Senem Turan Ozdemir

Facial asymmetry in young healthy subjects evaluated by statistical shape analysis

Statistical shape analysis, a relatively a new method for biological research, compares body forms by using specific landmarks determined by anatomical prominences. In this study, we aimed to identify normal facial asymmetry between the right and the left sides of the face. Facial landmark data were collected from two‐dimensional digital images of 321 young healthy subjects (150 males and 171 females). These data were analysed using Euclidean distance matrix analysis. The number of significantly asymmetric linear distances between the two halves of the face was greater in females than in males. We found that the left side of the face was most commonly dominant in both males and females. Such data may be useful in establishing a database for future similar studies.

Statistical Shape Analysis of Differences in the Shape of the Corpus Callosum Between Genders

Sexual dimorphic characteristics, which play an important role in human evolution studies and biological research, can be studied morphologically and metrically. Geometric morphometrics allows a better assessment of morphological characteristics. Statistical shape analysis has a long history in neuroanatomical and other research. The aim of this study was to identify shape differences of the corpus callosum between genders. Landmark coordinate data were collected from two‐dimensional magnetic resonance imaging scans of 93 homogeneously aged patients, 45 men and 48 women. These data were analyzed using Euclidean distance matrix analysis and thin plate spline analysis. The general shape variability of the corpus callosum of men was greater than that of women (men, 0.134; women, 0.097). We found no significant difference between sexes in the general shape of the corpus callosum, but we did find significant differences in the distances between some landmarks. Deformation of the corpus callosum between men to women was mainly detected in the posterior of the corpus callosum. These results serve as a reference for future studies on shape alterations of the corpus callosum associated with certain conditions. Anat Rec, 2007.

Detecting the Shape Differences of the Corpus Callosum in Behçet's Disease by Statistical Shape Analysis

The aim of this study was to assess the shape differences of the corpus callosum (CC) in patients with Behçets disease using statistical shape analysis (SSA). Additionally, an attempt was made to investigate the changes in CC size according to disease duration. Twenty‐five adults with clinically diagnosed Behçets disease and 25 age‐ and gender‐matched controls were examined by high‐resolution structural magnetic resonance imaging. The data obtained from the coordinate of landmarks were analyzed with Euclidean distance matrix analysis and a thin‐plate spline analysis. SSA and growth curve models were performed to investigate group differences and to fit the curves. A significant difference was determined between CC shape of Behçet patients and controls (P = 0.006). Based on the analysis, a decrease occurred in the CC size of the Behçet patients as the duration of disease increased. Maximum deformations were determined in the landmarks of interior notch of the splenium, inferior tip of the splenium, posterior‐most point of the CC, and topmost point of the CC. Similarly, the landmark of anterior‐most point of the CC was identified as having the minimum deformation. Behçet patients had significantly different CC shapes from control subjects. The results suggest that SSA is a promising tool for distinguishing Behçet patients from normal subjects, and that it can give useful information to assist clinicians. Additionally, SSA might be applied to detect shape differences in anatomical structures that are affected by a broad range of neurological diseases. Anat Rec, 2011.

Statistical shape analysis of the rat hippocampus in epilepsy

In this study, we aimed to (1) propose landmarks for the hippocampus in a rat brain using an experimental study and (2) investigate hippocampus shape changes in a rat brain with epilepsy using the statistical shape analysis method. We have used the statistical shape analysis method to illustrate hippocampal shape deformation due to epilepsy. Statistical shape analysis is of increasing interest to the neuroimaging community because of its potential for locating morphological changes. Nineteen rat brains (ten healthy and nine epileptic) with hematoxylin and eosin images of the hippocampus were used. The results strongly indicated that the normalized hippocampal shape of the epileptic group was different from the nonepileptic group; deformation was seen most significantly in the medial regions of the cornu ammonis (CA1 and CA3) of the hippocampus. In conclusion, our landmark-based methodology detected regional differences in the hippocampus in epilepsy. This study may serve as an initial reference for future studies on shape alteration of the hippocampus associated with certain medical conditions.

Shape analysis of the corpus callosum and cerebellum in female MS patients with different clinical phenotypes.

The aim of this study was to investigate the shape differences in the corpus callosum (CC) and cerebellum of female relapsing‐remitting multiple sclerosis (RRMS) and secondary progressive multiple sclerosis (SPMS) patients compared with healthy controls. This study was conducted using the magnetic resonance imaging scans of 15 control subjects, 26 RRMS, and 14 SPMS patients. The data obtained from the landmark coordinates were analyzed with statistical shape analysis. The landmarks that were chosen to determine the shape differences of the CC and cerebellum have been identified and used in previous studies. In addition to these landmarks, constructed landmarks were determined and used to assess regional shape differences better. The shapes of the CC and cerebellum showed statistically significant differences from the controls when compared with both the RRMS and SPMS patients. It was found that the deformation observed from controls to SPMS was greater than the deformation from controls to RRMS, both for the CC and cerebellum. In conclusion, this study revealed CC and cerebellar shape change in RRMS and SPMS, and showed that deformations both in CC and cerebellum advances with the disease progression. Anat Rec, 2012.

The Concept of Anthropometric Facial Asymmetry

Facial asymmetry is a common finding in healthy subjects and in esthetically pleasing faces. It is believed that normal craniofacial skeletons have some degree of asymmetry which is compatible with normal dental occlusion, and mild facial asymmetry is often disregarded by clinicians. In parallel with increasing demand for facial aesthetics and recent advances in facial aesthetic surgery, patients have become more sensitive to facial asymmetry which may occur after the operation. In this context, objective evaluation of facial asymmetry by extended facial analysis before and after the operation has gained importance. Facial asymmetry analysis can be performed as objective and/or subjective. Soft tissues of the face can be evaluated by subjective analysis; however, skeletal asymmetries compensated by the overlying soft tissue may not be recognized most of the time. Objective assessment of the asymmetry degree of both soft and hard tissues of the face before facial operations, aesthetic and orthodontic procedures in particular, will allow a more accurate analysis of the treatment results. Anthropometric measurement is one of the methods used for the quantitative analysis of facial asymmetry. Although anthropological studies on face have been extensively addressed in the literature, anthropologists have rarely examined facial asymmetry. The concept of facial asymmetry and anthropometric measurement of facial asymmetry will be reviewed in this chapter.