Diagnostic Imaging Pathways – Low Back Pain
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This pathway provides guidance for imaging adult patients with acute lower back pain. There are prompts regarding important considerations when planning a referral including ‘red flags’.
Date reviewed: August 2013
Date of next review: 2017/2018
Published: August 2013
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Move the mouse cursor over the PINK text boxes inside the flow chart to bring up a pop up box with salient points.
Clicking on the PINK text box will bring up the full text.
The relative radiation level (RRL) of each imaging investigation is displayed in the pop up box.
| SYMBOL | RRL | EFFECTIVE DOSE RANGE |
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None | 0 |
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Minimal | < 1 millisieverts |
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Low | 1-5 mSv |
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Medium | 5-10 mSv |
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High | >10 mSv |
Images
Image GalleryNote: These images open in a new page | ||
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L4/L5 Disc Herniation Image 1a and 1b (Computed Tomography): Axial and sagittal images demonstrating a large left sided eccentric disc protrusion at L4/L5 that is compressing the traversing left L5 nerve root. |
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| 1c |  |
Image 1c and 1d (Magnetic Resonance Imaging): Axial and sagittal images of the same patient. |
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Teaching Points
Teaching Points
- The prevalence of previously undiagnosed serious pathology in patients presenting with acute low back pain in the primary care setting is very rare 1
- Most patients with acute low back pain have substantial improvements in pain and function within one month 2
- Routine or immediate lumbar spine imaging for low back pain without indications of serious underlying conditions does not affect management or improve clinical outcomes and is associated with radiation exposure and increased expenses 3,4
- 'Red flags' that prompt imaging include recent significant trauma (mild trauma if age = 50), unexplained weight loss, fever, age <22 or >55 years, history of malignancy or immune compromise, intravenous drug use, osteoporosis or glucocorticoid use, suspicion of ankylosing spondylitis and compensation or work injury issues
- If there are no 'red flags', imaging is indicated only after a period of conservative therapy is trialled first 3
- Initial investigation is with plain films
redflags
Red Flags for the Investigation of Acute Low Back Pain
- These features on history and examination may help to increase the yield of lumbar radiography and have been adapted from criteria proposed by various guidelines 5-8
- Constitutional symptoms e.g. fever, night sweats
- Immunosuppression
- Intravenous drug use
- History of malignancy or unexplained weight loss of insidious onset
- Prolonged use of corticosteroids, osteoporosis
- Age <20 or >55 years
- Recent history of violent trauma (or mild trauma if age = 50)
- Presence of associated contusion or abrasion
- Constant progressive, non mechanical pain (no relief with bed rest)
- Thoracic pain
- Structural deformity
- Widespread neurological signs and symptoms (including cauda equina syndrome)
- Failure to improve after 4-6 weeks of conservative low back pain therapy
- There is no convincing evidence that the absence of these red flags is sufficient to exclude serious underlying disease and some red flags have high false positive rates,1,9,10 but they may help to reduce unnecessary use of plain radiography
plainradiograph
Plain Radiograph
- Frequently but often inappropriately used for the investigation of low back pain
- The majority of patients with low back pain have either normal lumbar radiographs or age related degenerative changes that do not necessarily correlate with the presence or severity of pain 8,11,12
- Disc space narrowing is more strongly associated with back pain than other radiographic features 13
- Routine, immediate plain radiographs are of limited diagnostic value and have no benefit to patient function, pain or disability, other than patient satisfaction, which must be weighed against the significant gonadal radiation dose 3,8,14,15
- Plain radiographs are not indicated in patients with low back pain unless there are significant risk factors or ‘red flags’ for serious underlying disease or symptoms have persisted for greater than 6 weeks 3,16,17
mri
Magnetic Resonance Imaging (MRI)
- Advanced imaging modality of choice in evaluation of low back pain
- There is a paucity of evidence for the appropriate timing of MRI, but emergent MRI has been suggested for suspected cord compression, cauda equina syndrome, abscess or infection. It may be appropriate to trial a period of conservative care prior to MRI for patients with radiculopathy 18
- Advantages compared to CT include
- No ionising radiation
- Better soft tissue contrast – modality of choice for detection of spinal infections, metastases, nerve root disorders and disc abnormalities
- Disadvantages compared to CT include 17
- Lower spatial resolution – cortical bone lesions are not as well visualised. Where bony anatomy is critical, CT may be preferred
- Claustrophobia
- Longer scanning time needed
- Contraindicated in the presence of a ferromagnetic substance, e.g. Pacemaker, aneurysm clip, cochlear implant, ocular foreign body, spinal cord stimulator and some stent materials
- Most findings on MRI in patients presenting with low back pain represent progressive age-related changes and are not associated with acute events, although primary radiculopathies may have new root compression findings 19
- MRI is recommended for vertebral inflammatory and infectious processes. It can detect osteomyelitis as early as 3-5 days after onset of infection and is reported to have a sensitivity of 96% and specificity of 92% for the detection of spinal infections, more accurate than plain radiography or bone scan 20,21
- MRI is the most accurate modality for detecting suspected malignancy and vertebral metastasis and determining disease extension around the spinal cord. Where there is a high clinical suspicion MRI should be considered even if bone scintigraphy is negative or equivocal 20-25
- A recent metaanalysis concluded MRI can help distinguish benign from malignant vertebral compression fractures26
- MRI has a high sensitivity (87-96%) and moderate specificity (68-75%) in the detection of spinal stenosis 27
- MRI has a pooled 75% sensitivity (64-92%) and 77% sensitivity (55-100%) for detection of lumbar disc herniation on metaanalysis, and high sensitivity (81%) but lower specificity (52%) in detection of resultant nerve root compression compared to surgical reference standard, not significantly different compared to CT and CT myelography 27,28
- Abnormalities such as disc degeneration, spondylosis, disc herniation, bulging disc and foraminal stenosis can be seen on MRI in asymptomatic individuals and any causal attribution should be made after strict correlation with clinical signs and symptoms 29-31
- The ability to distinguish between extrusions and protrusions, both subtypes of disc herniations, is important. Disc extrusions have a 'neck' and are rare in asymptomatic patients where as protrusions are broad based and commonly occur in asymptomatic people
ComputedTomography
Computed Tomography (CT)
- Advantages of CT over MRI include
- Superior bony detailing of the spine, particularly the facet joints 32 and the posterior elements
- Faster acquisition time and less sensitive to patient movements
- CT is useful for identifying bone structural problems and for post-surgical evaluation of bone graft integrity, surgical fusion and instrumentation 5,33
- CT has a similar accuracy to MRI and CT myelography in identification of lumbar disc herniation. 28 A recent metaanalysis on the detection of lumbar disc herniation reported a pooled 77.4% sensitivity and 73.7% specificity for CT compared to surgical findings 34
- As with other imaging tests, many abnormalities found with CT, including herniated discs are found in asymptomatic people and this reduces the specificity of the test
- There is a paucity of evidence on the accuracy of CT for detection of vertebral metastases, osteomyelitis, compression fractures or ankylosing spondylitis 34
CT Myelography
- CT myelography is an invasive procedure that involves injecting the thecal sac with iodinated contrast material. This allows the nerve root sleeves to be visualised and a lack of filling, displacement, or swelling of a nerve root may indicate adjacent pathology 28,35
- MRI is the preferred first line investigation of suspected radiculopathy or spinal stenosis due to its excellent soft tissue definition and non-invasiveness. Currently, the main diagnostic role of CT myelography is as an alternative method of investigation if MRI is unavailable or contraindicated 28,36
- For detecting a herniated disc, CT myelography has a sensitivity of 73-95% and a specificity of 57-88%. This is similar to that of non-invasive helical CT 28,36
- Limitations
- Invasive procedure.
- Associated small risk of exacerbating the neurological deficit
Lumbar Discography
- Lumbar provocation discography, which includes disc stimulation and morphological evaluation, may distinguish a chronically painful lumbar disc from other potential sources of pain where less invasive studies have been indeterminate 38
- However, careful consideration should be given to the risks of the procedure. A recent study suggested that discography may cause accelerated degenerative changes, disc herniation, loss of disc height and development of reactive end-plate changes in tested discs 39
bonescan
Bone Scan
- Sensitive but not very specific for detecting infection, malignancy or occult fractures. Generally MRI is preferred for localised lower back pain
- Bone scintigraphy is useful in the evaluation of suspected widespread or multifocal osseous infections or metastases, or where MRI is contraindicated or unavailable 17
References
References
Date of literature search: May 2013
The search methodology is available on request. Email
References are graded from Level I to V according to the Oxford Centre for Evidence-Based Medicine, Levels of Evidence. Download the document
- Henschke N, Maher CG, Refshauge KM, Herbert RD, Cumming RG, Bleasel J, et al. Prevalence of and screening for serious spinal pathology in patients presenting to primary care settings with acute low back pain. Arthritis Rheum. 2009;60(10):3072-80. (Level I evidence)
- Pengel LH, Herbert RD, Maher CG, Refshauge KM. Acute low back pain: systematic review of its prognosis. BMJ. 2003;327(7410):323. (Level I evidence)
- Chou R, Fu R, Carrino JA, Deyo RA. Imaging strategies for low-back pain: systematic review and meta-analysis. Lancet. 2009;373(9662):463-72. (Level I evidence)
- Gillan MG, Gilbert FJ, Andrew JE, Grant AM, Wardlaw D, Valentine NW, et al. Influence of imaging on clinical decision making in the treatment of lower back pain. Radiology. 2001;220(2):393-9. (Level II evidence)
- Expert Panel on Neurologic Imaging:, Davis PC, Franz JW, Cornelius RS, Angtuaco EJ, Broderick DF, et al. Americal College of Radiology Appropriateness Criteria: Low back pain [online publication]. Reston, VA; 2011 [cited 2013 April 4]. (Evidence based guidelines) View the reference
- van Tulder M, Becker A, Bekkering T, Breen A, del Real M. European guidelines for the management of acute nonspecific low back pain in primary care. Eur Spine J. 2006;15(S2):S169-91. (Evidence based guidelines)
- Koes BW, van Tulder M, Lin CW, Macedo LG, McAuley J, Maher C. An updated overview of clinical guidelines for the management of non-specific low back pain in primary care. Eur Spine J. 2010;19(12):2075-94. (Review article)
- Australian Acute Musculoskeletal Pain Guidelines Group, National Health and Medical Research Council. Evidence-based Management of Acute Musculoskeletal Pain [online publication]. Brisbane: Australian Academic Press Pty Ltd; 2003 [cited 2013 February 26]. (Systematic review; Evidence based guidelines) View the reference
- Henschke N, Maher CG, Ostelo RW, de Vet HC, Macaskill P, Irwig L. Red flags to screen for malignancy in patients with low-back pain. Cochrane Database Syst Rev. 2013;2:CD008686. (Level II evidence)
- Williams CM, Henschke N, Maher CG, van Tulder MW, Koes BW, Macaskill P, et al. Red flags to screen for vertebral fracture in patients presenting with low-back pain. Cochrane Database Syst Rev. 2013;1:CD008643. (Level II evidence)
- van Tulder MW, Assendelft WJ, Koes BW, Bouter LM. Spinal radiographic findings and nonspecific low back pain. A systematic review of observational studies. Spine (Phila Pa 1976). 1997;22(4):427-34. (Level II evidence)
- Hollingworth W, Todd CJ, King H, Males T, Dixon AK, Karia KR, et al. Primary care referrals for lumbar spine radiography: diagnostic yield and clinical guidelines..Br J Gen Pract. 2002;52(479):475-80. (Level III evidence)
- de Schepper EI, Damen J, van Meurs JB, Ginai AZ, Popham M, Hofman A, et al. The association between lumbar disc degeneration and low back pain: the influence of age, gender, and individual radiographic features. Spine (Phila Pa 1976). 2010;35(5):531-6. (Level II evidence)
- Webster EW, Merrill OE. Radiation hazards. II. Measurements of gonadal dose in radiographic examinations. N Engl J Med. 1957;257(17):811-9. (Level II evidence)
- Antoku S, Russell WJ. Dose to the active bone marrow, gonads, and skin from roentgenography and fluoroscopy. Radiology. 1971;101(3):669-78. (Level II evidence)
- Chou R, Qaseem A, Snow V, Casey D, Cross JT, Jr., Shekelle P, et al. Diagnosis and treatment of low back pain: a joint clinical practice guideline from the American College of Physicians and the American Pain Society.[Erratum appears in Ann Intern Med 2008;148(3):247-8; PMID: 18257154], [Summary for patients in Ann Intern Med. 2007 Oct 2;147(7):I45; PMID: 17909203]. Ann Intern Med. 2007;147(7):478-91. (Evidence based guidelines)
- Jarvik JG, Deyo RA. Diagnostic evaluation of low back pain with emphasis on imaging. Ann Intern Med. 2002;137(7):586-97. (Review article)
- Modic MT, Obuchowski NA, Ross JS, Brant-Zawadzki MN, Grooff PN, Mazanec DJ, et al. Acute low back pain and radiculopathy: MR imaging findings and their prognostic role and effect on outcome. Radiology. 2005;237(2):597-604. (Level II evidence)
- Carragee E, Alamin T, Cheng I, Franklin T, van den Haak E, Hurwitz E. Are first-time episodes of serious LBP associated with new MRI findings? Spine J. 2006;6(6):624-35. (Level I evidence)
- Pineda C, Vargas A, Rodríguez AV. Imaging of Osteomyelitis: Current Concepts. Infect Dis Clin North Am. 2006;20(4):789-825. (Review article)
- Modic MT, Feiglin DH, Piraino DW, Boumphrey F, Weinstein MA, Duchesneau PM, et al. Vertebral osteomyelitis: assessment using MR. Radiology. 1985;157(1):157-66. (Level III evidence)
- Chiewvit P, Danchaivijitr N, Sirivitmaitrie K, Chiewvit S, Thephamongkhol K. Does magnetic resonance imaging give value-added than bone scintigraphy in the detection of vertebral metastasis? J Med Assoc Thai. 2009;92(6):818-29. (Level III evidence)
- Thariat J, Toubeau M, Ornetti P, Coudert B, Berrielo-Riedinger A, Fargeot P, et al. Sensitivity and specificity of thallium-201 scintigraphy for the diagnosis of malignant vertebral fractures. Eur J Radiol. 2004;51(3):274-8. (Level II evidence)
- Aitchison FA, Poon FW, Hadley MD, Gray HW, Forrester AW. Vertebral metastases and an equivocal bone scan: value of magnetic resonance imaging. Nucl Med Commun. 1992;13(6):429-31. (Level III evidence)
- Algra PR, Bloem JL, Tissing H, Falke TH, Arndt JW, Verboom LJ. Detection of vertebral metastases: comparison between MR imaging and bone scintigraphy. Radiographics. 1991;11(2):219-32. (Level II evidence)
- Thawait SK, Marcus MA, Morrison WB, Klufas RA, Eng J, Carrino JA. Research synthesis: what is the diagnostic performance of magnetic resonance imaging to discriminate benign from malignant vertebral compression fractures? Systematic review and meta-analysis. Spine. 2012;37(12):E736-44. (Level I evidence)
- Wassenaar M, van Rijn RM, van Tulder MW, Verhagen AP, van der Windt DA, Koes BW, et al. Magnetic resonance imaging for diagnosing lumbar spinal pathology in adult patients with low back pain or sciatica: a diagnostic systematic review. Eur Spine J. 2012;21(2):220-7. (Level I/II evidence)
- Thornbury JR, Fryback DG, Turski PA, Javid MJ, McDonald JV, Beinlich BR, et al. Disk-caused nerve compression in patients with acute low-back pain: diagnosis with MR, CT myelography, and plain CT. Radiology. 1993;186(3):731-8. (Level II evidence)
- Jensen TS, Karppinen J, Sorensen JS, Niinimaki J, Leboeuf-Yde C. Vertebral endplate signal changes (Modic change): a systematic literature review of prevalence and association with non-specific low back pain. Eur Spine J. 2008;17(11):1407-22. (Level II evidence)
- Boden SD, Davis DO, Dina TS, Patronas NJ, Wiesel SW. Abnormal magnetic-resonance scans of the lumbar spine in asymptomatic subjects. A prospective investigation. J Bone Joint Surg Am. 1990;72(3):403-8. (Level II evidence)
- Jarvik JJ, Hollingworth W, Heagerty P, Haynor DR, Deyo RA. The Longitudinal Assessment of Imaging and Disability of the Back (LAIDBack) Study: baseline data. Spine (Phila Pa 1976). 2001;26(10):1158-66. (Level I evidence)
- Schwarzer AC, Wang SC, O'Driscoll D, Harrington T, Bogduk N, Laurent R. The ability of computed tomography to identify a painful zygapophysial joint in patients with chronic low back pain. Spine (Phila Pa 1976). 1995;20(8):907-12. (Level II evidence)
- Williams AL, Gornet MF, Burkus JK. CT evaluation of lumbar interbody fusion: current concepts. AJNR Am J Neuroradiol. 2005;26(8):2057-66. (Review article)
- van Rijn RM, Wassenaar M, Verhagen AP, Ostelo RW, Ginai AZ, de Boer MR, et al. Computed tomography for the diagnosis of lumbar spinal pathology in adult patients with low back pain or sciatica: a diagnostic systematic review. Eur Spine J. 2012;21(2):228-39. (Level II evidence)
- Yussen PS, Swartz JD. The acute lumbar disc herniation: imaging diagnosis. Semin Ultrasound CT MR. 1993;14(6):389-98. (Review article)
- Albeck MJ, Hilden J, Kjaer L, Holtas S, Praestholm J, Henriksen O, et al. A controlled comparison of myelography, computed tomography, and magnetic resonance imaging in clinically suspected lumbar disc herniation. Spine (Phila Pa 1976). 1995;20(4):443-8. (Level II evidence)
- Jackson RP, Cain JE, Jr., Jacobs RR, Cooper BR, McManus GE. The neuroradiographic diagnosis of lumbar herniated nucleus pulposus: II. A comparison of computed tomography (CT), myelography, CT-myelography, and magnetic resonance imaging. Spine (Phila Pa 1976). 1989;14(12):1362-7. (Level II evidence)
- Manchikanti L, Glaser SE, Wolfer L, Derby R, Cohen SP. Systematic review of lumbar discography as a diagnostic test for chronic low back pain. Pain Physician. 2009;12(3):541-59. (Level II evidence)
- Carragee E, Don A, Hurwitz E, Cuellar J, Carrino J. 2009 ISSLS Prize Winner. Does discography cause accelerated progression of degeneration changes in the lumbar disc: a ten-year matched cohort study. Spine (Phila Pa 1976). 2009;34(21):2338-45. (Level II evidence)
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