DICOM PS3.3 2019c - Information Object Definitions

C.8.16 Common CT, MR and US Descriptions

This section contains descriptions of Macros and Attributes used in Modules and Functional Group Macros that are common to the Enhanced CT Image, Enhanced MR Images, MR Spectroscopy and Enhanced US Volume IODs.

C.8.16.1 Image Type and Frame Type

Image Type (0008,0008) and associated Image Type related Attributes provide a high level description of a multi-frame SOP Instance. These Attributes describe properties that provide key summary information to users of the SOP Instance. Image Type (0008,0008) contains the highest level summary of what is in the SOP Instance.

Frame Type (0008,9007) mirrors the corresponding Image Type Attribute and applies to the frame level rather than to the image level.

If more than one value is used by the set of frames for a given Frame Type (0008,9007) Attribute value or associated Attribute value then the corresponding value of Image Type (0008,0008) or associated Attribute shall contain a value of MIXED. This indicates that a mixed set of values exists within the multi-frame SOP Instance.

The value MIXED shall only be used in Image Type (0008,0008) when the corresponding values for the individual frames are not equal. When a value of an Attribute is equal for all frames, the same value shall be used for the corresponding value of Image Type (0008,0008). Values 2 and 3 of Image Type (0008,0008) are an exception to the rule for MIXED: Values 2 and 3 may never have the value of MIXED as described in Section C.8.16.1.2 and Section C.8.16.1.3.

Image Type (0008,0008) and Frame Type (0008,9007) shall consist of four values.

C.8.16.1.1 Pixel Data Characteristics

Value 1 of Image Type (0008,0008) and Frame Type (0008,9007) shall use one of the following Enumerated Values from Table C.8-127.

Value 1 of Image Type (0008,0008) and Value 1 of Frame Type (0008,9007) shall not be zero length.

Table C.8-127. Image Type and Frame Type Value 1

Enumerated Value Name

Enumerated Value Description

ORIGINAL

An image or frame is original if its pixel data was directly reconstructed from the original data that is obtained from the sensors of the imaging equipment, Image Type (0008,0008) Value 4 is NONE, and Volume Based Calculation Technique (0008,9207) is NONE.

Note

  1. For MR, original data is data directly reconstructed from k-space data.

  2. For CT, original frames are those directly reconstructed from projection data.

DERIVED

An image or frame is derived if its pixel data was calculated from original or other derived pixel data (i.e., it is not original).

MIXED

Used only as a value in Image Type (0008,0008) if frames within the SOP Instance contain different values for Value 1 in their Frame Type (0008,9007).


C.8.16.1.2 Patient Examination Characteristics

Value 2 for Image Type (0008,0008) and Frame Type (0008,9007) follows the standard definition and shall have the following Enumerated Value from Table C.8-128.

Value 2 of Image Type (0008,0008) and Value 2 of Frame Type (0008,9007) shall not be zero length.

Table C.8-128. Image Type and Frame Type Value 2

Enumerated Value Name

Enumerated Value Description

PRIMARY

See Section C.7.6.1.1.2


C.8.16.1.3 Image Flavor

Value 3 is an overall representation of the image type. This value may be a summary of several other Attributes or a duplication of one of the other Attributes to indicate the most important aspect of this image. Value 3 Image Flavor is to be used with Value 4 Derived Pixel Contrast to indicate the nature of the image set.

Note

For example Value 3 = DIFFUSION together with Value 4 = NONE indicates that the image set was originally collected for DIFFUSION.

If Value 3 = DIFFUSION together with Value 4 = DIFFUSION this indicates that the object contains DIFFUSION weighted post processed images.

Value 3 of Image Type (0008,0008) shall not be zero length.

Value 3 of Frame Type (0008,9007) may have the same value as found in Value 3 of Image Type (0008,0008), or may have a different value.

The Attribute value may not be MIXED as this value needs to be a summary of the primary purpose of the images, whether the frames have the same value or not.

Table C.8-129 specifies the Defined Terms for Value 3 for Image Type (0008,0008) and Frame Type (0008,9007) that are common to CT and MR. Additional Defined Terms are defined in the modality-specific Module and Macro definitions.

Table C.8-129. Image Type and Frame Type Value 3 Common

Defined Term Name

Defined Term Description

ANGIO

Collected for the purpose of angiography

CARDIAC

Images of the heart

CARDIAC_GATED

Cardiac gated images, other than of the heart

CARDRESP_GATED

Cardiac and respiratory gated images

DYNAMIC

An image in which the same anatomical volume is imaged at multiple times in order to capture images of a non-cyclic, time varying event. For example, imaging of the uptake of a tracer or contrast in a specific organ over time.

Note

This is different from gating techniques, in which the same anatomical volume is imaged during some portion of a cyclic event, e.g., inspiration or R-R Interval.

FLUOROSCOPY

Real-time collection of single slices (e.g., CT or MR Fluoroscopy)

LOCALIZER

Collected for the purpose of planning other images.

MOTION

Collected for looking at body motion

PERFUSION

Collected for the purposes of perfusion calculations.

PRE_CONTRAST

Collected before contrast was administered

POST_CONTRAST

Collected during or after contrast was administered

RESP_GATED

Respiratory gated images

REST

Cardiac rest image set

STATIC

A group of frames at varying spatial locations acquired at the same time.

STRESS

Cardiac stress image set

VOLUME

Set of frames that define a regularly sampled volume

NON_PARALLEL

Set of frames that are not parallel

PARALLEL

Set of frames that are parallel but do not constitute a regularly sampled volume

WHOLE_BODY

A group of frames of the whole body; the frames may be acquired at various times (as distinct from STATIC).


C.8.16.1.4 Derived Pixel Contrast

Value 4 shall be used to indicate derived pixel contrast - generally, contrast created by combining or processing images with the same geometry. Value 4 shall have a value of NONE when Value 1 is ORIGINAL.

Value 4 may have the value QUANTITY if the derived pixel contrast is described in the Quantity Definition Sequence (0040,9220) of the Real World Value Mapping Functional Group Macro.

Note

If more than one of the following derived types is applicable, then it is up to the generating application to specify the value that best characterizes the derived image.

Value 4 of Image Type (0008,0008) and Value 4 of Frame Type (0008,9007) shall not be zero length unless the SOP Class UID is "1.2.840.10008.5.1.4.1.1.2.2" or "1.2.840.10008.5.1.4.1.1.4.4" or "1.2.840.10008.5.1.4.1.1.128.1" (Legacy Converted).

Table C.8-130 specifies the Defined Terms for Value 4 for Image Type (0008,0008) and Frame Type (0008,9007) that are common to CT and MR. Additional Defined Terms are defined in the modality-specific Module and Macro definitions.

Table C.8-130. Image Type and Frame Type Value 4 Common

Defined Term Name

Defined Term Description

ADDITION

Created through Pixel by pixel addition operation

DIVISION

Created through Pixel by pixel division operation

MASKED

Created through Pixel by pixel masking operation

MAXIMUM

Created through Pixel by Pixel maximum operation

MEAN

Created through Pixel by pixel mean operation

MINIMUM

Created through Pixel by Pixel minimum operation

MULTIPLICATION

Created through Pixel by pixel multiplication operation

RESAMPLED

Pixels have been spatially re-sampled, e.g., MPR

STD_DEVIATION

Standard Deviation

SUBTRACTION

Created through Pixel by pixel subtraction operation

NONE

Not a calculated image

QUANTITY

Derived pixel values are a quantity described by Quantity Definition Sequence (0040,9220) of the Real World Value Mapping Functional Group Macro.

MIXED

Used only as value in Image Type (0008,0008) if frames within the image SOP Instance contain different values for value 4 in their Frame Type (0008,9007) Attribute.


DICOM PS3.3 2019c - Information Object Definitions