Through Skull Fluorescence Imaging of the Brain in a New Near-Infrared Window

TL;DR

This paper demonstrates a non-invasive fluorescence imaging technique through the skull of mice using single-walled carbon nanotubes in a new near-infrared window, enabling high-resolution, real-time visualization of cerebral vasculature and blood flow.

Contribution

It introduces a novel through-skull fluorescence imaging method in a new near-infrared window, avoiding invasive procedures and achieving deeper, faster imaging of brain vasculature.

Findings

Imaging depth exceeds 2 mm with sub-10 micrometre resolution.

Achieves real-time blood flow monitoring at ~5.3 frames per second.

Enables dynamic assessment of stroke models without craniotomy.

Abstract

To date, brain imaging has largely relied on X-ray computed tomography and magnetic resonance angiography with limited spatial resolution and long scanning times. Fluorescence-based brain imaging in the visible and traditional near-infrared regions (400-900 nm) is an alternative but currently requires craniotomy, cranial windows and skull thinning techniques, and the penetration depth is limited to 1-2 mm due to light scattering. Here, we report through-scalp and through-skull fluorescence imaging of mouse cerebral vasculature without craniotomy utilizing the intrinsic photoluminescence of single-walled carbon nanotubes in the 1.3-1.4 micrometre near-infrared window. Reduced photon scattering in this spectral region allows fluorescence imaging reaching a depth of >2 mm in mouse brain with sub-10 micrometre resolution. An imaging rate of ~5.3 frames/s allows for dynamic recording of blood perfusion in the cerebral vessels with sufficient temporal resolution, providing real-time assessment of blood flow anomaly in a mouse middle cerebral artery occlusion stroke model.