C. Image Data Type Macro

Table C. specifies the attributes of the Image Data Type Functional Group macro.


Attribute Name Tag Type Attribute Description
Image Data Type Sequence (0018,9807) 1 Identifies the data type characteristics of this frame. Only a single Item shall be included in this sequence.
>Data Type (0018,9808) 1 Identification of the data type of a frame. See C. for Defined Terms and further explanation.
>Aliased Data Type (0018,980B) 1 Indicates whether this data type is “aliased”. Enumerated Values: YES = data are aliased values NO = data are not aliased values See C. for further explanation.

C. Data Type

Data Type (0018,9808) indicates the data type of an image frame. Table C. lists Defined Terms for this value.

Table C.


Defined Term Name Defined Term Description
TISSUE_INTENSITY Tissue intensity typically displayed as grayscale (e.g. B-mode)
TISSUE_VELOCITY Velocity (Doppler shifts) of tissue
FLOW_VELOCITY Velocity (Doppler shifts) of blood flow
FLOW_POWER Power contained in the Doppler signal
FLOW_VARIANCE Statistical variance of blood velocity relative to mean
ELASTICITY Scalar value related to the elastic properties of the tissue
PERFUSION Scalar value related to the volume of blood perfusing into tissue
SOUND_SPEED Speed of sound in tissue
ATTENUATION Reduction in strength of ultrasound signal as the wave traverses through the medium

C. Aliased Data Type

Some data types require special treatment when interpolating data values whose type is “aliased”, such as FLOW_VELOCITY when derived from discrete data samples as is done for PW Doppler or sampled CW Doppler. Values of these types are “cyclical” in that the maximum value should be considered adjacent to the minumum value in any interpolation algorithm. Aliased Data Type (0018,980B) indicates whether modular arithmetic is necessary for the associated data type.

Note: For example, when Data Type (0018,9808) is FLOW_VELOCITY, Aliased Data Type (0018,980B) should be set to YES indicating that an interpolation algorithm should support aliased data. When several FLOW_VELOCITY values near the maximum or minimum are interpolated, this algorithm should produce a value near the maximum or minimum. It would be incorrect to use an interpolation algorithm such as the arithmetic mean, which would erroneously produce a result near the mid-point of the range.