ACR Appropriateness Criteria®
Clinical Condition: Low Back Pain
Variant 1: Uncomplicated acute low back pain and/or radiculopathy, nonsurgical presentation. No red flags. (Red flags defined in the text below.)
| Radiologic Procedure |
Rating |
Comments |
RRL* |
| MRI lumbar spine without contrast |
2 |
|
None |
| X-ray lumbar spine |
2 |
|
Med |
| Myelography and postmyelography CT lumbar spine |
2 |
In some cases postinjection CT imaging may be done without myelography. |
High |
| X-ray myelography lumbar spine |
2 |
|
Med |
| NUC Tc-99m bone scan with SPECT spine |
2 |
|
Med |
| CT lumbar spine without contrast |
2 |
|
Med |
| MRI lumbar spine without and with contrast |
2 |
|
None |
| Rating Scale: 1=Least appropriate, 9=Most appropriate |
*Relative Radiation Level |
Note: Abbreviations used in the tables are listed at the end of the "Major Recommendations" field.
Variant 2: Low velocity trauma, osteoporosis, and/or age > 70.
| Radiologic Procedure |
Rating |
Comments |
RRL* |
| MRI lumbar spine without contrast |
8 |
|
None |
| CT lumbar spine without contrast |
6 |
MRI preferred. CT useful if MRI is contraindicated or unavailable, and/or for problem solving. |
Med |
| X-ray lumbar spine |
6 |
|
Med |
| NUC Tc-99 bone scan with SPECT spine |
4 |
|
Med |
| MRI lumbar spine without and with contrast |
3 |
|
None |
| Myelography and postmyelography CT lumbar spine |
1 |
In some cases postinjection CT imaging may be done without myelography. |
High |
| X-ray myelography lumbar spine |
1 |
|
Med |
| Rating Scale: 1=Least appropriate, 9=Most appropriate |
*Relative Radiation Level |
Note: Abbreviations used in the tables are listed at the end of the "Major Recommendations" field.
Variant 3: Suspicion of cancer, infection, or immunosuppression.
| Radiologic Procedure |
Rating |
Comments |
RRL* |
| MRI lumbar spine without and with contrast |
8 |
See comments regarding contrast in the text below under "Anticipated Exceptions." |
None |
| CT lumbar spine without contrast |
6 |
MRI preferred. CT useful if MRI is contraindicated or unavailable, and/or for problem solving. |
Med |
| X-ray lumbar spine |
5 |
|
Med |
| NUC Tc-99m bone scan whole body with optional targeted SPECT spine |
5 |
|
Med |
| X-ray myelography lumbar spine |
2 |
|
Med |
| Myelography and postmyelography CT lumbar spine |
2 |
In some cases postinjection CT imaging may be done without myelography. |
High |
| Rating Scale: 1=Least appropriate, 9=Most appropriate |
*Relative Radiation Level |
Note: Abbreviations used in the tables are listed at the end of the "Major Recommendations" field.
Variant 4: Low back pain and/or radiculopathy, surgery or intervention candidate.
| Radiologic Procedure |
Rating |
Comments |
RRL* |
| MRI lumbar spine without contrast |
8 |
|
None |
| CT lumbar spine without contrast |
5 |
MRI preferred. CT useful if MRI contraindicated or unavailable, and/or for problem solving. |
Med |
| MRI lumbar spine without and with contrast |
5 |
Indicated if noncontrast MRI is nondiagnostic or indeterminate. See comments regarding contrast in the text below under "Anticipated Exceptions." |
None |
| Myelography and postmyelography CT lumbar spine |
5 |
MRI preferred. May be indicated if MRI is contraindicated or nondiagnostic. In some cases postinjection CT imaging may be done without myelography. |
High |
| X-ray lumbar spine |
4 |
Usually not sufficient for decision making without MR and/or CT imaging. |
Med |
| NUC Tc-99m bone scan with SPECT spine |
4 |
May be particularly useful for facet arthropathy, stress fracture, and spondylolysis. |
Med |
| X-ray myelography lumbar spine |
2 |
|
Med |
| Rating Scale: 1=Least appropriate, 9=Most appropriate |
*Relative Radiation Level |
Note: Abbreviations used in the tables are listed at the end of the "Major Recommendations" field.
Variant 5: Prior lumbar surgery.
| Radiologic Procedure |
Rating |
Comments |
RRL* |
| MRI lumbar spine without and with contrast |
8 |
Differentiate disc versus scar. See comments regarding contrast in the text below under "Anticipated Exceptions." |
None |
| CT lumbar spine without contrast |
6 |
Most useful in postfusion patients or when MRI is contraindicated or indeterminate. |
Med |
| MRI lumbar spine without contrast |
6 |
Contrast often necessary |
None |
| Myelography and postmyelography CT lumbar spine |
5 |
In some cases postinjection CT imaging may be done without myelography. |
High |
| X-ray lumbar spine |
5 |
Flex/extension may be useful. |
Med |
| NUC Tc-99m bone scan with SPECT spine |
5 |
Helps detect and localize painful pseudoarthrosis. |
Med |
| X-ray myelography lumbar spine |
2 |
|
Med |
| Rating Scale: 1=Least appropriate, 9=Most appropriate |
*Relative Radiation Level |
Note: Abbreviations used in the tables are listed at the end of the "Major Recommendations" field.
Variant 6: Cauda equina syndrome.
| Radiologic Procedure |
Rating |
Comments |
RRL* |
| MRI lumbar spine without contrast |
9 |
Use of contrast depends on clinical circumstances. |
None |
| MRI lumbar spine without and with contrast |
8 |
Use of contrast depends on clinical circumstances. See comments regarding contrast in the text below under "Anticipated Exceptions." |
None |
| Myelography and postmyelography CT lumbar spine |
6 |
Useful if MRI is nondiagnostic or contraindicated. In some cases postinjection CT imaging may be done without myelography. |
High |
| CT lumbar spine with or without contrast |
5 |
May be indicated if MRI is confusing or contraindicated and myelography is not feasible. Use of contrast depends on clinical circumstances. |
Med |
| X-ray lumbar spine |
4 |
|
Med |
| NUC Tc-99m bone scan with SPECT spine |
2 |
|
Med |
| X-ray myelography lumbar spine |
2 |
|
Med |
| Rating Scale: 1=Least appropriate, 9=Most appropriate |
*Relative Radiation Level |
Note: Abbreviations used in the tables are listed at the end of the "Major Recommendations" field.
Summary of Literature Review
Acute low back pain (LBP) with or without radiculopathy is one of the most common health problems in the United States and is the leading cause of disability for persons younger than age 45. The cost of evaluating and treating acute LBP runs into billions of dollars annually, not including time lost from work.
Because of the high prevalence and high cost of dealing with this problem, government agencies have sponsored extensive studies that are now part of the growing body of literature on this subject. One of the earlier comprehensive studies was carried out in Quebec and was reported in the journal Spine in 1987. The U.S. Department of Health and Human Services convened a 23-member multidisciplinary panel of experts to review all of the literature on this subject, grade it, and develop a "Clinical Practice Guideline," which was published in December 1994. States have also convened similar panels in recent years, largely because of the rapidly rising workers' compensation claim burden being imposed on state budgets by LBP management.
It is now clear from the above studies and others that uncomplicated acute LBP or radiculopathy is a benign, self-limited condition that does not warrant any imaging studies. The vast majority of these patients are back to their usual activities within 30 days. The challenge for the clinician, therefore, is to distinguish that small segment within this large patient population that should be evaluated further because of suspicion of a more serious problem.
Indications of a more complicated status, often termed "red flags," include the following:
- Recent significant trauma, or milder trauma, age >50
- Unexplained weight loss
- Unexplained fever
- Immunosuppression
- History of cancer
- Intravenous (IV) drug use
- Prolonged use of corticosteroids, osteoporosis
- Age >70
- Focal neurologic deficit with progressive or disabling symptoms
- Duration longer than 6 weeks
Radiographs
Radiographs are recommended when any of the above red flags are present. Lumbar radiographs may be sufficient for the initial evaluation of the following red flags, with further imaging indicated for treatment planning: if findings are abnormal or inconclusive.
- Recent significant trauma (at any age)
- Osteoporosis
- Age >70
The initial evaluation of the LBP patient may also require further imaging if other red flags such as suspicion of cancer or infection are present.
Isotope Bone Scan
The role of the isotope bone scan in patients with acute LBP has changed in recent years with the wide availability of magnetic resonance imaging (MRI) and especially contrast-enhanced MRI. The bone scan is a moderately sensitive test for detecting the presence of tumor, infection, or occult fractures of the vertebrae but not for specifying the diagnosis. For spondylolysis or stress fracture in athletes, bone scintigraphy with single photon emission computed tomography (SPECT), followed by limited computed tomography (CT) if scintigraphy is positive, is more sensitive than MRI. Bone scintigraphy with SPECT can be useful to identify symptomatic facet disease in patients treated with facet injection.
High-resolution isotope imaging, including SPECT, may localize the source of pain in patients with articular facet osteoarthritis prior to therapeutic facet injection. Similar scans may be helpful in detecting and localizing the site of painful pseudoarthrosis in patients following lumbar spinal fusion. The test is contraindicated in pregnancy.
Plain and contrast-enhanced MRI has the ability to demonstrate inflammatory, neoplastic, and most traumatic lesions as well as show anatomic detail not available on isotope studies. Gadolinium-enhanced MRI reliably shows the presence and extent of spinal infection, and is useful in assessing therapy. MRI has therefore taken over the role of the isotope scan in many cases where the location of the lesion is known. The isotope scan remains invaluable when a survey of the entire skeleton is indicated (e.g., for metastatic disease).
Magnetic Resonance Imaging, Computed Tomography, Myelography, Myelography/CT
Uncomplicated acute LBP and/or radiculopathy (no red flags) do not warrant the use of any of these imaging studies. The early indiscriminate use of expensive imaging procedures in this common clinical setting has caused large increases in worker's compensation costs and in some cases has led to the perception that CT and MRI of the lumbar spine are not worth the cost. Adding to this controversy is the fact that nonspecific lumbar disc abnormalities are common and can be demonstrated readily on myelography, CT, and MRI, even in asymptomatic patients.
The appropriate use of these imaging procedures is an important challenge that has been extensively addressed in the major reviews referenced herein (see the original guideline). For example, LBP complicated by "red flags" suggesting infection or tumor may justify early use of CT or MRI even if radiographs are negative. The most common indication for the use of these imaging procedures, however, is the clinical setting of LBP complicated by radiating pain (radiculopathy, sciatica) or cauda equina syndrome (bilateral leg weakness, urinary retention, saddle anesthesia), usually due to herniated disc and/or canal stenosis.
Magnetic Resonance Imaging
MRI of the lumbar spine has become the initial imaging modality of choice in complicated LBP, displacing myelography and CT in recent years. Multidisciplinary agreement on terminology facilitates reporting of MRI findings. Although disc abnormalities are common on MRI in asymptomatic persons, acute back pain with radiculopathy suggests the presence of demonstrable nerve root compression on MRI. MRI findings of Modic endplate change, anterolisthesis, or disc extrusion are more strongly associated with low back pain than disc degeneration without endplate change. A randomized controlled trial showed that depiction of stenosis and/or nerve root compression on MRI in the first 48 hours after acute back pain or radiculopathy onset did not affect outcome after 6 weeks of conservative management. MRI is particularly efficacious for detecting "red flag" diagnoses, particularly using the short tan inversion recovery (STIR) and fat-saturated T2 fast-spin-echo sequences. MR with contrast is useful for suspected infection and neoplasia. In postop patients, enhanced MRI allows distinction between disc and scar when tissue extends beyond the interspace.
Computed Tomography
CT scans provide superior bone detail but are not quite as useful in depicting disc protrusions when compared with multiplanar MRI. With the added value associated with high-quality reformatted sagittal and coronal plane images, CT is useful for depicting spondylolysis, pseudoarthrosis, scoliosis, and for post-surgical evaluation of bone graft integrity, surgical fusion, and instrumentation.
Myelography/CT
"Plain" myelography was the mainstay of lumbar herniated disc diagnosis for decades. It is now usually combined with postmyelography CT. The combined study is complementary to plain CT or MRI and occasionally more accurate in diagnosing disc herniation, but it suffers the disadvantage of requiring lumbar puncture and contrast injection. It may also be useful in surgical planning.
Thermography, Discography, CT Discography
Expert panels have agreed that these imaging modalities are either too nonspecific (thermography) or carry additional risk (discography) that is not warranted in view of the efficacy of other less invasive imaging procedures. When other studies fail to localize the cause of pain, discography may occasionally be helpful. Although the images often depict nonspecific aging or degenerative changes, the injection itself may reproduce the patient's pain, which may have diagnostic value.
Anticipated Exceptions
Nephrogenic systemic fibrosis (NSF, also known as nephrogenic fibrosing dermopathy) was first identified in 1997 and has recently generated substantial concern among radiologists, referring doctors and lay people. Until the last few years, gadolinium-based MR contrast agents were widely believed to be almost universally well tolerated, extremely safe and non-nephrotoxic, even when used in patients with impaired renal function. All available experience suggests that these agents remain generally very safe, but recently some patients with renal failure who have been exposed to gadolinium contrast agents (the percentage is unclear) have developed NSF, a syndrome that can be fatal. Further studies are necessary to determine what the exact relationships are between gadolinium-containing contrast agents, their specific components and stoichiometry, patient renal function and NSF. Current theory links the development of NSF to the administration of relatively high doses (e.g., >0.2mM/kg) and to agents in which the gadolinium is least strongly chelated. The U.S. Food and Drug Administration (FDA) has recently issued a "black box" warning concerning these contrast agents (http://www.fda.gov/cder/drug/InfoSheets/HCP/gcca_200705HCP.pdf).
This warning recommends that, until further information is available, gadolinium contrast agents should not be administered to patients with either acute or significant chronic kidney disease (estimated glomerular filtration rate [GFR] <30 mL/min/1.73m2), recent liver or kidney transplant or hepato-renal syndrome, unless a risk-benefit assessment suggests that the benefit of administration in the particular patient clearly outweighs the potential risk(s).
Abbreviations
- CT, computed tomography
- Med, medium
- MRI, magnetic resonance imaging
- NUC, nuclear medicine
- SPECT, single photon emission computed tomography
- Tc, technetium
| Relative Radiation Level |
Effective Dose Estimated Range |
| None |
0 |
| Minimal |
<0.1 mSv |
| Low |
0.1-1 mSv |
| Medium |
1-10 mSv |
| High |
10-100 mSv |
