In medical imaging, resolution is the ability to distinguish two adjacent objects and a measurement of image quality. The resolution of tomographic images is a function of slice thickness, field of view (FOV) and matrix size. The resolution in plane is a function of FOV / matrix size.

The resolution time or temporal resolution is the shortest time duration between two events that can be measured.

Image resolution is a measurement of the scanned, printed, or displayed image quality. Picture resolution on a printed photo or page is measured in dots per inch (DPI). For digital files, image resolution is expressed in pixels per inch (PPI).
The quality of pixel-based images is directly determined by resolution choices. Higher image resolution results in more detailed images but requires more storage space in a picture archiving and communication system.
The resolution for x-ray images can be defined as the period length of the finest grid that can be viewed without difficulty.

The resolution element has the size of the smallest spatially resolved region in an image. It may be anisotropic, e.g. with an asymmetric acquisition matrix or slice thickness, and may be larger than the pixel or voxel.

(LCR) The low contrast resolution describes the ability to discriminate between tissues with slightly differences in attenuation properties. The LCR depends on the stochastic noise.
The low contrast resolution is usually expressed as the minimum detectable size of an image structure, for a fixed percentage difference in contrast relative to the adjacent background.
A strength of computed tomography (CT) is its ability to visualize structures of low contrast in an object, a task that is limited by noise and is closely associated with the radiation dose. For example, a reduction of the dose at constant spatial resolution affects the visibility of structures with low contrast (e.g. vessels in the liver), due to increased noise. The visibility of these low contrast structures can partly be improved by decreasing the spatial resolution, while keeping the dose constant.

See also CT Number, Image Quality and Low Contrast Detectability.