Background: The wall-to-lumen ratio (WLR) is an important parameter in vascular medicine because
it indicates the character of vascular wall as well as the degree of stenosis. Despite
the advances in medical imaging technologies, it is still difficult to measure the
thin-walled normal intracranial arteries, and the reports on the WLR of normal intracranial
artery are limited. It might be possible to calculate the WLR using the indocyanine
green (ICG) angiography, which is used to observe intracranial vessels during microsurgery.
Purpose: To evaluate the WLR of normal intracranial arteries using ICG angiography.
Materials and Methods: From the three cases in which ICG angiography was recorded with a ruler during microsurgery,
20 measurement points were chosen for the analysis. The ICG was injected intravenously
with a dose of 0.2 mg/kg, and the vessels were inspected at high magnification using
an operating microscope equipped with near-infrared illumination system. The vessel
outer diameter and the luminal diameter were measured using the images before and
after the ICG arrival based on the pixel ratio method using a ruler as reference,
respectively. The WLR was calculated as 0.5 × (vessel outer diameter − vessel luminal
diameter). Results: The WLR (mean ± standard deviation) of normal intracranial arteries was 0.086 ± 0.022.
The WLR tended to be high in small arteries. Conclusion: The WLR of normal intracranial arteries calculated using ICG angiography was consistent
with the WLR reported in the previous reports based on human autopsy.
Key-words:
In vivo - indocyanine green angiography - intracranial artery - normal - vascular
wall - wall-to-lumen ratio
