The imaging system can comprise a plurality of elongated rails, a scanhead assembly, and a small animal mount assembly. The scanhead assembly is selectively mounted onto a first rail and is constructed and arranged for movement in a linear bi-directional manner along the longitudinal axis of the first rail. The small-animal mount assembly is selectively mounted onto a second rail and is constructed and arranged for movement in a linear bi-directional manner along the longitudinal axis of the second rail. The second rail being mounted relative to the first rail such that the longitudinal axis of the second rail is at an angle to the longitudinal axis of the first rail. The small-animal mount assembly can include a table member suitable for mounting a small animal. The table member can be selectively positionable into a desired table plane. The imaging system can also comprise a needle injection assembly that is selectively mounted onto the third rail and is constructed and arranged for movement in a linear bi-directional manner along the longitudinal axis of the third rail. The third rail being mounted relative to the second rail and the first rail such that the longitudinal axis of the third rail is substantially coaxial to the longitudinal axis of the first rail.Selon linvention, un système dimagerie peut comprendre une pluralité de rails allongés, un ensemble de tête de scanner et un ensemble supportant un petit animal. La tête de scanner est montée de manière sélective sur un premier rail et est construite et disposée de façon à se déplacer dans un sens bidirectionnel linéaire, le long dun axe longitudinal du premier rail. Ledit ensemble supportant un petit animal est monté de manière sélective sur un deuxième rail et est construit et disposé de façon à se déplacer dans un sens bidirectionnel linéaire le long de laxe longitudinal du deuxième rail. Le deuxième rail est monté par rapport au premier rail, de sorte que laxe longitudinal du deuxième rail est incliné
