DICOM PS3.3 2018d - Information Object Definitions

A.75 Parametric Map IOD

A.75.1 Parametric Map IOD Description

The Parametric Map Information Object Definition (IOD) specifies a multi-frame image representing pixels with real world values. Parametric Maps are either integer or floating point.

The Parametric Map IOD does not include the full set of acquisition parameters of any acquired images from which they were derived, e.g., cardiac phase. An application rendering or processing the Parametric Map may need to access the source images for such information.

The Parametric Map IOD requires the presence of VOI LUT (window) information with the intent that at a minimum the image be renderable without special processing. The output space is defined as P-Values to achieve consistency.


  • The VOI LUT mechanism specifically supports floating point values, and there is no expectation that it be limited to integer input or output ranges.

  • Even though the output of the VOI LUT is not constrained to be integer values, implicit scaling of the output range to the input range of an integer-based Palette Color LUT can be used to apply pseudo-color for display. Pseudo-color mapping information may be encoded with the image. This may be applied at the discretion of the receiving application or it may use a separate DICOM Color Palette IOD or some other mechanism.

The Parametric Map IOD encodes one or more parameters as an image. Other Image IODs may be used to encode related information, and instances of them may be referenced from the Parametric Map, as the source from which a parameter was derived, or some other relationship.


  • The Blending Presentation State IOD may be used to describe how (selected frames of) a Parametric Map instance may be superimposed on, say, frames of acquired images for anatomical reference encoded as instances of other Image IODs, as well as the relative opacity and pseudo-color applicable to the overlying frames.

  • Commonality of the same Frame of Reference UID also allows an application to relate Parametric Map instances and other Image instances, in the absence of explicit references.

  • The Parametric Map IOD is not restricted to encoding only a single parameter in one instance. Since it is a multi-frame object, and since the type of parameter is encoded in the Real World Value Mapping Functional Group Macro, which may vary on a per-frame basis, the parameter may also vary from frame-to-frame. In such cases, the Multi-frame Dimension Module may be used to highlight this, by specifying the Quantity Definition Sequence (0040,9220) as a Dimension Index.

DICOM PS3.3 2018d - Information Object Definitions