title: Association between visual degeneration of intervertebral discs and the apparent diffusion coefficient.
abstract: The value of apparent diffusion coefficient (ADC) measurements in intervertebral disc has been studied because ADC provides an estimate of free diffusion of unbound water and could be used as a quantitative tool to estimate degenerative changes. However, the challenging nature of diffusion imaging of spine and limited numbers of subjects in earlier studies has produced contradictory findings. We aimed to determine the relation between ADC and visual degenerative changes in lumbar intervertebral discs in a sufficiently large homogeneous study group. Lumbar spines of 228 volunteer middle-aged men were MR imaged at 1.5 T including anatomic and diffusion-weighted imaging. ADC values, T2 signal intensity and height, and width of the three lowest lumbar intervertebral discs were measured and disc degeneration visually graded. The calculated average ADC of 530 measured discs was 2.01 x 10(-3) mm(2)/s+/-0.29 (+/-S.D.). The reduction in ADC between visually normal and moderately degenerated discs was 4%. Severely degenerated discs showed 5% larger ADC values than normal discs, presumably due to free water in cracks and fissures of those discs. T2 signal intensity of the disc was significantly correlated with the ADC values, whereas other measured parameters did not show correlation. There was no evident difference in ADC between the studied anatomic lumbar levels. Because there is considerable overlap between ADC values of normal and degenerated discs, we conclude that ADC measurements of intervertebral discs, at least with current technology, have limited clinical value.
authors.affiliation: Department of Diagnostic Radiology, Oulu University Hospital, 90029 Oulu, Finland. jaakko.niinimaki@oulu.fi
authors.forename: Jaakko
authors.initials: J
authors.lastname: Niinimäki
authors.forename: Arto
authors.initials: A
authors.lastname: Korkiakoski
authors.forename: Outi
authors.initials: O
authors.lastname: Ojala
authors.forename: Jaro
authors.initials: J
authors.lastname: Karppinen
authors.forename: Jyrki
authors.initials: J
authors.lastname: Ruohonen
authors.forename: Marianne
authors.initials: M
authors.lastname: Haapea
authors.forename: Raija
authors.initials: R
authors.lastname: Korpelainen
authors.forename: Antero
authors.initials: A
authors.lastname: Natri
authors.forename: Osmo
authors.initials: O
authors.lastname: Tervonen
mesh_terms: D000328:Adult; D000465:Algorithms; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D007403:Intervertebral Disc / Q000473:pathology*; D007405:Intervertebral Disc Displacement / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity