Practical Guidance for Optimizing Quality of Computed Tomography Studies in Zoological Species
Use of cross-sectional imaging, particularly computed tomography (CT), is on the rise in clinical zoological medicine. Advanced imaging technologies such as CT necessitate a degree of technical knowledge and planning that is more complex than radiography or conventional ultrasonography. This is true for all domestic animals, but the more complicated logistics of zoological patient handling demand maximal preparation, coordination, efficiency, and expertise. Whether scans are performed in-house at a zoo or externally at a referral center or human hospital, practical knowledge of CT acquisition parameters by zoo and aquarium clinicians can greatly enhance the diagnostic quality of a study. Optimal positioning is critical, based on the species, anatomical region of interest, disease process, and anesthetic plan. Choices regarding slice thickness, scan field-of-view, exposure settings, reconstruction algorithms, and order of body region assessment all affect image interpretation. Photon starvation considerations with large animals can often be overcome by adjusting scan parameters and/or the geometric alignment of limbs. Timing of image acquisition following contrast administration, choice of contrast media (concentrations, pharmacology), and comprehension of the utility and limitations of contrast usage are all part of careful planning. Recognition and prevention of artifacts are critical in deciding whether scans need to be repeated or can be corrected. Application of CT-guided sampling may also impact scan considerations. Generation of multiplanar and minimum/maximum intensity projections after a scan can improve lesion identification. Practical guidelines for clinical zoo veterinarians detailing planning and execution of CT studies are presented.