Evaluation of Sella Turcica Types Using Cone-beam Computed Tomography

doi:10.21203/rs.3.rs-1554113/v1

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Research Article

Evaluation of Sella Turcica Types Using Cone-beam Computed Tomography

https://doi.org/10.21203/rs.3.rs-1554113/v1

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Purpose

To investigate the morphological types of sella turcica on cone-beam computed tomography (CBCT) images in a group of Turkish population by mean age and gender with two different classifications.

Methods

Full head CBCT images of 1000 patients (535 men, 465 women) aged 6–91 years were retrospectively analyzed. The morphological types of sella turcica were evaluated in the multiplanar planes of CBCT according to two classification systems and the relationship between them was examined. Relationships between categorical variables were analyzed with the χ2 test.

Results

Normal type of sella turcica was detected in 532 (53.2%) of 1000 patients. The frequency of the other morphological types of sella turcica were as follows, respectively: irregularity (notching) in the posterior part of the dorsum sella 40.9%, sella turcica bridging 2%, pyramidal shape of dorsum sella 1.7%, oblique anterior wall 1.2%, double contour of sellar floor 1%. The frequency of basic morphological types of sella turcica was as follows: oval 48%, flattened 34.7%, circular 17.3%. The flattened type of the basic morphological sella types was significantly higher in males (p < 0.001). Except for this type, there was no significant difference between the genders. Irregularity (notching) in the posterior part of sella turcica type was observed significantly more in cases where the basic morphological sella types were flattened (p < 0.001).

Conclusions

A higher rate of normal sella morphology was detected on CBCT compared to studies conducted in a wide age range. Oval sella was mostly observed with normal sella, and the flattened sella was mostly determined with irregularity in the posterior part of the dorsum sella. CBCT is a useful technique to examine the morphological types of sella turcica.

Sella turcica

morphology

cone-beam computed tomography

sphenoid bone

The sella turcica is a saddle-shaped depression in the sphenoid bone that contains the pituitary gland [2]. It was named "Sella turcica" because the anterior and posterior bone protrusions of the region seen in the lateral head images are similar to the Turkish saddle [18]. It has important anatomical proximity such as optic chiasma, sphenoid sinus, etc [24]. When tomography images and conventional two-dimensional posteroanterior radiographs are evaluated, it is seen that the sella floor is a flat or downward convex structure in healthy individuals, with a maximum depth of 3.5 mm in the middle region. In the presence of pathologies, the convexity of the fossa may increase or the fossa may become shallow [11].

Orthodontists, who frequently refer to lateral cephalometric radiographs during clinical practice, often ignore the sella turcica area, except to determine the “sella” point. Detectable changes in the size and morphology of this region, together with clinical symptoms, may be useful in the early diagnosis of some diseases [3]. Sella bridging has been found to be more common in patients with severe craniofacial anomalies [6, 12]. Sella shape and size can also be affected by pathological conditions such as Down syndrome, Williams syndrome, Seckel syndrome and Lumbosacral myelomeningocele [4, 13, 22].

It is not possible to verify the third-dimensional data on conventional lateral cephalometric radiography [8]. With the development of imaging diagnosis and methods, it has made it possible to examine and characterize the normal anatomy and morphology of human body structures using computed tomography (CT) images [21]. Cone-beam computed tomography (CBCT) is a more reliable method for examining bone structures due to its low dose and short scan time [16].

To determine whether the sella turcica has an abnormal appearance, it is necessary to know its normal morphological appearance. In previous studies, different evaluations were made about the morphology of sella turcica. Camp [7] divided sella turcica into three types: circular, oval and flat. Axelsson et al. [5] classified sella morphologically into six types on lateral cephalometric radiographs. These are: normal, oblique anterior wall, sella turcica bridging, double contour of sellar floor, irregularity at posterior of dorsum sella, pyramidal shape of dorsum sella. In previous studies, sella morphology was evaluated on lateral cephalometric radiography and CBCT images [17, 26]. As far as we have seen, there is no study examining the relationship between Camp’s classification and Axelsson’s classification. The aim of this study is to investigate the prevalence of the basic morphological classification and Axelsson classification by mean age and gender in the South-Eastern Anatolian population, and to evaluate the relationship between the two classifications.

The present study was approved by the Clinical Research Ethics Committee of the …………. University (Approval No: 2020/388).

In this study, all facial CBCT images of the patients who applied to the Dentomaxillofacial Radiology Department of ………….. University for various reasons were retrospectively analyzed. Patients with evidence of bone disease, congenital disorder, trauma history, whichever tumor or malignancy history, undergoing surgery and images containing artifacts were excluded from the study. Full head CBCT images of 1000 patients (535 men, 465 women) aged 6–91 years were retrospectively analyzed with Planmeca ProMax 3D Mid (Helsinki, Finland) device and Planmeca Romexis version 3.2.0 software (Helsinki, Finland). Images with a field of view (FOV) range of 16x16 cm, a voxel resolution of 0.4 mm³ and a slice thickness of 1 mm were used. All CBCT scans were performed according to a standard screening protocol. The images were evaluated on multiplanar (axial, sagittal and coronal) sections by two dentomaxillofacial radiologists with the first observer 2 (M.E.D.) and the second observer 9 (E.D.Y.) years of experience. The evaluations on 200 images (20% of all images) were checked again after 2 weeks for intra- and inter-observer agreement. The morphological types of sella turcica were examined as follows: the basic morphological types were circular type, oval type, flattened type (Fig. 1); according to Axelsson classification, normal sella turcica, oblique anterior wall, double contour of sellar floor, irregularity (notching) in the posterior part of the sella, sella turcica bridging, pyramidal shape of the dorsum sella (Fig. 2).

Statistical analysis of the study was performed with SPSS program version 20.0 (Armonk, NY, IBM). Kolmogorov Smirnov test was used to examine the suitability of of the available data for normal distribution. Relationships between categorical variables were calculated with the χ² test. Significance level was accepted as p < 0.05.

The intra- and inter-observer reliability coefficient was found to be excellent for all assessments (0.91 and 0.88, respectively), and the examinations of the first observer were taken as basis. 1000 CBCT images were evaluated according to two classifications. 535 of the cases were male and 465 were female. The mean age of all patients was 42.71 ± 18.16. The mean age of men was 42.85 ± 18.46 and 42.55 ± 17.83 in women. According to the basic morphological classification; oval type 48%, flattened 34.7%, circular 17.3% were detected at the rate. The distribution of basic morphological sella by gender is represented in Table 1. When the basic classification was examined by gender, the most prevalent type was oval in both genders. While flattened and oval type sella were more common in men than in women, circular sella was more common in women (p < 0.001). According to Axelsson classification, the most common morphological type was normal sella turcica with 53.2%. Other morphological types were as follows, respectively: irregularity in the posterior part of the dorsum sella 40.9%, sella turcica bridging 2%, dorsum sella pyramidal shape 1.7%, oblique anterior wall 1.2%, double contour of floor 1%. No significant relationship was found between Axelsson classification and gender. The relationship between Axelsson classification and basic morphological classification was investigated and shown in Table 2. Mostly, irregularity in the posterior part of the dorsum sella was detected with flattened shaped sella. Normal sella was most seen with oval shaped sella (p < 0.001).

Table 1

Distribution of the basic morphological classification of sella turcica by gender.
		Basic Morphological Classification			Total N (%)	P
		Circuler N (%)	Oval N (%)	Flattened N (%)
Gender	Male	75 (14.02)	250 (46.72)	210 (39.25)	535 (53.5)	0.001*
	Female	98 (21.08)	230 (49.46)	137 (29.46)	465 (46.5)
Total		173 (17.3)	480 (48.0)	347 (34.7)	1000 (100.0)
*p < 0.05

Table 2

Coexistence rates of basic morphological classification and Axelsson classification.
Basic Morphological Classification	Axelsson Classification						Total N (%)	P
Basic Morphological Classification	Normal sella turcica N (%)	Oblique anterior wall N (%)	Double contour of sellar floor N (%)	Irregularity (notching) in posterior part of sella N (%)	Sella turcica bridging N (%)	Pyramidal shape of dorsum sella N (%)	Total N (%)	P
Circular	79 (7.9)	0 (0.0)	4 (0.4)	84 (8.4)	0 (0.0)	6 (0.6)	173 (17.3)	0.001*
Oval	320 (32.0)	10 (1.0)	4 (0.4)	118 (11.8)	19 (1.9)	9 (0.9)	480 (48.0)
Flattened	133 (13.3)	2 (0.2)	2 (0.2)	207 (20.7)	1 (0.1)	2 (0.2)	347 (34.7)
Total	532 (53.2)	12 (1.2)	10 (1.0))	409 (40.9)	20 (2.0)	17 (1.7)	1000 (100)
*P < 0.05

In the literature, the basic morphological structure was examined in the sella studies with CBCT, but the relationship between Axelsson classification and basic morphological classification has not been evaluated. In this study, the relationship between these two classifications was examined with CBCT and a statistically significant relationship was found between them. Irregularity in the posterior part of the dorsum sella was detected in 20.7% of flattened sella cases. Normal sella was detected in 32% of the cases with oval shaped sella.

Various researchers have reported that some anomalies and syndromes increase the incidence of sella turcica morphological variations. However, it is not correct to associate every case with an anomaly because there are variations in healthy individuals [ 4, 12, 14, 15, 19]. In previous studies, there are different evaluations about the morphology of sella turcica. Zagga et al. [28], in their study on 228 lateral cephalometric radiographs of healthy Nigerian individuals, examined the sella turcica in three groups as circular, oval and flat; reported that the oval type was seen in 83%, the circular type in 11% and the flat type in 6% of the images. In the study of Islam et al. [9] conducted with CT in Bangladesh population, sella type was found as 48.1% oval, 28.3% flat, 23.4% circular. In the CBCT study of Yasa et al. [26], circular 69.5%, flattened 16.4%, oval 14.1% sella shape was observed. In Yalcin's study on individuals with cleft palate using CBCT, flattened was found to be the most common with 38.2% [25]. In the present study, the oval sella shape was observed at a rate of 48%, consistent with the study of Islam et al. [9]. Unlike other studies, oval and flattened types were more common in males, and circular type was more common in females. It can be thought that this difference may be due to race, population difference, the imaging method used and the number of individuals included in the study.

Axelsson et al. [5] made a new morphological classification of sella for the first time in 2004, and reported the normal sella rate as 65% in women and 71% in men. In the studies performed on lateral cephalometric films, normal sella was determined at the rate of 76.15%, 66.1%, 66.8%, 46.5%, 39% [ 1, 17, 20, 27, 23]. There is only one study investigating the morphology of the sella on CT, in which normal sella turcica was found as 69.2%. [9]. There are few studies with CBCT in the literature. In these studies, normal sella was seen in 69.1% and 49.8% [10, 25]. Consistent with other studies, the most common type in this study was normal sella. No significant difference was found in normal sella turcica by gender. In the studies conducted with cephalometry and CBCT in the literature, irregularity in the posterior of the dorsum sella was observed at rates of 16.7%, 16.2%, 12.1%, 8.6%, 7%, 5.38%, 3% [1, 10, 17, 20, 23, 25, 27]. Unlike these studies, this rate was found to be 40.9% in the current study, and no significant difference was observed according to gender. This may be due to the higher average age and the higher number of scanned images in this study.

Leonardi et al. [14] reported that sella turcica bridging is more likely to be seen in individuals with dental anomalies. Previous studies on cephalometric radiographs, sella bridging was found to be 8%, 7.5%, 1.1%, 0.76% [1, 17, 20, 27]. The pyramidal shape of the dorsum sella was found to be 15.5%, 8.5%, 7.7%, 6.5%, 4.4%, 3.8%, 3.0%, 2.6% [1, 9, 10, 17, 20, 23, 25, 27]. In this research, the pyramidal shape of the dorsum sella was found in 1.7%. In various studies in the literature, the oblique anterior wall was observed as 29%, 15.9%, 14.4%, 10.3%, 8.9%, 4%, 3.8% [ 1, 17, 20, 23, 25, 27, 28]. In the study conducted by Axelsson et al. [5], in Norwegian individuals aged 6–21 years, oblique anterior wall was the most common anatomic variation in males; bridging and irregularity in the posterior part of the dorsum sella were more common in females. In this research, no significant difference was found in the distribution by gender. In previous studies, double contour of sellar floor was detected as 14.6%, 8.46%, 8.4%, 6.6%, 5.5%, 3.5% [1, 9, 17, 20, 23, 27]. The different rates in this study compared to others may be due to ethnic origin, population and imaging device differences. Another reason why we found a lower rate than studies on cephalometric films may be that superpositions in the CBCT have been eliminated. In most of the cases with flattened sella, irregularity in the posterior of the dorsum sella was detected. This may be due to bone resorption based on the reduction in the pituitary gland size. Normal sella type was observed in most of the patients with oval-shaped sella. This may be due to the pituitary gland is of normal size.

The limitation of this study was that the pituitary gland was not examined because the soft tissues could not be adequately visualized in CBCT. It is recommended to conduct multicenter studies including magnetic resonance imaging technique in future studies.

The results of this study indicated a higher rate of normal sella morphology on CBCT compared to studies performed in a wide age range. Oval sella was mostly observed with normal sella, and the flattened sella was mostly observed with irregularity (notching) in the posterior part of the dorsum sella. Knowledge of the sella morphology can be important for accurate diagnosis and appropriate treatment planning for endoscopic transsphenoidal surgery. The morphological structure and variations of sella turcica can be evaluated effectively on CBCT.

Funding The authors received no specific funding for this work.

Conflict of interest The authors declare that they have no conflict of interest.

Ethical approval This retrospective study was approved by the Clinical Research Ethics Committee of the Gaziantep University (Approval No: 2020/388), and conducted in the Dentomaxillofacial Radiology Department of Gaziantep University, Faculty of Dentistry.

Informed consent Formal consent is not required.

Author contributions EDY: protocol/project development, data collection or management, data analysis, manuscript writing/editing. MED: data analysis, data collection or management, manuscript writing/editing. All authors reviewed the manuscript.

Alkofide, EA (2008) Sella turcica morphology and dimensions in cleft subjects. Cleft Palate Craniofac J 45(6): 647–653.
Amar AP, Weiss MH (2003) Pituitary anatomy and physiology. Neurosurg Clin N Am 14(1): 11–23.
Andredaki M, Koumantanou A, Dorotheou D, Halazonetis DJ (2007) A cephalometric morphometric study of the sella turcica. Eur J Orthod 29(5): 449–456.
Axelsson S, Storhaug K, Kjaer I (2004) Post-natal size and morphology of the sella turcica in Williams syndrome. Eur J Orthod 26(6): 613–621.
Axelsson S, Storhaug K, Kjaer I (2004) Post-natal size and morphology of the sella turcica. Longitudinal cephalometric standards for Norwegians between 6 and 21 years of age. Eur J Orthod 26(6): 597–604.
Becktor JP, Einersen S, Kjaer I (2000) A sella turcica bridge in subjects with severe craniofacial deviations. Eur J Orthod 22(1): 69–74.
Camp JD (1924) Normal and pathological anatomy of the sella turcica as revealed by roentgenograms. Am J Roentgenol 12: 143–56.
De Vos W, Casselman J, Swennen G (2009) Cone-beam computerized tomography (CBCT) imaging of the oral and maxillofacial region: a systematic review of the literature. Int J Oral Maxillofac Surg 38(6): 609–625.
Islam M, Alam MK, Yusof A, Kato I, Honda Y, Kubo K et al (2017) 3D CT study of morphological shape and size of sella turcica in Bangladeshi population. J Hard Tissue Biol 26(1): 1–6.
Isman O, Kayar S, Aktan AM (2020) Cone beam computed tomography evaluation of variations in the sella turcica in a Turkish population. Folia morphol 79(1): 46–50.
Iwanaga S, Shimoura H, Shimizu M, Numaguchi Y (1998) Gorlin syndrome: unusual manifestations in the sella turcica and the sphenoidal sinus. Am J Neuroradiol 19(5): 956–958.
Jones RM, Faqir A, Millett DT, Moos KF, McHugh S (2005) Bridging and dimensions of sella turcica in subjects treated by surgical-orthodontic means or orthodontics only. Angle Orthod 75(5): 714–718.
Kjaer I, Hansen N, Becktor KB, Birkebaek N, Balslev T (2001) Craniofacial morphology, dentition, and skeletal maturity in four siblings with Seckel syndrome. Cleft Palate Craniofac J 38(6): 645–651.
Leonardi R, Barbato E, Vichi M, Caltabiano M (2006) A sella turcica bridge in subjects with dental anomalies. Eur J Orthod 28(6): 580–585.
Leonardi R, Farella M, Cobourne MT (2011) An association between sella turcica bridging and dental transposition. Eur J Orthod 33(4): p. 461–465.
Ludlow JB, Ivanovic M (2008) Comparative dosimetry of dental CBCT devices and 64-slice CT for oral and maxillofacial radiology. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 106(1): 106–114.
Magat G, Sener SO (2018) Morphometric analysis of the sella turcica in Turkish individuals with different dentofacial skeletal patterns. Folia morphol 77(3): 543–550.
Mutluer S (2006) Sella turcica. Childs Nerv Syst 22(4): 333.
Mølsted K, Boers M, Kjaer I (2010) The morphology of the sella turcica in velocardiofacial syndrome suggests involvement of a neural crest developmental field. Am J Med Genet A 152(6): 1450–1457.
Nagaraj T, Shruthi R, James L, Keerthi I, Balraj L, Goswami RD (2015) The size and morphology of sella turcica: A lateral cephalometric study. Journal of Medicine, Radiology, Pathology and Surgery 1(3): 3–7.
Rennert J, Doerfler A (2007) Imaging of sellar and parasellar lesions. Clin Neurol Neurosurg 109(2): 111–124.
Russell BG, Kjær I (1999) Postnatal structure of the sella turcica in Down syndrome. Am J Med Genet 87(2): 183–188.
Shah MA, Bashir U, Ilyas T (2011)The shape and size of the sella turcica in skeletal class I, II & III in patients presenting at Islamic International Dental Hospital, Islamabad. Pakistan oral & dental journal 31(1): 102–108
Tekiner H, Acer N, Kelestimur F (2015) Sella turcica: an anatomical, endocrinological, and historical perspective. Pituitary 18(4): 575–578.
Yalcin ED (2020) Morphometric analysis of sella turcica using cone-beam computed tomography in patients with cleft lip and palate. J Craniofac Surg 31(1): 306–309.
Yasa Y, Ocak A, Bayrakdar IS, Duman SB, Gumussoy I (2017) Morphometric analysis of sella turcica using cone beam computed tomography. J Craniofac Surg 28(1): 70–74.
Yassir YA, Nahidh M, Yousif HA (2010) Size and morphology of sella turcica in Iraqi adults. Mustansiria Dent J 7(1): 23–30.
Zagga A, Ahmed H, Tadros AA, Saidu SA (2008) Description of the normal variants of the anatomical shapes of the sella turcica using plain radiographs: experience from Sokoto, Northwestern Nigeria. Ann Afr Med 2008. 7(2): 77–81.

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Evaluation of Sella Turcica Types Using Cone-beam Computed Tomography

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