In-Vivo MRI in Rodents: A Protocol for Optimal Animal Positioning

Magnetic resonance imaging (MRI) is a potentially powerful novel peripheral nerve diagnosis technique. To determine its validity, in-vivo preclinical studies are necessary. However, when using a rodent model, positioning rats and achieving high-resolution images can be challenging. We present a short report that outlines an optimal protocol for positioning rats for in-vivo MRI acquisition. Female Sprague-Dawley rats with sciatic nerve injury were induced into anesthesia using 4% isoflurane in oxygen and maintained at 1.5%. Rats were placed into a plexiglass cradle in a right lateral recumbent position, and a surface coil was placed over the left leg. Respiration rate and body temperature were monitored throughout the scan. Our protocol was successful as rats were able to undergo MRI scanning safely and efficiently. There were no adverse reactions, and clear images of the left sciatic nerve were obtained. Animal positioning took 30 minutes, and 5 different acquisitions were obtained in 2 hours. The total time from anesthesia induction to recovery was under 3 hours. Given the increasing interest in MRI diagnostic techniques, we hope this report aids other researchers studying peripheral nerve injury imaging in rat models.