C.7.6.16.2.2 Frame Content Macro

Table C.7.6.16-3 specifies the attributes of the Frame Content Functional Group macro.

This Functional Group Macro may only be part of the Per-frame Functional Groups Sequence (5200,9230) attribute.

Table C.7.6.16-3FRAME CONTENT MACRO ATTRIBUTES

Attribute Name Tag Type Attribute Description
Frame Content Sequence (0020,9111) 1 Identifies general characteristics of this frame. Only a single Item shall be included in this sequence.
>Frame Acquisition Number (0020,9156) 3 A number identifying the single continuous gathering of data over a period of time that resulted in this frame.
>Frame Reference DateTime (0018,9151) 1C The point in time that is most representative of when data was acquired for this frame. See C.7.6.16.2.2.1 and C.7.6.16.2.2.2 for further explanation. Note: The synchronization of this time with an external clock is specified in the synchronization Module in Acquisition Time synchronized (0018,1800). Required if Frame Type (0008,9007) Value 1 of this frame is ORIGINAL. May be present otherwise.
>Frame Acquisition DateTime (0018,9074) 1C The date and time that the acquisition of data that resulted in this frame started. See C.7.6.16.2.2.1 for further explanation. Required if Frame Type (0008,9007) Value 1 of this frame is ORIGINAL. May be present otherwise.
>Frame Acquisition Duration (0018,9220) 1C The actual amount of time [in milliseconds] that was used to acquire data for this frame. See C.7.6.16.2.2.1 and C.7.6.16.2.2.3 for further explanation. Required if Frame Type (0008,9007) Value 1 of this frame is ORIGINAL. May be present otherwise.
>Cardiac Cycle Position (0018,9236) 3 Description of the position in the cardiac cycle that is most representative of this frame. Defined Terms: END_SYSTOLE END_DIASTOLE UNDETERMINED
>Respiratory Cycle Position (0018,9214) 3 Description of the position in the respiratory cycle that is most representative of this frame. Defined Terms: START _RESPIR END_RESPIR UNDETERMINED
>Dimension Index Values (0020,9157) 1C Contains the values of the indices defined in the Dimension Index Sequence (0020,9222) for this multi-frame header frame. The number of values is equal to the number of Items of the Dimension Index Sequence and shall be applied in the same order. See section C.7.6.17.1 for a description. Required if the value of the Dimension Index Sequence (0020,9222) exists.
>Temporal Position Index (0020,9128) 1C Ordinal number (starting from 1) of the frame in the set of frames with different temporal positions. Required if the value of SOP Class UID (0008,0016) equals “1.2.840.10008.5.1.4.1.1.130”. May be present otherwise. See C.7.6.16.2.2.6.
>Stack ID (0020,9056) 1C Identification of a group of frames, with different positions and/or orientations that belong together, within a dimension organization. See C.7.6.16.2.2.4 for further explanation. Required if the value of SOP Class UID (0008,0016) equals “1.2.840.10008.5.1.4.1.1.130”. May be present otherwise. See C.7.6.16.2.2.7.
>In-Stack Position Number (0020,9057) 1C The ordinal number of a frame in a group of frames, with the same Stack ID Required if Stack ID (0020,9056) is present. See section C.7.6.16.2.2.4 for further explanation.
>Frame Comments (0020,9158) 3 User-defined comments about the frame.
>Frame Label (0020,9453) 3 Label corresponding to a specific dimension index value. Selected from a set of dimension values defined by the application. This attribute may be referenced by the Dimension Index Pointer (0020,9165) attribute in the Multi-frame Dimension Module. See C.7.6.16.2.2.5 for further explanation.

C.7.6.16.2.2.1 Timing Parameter Relationships

Figure C.7.6.16-2 shows the relationships among the various timing parameters used.

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Figure C.7.6.16-2Relationship of Timing Related Attributes

C.7.6.16.2.2.2 Frame Reference DateTime

The Frame Reference DateTime (0018,9151) is used to indicate the point in time that is most representative for that specific frame.

Notes: 1. For example, in the case of MR it might be the time of acquisition of the data for the k y =0 line in k-space (the central Fourier segment).

2. For cardiac gated acquisitions the choice of the Frame Reference DateTime (0018,9151) is influenced by the Nominal Cardiac Trigger Delay Time (0020,9153). For respiratory gated acquisitions the choice of the Frame Reference DateTime (0018,9151) is influenced by the Nominal Respiratory Trigger Delay Time (0020,9255).

C.7.6.16.2.2.3 Frame Acquisition Duration

The Frame Acquisition Duration (0018,9220) is used to indicate the duration of the acquisition related to this frame.

For SOP Instances or Concatenations of the Enhanced PET Image Storage SOP Class (1.2.840.10008.5.1.4.1.1.130) the Frame Acquisition Duration (0018,9220) is the sum of the portion of each cycle during which data contributing to this frame has actually been acquired for all of the cardiac or respiratory cycles of a gated acquisition (i.e. if Cardiac Synchronization Technique (0018,9037) equals other than NONE, and/or if Respiratory Motion Compensation Technique (0018,9170) equals other than NONE).

C.7.6.16.2.2.4 Concatenations and Stacks

Due to implementation specific reasons (such as maximum object size) the information of a multi-frame image may be split into more than one SOP Instance. These SOP Instances form together a Concatenation. This is a group of SOP Instances within a Series that is uniquely identified by the Concatenation UID (0020,9161).

The Dimension Index Sequence (0020,9222) for each SOP Instance with the same Concatenation UID (0020,9161) shall contain exactly the same tags and values.

In a Concatenation the Dimension Index Sequence (0020,9222) items of the Shared Functional Groups (5200,9229) shall be identical and have the same values for all individual SOP Instances. The items of the Per-frame Functional Groups (5200,9230) shall be identical for all individual SOP Instances but the values may change per frame. For all other Attributes of all the Modules of the IOD, the same Attributes shall be present and the values shall be identical, with the exception of the following Attributes:

Note: The intent of Concatenations is to split what might have been encoded in a single SOP Instance into smaller fragments for more convenient storage or transmission. All the multiple SOP Instances of a Concatenation should be able to be assembled into a valid single SOP Instance. Hence it is not permitted to change such Attributes as Photometric Interpretation (0028,0004), Rows (0028,0010), Columns (0028,0011), etc.

Stacks describe application-specific groups of frames that have a geometric relationship. Stacks have a Stack ID (0020,9056) that contains a descriptive name that identifies the stack. A Stack ID (0020,9056) may be re-used in another SOP Instance even outside a concatenation. The value of Stack ID (0020,9056) is unique within the scope of a particular Dimension Organization UID (0020,9164) if present, otherwise it is unique within the scope of a particular Concatenation UID (0020,9161). See Figure C7.6.16-3 for an example.

[pic] Figure C.7.6.16-3 Identifying attributes for Concatenation, SOP Instances, Frames and Stacks

Each frame in a stack has an In-Stack Position Number (0020,9057) that is the ordinal number (starting from 1) of the frame within the set of frames with the same Stack ID (0020,9056), see Figure C.7.6.16-4 for an example.

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Figure C.7.6.16-4 Example of multiple stacks

In order to allow interoperable operations on stacks, 2 different frames with the same Stack ID (0020,9056) can only have the same In-Stack Position Number (0020,9057) if they have the same values for the following attributes:

  1. Dimension Organization UID (0020,9164) or if absent Concatenation UID (0020,9161) to qualify the Stack ID

  2. Image Position (Patient) (0020,0032)

  3. Image Orientation (Patient) (0020,0037)

  4. Rows (0028,0010) ( first value of Pixel Spacing (0028,0030) (= field of view in the row direction)

  5. Columns (0028,0011) ( second value of Pixel Spacing (0028,0030) (= field of view in the column direction)

  6. Slice Thickness (0018,0050)

C.7.6.16.2.2.5 Frame Label

The Frame Label attribute (0020,9453) can be used to label frames that need to be handled as a group in application. The Dimension Index Pointer (0020,9165) from the Dimension Module may point to this attribute if it is the base of a dimension.

C.7.6.16.2.2.6 Temporal Position Index and Stack ID in PET images

For PET Dynamic images, i.e. images in which Image Type (0008,0008) Value 3 is DYNAMIC, Temporal Position Index is used to distinguish between the multiple acquisitions of the same anatomical area. Similarly, the frames that result from one acquisition over the anatomic area shall be contained in one stack. Thus, for Dynamic images, Temporal Position Index (0020,9128), Stack ID (0020,9056), and In-Stack Position Number (0020,9057) shall be used as three of the dimensions of the image, in that order.

Figure C.7.6.16-4b describes the usage for a PET dynamic image.

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Figure C.7.6.16-4bPET dynamic frame organization

C.7.6.16.2.2.7 Stack ID usage in PET static, whole body and gated images

For static and whole body PET images, a single Stack ID (0020,9056) is used to group all of the transverse slices over the entire imaged volume together. That is, a single Stack ID (0020,9056) is used no matter how many acquisition bed positions are involved. In-Stack Position Number (0020,9057) is then used as the spatial dimension index. When rectangular sagittal, coronal or oblique images are created from these, a single Stack ID (0020,9056) is again used.

Similarly, in cardiac or respiratory gated images, the entire volume is again identified by a single Stack ID (0020,9056), and In-Stack Position Number (0020,9057) is the spatial dimension index. The time dimension is indicated by one of the timing attributes, such as trigger delay time or respiratory phase.