A collection of slices with the same orientation. Multi-stack acquisitions are possible when the stack parameter is greater than one, for example in lumbar spine CT exams with individual angulation (oblique) for every disc.

A vector is a quantity characterized by a magnitude (in mathematics a number, in physics a number times a unit) and a direction (and a point of application), often represented graphically by an arrow. The length of the line segment represents the magnitude, and its orientation in space represents its direction. Vector quantities can be added to or subtracted from one another. Used in diagnostic imaging to describe forces, e.g. magnetic moment, spin, magnetization etc.