J Korean Neurosurg Soc.  2017 Jul;60(4):465-470. 10.3340/jkns.2016.1010.004.

Correlation between MRI Grading System and Surgical Findings for Lumbar Foraminal Stenosis

  • 1Department of Neurosurgery, Gachon University Gil Medical Center, Incheon, Korea. ns-ay@hanmail.net
  • 2Department of Radiology, Nanoori Hospital, Seoul, Korea.


Magnetic resonance imaging (MRI) grading systems using sagittal images are useful for evaluation of lumbar foraminal stenosis. We evaluated whether such a grading system is useful as a diagnostic tool for surgery.
Between July 2014 and June 2015, 99 consecutive patients underwent unilateral lumbar foraminotomy for lumbar foraminal stenosis. Surgically confirmed foraminal stenosis and the contralateral, asymptomatic neuroforamen were assessed based on a 4-point MRI grading system. Two experienced researchers independently evaluated the MR sagittal images. Interobserver agreement and intraobserver agreement were analyzed using κ statistics.
The mean age of patients (54 women, 45 men) was 62.5 years. A total of 101 levels (202 neuroforamens) were evaluated. MRI grades for operated neuroforamens were as follows: Grade 0 in 0.99%, Grade 1 in 5.28%, Grade 2 in 14.85%, and Grade 3 in 78.88%. Interobserver agreement was moderate for operated neuroforamens (κ=0.511) and good for asymptomatic neuroforamens (κ=0.696). Intraobserver agreement by reader 1 for operated neuroforamens was good (κ=0.776) and that for asymptomatic neuroforamens was very good (κ=0.831). In terms of lumbar level, interobserver agreement for L5-S1 (κ=0.313, fair) was relatively lower than the other level (κ=0.804, very good).
MRI grading system for lumbar foraminal stenosis is thought to be useful as a diagnostic tool for surgery in the lumbar spine; however, it is less reliable for symptomatic L5-S1 foraminal stenosis than for other levels. Thus, various clinical factors as well as the MRI grading system are required for surgical decision-making.


Spinal stenosis; Lumbar vertebrae; Magnetic resonance imaging; Foraminotomy; Surgery

MeSH Terms

Constriction, Pathologic*
Lumbar Vertebrae
Magnetic Resonance Imaging*
Spinal Stenosis


  • Fig. 1 Four-point-scale for grading of lumbar foraminal stenosis in sagittal MRI suggested by Lee et al.9). A: Grade 0 (normal). Sagittal cross section through foramen shows normal neuroforamen. B: Grade 1 (mild foraminal stenosis). Sagittal cross section through foramen shows perineural fat obliteration in two opposing directions (vertical or transverse, arrows). C: Grade 2 (moderate foraminal stenosis). Sagittal cross section through foramen shows perineural fat obliteration in four directions (arrows). D: Grade 3 (severe foraminal stenosis). Sagittal cross section through foramen shows morphologic changes in the nerve root. MRI: magnetic resonance imaging.

  • Fig. 2 T1-weighted sagittal image of a 44-year-old man with left lower extremity pain. A: Sagittal MR image shows Grade 3 foraminal stenosis at left foramen of the L3–L4 level. B: Sagittal MR image shows Grade 0 of normal neuroforamen at right foramen of the L3–L4 level. MR: magnetic resonance.



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