Validation of multisociety combined task force definitions of abnormal disk morphology.
OBJECTIVE
The multisociety task force descriptively defined abnormal lumbar disk morphology. We aimed to use their definitions to provide a higher level of evidence for the validation of MR imaging in the evaluation of this pathology in patients who have undergone diskectomy by retrospectively classifying their preoperative MRI.


METHODS
This retrospective, institutional review board-approved study included 54 of 86 consecutive patients (47 men; average age, 44 years) enrolled in an ongoing prospective trial of surgically treated lumbar disk herniation who had preoperative MRI and documented intraoperative classification of the abnormal disk as protrusion, extrusion, or sequestration by the treating surgeon. Preoperative MRI was classified by 2 blinded radiologists; discrepancies were resolved by a third reader. Statistical analysis of interobserver agreement and imaging compared with surgical findings was performed.


RESULTS
The readers disagreed on only 1 of the 54 cases. The third reader resolved the disagreement. Eight protrusions and 46 extrusions were found on imaging, with no sequestrations. At surgery, there were 13 protrusions and 40 extrusions, with 2 of the extrusions also containing sequestrations; the remaining case had only sequestration. There were 16 discrepancies between imaging and surgery, resulting in 70% agreement.


CONCLUSIONS
This study, which was intended to validate the multisociety combined task force definitions of abnormal disk morphology by using MR imaging with a surgical criterion standard, found 70% agreement between imaging diagnosis and surgical findings. Although reasonable, this finding highlights differences that often exist between intraoperative and preoperative imaging findings of lumbar disk herniation.
From the Departments of Radiology (C.H.C., L.H., A.A.Z.) ccho81@partners.org.
C H
CH
Cho
From the Departments of Radiology (C.H.C., L.H., A.A.Z.).
L
L
Hsu
Orthopedic Surgery (M.L.F., D.A.L., M.B.H., C.M.B.), Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts.
M L
ML
Ferrone
Orthopedic Surgery (M.L.F., D.A.L., M.B.H., C.M.B.), Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts.
D A
DA
Leonard
Orthopedic Surgery (M.L.F., D.A.L., M.B.H., C.M.B.), Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts.
M B
MB
Harris
From the Departments of Radiology (C.H.C., L.H., A.A.Z.).
A A
AA
Zamani
Orthopedic Surgery (M.L.F., D.A.L., M.B.H., C.M.B.), Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts.
C M
CM
Bono
D000328:Adult; D026683:Advisory Committees / Q000592:standards*; D000368:Aged; D005260:Female; D006801:Humans; D007403:Intervertebral Disc / Q000473:pathology*; D007405:Intervertebral Disc Displacement / Q000473:pathology*; D008159:Lumbar Vertebrae / Q000473:pathology; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D012189:Retrospective Studies