Engineering Senior Design Project: Mouse Positioning Cradle

Abstract

The goal of this project was to design a cradle for restraining and positioning mice in an MRI machine. The sponsor, University of Arizona faculty member Dr. Marty Pagel, collects MRI images of animals for cancer research. Previously, the best option available for restraining the anesthetized mouse subject in the MRI consisted of little more than taping the subject to a PVC pipe. The engineering team created a new cradle designed to be easy to use while also removing the necessity of applying tape directly to the mice subjects for restraint, and providing a more even heat dispersion over them while in the MRI. The new cradle system features a removable sled that secures the mouse, and it provides spaces for catheters and monitoring devices, a connector for the existing heater tube that directs the hot air around the subject from under the sled, and an adjustable vertical positioning screw for improved target-centering capability in the MRI machine. The new design improved the repeatability of MRI scans and reduced potential sources of injury to the animal subject while maintaining the ease of use similar to the previous cradle.