MRI Anatomy of the Coelomic Cavity of the European Pond Turtle

Abstract

In turtles, most internal organs lie deep within the coelomic cavity and are covered by the rigid shell, which makes clinical assessment difficult. MRI can provide valuable information, but detailed descriptions of normal MRI anatomy in the European pond turtle (Emys orbicularis) are limited. To document how the non-respiratory coelomic organs of adult female Emys orbicularis appear on MRI and where they are located within the coelomic cavity. Ten adult females were examined using a 3-Tesla MRI scanner with T1- and T2-weighted transverse, sagittal, and dorsal sequences. Organs were identified based on their signal characteristics and anatomic position, and findings were compared with published anatomical studies in chelonians. MRI provided clear visualisation of the heart, major vessels, liver, gallbladder, gastrointestinal tract, spleen, kidneys, urinary bladder and reproductive tissues. All ventricular components including the cavum pulmonale, cavum venosum, cavum arteriosum, muscular ridge, and interventricular canal were consistently identified. Two separate hepatic veins (right and left) drained into the sinus venosus, which differs from patterns reported in several other turtle species. The right and left lateral abdominal veins joined near the midline to form a common vessel before entering the left hepatic lobe. The spleen was positioned on the right side of the coelomic cavity, ventral to the lung. The pancreas could not be distinguished due to similar signal intensity to the liver. The arrangement of the jejunum and ileum showed notable differences compared with other freshwater and marine turtles. This study provides the first clear MRI guide to the non-respiratory coelomic organs in female Emys orbicularis. These observations can help veterinarians interpret routine MRI exams and better identify disorders involving the gut, reproductive tract, vessels and urinary system. Studies that include contrast media or anatomical dissection are still needed to fully define the vascular pattern and the pancreas.