3D micro-CT imaging of the postmortem brain

Magnetic resonance microscopy (μMRI) is becoming an important tool for non-destructive analysis of fixed brain tissue. However, unlike MRI, X-ray computed tomography (CT) scans show little native soft tissue contrast. In this paper, we explored the use of contrast enhanced (brains immersion stained in iodinated CT contrast media) micro-CT (μCT) for high resolution 3D imaging of fixed normal and pathological brains, compared to μMRI and standard histopathology. An optimum iodine concentration of 0.27 M resulted in excellent contrast between gray and white matter in normal brain and a wide range of anatomical structures were identified. In glioma bearing mouse brains, there was clear deliniation of tumor margin which closely matched that seen on histopathology sections. μCT tumor volume was strongly correlated with histopathology volume. Our data suggests that μCT image contrast in the immersion-stained brains is related to axonal density and myelin content. Compared to traditional histopathology, our μCT approach is relatively rapid and less labor intensive. In addition, compared to μMRI, μCT is robust and requires much lower equipment and maintenance costs. For simple measurements, such as tumor volume and non-destructive postmortem brain screening, μCT may prove to be a valuable alternative to standard histopathology or μMRI.