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Labels

MD.ai Annotator has a flexible labeling system that helps you annotate for all kinds of medical AI projects, including for classification, localization, segmentation, and regression models.

Annotator supports both Global and Local labels. Labels can be moved, edited, and deleted after creation.

Global Labels

A global label is applied to the whole image (eg, Normal) which is useful for letting your training algorithm know that this particular image should be in a particular category. It can also be used to label a series or entire exam.

Create a global label:

A global label can be applied at the exam, series, or image level.

You can also use a global label as metadata, for example Ignore for images of insufficient quality or perhaps an image that doesn't belong in the dataset.

Local Labels

A local label can be applied to a specific region on an image (eg, Lung Nodule). For a particular local label, multiple instances of that label can be applied to different regions on the same image (eg, for multiple lung nodules).

Create a local label:

When creating a local label, select one of the annotation modes which will be used throughout the project for that particular label.

Metadata Labels (New)

Metadata labels can be used for information that you need to display across all label groups, eg history. Use the API to import information into the notes portion of this label. The information can then be viewed on hovering over the label. Metadata labels can be at the image, series, or exam level.

Sublabels

An arbitrary number of sublabel layers can be created to streamline label appearance and annotation. Any type of annotation can be chosen for the main header label and sublabel. You can also mix and match modes and types of annotations.

Note - it's important to plan out the structure of your labels and sublabels before you start creating them. If you're not sure, create extra sublabels and you can delete them later by turning on Show All Sublabels.

Create a sublabel:

Reorder Labels

From Label Controls select Reorder Labels and drag and drop items in Labels Column in desired order. Click Label Controls again to set.

Annotation modes

  • Bounding Box which also calculates a width and height

  • Freeform annotation. Edit by mouse hovering over the edge and dragging and/or sliding any of the dots that appear. You can add control points to the figure for fine tuning. Freeform mode also calculates the longest diameter (even if that line is not fully contained within the freeform shape).

  • Polygon annotation mode calculates the longest diameter. Edit the polygon shape by hovering over the edge and dragging one of the polygon corners.

  • Simple Location coordinates are applied in this mode

Cloning a Label Group

Open the settings icon next to Label Group, enter name for the new clones group, and hit Clone button. All the labels from the first group will be duplicated and entered into the cloned group.

Preventing Additional Labels

Open the settings icon next to Label Group, chose the checkbox No Adding New Labels to prevent administrators from creating new labels for the group. Chose the checkbox No Applying Labels to prevent users from applying further labels to the group.

This allows you to freeze the label group.

Radlex Tags

Radlex coding tags can be added to global and local labels in order to use standardized terms for labels. They can also be added to notes.

Label Thumbs Up or Thumbs Down

Clicking on the Thumbs Up icon on the label tag will add a Positive Review to the label. Conversely, clicking on the Thumbs Down icon will add a Negative Review

Label Controls

Filter

All users can Filter and Hide labels as well as bulk remove their own annotations. Administrators can edit, reorder, and delete labels.

Choose the filter option in the Labels Controls and select the labels and label group you would like to filter by. Then click filter again. When you open the Exam window in the Navigation column, you'll see only the filtered cases.

Types of filters

  • AND filter will show only the exams that contain all the labels you have selected.
  • OR filter will show the exams that contain any of the labels you have selected.
  • NOT filter will show only the exams that do not contain the labels you have selected.

Hide labels

Hide works similarly. Choose the hide option in Label Controls and select the labels you would like to hide. You can also hide individual annotations on an image by using the hide icon on the annotation tag.

Reorder labels

Drag labels into the position to change their order.

Remove labels in bulk

BULK REMOVE is a feature to remove specific label annotations from the exam, series, or image level. An administrator can remove all annotations from an image, series, or study from any user. This is useful to remove unwanted annotations added with the interpolator tool.

bulk-removal.gif

Edit labels

Change the label title, color, and Radlex tags using this option.

Delete labels

This allows you to delete a label and with it, all the associated annotations from the entire project.