1) Description of Measurement

T1 hypointensity refers to focal or diffuse low signal intensity within the cervical spinal cord on T1-weighted MRI. When present, it is considered a marker of chronic spinal cord injury, most commonly representing myelomalacia, cord atrophy, gliosis, or irreversible ischemic damage.

In the context of cervical spinal stenosis or degenerative cervical myelopathy (DCM), T1 hypointensity is associated with longstanding compression, advanced disease, and poorer neurologic recovery compared with patients who demonstrate T2 hyperintensity alone.

2) Instructions to Measure

• Select a mid-sagittal T1-weighted MRI sequence with adequate visualization of the cervical spinal cord.

• Identify the signal intensity of normal spinal cord at levels above and below the area of interest to establish a baseline reference.

•  Evaluate the spinal cord at the level(s) of compression for:

• Focal or linear regions of decreased T1 signal within the cord parenchyma

• Signal that is clearly darker than adjacent normal cord and not attributable to artifact

• Confirm that the hypointense signal:

• Corresponds anatomically to the region of chronic compression

•  Persists across adjacent slices, when available

•  Record the finding as:

• T1 hypointensity: Present (across multiple levels?)

• T1 hypointensity: Absent

3) Normal vs. Pathologic Ranges

• Normal cord signal or potentially reversible injury: No T1 hypointensity

• Chronic cord injury: Focal T1 hypointensity; suggests early myelomalacia

• Advanced chronic myelopathy: Diffuse or multilevel T1 hypointensity; cord atrophy

Key points:

• T1 hypointensity is always pathologic

• Indicates irreversible spinal cord damage in most cases

• Strongly associated with poor postoperative neurologic recovery

4) Important References

Morishita Y, Naito M, Hymanson HJ, et al. The relationship between the cervical spinal canal diameter and the pathological changes in the cervical spine. Eur Spine J. 2009; Jun; 18(6):877-83.

Tetreault L, Palubiski LM, Kryshtalskyj M, et al. Significant Predictors of Outcome Following Surgery for the Treatment of Degenerative Cervical Myelopathy: A Systematic Review of the Literature. Neurosurg Clin N Am. 2018 Jan;29(1):115-127.e35.

Badhiwala JH, Wilson JR, Fehlings MG. Global burden of traumatic brain and spinal cord injury. Lancet Neurol. 2019 Jan;18(1):24-25.

Nouri A, Martin AR, Mikulis D, et al. Magnetic resonance imaging assessment of degenerative cervical myelopathy: a review of structural changes and measurement techniques. Neurosurg Focus. 2016 Jun;40(6):E5.

5) Other info....

T1 hypointensity should always be interpreted in conjunction with T2 hyperintensity:

• T2 hyperintensity alone → edema or potentially reversible injury

• T1 hypointensity + T2 hyperintensity → chronic, irreversible damage

Presence of T1 hypointensity is a negative prognostic factor for:

• Neurologic recovery after decompression

• Functional improvement (JOA, mJOA, NDI)

Absence of T1 hypointensity does not exclude clinically significant myelopathy

Particularly useful when combined with:

• T2 hyperintensity length

• Cord cross-sectional area (CSA)

• Compression ratio

• Maximum spinal cord compression (MSCC)