Agreement in the interpretation of magnetic resonance images of the lumbar spine.
BACKGROUND
Correlation between clinical features and magnetic resonance imaging (MRI) findings is essential in low-back-pain patients. Most previous studies have analyzed concordance in the interpretation of lumbar MRI among a few radiologists who worked together. This may have overestimated concordance.


OBJECTIVE
To evaluate intra- and interobserver agreement in the interpretation of lumbar MRI performed in an open 0.2 T system.


METHODS
Seven radiologists from two different geographic settings in Spain interpreted the lumbar MRIs of 50 subjects representative of the general Danish population aged 40 years. The radiologists interpreted the images in routine clinical practice, having no knowledge of the clinical and demographic characteristics of the subjects and blinded to their colleagues' assessments. Six of the radiologists evaluated the same MRIs 14 days later, having no knowledge of the previous results. Data on the existence of disc degeneration, high-intensity zones, disc contour, Schmorl nodes, Modic changes, osteophytes, spondylolisthesis, and spinal stenosis were collected in the Nordic Modic Consensus Group Classification form. Intra- and interobserver agreement was analyzed for variables with a prevalence >or=10% and <or=90% by means of the kappa statistic.


RESULTS
Intra- and interobserver agreement was excellent for variables related to Modic changes, and fair to good for disc contour, high-intensity zones, and Schmorl nodes. The evaluations for disc degeneration and osteophytes were found to have fair to good intraobserver agreement and poor interobserver agreement. The agreement for the evaluations of spondylolisthesis and spinal stenosis was not analyzed because they were observed in <10% of reports.


CONCLUSIONS
Images from 0.2 T MRIs appear to lead to good agreement in the reporting of disc contour, high-intensity zones, Schmorl nodes, and, in particular, Modic changes, suggesting that they can possibly be reliably used for clinical research purposes. In contrast, assessment of osteophytes and disc degeneration is not reliable.
Departamento Científico, Fundación Kovacs, Palma de Majorca, Spain. kovacs@kovacs.org
F M
FM
Kovacs
A
A
Royuela
T S
TS
Jensen
A
A
Estremera
G
G
Amengual
A
A
Muriel
I
I
Galarraga
C
C
Martínez
E
E
Arana
H
H
Sarasíbar
R M
RM
Salgado
V
V
Abraira
O
O
López
C
C
Campillo
M T Gil
MT
del Real
J
J
Zamora
D000328:Adult; D003718:Denmark; D005260:Female; D006801:Humans; D008159:Lumbar Vertebrae / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods / Q000706:statistics & numerical data*; D008297:Male; D015588:Observer Variation; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D013030:Spain; D013122:Spinal Diseases / Q000175:diagnosis*; D016683:Supine Position