Comparison between ultrasound images of the dog brain with and without the calvaria and its correlation with real anatomy

Abstract

Bones are believed to be an effective barrier to obtain sonographic images. In fact, the large difference between acoustic impedances of surfaces of the soft and bone tissues generates significant image artifacts. However, transmission of the ultrasound beam depends on bone thickness and structure. Therefore, the temporal bone has been used as an acoustic window to access the brain of adult patients with ultrasonography. The purpose of this study was to assess the brain of adult dogs using ultrasonography with and without bone interposition, compare the images, and correlate them with the brain anatomy. Ten mesaticephalic adult dogs were used, and the ultrasound examination was performed through the magnum orifice and on the temporal, lateral parietal, and frontal bones. A small craniotomy was performed in the frontal bone for examination without bone interposition. We were able to acquire images of the brain with bone interposition. However, resolution of these images was lower than the ones obtained by craniotomy. Important anatomical structures were identified. Regarding the correlation and the wide availability of ultrasound equipment, it was concluded that ultrasound can be used as a tool for monitoring expansive intracranial lesions or in intraoperative procedures.