Measurements and annotations

Prism’s measurement tools sit in the toolbar as quick tools and a fuller overflow set. Names may say primary and more depending on the build. They are Cornerstone primitives under the hood. You mostly need to know which tool matches the question in front of you.

Picking a tool

Length is basic distance on plane and has the l shortcut. Bidirectional places two perpendicular calipers for lesion long and short axes, the everyday RECIST-style check. Angle covers two-line or corner angles for vascular or orthopedic work. Cobb angle is the scoliosis pattern when the tool is available. Rectangle, circle, and elliptical ROIs give region stats such as mean and area when the panel supports them. Freehand ROI handles irregular shapes. Arrow annotate is a text pointer for screenshots and team communication, not a number. Probe reads a pixel or vector value for quick CT number checks.

Window, level, pan, and zoom are navigate tools, not stored measurements. Brush and eraser belong to segmentation, not this set.

Everyday patterns

A triage nodule often needs one length on the longest axis and a note for the report. Informal aortic angles happen after you orient in MPR. Formal hemodynamics still belong on a dedicated workstation in many services. HCC work often pairs a freehand or ellipse for rough area with bidirectional for long and short in one shot.

Groups, panels, and saves

Measurements live in groups, for example manual work versus content loaded from DICOM-SR. The panel lists type and summary stats when available. You can show or hide a group, lock a measurement, or delete when permissions allow. Some DICOM-SR items arrive protected and stay read-only. Earlier structured reports may load automatically as a reference layer.

Measurements and segmentations stay in your browser first. After a short quiet pause, Prism writes a local copy so closing the tab does not throw the work away. You do not press a special export for ordinary reading.

Horizon can also show indication-only geometry to someone following you. That is ephemeral. It does not become the follower’s saved measurements. Lite has no follow session, so those indications never leave your browser.

Status text about peers or a save still catching up is Horizon collaboration noise unless the app shows a clear error.

Annotations

Arrow annotate is for education and meeting stills where you need a pointer, not a measurement. Make sure the correct series is active before you measure. Syncing two panes does not measure in both. The active viewport still owns the tool.