SOP/Guidlines for Animal MR Imaging Studies
Effective date: June 1st, 2008
Update date: August 12, 2008
I. Purpose: The guidelines provide investigators with general information on animal imaging studies using MRI and proper usage of MRI instrument in the BRIC- Small Animal Imaging Facility (SAIF).
II. Responsibilities and Scope:
- All investigators involved in performing MRI/MRS animal studies must familiarize themselves with this SOP.
- It is the responsibility of the Principle Investigators to provide the SAIF with the following documents prior to the first imaging session:
- SAIF Project Proposal Form
- Approved Animal Protocol (including any amendments)
- Grant Account Number for billing purposes
- It is the responsibility of the investigators to care for animals in a humane way in accordance with IACUC protocols.
- It is the responsibility of the PIs to follow the SOP for the Animal Transportation Regulations established by UNC IACUC.
- It is the responsibility of the PIs to arrive at the imaging facility preferably before the scheduled time. In the event that a user is late or does not show up, he/she will still be charged for the scheduled time unless cancellation is informed 3 days prior to the scheduled studies.
- When reserving imaging time slots, researchers must include at least 10 minutes in their imaging session for cleaning the instrument and countertop.
- It is the responsibility of the PIs to inform SAIF staffs any specific requests for imaging, including animal anesthesia, specific positioning, and imaging quality.
III. General Procedures:
- Prior to the imaging study, the investigator must sign up for a time slot to use the MRI instrument.
- The investigator needs to bring the animals to the SAIF MRI facility before or at the scheduled time.
- Except specifically described in the PI’s protocol, all imaging animals will be anesthetized using isoflurane gas. (Please inform SAIF staffs if you wish to use different anesthesia method.) Immediately prior to MR imaging, the animal will be placed in an induction chamber with a short 3-5% Isoflurane/ medical-air mixture. All excess Isoflurane will be scavenged by placing an activated carbon canister on the exhaust port of the induction chamber.
- Once general anesthesia is induced, the gas flow will be turned off, the animal will be removed from the induction chamber, and attached securely to a nose cone. The anesthesia supply line and scavenging canister will be removed from the induction chamber and attached to the nose cone and the flow of anesthesia resumed.
- Any procedures specific to the protocol (such as tail vein catheter placement, or other surgical procedures) should be performed at this stage while maintaining anesthesia.
- For prolonged procedures core body temperature should be maintained using either a heat lamp or heating pad.
- The animal will then be placed on an animal cradle and securely attached to the nose cone used for MRI scanning. The isoflurane anesthesia machine in the MRI scanning room will be connected to the nose cone to maintain anesthesia with 1.5-2.5% isoflurane/medical-air mixture.
- Vital signs monitoring probes/electrodes, such as breathing probe, temperature probe, and ECG probes should be attached to the animal at this time. The leads for the probe should be tightly taped to the animal, and secured to the cradle to avoid dislodging during the positioning of the animal. Attach the probes to the controller box unit and verify that all connections are secured and they are functioning properly. Adjust if necessary.
- Position the animal or targeted imaging part in the RF coil such that the region of interest is centered in the homogeneous region of the coil.
- Position the coil in the magnet and insert the warm air hose inside the bore such that the warm air flows over the animal.
- Animal body temperature must be monitored and maintained at 37°C (rodents) while the animal is in the magnet. Headed air flow or circulating water must be employed to maintain the body temperature. Verifying the animal temperature control system is functioning properly.
- Perform a short localizing scan to adjust the animal position so that the ROI is within the scan FOV.
- MR system will be then calibrated, including the matching & tuning of the coils, system shimming & frequency/transmit adjustment. Several MR parameters, such as PVM-REFATT, need to be checked to ensure proper functions of the coils.
- If there is suspected animal motion artifact, the short localizing scan can be used to check motion related artifacts. If the motion artifacts are too severe to provide high quality of images, the animal needs to be repositioned and secured. If all of the above procedure can not reduce motion to an acceptable level for a reasonable period of time, the animal needs to be returned to the cage.
- Set up imaging protocol, perform MRI/MRS acquisition. Vital signs of the animals need to be monitored during the period of data acquisition.
- Remove all electrodes/probes and tape from the animal. Turn off the anesthesia, remove the animal from the nose cone and return the animal to its cage.
- Wipe all surfaces in the coil, animal cradle, and nose cone that come into contact with the animal with diluted Roccal (provided in each imaging room). Also wipe down any vital signs monitoring probes that came into contact with the animal. Remove all tape and tape residue from all equipment used in the study.
- Remove the coil from the magnet, and put it back to the proper storage location.
- Monitor the animal’s recovery from anesthesia. Keep the animal warm during recovery procedure. Once the animals recover from anesthesia, call the investigator to take the animals back to the animal facility. Animals are not allowed to stay for more than 12 hours in the imaging facility.
- Make sure the gas and isoflurane machine is turned off.
VI. Safety Considerations:
- Everyone that has not read and signed up the MRI Magnet Safety Registration Form should not enter the MRI scanner room. The SAIF staffs should always remind users to be aware of the strong magnet field of the scanner.
- Reminder: Drinking, eating and open-toe shoes are not allowed under any circumstances in all of SAIF. Anyone dealing with animals should wear lab coat and gloves during any procedures.