C.8.33.2 Tractography Results Module

C.8.33.2 Tractography Results Module (Current)
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Table C.8.33-2 specifies the Attributes of the Tractography Results Module, which describe the tracks and measurements in the tractography results.

Table C.8.33-2. Tractography Results Module Attributes

Attribute Name	Tag	Type	Attribute Description
Include Table 10-12 “Content Identification Macro Attributes”
Content Date	(0008,0023)	1	The date the content creation started.
Content Time	(0008,0033)	1	The time the content creation started.
Track Set Sequence	(0066,0101)	1	Describes the track sets that are contained within the data. One or more Items shall be included in this Sequence.
>Track Set Number	(0066,0105)	1	Identification number of the Track Set. Uniquely identifies a track set within this SOP Instance. Shall start at a value of 1, and increase monotonically by 1.
>Track Set Label	(0066,0106)	1	User-defined label identifying this Track Set. This may be the same as Code Meaning (0008,0104) of Track Set Anatomical Type Code Sequence (0066,0108).
>Track Set Description	(0066,0107)	3	User-defined description for this Track Set.
>Track Set Anatomical Type Code Sequence	(0066,0108)	1	Sequence defining the specific property type of this Track Set. Only a single Item shall be included in this Sequence.
>>Include Table 8.8-1 “Code Sequence Macro Attributes”			BCID 7710 “Tractography Anatomic Site”.
>> Modifier Code Sequence	(0040,A195)	3	A Sequence of Items modifying or specializing the Track Set Anatomical Type Code Sequence. One or more Items shall be included in this Sequence.
>>>Include Table 8.8-1 “Code Sequence Macro Attributes”			DCID 244 “Laterality”.
>Track Sequence	(0066,0102)	1	Describes individual tracks part of the track set. One or more Items shall be included in this Sequence.
>>Point Coordinates Data	(0066,0016)	1	Contains two or more point coordinates that define the track, encoded in x-y-z order, in mm in the Patient-Based Coordinate System associated with the Frame of Reference. The order of the encoded points is from the first point to the last point of the track. When referencing points in Point Coordinates Data (0066,0016) the index of the first point x,y,z triplet is 1 See Section C.27.2.1.1.
>>Recommended Display CIELab Value List	(0066,0103)	1C	Default triplet values in which it is recommended that the point shall be rendered. The units are specified in PCS-Values and the value is encoded as CIELab. See Section C.10.7.1.1. The number of triplets shall match the number of points stored in Point Coordinates Data (0066, 0016), and be encoded in the same order so as to correspond. Required if Recommended Display CIELab Value (0062, 000D) is not present in this Sequence Item nor in the containing Track Set Sequence (0066,0101) Item.
>>Recommended Display CIELab Value	(0062,000D)	1C	Default triplet value in which it is recommended that the track shall be rendered. The units are specified in PCS-Values and the value is encoded as CIELab. See Section C.10.7.1.1. Required if Recommended Display CIELab Value List (0066,0103) is not present in this Sequence Item and Recommended Display CIELab Value (0062, 000D) is not present in the containing Track Set Sequence (0066,0101) Item.
>Recommended Display CIELab Value	(0062,000D)	1C	Default triplet value in which it is recommended that the track set be rendered. The units are specified in PCS-Values, and the value is encoded as CIELab. See Section C.10.7.1.1. Required if neither Recommended Display CIELab Value (0062, 000D) nor Recommended Display CIELab Value List (0066,0103) are present in every Item of the Track Sequence (0066,0102).
>Recommended Line Thickness	(0066,0038)	3	Specifies the thickness of each track in the track set with which it is recommended to be rendered. The units shall be the same as the units of the coordinate system in which the point coordinates are specified.
>Measurements Sequence	(0066,0121)	3	Measurements for some or all points along the tracks. Each Item describes one type of measurement. See Section C.8.33.2.1 for more details. One or more Items shall be included in this Sequence.
>>Concept Name Code Sequence	(0040,A043)	1	Defines the type of measurement stored in this Item. Only a single Item shall be included in this Sequence.
>>>Include Table 8.8-1 “Code Sequence Macro Attributes”			DCID 7263 “Diffusion Tractography Measurement Type”
>>Measurement Units Code Sequence	(0040,08EA)	1	Units of measurement for the value in this Item. Only a single Item shall be included in this Sequence.
>>>Include Table 8.8-1 “Code Sequence Macro Attributes”			DCID 82 “Measurement Unit”.
>>Measurement Values Sequence	(0066,0132)	1	The measurement values for each track. The number and order of Items shall equal the Items in Track Sequence (0066,0102).
>>>Floating Point Values	(0066,0125)	1	Measurement values for points stored in Point Coordinates Data (0066, 0016) of the corresponding track in Track Sequence (0066,0102). If Track Point Index List (0066,0129) is absent, measurement values are stored for every point in Point Coordinates Data (0066,0016) and the number of values shall match the number and order of points stored in Point Coordinates Data (0066, 0016). If Track Point Index List (0066,0129) is present, measurement values are stored for a subset of points in Point Coordinates Data (0066, 0016) and the number of values shall match the number and order of point indices in Track Point Index List (0066,0129). See Section C.8.33.2.1.
>>>Track Point Index List	(0066,0129)	1C	List of indices referencing points stored in Point Coordinates Data (0066,0016) within the corresponding track for which measurement values shall be stored. Required if Measurement Values stored in Floating Point Values (0066,0125) shall be associated to only a subset of points in Point Coordinates Data (0066,0016). See Section C.8.33.2.1.
>Track Statistics Sequence	(0066,0130)	3	One statistic for one data value per track in the Track Sequence (0066,0102). See Section C.8.33.2.1 for more details. One or more Items shall be included in this Sequence.
>>Concept Name Code Sequence	(0040,A043)	1	The value (quantity) for which the statistic is a summary. Only a single Item shall be included in this Sequence.
>>>Include Table 8.8-1 “Code Sequence Macro Attributes”			DCID 7263 “Diffusion Tractography Measurement Type”
>>Modifier Code Sequence	(0040,A195)	1	Specified the statistic and modifies the Concept Name Code Sequence (0040,A0143) of this Sequence Item. Only a single Item shall be included in this Sequence.
>>>Include Table 8.8-1 “Code Sequence Macro Attributes”			DCID 7464 “General Region of Interest Measurement Modifier”
>>Measurement Units Code Sequence	(0040,08EA)	1	Units of measurement for the statistic. Only a single Item shall be included in this Sequence.
>>>Include Table 8.8-1 “Code Sequence Macro Attributes”			DCID 82 “Measurement Unit”.
>>Floating Point Values	(0066,0125)	1	A value per track in the Track Sequence (0066,0102). The number and order of values shall equal the Items in the Track Sequence (0066,0102).
>Track Set Statistics Sequence	(0066,0124)	3	Statistics derived from the values for this Track Set. One or more Items shall be included in this Sequence.
>>Include Table C.8.33-3 “Table Summary Statistics Macro Attributes”			Concept Name Code Sequence (0040,A043) DCID 7263 “Diffusion Tractography Measurement Type”
>Diffusion Acquisition Code Sequence	(0066,0133)	3	The diffusion acquisition (including post-processing) used to derive this track set. See Section C.8.33.2.2 for more details. Only a single Item shall be included in this Sequence.
>>Include Table 8.8-1 “Code Sequence Macro Attributes”			DCID 7260 “Diffusion Acquisition Value Type”
>Diffusion Model Code Sequence	(0066,0134)	1	The diffusion model used to derive this track set. See Section C.8.33.2.2 for more details. Only a single Item shall be included in this Sequence.
>>Include Table 8.8-1 “Code Sequence Macro Attributes”			DCID 7261 “Diffusion Model Value Type”
>Tracking Algorithm Identification Sequence	(0066,0104)	1	The tractography algorithms used to derive this track set. See Section C.8.33.2.2 for more details. One or more Items shall be included in this Sequence.
>>Include Table 10-19 “Algorithm Identification Macro Attributes”			Algorithm Family Code Sequence (0066,002F) DCID 7262 “Diffusion Tractography Algorithm Family”.
Referenced Instance Sequence	(0008,114A)	1C	The set of images used for tractography for all Track Sets within this Instance. One or more Items shall be included in this Sequence. Required if this Instance was created from DICOM images.
>Include Table 10-3 “Image SOP Instance Reference Macro Attributes”

C.8.33.2.1 Tractography Results Module Attribute Descriptions

This Module encodes one or more Track Sets, each of which consists of one or more Tracks, each of which is defined by one or more points. For each Track, optionally one or more measurements may be defined, either for every point or a subset of points. Measurements are described by coded type and unit. For each Track and/or Track Set, summary statistics derived from measurements may be included (whether or not the actual measurements are encoded).

When a measurement (i.e., an Item of Measurements Sequence (0066,0121) ) is encoded for every point in a track, then Floating Point Values (0066,0125) contains the corresponding values for every point. When a measurement is encoded for a subset of points, then Floating Point Values (0066,0125) contains measurement values for the points in Point Coordinates Data (0066,0016) which are referenced in Track Point Index List (0066,0129).

More than one Measurements Sequence (0066,0121) Item may be used, for example to encode different types of measurements, such as Fractional Anisotropy (FA) and Apparent Diffusion Coefficient (ADC), or to encode different components of a measurement that is a tuple, e.g., a diffusion tensor. In the latter case, which component, and which tensor, will be identified by the fully pre-coordinated code in the Concept Name Code Sequence (0040,A043).

Within one Track Set the different types of measurements or statistics must be the same for all Tracks within that set (i.e., it is not allowed to store one track to a set that does not contain a measurement of a specific type in case all other tracks within that set do).