Intradural/Extramedullary Lesion, T1 Hypo, T2 Hypo

Jeffrey S. Ross, MD

DIFFERENTIAL DIAGNOSIS

Common

Less Common

ESSENTIAL INFORMATION

Helpful Clues for Common Diagnoses

CSF Flow Artifact
- Related to both time-of-flight (TOF) effects and turbulent flow
  - Turbulent flow ⇒ more rapid dephasing with signal loss
  - TOF signal loss seen with SE or FSE when protons do not experience both initial RF pulse and subsequent refocusing pulse
  - Increased signal loss with higher flow velocity, thin slices, longer TE, imaging perpendicular to flow
  - Gradient echo imaging less susceptible to CSF flow artifacts
- Repeat study with different imaging plane, GE sequences with short TE
Post-Operative Change, Normal
- Most common will be small foci of gas from violation of dura
Metal Artifact
- Fast spin echo better than conventional spin echo better than gradient echo
- Use larger field of view
- Appropriate geometric orientation of frequency encode direction
  - Parallel to pedicle screws
Vascular Malformation
- Most common is type 1 dural fistula
- Hallmark is T2 hyperintense cord (usually distal thoracic), intradural flow voids (especially dorsal)
Meningioma, Calcified
- Well-defined ID/EM lesion with dural base
- Generally low T2 signal
- Solitary lesion, except with NF2

Helpful Clues for Less Common Diagnoses

Ependymoma, Myxopapillary (Calcified)
- Well-defined enhancing cauda equina mass with evidence of prior hemorrhage
Arachnoiditis Ossificans
- Intradural ossification associated with post-inflammatory adhesion and clumping of lumbar nerve roots
- Low signal thickened dura and roots
Superficial Siderosis
- SAH (multiple etiologies) causing hemosiderin deposition on cord, nerve surface
- Diffuse hypointensity of cord surface on T2WI, GE