gms | German Medical Science

Objective: Quantification of vasospasms is a major difficulty in studies using experimental subarachnoid hemorrhage (SAH) models. Here we demonstrate the feasibility of micro computed tomography (microCT) with subsequent reconstruction of the virtual 3-dimensional vascular tree to detect and precisely quantify cerebral vasospasms by volumetric analysis of vascular segments.

Method: Mice were randomized to SAH or sham treatment in a prospective manner. Endovascular perforation of the circle of Willis was used to produce SAH. At day 3 the vascular system was filled with a pre-stained radiopaque cast and brains were subjected to high-resolution microCT with subsequent 3-dimensional reconstruction of the vascular tree using Amira software. Auto-segmentation of middle cerebral, anterior cerebral, internal carotid, and basilar arteries was performed, vessel diameters were visualized with a pseudo-color code, followed by volumetric analysis of the vascular segments. In addition, vessel diameters were quantified by conventional 2-dimensional imaging.

Results: 56 vascular segments of 8 brains were analyzed. 3-dimensional reconstruction using the microCT data sets showed a highly accurate image of the circle of Willis and individual anatomical variations in all cases, and vascular diameters were adequately reflected by the pseudo-color code. Total vessel volume was significantly smaller in SAH animals compared to sham (SAH: 54±11nl; sham: 89±5nl; p<0.05). Analysis of single segments revealed significant differences of middle cerebral artery (SAH: 10±5nl; sham: 17±3nl; p<0.05) and basilar artery (SAH: 27±5nl; sham: 38±3nl; p<0.05). In contrast, 2-dimensional imaging of vessel diameters showed a higher variability and smaller differences for middle cerebral (SAH: 92±25µm; sham: 133±19µm; p<0.05) and basilar artery (SAH: 172±23µm; sham: 198±4µm).

Conclusions: MicroCT with analysis of the virtual 3-dimensional vascular tree offers the advantage of volumetric analysis and color-coded illustration of vessel diameters over whole vascular segments. Low variations in the volumetric parameters compared to 2-dimensional optical evaluation of the circle of Willis and intuitive estimation of vasospasms by visualization of the color-coded vascular tree make microCT a promising new tool for quantification of post-hemorrhagic vasospasms.