Hello,
From what I've understood, MRI works for imaging tissues mostly consisting from hydrogen. Since imaging of amyloid beta peptides is also available, I wanted to know what chemical element do Aβ mostly consists of? I wasn't able to find it online. I only found that for Aβ imaging, NMR was used, but from what I've understood it is used for analyzing many isotopes of different chemical elements, so it's not that informative. I would be very grateful if anyone could refer me to some reading material or refer me to a place where I can find this information.
Thank you very much for your time an attention.
The molecular formula is C_119H_194N_28O_33S from which I deduce it mostly consists of hydrogen and carbon
First of all, you seem to think that NMR and MRI are separate modalities, but actually MRI is a sub-discipline of NMR.
Yes, Beta Amyloid is a hydrocarbon just as all other macromolecules in the body. MRI of living tissues usually only sees the free water in the tissue, and depending on parameters, maybe the fat. The hydrogen atoms in macromolecules have shorter relaxation times and much lower concentrations that water, so they don't show up in typical MRI images. There are ways around these limitations, but distinguishing one macromolecule from another in the body, in an MRI experiment, is nearly impossible.
My understanding is that Beta Amyloid plaques can be seen in gradient-echo MRI images, because the plaques contain a build-up of iron, which leads to a very short T2* relaxation time, in the nearby water as well. Therefore the plaques appear as signal voids in the images.
below is the link that could be of some help to you. https://www.nature.com/articles/aps201728
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