Imaging method | Author | Site of measurement | Level, where measured (measurement points) | Definition of stenosis (cut-off values) |
---|---|---|---|---|
MRI | Â | Â | Â | Â |
 |  | Antero-posterior diameter of spinal canal |  |  |
 | Fukusaki [22] |  | Not reported | < 15 mm |
 | Koc [23] |  | Not reported | < 12 mm |
 |  | Mid-sagittal diameter of thecal sac |  |  |
 | Herzog [15] |  | Midbody of each vertebra | Compression of thecal sac area in % of normal mid-sagittal diameter: Grade 1: anterior < 15% posterior < 10% Grade 2: anterior 15 - 30% posterior 10 - 20% Grade 3: anterior > 30% posterior > 20% |
 |  | Cross-sectional area of dural tube or sac |  |  |
 | Hamanishi [24] |  | Intervertebral levels: L2/3, L3/4, L4/5 | < 100 mm2, at more than two of three intervertebral levels |
 | Mariconda [25] |  | Not reported | < 130 mm2 |
 | Laurencin [26] |  | Motion segment: Intervertebral disc level coincident with flexible joint; Stable segment: Level coincident with the mid-pedicle unaffected by stenosis | Stenosis ratio: Cross-sectional area of dural sac of motion segment divided by stable segment cross-sectional dural sac area: Level: L3-L4 < 0.66 L4-L5 < 0.62 L5-S1 < 0.73 |
 |  | Ligamentous interfacet distance |  |  |
 | Herzog [15] |  | Distance between the innner surface of flaval ligaments on a line connecting the joint space of facet joints at the level of the intervertebral disc | < 10 mm (L2 - L3) < 10 mm (L3 - L4) < 12 mm (L4 - L5) < 13 mm (L5 - S1) |
 |  | Transverse diameter of spinal canal |  |  |
 | Koc [23] |  | Not reported | < 15 mm |
 | Ullrich [27] |  | 4 zones of measurement: upper, middle, lower zone of vertebral body and disk space | < 16 mm |
CT | Â | Â | Â | Â |
 |  | Antero -posterior diameter of spinal canal |  |  |
 | Bolender [28] |  | 5 mm intervals from L2 to L5 | < 13 mm |
 | Haig [4] |  | Not reported | ≤ 11.95 mm |
 | Lee [29] |  | Not reported | < 15 mm (suggesting narrowing) < 10 mm (usually diagnostic) |
 | Ullrich [27] |  | Four zones of measurement: Upper, middle, lower zone of vertebral body and disk space | < 11.5 mm |
 | Verbiest [30] |  | Not reported | < 12 mm (relative) < 10 mm (absolute) |
 |  | Antero-posterior diameter of dural sac |  |  |
 | Kalichman [3] |  | Midvertebral body level | 10 - 12 mm (relative) < 10 mm (absolute) |
 | Herzog [15] |  | Midbody of each vertebra | Compression of thecal sac area in % of normal mid-saggital diameter: Grade 1: anterior < 15% posterior < 10% Grade 2: anterior 15 - 30% posterior 10 - 20% Grade 3: anterior > 30% posterior > 20% |
 | Jönsson [31] |  | Disc level | ≤ 10 mm |
 |  | Cross-sectional area of dural sac |  |  |
 | Bolender [28] |  | 5 mm intervals from L2 to L5 | 100 - 130 mm2 (early stenosis) < 100 mm2 (present stenosis) |
 | Laurencin [26] |  | Motion segment: Intervertebral disc level coincident with flexible joint stable segment: Level coincident with the mid-pedicle unaffected by stenosis | Stenosis ratio: Area of motion segment divided by stable segment area Level: L3-L4 < 0.66 L4-L5 < 0.62 L5-S1 < 0.73 |
 | Schönström [32] |  | On each CT scan slice | < 100 mm2 |
 | Schönström [33] |  | Not reported | 75 - 100 mm2 (moderate) < 75 mm2 (severe) |
 | Ullrich [27] |  | 4 zones of measurement: Upper, middle, lower zone of vertebral body and disk space | < 145 mm2 |
 |  | Ligamentous interfacet distance |  |  |
 | Herzog [15] |  | Intervertebral disc level | < 10 mm (L2-L3) < 10 mm (L3-L4) < 12 mm (L4-L5) < 13 mm (L5-S1) |
 | Wilmink [34] |  | Pedicular, infrapedicular and/or disc level | < 11 mm (L4-L5) |
Myelography | Â | Â | Â | Â |
conventional | Â | Antero-posterior diameter of contrast column | Â | Â |
 | Airaksinen [35] |  | Narrowest point | > 12 mm 10 - 12 mm < 10 mm Subtotal block Total block |
 | Bolender [28] |  | Intervertebral level | < 13 mm |
 | Herno [36] |  | Not reported | < 12 mm |
 | Jönsson [31] |  | Disc level | ≤ 10 mm |
 | Sortland [37] |  | Disc level | < 10.5 mm (lower limit) < 5.5 - 7 mm (considerable) |
 | Verbiest [38] |  | Superior and inferior boarders of the laminae | 10 - 12 mm (relative) < 10 mm (absolute) |
Myelo-CT | Mariconda [25] | Â | Not reported | < 130 mm2 |