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Imaging the Cervical, Thoracic, and Lumbar Spine
CHAPTER 3 Imaging the Cervical,
Thoracic, and Lumbar Spine Joshua Broder, MD, FACEP
screening tool for suspected cervical spine injury in children. We discuss the radiation burden and cost of cervical CT. The new ACR recommendation for a CTfirst strategy guarantees an increase in the radiation exposure resulting from any screening for cervical spine injury. Consequently, an even greater emphasis should be placed on applying reliable CDRs. Let’s begin our discussion with the cervical spine, followed by a parallel discussion of the thoracic and lumbar spine.
In this chapter, we discuss imaging of the cervical, thoracic, and lumbar spine. Although differences exist, many common themes are shared in both the selection and the interpretation of diagnostic studies for all regions of the spine. Our discussion of all spinal regions starts with interpretation of images, with a focus on computed tomography (CT) scan. We correlate CT findings with x-ray when possible, and we demonstrate associated soft-tissue abnormalities identified on magnetic resonance imaging (MRI). Don’t be daunted by the number of figures in this chapter—we explore injuries and nontraumatic spinal pathology in many imaging planes and in multiple modalities to maximize your three-dimensional understanding. The figure captions are designed to allow the figures to stand alone, so we spend relatively little time discussing specific fracture patterns in the text. The figures in the chapter span a range of important spinal pathology, moving from cephalad to caudad. The list in Table 3-1 can guide you to the relevant figure, where diagnostic features are discussed in detail.
EPIDEMIOLOGY OF CERVICAL SPINE INJURY Cervical spine injuries occur in approximately 2% to 4% of blunt trauma cases, and diagnostic imaging plays a pivotal role in the evaluation of patients for these potentially life-threatening or seriously debilitating injuries. In addition, nontraumatic cervical spine pathology occasionally requires imaging in the emergency department. This evaluation differs from the evaluation in trauma, as fractures or other bony pathology may not be present. The incidence of cervical injuries is relatively independent of the setting—level I, II, and III trauma centers (the U.S. designation) all encounter cervical spine injuries with similar frequency, and emergency physicians must be intimately familiar with the imaging required to diagnose these dangerous injuries. In one study of 165 U.S. medical centers involving 111,219 patients, 4.3% of patients had injuries, at similar rates, in both academic and nonacademic centers, regardless of trauma center type (I through III).2 The National Emergency X-radiography Utilization Study group, which is discussed in more detail later in regard to its CDR, found similar rates of injury: 2.4% of 34,069 patients in 21 U.S. medical centers.3-5
In many ways, the more difficult task for the emergency physician is not the interpretation of the image but the decision to image the spine. We review two wellvalidated clinical decision rules (CDRs) that can identify patients at low risk of cervical spine injury who do not require any imaging. Similar decision instruments can identify patients who require thoracic and lumbar imaging. Imaging of the spine has undergone a revolution with the advent of multidetector CT with multiplanar reconstructions. We review the evidence for use of CT and x-ray, comparing their sensitivity for detection of fractures. Remarkably, the latest version of the American College of Radiology (ACR) Appropriate Guidelines for Imaging of Suspected Spine Trauma (2009) advocates thin-section CT as the primary screening study for suspected cervical spine injury in adults, removing plain radiography (x-ray) from this position. The three-view radiograph that has been the long-standing screening test in the emergency department is now recommended by the ACR “only when CT is not readily available.”1 Radiography is described in this document as “not … a substitute for CT.”1 The ACR cites a lack of evidence for recommendations of CT or x-ray as the primary
IMAGING THE CERVICAL SPINE FOLLOWING TRAUMA: APPLICATION AND INTERPRETATION OF IMAGING MODALITIES Cervical spine imaging following trauma must perform a number of clinical functions. These include identification of fractures, ligamentous injuries, and injuries to neurologic structures, including the spinal cord and nerve roots. Diagnostic modalities for cervical spine imaging are plain film, CT scan, and MRI. We consider 73
Thoracic, and Lumbar Spine Joshua Broder, MD, FACEP
screening tool for suspected cervical spine injury in children. We discuss the radiation burden and cost of cervical CT. The new ACR recommendation for a CTfirst strategy guarantees an increase in the radiation exposure resulting from any screening for cervical spine injury. Consequently, an even greater emphasis should be placed on applying reliable CDRs. Let’s begin our discussion with the cervical spine, followed by a parallel discussion of the thoracic and lumbar spine.
In this chapter, we discuss imaging of the cervical, thoracic, and lumbar spine. Although differences exist, many common themes are shared in both the selection and the interpretation of diagnostic studies for all regions of the spine. Our discussion of all spinal regions starts with interpretation of images, with a focus on computed tomography (CT) scan. We correlate CT findings with x-ray when possible, and we demonstrate associated soft-tissue abnormalities identified on magnetic resonance imaging (MRI). Don’t be daunted by the number of figures in this chapter—we explore injuries and nontraumatic spinal pathology in many imaging planes and in multiple modalities to maximize your three-dimensional understanding. The figure captions are designed to allow the figures to stand alone, so we spend relatively little time discussing specific fracture patterns in the text. The figures in the chapter span a range of important spinal pathology, moving from cephalad to caudad. The list in Table 3-1 can guide you to the relevant figure, where diagnostic features are discussed in detail.
EPIDEMIOLOGY OF CERVICAL SPINE INJURY Cervical spine injuries occur in approximately 2% to 4% of blunt trauma cases, and diagnostic imaging plays a pivotal role in the evaluation of patients for these potentially life-threatening or seriously debilitating injuries. In addition, nontraumatic cervical spine pathology occasionally requires imaging in the emergency department. This evaluation differs from the evaluation in trauma, as fractures or other bony pathology may not be present. The incidence of cervical injuries is relatively independent of the setting—level I, II, and III trauma centers (the U.S. designation) all encounter cervical spine injuries with similar frequency, and emergency physicians must be intimately familiar with the imaging required to diagnose these dangerous injuries. In one study of 165 U.S. medical centers involving 111,219 patients, 4.3% of patients had injuries, at similar rates, in both academic and nonacademic centers, regardless of trauma center type (I through III).2 The National Emergency X-radiography Utilization Study group, which is discussed in more detail later in regard to its CDR, found similar rates of injury: 2.4% of 34,069 patients in 21 U.S. medical centers.3-5
In many ways, the more difficult task for the emergency physician is not the interpretation of the image but the decision to image the spine. We review two wellvalidated clinical decision rules (CDRs) that can identify patients at low risk of cervical spine injury who do not require any imaging. Similar decision instruments can identify patients who require thoracic and lumbar imaging. Imaging of the spine has undergone a revolution with the advent of multidetector CT with multiplanar reconstructions. We review the evidence for use of CT and x-ray, comparing their sensitivity for detection of fractures. Remarkably, the latest version of the American College of Radiology (ACR) Appropriate Guidelines for Imaging of Suspected Spine Trauma (2009) advocates thin-section CT as the primary screening study for suspected cervical spine injury in adults, removing plain radiography (x-ray) from this position. The three-view radiograph that has been the long-standing screening test in the emergency department is now recommended by the ACR “only when CT is not readily available.”1 Radiography is described in this document as “not … a substitute for CT.”1 The ACR cites a lack of evidence for recommendations of CT or x-ray as the primary
IMAGING THE CERVICAL SPINE FOLLOWING TRAUMA: APPLICATION AND INTERPRETATION OF IMAGING MODALITIES Cervical spine imaging following trauma must perform a number of clinical functions. These include identification of fractures, ligamentous injuries, and injuries to neurologic structures, including the spinal cord and nerve roots. Diagnostic modalities for cervical spine imaging are plain film, CT scan, and MRI. We consider 73