Keywords:
Musculoskeletal spine, Neuroradiology spine, MR, Normal variants, Diagnostic procedure, Education and training, Epidemiology
Authors:
K. Luoma1, R. Luukkonen1, T. vehmas1, R. Raininko2; 1Helsinki/FI, 2Uppsala/SE
DOI:
10.1594/ecr2018/C-1415
Aims and objectives
Aims and objectives
Different grading methods have been developed for classifying intervertebral disc degeneration on MRI.
The degenerative MRI grades have been originally determined by comparing MRI slices with histological slices on cadaver studies and with biochemical analyses of tissue samples.
A limited number of disc samples has been used as reference in vitro.
Same criteria are used for subjects at any age and for discs at any level.
MRI grades are chosen assuming that the degenerative process proceeds at the same pace in annulus fibrosus,
nucleus pulposus and endplate.
Thus only a few combinations of degenerative findings are used as grades.
The prevalence of other possible combinations of degenerative grades in general population is not known.
Signal intensity of the disc has usually been assessed in general on T2-weighted sagittal images.
The fibrotic horizontal band in the middle of nucleus,
intra nuclear cleft (INC) or the focal irregular hypointensities in nucleus or in INC have not been separately evaluated or used for classification.
Disc height was found to be higher among middle-aged working men than in healthy young men [1].
Differences in physical loading among subjects may explain that unexpected finding.
Abnormal physical loading seems to affect some but not all degenerative findings above and below a transitional vertebra,
assessed with a detailed classification method of internal disc structure [2].
Part of those findings may thus correlate with age dependent disc degeneration and the other part with some other processes like pathologic,
abnormally early starting or fast progressing degenerative process.
Certain findings have been suggested to associate with genes [3,4].
Modic 1 changes (subchondral signal change representing bone marrow edema) have been found to associate with some fast progressing degenerative findings (decrease of disc height,
increase and decrease of signal intensity of nucleus pulposus and increase of adjacent bony endplate defects) [5-7].
Those findings did not progress at the same pace in annulus fibrosus,
nucleus pulposus,
endplate and subchondral bone but different combinations of findings were found among chronic LBP patients.
Our aim was to study the effect of age and disc level on the morphology of lumbar discs assessed by a detailed classification of internal disc changes on MRI.
The prevalence of combinations of degenerative MRI findings in various anatomic regions is studied to better understand which findings most likely represent a slowly progressing,
possibly age dependent disc degeneration.
The analysis may aid in choosing the best markers for grading disc degeneration in different study populations f.
ex.
in genetic studies.