C.8.27.6 Intravascular OCT Functional Group Macros

The following sections contain Functional Group macros specific to the Intravascular OCT IOD.

C.8.27.6.1 Intravascular OCT Frame Type Macro

Table C.8.27.6.1-1 specifies the attributes of the Intravascular OCT Frame Type Functional Group.

Table C.8.27.6.1-1INTRAVASCULAR OCT FRAME TYPE MACRO ATTRIBUTES

Attribute Name Tag Type Attribute Description
Intravascular OCT Frame Type Sequence (0052,0025) 1 Identifies characteristics of this frame. Only a single Item shall be included in this sequence.
>Frame Type (0008,9007) 1 Type of Frame. A multi-valued attribute analogous to the Image Type (0008,0008). Enumerated Values and Defined Terms are the same as those for the four values of the Image Type (0008,0008) attribute, except that the value MIXED is not allowed. See section C.8.27.2.1.

C.8.27.6.2 Intravascular Frame Content Macro

Table C.8.27.6.2-1 specifies the attributes of the Intravascular Frame Content Functional Group.

Table C.8.27.6.2-1INTRAVASCULAR FRAME CONTENT MACRO ATTRIBUTES

Attribute Name Tag Type Attribute Description
Intravascular Frame Content Sequence (0052,0027) 1 A sequence that describes a general description of this image or frame. Only a single Item shall be included in this sequence.
>Intravascular Longitudinal Distance (0052,0028) 1C Longitudinal distance in millimeters between this frame and the previous acquired frame. Positive values indicate movement is from Distal to Proximal (pull back). Negative values indicate movement is from Proximal to Distal (push forward). Required if Intravascular Acquisition (0018,3100) equals MEASURED.
>Seam Line Location (0052,0033) 2C Clockwise rotational orientation (in degrees) at which the seam line in the frame is displayed, relative to vertical (zero degrees). Required if Presentation Intent Type (0008,0068) equals FOR PRESENTATION.

C.8.27.6.3 Intravascular OCT Frame Content Macro

Table C.8.27.6.3-1 specifies the attributes of the Intravascular OCT Frame Content Functional Group.

Table C.8.27.6.3-1INTRAVASCULAR OCT FRAME CONTENT MACRO ATTRIBUTES

Attribute Name Tag Type Attribute Description
Intravascular OCT Frame Content Sequence (0052,0029) 1 A sequence that describes a general description of this image or frame. Only a single Item shall be included in this sequence.
>OCT Z Offset Correction (0052,0030) 1 The amount to shift the frame along the axial direction, in pixels, to correct for interferometer path-length mismatch. See section C.8.27.6.3.1 for further explanation.
>Seam Line Index (0052,0036) 1 The A-line number (zero index) that coincides with the seam line as indicated with the First A-line Location (0052,0034) attribute.
>Number of Padded A-lines (0052,0038) 1C The number of padded A-lines contained in the FOR PROCESSING image frame. Required if the FOR PROCESSING image contains padded A-lines. See section C.8.27.6.3.2 for further explanation.

C.8.27.6.3.1 OCT Z Offset Correction

OCT Z Offset Correction (0052,0030) specifies the number of pixels to shift the A-lines of the frame to correct for the path length difference between the OCT Sample arm and Reference arm (in air). A positive value of Z Offset correction means pixels are shifted further away from the catheter optics. A negative value of Z Offset correction means pixels are shifted closer to the catheter optics. See Figure C.8.27-2

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Figure C.8.27-2 OCT Z Offset Correction Example

C.8.27.6.3.2 A-line Padding

Padded A-lines shall not be used in FOR PRESENTATION frames. Padded A-lines shall only be encoded in the high order rows of the FOR PROCESSING frame and shall be contiguous. Padded A-lines may contain arbitrary pixel values.