INTEROBSERVER RELIABILITY OF DETECTING LUMBAR INTERVERTEBRAL DISC HIGH-INTENSITY ZONE ON MAGNETIC-RESONANCE-IMAGING AND ASSOCIATION OF HIGH-INTENSITY ZONE WITH PAIN AND ANULAR DISRUPTION
Bmt. Smith et al., INTEROBSERVER RELIABILITY OF DETECTING LUMBAR INTERVERTEBRAL DISC HIGH-INTENSITY ZONE ON MAGNETIC-RESONANCE-IMAGING AND ASSOCIATION OF HIGH-INTENSITY ZONE WITH PAIN AND ANULAR DISRUPTION, Spine (Philadelphia, Pa. 1976), 23(19), 1998, pp. 2074-2080
Study Design. Retrospective analysis of a spine imaging center's recor
ds of patients with chronic low back pain referred by tertiary care fa
cilities. Objectives. 1) To assess the interobserver reliability of de
tecting lumbar intervertebral disc high-intensity zone on T-2-weighted
magnetic resonance imaging, and 2) to assess the relation between hig
h-intensity zone and discography or post-computed tomography in sympto
matic patients with low back pain. Summary of Background Data. Two of
the three previous studies on this subject found an association betwee
n high-intensity zone and the presence of Grade 4 anular disruption wi
th discographic reproduction of patients' exact low back pain. Methods
. Records of patients with low back pain who had undergone lumbar spin
e discography injection and post-computed tomography from June 1995 to
August 1996 were reviewed. Two independent observers were asked to id
entify the presence of an high-intensity zone from the T12-L1 disc to
L5-S1 on T-2-weighted magnetic resonance images. With this data, inter
observer reliability was assessed with the kappa statistic. Concordant
high-intensity zone results were then compared with the Dallas Discog
ram rating for anular disruption and to patients' subjective pain resp
onse to discography injection. With this data, the sensitivity, specif
icity, and predictive values of high-intensity zone for detecting disc
disruption and pain response were calculated. Results. The interobser
ver reliability for detecting a high-intensity zone in a given disc wa
s fair to good (kappa = 0.57; 95% confidence interval = 0.44, 0.70). T
he sensitivity of high-intensity zone for detecting Grade 4 anular dis
ruption and exact pain was poor (31%) but its specificity was relative
ly high (90%). The positive predictive value of a high-intensity zone
was low (40%) for a severely disrupted and exactly painful disc. Concl
usions. The interobserver reliability of detecting a high-intensity zo
ne and the positive predictive value of the presence of a high-intensi
ty zone for detecting a severely disrupted and exactly painful disc we
re much lower than previous studies have shown. The relatively low pos
itive predictive value may be attributable to differences in sample ch
aracteristics or procedural variations, or suggest that a high-intensi
ty zone is not indicative of exactly painful internal intervertebral d
isc disruption.