MR Myelography¶
Definition¶
MR myelography is a non-invasive MRI technique that produces images resembling conventional myelography by using heavily T2-weighted sequences to highlight CSF as very bright signal against a dark background. It provides a "CSF map" of the spinal canal without intrathecal contrast injection.
Technique¶
Sequences¶
- Heavily T2-weighted sequences with very long TE (>200 ms) — CSF appears very bright; all other tissues are suppressed to near-black
- 3D CISS (Constructive Interference in Steady State) or 3D FIESTA — thin-section volumetric sequences that provide high-resolution images of the CSF-filled spaces
- Single-shot fast spin echo (SSFSE) / HASTE — rapid thick-slab acquisitions that produce "myelogram-like" projection images
Acquisition¶
- Can be performed in sagittal and coronal planes
- Thick-slab (40–60 mm) images produce projection views similar to conventional myelograms
- Thin-section volumetric 3D acquisitions allow multiplanar reformats and detailed evaluation of individual nerve roots
- No contrast injection required — entirely non-invasive
Indications¶
- Evaluation of nerve root compression — particularly useful for visualizing individual nerve rootlets and their relationship to compressive pathology
- Intradural lesions — schwannomas, meningiomas, and drop metastases are silhouetted against bright CSF
- CSF flow abnormalities — Chiari malformation, arachnoid webs, arachnoiditis
- Myelographic effect for patients who cannot undergo conventional myelography
- Arachnoiditis — clumping of nerve roots within the thecal sac
- Complementary to standard MRI sequences — adds diagnostic value without contrast
Imaging Findings¶
| Finding | Appearance |
|---|---|
| Normal | Bright CSF column with dark nerve roots visible as linear filling defects |
| Disc herniation | Indentation of the bright CSF column by the disc; nerve root displacement |
| Stenosis | Narrowing or complete interruption of the CSF column |
| Intradural tumor | Dark filling defect within the bright CSF, with meniscus sign |
| Arachnoiditis | Clumped, irregular nerve roots; "empty sac" sign (roots adherent to periphery) |
| Nerve root avulsion | Pseudomeningocele — CSF extension beyond the expected root sleeve margin |
Clinical Pearl
MR myelography is particularly useful for evaluating brachial plexus avulsion injuries — traumatic pseudomeningoceles appear as CSF-bright outpouchings extending beyond the neural foramen along the expected course of the avulsed nerve root. This finding indicates root avulsion at or proximal to the dorsal root ganglion, which has a poor prognosis for spontaneous recovery.
Advantages Over Conventional Myelography¶
- Non-invasive — no lumbar puncture, no intrathecal contrast
- No radiation exposure
- No risk of post-lumbar puncture headache
- Can be added to a standard MRI protocol without additional patient preparation
Limitations¶
- Cannot demonstrate dynamic CSF flow as well as phase-contrast MRI or real-time fluoroscopic myelography
- Spatial resolution may be lower than CT myelography for fine detail
- Cannot evaluate the epidural space or bony structures (complementary CT or standard MRI sequences needed)
- Image quality depends on CSF pulsation artifacts
Key Points¶
- MR myelography uses heavily T2-weighted sequences to create myelogram-like images non-invasively
- CSF appears very bright; nerve roots and pathology appear as dark filling defects
- Useful for nerve root evaluation, intradural lesions, arachnoiditis, and brachial plexus avulsion
- No contrast injection, no radiation, no lumbar puncture
- Complementary to standard MRI sequences — adds diagnostic value without additional risk
References¶
- el Gammal T, Brooks BS, Freedy RM, Crews CE. MR myelography: imaging findings. AJR Am J Roentgenol. 1995;164(1):173-7. Available from: https://pubmed.ncbi.nlm.nih.gov/7998533/
- el Gammal TA, Crews CE. MR myelography of the cervical spine. RadioGraphics. 1996;16(1):77-88. Available from: https://pubmed.ncbi.nlm.nih.gov/10946691/
- Wang YF, Lirng JF, Fuh JL, Hseu SS, Wang SJ. Heavily T2-weighted MR myelography vs CT myelography in spontaneous intracranial hypotension. Neurology. 2009;73(22):1892-8. Available from: https://pubmed.ncbi.nlm.nih.gov/19949036/
- Kim BR, Lee JW, Lee E, Kang Y, Ahn JM, Kang HS. Utility of heavily T2-weighted MR myelography as the first step in CSF leak detection and the planning of epidural blood patches. J Clin Neurosci. 2020;77:110-115. Available from: https://pubmed.ncbi.nlm.nih.gov/32402615/
- Carvalho GA, Nikkhah G, Matthies C, Penkert G, Samii M. Diagnosis of root avulsions in traumatic brachial plexus injuries: value of computerized tomography myelography and magnetic resonance imaging. J Neurosurg. 1997;86(1):69-76. Available from: https://pubmed.ncbi.nlm.nih.gov/8988084/
- Ozdoba C, Gralla J, Rieke A, Binggeli R, Schroth G. Myelography in the age of MRI: why we do it, and how we do it. Radiol Res Pract. 2011;2011:329017. Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC3197073/
- Myelography. Radiopaedia.org. Available from: https://radiopaedia.org/articles/myelography