Pixel operations

Probe, arrow annotation and Cobb angle tools

Read a pixel value, point at a finding with a labelled arrow, or measure a Cobb angle.

Three tools on the top bar, next to the length and angle measurements, for checking a value or marking a finding without leaving the viewer.

Steps

Open an image or series (⌘O) in the 2D view.
Probe: select the tool and click a point. The text next to the point shows the pixel index and the pixel value, with its unit when the image has one (HU on CT). See Probe.
Arrow: select the tool and press on the point you want to mark and drag towards where the label should sit; the arrow head is drawn where the drag starts. Type the label in the dialog and select Add arrow. Cancel discards the arrow. Double-click an arrow to change its label. See Arrow annotation.
Cobb angle: select the tool, drag the first line, then drag the second. The angle between them appears in degrees. See Cobb angle.

The annotations are never written into a DICOM file’s pixel data. Export Viewport State (GSPS) saves them as graphics and text in a separate presentation state; see Export viewport state. Export Image and Export Video draw them onto the picture or clip when Include annotations is ticked.
The tools are not available in the volume render, which has no slice to place them on.
The probe does not report SUV on PET images.

Pixel readings, labelled arrows and Cobb angles drawn over the image, with the source pixel data unchanged.