With an estimated 30 BCH divisions and departments engaging in various lines of basic science and clinical research, the infrastructure needed to support, sustain, and monitor these diverse, multidisciplinary activities is being outstripped by the pace of these investigations and the advanced technologies that serve as their underpinning.
Nowhere has this been more evident than in small animal imaging where recent access to microPET and microCT imaging technology offered through the SAIL has not only generated enormous enthusiasm, it has revealed considerable demand for these imaging tools, which are increasingly viewed as indispensable to cutting edge research. With the establishment of the Small Animal Imaging Facility in 2006, it became quickly apparent that only a full complement of small animal imaging devices would address the dynamic imaging needs of the growing basic science BCH research community.
Kresge Lab Utilization Form:
The Kresge Lab Utilization form for imaging small animals (mice, rats) needs to be completed and a copy returned to both Karen Krueger and Pat Dunning prior to imaging for approval.
Kresge Lab Utilization Form
Surgical Request Form:
Large animal (rabbits, pigs, sheep) imaging needs to be scheduled using the surgical request form through Katie Mullen who will coordinate with Pat Dunning to schedule the study.
PET imaging studies will be performed using the Siemens Focus 120 high-resolution, small-animal PET scanner located in the Kresge Imaging Facility in ARCH. Each animal will be injected via tail vein with a bolus injection (less than 0.2 mL) of the radiopharmaceutical. The amount of radioactivity administered will be between 3.7 and 37 MBq (0.1 to 1.0 mCi). The activity in the syringe before and after the injection will be assayed in a dose calibrator to determine the actual amount of administered activity. Only trace amounts of the radiopharmaceuticals are delivered to the animals, and thus no toxic effects are anticipated. For 18F fluoro-deoxy-glucose (FDG) imaging, the animals may be fasted a minimum of 6 hours and up to 14 hours (overnight) prior to imaging to minimize uptake of FDG in soft tissue. Blood sampling (not more than 100 ?L) by lancing the tail vein also may be performed to evaluate blood glucose and/or insulin levels at the time of imaging.
Animals will be anesthetized to facilitate imaging. The animal will be anesthetized by inhalation of isoflurane (2-4%) through a nose cone for the duration of the imaging study. Exhaled anesthesia gas is trapped by a scavenging system. The animal will be visually monitored throughout the imaging procedure. Additional anesthetic will be administered if the respiration rate becomes rapid, the animal responds to a moderate toe pinch or the animal starts to move. A combination of Ketamine (60-70 mg/kg) and xylazine (5-10 mg/kg) may also be used during he preparation of the animal. If delayed imaging (e.g. at 2 or 24 hours) is necessary, the animal will be allowed to recover from anesthesia, returned to the cage between imaging sessions, and re-anesthetized before additional images are acquired.
Image acquisition will begin after an appropriate uptake period (0-60 minutes), which depends on the biokinetics of the specific radiotracer. Each animal will be positioned on the imaging table (head first, prone), and a heating pad will be placed beneath the animal in order to maintain an appropriate body temperature. Body temperature may be monitored during the study using a rectal probe. ECG electrodes will be applied if cardiac gating is required. Depending upon the field to be imaged, animal size, and radiopharmaceutical, each animal will be imaged for 15 to 60 minutes. After completion of imaging, animals will be held until they are no longer radioactive and are appropriate for routine cage housing. Typically, this will be no more than 10 half-lives of the radiopharmaceutical. Arrangements for housing will be made with ARCH and Radiation Safety. If animals are not to be returned to ARCH housing, they will be euthanized via CO2 inhalation (when age 14 days or greater) or decapitation (if less than 14 days of age).
MicroCAT imaging will be performed on the Siemens MicroCAT II scanner. This is a high-resolution (27 microns in standard mode and 15 microns in high-resolution mode) CT scanner designed specifically for imaging small animals such as mice and rats. The radiation detector is configurable such that, for mice, the transaxial field of view is 5.4 cm and the axial field of view is 8 cm, whereas for rats, the transaxial field of view is 8 cm and the axial field of view is 5.4 cm. A combination of Ketamine (60-70 mg/kg) and xylazine (5-10 mg/kg) may also be used during the preparation of the animals. Prior to imaging, the animals will be anesthetized by inhalation of isoflurane (2-4 %) through a nose cone for the duration of the study. A scavenging system traps the exhaled anesthetic gas. Additional anesthetic will be administered if the respiration rate becomes rapid, if the animal responds to a moderate toe pinch or if the animal starts to move.
Animals are visually monitored throughout the imaging procedure. Contrast material may be used during the imaging procedure. Two commonly used contrast agents are Fenestra VC and LC? which are iodinated agents for vascular and liver enhancement, respectively. For both of these agents, the standard dose 0.4 and 2.5 mL for mice and rats, respectively. The animal is positioned on the imaging table (head first, prone). A heating pad is placed beneath the animal in order to maintain an appropriate body temperature. Body temperature may be monitored throughout the study using a rectal probe. The imaging table is translated to move the animal into the scanner for imaging. Data are acquired with the system with x-ray tube voltage of 60-80 kVp, tube currents of 200-500 uA and exposures per view of 300 ms for 200 to 400 views.
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