Diagnostic Application of Multirow Computed Tomography of the Hip Joint of Japanese Quails

December/2015 Approved: February/2016 ABSTRACT The morphological assessment of selected parts of the hindlimb of Japanese quails (Temminck & Schlegel, 1849), with particular emphasis on hip joint structures, was performed, using a 128-row scanner (GE Optima Aquilion, Toshiba, Japan). Eight dead 3-month-old Japanese quails were evaluated. During intravital examination of those birds, no hindlimb abnormalities or locomotion disorders were detected. Bird body, which hip joints and other structures of hindlimbs were studied, was examined in posterioranterior position. The following hip joint structures, on both sides, were assessed in this study: hip joint gap width, acetabulum width, femoral head diameter, and femoral shaft width. The applied imaging method allowed accurate assessment of the selected structures. There was low variability between left and right hindlimbs and among individuals. Modern imaging techniques, such as multirow computed tomography (MCT) allows quick intravital assessment of normal and pathological structures of poultry


INTRODUCTION
Diagnostic imaging is more frequently used for the detection of pathologies related to the passive part of the locomotor system in poultry (Charuta et al., 2011;Charuta et al., 2012). Modern techniques, such as magnetic resonance imaging (MRI) or multirow computed tomography (MCT), allow quick intravital assessment of specific body structures, including bones and joints. Diagnostic imaging is a rapidly developing field in human and veterinary medicines (Chang et al., 2014;, Aguado et al., 2015). It is also used for scientific research on the growth and development of organisms (Li et al., 2015), as well as on different species of poultry (Andrássy-Baka et al., 2003;Locsmándi et al., 2004;Romvári et al., 2004). Multirow computed tomography scanners (MCT) and magnetic resonance imaging (MRI) have been significantly improved, and today enable the diagnosis of various types of diseases. The influence of these diseases on locomotion disorders of poultry have been studied using optical 3D techniques (Caplen et al., 2012).
The Japanese quail has been used as animal model in many areas of developmental biology studies. Some authors suggest the possibility of using this model also in research on human aging and diseases (Huss et al., 2008). The assumption of this study is that MCT could be used as a method to diagnose abnormalities in the hip joint structures of Japanese quails, and to examine the joints of other species of breeding poultry. The early, intravital diagnosis of pathologies allows selecting individuals with good genetic potential for breeding. The aims of this study were to perform the examination and morphological evaluation of hip joints of Japanese quails using advanced imaging techniques.

Diagnostic Application of Multirow Computed Tomography of the Hip Joint of Japanese Quails (Coturnix Japonica)
Closer examination of the animal gives a more accurate diagnosis, and therefore, allow for more accurate treatments. Previously detected changes in individual subjects may prevent them in other animals, consequently shortening suffering and recovery times.

MATERIAL AND METHODS
Eight (five males and three females) dead 3-monthsold Japanese quails were studied. The birds selected for post mortem examination were culls of the flock of the Department of Genetics and Animal Breeding, Faculty of Animal Sciences, Warsaw University of Life Sciences (SGGW), Poland. Birds were reared according to the conditions recommended for this species, and fed ad libitum a diet containing 2600 kcal energy and 21.5% crude protein. Preliminary clinical examination of those birds and their locomotor system did not reveal any abnormalities.
Imaging examination was performed using a 128row MCT scanner (GE Optima Aquilion, Toshiba, Japan). Birds were placed in posterioranterior position in sealed airtight containers. Scanning parameters were: voltage of 120kV, time of exposure of 1.5s, exposure of 7mAs, current of 150mA, and slice thickness of 0.63.
Pixel size in subsequent image sequences was dependent on the size of the measured object. Therefore, pixel size was equal to 0.15 mm for the smallest object and 0.20 mm for the largest. It was decided to dispense with a fixed pixel size to fully exploit the field of the matrix recording, which size was 512x512 pixels. After the MCT images were obtained, the hindlimb was described with particular emphasis on the hip joint.
The VolView3 software was used to perform the following measurements on both hindlimbs (L and R): acetabulum width (AW), hip joint gap width (JGW), femoral head diameter together with trochanter (FS), and femoral shaft width (FW), as shown in Figure 1. Statistical analysis of the evaluated hip joint parameters was performed using the software IBM SPSS Statistics 21.0. The obtained values were statistically described. Data were analysed for normality by Kolmogorow-Smirnov test, with Lilliefors modification. Pearson's correlation analysis was performed for specific characteristics of the analysed parameters.

RESULTS
Results of this study show a slight, although not statistically significant, variation of analysed characteristics between left and right hindlimbs, as well as between individuals (Table 1). Difference between AW values (average of 0.07 mm), may be the result of error caused by inaccuracy in limbs arrangement and subsequently differences in their exposure on MCT images. The standard deviation of AW was ±0.18 mm. The largest standard deviation was 0.50 mm, recorded for right femoral shaft width (FWR) in females, which average was equal to 3.7 mm. A slight, but not statistically significant standard deviation (0.05 mm) was observed in the length of the femoral head on the left leg in males.
The average standard deviation value of most measurements is close to the average pixel size of the tomographic image. Therefore, it is expected that decreasing pixel size will reduce the average standard deviation of the obtained results.
Among the evaluated parameters, only FSR (p= 0.001) did not present normal distribution.
Pearson's correlation coefficients calculated for selected hip joint parameters are shown in Table 2. A statistically significant correlation of 0.707 (p=0.05) was observed only between JGWR and JGWL. In addition, despite not statistically significant (p=0.07), a clear correlation was observed between acetabulum and hip joint gap width on the left hindlimb.

DISCUSSION
Proper formation of the skeleton in domestic poultry is essential for production and breeding. Therefore, extensive research on the quality of the skeleton has been carried out, particularly on skeletal problems in the hindlimb, which supports the weight of the whole body (Fan et al., 2011;Charuta et al., 2013). In order to function normally, the anatomical structure of the limbs of breeding birds needs to be correct. However, in intensive livestock production, limb deformation and sometimes even fractures are recorded (Cooper et al., 2008). Reilly (2000), analyzed the involvement of particular sections Murawska D, Szlufik K, Bakoń L, Gruszczyńska J, Grzegrzółka B, Nowicki MV

Diagnostic Application of Multirow Computed Tomography of the Hip Joint of Japanese Quails (Coturnix Japonica)
of the lower limbs in the locomotion of Japanese quails, but did not provide a detailed morphological analysis of the joints. Abourachid et al. (2011) used 3D technology to analyze locomotion in quails. In scientific publications, there is no information on the diagnosis of the pathology of the hindlimb joints of quails. It seems that undertaking such research would be a valuable contribution for the knowledge in this field.
The current breeding, rearing and genetic selection practices of poultry are aimed at increasing growth rate. The progeny of poultry with excellent production parameters in breeding programs often present health and skeletal problems, including diseases of the joints, which etiology is rarely elucidated. High body weight and growth imbalance between the muscle mass and bones can cause deformities and fractures in poultry (Burs et al., 2008). The function of the hip joint and related diseases are well established in humans (Turmezei et al., 2014;Vahdati et al., 2014). Reduction of the hip joint gap may be the first symptom of osteoarthritis in this joint. The hip joint gap narrows when the cartilage that separates the soft tissues and bones of the joint degenerates. In humans, the knee and hip are the sites most often affected by osteoarthritis, and this disease is more frequent in women (Roemer et al., 2014).
Genetic factors, in addition to environmental factors, have a significant influence on the development of articular diseases. It should be noted that the selection for meat production within breeds and lines of mainly chickens and turkeys, but also of quails, has led to rapid growth and deposition of muscle tissue in the body, weight gain and high dressing percentage (Resende et al., 2005;Murawska, 2013). Despite the indubitable achievements in production performance, there were also negative consequences of the selection for weight gain, such the increasing incidence of metabolic disorders and diseases of the skeletal system (Ahmed & Soliman, 2013, Charuta et al., 2013. The so-called "weak legs", manifested by defective bones structure or dyschondroplasia, are examples of the "inadequacy" of the poultry's body to fast growth rates (Leeson & Summers, 1988;Ferket & Sell, 1989;Leach & Lilburn, 1992;Havenstein et al., 1994).  Only the birds in the flock with high genetic potential and resistance to diseases should be selected for reproduction. The examination of the hip joint gap after slaughter is not the best solution because it equally eliminates from the flock healthy and sick animals. Imaging diagnosis is a better solution because it allows to observe any changes in live animals, and do not require their sacrifice.
In humans, extensive studies conducted by a team led by Lequesne et al. (2004) showed the importance of the function played by the above-mentioned hip joint gap. Diseases of this joint were described in the publications of Goker et al. (2003), Daysal et al. (2007), and Sipola et al. (2011). Research on human diseases are the most advanced, and directly indicate the need for the for research on articular diseases in animals.
Multirow computed tomography (MCT) is a very good diagnostic tool for assessing the health of farmed poultry. Studies using this technology can serve as a model, and may be applied to assess the health status of other poultry species.