Detailed review
*Title: Assessment of Magnetic Resonance Imaging in the diagnosis of lumbar
spine foraminal stenosis -A surgeon's perspective
요추 추간공 협착증 진단에서의 MRI의 측정 -외과의의 관점
*Author: Naftaly Attias, MD, Anne Hayman, MD, John A. Hipp, PhDz Philip Noble, PhD,
and Stephen I. Esses, MD
*Bibliography: J Spinal Disord Tech 2006;19:249-256
Study Design: A 2-part cadaveric study
Introduction:
1. Lumbar spine foraminal stenosis (LSFS) incidence >> 8% ~ 11%
2. Limitations of MRI itself for the diagnosis of LSFS
3. Not well understood about the effect of the variability on assessing
LSFS
1) Various Techniques
2) Various Observers
4. No control over the final quality, or quantity of images provided to
the surgeons
5. Glenn's words for size of a lesion in spine
>> 1) normal, 2) slight,
3) mild, 4)moderate, 5) sever
6. Wildermuth et al's semi-quantitative classification system for
grading LSFS
1) On the basis of 'Open' MRI
findings
2) Grade 0 >> foramina
without pathology
3) Grade 1 >> slight
foraminal stenosis
4) Grade 2 >> marked
foraminal stenosis
5) Grade 3 >> advanced
stenosis
7. About this study
1) 2-part study to investigate
the use of MRI in diagnosing LSFS
① Take
MRIs of 3 cadavers in 3 centers, 8 spine surgeons to assess
>> Reliability of
Wildermuth semiquantitative classification system
>> Variability in MRI
examinations carried out in different institutions
② Compare MRI measurements vs. cadaveric slices
to assess
>> Differences between
measurements from MRI vs. cadaveric specimens
Methods:
1. Fresh, frozen human lumbar spines (3 cadavers)
2. Examined with 3 different clinical MRI systems
3. Graded foramina by 8 surgeons on the basis of Wildermuth
semiquantitative way
4. MRI measurements
1) Foraminal height
2) Superior foraminal width
3) Middle foraminal width
4) Posterior disc height
5. Specimen measurements
1)
Foraminal height
2)
Superior foraminal width
3)
Middle foraminal width
Results, Part 1:
1. 9set MRI scan review/total 72 foramina per
one observer
2. Grading
0)
Grade 0 >> 222 foramina (39%)
1)
Grade 1 >> 201 foramina (35%)
2)
Grade 2 >> 127 foramina (22%)
3)
Grade 3 >> 26 foramina (04%)
4) P =
0.15, nearly significant on the basis of paired t-tests
3. Level of interobserver agreement
0) k
grade 0 >> 0.13
1) k
grade 1 >> -0.01
2) k
grade 2 >> 0.06
3) k
grade 3 >> 0.11
4)
combined >> 0.07
5) Most
observers underestimated LSFS grade as compared with grading specimens.
6)
Preferred Method to assess the foramen >> T1 sagittal sequence
Results, Part 2:
1. MRI measurements
1) Foraminal height >>
14.78mm (SD 4.53)
2) Superior foraminal width
>> 7.73mm (SD 1.77)
3) Middle foraminal width
>> 3.79mm (SD 1.68)
4) Posterior disc height >>
5.55mm (SD 1.63)
5) Correlation between MRI
measurements and Actual dimensions in specimens >> Poor
2. Specimen measurements
1) Measured 24 foramina and
Graded according to Wildermuth classification
Grade 0 >> 8 (33%)
Grade 1 >> 3 (12%)
Grade 2 >> 10 (42%)
Grade 3 >> 3 (12%)
2) Measurments of foraminal
size
Foraminal height >>
16.12mm (SD -3.11)
Proximal foraminal width
>> 8.99mm (SD -2.43)
Middle foraminal width
>> 4.76mm (SD -2.80)
Conclusion:
The parameters associated with the grade of
stenosis assigned to the foramen were as follows:
(1) the observer doing the
grading
(2) the place it was imaged
(3) the location of the foramen.
There was poor correlation between measurements
of the foramina carried out on MRI and the specimens.
