Abstract: The present invention relates to a conversion kit for converting a machine designed for intravascular injection of solutions, such as parenteral solutions, using high-pressure syringes, to a machine that can be used for injection using smaller manual syringes. The conversion kit, includes at least one conversion vessel (13) for releasable but substantially non-rotary reception of a high-pressure syringe with a cylindrical guide (19) formed through a receiving head (14) of the conversion vessel (13) and a recess (17) formed in the upper surface of the receiving head (14). The recess (17) may also receive the radial end regions of wing extensions of a manual syringe of predetermined size. The conversion kit also includes at least one reducing sleeve (23) for reducing the effective inner diameter of the guide (19), the reducing sleeve (23) adapted to snugly receive the outer diameter of a manual syringe (12).