Degeneration and height of cervical discs classified from MRI compared with precise height measurements from radiographs.
METHODS
Descriptive study comparing MRI classifications with measurements from radiographs.


OBJECTIVE
1. Define the relationship between MRI classified cervical disc degeneration and objectively measured disc height. 2. Assess the level of inter- and intra-observer errors using MRI in defining cervical disc degeneration.


BACKGROUND
Cervical spine degeneration has been defined radiologically by loss of disc height, decreased disc and bone marrow signal intensity and disc protrusion/herniation on MRI. The intra- and inter-observer error using MRI in defining cervical degeneration influences data interpretation. Few previous studies have addressed this source of error. The relation and time sequence between cervical disc degeneration classified by MRI and cervical disc height decrease measured from radiographs is unclear.


METHODS
The MRI classification of degeneration was based on nucleus signal, prolaps identification and bone marrow signal. Two neuro-radiologists evaluated the MR-images independently in a blinded fashion. The radiographic disc height measurements were done by a new computer-assisted method compensating for image distortion and permitting comparison with normal level-, age- and gender-appropriate disc height.


CONCLUSIONS
1. Progressing disc degeneration classified from MRI is on average significantly associated with a decrease of disc height as measured from radiographs. Within each MRI defined category of degeneration measured disc heights, however, scatter in a wide range. 2. The inter-observer agreement between two neuro-radiologists in both defining degeneration and disc height by MRI was only moderate. Studies addressing questions related to cervical disc degeneration should take this into consideration.
Kolstad
Frode
F
National Centre of Spinal Disorders, Norwegian University of Science and Technology, University Hospital of Trondheim, 7006 Trondheim, Norway. frode.kolstad@medisin.ntnu.no
Myhr
Gunnar
G
Kvistad
Kjell Arne
KA
Nygaard
Oystein P
OP
Leivseth
Gunnar
G
D000328:Adult; D002574:Cervical Vertebrae / Q000000981:diagnostic imaging / Q000473:pathology*; D005260:Female; D006801:Humans; D007403:Intervertebral Disc / Q000000981:diagnostic imaging / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011859:Radiography; D013122:Spinal Diseases / Q000175:diagnosis* / Q000000981:diagnostic imaging