RADIOLOGICAL 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
DATE: Thursday: December 04, 2003
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.
METHODS AND MATERIALS
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