DICOM PS3.17 2017b - Explanatory Information

EEEE.3 Relationship of Derived Diffusion Model Parametric Maps to Diffusion Weighted Source Images
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## EEEE.3 Relationship of Derived Diffusion Model Parametric Maps to Diffusion Weighted Source Images

This example illustrates how to describe the manner in which an ADC Parametric Map image was derived from B0 and B1000 images. The intent is to provide links to the images, not to replicate all the information that can be provided in the Quantity Definition Sequence.

This particular example illustrates the reference from an ADC Parametric Map to a pair of Enhanced MR images, one for each b-value (or a pair of subsets of frames of a single Enhanced MR image), but the same principle is applicable when single frame IODs are used as source or derived image.

- Derivation Image Sequence (0008,9124)

  - Derivation Description (0008,2111) = "Calculation of mono-exponential ADC from log of ratio of B0 and B1000 images"

  - Derivation Code Sequence (0008,9215)

    - (113041, DCM, "Apparent Diffusion Coefficient")

    - (113250, DCM, "Mono-exponential ADC from log of ratio of two samples")

  - Source Image Sequence (0008,2112)

    - Item 1:

      - Referenced SOP Class UID (0008,1150) of B0 image

      - Referenced SOP Instance UID (0008,1155) of B0 image

      - Referenced Frame Number (0008,1160) of B0 frames in image

      - Purpose of Reference Code Sequence

        - (121322, DCM, "Source image for image processing operation")

    - Item 2:

      - Referenced SOP Class UID (0008,1150) of B1000 image

      - Referenced SOP Instance UID (0008,1155) of B1000 image

      - Referenced Frame Number (0008,1160) of B1000 frames in image

      - Purpose of Reference Code Sequence

        - (121322, DCM, "Source image for image processing operation")

In this approach:

- since multiple items are permitted in the Derivation Code Sequence (0008,9215), both the general concept (calculation of ADC) and the specific method have been listed; alternatively, just one or the other could be provided

- a textual description has also be provided, which in this case provides more information than the structured content (i.e., about the b-values used)

- a generic purpose of reference code has been used, since only a single code is permitted and there is no mechanism (other then creating pre-coordinated codes for every possible b-value) to convey which image (set) was acquired with which b-value; the more specific alternative of a coded concept for "source image for ADC calculation" would add no value over the concept already described in Derivation Code Sequence

- the SOP Instance UID in the first and second items may be the same, but a different range of frames referenced, e.g., if all of the source frames (all of the b-values) are in the same instance, as is required by the IHE Diffusion (DIFF) profile (http://wiki.ihe.net/index.php/MR_Diffusion_Imaging); if all of the frames in a single source image are used, then only a single item is necessary and the Referenced Frame Number can be omitted.

- all of the images have been listed in a single item of Derivation Image Sequence (0008,9124); alternatively, multiple items of Derivation Image Sequence (0008,9124) could be sent. one for each of the different b-values used; this would allow Derivation Description (0008,2111) to communicate which set contained which b-value, but there is no structured way to communicate such numeric parameters (other then creating pre-coordinated codes for every possible b-value)

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DICOM PS3.17 2017b - Explanatory Information