• BreadOven@lemmy.worldEnglish
    33·
    4 months ago

    Having to look up MRA. It’s just MRI (NMR) but with contrast that goes specifically to the brain (maybe carb-based)?

    • Morphit @feddit.ukEnglish
      16·
      4 months ago

      Magnetic Resonance Angiogram. Yeah it’s an MRI. I guess they’re processing it somehow to enhance bloodflow like FMRI. Seems like it doesn’t require contrast.

      • SacralPlexus@lemmy.worldEnglish
        11·
        4 months ago

        Radiologist here. 👋🏻

        You are right it does not require contrast. The scan uses a special technique to reduce signal from tissue that isn’t moving so only things that are moving produce high signal and show up “bright.” Since blood is the only thing really moving in the brain - voila!

        • Morphit @feddit.ukEnglish
          3·
          4 months ago

          Neat, I was thinking it was something like motion amplification. I guess the lungs would mess with imaging of the torso, or can you pick the motion frequency to isolate bloodflow but ignore respiration?

          • SacralPlexus@lemmy.worldEnglish
            5·
            4 months ago

            The lung motion is be a problem but it is still done in some situations and the radiologist just tries their best with any motion artifacts. Since the blood vessels are so big in the chest it kind of works out, but it turns out better with contrast.

            • Morphit @feddit.ukEnglish
              3·
              4 months ago

              I see. I started reading this article which describes a whole host of different techniques. It really seems to be exploiting the physics of NMR to get this enhancement (or deficit), along with the image processing. It’s really interesting but I’d need a while to get my head around it.

    • Tar_AlcaranEnglish
      15·
      4 months ago

      Technically it’s both. It’s just that the bones stand out much more than the soft squishy insides.

    • azi@mander.xyzEnglish
      5·
      4 months ago

      There are brain x-rays called pneumoencephalographs where they replace the cerebrospinal fluid with air, x-ray, and then put the fluid back. Pneumoencephalography and angiography were really the only neuroimaging techniques available for most of the 20th century, so it was pretty common.