In a nutshell, in progressive MS, there appears to be ongoing changes in gray matter damage that is unrelated to white matter damage or to brain atrophy. That also supports the theory that axonal damage is the prevailing problem behind progressive MS (with OR without accompanying demyelination).
Neuroimage. 2005 Feb 15;24(4):1139-46. Epub 2004 Nov 26. Related Articles, Links
Short-term accrual of gray matter pathology in patients with progressive multiple sclerosis: an in vivo study using diffusion tensor MRI.
Rovaris M, Gallo A, Valsasina P, Benedetti B, Caputo D, Ghezzi A, Montanari E, Sormani MP, Bertolotto A, Mancardi G, Bergamaschi R, Martinelli V, Comi G, Filippi M.
Neuroimaging Research Unit, Scientific Institute and University Ospedale San Raffaele, Milan, Italy; Department of Neurology, Scientific Institute and University Ospedale San Raffaele, Milan, Italy.
The mechanisms underlying the progressive course of multiple sclerosis (MS) are not fully understood yet. Since diffusion tensor (DT) MRI can provide quantitative estimates of both MRI-visible and MRI-occult brain damage related to MS, the present study investigated the value of DT MRI-derived measures for the assessment of the short-term accumulation of white and gray matter (GM) pathology in patients with primary progressive (PP) and secondary progressive (SP) MS. Fifty-four patients with PPMS and 22 with SPMS were studied at baseline and after a mean follow-up of 15 months. Dual-echo, T1-weighted, and DT MRI scans of the brain were acquired on both occasions. Total lesion volumes (TLV) and percentage brain volume changes (PBVC) were computed. Mean diffusivity (MD) and fractional anisotropy (FA) maps of the normal-appearing white (NAWM) and gray matter (NAGM) were produced, and histogram analysis was performed. In both patient groups, a significant increase of average lesion MD (P = 0.01) and of average NAGM MD (P = 0.007) was found at follow-up. No significant differences between PPMS and SPMS patient groups were found for the on-study changes of any MRI-derived measure. No significant correlations were found between the percentage changes of DT MRI-derived measures and those of TLV and PBVC. No significant changes of DT MRI-derived measures were observed in age-matched healthy controls over the same study period. Over a 1-year period of follow-up, DT MRI can detect tissue changes beyond the resolution of conventional MRI in the NAGM of patients with progressive MS. The accumulation of DT MRI-detectable gray matter damage does not seem to merely depend upon the concomitant increase of T2-visible lesion load and the reduction of brain volume. These observations suggest that progressive NAGM damage might yet be an additional factor leading to the accumulation of disability in progressive MS.
PMID: 15670691 [PubMed - in process]
NIH Licenses New MRI Technology
NIH Licenses New MRI Technology
That Produces Detailed Images Of Nerves, Other Soft Tissues
National Institute of Child Health and Human Development
NIH NEWS RELEASE
FOR IMMEDIATE RELEASE
Monday, July 29, 2002
Robert Bock or
NIH Licenses New MRI Technology That Produces Detailed Images of Nerves, Other Soft Tissues
A new technology that allows physicians and researchers to make detailed, three-dimensional maps of nerve pathways in the brain, heart muscle fibers, and other soft tissues has been licensed by the National Institutes of Health (NIH).
The new imaging technology, called Diffusion Tensor Magnetic Resonance Imaging (DT-MRI) was invented by researchers now at the National Institute of Child Health and Human Development (NICHD). DT-MRI may allow physicians and researchers to better understand and diagnose a wide range of medical conditions such as stroke, amyotrophic lateral sclerosis (Lou Gehrig's disease), multiple sclerosis (MS), autism, attention deficit disorder (ADD), and schizophrenia. NIH has signed an agreement with GE Medical Systems, licensing them to produce and market the product.
"NIH's mission is to support research that improves the health of the public," said Duane Alexander, M.D., Director of NICHD. "The recent licensing of DT-MRI ensures that the technology produced as a result of NIH research is further developed and marketed to medical institutions where patients can benefit from its use."
Like conventional MRI, DT-MRI is a technology that produces high quality 3-D images of the inside of the body, painlessly, non-invasively, and without using contrast agents or dyes. In addition, DT-MRI produces sophisticated images of soft tissues by measuring the three-dimensional random motion of water molecules (diffusion) within the tissues.
Although water may appear placid in a jar or cup, individual water molecules are constantly in motion, colliding with each other at extremely high speeds. These high-speed collisions cause the water molecules to spread out, or diffuse, similar to the way a drop of dye placed in a jar of water spreads in a spherical pattern. In some tissues, such as gray matter in the brain, water also diffuses in an approximately spherical pattern. In contrast, in tissues containing a large number of parallel fibers, such as skeletal muscle, cardiac muscle, and brain white matter, water diffuses fastest along the direction in which the fibers are pointing, and slowest at right angles to it. DT-MRI uses this information to produce intricate three-dimensional images of the tissue's architectural organization and local structure.
Changes in tissue properties that can be measured with DT-MRI can often be correlated with processes that occur in development, degeneration, disease and aging. As a result, doctors and scientists can use DT-MRI to diagnose and assess a growing number of diseases and better understand how tissues in the body function.
Since its invention, DT-MRI has had a wide range of applications. Scientists and clinicians have used it to map nerve pathways in the brain, diagnose acute stroke, and determine the effectiveness of new stroke prevention medications. DT-MRI has also been used to map subtle changes in white matter in diseases such as Lou Gehrig's Disease, adrenoleukodystrophy (ALD), MS, and epilepsy. This information has helped scientists and clinicians better understand the development of these disorders, an important first step in eventually devising new methods to treat them.
Others are using DT-MRI to assess the type and severity of brain tumors and to plan the surgical procedure to remove them. For example, brain surgeons planning tumor removal surgeries are beginning to use DT-MRI images to help them better distinguish between healthy brain tissue and tumors. Other researchers are investigating DT-MRI's use in diagnosing and determining the stage of certain cancers, such as prostate cancer.
DT-MRI has also been used to study cognitive and behavioral disorders, such as schizophrenia, ADD, and dyslexia. Presently, scientists are using the new technology to associate these conditions with specific anomalies in brain anatomy.
"If we could establish a strong connection between an anatomical deficit and a particular disorder, it might be possible to one day use DT-MRI as a screening tool," said Peter Basser, Ph.D., principal inventor of DT-MRI and Chief of the NICHD Section on Tissue Biophysics and Biomimetics.
Pediatric researchers are using DT-MRI to learn more about normal brain development in infants and children. Other researchers are investigating DT-MRI's use in assessing head trauma and cardiac abnormalities.
"Licensing technology like DT-MRI benefits the NIH, the private sector, and the public at large," said Krishna Balakrishnan, Ph.D., MBA, Marketing Group Leader of NIH's Office of Technology Transfer, "It motivates the business world to further develop the product invented at NIH and get it to the public. It also benefits further NIH research by validating its societal applications."
In addition to Peter Basser, Dennis LeBihan and James Mattiello also contributed to the development of this invention.
The NICHD is part of the National Institutes of Health, the biomedical research arm of the federal government. The Institute sponsors research on development, before and after birth; maternal, child, and family health; reproductive biology and population issues; and medical rehabilitation. NICHD publications, as well as information about the Institute, are available from the NICHD Web site, http://www.nichd.nih.gov or from the NICHD Clearinghouse, 1-800-370-2943; e-mail NICHDClearinghouse@mail.nih.gov