Magnetic resonance imaging cerebral blood perfusion measurement in awake mice

Background: Cerebral blood perfusion (CBP) plays a vital role in delivering oxygen and essential nutrients to support neuronal activity. Researchers commonly use mouse models with magnetic resonance imaging (MRI) to study CBP and brain function. However, a major challenge in these studies is the use of anesthesia, which significantly alters cerebrovascular dynamics and metabolic activity. New method: A 3D-printed, custom-designed frame and head mounting plate were used with an existing Bruker mouse cradle. To evaluate the repeatability of CBP measurements in awake versus anesthetized conditions, we used a flow-sensitive alternating inversion recovery (FAIR) sequence on a wild-type mouse that underwent a three-day training before scanning to acclimate it to the MRI environment. Results: CBP was significantly higher under anesthesia than in the awake condition for both the whole brain and cortex (P < 0.001). Under anesthesia, the mean perfusion for was 70.9 ± 5.6 ml/min/100 g for the whole brain and 67.8 ± 8.5 ml/min/100 g for just the cortex. Under awake conditions, the whole brain perfusion was 51.1 ± 3.3 ml/min/100 g and 46.7 ± 3.4 ml/min/100 g for the cortex. Perfusion variability, measured by variance and standard deviation, was consistently higher under anesthesia. Comparison with existing methods: We built a unique mouse head stabilizing system for MRI and are the first to have specifically focused on CBP during awake conditions. Conclusions: Our findings confirm that anesthesia significantly increases CBP, affecting the accuracy, reproducibility and relevance of perfusion-related studies. Accordingly, we developed a practical, MRI-compatible setup for imaging awake mice and used it to measure perfusion for more reliable neuroimaging research.