Course Outline. Diagnostic Imaging for Low Back Pain: Just Say No. Commonest Imaging Methods

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1 Course Outline Diagnostic Imaging for Low Back Pain: Just Say No Chad Cook PhD, PT, MBA, FAAOMPT Professor and Chair Walsh University 1. Operational definition of Common Imaging Methods for Low Back Pain 2. Cost and Benefits, and Physiological Risks Associated with Imaging 3. Low Back Pain Related Guidelines for Use of Imaging 4. Diagnostic Accuracy of Imaging for Low Back Pain 5. Recommendations Commonest Imaging Methods Operational Definition of Common Imaging Methods for Low Back Pain Part One Plain Film Radiograph Computed Tomography Scan Magnetic Resonance Imaging Bone Scan Discography Lateef H, Patel D. What is the role of imaging in acute low back pain? Curr Rev Musculoskelet Med. 2009;2: Definition-Plain Film Radiograph X-rays are photons that are directed through the body to a receptive film. Areas of the body that attenuate the x-ray the most will appear white (e.g., bone, metal, etc) whereas areas that attenuate very little leave darkened film (e.g, air, fat, soft tissue) Uses of Plain Film Radiograph X-rays are primarily used to define markers of degeneration, during suspicion of a tumor, or for assessment of a fracture. Oblique films (and other views) are ordered when there is suspicion of spondylolysis, as suggestive from history and physical examination. Major N. A practical approach to radiology. Philadelphia. Saunders

2 Definition-Computed Tomography Scan A CT scan is a mathematical reconstruction of an x-ray scan of cross sectional slices of patient tissue. It can be threedimensionally constructed Uses of Computed Tomography Scan Computed tomography (CT) has superior depiction of cortical bone than MRI and may be best at visualizing fractures, especially of the posterior elements and facet degenerative changes Major N. A practical approach to radiology. Philadelphia. Saunders Jarvik J, Deyo R. Diagnostic evaluation of low back pain with emphasis on imaging. Ann Intern Med. 2002;137: Definition-Magnetic Resonance Imaging An MRI uses radiowaves and magnetic fields to produce a topographical image T1 weighted image the fluid is typically dark T2 weighted image the fluid is typically light Uses of Magnetic Resonance Imaging Able to view tumors, facet joint degeneration, soft tissue trauma, and abnormal disc morphology, collapse, and high-intensity zones MRI does not require radiation exposure and provides excellent visualization of soft tissue and spinal canal Major N. A practical approach to radiology. Philadelphia. Saunders Pfirrmann CW, Metzdorf A, Zanetti M, et al. Magnetic resonance classification of lumbar intervertebral disc degeneration. Spine 2001;26: Definition-Bone Scan A bone scan (bone scintigraphy) is a nuclear scanning test designed to target abnormalities in bone that are triggering the bone's attempts to heal. An injection of a small amount of radioactive material is used prior to the scan to look for a disruption of normal bone turnover (5 to 15% is considered significant) Uses of a Bone Scan Bone scans are used mainly to detect occult fractures, stress fractures, infections, or bony metastases and to differentiate them from degenerative changes Can differentiate between an acute versus healed compression fracture because new fractures will appear hot Major N. A practical approach to radiology. Philadelphia. Saunders Jarvik J, Deyo R. Diagnostic evaluation of low back pain with emphasis on imaging. Ann Intern Med. 2002;137:

3 Definition-Discography An invasive approach where a needle is inserted (under fluoroscopy) into the disc and fluid is injected to increase the pressure of the disk. Contrast agent is then inserted an a CT scan is used to detect leakage of disc material. Uses of Discography Most commonly ordered prior to a lumbar fusion. May help support theory of causation of lumbar radiculopathy Numerous contraindications and adverse reactions (e.g., infection) Costs Affiliated with Each? Cost and Benefit, and Physiological Risks Associated with Imaging Part Two Depends on the tool Depends on the location (e.g, hospital, outpatient) Depends on who reads it and charges Depends on the body part Depends on how many views Depends on one s insurance Means Costs (margin) CT Scan$1520 ($415) (In 2007, 2.2 million lumbar CT scans were performed in the US) MRI $2048 ($101) Nuclear Medicine $1138 ($149) X-ray $410 ($171) Sistrom C, McKay N. Costs, charges, and revenues for hospital diagnostic imaging procedures: Differences by modality and hospital characteristics. J Am Coll Radiol. 2005;2: Average Cost per Patient X-ray costs the average patient $44 out of pocket MRI costs the average patient $126 out of pocket Gray D, et al. Conventional Radiography, Rapid MR Imaging, and Conventional MR Imaging for Low Back Pain: Activity based Costs and Reimbursement. Radiology. 2003;227:

4 Global Benefits of Imaging E.g., Cauda Equina Appropriate visualization of red flags Good diagnostic accuracy Has fostered specialization and research Helps strategize for surgical intervention Helps define origin of lesion Hillman BJ. The Past 25 Years in Medical Imaging Research: A Memoir. Radiology. 2000:214: Fairbank et al. Does patient history and physical examination predict MRI proven cauda equina syndrome? Spine Care J. 2011: 2: Generic Imaging? A recent RCT (N=1804) demonstrated that outcomes for acute and sub-acute LBP were similar between groups who did and did not receive imaging Detrimental Aspects to Imaging There is no evidence to prove that obtaining X- rays is associated with better patient outcomes Another drawback of lower back X-ray in acute back pain are the identification of certain abnormalities that are only incidental findings and are unrelated to the back symptoms as most of these conditions are seen in persons without back pain Chou et al. Imaging strategies for low back pain: A systematic review and meta analysis. Lancet. 2009;373: Deyo RA, et al Reducing roentgenography use. Arch Intern Med. 1987;147: Kerry S, et al. Br J Gen Pract. 2002;52: VanTulder et al. Spine. 1997;22: Unnecessary Labeling There is evidence that telling patients that they have an imaging abnormality has negative effects related to labeling Individuals who are told they have a structural pathology identified on an MRI had lower reported health statuses 1 year later (versus a randomized comparator) Physiological Risks associated with Exposure A drawback of lumbar radiography is exposure of gonads to ionizing radiation, especially with oblique view or multiple exposures. Flynn TW, Smith B, Chou R. Appropriate use of diagnostic imaging in low back pain: a reminder that unnecessary imaging may do as much harm as good. J Orthop Sports Phys Ther Nov;41(11): VanTulder MW, Assendelft WJ, Koes BW, Bouter LM. Spinal radiographic findings and nonspecific low back pain. A systemic review of observational studies. Spine. 1997;22:

5 Exposure in msv with X-ray Exposure with CT Scan For comparison, in the United States we receive about 3.0 msv (300 mrem) of exposure from natural background radiation every year. United Nations Scientific Committee on the Effects of Atomic Radiation. Sources and effects of ionizing radiation, Vol. 1: Sources. New York, NY: United Nations Publishing; United Nations Scientific Committee on the Effects of Atomic Radiation. Sources and effects of ionizing radiation, Vol. 1: Sources. New York, NY: United Nations Publishing; In Terms of Days Equivalent Radiation Calculator Website Mettler F, et al. Effective Doses in Radiology and Diagnostic Nuclear Medicine: A Catalog, Radiology 2008;248, No. 1, pp What are Guidelines? Low Back Pain Related Guidelines for Use of Imaging Part Three 5

6 Most Commonly Accepted Imaging Guidelines Chou R, Qaseem A, Snow V, 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. Ann Intern Med 2007; 147(7): Severe progressive neurologic impairments or signs or symptoms indicating a serious or specific underlying condition, or if patient is candidate for invasive interventions For acute low back pain with major risk factors for cancer, risk factors for spinal infection, risk factors for or signs of the cauda equina syndrome, or severe or progressive neurologic deficits. Imaging after a trial of treatment is recommended with minor risk factors for cancer, risk factors for inflammatory back disease, risk factors for vertebral compression fracture, signs or symptoms of radiculopathy, or risk factors for or symptoms of symptomatic spinal stenosis. Decisions for subsequent imaging should be guided by development of new symptoms or changes in current symptoms, (new or changed low back symptoms.) It s a Big Deal! Conflicts of interest (62% of guidelines creators had a vested interest in the diagnostic or interventional guidelines they advocate) Some guidelines involve findings as high as 87-90% (Jones et al., Ann Intern Med, 2012) Top deficient findings in the Agree II guidelines Suggested in Suspicion of Red Flags Signs and Symptoms found in the patient history and clinical examination that may tie a disorder to a serious pathology. Sometimes is identified as a finding that is reflective of a delayed or poor outcome. We will call this a prognostic red flag. Bigos S, Bowyer O, Braen G, et al. Acute low back problems in adults: clinical practice guideline No. 14. AHCPR publication No Rockville, MD: Agency for Health Care Policy and Research, Public Health Service, US Department of Health and Human Services;

7 Indications of Each Imaging (for the low back) particularly with advanced modalities is rarely indicated, even for elderly patients. Chou R, 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. Ann Int Med 2007;147: Institute for Clinical Systems Improvement. Adult low back pain. ICSI; Bloomington, MN: Sep Prevalence's for Need of Imaging Consider the recommendations of the ACR Guidelines approximately 5-10% of subjects may be candidates for imaging (out of all of LBP). Jarvik JG, Deyo RA. Diagnostic evaluation of low back pain with emphasis on imaging. Ann Intern Med 2002 Oct 1;137(7): How Frequently it is Used N = 35,039 (Medicare [65 and older]) 28.8% of 35,039 beneficiaries with LBP were imaged within 28 days, and an additional 4.6% between days. Among imaged patients, 88.2% had a radiograph, while 11.8% had CT/MRI as their initial study. AHRQ Low Back Guidelines During the comparison of before and after the AHRQ guidelines were published: Radiography ordering increased slightly from 15.4 to 19.4% Physical therapy referrals declined from 27 to 22%. Pham et al. Rapidity and Modality of Imaging for Acute Low Back Pain in Elderly Patients Arch Intern Med May 25; 169(10): Jackson JL, Browing R. Impact of national low back pain guidelines on clinical practice. South Med J Feb;98(2): How Frequently is MRI Used Deyo RA, Mirza SK, Turner JA, Martin BI. Overtreating chronic back pain: time to back off? J Am Board Fam Med. 2009;22: How well do we follow guidelines? Journal of the American College of Radiology found that 26% of medical images ordered were inappropriate, and found a 53% inappropriate referral rate for CT and 35% inappropriate referral rate for MRI. Lehnert BE, Bree RL. Analysis of appropriateness of outpatient CT and MRI referred from primary care clinics at an academic medical center: how critical is the need for improved decision support? J Am Coll Radiol. 2010;7:

8 Why Don t Physicians Follow Guidelines Defensive Medicine They Don t Know the Guidelines Both orthopaedic surgeons' and family physicians' knowledge of treating LBP is deficient. Orthopedic surgeons are less aware of current treatment than family practitioners (mean score on standard study of 44% versus 69%. Finestone et al. Orthopaedists' and family practitioners' knowledge of simple low back pain management. Spine. 2009;34(15): Pressure from Patients Patients typically feel they need imaging for their current low back pain Most pressure is in outpatient oriented environments Physicians (even those who know the guidelines) deter to patient s requests Wilson et al. Patients' role in the use of radiology testing for common office practice complaints. Arch Intern Med Jan 22;161(2): Tracy et al. The nexus of evidence, context, and patient preferences in primary care: postal survey of Canadian family physicians. BMC Fam Pract Sep 23;4:13. Epub 2003 Sep 23. Worth Noting Imaging does not alleviate psychological concerns and patient fears about their low back pain, nor is it likely to identify a hidden sinister provide that was missed during a clinical examination. Flynn TW, Smith B, Chou R. Appropriate use of diagnostic imaging in low back pain: a reminder that unnecessary imaging may do as much harm as good. J Orthop Sports Phys Ther Nov;41(11): Because their Clinical Exam Skills are Poor Why else?, Because They re Physicians! It is well documented that physicians have lost clinical examination capabilities over the last several decades Part or most of the decline has been associated with training weaknesses, weaknesses associated with patient history taking, and an overemphasis on organ-based diagnoses and an under-emphasis on physical management. Cook C. The lost art of the clinical examination. An over emphasis on special tests. J Man Manip Ther. 2010:18:1 4. 8

9 Diagnostic Accuracy Diagnostic Accuracy of Imaging Methods for Low Back Pain Part Four The study of diagnostic accuracy looks at the ability of a clinical testing method (clinical, laboratory, or imaging) to identify pathology when it is properly present and to identify no pathology when it is properly absence. Very strong tests have the ability to discriminate against different disorders from the same body region. The Language of Diagnostic Accuracy Sensitivity: Percentage of people who test positive for a specific disease among a group of people who have the disease Specificity: Percentage of people who test negative for a specific disease among a group of people who do not have the disease Sensitivity Example 50 patients with arm pain associated with cervical radiculopathy Test was positive in 40 of the 50 cases Sensitivity = 40/50 or 80% Correct 80% of the time in cases that were cervical radiculopathy Specificity Example 50 patients with no arm pain associated with a cervical strain Test was positive in 5 of the 50 cases Specificity = 45/50 or 90% Correct 90% of the time in cases that were NOT cervical radiculopathy Likelihood Ratios A high LR+ influences post-test probability with a positive finding A value of >1 rules in a diagnosis A low LR- influences post-test probability with a negative finding A value closer to 0 is best and rules out Bossuyt P, Reitsma J, Bruns D, Catsonis C, Glasziou P, Irwig L, Lijmer J, Moher D, Rennie D, de Vet H. Towards complete and accurate reporting of studies of diagnostic accuracy: the STARD initiative. Family Practice. 2004;21:

10 Likelihood Ratio and Nomograms Pretest prob + injury and pop=20% LR+ Lachman s test = 9.0 Post test prob = 69% Confidence Intervals- Lachmans Pretest prob + injury and pop=20% Lachman s test = 9.0 (95%CI =2.5, 24.3) Post test prob = 69% (95%CI= 38%, 83%) Influencing Decision Making How Accurate is Imaging? Cook C. Orthopedic Manual Therapy. An Evidence Based Approach. Prentice Hall; Upper Saddle 57 River, NJ: False Positives with MRI and HNP Study Presence of Disc Bulge Presence of Disc Protrusion Presence of Disc Extrusion Boden et al NR 20% NR Boos et al NR 63% 13% Jensen et al. 52% 27% 1% 1994 Weishaupt et al. 24% 40% 18% 1998 Wood et al % 37% NR An MRI for Diagnosis of HNP MRI studies identified 22 40% of adults with herniated disk, who are asymptomatic and pain free; one study found 81% of such asymptomatic individuals with a bulging disk Jarvik J, Deyo R. Diagnostic evaluation of low back pain with emphasis on imaging. Ann Intern Med. 2002;137:

11 MRI for Nerve Involvement Sensitivity of 20 and Specificity of 80 (Bertelson) MRI-Identification of Cancer in LBP Joines et al. Finding Cancer in Primary Care Outpatients with Low Back Pain: A Comparison of Diagnostic Strategies. J Gen Intern Med January; 16(1): MRI and Cancer and Infection Sensitivity for cancer was highest for magnetic resonance imaging (0.83 to 0.93) and radionuclide scanning (0.74 to 0.98); specificity was highest for magnetic resonance imaging (0.9 to 0.97) and radiography (0.95 to 0.99). Magnetic resonance imaging was the most sensitive (0.96) and specific (0.92) test for infection. The sensitivity and specificity of magnetic resonance imaging for herniated discs were slightly higher than those for computed tomography but very similar for the diagnosis of spinal stenosis. Jarvik JG, Deyo RA. Diagnostic evaluation of low back pain with emphasis on imaging. Ann Intern Med Oct 1;137(7): The lower specificity of MRI can be attributed to the high prevalence of degeneration (46 93%) and protrusions (20 80%) in asymptomatic adults Jarvik JG, Haynor DR, Hollingworth W, et al. Longitudinal assessment of imaging and disability of the back: a prospective cohort study of asymptomatic VA patients. (abstr) Proceedings of the Radiological Society of North America annual meeting. Chicago, IL: Radiological Society of North America, 1999 MRI Different Parameters MRI Parameters (another) The best Bulge disc contour Mod loss of disc height Mod loss of nuclear signal Limited Value Everything else O Neil et al. Pain Physician 2008; 11:3: Kang et al. Skeletal Radiol (2009) 38:

12 MRI and MRI with Myelography The sensitivity, specificity, +LR and -LR of MRI for the diagnosis of symptomatic foraminal stenosis were 96%, 67%, 2.9, and 0.06, respectively. The corresponding values for abnormal nerve root course on MRM were 96%, 83%, 5.6, and 0.05, respectively, and for spinal nerve swelling on MRM were 60%, 99%, 60.0, and 0.40, respectively. Aota et al. SPINE. 2007; Volume 32, Number 8, pp CT Scan for a Herniated Disc The pooled summary estimate of sensitivity was 77.4% (95% CI %) and the pooled summary estimate of specificity was 73.7% (95% CI %), resulting in a positive likelihood ratio of 2.94, and a negative likelihood ratio of Van Rijn 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: Bone Scan (SPECT) for Low Back Pain Provocative Discography for Surgical Prognosis Meta-analysis (adjusted prior publications) Verdict-Not useful Poor Prognostic ability Littenberg B, et al. J Nuci Med1995;36: Willems et al. Spinal fusion for chronic low back pain: systematic review on the accuracy of tests for patient selection. Spine J [E pub ahead of print] Recommendations Part Five Lurie J. Best Practice & Research Clinical Rheumatology Vol. 19, No. 4, pp ,

13 Linking the Examination and Imaging Comparison to Clinical Findings Comparison to Clinical Findings Jarvik and Deyo. Ann Intern Med. 2002;137: Non Mechanical Pain Cont. Cook C, Ross MD, Isaacs R, Hegedus E. Investigation of Nonmechanical Findings during Spinal Movement Screening for Identifying and/or Ruling Out Metastatic Cancer. Pain Pract Nov 22. doi: /j x. [Epub ahead of print]. Cook C, Ross MD, Isaacs R, Hegedus E. Investigation of Nonmechanical Findings during Spinal Movement Screening for Identifying and/or Ruling Out Metastatic Cancer. Pain Pract Nov 22. doi: /j x. [Epub ahead of print]. 13

14 Risk Reward Imaging everyone? Image only that with clinical findings? Image no one? MRI-Identification of Cancer in LBP Joines et al. Finding Cancer in Primary Care Outpatients with Low Back Pain: A Comparison of Diagnostic Strategies. J Gen Intern Med January; 16(1): Cervical Closed Fracture Vertebral Compression Fracture Female sex Age >70 years Significant trauma Prolonged use of corticosteroids 1 of 4 Sens = 88, Spec = 50, LR+ = of 4 Sens = 38, Spec = 100, LR+ = 218 Cook et al. In review. Pain Practice Henschke et al. Prevalence of and screening for serious spinal pathology in patients presenting to primary care settings with acute low back pain. Arthritis Rheum Oct;60(10): Clustered Results Compression Fracture Sensitivity (95% CI) Specificity (95% CI) Positive Likelihood Ratio (95% CI) 1 of 5 positive tests.97 ( ).06 ( ) 1.04 ( ) 2 of 5 positive tests.95 ( ).34 (.33.34) 1.4 ( ) 3 of 5 positive tests.76 ( ).68 ( ) 2.5 ( ) 4 of 5 positive tests.37 ( ).96 ( ) 9.6 ( ) 5 of 5 positive tests.03 ( ).99 ( ) 9.3 ( ) NOTE. Five findings are included in the rule: (1) age > 52 years; (2) no presence of leg pain; (3) body mass index < 22; (4) does not exercise regularly; and (5) female gender. Negative Likelihood Ratio (95% CI) 0.39 ( ) 0.16 ( ) 0.34 ( ) 0.65 ( ) 0.97 ( ) Roman M, Brown C, Richardson W, Isaacs R, Howes C, Cook C. The development of a clinical decision making algorithm for detection of osteoporotic vertebral compression fracture or wedge deformity. JMMT 2010;81: By comparison, imaging is slightly better Certainly more confirmatory Is typically not best used as a screen By Comparison 14

15 Diagnostic Accuracy of Clinical Judgement Diagnostic Accuracy of Clinical Judgement and Imaging Serious Minor Serious Minor (requires intervention) (requires no intervention) (requires intervention) (requires no intervention) TP FP All TP All FP Difference TN Difference All TN FN All FN Diagnostic Clinical Utility? You make that call Thank You Questions? 15