3D imaging of the murine neurovasculature with μMRI and validation with μCT and optical microscopy.

Abstract

<p>(a) Photograph of a freshly excised mouse brain showing blue Microfil® perfused vessels (arrows). (b) X-ray radiograph of the same brain in which radio-opaque microfilled vessels are clearly visible. Arrows indicate major vessels that are also visible in (a). (c) Slice through the 3D R₂* map of the same brain. The Microfil-brain tissue interface is characterized by elevated R2* (hot colors) values. Note that background voxels are assigned R2* of zero. (d) ∼1.2 mm slab from another intact brain, in which μMRI-derived vasculature (gold) is overlaid on that acquired using μCT (purple). One can clearly visualize the vascular architecture and the agreement between μMRI and μCT. (e) Bright-field images (2×) of ROIs corresponding to colored squares in (d). Images are from a 1 mm thick, unstained brain section. Dark microfilled vessels provide corroboration of the μMRI data in (d). Arrows indicate major vessels that are also visible in (d). μCT data were resampled to match the μMRI spatial resolution, and the fractional vascular volume (FV) computed within 8×8×1 subvolumes for each dataset. The correlation between the μMRI and μCT-derived FVs for the 1 mm thick slice is plotted in (f). A similar analysis was conducted for the <i>whole</i> brain, wherein the FV was computed within 8×8×8 subvolumes for each dataset. The correlation between the μMRI and μCT-derived FVs for the <i>whole</i> brain is plotted in (g) and demonstrate good agreement between μMRI and μCT-derived vasculature. The red lines in (f) and (g) are the best linear fit to the data, and blue lines indicate the 95% confidence limits about the mean.</p