Intramedullary Lesion, T1 Hyperintense

Lubdha M. Shah, MD

DIFFERENTIAL DIAGNOSIS

Common

Contusion-Hematoma, Spinal Cord
Tumor Hemorrhage/Proteinaceous Cyst
- Ependymoma, Cellular, Spinal Cord
- Astrocytoma, Spinal Cord
- Metastases, Spinal Cord
Cavernous Malformation, Spinal Cord

Less Common

Dermoid and Epidermoid Tumors
Lipoma
Infection, Cryptococcoma, Tuberculoma
Melanocytoma

Rare but Important

Intramedullary AVM

ESSENTIAL INFORMATION

Key Differential Diagnosis Issues

T1 hyperintensity can be due to hemorrhage, fat, melanin
Look for associated vertebral body or neural arch abnormalities & mass effect on regional structures

Helpful Clues for Common Diagnoses

Contusion-Hematoma, Spinal Cord
- T1 hyperintensity due to methemoglobin
  - Early T2 hypointensity caused by deoxyhemoglobin in the local hypoxic state of the injured segment
- ± Traumatic disc herniation & vascular injury
- Increase in spinal cord edema during the early period after injury & comparatively static intramedullary hemorrhage
Ependymoma, Cellular, Spinal Cord
- Enhancing cord mass with hemorrhage
- Fusiform cord enlargement with central canal widening in 20%
- Polar or intratumoral cyst (50-90%)
- More often central growth pattern
- More often in the lower thoracic cord
Astrocytoma, Spinal Cord
- Cord expansion
  - Multisegmental, usually < 4 segments
  - Holocord involvement more often with pilocystic astrocytoma
  - Can be asymmetric or exophytic
- Minority of cases T1 hyperintensity due to methemoglobin
- Enhancement is characteristic
  - Mild ⇒ intense, partial ⇒ total, infiltrating ⇒ sharply delineated
- ± Cyst/syrinx (slightly hyperintense to CSF)
Metastases, Spinal Cord
- Hemorrhagic mets, such as thyroid & melanoma metastases
  - Growth of primary spinal melanoma if slower & survival is longer
- Focal enhancement
Cavernous Malformation, Spinal Cord
- Speckled heterogeneous lesion with blood products of varying ages
  - T2 hypointense rim 2° hemosiderin
  - Minimal to no enhancement
- Lesions abut the pial surface
- Angiographically occult
- Clinical presentation ranges from acute neurological decline 2° hemorrhage to chronic progressive myelopathy due to microhemorrhages & gliotic reaction to blood products

Helpful Clues for Less Common Diagnoses

Dermoid and Epidermoid Tumors
- Dermoid
  - Well-demarcated isodense mass ± foci of fat signal/density & calcification
  - Fat T1 hyperintensity is most specific for dermoid but least common
  - Congenital lesion presenting in young patients
- Epidermoid
  - Hyperintense on DWI, T1 isointense to CSF, mildly T2 hyperintense
  - Acquired or congenital, slower growing, present in 3rd to 5th decade
- Extramedullary (60%) > intramedullary (40%)
- Mild peripheral enhancement; however, more intense enhancement if infected
Lipoma
- Homogeneously T1 hyperintense intradural nonenhancing mass
- Intradural lipoma can invaginate into the cord substance
  - Weakness & sensory abnormality at lesion level
  - Normal overlying skin
  - ± Canal widening & dysraphism
- Terminal lipoma can tether the cord with extension through dorsal dysraphism into subcutaneous fat
  - Tethered cord syndrome: Bowel/bladder dysfunction, lower extremity motor/sensory abnormality
  - Cutaneous stigmata frequently seen, foot deformity, scoliosis
  - ± Syrinx
Infection, Cryptococcoma, Tuberculoma
- Tuberculoma
  - Iso-/hyperintensity on T1WI at site of granuloma
  - Iso-/hypointense T2 rim with hyperintense center (caseous necrosis), surrounding hyperintense edema
- Cryptococcus has a respiratory entry
  - CNS manifestation (meningitis/meningoencephalitis) most common because CSF does not have anticryptococcal factors present in serum
  - Arachnoiditis ± mass lesions, intramedullary mass lesions (abscess or granuloma), extradural lesion
  - Slightly T1 hyperintense (fibrosis & inflammatory cellular infiltrates), T2 hypointense with hyperintense focus & surrounding hyperintense edema
  - Intense solid or ring-like enhancement
Melanocytoma
- Primary pigmented neoplasm, involving cord or meninges
  - Can be locally invasive
- T1/T2 shortening by proton-proton dipole-dipole interaction
- Heterogeneous enhancement
- Highest concentration of melanocytes occurs in the spinal leptomeninges in the upper cervical level
- Meningiomas & schwannomas may RARELY demonstrate T1 hyperintensity due to melanin

Helpful Clues for Rare Diagnoses

Intramedullary AVM
- Prominent vascular flow voids leading to & from high flow lesion
  - Compact or diffuse nidus with aneurysms (20-40%)
- Heterogeneous T1/T2 signal due to blood products
- T2 hyperintensity in the cord due to edema, gliosis, ischemia
- Subarachnoid hemorrhage, compression, vascular steal
  - Myelopathy (acute/progressive), pain

SELECTED REFERENCES

1. Leypold BG et al: The early evolution of spinal cord lesions on MR imaging following traumatic spinal cord injury. AJNR Am J Neuroradiol. 29(5):1012-6, 2008

2. Gültasli NZ et al: MRI findings of intramedullary spinal cryptococcoma. Diagn Interv Radiol. 13(2):64-7, 2007

3. Spetzler RF et al: Modified classification of spinal cord vascular lesions. J Neurosurg. 96(2 Suppl):145-56, 2002

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