Observer variation in MRI evaluation of patients suspected of lumbar disk herniation.
OBJECTIVE
Our objective was to assess observer variation in MRI evaluation in patients suspected of lumbar disk herniation.


METHODS
Two experienced neuroradiologists independently evaluated 59 consecutive patients with lumbosacral radicular pain. Per patient, three levels (L3-L4 through L5-S1) and the accompanying roots were evaluated on both sides. For each segment, the presence of a bulging disk or a herniation and compression of the root was reported. Images were interpreted twice: once before and once after disclosure of clinical information. Interobserver agreement was expressed as unweighted kappa values.


RESULTS
Without clinical information, interobserver agreement for the presence of herniation or bulging disk was moderate (full agreement, 84%; kappa = 0.63; 95% confidence interval [CI], 0.53-0.72). Of a total of 352 segments evaluated, there was disagreement on 58 segments (17%): bulging disk versus no defect in 26 (7.4%), bulging disk versus herniation in five (1.4%), and hernia versus no defect in 27 (7.7%). With clinical information, twice as many bulging disks were reported but no new herniations were detected. Agreement slightly decreased, but not significantly (full agreement, 77%; kappa = 0.59; 95% CI, 0.49-0.69; p = 0.12).


CONCLUSIONS
On average, more than 50% of interobserver variation in MRI evaluation of patients with lumbosacral radicular pain is caused by disagreement on bulging disks. Knowledge of clinical information does not influence the detection of herniations but lowers the threshold for reporting bulging disks.
van Rijn
Jeroen C
JC
Department of Clinical Epidemiology and Biostatistics, Academic Medical Center, University of Amsterdam, Meibergdreef 9, Amsterdam 1105AZ, The Netherlands.
Klemetsö
Nina
N
Reitsma
Johannes B
JB
Majoie
Charles B L M
CB
Hulsmans
Frans J
FJ
Peul
Wilco C
WC
Stam
Jan
J
Bossuyt
Patrick M
PM
den Heeten
Gerard J
GJ
D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D007405:Intervertebral Disc Displacement / Q000175:diagnosis*; D008159:Lumbar Vertebrae; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D010147:Pain Measurement; D011446:Prospective Studies