Figure 1. Transcranial macroscopic imaging.

(A) Schematic of the macroscopic imaging set up. (B) Dorsal view of the position of the head plate on the skull. The interparietal bone and the nasal, frontal, and parietal bones are all visible. (C) An exposed mouse skull during imaging before CSF tracer has appeared, clearly showing all cranial sutures of the intact skull. Scale bar: 1 mm (D) Schematic of a lateral view of CSF tracer entering the cisterna magna (CM) and traveling from the basal cistern along the glymphatic pathway. (E, left panel) Macroscopic imaging of glymphatic influx in a ketamine-xylazine anesthetized wildtype mouse at 20 minutes post CM injection (BSA-647; 10 μL at 2 μL/min). CSF tracer is seen in the olfactofrontal cistern around the rostral rhinal vein below the nasofrontal suture, along some parts of the superior sagittal sinus below the sagittal suture, and in the pineal recess surrounding the transverse sinus below the lambdoid suture. (E, right panel) Digital magnification of the image on the left shows the high spatial resolution obtained with these microscopes. CSF tracer travels within the perivascular spaces of the middle cerebral artery (MCA)¹⁰. Scale bar: 0.5 mm (F) Experimental timeline. An anesthetized wildtype mouse received a moderate traumatic brain injury (TBI)²⁴ and immediately after a CM injection (BSA-647; 10 μL at 2 μL/min), followed by 60 min of macroscopic imaging. (G) Time-lapse images of CSF tracer transport after TBI (dashed line). Scale bar: 1 mm (H) Influx area (mm²) over each hemisphere during the 60-min experiment, quantified from the ROIs in (G), the hemisphere that received TBI (ipsilateral) and the hemisphere that did not (contralateral).