MRI of the Spine Jennifer Jones Radiology Manager Bristol Nuffield

Transcription

1 MRI of the Spine Jennifer Jones Radiology Manager Bristol Nuffield

2 COILS Used to improve the diagnostic quality of scan images. Used in conjunction with the main bore of the magnet All scanners have different sets of coils for Imaging different body parts eg spine or head coil Body part to be examined Is placed within the coil or lies on top of the coil depending on the area under examination.

3 Patient orientation Does the examination allow for a change of orientation? Area to be scanned will always be at the centre of the bore of the magnet. Always feet first : Brain, Spine, Pelvis, Knees, ankle foot Always head first : Shoulder, Wrist dependent on patient

4 Tissue Contrast We generate contrast in the images by using an appropriate pulse sequence changing timing parameters. These make differences in energy exchange by the desired process predominate, we then minimise contributions from the other process(es) &/or chemicals T1w T2w Fat Suppression Water Suppression 4

5 Image (Tissue) Contrast We are not just stuck with information about how much hydrogen there is in each tissue, but also how easily each tissue can lose the extra energy we put in (and by which process) Radiographer can choose via manipulation of scan parameters which effects predominate on the image, hence we choose type of image contrast we want (image weighting) This makes MRI very useful, but quite hard to interpret - you need to know how each tissue should behave 5

6 T1 T1 & T2 T2 Some tissues (always) give the same signal regardless of weighting:- Cortical bone black Healthy Ligament black Healthy Tendon black Fat white (unless suppressed) 6

7 What are sequences? Pulse Sequences are the scans themselves Different types of pulse sequences are used to produce images which demonstrate different things Spin Echo T1, T2, PD Gradient Echo T1, T2, PD Fast Spin Echo T1, T2, PD STIR Fat Suppression FLAIR Fluid Suppression 7

8 Structures on T1,T2, FATSAT, STIR, FLAIR Fat Bright on T1, Bright on T2 Fluid Dark on T1, Bright on T2 Fluid No signal on FLAIR due to Inversion technique Fat No signal on FATSAT techniques (Chemical Sat technique) Fat No signal on STIR due to Inversion technique

9 T2 Fast Spin Echo Sagittal Demonstrates contrast between disc/osteophyte and the bright signal of CSF. Tumour, syrinx or plaque within cord will show high signal and contrast with normal tissue of the cord.

10 T1 Spin Echo/Fast Spin Echo Sagittal Anatomical overview of the spine. Can confirm a plaque or syrinx Additional info re pathology differing signal characteristics Same location as the Sag T2 so tissue characteristics can be compared with T2 series information? Fast Spin Echo/Spin Echo

11 Scan Sequences C.SPINE T2 SAGITTAL T1 SAGITTAL T2 AXIAL GE

12 T2 Sagittal C.SPINE Demonstrates contrast between disk/osteophyte and the bright signal of CSF Tumour, syrinx or plaque within cord with show high signal and contrast with normal tissue of the cord

13 T1 SAGITTAL C.SPINE Anatomical overview of the spine. Demonstrates any cord enlargement. Can confirm a plaque or syrinx Same slice position as the Sag T2 so tissue characteristics can be compared to T2 series.

14 Ax T2 Gradient Echo C.SPINE Axial plane to demonstrate any lateral lesions and the exiting nerve roots T2* weighting produces bright signal from CSF to contrast against any lesion FSE not used in Axial plane susceptible to flow artefacts generated on this pulse sequence (Only when metal fusion)

15 Anatomy Sagittal T2-weighted image, cervical spine. 1 Clivus 2 Atlanto-occipital ligament 3 Anterior longitudinal ligament 4 Anterior arch C1 5 Superior fascicle of cruciform ligament/tectorial membrane 6 Apical ligament 7 Transverse ligament (of cruciform ligament) 8 Posterior arch C1 9 Posterior occipital atlantal membrane 10 Nuchal ligament 11 Semispinalis capitis muscle 12 Cervical spinal cord 13 Posterior longitudinal ligament/anterior thecal sac Dura 14 Posterior dural sac 15 Interspinous ligament 16 Gray matter along central canal 17 Supraspinous ligament 18,Ligamentum flavum 19 Dental synchondrosis

16 Thoracic Spine T2 SAG T1 SAG T

17 Axial T2 FSE

18 LUMBAR SPINE T2 SAG T1 SAG

19 Normal Lumbar Spine Disc hydration Normal lumbar curvature Plenty of CSF and spinal space Uniform signal from bone marrow of vertebra Visible cord and equina (T12/L1)

20 Axial T2 Lumbar Spine View cauda equina nerve roots Kidneys at L2 level Aorta and IVC Facet joints Thecal sac Psoas muscles

21 Pathology for Lumbar Spine? Disc bulge Protrusion/extrusion Sequestered disc? Stenosis? Discitis Burst fracture Back/leg pain Sciatica? Cause Incontinence/bowel problems? Metastasis? Tumour? TB involvement Cauda equina syndrome

22 MRI - Degenerative Disc Disease Did you know? Age: % 98% 85-95%

23 MRI Herniated Disc Levels Did you know? L4-L5, L5-S1 L3-L4 L2-L3 2-3% L1-L2, T12-L % 5-8% 1%

24 Disc Disease -terminology Disc bulge -Annular fibres intact Disc protrusion -Localized bulging with damage of some annular fibres Disc extrusion -Extended bulge with loss of annular fibres, but disc remains intact Disc sequestration -Fragment of disc broken off from the nucleus pulposus, can move within the extra dural area

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