FFF.2.1.6 Acquisitions with Contrast

This section provides information on the encoding of the presence and type of contrast bolus administered during the X-Ray acquisition.

FFF.2.1.6.1 User Scenario

The user performs image acquisition with injection of contrast agent during the X-Ray acquisition. Some frames are acquired without contrast, some others with contrast.

The type of contrast agent can be radio-opaque (e.g., iodine) or radio-transparent (e.g., CO2).

The information of the type of contrast and its presence or absence in the frames can be used by post-processing applications to set up e.g., vessel detection or image quality algorithms automatically.

FFF.2.1.6.2 Encoding outline

The Enhanced XA SOP Class encodes the characteristics of the contrast agent(s) used during the acquisition of the image, including the type of absorption (radio-opaque or radio-transparent).

The Enhanced XA SOP Class also allows encoding the presence of contrast in a particular frame or set of frames, by encoding the Contrast/Bolus Usage per-frame.

FFF.2.1.6.3 Encoding details

This section provides detailed recommendations of the key attributes to address this particular scenario.

Table FFF.2. 1-46 ENHANCED X-RAY ANGIOGRAPHIC IMAGE IOD MODULES

IE Module PS 3.3 Reference Usage
Image Enhanced Contrast/Bolus C.7.6.4b Specifies the characteristics of the contrast agent(s) administered.

Table FFF.2. 1-47 ENHANCED XA IMAGE FUNCTIONAL GROUP MACROS

Functional Group Macro PS 3.3 Reference Usage
Contrast/Bolus Usage C.7.6.16.2.12 Specifies the presence of contrast in the frame(s).

FFF.2.1.6.3.1 Enhanced Contrast/Bolus Module Recommendations

The usage of this module is recommended to specify the type and characteristics of the contrast agent administered.

FFF.2.1.6.3.2 Contrast/Bolus Usage Macro Recommendations

The usage of this macro is recommended to specify the characteristics of the contrast per-frame.

Table FFF.2.1-48 CONTRAST/BOLUS USAGE MACRO Recommendations

Attribute Name Tag Comment
Contrast/Bolus Usage Sequence (0018,9341) One item per contrast agent used in this frame.
>Contrast/Bolus Agent Number (0018,9337) Contains the internal number of the agent administered as specified in the Enhanced Contrast/Bolus Module.
>Contrast/Bolus Agent Administered (0018,9342) The value “YES” indicates that the contrast may be visible on the frame, but not necessarily if the frame is acquired before the contrast reaches the imaged region.
>Contrast/Bolus Agent Detected (0018,9343) The value “YES” is used if the contrast is visible on that particular frame. Note that it is not expected to be YES if Contrast/Bolus Agent Administered (0018,9342) equals NO.

FFF.2.1.6.4 Example

In this example, the user starts the X-Ray acquisition at 4 frames per second at 3:35pm. After one second the user starts the injection of 45 milliliters of contrast media Iodipamide (350 mg/ml Cholographin (Bracco)) at a flow rate of 15 ml/sec during three seconds, in intra-arterial route. When the injection of contrast agent is finished, the user continues the X-Ray acquisition for two seconds until wash out of the contrast agent.

There could be two ways to determine the presence of contrast agent on the frames:

  1. The injector is connected to the X-Ray acquisition system, the presence of contrast agent is determined based on the injector start/stop signals and a preconfigured delay to allow the contrast to reach the artery of interest, or

  2. The X-Ray system processes the images in real time and detects the presence or absence of contrast agent on the images.

In this example, the image acquired contains 25 frames: From frames 5 to 17, the contrast is being injected. From frames 8 to 23, the contrast is visible on the pixel data.

The figure below shows the attributes of this example in a graphical representation of the multi-frame acquisition.

[pic]

Figure FFF.2.1-29Example of contrast agent injection

Below are the encoded values of the key attributes of this example:

Contrast/Bolus Agent Sequence (0018,0012)    
  Item 1     Contrast agent 1
    >Code Value (0008,0100) = C-B0318
    >Coding Scheme Designator (0008,0102) = SRT
    >Code Meaning (0008,0104) = Iodipamide
    >Contrast/Bolus Agent Number (0018,9337) = 1
    >Contrast/Bolus Administration Route Sequence (0018,0014)  
      Item 1    
        >>Code Value (0008,0100)
      Item 1    
        >>Code Value (0008,0100)
    >Contrast/Bolus Ingredient Concentration (0018,1049) = 350
    >Contrast/Bolus Ingredient Opaque (0018,9425) = YES
    >Contrast Administration Profile Sequence (0018,9340)  
      Item 1   Administered phase 1
       
  Items 1 to 4     Frames 1 to 4
    >Contrast/Bolus Usage Sequence (0018,9341)    
      Item 1    
        >>Contrast/Bolus Agent Number
    >Contrast/Bolus Usage Sequence (0018,9341)  
      Item 1    
        >>Contrast/Bolus Agent Number
    >Contrast/Bolus Usage Sequence (0018,9341)  
      Item 1    
        >>Contrast/Bolus Agent Number
    >Contrast/Bolus Usage Sequence (0018,9341)  
      Item 1    
       
Image XA/XRF Acquisition C.8.19.3 Specifies average values for the X-Ray generation techniques.

Table FFF.2. 1-50 ENHANCED XA IMAGE FUNCTIONAL GROUP MACROS

Functional Group Macro PS 3.3 Reference Usage
Frame Content C.7.6.16.2.2 Specifies the frame duration.
X-Ray Frame Acquisition C.8.19.6.8 Specifies the kVp and mA per frame.

FFF.2.1.7.3.1 XA/XRF Acquisition Module Recommendations

The usage of this module is recommended to specify the average values of time, voltage and current applied during the acquisition of the multi-frame image.

It gives general information of the X-Ray radiation during the acquisition of the image. In case of dynamic acquisitions, this module is not sufficient to estimate the radiation per body area and additional per-frame information is needed.

Table FFF.2.1-51 XA/XRF ACQUISITION MODULE Recommendations

Attribute Name Tag Comment
KVP (0018,0060) Recommended in this scenario.
Radiation Setting (0018,1155) The values “SC” and “GR” give a rough indication of the level of the dose such as “low” or “high”, nevertheless they are used more for quality assurance and/or display purposes, not for estimation of radiation values.
X-Ray Tube Current in mA (0018,9330) Recommended in this scenario.
Exposure Time in ms (0018,9328) Recommended in this scenario.
Exposure in mAs (0018,9332) Recommended in this scenario.
Average Pulse Width (0018,1154) Recommended in this scenario.
Radiation Mode (0018,115A) The value of this attribute is used more for quality assurance and/or display purposes, not for estimation of radiation values.

Note that the three attributes X-Ray Tube Current in mA (0018,9330), Exposure Time in ms (0018,9328) and Exposure in mAs (0018,9332) are mutually conditional to each other but all three may be present. In this scenario it is recommended to include the three attributes.

FFF.2.1.7.3.2 Frame Content Macro Recommendations

The usage of this macro is recommended to specify the duration of each frame of the multi-frame image.

Note that this macro is allowed to be used only in a per-frame context, even if the pulse duration is constant for all the frames.

FFF.2.1.7.3.3 X-Ray Frame Acquisition Macro Recommendations

The usage of this macro is recommended to specify the values of voltage (kVp) and current (mA) applied for the acquisition of each frame of the multi-frame image.

If the system can provide only average values of kVp and mA, the usage of the X-Ray Frame Acquisition macro is not recommended, only the XA/XRF Acquisition Module is recommended.

If the system predefines the values of the kVp and mA to be constant during the acquisition, the usage of the X-Ray Frame Acquisition macro in a shared context is recommended in order to indicate that the value of kVp and mA is identical for each frame.

If the system is able to change dynamically the kVp and mA during the acquisition, the usage of the X-Ray Frame Acquisition macro in a per-frame context is recommended.

Table FFF.2.1-52 X-RAY FRAME ACQUISITION MACRO Recommendations

Attribute Name Tag Comment
Frame Acquisition Sequence (0018,9417) Recommended in this scenario if both values kVp and mA are known for each frame.

FFF.2.1.7.4 Example

For more details, refer to the section FFF.1.4