First you may be asking yourself what does it mean to clip or prune an EEG study? Why is it beneficial?
Clipping an EEG (electroencephalogram) study involves removing sections of the recording that are not of interest or that may contain artifacts, noise, or irrelevant data.
Clipping helps by focusing only on the relevant segments of the EEG, researchers and clinicians can more easily analyze the data without being distracted or misled by irrelevant information.
EEG recordings often contain artifacts (e.g., from muscle movements, eye blinks, or electrical interference) that can obscure the true neural signals. Clipping allows these artifacts to be excluded from the analysis.
Pruning the data reduces the amount of information that needs to be stored and processed, making the analysis more efficient and less computationally intensive.
For clinical purposes, focusing on specific events (such as epileptic seizures) can aid in more accurate diagnosis and treatment planning.
Pruned studies can be more easily shared, reviewed, and reported, as they contain only the most relevant data.
What are the differences in to manually clip and prune a review study versus using automated clip marking?
To manually clip a study you will need to utilize the Mark Clip Start and Mark Clip End buttons to complete all clips following your facility's clipping protocol.
In addition to or instead of marking clips manually, you can use the automated clip marking feature where the system automatically clips selected events throughout the study. Even running auto-clips you may still need to manually mark certain additional clips such as state changes/transitions, sleep cycles, significant artifacts, etc. Follow criteria set by your facility.
For example, you can choose to automatically select all events marked by a reviewing technician. Another option could be to have the software automatically mark a clip at specified regular intervals throughout the study (auto-sampling).
Tips and Tricks of running the Automatic Clipping:
Set auto-clipping rules:
Click Edit > Clips > Auto Clips to display the Automatic Clipping dialog box.
There will be preset Automatic Clipping Rules including Auto-Sample, Patient Event, XLEvent and XLSpike. You may need to change or unselect these rules settings.
Click Auto-Sample if you want the system to make a clip at specified intervals. For example you may want to clip 10 minutes every 60 minutes.
Click Patient Events, XLEvent and/or XLSpikes to specify which event types to clip. For Patient events you may want to adjust the time before and after the event, It is likely best to unselect the XLEvent or XLSpike options as frequent XLEvents and XLSpikes may be marked whether they cerebral or artifactual. Unselecting can assist in focusing only on the relevant segments of EEG, to unselect a rule click in the box with the check mark. You know the rule is unselected when the box is empty.
You can create your own custom rules for the auto-clipping function. This can be useful if, for example, you need to mark your own notes with your initials and could add a custom rule that would find all of your notes and clip them.
There is no limit on how many custom rules can be created. The rules are stored locally and are available to all the users on a given station. Each rule is configurable and marks notes based on the criteria explained in the table below. All the set-up criteria has to match in order for the note to be included in a clip.
Click Add Rule. The Add Rule dialog appears.
Complete the information requested in the Add Rule dialog and click OK.
Rule name- Use to name your rule.
Note type- This type is always assigned by the software. If you select one of the fixed supported types, You can also leave as Not selected.
Note subtype- The list of available subtypes is dependent on the note type. Some note types do not have subtypes. For example Note type Information Notes has several subtypes such as Comments, Impedance Check and more.
Note text- This setting allows you to filter notes based on their caption. For example, in the picture above, a rule is set up to find all information comment notes (notes usually entered by typing on the keyboard) and selecting only the notes that contain the sz sub-string. For this rule, notes marked as szED, sZ1, etc., will be marked and included in the pruned study. Other info comments will be not. The "Note text" must be unique to the rule and you must spell the notes correctly.
Note Comment- This is an advanced setting that can be used to filter notes based on the comment field. You can leave this section blank.
Match case- If this setting is selected (checked), text search will be case sensitive. You can leave unselected.
Match whole word only- If this setting is selected (checked), the pattern will be compared with the whole words. This means, for example, that if limb is set as a pattern, it will match only if the note text contains the word limb. It will not pick up limbo or climb. You can leave this unselected.
Note duration- This setting allows for the finding of notes that are at least, or at most, a specified number of seconds in duration. This option is useful for notes that have duration. After adding all custom rules make sure that is correctly set on the automatic clipping rules page to set how far you want clip to be before and after clipped note. You may leave the duration blank.
After adding custom rules review that you have all rules selected and edited to match your criteria.
If you do not want to use a clipping rule unselect it.
Setting times before and after clip are especially helpful. For example 60 second before and after a Physician Note or Skin Check may be relevant information to the reading doctor.
Try to have you Default clip name and hot keys match completely. If rules and hot keys do not match these clips may not be selected.
Select the Include video box if you want the video to be included in the clip and when study is pruned.
Use "hot keys" when reviewing:
What are "hot keys"? Hot keys are an unofficial term used to describe the buttons that appear on the Note toolbar. Different buttons appear on the Note toolbar depending on whether you are recording a live study (acquisition mode) or reviewing a previously recorded study (review mode). To open the Note toolbar, choose View > Toolbars > Note. When using the auto clip feature you will be using the Note Toolbar in Review Mode.
Click a Note button to instantly insert a note at the current location of cursor. During reviews you can add hot key notes such as Skin Check, Physician Note, and more so they will be clipped when you run the auto clips.
The Notes menu lists preset notes that can be manually added to your study by qualified practitioners. Selecting an item from the menu adds the note. The items on the Notes menu vary depending on whether you are in Acquisition or Review mode.
While reviewing if criteria does not fall into auto clip rules manually clipping certain additional clips such as state changes/transitions, sleep cycles, significant artifacts, etc. Follow criteria set by your facility.
Running Auto-Clips:
If all your auto clip rules are set, you have added any hot key notes, and completed any necessary manual clips then you are ready to run the auto clips.
If this is the first-time using auto clips on you profile follow these steps:
Click on the Edit Clips button on the toolbar
The Clips box will appear. Select the button that says Auto Clips.
Be sure that your autoclips are set up as correctly. If you have multiple servers you may need to set up the auto-clips multiple times.
Click the Mark Clips button. If there are any existing auto-clips, the system will delete them before creating new auto-clips based on the current rules (it does not delete clips that were created manually by users). The Clips box appears with all the clips.
Proceed to the instructions in Processing Clips in the Clips Box. This may mean closing Clips Box. If the study is not complete you may need to run the auto clips again later. You may also review all clips to see if anything is missed.
Once you have selected clips from a study, you must process them to create a new pruned study record. If creating a pruned study make sure you are following your facility protocol.
A second study appears in the database that contains only the data in the marked clips. The clips are all merged. To see the pruned study listed in the database, return to the Natus Database. If the study does not appear immediately, click the Refresh toolbar button.
Only Create a pruned study creates a second study in the database. Delete all video ... does not!
The pruned study is now added to the list of studies in the database and can be identified by a small scissors icon in the folder column on the left side of the database table.
Overall, clipping an EEG study helps in making the data more manageable, clearer, and more relevant to the specific goals of the research or clinical assessment.
Sources:
NeuroWorks 10 - Reference Manual pages 65-72