What is the initial step in digital subtraction angiography?

The initial step in digital subtraction angiography (DSA) involves acquiring the mask image. This mask image serves as a baseline representation of the vascular structures without the contrast agent, allowing for the extraction of the detailed images that follow. By capturing this initial image, healthcare practitioners can later subtract it from subsequent images taken after the contrast material is injected.

This subtraction is critical because it enhances the visibility of the vessels filled with contrast while removing the background structures, ultimately highlighting the details of the vascular anatomy. The effectiveness of this process relies on having a clean, accurate mask image to provide a clear contrast for analysis.

The other choices represent subsequent steps that are dependent on first obtaining that essential mask image. Acquiring the final image, injecting contrast material, and processing the image all occur after the mask image is captured, underscoring the foundational importance of this initial step in the DSA procedure.