Bone Morphology and Modic Classifications
– William Morgan, DC
VERTEBRAL BODY EDEMA IS A COMMON FINDING on magnetic resonance imaging (MRI). Though degenerative changes such as bony edema may equate to unimportant background noise for the busy clinician, recent studies have found that vertebral marrow edema is clinically significant and can be a progressive condition.
Michael T. Modic, MD, identified and published his findings on vertebral bony marrow changes in the journal Radiology in 1988.1, 2 Since that time these findings and his grading criteria have borne his name. Modic changes represent MRI observations of vertebral marrow and endplate changes. These changes have been linked to trauma, disc disruption and degeneration. More studies are currently underway to identify the clinical significance of this finding and to fully understand its progression.
The vertebral body has a dense outer barrier of cortical bone that is particularly dense at the vertebral endplates. Within this tough outer shell lies the subcortical marrow cavity. This cancellous bone is porous and less dense. It is normal for this porous bone to contain fatty marrow. The T1- and T2-weighted MR images will reflect the presence of normal fatty marrow with a supportive bony matrix. When edema is present in the marrow, it is characterized by an influx of water content: T1-weighted images show loss of signal (hypointense signal in the marrow), while T2-weighted images will demonstrate an increased (hyperintense) signal.
Degenerative disc disease (DDD) without Modic changes is a relatively insidious and not particularly painful condition, whereas DDD with Modic changes is much more frequently associated with pain.3,4, 5, 6, 7 Type 1 Modic changes show bony edema and inflammation and are strongly associated with back pain. Emerging evidence indicates there is a progressive nature to Modic changes. The bony edema of type I Modic changes may progress to type 2, and type 2 may progress to type 3.8, 9, 10
Modic Types
The Modic classification system is a method for categorizing vertebral body and endplate findings on MRI. Here are the three types:
TYPE 1. Type 1 Modic changes are characterized by high water content that is indicative of inflammation and edema. They are manifested as hypointense (dark) on T1-weighted MRI and hyperintense (bright) on T2-weighted images.
TYPE 2. Modic type 2 changes identify yellow fatty infiltration into the vertebral body. On T1 images, the fatty infiltration of type 2 Modic changes will appear hyperintense, and on T2-weighted images, they will appear hyperintense or isointense.
TYPE 3. Modic type 3 changes are less common than types 1 and 2 with less scientific investigation. Modic type 3 is identified by decreased signal or hypointense on both T1- and T2-weighted MRIs. These findings can typically be correlated with sclerosis on plain film X-ray.
Conclusion
Modic changes can have strong clinical significance. Type 1 Modic changes have been strongly associated with deep bony pain and inflammation whereas type 2 and type 3 Modic changes are less likely to be associated with refractory pain and tend to be more stable.
References
1. Modic MT, Steinberg PM, Ross JS, et al. Degenerative disc disease: Assessment of changes in vertebral body marrow with MR imaging. Radiology 1988;166:193-9.
2. Modic MT, Ross JS. Lumbar degenerative disk disease. Radiology 2007 Oct;245 (1): 43-61.
3. Toyone T, Takahashi K, Kitahara H, et al. Vertebral bone-marrow changes in degenerative lumbar disc disease: an MRI study of 74 patients with low back pain. J Bone Joint Surg Br 1994;76:757–64.
4. Mitra D, Cassar-Pullicino VN, McCall IW. Longitudinal study of vertebral type-1 end-plate changes on MR of the lumbar spine. Eur Radiol 2004;14:1574–81.
5. Kuisma M, Karppinen J, Niinimäki J, et al. Modic changes in endplates of lumbar vertebral bodies: prevalence and association with low back and sciatic pain among middle-aged male workers. Spine 2007;32:1116–22.
6. Albert HB, Manniche C. Modic changes following lumbar disc herniation. Eur Spine J 2007;16:977–82.
7. Modic MT. Modic type 1 and type 2 changes. J Neurosurg Spine 2007;6:150–51.
8. Braithwaite I, White J, Saifuddin A, et al. Vertebral end-plate (Modic) changes on lumbar spine MRI: correlation with pain reproduction at lumbar discography. Eur Spine J 1998;7:363–68.
9. Kuisma M, Karppinen J, Niinimaki J, et al. A three-year follow-up of lumbar spine endplate (Modic) changes. Spine 2006;31:1714–18.
10. Modic MT, Steinberg PM, Ross JS, et al. Degenerative disk disease: assessment of changes in vertebral body marrow with MR imaging. Radiology 1988;166:193–99.
For more instruction on how to identify Modic changes on MRI, consider Dr. Morgan’s eBook: The Lumbar MRI in Clinical Practice available through LuLu.com at www.lulu.com/shop/williammorgan/the-lumbar-mri-inclinicalpractice/ebook/product-21732729.html.