DICOM PS3.17 2020a - Explanatory Information

WWW.2 Encoding Example (Current)
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## WWW.2 Encoding Example

This section illustrates the usage of the Section C.8.33.2 “Tractography Results Module” in PS3.3 in the context of the Tractography Results IOD.

Figure WWW-1. Two Example Track Sets. "Track Set Left" with two tracks, "Track Set Right" with one track.

Figure WWW-1 shows two example track sets. The example consists of:

- Two track sets "Track Set Left" and "Track Set Right"

  - Track Set Sequence (0066,0101) => each item describes one track set.

- Track Set "Track Set Left" contains two tracks "A" and "B"

  - Track Sequence (0066,0102) => each item describes one track.

- Track "A" consists of:

  - 4 points

    - Point Coordinates Data (0066,0016) => describes the coordinates for all points in the track.

  - Different color for each point

    - Recommended Display CIELab Value List (0066,0103) => describes the colors for all points in the track.

  - Fractional Anisotropy for each point

    - On how the values are stored, see description in "Encoding of Measurement Values" below.

  - Apparent Diffusion Coefficient for point 1 and 3

    - On how the values are stored, see description in "Encoding of Measurement Values" below.

- Track "B" consists of:

  - 3 points

    - Point Coordinates Data (0066,0016) => describes the coordinates for all points in the track.

  - Same color for each point

    - Recommended Display CIELab Value (0062,000D) => describes the color for all points in the track.

  - Fractional Anisotropy for each point

    - On how the values are stored, see description in "Encoding of Measurement Values" below.

  - Apparent Diffusion Coefficient for point 2

    - On how the values are stored, see description in "Encoding of Measurement Values" below.

- Encoding of Measurement Values for Tracks "A" and "B"

  - For storing measurement values like Fractional Anisotropy or Apparent Diffusion Coefficient values on specific points on a track the overall view over all tracks of a given track set is needed. Only tracks shall be grouped in track sets that share a specific type of measurement value.

  - Measurements Sequence (0066,0121) => each item describes one value type of all tracks in the track set (here: "Track Set Left" contains two value types: Fractional Anisotropy and Apparent Diffusion Coefficient).

  - Measurement Values Sequence (0066,0132) => one item for each track of a track set.

    - When used to store Fractional Anisotropy values:Since a Fractional Anisotropy value is stored for each point in both tracks of "Track Set Left", Floating Point Values (0066,0125) contains an array of Fractional Anisotropy values for tracks "A" and "B" respectively. Track Point Index List (0066,0129) is absent since there is a Fractional Anisotropy value associated with every point in Point Coordinates Data (0066,0016).

    - When used to store Apparent Diffusion Coefficient values:Since an Apparent Diffusion Coefficient value is stored only for a subset of points in both tracks of "Track Set Left", Track Point Index List (0066,0129) contains indices to the track points in Point Coordinates Data (0066,0016) and Floating Point Values (0066,0125) contains a measurement value for every track point referenced in Track Point Index List (0066,0129).

- Track Set "Track Set Right" contains one track "C"

- Track "C" consists of:

  - 3 points

    - Point Coordinates Data (0066,0016) => describes the coordinates for all points in the track.

  - Same color for all points

    - Recommended Display CIELab Value (0062,000D) => describes the color for all points in the track set (Note: In this example this Attribute is stored on Track Set level).

  - No measurement values

The table WWW-1 shows the encoding of the Tractography Results module for the example above. In addition to the two example track sets the table WWW-1 also encodes the following information:

- Within "Track Set Left" the mean Fractional Anisotropy values for track "A" (0.475) and "B" (0.667).

- For "Track Set Left" the maximum Fractional Anisotropy value (0.9).

- Diffusion acquisition, model and tracking algorithm information.

- Image instance references used to define the Tractography Results instance.

Table WWW-1. Example of the Tractography Results Module

Name | Tag | Value | Comment
--- | --- | --- | ---
Instance Number | (0020,0013) | 1 |
Content Label | (0070,0080) | Left and Right |
Content Description | (0070,0081) | Two Sample Tracksets |
Content Creator's Name | (0070,0084) | <empty> | Type 2 Attribute
Content Date | (0008,0023) | 20150529 |
Content Time | (0008,0033) | 121933.000000 |
Track Set Sequence | (0066,0101) |  |
| Item 1 (First Track Set "Track Set Left")
>Track Set Number | (0066,0105) | 1 |
>Track Set Label | (0066,0106) | Track Set Left |
>Track Set Anatomical Type Code Sequence | (0066,0108) |  |
>>Code Sequence Macro Values | (0008,0100) (0008,0102) (0008,0104) | (389080008, SCT, "White matter of brain and spinal cord") | CID 7710
>>Modifier Code Sequence | (0040,A195) |  |
| Item 1
>>>Code Sequence Macro Values | … | (7771000, SCT, "Left") | CID 244
>Track Sequence | (0066,0102) |  |
| Item 1 (First Track "A")
>>Point Coordinates Data | (0066,0016) | 0, 0, 0 1.5, 0.2, 0 3.5, -0.1, 0 5.5, 0.5, 0 | Coordinates of A1, A2, A3, A4
>>Recommended Display CIELab Value List | (0066,0103) | 47270/40385/52501/ 34751/53214/49924/ 57318/11632/54042 22077/53113/5901/ | Colors of A1, A2, A3, A4
Item 2 (Second Track "B")
>>Point Coordinates Data | (0066,0016) | 0, -4, 0 2,-3.8, 0 4,-4, 0 | Coordinates of B1, B2, B3
>>Recommended Display CIELab Value | (0062,000D) | 57318/11632/54042 | Color of B1, B2, B3
>Measurements Sequence | (0066,0121) |  |
| Item 1 (Fractional Anisotropy (FA) values stored on each Track)
>>Concept Name Code Sequence | (0040,A043) |  |
>>>Code Sequence Macro Values | … | (110808, DCM, "Fractional Anisotropy") | CID 7263
>>Measurement Units Code Sequence | (0040,08EA) |  |
>>>Code Sequence Macro Values | … | (1, UCUM, "no units") | CID 82
>>Measurement Values Sequence | (0066,0132) |  |
| Item 1 (FA Values for each point on first Track "A")
>>>Floating Point Values | (0066,0125) | 0.2,0.4,0.5,0.8 | FA values of A1, A2, A3, A4
Item 2 (FA Values for each point on second Track "B")
>>>Floating Point Values | (0066,0125) | 0.3, 0.8, 0.9 | FA values of B1, B2, B3
Item 2 (Apparent Diffusion Coefficient (ADC) values stored on each Track)
>>Concept Name Code Sequence | (0040,A043) |  |
>>>Code Sequence Macro Values | … | (113041, DCM, "Apparent Diffusion Coefficient") | CID 7263
>>Measurement Units Code Sequence | (0040,08EA) |  |
>>>Code Sequence Macro Values | … | (1, UCUM, "no units") | CID 82
>>Measurement Values Sequence | (0066,0132) |  |
| Item 1 (ADC Values stored on 1st and 3rd point of first Track "A")
| >>>Floating Point Values | (0066,0125) | 0.6,0.7 | ADC values of A1 and A3
>>>Track Point Index List | (0066,0129) | 1, 3 |
Item 2 (ADC Values stored on 2nd point of second Track "B")
>>>Floating Point Values | (0066,0125) | 0.5 | ADC value of B2
>>>Track Point Index List | (0066,0129) | 2 |
>Track Statistics Sequence | (0066,0130) |  | Statistical values derived from each Track
| Item 1 (Mean FA values for Tracks "A" and "B")
>>Concept Name Code Sequence | (0040,A043) |  |
>>>Code Sequence Macro Values | … | (110808, DCM, "Fractional Anisotropy") | CID 7263
>>Modifier Code Sequence | (0040,A195) |  |
>>>Code Sequence Macro Values | … | (373098007, SCT, "Mean") | CID 3488 (part of CID 7464)
>>Measurement Units Code Sequence | (0040,08EA) |  |
>>>Code Sequence Macro Values | … | (1, UCUM, "no units") | CID 82
>>Floating Point Values | (0066,0125) | 0.475, 0.667 |
>Track Set Statistics Sequence | (0066,0124) |  | Statistical values derived from whole track set
| Item 1 (Maximum FA value of whole Track Set "Track Set Left")
>>Concept Name Code Sequence | (0040,A043) |  |
>>>Code Sequence Macro Values | … | (110808, DCM, "Fractional Anisotropy") | CID 7263
>>Modifier Code Sequence | (0040,A195) |  |
>>>Code Sequence Macro Values | … | (56851009, SCT, "Maximum") | CID 3488 (part of CID 7464)
>>Measurement Units Code Sequence | (0040,08EA) |  |
>>>Code Sequence Macro Values | … | (1, UCUM, "no units") | CID 82
>>Floating Point Value | (0040,A161) | 0.9 |
>Diffusion Acquisition Code Sequence | (0066,0133) |  |
>>Code Sequence Macro Values | … | (113223, DCM, "DTI") | CID 7260
>Diffusion Model Code Sequence | (0066,0134) |  |
>>Code Sequence Macro Values | … | (113231, DCM, "Single Tensor") | CID 7261
>Tracking Algorithm Identification Sequence | (0066,0104) |  |
| Item 1
>>Algorithm Family Code Sequence | (0066,002F) |  |
>>>Code Sequence Macro Values | … | (113211, DCM, "Deterministic") | CID 7262
>>Algorithm Name | (0066,0036) | Example |
>>Algorithm Version | (0066,0031) | 1.0 |
Item 2 (Second Track Set "Track Set Right")
>Track Set Number | (0066,0105) | 2 |
>Track Set Label | (0066,0106) | Track Set Right |
>Track Set Anatomical Type Code Sequence | (0066,0108) |  |
>>Code Sequence Macro Values | (0008,0102) (0008,0100) (0008,0104) | (389080008, SCT, "White matter of brain and spinal cord") | CID 7710
>>Modifier Code Sequence | (0040,A195) |  |
| Item 1
>>>Code Sequence Macro Values | … | (24028007, SCT, "Right") | CID 244
>Track Sequence | (0066,0102) |  |
| Item 1 (Single Track "C")
>>Point Coordinates Data | (0066,0016) | 6, 0.1, 0 5.8, -2, 0 6.2, -4.5, 0 | Coordinates of C1, C2, C3
>Recommended Display CIELab Value | (0062,000D) | 34751/53214/49924/ | Color of C1, C2, C3
>Diffusion Acquisition Code Sequence | (0066,0133) |  |
>>Code Sequence Macro Values | … | (113223, DCM, "DTI") | CID 7260
>Diffusion Model Code Sequence | (0066,0134) |  |
>>Code Sequence Macro Values | … | (113231, DCM, "Single Tensor") | CID 7261
>Tracking Algorithm Identification Sequence | (0066,0104) |  |
| Item 1
>>Algorithm Family Code Sequence | (0066,002F) |  |
>>>Code Sequence Macro Values | … | (113211, DCM, "Deterministic") | CID 7262
>>Algorithm Name | (0066,0036) | Example |
>>Algorithm Version | (0066,0031) | 1.0 |
Referenced Instance Sequence | (0008,114A) |  |
| Item 1
>Referenced SOP Class UID | … | 1.2.840.10008.5.1.4.1.1.4 | MR Image Storage
>Referenced SOP Instance UID | … | 1.2.3.4.1 |
Item 2
>Referenced SOP Class UID | … | 1.2.840.10008.5.1.4.1.1.4 | MR Image Storage
>Referenced SOP Instance UID | … | 1.2.3.4.2 |
… |  |  |
Item n
>Referenced SOP Class UID | … | 1.2.840.10008.5.1.4.1.1.4 | MR Image Storage
>Referenced SOP Instance UID | … | 1.5.6.1 |

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DICOM PS3.17 2020a - Explanatory Information