appropriate imaging for low back pain

Appropriate imaging for back pain

Dr David Lisle

Brisbane Private Imaging Royal Brisbane Hospital University of Queensland


•  Imaging modalities •  Clinical presentations •  Guidelines


•  Imaging modalities – Radiographs (X-rays) – Scintigraphy (bone scan) – CT – MRI

•  Clinical presentations •  Guidelines

Radiographs

What you see

•  Bony anatomy and alignment

•  Disc height

Radiographs

What you see


•  Disc height

Disadvantages •  Radiation •  Nonspecific

–  OA changes in most adults

•  Insensitive –  No direct visualisation

of neural and other nonbony structures

Bone scan

What you see

•  Bone pathology –  Osteoblastic activity

Bone scan

What you see

•  Bone pathology –  Osteoblastic activity

Disadvantages

•  Radiation •  Very nonspecific •  Relatively poor

anatomical resolution –  (Improved with

SPECT; SPECT/CT) –  No direct visualisation

of neural and other nonbony structures

CT

What you see


•  Cross sectional view of spinal canal and foramina

•  Disc, thecal sac, nerve roots

CT

What you see


•  Cross sectional view of spinal canal and foramina

•  Disc, thecal sac, nerve roots

Disadvantages

•  Radiation •  Nonspecific

–  Most adults have ‘findings’

•  Poor visualisation of individual neural structures and disc anatomy

Radiation doses

Imaging test Effective dose (mSv)

CXRs Background exposure

Flying hours

CXR 0.02 1 3 days 4

Lumbar X-ray 1.5 75 6/12 300

Lumbar CT 2-10 100-500 8/12 - 3 years 400 - 1800

Bone scan 6 300 2 years 1200

MRI What you see


•  Bone pathology •  Multiplanar view of

spinal canal and foramina

•  Disc: hydration and structure

•  Neural structures: cord, nerve roots

MRI What you see


•  Bone pathology •  Multiplanar view of

spinal canal and foramina

•  Disc: hydration and structure

•  Neural structures: cord, nerve roots

Disadvantages

•  Availability, cost •  Pacemakers,

claustrophobia •  Nonspecific (too

sensitive) –  Most adults have

‘findings’


•  Imaging modalities •  Clinical presentations: classification into 3

broad categories 1.  Nonspecific low back pain 2.  Back pain associated with radiculopathy 3.  Back pain associated with a specific

cause requiring prompt evaluation •  Guidelines

Back pain categories

1.  Nonspecific (mechanical) low back pain –  Acute: < 12 weeks –  Chronic: > 12 weeks –  Ligament/ muscle strain/ tear –  Intervertebral disc degeneration –  Osteoarthritis

–  Facet joints –  SI joints

–  Spondylolysis/ spondylolisthesis


2.  Back pain associated with radiculopathy a)  Unilateral acute nerve root compression

(sciatica) –  Leg pain >> back pain –  Disc herniation

b)  Unilateral chronic nerve root compression –  Disc herniation or spinal stenosis

c)  Bilateral chronic nerve root compression –  Spinal stenosis –  DD vascular claudication

d)  Bilateral acute nerve root compression = ‘cauda equina syndrome’

Cauda equina syndrome

•  Bilateral acute nerve root compression – Massive disc protrusion/ sequestration

•  Sudden onset bilateral leg pain •  Saddle anaesthesia •  Rapidly progressive or severe neurological

deficits – Motor deficits at >1 level – Faecal incontinence – Urinary retention


3.  Back pain associated with a specific cause requiring prompt evaluation −  Cauda equina syndrome −  Cancer −  Vertebral infection −  Vertebral compression fracture −  Ankylosing spondylitis


3.  Back pain associated with a specific cause requiring prompt evaluation −  Cauda equina syndrome −  Clinical scenario

−  Cancer −  Vertebral infection −  Vertebral compression fracture −  Ankylosing spondylitis


3.  Back pain associated with a specific cause requiring prompt evaluation −  Cancer −  Hx of Ca + new onset LBP −  Unexplained weight loss +/-

persistent symptoms +/- age > 50 −  Vertebral infection −  Vertebral compression fracture −  Ankylosing spondylitis


3.  Back pain associated with a specific cause requiring prompt evaluation −  Vertebral infection −  Fever −  iv drug use −  Recent infection

−  Vertebral compression fracture −  Ankylosing spondylitis


3.  Back pain associated with a specific cause requiring prompt evaluation −  Vertebral compression fracture −  Hx of osteoporosis −  Steroid use −  Old age +/- minor trauma

−  Ankylosing spondylitis


3.  Back pain associated with a specific cause requiring prompt evaluation −  Ankylosing spondylitis (seronegative

SpA) −  Nonmechanical, inflammatory type of

back pain: morning stiffness; improved with exercise

−  Alternating buttock pain −  Waking at night −  Younger age


•  Imaging modalities •  Clinical presentations •  Guidelines

– Multiple: different countries and associations

– Common theme: • Triage into 3 broad categories as

described

LOW BACK PAIN GUIDELINES

Diagnostic triage

1. Non-specific LBP 2. Radiculopathy 3. Specific LBP

•  ‘Red flags’

‘Red Flags’ •  Cauda equina syndrome •  Known 10 tumour •  Weight loss •  Severe symptoms, not

settling •  Fever •  Recent infection or Sx •  Osteoporosis •  Steroid use •  Non-mechanical pain •  Child*

Back pain in children and adolescents

Presentation Associated Sx DD Ix

Night pain Fever, malaise Tumour, infection X-ray MRI

Acute pain Radiculopathy +ve SLR

Disc herniation Spondylosis

X-ray MRI

Chronic pain Rigid kyphosis Morning stiffness

“Scheuermann’s” Inflammatory arthropathy

X-ray

Pain with extension Sport: eg rowing

Hamstring tightness Spondylolysis ‘Stress reaction’

X-ray MRI

Pain + recent onset scoliosis

Fever, malaise, +ve SLR

Idiopathic scoliosis Tumour, infection, syrinx, disc herniation

X-ray MRI

Am Fam Phys 2007;76:1669-76

LOW BACK PAIN GUIDELINES •  American College of Physicians & American

Pain Society Recommendations 1. Focused Hx and examination to place patients

into 1 of 3 categories 2. No imaging for nonspecific LBP 3. Imaging for LBP + severe or progressive

neurological deficits OR risk factors for specific cause

4. Imaging for LBP and radiculopathy if candidates for surgery or epidural injection

Ann Intern Med 2007;147:478-491

Diagnostic work-up

Possible cause Imaging Additional studies Nonspecific LBP None None Radiculopathy MRI (CT) Cauda equina MRI Cancer MRI for known 10; X-ray

for other eg wt loss ESR

Vertebral infection MRI ESR, CRP Vertebral compression # X-ray Ankylosing spondylitis X-ray, incl pelvis (MRI) HLA-B27; ESR, CRP

Ann Intern Med 2007;147:478-491

www.imagingpathways.health.wa.gov.au

National Institute for Clinical Excellence (NICE) UK ACR Appropriateness Criteria

Ineffectiveness of imaging for nonspecific LBP

•  Favourable natural Hx – Most improve by 4 weeks; unaffected by imaging

•  Nonspecificity: loose association between findings and symptoms –  ‘Abnormalities’ or normal aging?

•  Potential harms: – Radiation –  ‘Labelling’ –  Incidental findings

Ann Intern Med 2011;154:181-190

•  85 year old female •  Severe acute on chronic mechanical

back pain – Can’t sleep – Limited walking to only a few steps

•  Spontaneous onset •  No known trauma

Radiograph (X-ray)

24/3/2012

24/3/2012 16/12/2011

MRI: pre-vertebroplasty

STIR

2

3

2

3

T1 STIR

•  68M •  Sudden onset bilateral leg pain and

weakness •  Urinary retention

MRI

•  Dx: Cauda equina syndrome •  Cause: massive sequestration •  Other causes:

– Tumour •  Primary of lower cord, nerve, dura, vertebral

body •  Secondary

– Trauma

Cauda equina syndrome

30M 60F 70M

T2

•  62 year old male •  Severe low back pain of rapid onset •  Febrile and unwell •  4 weeks ago underwent abdominal

surgery for perforated diverticulitis

MRI

T2 T1 T1FS con

T2 T1FS con

Thank you

appropriate imaging for low back pain

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