What are the guidelines for using Magnetic Resonance Imaging (MRI) in zoo animals?

Guidelines for MRI Use in Zoo Animals

For zoo animals requiring MRI, light general anesthesia using inhalational agents like isofluorane or short-lived intravenous injectables such as propofol should be used for pharmacological restraint to minimize stress and ensure animal welfare. 1

Animal Preparation and Handling

• Light general anesthesia is preferred over physical restraint whenever possible to reduce stress and improve image quality 1
• When general anesthesia is not appropriate, sedation combined with gentle physical restraint should be used, following veterinary advice 1
• Animals should be thoroughly acclimatized to handling procedures before imaging to minimize stress responses 1
• Appropriate monitoring of vital signs during anesthesia is essential to prevent morbidity and mortality 1
• Animals should be kept warm during imaging procedures using warming devices such as aveable gels or warm air blowers 1

Technical Considerations

• Image acquisition should be conducted in 3D data acquisition mode for optimal results 1
• Attenuation correction should be performed using appropriate methods such as CT, MRI attenuation correction, or 511 keV-transmission scan 1
• For longitudinal studies, animals should be scanned on the same system using consistent procedures to minimize variations 1
• Metal artifacts can significantly impact image quality and quantification, requiring appropriate correction techniques 1
• MRI accuracy and artifact-free images are crucial for precise quantification, especially when imaging structures near bone 1

Special Considerations for Zoo Settings

• Custom-designed receiver coils may be necessary to accommodate various animal species and sizes 2
• Restrainers should be designed to minimize movement while ensuring animal comfort 2
• Habituation to the restrainer and scanner environment before the actual imaging session can reduce stress and improve image quality 2
• For small animals, clinical 3T MRI scanners can be adapted with appropriate coils and restraint systems 2

Potential Pitfalls and Limitations

• Small structures (<10 mm in diameter) may be difficult to visualize depending on the MRI system's spatial resolution 1
• Metal implants, dental work, or identification chips can cause significant artifacts in MRI images 1
• Movement artifacts can compromise image quality, emphasizing the importance of appropriate sedation or anesthesia 2
• The MRI environment presents unique safety challenges requiring specialized non-ferromagnetic equipment and monitoring devices 1

Welfare Considerations

• The wellbeing of zoo animals should be prioritized throughout the imaging process 3
• Recovery from anesthesia should be carefully monitored, with animals kept warm until fully recovered 1
• If animals need to be anesthetized more than once per day, they must be fully recovered, eating and drinking before being re-anesthetized 1
• The benefits of diagnostic information must be weighed against the risks of anesthesia and handling stress 3

By following these guidelines, veterinary professionals can optimize the use of MRI technology for zoo animals while minimizing risks and ensuring animal welfare.