DSA (Digital Subtraction Angiography) subtracts a reference mask from a contrast-enhanced XA image to isolate vessels. Segmentation tools (Bounding Box, Smart Paint) help you outline regions of interest for volume measurement or export.
Step 1: Apply a DSA mask
Open an XA series. Click Digital Subtraction in the toolbar. The viewer picks a mask frame automatically. To change the mask, right-click and select Set mask frame, then choose a pre-contrast frame.
Step 2: Adjust mask blending
Use the opacity slider to blend mask and live image. Enable Pixel Shift to correct for patient motion between mask and live frames.
Step 3: Bounding Box segmentation
Click Bounding Box in the Measurements toolbar. Click and drag to enclose a structure (for example, a lung nodule). The viewer auto-segments within the box.
Step 4: Smart Paint
Click Smart Paint and paint over the structure of interest. The tool grows the segment along intensity gradients, giving cleaner boundaries than freehand. Toggle to eraser mode to refine.
Step 5: Save or export the segment
Segments save as DICOM SEG objects and appear with a SEG badge on the thumbnail. Export via the Export dialog if you need to send the segmentation to an external planning tool.
Tips
- DSA quality is limited by motion between mask and live frames. Pixel Shift helps but cannot recover severely mis-registered acquisitions.
- Smart Paint is tuned for high-contrast boundaries (bone-soft tissue, lung-soft tissue). On low-contrast MR, freehand Pencil may be faster.
Related articles
- 3D volume rendering, MIP and MinIP
- Basic measurements: length, angle, ROI, area and volume
- Exporting studies