SOCIETY OF NORTH AMERICA 2003
(RSNA): Scientific Papers
Neuroradiology/Head and Neck (My Aching Back)
MEASUREMENT OF DIURNAL
VARIATION IN INTERVERTEBRAL DISC HEIGHT IN NORMAL INDIVIDUALS:
A STUDY COMPARING SUPINE WITH ERECT MRI
DATE: Thursday: December
START TIME: 11:30 AM
END TIME: 11:37 AM
LOCATION: ROOM N228
Francis W. Smith, MD
University of Aberbeen, Scotland, U.K.
Waseem Bashir MBBS
Yoichiro Hirasawa MD
Malcolm Pope PhD
Keywords: Spine, MR
Circadian variation in human stature has been recognized since
1726.Diurnal height changes result from gravitational forces
and are believed to result from changes in the intervertebral
disc. With the availability of an MRI scanner which is capable
of imaging in the erect as well as supine positions, it is
now possible to study alterations in the appearances of the
upright spine for the first time. This study measures disc
height changes between morning and evening in both the erect
and supine positions.
32 male volunteers with no history of either low back pain
or sciatica were studied using a 0.6Tesla indominitable pMRI
scanner (FONAR). Each indiviual was examined supine and erect
within 30 minutes of rising in the morning and again between
eight and 9 hours later at the end of a normal working day.
Each of the five intervertebral discs were measured using
(a+p)/2, where a = anterior and p = posterior disc height.
Measurements and interobserver reproducibility were performed
independently by a radiolgist and an orthopaedic surgeon.
Measurement results were analysed with one way ANOVA and multiple
comparison post tests.
The cumulative loss of lumbar disc height for the five discs
was between 7.70 - 8.09mm in the erect position and between
7.29 - 7.52mm in the supine position.
The length of the lumbar spine is about one third of the total
body height and the intervertebral discs provide about 25%
of this length. This study is unique in that it allows the
spine to be assessed in the erect "naturally loaded"
position. Given that the observed normal diurnal loss of height
has been shown to be 17.00mm, one would expect that the loss
over the lumbar region to be 8.5mm. The difference between
this expected loss and our findings is accounted for by the
alteration in lumbar lordosis between the erect and supine