Post operative Spinal Imaging- A multimodality approach

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1 Post operative Spinal Imaging- A multimodality approach UKRC June 2014 Dr Sajid Butt Consultant Radiology, RNOH

2 Summary Common Spinal Surgeries Image Optimisation Spinal Instrumentation Clinical Scenarios

3 Common Spinal Surgeries Discectomy: Fenestration,Laminectomy, Facetectomy, ACD Foraminotomy Instrumented Fusion: ACDF, PLF, PLIF, TLIF, ALIF, XLIF Deformity Correction Tumour Surgery: Corpectomy, Vertebrectomy

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5 Common Spinal Surgeries Discectomy: Fenestration,Laminectomy, Facetectomy, ACD Foraminotomy Instrumented Fusion: ACDF, PLF, PLIF, TLIF, ALIF, XLIF Deformity Correction Tumour Surgery: Corpectomy, Vertebrectomy

6 ACDF

7 C5-C6 ACDF & Plate C5 Corpectomy & Plate Clin Rad 68 (2013) 64-74

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10 Decompression and C2-T1 lateral mass fixation rod and screw construct

11 Laminoplasty

12 Lumbar Fusion Indications Instability (spondylolisthesis) Deformity (degenerative scoliosis) Recurrent radiculopathy Discogenic low back pain Disk replacement as alternative

13 Lumbar Interbody Fusion Posterior (PLF and PLIF) Transforaminal (TLIF) Anterior (ALIF) Extreme lateral (XLIF) Clin Rad 68 (2013) 64-74

14 L4-L5 PLIF

15 TLIF

16 L5-S1 ALIF Transperitoneal approach Best L5-S1 exposure

17 XLIF Retroperitoneal / Transpsoas Blunt dissection EMG to help avoid plexus Renal / other visceral / lumbar plexus injury Clin Rad 68 (2013) The Spine Journal 2006; 6:

18 Deformity Correction Coronal (scoliosis) Sagittal (kyphosis) Complex decision making Non-surgical options

19 AIS

20 Marfan s Syndrome Two Stage Fusion

21 Image Optimisation CT is best suited to evaluate metalwork placement and to assess for fusion MR is good at assessing spinal canal, post operative haematoma, possible infection and assessment of nerves Both modalities suffer from susceptibility to generate artefacts Both are used to get the maximum information

22 Image Optimisation MR 1. T1, T2, T2 FS 2. Post gadolinium 3. Metallic artefacts management: Alignment along external magnetic field Frequency encoding axis along metalwork Increase bandwidth Use STIR and avoid gradient echo

23 Metallic artefact management MR Bandwidth Echotrain length Voxel Size Frequency encoding direction Managing susceptibility Increase Increase Decrease Parallel to long axis of metal Magnetic field Direction of magnetic field Fat suppression Decrease Alignment along the screws- Upright scanner STIR in place of radiofrequency selective FS Chemical shift imaging

24 T1 SE PD FSE T2 FSE

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26 Effect of Increasing BW, ETL and Decreasing Voxel Neuroimaging Clinics of North Am, 24 (2):349-64

27 Image Optimisation CT: 1. Increase KvP- 110 KeV is most suited 2. Reduce mas to control dose 3. Reduced slice thickness 4. Iterative reconstruction 5. Dual energy CT scan 6. Consider CT myelogram Increasing KvP 15% Reduce mas 50% Low contrast detectability is affected by increasing KvP

28 Neuroimaging Clinics of North Am, 24 (2):349-64

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36 Imaging Post-Operative Positioning Intra-operative injury Early & Late Complications Post discectomy complications Implant failure / migration / loosening Periprosthetic Fracture Infection

37 Post Discectomy Persistent or recurrent symptoms MR to differentiate between post operative scar and disc IV gadolinium helps Some patients will show no significant abnormality

38 Post Discectomy- Normal findings Early Stage 0-6 months Annular fissure Modic type 1 change (in up to 18%) Disc space enhancement Disc height loss (look for new foraminal compression) Perineural soft tissue swelling

39 Post Discectomy- Normal findings Nerve root enhancement Not after 6 months Facet joint enhancement Shrinkage of spinal canal- recovers within a month Thickening of nerve roots of cauda equine Post operative haematoma and muscular oedema

40 Post Discectomy Complications Recurrent disc prolapse Symptomatic scar Infection Wrong level surgery Arachnoiditis Post operative haematoma

41 Infection MRI may be normal! Fluid in disc, endplate changes, diffuse disc and endplate enhancement and paravertebral abscess Degenerate disc is low on T2 and may show only a linear pattern of enhancement Biopsy and clinical correlation

42 68 years old male- Discectomy L3-4 4 weeks ago

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45 Disc Vs Scar IV gadolinium Image within 3-5 minutes of IV injection Scar enhances early Disc has well defined margins and shows no enhancement Swelling of nerves is of doubtful value Prominent scar is also linked with poorer outcome

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48 L4-5

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50 Post Discectomy Complications Arachnoiditis- 3% after discectomy 3 patterns Difficult to treat Pseudomeningocoele- Rare. Symptoms after asymptomatic interval of several weeks

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54 Malpositioning

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56 T10 T 12

57 L2 L3

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59 Intra-Operative Injury Dural Tear / Pseudomeningocoele

60 Implant Failure

61 Implant Failure

62 Implant failure / Pseudoarthrosis

63 Implant Failure / Pseudoarthrosis

64 Disc Cage Non-Union

65 Disc Cage Non-Union

66 Implant Migration

67 Adjacent Segment Abnormality

68 Day 1 Post Op

69 Day 14 post Op Case courtesy Dr R Hughes NOT HIS CASE

70 Summary Understanding surgical technique and philosophy Answering the clinical question Use all modalities in a timely fashion Use of IV gadolinium and CT myelogram Comparison with previous films and careful follow up

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