Forgot your password?
typodupeerror
Medicine Science Technology

Detecting Chemicals Through Bone 23

Posted by Unknown Lamer
from the full-of-poison dept.
MTorrice writes "To understand the brain and its chemical complexities, researchers would like to peer inside the skull and measure neurotransmitters levels as the brain at work. Unfortunately, research methods to measure levels of chemicals in the brain require drilling holes in the skull, and noninvasive imaging techniques, such as MRI, can't detect specific molecules. Now, as a first step toward a new imaging tool, chemists report they can detect molecules hidden behind 3- to 8-mm-thick bone."
This discussion has been archived. No new comments can be posted.

Detecting Chemicals Through Bone

Comments Filter:
  • by Travis Mansbridge (830557) on Saturday November 23, 2013 @11:18AM (#45500773)
    Trepanning always gets a bad rap.
    • Trepanning always gets a bad rap.

      Bad rap? You're trying to imply that there's such a thing as good rap?

  • Question (Score:4, Interesting)

    by excelsior_gr (969383) on Saturday November 23, 2013 @11:22AM (#45500789)

    Isn't MRI practically NMR? NMR is used for chemical analysis. Then how come MRI machines can't be programmed to do the same?

    • by localroger (258128) on Saturday November 23, 2013 @11:37AM (#45500849) Homepage
      NMR only reports the presence of (certain isotopes of) nuclei. With most biochemicals of interest being made almost entirely of the same four atoms (carbon, hydrogen, oxygen, and nitrogen) there's nothing to tell the MRI which particular large molecule the atoms are part of.
      • Re: (Score:3, Informative)

        by Anonymous Coward

        NMR only reports the presence of (certain isotopes of) nuclei. With most biochemicals of interest being made almost entirely of the same four atoms (carbon, hydrogen, oxygen, and nitrogen) there's nothing to tell the MRI which particular large molecule the atoms are part of.

        Are you sure you know what you're talking about?

        NMR spectroscopy perhaps the most powerful analytic technique in modern organic chemistry -- it works on molecules as simple as hydrocarbons and as complex as proteins. Information is extra

      • by venicebeach (702856) on Saturday November 23, 2013 @12:00PM (#45500927) Homepage Journal
        The summary is overly dismissive of existing techniques.

        In addition to MR spectroscopy, [wikipedia.org] chemical activity in the brain can be measured with techniques like PET [wikipedia.org] and SPECT [wikipedia.org].

        All of these techniques have their advantages and disadvantages, and its certainly always great to have new options.
        • When I first read TFS I thought the researchers had come up with a new way to look at in vivo molecules without 'tags' - molecules introduced into the organism to trigger whatever probe technology you were using. If I'm reading the article correctly, this doesn't seem to be the case - you do have to introduce some tag, presumably into the brain for neuro imaging. Thus, it doesn't have the utility of say an NMR that can read the sample directly (albeit in a tiny glass tube).

          It is more like PET / SPECT and

    • Isn't MRI practically NMR? NMR is used for chemical analysis. Then how come MRI machines can't be programmed to do the same?

      I think they have/are been: http://www.ncbi.nlm.nih.gov/pubmed/9339439 [nih.gov] http://www.ncbi.nlm.nih.gov/pubmed/23494381 [nih.gov] http://www.ncbi.nlm.nih.gov/pubmed/12891651 [nih.gov] http://web.mit.edu/newsoffice/2010/brain-imaging-0301.html [mit.edu]

    • by femtobyte (710429)

      NMR for chemical structure and MRI for imaging both rely on the same physics principles (signals emitted by polarized nuclei precessing in a magnetic field). However, there will be significant differences in the hardware optimized for each task (not a software matter of "reprogramming the machine"). Imaging (MRI) hardware is primarily interested in answering the question "where are the nuclei located?", while chemical NMR is about getting an extremely precise measurement of "how fast are the nuclei precessi

      • Of course, as NMR/MRI technology improves, people are able to get more and more precise chemical composition information at the same time as measuring the position/density of nuclei.

        You'd need tremendous weak signal detection capabilities for that. I believe this is a case of "either X or Y" situation, or perhaps the best we can hope for is meeting somewhere in the middle: by integrating a signal from larger areas, you regain some measure of "chemical" resolution at the cost of some spatial resolution. (A bit like the color graphics mode on ZX Spectrum. :-))

        • by femtobyte (710429)

          Yes, it's a difficult tradeoff, and what you can tell with position information is nothing close to what you can get from a dedicated high resolution instrument (with a tiny sample volume). Note this highly informative post [slashdot.org] further down the thread by a working MRI physicist, indicating some level currently obtainable, from which one might expect gradual improvements with fancier instrumentation (squids! squids everywhere!).

    • Isn't MRI practically NMR? NMR is used for chemical analysis. Then how come MRI machines can't be programmed to do the same?

      Perhaps it's a difference in wiring rather than a difference in programming. NMR chemical analysis gives you high resonance frequency resolution but couldn't care less about spatial resolution. MRI attempts to project the whole 4D thing into high contrast, high spatial resolution imagery instead, while the molecular recognition abilities are sacrificed. (Chemical analysis via NMR integrates the signal for sparsely concentrated molecules over a large area, how would you reconcile that with high spatial resol

  • The reported method requires that specially coated nanoparticles are first injected though the bone. That is just drilling a smaller hole.

  • by DrLudicrous (607375) on Saturday November 23, 2013 @01:18PM (#45501307) Homepage
    Disclaimer: I am a physicist who works in MRI. MRI can be used to measure concentrations of certain biochemicals. MRI is sensitive enough to different proton-containing species that the frequency difference between fat and water causes image artifacts that can pose great difficulty. Not all biomolecules are sufficiently concentrated in the brain, or have a spectrum that is unique enough to be measured in vivo. A good example of a brain chemical that can be measured is N-acetyl aspartate (NAA), which has a proton peak at around 2 ppm that doesn't overlap with much else. Magnetic resonance spectroscopy is very difficult, and is most easily accomplished on research scanners operating at 3 tesla or higher. The reason for this is that rather than letting all hydrogen nuclei contribute to one signal that is then spatially located, one must parse what kinds of nuclei (i.e. what their chemical shift is) within each voxel. This not only imposes technical difficulties, but reduces the signal to noise ratio, potentially requiring more signal averaging in order to see sufficient signal above the noise floor.
  • by Qwerpafw (315600) on Saturday November 23, 2013 @02:13PM (#45501705) Homepage

    The article summary is incorrect. MR Spectroscopy (MRS) is used today to measure molecules inside the brain. Resolution is not great for 3D MRS in clinical applications (due to the tradeoff between SNR and resolution, acquisition times are slow), but it's more than high enough to distinguish between different regions of the brain. And it's very common to perform single-voxel imaging and only get the spectroscopy for a given piece of tissue - for example, where a tumor is located.

    MRS easily detects metabolites and ratios, like choline, NAA, as well as things like lipids, and alcohols. It requires expensive scanners, but it works and is used routinely in brain imaging today. The article mentions something that does not work clinically, and is being demonstrated in a lab with a piece of meat. The technology in the article is not a "first step" to understanding molecules in the brain, because we already have that technology today with MRS.

Put no trust in cryptic comments.

Working...