Fields EL, Robertson ID, Brown JC.
A major disadvantage of computed tomography for abdominal screening in dogs has been the need for general anesthesia to prevent motion artifacts. With multidetector helical CT, it is possible to decrease examination time, allowing patients to be scanned under sedation. It is also desirable to decrease tube loading to prolong x-ray tube life. To develop a protocol that will allow for examination of sedated patients with minimal image artifacts, milliamperage (mA) and helical pitch were varied, providing 16 experimental scan protocols. A standard clinical protocol was also tested, providing 17 protocols for evaluation. These protocols were tested, using a standard CT phantom, canine tissues in a water bath, and a canine cadaver. The cadaver images were scored semiquantitatively by three reviewers to determine the protocol with the best combination of speed and minimal image artifact. The optimized protocol was then applied to 27 sedated canine patients of three body weight categories. The images obtained were compared to the standard protocol by two reviewers for presence of motion, streak, and quantum mottle artifacts. There was significantly more streak artifact noted by one observer using the optimized study protocol, but no significant difference in any other category. Scanning under sedation was well tolerated in all patients, and sedated CT examination is a promising tool for screening abdominal disease in dogs.