[Cardio-pulmonary vascular system. Three-dimensional quantitative evaluation by microcomputed tomography]

Microvascularization of the human central and peripheral nervous system: A new microcomputed tomography method

Microcomputed X-ray tomography (microCT), developed since the late 1990s, is a miniaturized version of the tomographs used daily in medical imaging. It produces vascular images that are different from those obtained by microradiography, in particular by facilitating the vision in space, thus understanding microvascularisation. The anatomical specimens, once treated with formalin, are injected with a mixture made of gelatin containing a contrast product (barium) and then analyzed by microCT. The acquisition times that can exceed 24hours and metal sheets used for X-ray filtering vary according to the sample. The projection images are reconstructed to produce 2D sections. These are combined for the reconstruction of 3D models using a volume rendering software. Four examples will allow the imaging of microvascularization: the inferior alveolar nerve, the cerebral cortex and pia-mother, brain stem, central gray nuclei (ganglia at the base of the brain). Small capillaries are highlighted using high-end software for reconstruction. Conventional software or freeware cause a considerable loss of information on small vessels that are not visualized. The VGStudio max high-end software allows the production of videos that are particularly useful for 3D exploration and teaching (four videos are provided with this article).

Micro computed tomography for vascular exploration

Vascular exploration of small animals requires imaging hardware with a very high spatial resolution, capable of differentiating large as well as small vessels, in both in vivo and ex vivo studies. Micro Computed Tomography (micro-CT) has emerged in recent years as the preferred modality for this purpose, providing high resolution 3D volumetric data suitable for analysis, quantification, validation, and visualization of results. The usefulness of micro-CT, however, can be adversely affected by a range of factors including physical animal preparation, numerical quantification, visualization of results, and quantification software with limited possibilities. Exacerbating these inherent difficulties is the lack of a unified standard for micro-CT imaging. Most micro-CT today is aimed at particular applications and the software tools needed for quantification, developed mainly by imaging hardware manufacturers, lack the level of detail needed to address more specific aims. This review highlights the capabilities of micro-CT for vascular exploration, describes the current state of imaging protocols, and offers guidelines and suggestions aimed at making micro-CT more accurate, replicable, and robust.