Knowledge Base

Flow

Aim

To obtain a relative measure of body fluid movements in a section of a blood vessel or the gut.

To Open the Flow Screen

Choose Acquisition > Flow.

Notes

• In DanioScope, Flow measures the percentage of the area of interest that changes its gray scale value per video frame. The higher the flow rate in a gut or blood vessel, the higher this percentage. Note that Flow does not measure flow rate in physical units (like volume or mass per time unit).
• Important: Make sure that the video is in focus. If the image is not in focus, Flow is generally underestimated.
• Important: Flow also depends on the size of the area of interest. Be careful when comparing different measurements or subjects. Make sure that the Flow areas only cover the section of the blood vessel or gut, and not other body parts.

Main Steps

1. Draw the flow areas.
2. Acquire flow data.

Draw the Flow Areas

To Load Video Files

1. Click the Add Video(s) button.
2. Select one or more video files, and click Open. To select multiple files, hold the Ctrl key down and click each file name.
3. The list of loaded video files appears. The video window shows the first video in the list.

Tip: To select another video for preview, select the check box near its name.

To Draw the Flow Areas

1. Select one of the video files in the list.
2. Click one of the drawing tools and draw a shape over the area of interest of a subject. Make sure that the shape includes the entire section of the blood vessel or gut, not other areas. If the shape includes areas in which there is no flow, Flow statistics will be underestimated. For details about drawing shapes, see Add a Measurement.
3. Select an existing subject to assign the shape to it, or select Add Subjects.
4. For multiple subjects: if you selected Draw template shapes for all subjects, all shapes are copied at the top of the video window. Move each shape to the corresponding vessel or gut section.
5. Click a shape and drag the handles to resize and adapt it to the vessel or gut section. Play the video for a clear view of the flow in those regions.

Tip: To better compare flow measurements between subjects, draw Flow shapes of equal size and shape. For this purpose, use the Duplicate function. Right-click a shape and select Duplicate. In the context menu that appears, select an existing subject to assign the shape to it, or select Add Subject.

6. Repeat the entire procedure for each video file to analyze.

Tip: The Status column tells you which step is next for each video file.

Next Steps

• The video is analyzed up to its end. If a subject changes position significantly throughout the video, you must specify the stop time for the measurement (see To Set a Stop Time for a Measurement). Optionally, specify the new location as a new measurement (see To Add a New Measurement for the Same Subject).
• Acquire flow data.

Acquire Flow Data

To Acquire Flow Data

1. Make sure that all flow areas in your videos are marked, and in the correct video fragments.
2. To acquire data for the current video, click the Acquire button. To acquire data for all videos where subjects have been defined, click Acquire All.
3. At the end of acquisition the Status column in the video list says Acquired.

Notes

• If you resize a shape after acquisition, the flow statistics for that measurement are cleared and the Status column says Next: Acquire. Click Acquire to acquire the data.

Flow Statistics

In the list below the video window you find the flow statistics per subject and measurement: Flow Activity (%).

Notes

• The video frame corresponding to the Stop time is not analyzed. Video is analyzed from Start to Stop (included).

See Also

• Trial Statistics
• Group Statistics and Charts
• Export Statistics
• Export Raw Data

Source: DanioScope 1.1 Reference Manual - Flow, Noldus Information Technology