Nitrogen Molecule

It follows that atrophy of white or gray matter in MS likely reects axonal and neuronal loss.In a study of the spinal cord of ve MS cases, atrophy and axonal loss were studied.There was axonal loss within spinal cord lesions of between and. Atrophy was more marked in the cervical than the lumbar area and affected gray and white matter equally.Axonal loss is not the sole cause of atrophy and loss of myelin per se will contribute.Variation in glial bulk, inammation, and tissue water content will also affect global or regional volume measures in MS: acute inammation and gliosis will increase volume whereas decreased tissue water and inammation due to treatment, dehydration, or other factors, will decrease volume.It is likely that the use of atrophy to measure progressive neurodegeneration in MS will be made less sensitive because of the Dabrafenib volumetric uctuations attributable to inammation.It should also be kept in mind that antiinammatory therapies may reduce brain volume without there having been axonal loss.If such an effect is anticipated, it would seem wise to allow a period of time after receiving such therapy for the antiinammatory volume reduction effect to have occurred before using ongoing atrophy as a presumed measure of axonal loss.The optimal technique for detecting atrophy should be reproducible, sensitive to change, accurate, and practical to implement, although small errors of accuracy are probably insignicant, as long as they are constant between subjects and over time.The two distinct methodological aspects involved in measuring tissue volumes are data acquisition and data analysis.Data analysis methods.Manual outlining or linear measurements provide the simplest approach to measuring changes in volume.An experienced observer is required who is familiar with normal neuroanatomy and pathology.Disadvantages of manual segmentation include operator bias, long analysis time and poor reproducibility when compared with automated techniques.Semiautomated methods improve speed and reproducibility.Many automated methods exist for segmentation of the whole brain.Both single contrast and multispectral data, have been used for wholebrain segmentation.Usually the difference in signal intensity between brain parenchyma and CSF on a singlecontrast acquisition is enough to drive the segmentation process.Segmentation of gray and white matter may also be accomplished with either singlecontrast or multispectral data, although additional sophistication is required to separate the two tissue types.Masking of MS lesions is necessary to avoid their misclassication.Because atrophy is the measurement of change in volume, measurements of absolute volumes at separate time points are not necessarily needed; information may be obtained by looking for differences between serial scans.Nonlinear registration of such scans produces deformation elds that yield information concerning regional and global atrophy.Rigid body registration can be used to track the displacement of the surface of the brain during atrophy.Comparisons between groups of patients are confounded by the presence of substantial intersubject variations in head size that can mask differences attributable to atrophy.There was no change in ventricular volume in the patients with normal imaging.Thus, brain atrophy occurs at the earliest clinical stage of MS.Atrophy measures were available in patients, of whom were placebotreated.Cerebral atrophy has been Alpelisib evaluated from relapsing remitting patients for months before and months following interferon treatment and correlated with other MRI lesion and clinical parameters.

Leave a Reply

You must be logged in to post a comment.