Spinal Epidural Space:
Anatomy, Normal variations, and Pathological Lesions
on MR Imaging

Chhabra A, MD¹; Batra K, MD¹; Satti S, MD¹; Patel S, MMS¹; Feitell S, MMS¹; Gonzales C, MD¹; Faerber E, MD²; Koenigsberg RA, DO FAOCR¹

¹Drexel University College of Medicine, Philadelphia, PA
² St Christopher Hospital for Children, Philadelphia, PA

Tumors

Age (yrs)
Sex [Female(F), Male (M)]

Most common location in spine

Most common location in  the vertebra

T1W MRI signal

T2W MRI signal

Contrast MRI enhancement (Enh)

Associated findings on MRI

Helpful other imaging findings

Arachnoid Cyst
(Fig- 20a,b)

None

Lower thoracic

Intradural > Posterior ES

CSF signal

CSF signal

None

Cap sign present.
CSF signal on PDWI / FLAIR scans.

Delayed post myelo CT-Fills with CSF.

Angiolipoma

40-60, F>M

Thoracic

Posterior ES

Hyper

Hyper-Iso

Enh (fat-sat T1WI)

Increased vascularity- isointense on T1WI.

Enh excludes lipoma and lipomatosis.

Epidural Hemangioma

40-60, F>M

Thoracic

Posterior ES

Iso

Iso-Hypo

Avid Enh

Heterog enh - thrombo-sis & degeneration.

None.

Hemangioma
Aggressive    Hemangioma

40-60, F>M
(Fig- 21a-c)

Dorsolumbar

Thoracic

Body

Body

Hyper

Hypo

Hyper

Hyper

Avid Enh

Avid Enh

Spinal cord compres-sion with aggressive hemangiomas.

Axial CT- Polka dot sign Heavily T2W- Light bulb sign.

ABC
(Fig- 22,23)

10-20, F>M

Dorsolumbar

Neural Arch

Cystic+/- Solid

Cystic+/- Solid

Enh- rim, septae & solid areas.

Fluid-Fluid levels
Hypointense rim.

Balloon like bony expansion, contigous vertebrae involved.

GCT

30-50, F>M

Sacrum> Spine

Body

Hypo-Iso

Iso-Hyper

Heterogen Enh

Fluid-Fluid levels- with co-existent ABC.

Xray - Soap bubble matrix. No sclerosis.

Perineural Cyst
(Fig- 24a,b)

30-40,
M=F

Sacrum, Lumbar

Sacral canal, Neural foramen.

CSF signal

CSF signal

None

Flow sensitive scan- Loss of signal in cyst.

Wide canal / neural foramen. Fills in post myeloCT.

Neurofibroma

 (Fig- 25a-c)

20-30, M=F

Cervical

Intradural >
Epidural

Iso

Iso-Hyper

Homogen Enh

Target sign on T2WI.

13-65% of NF1 have spinal NF.

Plasmacytoma

 (Fig- 26a-d)

50-60, M>F

None

Body

Iso-Hypo

Iso-Hyper

Heterogen Enh

Mini Brain appearance-T1WI. Curvilinear signal voids on T1 & T2WI.

Extensive paraspinal and epidural mass. Involve of IV disc.

Lymphoma
 (Fig- 27a,b)

40-70, M>F

Thoracic

Body with epidural extension

Iso

Varies

Avid Homogen Enh

Can be isolated epid-ural or leptomening-eal or intramedullary.

CT- Ivory vertebra, multi-segmental involvement in spine.

Metastasis

 (Fig- 28a-c)

None

None

Pedicles

Varies

Varies

Hetrogen
Enh

Intervertebral disc spared.

Known primary malignancy.

Ewing Sarcoma
 (Fig- 29a-c)

10-20, M>F

Sacrum> spine

Body
Vertebra Plana

Hypo

Iso-Hyper

Hetrogen
Enh

Permeative bone destruction/ Intact cortex.

Extensive soft tissue component may be present.

Osteosarcoma

(OS) (Fig- 30a-c)

40-50 ,
M>F

None

Neural arch

Hypo

Hypo

Hetrogen
Enh

Fluid-Fluid level in Telangectatic OS.

Bone matrix on Xray/ CT scan.

Chondrosarcoma (CS) (Fig- 31a-c)

40-60, M>F

None

None

Hypo

Varies

Enh in rim & septations.

Ring and arc pattern of enhancement.

Contigous multiple neural arch involve.

Fig. 20-ab.
Axial and Sagital T2W scans in a 42 year old woman demonstrate a cystic lesion of CSF intensity in the left postero-lateral epidural space causing scalloping of the posterior sacrum and displacement of the thecal sac to the right side consistent with a arachnoid cyst.

Fig. 21-ac.
Sagital T1W and T2W and Axial CT scans in a 25 year old boy demonstrate a soft tissue mass replacing a middorsal vartebral body appearing hypo-isointense on T1W and markedly hyperintense on T2W images with epidural extension. Note the Polka dot appearance on CT scan image (right) consistent with a hemangioma.

Fig. 22 a-d.
Axial T1W, Coronal CT, Sagital DSA and open mouth plain X-ray projections demonstrate an expansile isointense mass replacing the left anterior arch of the C1 vertebra. The DSA image (bottom Left) after selective catheterization of the left vertebral artery demonstrates pooling of the contrast in the cystic mass (red arrow). Plain X-ray correlation (bottom right) redemonstrates the absence of the anterior arch in the C1 vertebra (Yellow arrow). The lesion was proven to be a ABC.

Fig. 23 a-d
Axial CT scan, Axial T1W (Top) and Axial T2W and Sagital T2W (bottom) scans in a 13 year old girl with back pain demonstrate an expansile mass involving the body and left posterior elements of the lumbar vertebra with epidural extension and multiple fluid-fluid levels consistent with an ABC.

Fig. 24-ab.
Axial T1W and T2W scans in a 72 year old woman demonstrate a cystic lesion of CSF intensity (arrow) adjacent to the traversing nerve root in the left neural foramen at T8 level consistent with a preineural cyst.

Fig. 25-ac.
Axial T1W, Coronal STIR and Sagital post contrast T1W scans in a 54 year old woman with back pain demonstrate a dumbbell shaped enhancing intradural extramedullary mass (arrow) appearing isointense on T1W and hyperintense on T2W images. The mass extends in the epidural space of the left neural canal at L5-S1 level and was confirmed to be a neurofibroma.

Fig. 26-a-c.
Sagital T2W & post contrast T1W scans (Top) demonstrate a iso-hyperintense mass involving a lower dorsal Vertebra in a 55 year old man. DSA images before and after embolization (bottom) demonstrate successful treatment. The mass was proven to be a plasmacytoma on percutaneous biopsy

Fig. 27-ab
Axial T1W and STIR scans in a 52 year old man demonstrate extensive lymphoma deposits in the whole spine, appearing isointense on T1W and iso-hyperintense on T2W images. Note the epidural extension (arrow).

Fig. 28-ac.
agital T1W scan and post lumbar Myelogram images in frontal and lateral positions in a 60 year old man with history of lung cancer demonstrate metastatic epidural deposit causing abrupt cut-off of the contrast column at L4-5 level.

Fig. 29-ac.
Sagital T1W & T2W and Axial post contrast T1W scans in a 18 year old boy with back pain and fever demon- strate vertebra plana at T9 level due to Ewing’s sarcoma. Also note the enhancing pre & paravertebral and epidural soft tissue mass (arrow) appearing hypo-intense on T1W scans and iso-hyperintense on T2W scans causing marked compression of the dorsal cord.

Fig. 30-ac.
Post contrast Sagital & Axial T1W scans in a 26 year old boy with enhancing mass involving the posterior elements of the T12 vertebra. The lesion was found to be an osteosarcoma. Note the associated marked epidural (arrow) and paraspinal soft tissue component.

Fig. 31-ac.
Post contrast T1W (Right) scans in a 72 year old woman demonstrate a large multilobulated mass with rings and arc enhancement appearing hypointense on T1W and hyperintense on T2W scans involving the lower dorsal vertebra and its posterior elements. The lesion was found to be chondrosarcoma on surgery. Note the post-corpectomy changes in the vertebra.