FFF.2.1.1.4 Examples

In the two following examples, the Image Modality acquires a multi-frame image of the coronary arteries lasting 4 seconds, at 30 frames per second.

Simultaneously, the same modality acquires two channels of ECG from a 2-Lead ECG (the first channel on Lead I and the second on Lead II) starting one second before the image acquisition starts, and lasting 5 seconds, with a sampling frequency of 300 Hz on 16 bits signed encoding, making up a number of 1500 samples per channel. The first ECG sample is 10 ms after the nominal start time of the ECG acquisition. Both ECG channels are sampled simultaneously. The time skew of both channels is 0 ms.

[pic]

Figure FFF.2.1-2Example of ECG Recording at Acquisition Modality

FFF.2.1.1.4.1 Enhanced XA image without cardiac synchronization

In this example, the Enhanced XA image does not contain information of the cardiac cycle phases.

The attributes that define the two different SOP Instances (Enhanced XA and General ECG) of this example are described in the following figures:

ENHANCED XA SOP INSTANCE

Study Instance UID (0020,000D) = UID “A”
Modality (0008,0060) = XA
Synchronization Trigger (0018,106A) = NO TRIGGER
Acquisition Time Synchronized (0018,1800) = Y
Referenced Instance Sequence (0008,114A)
Item 1
>Referenced SOP Class UID (0008,1150)
Series Instance UID (0020,000E) = UID “F”
Modality (0008,0060) = ECG
Synchronization Frame of Reference UID (0020,0200) = UID “C”
Synchronization Trigger (0018,106A) = NO TRIGGER
Acquisition Time Synchronized (0018,1800) = Y
SOP Instance UID (0008,0018) = UID “E”
Referenced Instance Sequence (0008,114A)
Item 1
>Referenced SOP Class UID (0008,1150) = 1.2.840.10008.5.1.4.1.1.12.1.1
>Referenced SOP Instance UID (0008,1155) = UID “D”
>Purpose of Reference Code Sequence (0040,A170)
Item 1
Item 1 Only one ECG Multiplex Group
>Multiplex Group Time Offset (0018,1068) = 10
>Waveform Originality (003A,0004) = ORIGINAL
>Number of Waveform Channels (003A,0005) = 2
>Number of Waveform Samples (003A,0010) = 1500
>Sampling Frequency (003A,001A) = 300
>Channel Definition Sequence (003A,0200)
Item 1
>Waveform Sample Interpretation (5400,1006) = SS

Figure FFF.2.1-3Attributes of ECG Recording at Acquisition Modality

FFF.2.1.1.4.2 Enhanced XA image with cardiac synchronization

In this example, the heart rate is 75 beats per minute. As the image is acquired during a period of four seconds, it contains five heartbeats.

The ECG signal is analyzed to determine the R-peaks and to relate them to the angiographic frames. Thus the Enhanced XA image contains information of this relationship between the ECG signal and the frames.

[pic]

Figure FFF.2.1- 4 Example of ECG information in the Enhanced XA image

The attributes that define the two different SOP Instances (Enhanced XA and General ECG) of this example are described in the figures of the previous example, in addition to the attributes described in the following figures:

ENHANCED XA SOP INSTANCE

Cardiac Synchronization Technique (0018,9037) = REALTIME
Cardiac Signal Source (0018,9085) = ECG
Cardiac RR Interval Specified (0018,9070) = 800
Intervals Acquired (0018,1083) = 5
Intervals Rejected (0018,1084) = 0
Per-Frame Functional Groups Sequence (5200,9230)    
  Item i     Frame “i”
    >Cardiac Synchronization Sequence (0018,9118)    
      Item 1      
       
Frame of Reference Synchronization C.7.4.2 Specifies that the image acquisition is time synchronized with the ECG acquisition. Will have the same content as the General ECG SOP Instance.
Image Enhanced XA/XRF Image C.8.19.2 Specifies the date and time of the image acquisition.

Table FFF.2. 1-13 ENHANCED XA IMAGE FUNCTIONAL GROUP MACROS

Functional Group Macro PS 3.3 Reference Usage
Frame Content C.7.6.16.2.2 Provides timing information to correlate each frame to any externally recorded waveform.

FFF.2.1.2.1.3.1.1 Synchronization Module Recommendations

This Module is used to document the synchronization of the two modalities.

Table FFF.2.1-14 SYNCHRONIZATION MODULE Recommendations

Attribute Name Tag Comment
Synchronization Frame of Reference UID (0020,0200) The UTC Synchronization UID “1.2.840.10008.15.1.1” is used in this case.
Synchronization Trigger (0018,106A) The value “NO TRIGGER” is used for the case of time synchronization via NTP.
Acquisition Time Synchronized (0018,1800) The value “Y” is used in this scenario.
Time Source (0018,1801) The same value as in the related General ECG SOP Instance is used in this scenario.
Time Distribution Protocol (0018,1802) The value “NTP” is used in this scenario.
NTP Source Address (0018,1803) The same value as in the related General ECG SOP Instance is used in this scenario.

FFF.2.1.2.1.3.1.2 Enhanced XA/XRF Image Module Recommendations

This module includes the acquisition date and time of the image, which is in the same time basis as the acquisition date and time of the ECG in this scenario.

FFF.2.1.2.1.3.1.3 Frame Content Macro Recommendations

In this scenario the timing information is important to correlate each frame to any externally recorded waveform.

Table FFF.2.1-15 FRAME CONTENT MACRO Recommendations

Attribute Name Tag Comment
Frame Content Sequence (0020,9111)
>Frame Reference Datetime (0018,9151) Exact date and time taken from the synchronized clock.
>Frame Acquisition Datetime (0018,9074) Exact date and time taken from the synchronized clock.

FFF.2.1.2.1.3.2 Waveform Object

The ECG recording system will take care of filling in the waveform-specific contents in the General ECG SOP Instance. This section will address only the specifics for attributes related to synchronization.

Table FFF.2. 1-16 Waveform IOD Modules

IE Module PS 3.3 Reference Usage
Frame of Reference Synchronization C.7.4.2 Specifies that the ECG acquisition is time synchronized with the image acquisition. Will have the same content as the Enhanced XA SOP Instance. See section FFF.2.1.2.1.3.1.1.
Waveform Waveform Identification C.10.8 Provides timing information to correlate the waveform data to any externally recorded image.

FFF.2.1.2.1.3.2.1 Waveform Identification Recommendations

The usage of this module is recommended to relate the acquisition time of the waveform data to the related image(s).

Table FFF.2.1-18 WAVEFORM IDENTIFICATION MODULE Recommendations

Attribute Name Tag Comment
Acquisition Datetime (0008,002A) Exact start of the waveform acquisition: taken from synchronized clock.

FFF.2.1.2.1.4 Example

In this example, there are two modalities that are synchronized with an external clock via NTP. The Image Modality acquires three multi-frame images within the same Study and same Series. Simultaneously, the Waveform Modality acquires the ECG non-stop during the same period, leading to one single Waveform SOP Instance on a different Study.

In this example, there is no UID referencing capability between the two modalities.

[pic]

Figure FFF.2.1-7Example of Multi-modality Waveform Synchronization

The attributes that define the relevant content in the two different SOP Instances (Enhanced XA and General ECG) are described in the following figure:

ENHANCED XA SOP INSTANCES

Study Instance UID (0020,000D) = UID “A”
Series Instance UID (0020,000E) = UID “B”
Modality (0008,0060) = XA
Synchronization Frame of Reference UID (0020,0200) = 1.2.840.10008.15.1.1
Synchronization Trigger (0018,106A) = NO TRIGGER
Acquisition Time Synchronized (0018,1800) = Y
Time Source (0018,1801) = Clock System ID
Time Distribution Protocol (0018,1802) = NTP
NTP Source Address (0018,1803) = aaa.bbb.ccc.ddd
SOP Instance UID (0008,0018) = UID “D1”, “D2” and “D3” resp.

GENERAL ECG SOP INSTANCE

Study Instance UID (0020,000D) = UID “E”
Series Instance UID (0020,000E) = UID “F”
Modality (0008,0060) = ECG
Synchronization Frame of Reference UID (0020,0200) = 1.2.840.10008.15.1.1
Synchronization Trigger (0018,106A) = NO TRIGGER
Acquisition Time Synchronized (0018,1800) = Y
Time Source (0018,1801) = Clock System ID
Time Distribution Protocol (0018,1802) = NTP
NTP Source Address (0018,1803) = aaa.bbb.ccc.ddd
SOP Instance UID (0008,0018) = UID “H”

Figure FFF.2.1-8Attributes of Multi-modality Waveform NTP Synchronization