranasal sinuses; Computerized tomography; Cavalieri method; Volume
Introduction
Various diseases, especially infections, can lead to changes in the volume of paranasal sinuses. Treatment methods, such as functional endoscopic sinus surgery, require knowledge of the detailed anatomy and volumes of the paranasal sinuses. Consideration of age-related changes in the size of paranasal sinuses is useful in detecting possible abnormalities [1-5]. In this study, we estimated the volume of paranasal sinuses using the Cavalieri principle on Computerized Tomography (CT) images. We also evaluated the effect of aging on the size of the paranasal sinuses.
Materials and Methods
The volumes of the paranasal sinuses were estimated by coronal CT scans in 125 (68 male and 57 female) cases. The ages of the patients ranged from 18 to 75 years. This study, approved by the Ethics Committee, was performed retrospectively and included patients who underwent paranasal sinus tomography due to any cause, but no pathological findings were detected. In the course of about 2 years, the cases that I evaluated normally were selected. The slice thickness on the CT images was 3-5 mm without a gap. Volume measurements are made by using a transparent template to overlay a grid of regularly spaced points over CT scans of randomly selected patients (Figure 1). Square grid test systems with two different point densities (d = 0.2, 0.3) between test points can use to estimate the total volume of the paranasal sinuses.
The choice of point density in the grid so that 100 to 300 points were counted for each CT study consistently yielded Coefficients of Error (CE) of 5% or less in volume measurements. This point is counted as the full contact of the counter. Counts are made three times. The double or middle number is used. The volume of an object appearing on a scan (V) is the product of the sum of points that fell on the object (ΣPi), the area associated with each point (ap), and the distance between scan slices (t) in cubic centimeters. {V=ΣPi.ap.t}. The statistical analysis was done by myself using the SPSS/PC version 15.0 package program. The volumes of sinuses were compared between the genders. It was analyzed in relation to age. The right-left comparison was also investigated. Pearson’s correlation test was used for the evaluation of the effects of aging on the size of paranasal sinuses.
Results
The mean volumes (cm3 ± S.D.) of four paranasal sinuses in males and females are shown in Table 1. The mean volumes of unilateral sinuses were 6.0 ± 4.3, 19.1 ± 6.1, 5.7 ± 1.5 and 7.1 ± 3.9 cm3; the mean volumes of bilateral sinuses were 12.5 ± 0.9, 37.2 ± 1.4, 11.9 ± 0.4 and 13.8 ± 0.8 cm3 for the frontal, maxillary, ethmoidal and sphenoidal sinuses, respectively. The total volume of all four paranasal sinuses was 82.1 ± 22.1 and 66.1 ± 14.6 cm3 for males and females, respectively. The paranasal sinuses of female subjects were 20% smaller than those of males. The mean CE of the volume estimates was 5%. The volumes of paranasal sinuses were significantly different between the sexes (P < 0.05). There was no statistical difference between the sides in either sex (P > 0.05). The volumes are higher at 20 years of age and then gradually decrease. There was a negative correlation with age on the total volume of all four sinuses (r = -0.240; P < 0.05).
Discussion
The paranasal sinuses consist of the frontal, maxillary, ethmoidal, and sphenoidal sinuses [2]. Because of the allergic and infectious diseases of the paranasal sinuses and nasal cavity, the sinonasal region is often radiologically imaged. It is important to know the paranasal sinus volumes in diagnosis, treatment, and follow-up of diseases such as infection, hypoplasia, sinus atelectasis, pneumosinus dilatans. Treatment methods, such as functional endoscopic sinus surgery, require that the volumes and detailed anatomy of the paranasal sinuses be well-known [1,3-6]. If a CT computer is not available for digital volumetric detection of lesions, the ellipsoid and Cavalieri methods may be an alternative. The Cavalieri estimator is more time consuming, although more reliable than the ellipsoid method [7,8].
Volume measurements from standard CT scans with the Cavalieri estimator can be made easily. It is suitable for daily clinical practice and is free of charge. This technique, which can be quickly applied with a portable transparent template, allows retrospective or prospective studies [6,9]. In our study, we combined the Cavalieri principle of stereological methods with CT scanning technique. The sum of the points that fell on the object, ΣPi, was then multiplied by the area associated with each point, ap (cm2), and the distance between slices, t (cm), to arrive at the volumes of related structures and organs, V (cm3). {V=ΣPi.ap.t} [9]. The choice of point density in the grid so that 100 to 300 points were counted for each CT study consistently yielded coefficients of error of 5% or less in our tumor volume measurements [6-10]. In our study, the mean CE of estimates was 5%.
The mean CE of frontal, maxillary, ethmoidal and sphenoidal sinuses were 6%, 3%, 5% and 5%, respectively. The unilateral mean volumes of frontal, maxillary, ethmoidal and sphenoidal sinuses were 6.0 ± 4.3, 19.1 ± 6.1, 5.7 ± 1.5 and 7.1 ± 3.9 cm3, respectively. Maxillary sinuses have the largest volume. In most of the studies it was determined that the paranasal sinus volumes were higher in males than females, these volumes decreased with age and the side difference was not significant [1-3,6,11-14]. In some rare studies, this difference between men and women is not statistically significant [15]. Our results also showed that the volumes of all paranasal sinuses are larger in males (P < 0.05). The paranasal sinuses of female subjects were 20% smaller than those of males. There was no statistically significant difference between the right and left paranasal sinuses (P > 0.05). It also revealed that the total volume of paranasal sinuses has a negative correlation with the age that means the paranasal sinus volume tends to decrease by the age of subjects (r = -0.240; P < 0.05).
Conclusion
In cases where the volumes of the paranasal sinuses are changing, it is important to know the normal volume limits if surgical treatment methods are needed. If there is no CT computer system, the measurement of paranasal sinus volumes obtained from CT scans using the Cavalieri principle can be evaluated as a practical and useful method. Moreover, the studies on the volume of all paranasal sinuses are extremely limited in the literature and it is clear that there is a need for new data to establish a standard in this respect. We think that our study will contribute to the formation of a standard in volume determination of paranasal sinuses.
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