Functional MRI studies for awake animals are attracting increased attention, for their potential to capture awake-specific neuronal responses. In the current awake MRI methods, fixing apparatuses implanted in the brain by surgery [1] and acclimation procedures by training [2] have been explored, to suppress head movement in the scanner. However, these methods require technical proficiency and, if the animal accommodation space in the MRI coils is small, a bulky apparatus cannot be used. To our knowledge, no awake MRI methods applicable to smaller animal accommodation spaces, such as the latest mouse brain cryogenic coils, have been reported. At the ISMRM annual meeting in 2013, we reported an awake MRI method using clothes designed to fit tightly over the mouse body [3]. This approach enables the head motion to be suppressed in a non-invasive manner. Another potential advantage of this approach is that the flexible mouse clothes are applicable to any shape of MRI coils, such as cryogenic coils with a narrower animal accommodation space [4], simply by customizing the clothes design. The aim of this study is to demonstrate that the awake MRI method with restrictive mouse clothes is actually applicable to MRI experiments using a mice brain cryogenic coil system.MRI experiments were performed with a 7.0 Tesla Bruker Biospec 70/20 scanner and a mouse brain 2-channel phased array surface cryogenic coil (Bruker BioSpin). The mouse clothes were designed to fit the sample accommodation space of the cryogenic coil system (Fig. 1). The experiments were performed on adult male C57BL/6 mice (22–25 g). For the first experience of wearing the clothes, the mice were anesthetized with 2% isoflurane, placed in the clothes, and fixed within the MRI cradle. At 60 minutes after cessation of the anesthesia, FISP images (FOV = 18 x 18 mm², matrix = 90 x 90, resolution = 0.2 x 0.2 mm², slice thickness = 1.5 mm, number of slices = 5, TR/TE = 2.3/1.15 ms, flip angle = 60°, NEX = 1, and scan repetition time = 1 s) were acquired for 18 minutes. The standard deviations (SDs) of the movements of the mouse brains in the three directions of Left–Right (L–R), Superior–Inferior (S–I), and Anterior–Posterior (A–P) were calculated using SPM8, based on the acquired FISP images. Throughout the experiments, the mice were maintained at 37±1°C by a heating pad, and the respiration and heart rates were monitored.First, FISP images of an awake mouse wearing the clothes previously designed for room temperature coils were acquired using the cryogenic coil, and we found that the mice tended to escape backward in the clothes. Therefore, we newly designed clothes to prevent the backward escape. However, we encountered another problem. The mouse head slipped down within the clothes, due to the shape of the animal accommodation space in the cryogenic coil system, resulting in a longer distance between the mouse head and the cryogenic coil and worse physiological conditions. Thus, we improved the clothes to prevent the mouse head from sliding down (Fig. 1). By using the newly designed clothes, the respiration and heart rates of the mice stably remained within the ranges normally observed in awake mice during the awake MRI experiments. The SDs of the head movements of the awake mice were similar to those of the anesthetized mice restrained with ear and bite bars, in all three directions (Fig. 2). The image of the awake mouse has a slightly lower SNR and a similar level of blurring suppression, as compared to the image of the anesthetized mouse (Fig. 3).The spatial resolution required for general functional MRI is about 0.2 mm in the Left–Right and Superior–Inferior directions and about 0.4 mm in the Anterior–Posterior direction. Therefore, the target SD values should be within 0.1 mm in the Left–Right and Superior–Inferior directions and 0.2 mm in the Anterior–Posterior direction. In this study, we successfully achieved these criteria, by using newly designed clothes applicable to the cryogenic system. The head motion of the awake mice was considered to be suppressed to an extent comparable to that of the anesthetized mice, since the SDs of the movements of the awake mice were similar to those of the anesthetized mice in all three directions.We demonstrated that the awake MRI method, using soft immobilization by designed clothes, is applicable to a cryogenic coil system. Our method will greatly contribute to brain function studies by combined use with fMRI methods.