Sequence
Medic
- Good for cord lesions/cord oedema, therefore not used in the lumbar spine.
- Is a gradient sequence therefore overestimates foraminal narrowing.
- Often poor in the thoracic spine, very prone to artefact.
Axial T2 TSE
- Great for assessing canal diameter
- Looking at disc induced compression in foramina and laterally.
- Poor for cord lesions.
- Still best option on the thoracic spine often.
Short tau inversion recovery (STIR)
Sag space sequence
- Volumetric – like a CT
- Can be MPR’d
- Negates need for axial imaging.
- Takes slightly longer to acquire than a Sag T2 TSE.
- In future may obviate the need for contrast in post-discectomy patients.
- Useful abbreviated sequence (this sequence only) if purpose of scan simply to update imaging prior to surgery.
Contrast sequences
- T1 weighted in the spine.
- With or without fat saturation
- Cord tumours - do not fat saturate.
- Won’t see much else enhancement-wise out-with the cord.
- Anything else out-with the cord where there may be surrounding fat, then Fat saturate.
- Can be very artefactual, cauda equina nerve roots almost always appear bright. Many people don’t like them.
Others
- In- and out of phase - usually for problem solving fat poor haemangiomas.
- Diffusion
- In theory good for cord infarcts? Rarely useful in practice.
- Excellent for IDEMS especially for screening study.
- TRICKS or TWIST - time resolved contrast enhanced spinal angiogram
Haemangioma
- CT
- Axial CT will show a “polka-dotted” or "salt and pepper" appearance due to the thickened vertebral trabeculae. On sagittal CT, vertebral haemangiomas typically show the "corduroy" sign due to thicker or denser vertical trabeculae.
- MRI
- MRI shows extraosseous components better and depicts the haemangioma components as fat and water. Thickened trabeculae appear as low signal areas in both T1 and T2 images.
- T1
- Typical: lipid-rich will demonstrate high signal
- Aypical: lipid-poor will demonstrate low signal
- T2: bright/high-intensity signal, usually greater than on T1, due to its high water content
- T1 C+: significant enhancement is seen due to high vascularity
Spinal cord metastases
- Lesions are usually well-defined and typically produce cord expansion over several segments. In contrast to primary intramedullary neoplasms, associated cysts are rare and some patterns of enhancement have been described as helpful in suggesting the diagnosis (see rim sign and flame sign below). Typical MRI signal characteristics are
- T1: hypointense
- T2
- Hyperintense
- Prominent oedema commonly surrounds the tumour nodule
- T1 C+ (Gd)
- Avid enhancement (seen in >80% of cases)
- Peripheral thin region of increased enhancement (rim sign)
- Rim sign diff it from astrocytoma
- Ill-defined enhancement extending above and/or below the lesion (flame sign)
Vertebral metastases
- MRI is sensitive to metastatic disease and is able also to assess for cord compression. The signal intensity of the metastatic deposits will vary according to the degree of mineralisation.
- Osteoblastic metastases
- T1: hypointense
- T2: hypointense
- Mixed sclerotic and lytic extradural bone lesions
- T1: hypointense
- T2: hypo- and/or hyperintense
- Lytic extradural bone lesions
- T1: intermediate to hypointense
- T2: hyper- or isointense
- T1 C+ (Gd): enhancement usually present
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Notochordal remnant tumour
- CT
- Vertebral body sclerosis
- Can extend to the cortex or involve the entire vertebra
- Preserved trabeculae
- No cortical destruction
- MRI
- Well-defined osseous lesions
- T1: hypo- or isointense; may demonstrate hyperintense intra-lesional punctiform foci representing fat lobules due to entrapped bone marrow
- T2: hyperintense
- T1 C+ (Gd): usually no enhancement (in around 75% of cases)
- DWI/ADC: no restricted diffusion
- No soft tissue component
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Fatty Marrow Reconversion
- Signal intensity will be that of normal red marrow being low T1 signal but still higher than skeletal muscle.
- In the appendicular skeleton, it tends to be symmetrical and homogeneous, whereas in the axial skeletal it can be heterogeneous/multifocal.
- Marrow reconversion occurs in the reverse order or normal red to yellow marrow conversion.
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Multiple myeloma
- Most frequently used MR sequences for the evaluation of bone marrow are conventional T1 spin-echo and T2 spin-echo sequences.
- T1
- Typically low signal
- High-grade, diffuse involvement may become isointense to adjacent normal marrow
- T2 high signal
- T1 C+ (Gd)
- Hyperintense
- DWI/ADC: Lesions usually exhibit restricted diffusion, with higher signal on high b-value DWI compared to the very low signal of normal background marrow.
- Most mets do not restrict
not sure if I tagged this image correctly
Fibrous dysplasia
- Has fluid levels in cyst
Pagets
- Diffuse sclerosis throughout the whole bone
- Picture framing of the vertebral body
Epedneyoma
- Haemorrhagic capping
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