Adrenal Glands of Chinchilla lanigera - Study of Anatomical Features with Computed Tomography and Magnetic Resonance Imaging

Abstract

Background: Since chinchilla (Chinchilla lanigera) is frequently used as a laboratory animal, satisfactory data about the imaging anatomical appearance of its adrenal glands, such as their anatomical location and closeness with other abdominal soft tissue and vessels, are important. The aim of this study to determine anatomical features of the chinchilla adrenal gland's using computed tomography and magnetic resonance imaging. Materials, Methods & Results: We used 12 chinchillas (6 males and 6 females), aged 18 months. The animals were in supine recumbency when contrast-enhanced computed tomography (CT) was performed. Transverse, sagittal and dorsal images of the adrenal glands were obtained with iodinated contrast medium, and 3D reconstruction of the obtained images was applied. The craniocaudal (CrCc - length), dorsoventral (DV - height) and lateromedial (LM - width) diameters were measured using an electronic calliper. Magnetic resonance imaging was performed, and coronal T1-weighted images were obtained. The transverse CT anatomical image at the level of the 3rd lumbar vertebra demonstrated the location of the both adrenal glands in accordance with the grey-white scale's variation. The right adrenal gland was hypo-attenuated and elliptic compared to the right kidney and in close contact to it and to the caudal vena cava. The left adrenal gland was oval and at a distance to the abdominal aorta. The dorsal MRI anatomical study of the chinchilla's abdominal organs at a distance of 10 mm from the spine and in a T1-weighted sequence showed that both adrenal glands were retroperitoneal organs. Discussion: Post-contrasted CT defined the topography of both glands. The right adrenal gland has an oval shape and is cranially situated to the left gland, whose shape is cylindrical and elongated. The LM diameter of the right gland is higher than that measured in the left gland. Both DV and CrCc diameters of the right gland are lower compared to those of the left gland. The right adrenal gland is in close contact to the caudal vena cava, the right kidney and the liver, and the left adrenal gland is in a distance to the abdominal aorta. The right adrenal gland was close to the caudal vena cava and the right kidney and medially to the left kidney. The successful comparative analysis of the images in 3D reconstruction and post-contrast CT in 2D allowed us to conclude that 3D reconstruction is suitable to obtain detailed information in a summary form regarding the closeness of the glands and their shape, mainly because the results are in a real time and highly comprehensive. Our data are in in agreement with previous findings about the advantages of 3D reconstruction. The research algorithm applied was based on the dorsal visualization of the glands in T1-weighted sequence, achieving a comprehensive and high-quality MRI imaging of the examined organs in chinchillas. Both adrenal glands were retroperitoneal organs and with low signal. The dorsal MRI anatomical study of the chinchilla's abdominal organs at a distance of 10 mm from the spine and in a T1-weighted sequence showed the whole profile of the right and left glands and the cranial position of the right gland to the left one, the close contact between the right gland and the kidney and the distance between the left gland and the left kidney. The MRI results are detailed and comprehensive for interpretation. In conclusion, the results of the present study are comprehensive, detailed and with high resolution. We present data for the anatomical relationships of the studied organs, their shape and macrometric parameters, concluding that the above mentioned modalities are very important tools for studying the chinchilla's adrenal glands to create a morphological base, which is necessary to investigate specific diseases