ECG-Gated Cardiac Multidetector CT Evaluation of the Normal Pulmonary Valve and Right Ventricular Outflow Tract in Dogs

With the advancement in imaging technology, ECG-gated cardiac multidetector computed tomography (MDCT) has emerged as a tool for the anatomic evaluation of the pulmonary valve and right ventricular outflow tract (RVOT) in human medicine. Currently, the evaluation of the pulmonary valve relies primarily on echocardiographic examination. However, the bi-dimensional nature of this technique and the location/orientation of the pulmonary valve in the thoracic cavity can pose challenges. In human medicine, ECG-gated MDCT distinguishes four main anatomic components of the pulmonary valve and RVOT: the pulmonary valve leaflets, the sinotubular junction, the anatomic ventriculo-arterial junction and the hemodynamic ventriculo-arterial junction. Hence, this study aimed to describe the computed tomographic findings of the normal RVOT and pulmonary cusps in a population of dogs. This is an anatomic prospective descriptive study. A total of 24 dogs underwent a complete echocardiographic examination and an ECG-gated MDCT to rule out pulmonary valve abnormalities. Multiplanar reconstruction of the pulmonary valve was obtained. Additionally, hearts from three dogs euthanized for reasons unrelated to the study were collected and their gross and histological findings were compared with the CT images. The ECG-gated MDCT provided good visualization of the pulmonary valve leaflets, the sinotubular junction, the anatomic ventriculo-arterial junction and the hemodynamic ventriculo-arterial junction. Notably, the short-axis view of the pulmonary valve anatomy resembled the 'Mercedes-Benz sign' characteristic of the aortic valve in all dogs. In conclusion, this study provides the first description of the CT anatomy of the RVOT in dogs without pulmonary valve and RVOT abnormalities.