Imagine being able to observe the health status of your brain streaming real-time in 3D. Medical treatments for a range of neurovascular, neurological, cancerous and trauma-induced conditions would be far more effective, because snapshots over time would reveal the progression of a disease or damage.
This is not science fiction. Scientists at Stanford University have reported a new brain imaging technique in the journal Nature Medicine that takes a major step towards this goal. Proof of concept was demonstrated using mice.
a) Two-dimensional projection of a three-dimensional stack of 220 images of dye-labeled vasculature acquired at ~3-μm increments over ~660 μm in depth. Supplementary Video 1 shows the entire image stack. (b) Time-lapse image sequence acquir…
According to the paper: (excerpts from their Abstract)
Here we introduce cellular-level time-lapse imaging deep within the live mammalian brain by one- and two-photon fluorescence microendoscopy over multiple weeks. Bilateral imaging sites allowed longitudinal comparisons within individual subjects, including of normal and diseased tissues.
To illustrate disease studies, we tracked deep lying gliomas by observing tumor growth, visualizing three-dimensional vasculature structure and determining microcirculatory speeds.
Supplementary Video 1 | 3D image stack of hippocampal blood vessels acquired in a live
mouse by two-photon microendoscopy and intravascular injection of fluorescein-dextran.
On day 22 following implantation of an imaging guide tube, a 1-mm-diameter microendoscope
was used to create an image stack extending 660 μm in depth and containing 220 images
acquired at 3 μm axial increments. The field of view is 1 mm in lateral extent. The 2D projection
of this image stack is shown in Fig. 3a.
From the Nature blog
The technology relies on miniature glass tubes, about half the width of a grain of rice, that are implanted into the deep brain of anaesthetized mice. A tiny optical instrument called a microendoscope is then threaded inside the tube, allowing researchers to return to exactly the same brain location — down to the level of an individual cell — repeatedly over weeks or months.
As a proof of principle, the Stanford team tracked the growth of glioma brain cancer cells. The following video shows a three-dimensional stack of 220 images each taken about 3 micrometers apart to reveal blood vessel growth in the hippocampus of wild-type mice.
Take a look at what happens over time:
A time-lapse image sequence acquired in the dorsal striatum of an individual mouse by two-photon microendoscopy and intravascular injection of fluoresceindextran, on the specified days relative to the implantation of the imaging guide tube. Each image is labeled by the day of
image acquisition relative to the first imaging session and is a 2D projection of 5 images acquired at 5 μm axial increments from a stack of 180 μm total axial extent. Scale bar is 100 μm.