Sunday, 13 May 2018

Imaging the Rim




A chronic Active Lesion has a demyelinated centre and rim of myelin damage/removal by macrophages. These can be seen on a 7T magnetic resonance imaging scanner, but this study shows they can also be seen on a lower power 3T machine. If you can see it then you can monitor it.

Absinta M, Sati P, Fechner A, Schindler MK, Nair G, Reich DS. 
Identification of Chronic Active Multiple Sclerosis Lesions on 3T MRI. AJNR Am J Neuroradiol. 2018. doi: 10.3174/ajnr.A5660. [Epub ahead of print]

BACKGROUND AND PURPOSE: MR imaging-pathologic studies have reported that paramagnetic rims on 7T susceptibility-based MR imaging identify, in vivo, the subset of MS lesions with compartmentalized inflammation at the lesion edge and associated remyelination failure. Here, we assessed the reliability of detecting these rims on high-resolution 3T phase images.
MATERIALS AND METHODS: High-resolution T2* and phase MR imaging was collected in 20 patients with MS at 3T (3D segmented EPI, 0.65 mm3) and 7T (2D gradient-echo, 0.2 × 0.2 × 1 mm) MR imaging. In each case, 5 discrete chronic (non-enhancing) MS lesions were selected on T2 FLAIR images for rim evaluation. Five raters experienced in MS imaging contributed to the rim assessment, of whom 3 worked independently on 3T data, and 2, on 7T data. Consensus agreement was reached for both 3T and 7T rim evaluations. Discrepancies between 3T and 7T were discussed, and consensus was reached.
RESULTS: Phase rims were seen in 34 lesions at 7T and in 36 lesions at 3T by consensus. Inter- and intrarater reliability were "substantial/good" both at 3T and 7T analysis (Cohen κ, >0.71). Based on consensus agreement, the reliability of rim visualization at 3T versus 7T was 0.78 (κ) with a pair-wise agreement of 90%. More lesions were judged to be false-positive or false-negative at 3T than at 7T.
CONCLUSIONS: Nearly all 7T paramagnetic rims can also be seen at 3T. Imaging at 3T opens the possibility of implementing paramagnetic rims as an outcome measure in multicenter, MR imaging-based clinical trials aimed at treating perilesional persistent inflammation and its potential effects on remyelination.


http://www.ajnr.org/content/ajnr/early/2018/05/03/ajnr.A5660/F2.large.jpg?width=800&height=600&carousel=1

10 comments:

  1. In the classic discussion whether "MS is a single disease, or are 3" 7T resolution images from magnetic resonance imaging will make all the difference. If really in the PPMS there is active inflammation, will IMT of 7T show this ongoing inflammation, or not?!

    And it may still show whether brain demyelinating lesions are actually different from spinal cord lesions?!


    http://multiple-sclerosis-research.blogspot.com/2016/08/distinct-types-of-immune-cell-associate.html?m=1

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  2. According to you, a chronic active lesion is a place were immune cells sensitized against myelin repeatedly pass the BBB of a vein and spread rather uniformly around it. Since there are many other parts of the brain were lesions do not form, what is it so special about the lesions sites from a cellular point of view? And more so, what is it so much more special about chronic lesion sites?

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    1. Plasma cells, microglia and astrocytes. Paper upcoming.

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    2. A future reference is hardly an answer, but let's pretend it is. Does your paper hold an explanation of Dawson fingers? If not, then it's far off the target.

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    3. That's why I didn't put you down as a referee, VV ;-)
      Dawson's fingers were discussed here back in 2011.
      http://multiple-sclerosis-research.blogspot.com/2011/10/ms-pathology-dawsons-fingers.html
      A link with lesions and CSF anomalies ie oligoclonal bands are one of the subjects of the upcoming paper.

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    4. Yes, they were discussed. I remember professor GG completely misunderstanding what it means for a lesion to be venous in origin. He was talking about venous stasis, whereas i was talking about rapid, instant, venous blood backjets. He also raised a question against a possible role of CSF in the formation of Dawson fingers. Apparently, he changed his mind.

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    5. Ah yes, I was wondering how long it would be before the thorny issue of blood flow reared its head. Just off to the bookies to collect my winnings ;-)

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    6. In case you missed it.
      https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5833494/
      "Venous PTA cannot be recommended for patients with relapsing-remitting multiple sclerosis."

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  3. Rest assured that this is always behind anything i say. Still, the study did not disprove the venous origin of MS. It said that PTA, as performed today, is not a suitable method to deal with the big range of venous anomalies found in people with MS.

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    Replies
    1. In a way I admire your dogged persistence. Just go with the flow VV ;-)

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