Computed tomography and cross-sectional anatomy of the brain in clinically normal dogs

To provide a detailed anatomic description of brain structures in clinically normal dogs by means of computed tomography (CT).

4 clinically normal adult German Shepherd Dogs weighing 30 to 35 kg.

Each dog was anesthetized and positioned in ventral recumbency for CT examination of the brain; transverse scans were completed at 2-mm intervals from the cribriform plate of the ethmoid bone to the cranial part of the atlas by use of a third-generation CT scanner. Contrast material was injected IV, and a second series of scans was completed. Images (with or without contrast) from all dogs were reviewed by use of a soft tissue setting (window width, 150 Hounsfield units; window level, 50 Hounsfield units). One of the dogs was euthanatized, and a 3.5% formaldehyde solution was perfused via the common carotid arteries. After fixation, the brain was embedded in gelatin and sectioned into 5-mm-thick transverse sections by use of a stainless-steel knife. Anatomic sections were photographed and compared with the corresponding CT views.

Most features of the brain that were identified on anatomic sections could be identified on the corresponding CT scans despite the low contrast between structures, particularly if adjacent bony and soft tissue structures were used as landmarks. Additional anatomic structures surrounding the brain were also identifiable on the CT images.

Images obtained in this study could be used as a guide for evaluation of CT images of the brain in dogs with brain diseases.