LABELING THE LUMBAR VERTEBRAL BODIES: IS THERE A PROCESS YOU CAN COUNT ON?

• L Griffin1, M Hoch1, Raz E1, N Perin1, T Naidich2, G Fatterpekar1

• ASNR Electronic Poster• Annual Meeting April 27, 2015, Chicago IL

1NYU Langone Medical Center, New York, NY2The Icahn School of Medicine at Mt. Sinai, New York, NY

BACKGROUND

• Accurate, consistent numbering of the lumbar spine is necessary to communicate the level of pathology

• A reliable way to identify and label spines with lumbosacral transitional vertebrae (LSTV) has not been established

BACKGROUND

• Many features on MRI have been proposed1,2

• Iliolumbar ligament• Disc morphology• Level of anatomic

structures

BACKGROUND

• Research in cadavers suggests a significant difference between the craniocaudal dimensions of the L3-L5 spinous processes3,4

PURPOSE

• Use of spinous process height would be quick and applicable to both CT and MRI

• Determine if craniocaudal height can be used to reliably identify the lumbar vertebrae level in normal spines and those with LSTV

MATERIALS and METHODS• Retrospective review of total spine MRI performed for any clinical reason from

January 2013 through December 2014• Lack of a reported LSTV constituted a “normal” case• LSTV cases were identified using search terms “transitional” “lumbarized” and “sacralized”

• Gold standard: labelling levels from C2 • On sagittal whole body counter sequence, upper and lower spine counter sequences from

C2, landmarks were used if a whole body counter was not available

• Spinous process craniocaudad dimension from T12 – S1 was measured on sagittal T1 weighted sequences

• From superior to inferior cortex, perpendicular to long axis of spinous process

• Differences in dimension were analyzed within the whole group and between the transitional and normal groups

• Interobserver reliability was assessed in a subset of 40 cases

RESULTS• A total of 81 cases were reviewed

• 52 normal, 29 transitional (18 lumbarized L5 and 11 sacralized S1)

• 40 male (49%), age 54 +/- 18 years (range 17 – 92 years)

Table. Comparison of Spinous Process Craniocaudal Dimensions

Normal (52 cases)

Transitional (29 cases)

All (81 cases)

Cases when L5 was smaller than L4

50 (96%) 26 (90%) 76 (94%)

Cases when T12 was smaller than L1

43 (83%) 28 (97%) 71 (88%)

RESULTS

51

01

52

02

53

05

10

15

20

25

30

Normal Lumbarized S1

Sacralized L5

L5

L5

S1

L5

T12

T12

T12

L5 smaller than L4 (p < 0.001 for all)

S1 smaller than L5 for lumbarized cases (p < 0.0001)

T12 smaller than L1 (p < 0.05 for all)

RESULTS

• There was moderate agreement between readers on all cases (kappa 0.60) , normal cases (kappa = 0.54) and sacralized cases (kappa = 0.48), all p < 0.0001

• Substantial agreement was reached in identifying lumbarized cases (kappa 0.73, p < 0.0001)

Table. Subset Reviewed by Three Reviewers

Normal Lumbarized S1 Sacralized L5

Counting from C2 12 18 10

Clinical Report 14 16 10

Reader 1 13 16 11

Reader 2 19 16 5

Reader 3 13 19 8

Example 1: 54YO Male, Suspicion for drop mets

1. Find smallest spinous process

2. Find transition to bulbous spinous processes

LABEL L5

LABEL L1

Confirmed with counting from C2

L5

L1

L2

L3

L4

C2

T1

T12

L1

L2

L3

L4

L5

2. Find transition to bulbous spinous processes

LABEL L5

1. Find smallest spinous process

LABEL L1

Lumbarized S1

LABEL L5

1. Find smallest spinous process

2. Find transition to bulbous spinous processes

LABEL L1

3. Raises possibility of lumbarized S1

C2

T1

T9

T9

L5

L4

L3

L2

L1

Example 2: 17-year-old male with neurofibromatosis type I

L5

L1

L2

L3

L4

Example 3: 63 YO for Follow Up

LABEL L5

1. Find smallest spinous process

2. Find transition to bulbous spinous processes

LABEL L1

3. Sacralized L5

L5

L1L2

L3

L4

C2

T1

L1

L2

L3

L4

L5

Quiz; 56-year-old male with multiple myeloma.

Identify L5

Confirm L1

Check Yourself

T9

T9

CONCLUSIONS

• Identifying the shortest spinous process could be a reliable marker for labelling L5, obtained quickly by visual inspection

• L1 is larger than T12 a majority of the time and can be used to troubleshoot when question of LSTV

• Overall accuracy of the shortest lumbar spinous process correlating with L5 is 94%, which is the same as use of the iliolumbar ligament to identify L55

REFERENCES

1. Hughes RJ, Saifuddin A. Number of Lumbosacral Transitional Vertebrae on MRI: Role of the Iliolumbar Ligaments. AJR AM J Roentgenol 2006: 187: W59-65

2. Tokgoz N, Ucar M, Erdogan AB, et al. Are Spinal or Paraspinal Anatomic Markers Helpful for Vertebral Numbering and Diagnosing Lumbosacral Transitional Vertebrae? Korean J Radiol 2014: 15: 258-66

3. Sun X, Murgatroyd AA, Mullinix KP, et al. Biomechanical and anatomical considerations in lumbar spinous process fixation – an in vitro human cadaveric model. Spine J 2014: 14: 2208-15

4. Cai B, Ran B, Li Q, et al. A morphometric study of the lumbar spinous process in the Chinese population. Braz J Med Biol Res 2014 Oct 24. [Epub ahead of print]

5. Tureli D, Gazanfer E, Baltacioglu F. Is any landmark reliable in vertebral enumeration? A study of 3.0-Tesla lumbar MRI comparing skeletal, neural, and vascular markers. Clinical Imaging 2014: 38: 792-796