Empowering vision:DSA

Digital Subtraction Angiography (DSA) is an advanced radiographic technique for selective visualisation of the vascular system. In this process, a reference X-ray (mask) image is electronically subtracted from a sequence of images acquired after a radiopaque contrast agent is injected. With this technique, static anatomical structures (e.g. bone tissue) are deleted, highlighting only the blood vessels.

The feature that makes our DSA particularly effective is called:

Auto Shifting Pixel
It automatically aligns the mask image and images captured after the contrast agent is injected (contrast images), compensating for any patient movements. The user can define the ROI where the Auto Shifting Pixel is applied, improving alignment in the areas of interest. Manual intervention on specific frames is always possible to optimise the performance.

With our library, the following can also be generated:

Sum Image

The Sum Image is a diagnostic representation that combines multiple frames acquired while the contrast agent is passing through the blood vessels. The pixel-by-pixel sum of images already processed with subtraction yields a single synthetic image optimized to highlight details of the vascular anatomy, thereby providing a complete overview that is particularly useful for reporting.

Landmark

The Landmark feature is an image processing operation used in diagnostics to improve the visualization of vessels while maintaining an idea of the surrounding anatomy. The Landmark image consists of the contrast image, from which the mask is subtracted with a variable degree of transparency. The result is an image in which anatomical structures are visible, providing context with respect to the highlighted vessels.

MaxOp & RoadMap

The MaxOp functionality is used in the operating environment to highlight the densest structures (typically vessels filled with a contrast agent), improving their visibility on a single image (PeakMap).

The RoadMap function is aimed at guiding catheter insertion in real time. In this technique, the PeakMap image is subtracted from the real-time fluoroscopy flow, highlighting the vascular system without needing to continuously inject the contrast agent.

DSA offers two operating modes:

• Real-time: performing the digital subtraction during the exposure
• Post-acquisition: activating the Auto Shifting Pixel feature and performing the digital subtraction after the acquisition

Strengths:

• Automatic compensation of patient movements
• Dedicated features for diagnostics (Auto Shifting Pixel, Sum Image, Landmark) and operations (MaxOp, RoadMap)
• Compatible with any detector that meets the diagnostic standards required by the acquisition system

In the standard workflow, a plain X-ray (without contrast agent) is taken as a reference image, and the contrast agent is then administered.

In Real-time mode, the procedure continues with image subtraction, yielding an image that highlights the vascular system.

In Post-acquisition mode, however, the Auto Shifting Pixel is applied before image subtraction. This produces a final output similar to the previous one, but with better alignment in the anatomical area of interest, resulting in higher image quality.